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Document And Entity Information	12 Months Ended
Document And Entity Information	Dec. 31, 2013 USD ($) shares
Document And Entity Information [Abstract]
Document Type	8-K
Document Period End Date	Dec. 31, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	FY
Entity Registrant Name	BOSTON PROPERTIES LTD PARTNERSHIP
Amendment Flag	false
Entity Central Index Key	0001043121
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding \| shares	0
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float \| $	$ 0

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Real estate, at cost	$ 18,548,441	$ 14,454,962
Less: accumulated depreciation	(3,096,910)	(2,876,983)
Total real estate	15,451,531	11,577,979
Cash and cash equivalents	2,365,137	1,041,978
Cash held in escrows	57,201	55,181
Investments in securities	16,641	12,172
Tenant and other receivables (net of allowance for doubtful accounts of $1,636 and $1,960, respectively)	59,464	69,555
Related party notes receivable	0	282,491
Interest receivable from related party notes receivable	0	104,816
Accrued rental income (net of allowance of $3,636 and $1,571, respectively)	651,603	598,199
Deferred charges, net	884,450	588,235
Prepaid expenses and other assets	184,477	90,610
Investments in unconsolidated joint ventures	126,084	659,916
Total assets	19,796,588	15,081,132
Liabilities:
Mortgage notes payable	4,449,734	3,102,485
Unsecured senior notes (net of discount of $14,146 and $10,472, respectively)	5,835,854	4,639,528
Unsecured exchangeable senior notes (net of discount of $182 and $1,653, respectively	744,880	1,170,356
Unsecured line of credit	0	0
Mezzanine notes payable	311,040	0
Outside members' notes payable	180,000	0
Accounts payable and accrued expenses	202,470	199,102
Distributions payable	497,242	110,488
Accrued interest payable	167,523	72,461
Other liabilities	578,969	324,613
Total liabilities	12,967,712	9,619,033
Commitments and contingencies	0	0
Noncontrolling interests:
Redeemable interest in property partnerships	99,609	97,558
Redeemable partnership units-666,116 and 995,997 series two preferred units outstanding (874,168 and 1,307,083 common units at redemption value, if converted) at December 31, 2013 and December 31, 2012, respectively	87,740	138,302
Redeemable partnership units - 360,126 and 1,221,527 series four preferred units outstanding at redemption value at December 31, 2013 and December 31, 2012, respectively	18,006	61,076
Redeemable partnership units-15,583,370 and 16,053,497 common units and 1,455,761 and 1,303,296 long term incentive units outstanding at redemption value at December 31, 2013 and December 31, 2012, respectively	1,710,218	1,836,522
Capital:
5.25% Series B cumulative redeemable preferred units, liquidation preference $2,500 per unit, 80,000 and no units issued and outstanding at December 31, 2013 and December 31, 2012, respectively	193,623	0
Boston Properties Limited Partnership partners' capital-1,700,222 and 1,689,580 general partner units and 151,282,879 and 149,911,629 limited partner units outstanding at December 31, 2013 and December 31, 2012, respectively	3,993,548	3,330,605
Noncontrolling interests in property partnerships	726,132	(1,964)
Total capital	4,913,303	3,328,641
Total liabilities and capital	$ 19,796,588	$ 15,081,132

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Tenant and other receivables, allowance for doubtful accounts	$ 1,636	$ 1,960
Accrued rental income, allowance	3,636	1,571
Unsecured senior notes, discount	14,146	10,472
Unsecured exchangeable senior notes, discount	$ 182	$ 1,653
Redeemable partnership units, series two preferred units outstanding (in units)	666,116	995,997
Redeemable partnership units, common units at redemption value, if converted (in units)	874,168	1,307,083
Redeemable partnership units, series four preferred units outstanding (in units)	360,126	1,221,527
Redeemable partnership units, common units (in units)	15,583,370	16,053,497
Redeemable partnership units, long term incentive units outstanding at redemption value (in units)	1,455,761	1,303,296
General Partners' Capital Account, Units Outstanding (in shares)	1,700,222	1,689,580
Limited Partners' Capital Account, Units Outstanding (in shares)	151,282,879	149,911,629
Series B Cumulative Redeemable Preferred Stock [Member]
Series B Dividend Rate Percentage	5.25%	0.00%
Series B Liquidation Preference Per Unit	$ 2,500.00	$ 0
Series B, Shares Outstanding	80,000	0
Preferred Stock, Shares Issued	80,000	0

Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenue
Base rent	$ 1,675,412	$ 1,457,834	$ 1,376,278
Recoveries from tenants	292,944	228,170	198,083
Parking and other	97,158	89,207	80,496
Total rental revenue	2,065,514	1,775,211	1,654,857
Hotel revenue	40,330	37,915	34,529
Development and management services	29,695	34,060	33,406
Total revenue	2,135,539	1,847,186	1,722,792
Expenses
Rental	742,956	639,088	572,668
Hotel	28,447	28,120	26,128
General and administrative	115,329	90,129	87,101
Transaction costs	1,744	3,653	1,987
Impairment loss	4,401	0	0
Depreciation and amortization	552,589	437,692	421,519
Total expenses	1,445,466	1,198,682	1,109,403
Operating income	690,073	648,504	613,389
Other income (expense)
Income from unconsolidated joint ventures	75,074	49,078	85,896
Gains on consolidation of joint ventures	385,991	0	0
Interest and other income	8,310	10,091	5,358
Gains (losses) from investments in securities	2,911	1,389	(443)
Interest expense	(446,880)	(410,970)	(391,533)
Gains (losses) from early extinguishments of debt	122	(4,453)	(1,494)
Income (Loss) from Continuing Operations	715,601	293,639	311,173
Discontinued operations
Income from discontinued operations	8,022	9,806	10,876
Gain on sale of real estate from discontinued operations	115,459	38,445	0
Gain on forgiveness of debt from discontinued operations	20,736	0	0
Impairment loss from discontinued operations	(2,852)	0	0
Net Income (Loss)	856,966	341,890	322,049
Net income attributable to noncontrolling interests
Noncontrolling interests in property partnerships	(1,347)	(3,792)	(1,558)
Noncontrolling interest - redeemable preferred units	(14,103)	(3,497)	(3,339)
Net income attributable to Boston Properties Limited Partnership	$ 841,516	$ 334,601	$ 317,152
Basic earnings per common unit attributable to Boston Properties Limited Partnership
Income from continuing operations (in dollars per share)	$ 4.14	$ 1.70	$ 1.86
Discontinued operations (in dollars per share)	0.83	0.29	0.07
Net income (in dollars per share)	$ 4.97	$ 1.99	$ 1.93
Weighted average number of common units outstanding (in shares)	169,126	167,769	164,486
Diluted earnings per common unit attributable to Boston Properties Limited Partnership
Income from continuing operations (in dollars per share)	$ 4.14	$ 1.70	$ 1.86
Discontinued operations (in dollars per share)	0.83	0.29	0.06
Diluted Earnings: Net income, Per Unit Amount (in dollars per share)	$ 4.97	$ 1.99	$ 1.92
Weighted average number of common and common equivalent units outstanding (in shares)	169,446	168,360	165,011

Consolidated Statements Of Comprehensive Income - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Statement of Comprehensive Income [Abstract]

Net income

$ 856,966

$ 341,890

$ 322,049

Other comprehensive income:

Amortization of interest rate contracts

^[1]

2,513

2,594

2,595

Other comprehensive income

2,513

2,594

2,595

Comprehensive income

859,479

344,484

324,644

Comprehensive income attributable to noncontrolling interests

(15,450)

(7,289)

(4,897)

Comprehensive income attributable to Boston Properties Limited Partnership

$ 844,029

$ 337,195

$ 319,747

[1]	Amounts reclassified from comprehensive income primarily to interest expense within the Company's Consolidated Statements of Operations.

Consolidated Statements Of Partners' Capital $ in Thousands	USD ($)
Partners' Capital, Beginning Balance at Dec. 31, 2010	$ 2,693,939
Increase (Decrease) in Partners' Capital [Roll Forward]
Contributions	450,412
Net income allocable to general and limited partner units	280,902
Distributions	(300,996)
Accumulated other comprehensive loss	2,298
Unearned compensation	6,537
Conversion of redeemable partnership units	85,498
Adjustment to reflect redeemable partnership units at redemption value	(93,902)
Partners' Capital, Ending Balance at Dec. 31, 2011	3,124,688
Increase (Decrease) in Partners' Capital [Roll Forward]
Contributions	248,863
Net income allocable to general and limited partner units	299,401
Distributions	(346,555)
Accumulated other comprehensive loss	2,321
Unearned compensation	4,364
Conversion of redeemable partnership units	34,621
Adjustment to reflect redeemable partnership units at redemption value	(37,098)
Partners' Capital, Ending Balance at Dec. 31, 2012	3,330,605
Increase (Decrease) in Partners' Capital [Roll Forward]
Contributions	626,568
Net income allocable to general and limited partner units	765,337
Distributions	(748,378)
Accumulated other comprehensive loss	2,261
Unearned compensation	5,002
Conversion of redeemable partnership units	30,291
Adjustment to reflect redeemable partnership units at redemption value	175,485
Partners' Capital, Ending Balance at Dec. 31, 2013	$ 4,187,171

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 856,966	$ 341,890	$ 322,049
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	557,349	445,861	430,961
Non-cash compensation expense	45,155	29,679	29,672
Impairment loss	4,401	0	0
Income from unconsolidated joint ventures	(75,074)	(49,078)	(85,896)
Gains on consolidation of joint ventures	385,991	0	0
Distributions of net cash flow from operations of unconsolidated joint ventures	32,600	47,002	39,851
Losses (gains) from investments in securities	(2,911)	(1,389)	443
Non-cash portion of interest expense	2,649	43,131	54,962
Settlement of accreted debt discount on repurchases of senior notes	(56,532)	(69,499)	(5,601)
Losses (gains) from early extinguishments of debt	(264)	(1,000)	1,494
Gain on sale of real estate from discontinued operations	(115,459)	(38,445)	0
Gain on forgiveness of debt from discontinued operations	(20,736)	0	0
Impairment loss from discontinued operations	2,852	0	0
Change in assets and liabilities:
Cash held in escrows	315	10,272	(9,801)
Tenant and other receivables, net	(443)	23,155	(19,396)
Accrued rental income, net	(59,972)	(77,363)	(79,992)
Prepaid expenses and other assets	12,966	6,990	(39,213)
Accounts payable and accrued expenses	13,108	3,854	6,660
Accrued interest payable	21,302	3,356	6,778
Other liabilities	2,073	1,354	6,569
Tenant leasing costs	(56,428)	(76,821)	(53,212)
Total adjustments	(79,040)	301,059	284,279
Net cash provided by operating activities	777,926	642,949	606,328
Cash flows from investing activities:
Acquisitions of real estate	(522,900)	(788,052)	(112,180)
Construction in progress	(396,835)	(356,397)	(271,856)
Building and other capital improvements	(73,821)	(49,943)	(61,961)
Tenant improvements	(105,425)	(139,662)	(76,320)
Proceeds from the sale of real estate	250,078	61,963	0
Cash recorded upon consolidation	79,468	0	0
Proceeds from land transaction	0	0	43,887
Proceeds from mortgage loan released from (placed in) escrow	0	0	267,500
Deposits on real estate	0	0	10,000
Issuance of notes receivable, net	12,491	(2,049)	(10,442)
Capital contributions to unconsolidated joint ventures	0	(6,214)	(17,970)
Capital distributions from unconsolidated joint ventures	225,862	3,557	140,505
Investments in securities, net	(1,558)	(1,235)	(1,259)
Net cash used in investing activities	(532,640)	(1,278,032)	(90,096)
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	0	1,178,306
Repayments of mortgage notes payable	(80,311)	(253,877)	(1,251,841)
Proceeds from unsecured senior notes	1,194,753	997,790	848,019
Redemption/repurchase of unsecured senior notes	0	(224,261)	0
Redemption/repurchase/exchange of unsecured exchangeable senior notes	(393,468)	(507,434)	(44,586)
Deferred financing costs	(15,195)	(8,468)	(15,970)
Net proceeds from preferred stock issuance	193,623	0	0
Deposit on mortgage loan financing	0	0	(14,500)
Returned deposit on mortgage loan financing	0	0	14,500
Net proceeds from ATM stock issuances	0	247,027	439,037
Net proceeds from equity transactions	(334)	226	9,667
Redemption of preferred units	(43,070)	(18,329)	0
Distributions	(451,118)	(372,899)	(332,597)
Proceeds from sale of ownership interest and contributions from noncontrolling interest in property partnerships	682,617	0	0
Distributions to noncontrolling interest in property partnerships	(9,624)	(5,922)	(2,007)
Net cash provided by (used in) financing activities	1,077,873	(146,147)	828,028
Net increase (decrease) in cash and cash equivalents	1,323,159	(781,230)	1,344,260
Cash and cash equivalents, beginning of year	1,041,978	1,823,208
Cash and cash equivalents, end of year	2,365,137	1,041,978	1,823,208
Supplemental disclosures:
Cash paid for interest	547,973	480,866	386,170
Interest capitalized	68,152	44,278	48,178
Non-cash investing and financing activities:
Additions to real estate included in accounts payable and accrued expenses	19,824	14,059	10,767
real estate and related intangibles recorded upon consolidation	3,356,000	0	0
Debt recorded upon consolidation	2,056,000	0	0
Working capital recorded upon consolidation	177,315	0	0
Noncontrolling Interests recorded upon consolidation	480,861	0	0
investment in unconsolidated joint venture elminated upon consolidation	361,808	0	0
Mortgage note extinguished through foreclosure	25,000	0	0
Real estate transferred upon foreclosure	7,508	0	0
Land improvements contributed by noncontrolling property partnership	4,546	0	0
Mortgage note payable assumed in connection with the acquisition of real estate	0	211,250	143,900
Redeemable noncontrolling interest in property partnerships	0	98,787	0
Preferred units issued in connection with acquisition of real estate	0	79,405	0
Distributions declared but not paid	497,242	110,488	91,901
Stock Issued During Period, Value, Conversion of Convertible Securities	43,834	0	0
Conversions of redeemable partnership units to partners' capital	30,291	34,621	85,498
Issuance of common stock in connection with the exchange of exchangeable senior notes	16,494	5,852	0
Issuance of restricted securities to employees and directors	$ 30,077	$ 26,198	$ 25,087

Organization

12 Months Ended

Dec. 31, 2013

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization

Boston Properties Limited Partnership (the “Company”), a Delaware limited partnership, is the entity through which Boston Properties, Inc., a self-administered and self-managed real estate investment trust (“REIT”), conducts substantially all of its business and owns (either directly or through subsidiaries) substantially all of its assets. Boston Properties, Inc. is the sole general partner of the Company and at December 31, 2013 owned an approximate 89.5% (89.0% at December 31, 2012) general and limited partnership interest in the Company. Partnership interests in the Company are denominated as “common units of partnership interest” (also referred to as “OP Units”), “long term incentive units of partnership interest” (also referred to as “LTIP Units”) or “preferred units of partnership interest” (also referred to as “Preferred Units”). In addition, in February 2011 and February 2012, the Company issued LTIP Units in connection with the granting to employees of outperformance awards (also referred to as “2011 OPP Units” and “2012 OPP Units,” respectively, and collectively as “OPP Units”). In February 2013, the Company issued LTIP Units in connection with the granting to employees of 2013 MYLTIP Units (“2013 MYLTIP Units”). Because the rights, preferences and privileges of OPP Units and 2013 MYLTIP Units differ from other LTIP Units granted to employees as part of the annual compensation process, unless specifically noted otherwise, all references to LTIP Units exclude OPP Units and 2013 MYLTIP Units (See Notes 11 and 17).

Unless specifically noted otherwise, all references to OP Units exclude units held by Boston Properties, Inc. A holder of an OP Unit may present such OP Unit to the Company for redemption at any time (subject to restrictions agreed upon at the time of issuance of OP Units to particular holders that may restrict such redemption right for a period of time, generally one year from issuance). Upon presentation of an OP Unit for redemption, the Company is obligated to redeem such OP Unit for cash equal to the value of a share of common stock of Boston Properties, Inc. (“Common Stock”) at such time. In lieu of a cash redemption, Boston Properties, Inc. may elect to acquire such OP Unit for one share of Common Stock. Because the number of shares of Common Stock outstanding at all times equals the number of OP Units that Boston Properties, Inc. owns, one share of Common Stock is generally the economic equivalent of one OP Unit, and the quarterly distribution that may be paid to the holder of an OP Unit equals the quarterly dividend that may be paid to the holder of a share of Common Stock. An LTIP Unit is generally the economic equivalent of a share of restricted common stock of Boston Properties, Inc. LTIP Units, whether vested or not, will receive the same quarterly per unit distributions as OP Units, which equal per share dividends on Common Stock (See Note 12).

At December 31, 2013, there were three series of Preferred Units outstanding (i.e., Series Two Preferred Units, Series Four Preferred Units and Series B Preferred Units).

•

The Series Two Preferred Units bear a distribution that is set in accordance with an amendment to the partnership agreement of the Company. Each Series Two Preferred Unit may also be converted into approximately 1.312336 OP Units or redeemed for $50.00 of cash at the election of the holder thereof or the Company in accordance with the terms and conditions set forth in the applicable amendment to the partnership agreement (See Note 11).


•	The Series Four Preferred Units are not convertible into or exchangeable for any common equity of the Company or Boston Properties, Inc., have a per unit liquidation preference of $50.00 and are entitled to receive quarterly distributions of $0.25 per unit (or an annual rate of 2.00%) (See Note 11).

•

The Series B Preferred Units were issued to Boston Properties, Inc. on March 27, 2013 in connection with Boston Properties, Inc.'s issuance of 80,000 shares of 5.25% Series B Cumulative Redeemable Preferred Stock (the "Series B Preferred Stock"). Boston Properties, Inc. contributed the net proceeds from the offering to the Company in exchange for 80,000 Series B Preferred Units having terms and preferences generally mirroring those of the Series B Preferred Stock (See Note 12).

All references herein to the Company refer to Boston Properties Limited Partnership and its consolidated subsidiaries, collectively, unless the context otherwise requires.

Properties

At December 31, 2013, the Company owned or had interests in a portfolio of 175 commercial real estate properties (the “Properties”) aggregating approximately 44.4 million net rentable square feet, including nine properties under construction totaling approximately 2.9 million net rentable square feet. In addition, the Company has structured parking for approximately 45,234 vehicles containing approximately 15.4 million square feet. At December 31, 2013, the Properties consist of:


•	167 office properties, including 128 Class A office properties (including eight properties under construction) and 39 Office/Technical properties;


•	one hotel;


•	four retail properties; and


•	three residential properties (including one property under construction).

The Company owns or controls undeveloped land parcels totaling approximately 503.6 acres.

The Company considers Class A office properties to be centrally located buildings that are professionally managed and maintained, attract high-quality tenants and command upper-tier rental rates, and that are modern structures or have been modernized to compete with newer buildings. The Company considers Office/Technical properties to be properties that support office, research and development, laboratory and other technical uses. The Company’s definitions of Class A Office and Office/Technical properties may be different than those used by other companies. Net rentable square feet amounts are unaudited.

Basis of Presentation

Boston Properties, Inc. does not have any other significant assets, liabilities or operations, other than its investment in the Company, nor does it have employees of its own. The Company, not Boston Properties, Inc., executes all significant business relationships. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities ("VIE"s) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income.

- Definition

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

+ References

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+ Details

Summary Of Significant Accounting Policies

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Basis Of Presentation And Summary Of Significant Accounting Policies

Real Estate

Upon acquisitions of real estate that constitutes a business, which includes the consolidation of previously unconsolidated joint ventures, the Company assesses the fair value of acquired tangible and intangible assets (including land, buildings, tenant improvements, “above-” and “below-market” leases, leasing and assumed financing origination costs, acquired in-place leases, other identified intangible assets and assumed liabilities, and allocates the purchase price to the acquired assets and assumed liabilities, including land and buildings as if vacant. The Company assesses and considers fair value based on estimated cash flow projections that utilize discount and/or capitalization rates that it deems appropriate, as well as available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known and anticipated trends, and market and economic conditions. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant. The Company also considers an allocation of purchase price of other acquired intangibles, including acquired in-place leases that may have a customer relationship intangible value, including (but not limited to) the nature and extent of the existing relationship with the tenants, the tenant’s credit quality and expectations of lease renewals. Based on its acquisitions to date, the Company’s allocation to customer relationship intangible assets has been immaterial.

The Company records acquired “above-” and “below-market” leases at their fair values (using a discount rate which reflects the risks associated with the leases acquired) equal to the difference between (1) the contractual amounts to be paid pursuant to each in-place lease and (2) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the initial term plus the term of any below-market fixed rate renewal options for below- market leases. Acquired “above-” and “below-market” lease values have been reflected within Prepaid Expenses and Other Assets and Other Liabilities, respectively, in the Company's Consolidated Balance Sheets. Other intangible assets acquired include amounts for in-place lease values that are based on the Company’s evaluation of the specific characteristics of each tenant's lease. Factors to be considered include estimates of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, the Company considers leasing commissions, legal and other related expenses.

Management reviews its long-lived assets for impairment following the end of each quarter and when there is an event or change in circumstances that indicates an impairment in value. An impairment loss is recognized if the carrying amount of its assets is not recoverable and exceeds its fair value. If such criteria are present, an impairment loss is recognized based on the excess of the carrying amount of the asset over its fair value. The evaluation of anticipated cash flows is highly subjective and is based in part on assumptions regarding future occupancy, rental rates and capital requirements that could differ materially from actual results in future periods. Since cash flows on properties considered to be “long-lived assets to be held and used” are considered on an undiscounted basis to determine whether an asset has been impaired, the Company’s established strategy of holding properties over the long term directly decreases the likelihood of recording an impairment loss. If the Company’s strategy changes or market conditions otherwise dictate an earlier sale date, an impairment loss may be recognized and such loss could be material. If the Company determines that impairment has occurred, the affected assets must be reduced to their fair value, less cost to sell.

Accounting Standards Codification (“ASC”) ASC 360 "Property Plant and Equipment" requires that qualifying assets and liabilities and the results of operations that have been sold, or otherwise qualify as “held for sale,” be presented as discontinued operations in all periods presented if the property operations are expected to be eliminated and the Company will not have significant continuing involvement following the sale. The components of the property’s net income that is reflected as discontinued operations include the net gain (or loss) upon the disposition of the property held for sale, operating results, depreciation and interest expense (if the property is subject to a secured loan). The Company generally considers assets to be “held for sale” when the transaction has been approved by Boston Properties, Inc.’s Board of Directors, or a committee thereof, and there are no known significant contingencies relating to the sale, such that the property sale within one year is considered probable. Following the classification of a property as “held for sale,” no further depreciation is recorded on the assets, and the asset is written down to the lower of carrying value or fair market value, less cost to sell.

Real estate is stated at depreciated cost. A variety of costs are incurred in the acquisition, development and leasing of properties. The cost of buildings and improvements includes the purchase price of property, legal fees and other acquisition costs. The Company expenses costs that it incurs to effect a business combination such as legal, due diligence and other closing related costs. Costs directly related to the development of properties are capitalized. Capitalized development costs include interest, internal wages, property taxes, insurance, and other project costs incurred during the period of development. After the determination is made to capitalize a cost, it is allocated to the specific component of a project that is benefited. Determinations of when a development project commences and capitalization begins, and when a development project is substantially complete and held available for occupancy and capitalization must cease, involve a degree of judgment. The Company’s capitalization policy on development properties is guided by guidance in ASC 835-20 “Capitalization of Interest” and ASC 970 “Real Estate – General.” The costs of land and buildings under development include specifically identifiable costs. The capitalized costs include pre-construction costs necessary to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. The Company begins the capitalization of costs during the pre-construction period, which it defines as activities that are necessary to the development of the property. The Company considers a construction project as substantially completed and held available for occupancy upon the completion of tenant improvements, but no later than one year from cessation of major construction activity. The Company ceases capitalization on the portion (1) substantially completed and (2) occupied or held available for occupancy, and capitalizes only those costs associated with the portion under construction, or if activities necessary for the development of the property have been suspended. Interest costs capitalized for the years ended December 31, 2013, 2012 and 2011 were $68.2 million, $44.3 million and $48.2 million, respectively. Salaries and related costs capitalized for the years ended December 31, 2013, 2012 and 2011 were $7.7 million, $7.1 million and $6.5 million, respectively.

Expenditures for repairs and maintenance are charged to operations as incurred. Significant betterments are capitalized. When assets are sold or retired, their costs and related accumulated depreciation are removed from the accounts with the resulting gains or losses reflected in net income or loss for the period.

The Company computes depreciation and amortization on properties using the straight-line method based on estimated useful asset lives. In accordance with ASC 805, the Company allocates the acquisition cost of real estate to its components and depreciates or amortizes these assets (or liabilities) over their useful lives. The amortization of acquired “above-” and “below-market” leases and acquired in-place leases is recorded as an adjustment to revenue and depreciation and amortization, respectively, in the Consolidated Statements of Operations.

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:




Land improvements		25 to 40 years
Buildings and improvements		10 to 40 years
Tenant improvements		Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment		3 to 7 years

Cash and Cash Equivalents

Cash and cash equivalents consist of cash on hand and investments with maturities of three months or less from the date of purchase. The majority of the Company’s cash and cash equivalents are held at major commercial banks which may at times exceed the Federal Deposit Insurance Corporation limit of $250,000. The Company has not experienced any losses to date on its invested cash.

Cash Held in Escrows

Escrows include amounts established pursuant to various agreements for security deposits, property taxes, insurance and other costs.

Investments in Securities

The Company accounts for investments in trading securities at fair value, with gains or losses resulting from changes in fair value recognized currently in earnings. The designation of trading securities is generally determined at acquisition. The Company maintains a deferred compensation plan that is designed to allow officers of the Company to defer a portion of their current income on a pre-tax basis and receive a tax-deferred return on these deferrals. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2013 and 2012, the Company had maintained approximately $16.6 million and $12.2 million, respectively, in a separate account, which is not restricted as to its use. The Company recognized gains (losses) of approximately $2.9 million, $1.4 million and $(0.4) million on its investments in the account associated with the Company’s deferred compensation plan during the years ended December 31, 2013, 2012 and 2011, respectively.

Tenant and Other Receivables

Tenant and other accounts receivable, other than accrued rents receivable, are expected to be collected within one year.

Deferred Charges

Deferred charges include leasing costs and financing fees. Leasing costs include an allocation for acquired intangible in-place lease values and direct and incremental fees and costs incurred in the successful negotiation of leases, including brokerage, legal, internal leasing employee salaries and other costs which have been deferred and are being amortized on a straight-line basis over the terms of the respective leases. Internal leasing salaries and related costs capitalized for the years ended December 31, 2013, 2012 and 2011 were $5.1 million, $5.6 million and $4.4 million, respectively. External fees and costs incurred to obtain long-term financing have been deferred and are being amortized over the terms of the respective loans and are included within interest expense. Unamortized financing and leasing costs are charged to expense upon the early repayment or significant modification of the financing or upon the early termination of the lease, respectively. Fully amortized deferred charges are removed from the books upon the expiration of the lease or maturity of the debt.

Investments in Unconsolidated Joint Ventures

The Company consolidates variable interest entities (VIEs) in which it is considered to be the primary beneficiary. VIEs are entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or that the holders of the equity investment at risk do not have a controlling financial interest. The primary beneficiary is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the variable interest entity's performance, and (2) the obligation to absorb losses and right to receive the returns from the variable interest entity that would be significant to the variable interest entity. For ventures that are not VIEs the Company consolidates entities for which it has significant decision making control over the ventures' operations. The Company's judgment with respect to its level of influence or control of an entity involves the consideration of various factors including the form of the Company's ownership interest, its representation in the entity's governance, the size of its investment (including loans), estimates of future cash flows, its ability to participate in policy making decisions and the rights of the other investors to participate in the decision making process and to replace the Company as manager and/or liquidate the venture, if applicable. The Company's assessment of its influence or control over an entity affects the presentation of these investments in the Company's consolidated financial statements. In addition to evaluating control rights, the Company consolidates entities in which the outside partner has no substantive kick-out rights to remove the Company as the managing member.

Accounts of the consolidated entity are included in the accounts of the Company and the non-controlling interest is reflected on the Consolidated Balance Sheets as a component of equity or in temporary equity between liabilities and equity. Investments in unconsolidated joint ventures are recorded initially at cost, and subsequently adjusted for equity in earnings and cash contributions and distributions. Any difference between the carrying amount of these investments on the balance sheet and the underlying equity in net assets is amortized as an adjustment to equity in earnings of unconsolidated joint ventures over the life of the related asset. Under the equity method of accounting, the net equity investment of the Company is reflected within the Consolidated Balance Sheets, and the Company's share of net income or loss from the joint ventures is included within the Consolidated Statements of Operations. The joint venture agreements may designate different percentage allocations among investors for profits and losses; however, the Company's recognition of joint venture income or loss generally follows the joint venture's distribution priorities, which may change upon the achievement of certain investment return thresholds. The Company may account for cash distributions in excess of its investment in an unconsolidated joint venture as income when the Company is not the general partner in a limited partnership and when the Company has neither the requirement nor the intent to provide financial support to the joint venture. The Company's investments in unconsolidated joint ventures are reviewed for impairment periodically and the Company records impairment charges when events or circumstances change indicating that a decline in the fair values below the carrying values has occurred and such decline is other-than-temporary, which is dependent on a number of factors, including the performance of each investment and market conditions.

To the extent that the Company contributes assets to a joint venture, the Company’s investment in the joint venture is recorded at the Company’s cost basis in the assets that were contributed to the joint venture. To the extent that the Company’s cost basis is different than the basis reflected at the joint venture level, the basis difference is amortized over the life of the related asset and included in the Company’s share of equity in net income of the joint venture. In accordance with the provisions of ASC 970-323 “Investments—Equity Method and Joint Ventures” (“ASC 970-323”), the Company will recognize gains on the contribution of real estate to joint ventures, relating solely to the outside partner’s interest, to the extent the economic substance of the transaction is a sale.

Revenue Recognition

Contractual rental revenue is reported on a straight-line basis over the terms of the respective leases. The impact of the straight-line rent adjustment increased revenue by approximately $65.8 million, $77.6 million and $77.0 million for the years ended December 31, 2013, 2012 and 2011, respectively, as the revenue recorded exceeded amounts billed. Accrued rental income, as reported on the Consolidated Balance Sheets, represents cumulative rental income earned in excess of rent payments received pursuant to the terms of the individual lease agreements. The Company maintains an allowance against accrued rental income for future potential tenant credit losses. The credit assessment is based on the estimated accrued rental income that is recoverable over the term of the lease. The Company also maintains an allowance for doubtful accounts for estimated losses resulting from the inability of tenants to make required rent payments. The computation of this allowance is based on the tenants’ payment history and current credit status, as well as certain industry or geographic specific credit considerations. If the Company’s estimates of collectability differ from the cash received, then the timing and amount of the Company’s reported revenue could be impacted. The credit risk is mitigated by the high quality of the Company’s existing tenant base, reviews of prospective tenants’ risk profiles prior to lease execution and consistent monitoring of the Company’s portfolio to identify potential problem tenants.

In accordance with ASC 805, the Company recognizes rental revenue of acquired in-place “above-” and “below-market” leases at their fair values over the terms of the respective leases. The impact of the acquired in-place “above-” and “below-market” leases increased revenue by approximately $28.0 million, $14.6 million and $10.8 million for the years ended December 31, 2013, 2012 and 2011, respectively. The following table summarizes the scheduled amortization of the Company's acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2014	$	23,669	$	61,700
2015	22,758		55,207
2016	20,576		52,461
2017	12,279		40,346
2018	8,637		37,774

Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs are recognized as revenue in the period during which the expenses are incurred. Tenant reimbursements are recognized and presented in accordance with guidance in ASC 605-45 “Principal Agent Considerations” (“ASC 605-45”). ASC 605-45 requires that these reimbursements be recorded on a gross basis, as the Company is generally the primary obligor with respect to purchasing goods and services from third-party suppliers, has discretion in selecting the supplier and has credit risk. The Company also receives reimbursement of payroll and payroll related costs from third parties which the Company reflects on a net basis in accordance with ASC 605-45.

The Company's parking revenues are derived from leases, monthly parking and transient parking. The Company recognizes parking revenue as earned.

The Company’s hotel revenues are derived from room rentals and other sources such as charges to guests for telephone service, movie and vending commissions, meeting and banquet room revenue and laundry services. Hotel revenues are recognized as earned.

The Company receives management and development fees from third parties. Property management fees are recorded and earned based on a percentage of collected rents at the properties under management, and not on a straight-line basis, because such fees are contingent upon the collection of rents. The Company reviews each development agreement and records development fees as earned depending on the risk associated with each project. Profit on development fees earned from joint venture projects is recognized as revenue to the extent of the third party partners’ ownership interest.

Gains on sales of real estate are recognized pursuant to the provisions included in ASC 360-20 “Real Estate Sales” (“ASC 360-20”). The specific timing of a sale is measured against various criteria in ASC 360-20 related to the terms of the transaction and any continuing involvement in the form of management or financial assistance associated with the properties. If the sales criteria for the full accrual method are not met, the Company defers some or all of the gain recognition and accounts for the continued operations of the property by applying the finance, leasing, profit sharing, deposit, installment or cost recovery methods, as appropriate, until the sales criteria are met.

Ground Leases

The Company has non-cancelable ground lease obligations with various initial term expiration dates through 2068. The Company recognizes ground rent expense on a straight-line basis over the terms of the respective ground lease agreements. The future contractual minimum lease payments to be made by the Company as of December 31, 2013, under non-cancelable ground leases which expire on various dates through 2068, are as follows:




Years Ending December 31,	(in thousands)
2014	$	13,184
2015	13,507
2016	13,732
2017	13,963
2018	14,198
Thereafter	899,187

Earnings Per Common Unit

Basic earnings per common unit is computed by dividing net income available to common unitholders, as adjusted for unallocated earnings (if any) of certain securities issued by the Company, by the weighted average number of common units outstanding during the year. Diluted earnings per common unit reflects the potential dilution that could occur from units issuable in connection with awards under Boston Properties, Inc.’s stock-based compensation plans, including upon the exercise of stock options, and conversion of preferred units of the Company.

Fair Value of Financial Instruments

The carrying values of cash and cash equivalents, marketable securities, escrows, receivables, accounts payable, accrued expenses and other assets and liabilities are reasonable estimates of their fair values because of the short maturities of these instruments.

The Company follows the authoritative guidance for fair value measurements when valuing its financial instruments for disclosure purposes. The Company determines the fair value of its unsecured senior notes and unsecured exchangeable senior notes using market prices. The inputs used in determining the fair value of the Company’s unsecured senior notes and unsecured exchangeable senior notes is categorized at a level 1 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company uses quoted market rates to value these instruments. However, the inputs used in determining the fair value could be categorized at a level 2 basis if trading volumes are low. The Company determines the fair value of its mortgage notes payable using discounted cash flow analyses by discounting the spread between the future contractual interest payments and hypothetical future interest payments on mortgage debt based on current market rates for similar securities. In determining the current market rates, the Company adds its estimates of market spreads to the quoted yields on federal government treasury securities with similar maturity dates to its debt. The inputs used in determining the fair value of the Company’s mortgage notes payable and mezzanine notes payable are categorized at a level 3 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company considers the rates used in the valuation techniques to be unobservable inputs.

Because the Company’s valuations of its financial instruments are based on these types of estimates, the actual fair values of its financial instruments may differ materially if the Company’s estimates do not prove to be accurate. The following table presents the aggregate carrying value of the Company’s indebtedness and the Company’s corresponding estimate of fair value as of December 31, 2013 and December 31, 2012 (in thousands):



	December 31, 2013					December 31, 2012
	Carrying Amount			Estimated Fair Value		Carrying Amount			Estimated Fair Value
Mortgage notes payable	$	4,449,734		$	4,545,283	$	3,102,485		$	3,256,940
Mezzanine notes payable	311,040			311,064		—			—
Unsecured senior notes	5,835,854			6,050,517		4,639,528			5,162,486
Unsecured exchangeable senior notes	744,880		(1)	750,266		1,170,356		(1)	1,278,554
Total	$	11,341,508		$	11,657,130	$	8,912,369		$	9,697,980

_____________


(1)	Includes the net adjustment for the equity component allocation totaling approximately $2.4 million and $25.5 million at December 31, 2013 and December 31, 2012, respectively.

Derivative Instruments and Hedging Activities

Derivative instruments and hedging activities require management to make judgments on the nature of its derivatives and their effectiveness as hedges. These judgments determine if the changes in fair value of the derivative instruments are reported in the Consolidated Statements of Operations as a component of net income or as a component of comprehensive income and as a component of equity on the consolidated balance sheets. While management believes its judgments are reasonable, a change in a derivative’s effectiveness as a hedge could materially affect expenses, net income and equity. The Company accounts for the effective portion of changes in the fair value of a derivative in other comprehensive income (loss) and subsequently reclassifies the effective portion to earnings over the term that the hedged transaction affects earnings. The Company accounts for the ineffective portion of changes in the fair value of a derivative directly in earnings.

Income Taxes

The partners are required to report their respective share of the Company’s taxable income or loss on their respective tax returns and are liable for any related taxes thereon. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to the Company’s consolidated taxable REIT subsidiaries. The Company’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. The Company has no uncertain tax positions recognized as of December 31, 2013 and 2012.

The Company owns a hotel property which is managed through a taxable REIT subsidiary. The hotel taxable REIT subsidiary, a wholly owned subsidiary of the Company, is the lessee pursuant to the lease for the hotel property. As lessor, the Company is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of the existing management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, the Company has recorded a tax provision in the Company’s Consolidated Statements of Operations for the years ended December 31, 2013, 2012 and 2011.

The net difference between the tax basis and the reported amounts of the Company’s assets and liabilities is approximately $0.9 billion and $0.1 billion as of December 31, 2013 and 2012, respectively, which is primarily related to the difference in basis of contributed property and accrued rental income.

Certain entities included in the Company’s consolidated financial statements are subject to certain state and local taxes. These taxes are recorded as operating expenses in the accompanying consolidated financial statements.

The following table reconciles GAAP net income attributable to Boston Properties Limited Partnership to taxable income:



	For the year ended December 31,
	2013			2012			2011
	(in thousands)
Net income attributable to Boston Properties Limited Partnership	$	841,516		$	334,601		$	317,152
Straight-line rent adjustments	(82,904		)	(89,982		)	(87,773		)
Book/Tax differences from depreciation and amortization	174,384			106,862			118,728
Book/Tax differences on gains/losses from capital transactions	(138,300		)	(24,958		)	(45,056		)
Book/Tax differences from stock-based compensation	46,935			22,035			937
Other book/tax differences, net	7,835			42,004			50,022
Taxable income	$	849,466		$	390,562		$	354,010

Stock-Based Employee Compensation Plans

At December 31, 2013, Boston Properties, Inc. has a stock-based employee compensation plan. Effective January 1, 2005, the Company adopted early ASC 718 “Compensation – Stock Compensation” (“ASC 718”), which revised the fair value based method of accounting for share-based payment liabilities, forfeitures and modifications of stock-based awards and clarified previous guidance in several areas, including measuring fair value, classifying an award as equity or as a liability and attributing compensation cost to reporting periods.

Use of Estimates in the Preparation of Financial Statements

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. These estimates include such items as depreciation and allowances for doubtful accounts. Actual results could differ from those estimates.

Out-of-Period Adjustment

During the year ended December 31, 2012, the Company recorded additional real estate operating expenses totaling approximately $3.2 million related to the cumulative non-cash straight-line adjustment to the ground rent expense of certain ground leases that were not previously recognized on a straight-line basis. This resulted in the overstatement of real estate operating expenses by approximately $3.2 million during the year ended December 31, 2012 and in the understatement of real estate operating expenses in the aggregate amount of approximately $3.2 million in previous periods. Because this adjustment was not material to the prior years’ consolidated financial statements and the impact of recording the adjustment in the current period is not material to the Company’s consolidated financial statements, the Company recorded the related adjustment during the year ended December 31, 2012.

Reclassifications

The Company has modified the presentation of expenses to operate its San Francisco and Princeton regional offices to reflect the growing activity in its San Francisco region and to have a consistent presentation across the Company. These expenses, which totaled approximately $8.1 million, $7.7 million and $7.5 million for the years ended December 31, 2013, 2012 and 2011, respectively, were previously included in Rental Operating Expenses and are now included in General and Administrative Expenses for all periods presented.

Recent Accounting Pronouncements

In February 2013, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2013-02, "Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income" (“ASU No. 2013-02”). ASU No. 2013-02 requires an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component. In addition, an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income, but only if the amount reclassified is required to be reclassified to net income in its entirety in the same reporting period. For other amounts that are not required to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures that provide additional detail about those amounts. ASU No. 2013-02 is effective prospectively for reporting periods beginning after December 15, 2012. The Company’s adoption of ASU No. 2013-02 did not have a material impact on its consolidated financial statements.

Real Estate

12 Months Ended

Dec. 31, 2013

Real Estate [Abstract]

Real Estate

Real estate consisted of the following at December 31 (in thousands):



	2013			2012
Land	$	4,342,951		$	2,496,547
Land held for future development	297,376			271,189
Buildings and improvements	10,742,370			9,191,497
Tenant improvements	1,617,401			1,435,508
Furniture, fixtures and equipment	25,164			23,441
Construction in progress	1,523,179			1,036,780
Total	18,548,441			14,454,962
Less: Accumulated depreciation	(3,096,910		)	(2,876,983		)
	$	15,451,531		$	11,577,979

Acquisitions

On February 6, 2013, the Company completed the acquisition of 535 Mission Street, a development site, in San Francisco, California for an aggregate purchase price of approximately $71.0 million in cash, including work completed and materials purchased to date. When completed, 535 Mission Street will consist of a 27-story, Class A office tower with approximately 307,000 net rentable square feet of office and retail space. The property is currently under development.

On March 26, 2013, a consolidated joint venture in which the Company has a 95% interest completed the acquisition of a land parcel in San Francisco, California that will support a 60-story, 1.4 million square foot office tower known as Transbay Tower. The purchase price for the land was approximately $192.0 million. On February 7, 2013, the partner in the joint venture issued a notice that it was electing under the joint venture agreement to reduce its nominal ownership interest in the venture from 50% to 5%. On February 26, 2013, the Company issued a notice to the partner electing to proceed with the venture on that basis. As a result, the Company has a 95% nominal interest in and is consolidating the joint venture (See Note 11). The initial phase of the development consisting of building the project to grade is currently under development.

On March 29, 2013, the Company completed the acquisition of a parcel of land located in Reston, Virginia for a purchase price of approximately $27.0 million. The land parcel is commercially zoned for 250,000 square feet of office space.

On April 10, 2013, the Company acquired the Mountain View Research Park and Mountain View Technology Park properties from Boston Properties Office Value-Added Fund, L.P. (the "Value-Added Fund") for an aggregate net purchase price of approximately $233.1 million. Mountain View Research Park is a 16-building complex of Office/Technical properties aggregating approximately 604,000 net rentable square feet. Mountain View Technology Park is a seven-building complex of Office/Technical properties aggregating approximately 135,000 net rentable square feet. The following table summarizes the allocation of the aggregate purchase price of Mountain View Research Park and Mountain View Technology Park at the date of acquisition (in thousands) in accordance with the guidance in ASC 805 "Business Combinations."



Land	$	126,521
Building and improvements	82,451
Tenant improvements	7,326
In-place lease intangibles	23,279
Above-market rents	843
Below-market rents	(7,336		)
Net assets acquired	$	233,084

On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties. 767 Fifth Avenue (the General Motors Building) is a Class A office property totaling approximately 1.8 million net rentable square feet. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that, effective as of May 31, 2013, the Company accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting (See Notes 5 and 11). The following table summarizes the allocation of the aggregate purchase price of 767 Fifth Avenue (the General Motors Building) at the date of consolidation on May 31, 2013 (in thousands) in accordance with the guidance in ASC 805 "Business Combinations."



Real estate and related intangibles recorded upon consolidation
Land	$	1,796,252
Building and improvements	1,447,446
Tenant improvements	85,208
In-place lease intangibles	357,781
Above market rents	101,897
Below market rents	(239,641		)
Above market assumed debt adjustments	(192,943		)
	$	3,356,000
Debt recorded upon consolidation
Mortgage notes payable	$	(1,300,000	)
Mezzanine notes payable	(306,000		)
Members' notes payable	(450,000		)	(1)
	$	(2,056,000	)

Working capital recorded upon consolidation
Cash and cash equivalents	$	79,468
Cash held in escrows	2,403
Tenant and other receivables	7,104
Prepaid expenses and other assets	4,269
Accounts payable and accrued expenses	(2,418		)
Accrued interest payable	(182,369		)	(2)
Other liabilities	(6,304		)
	$	(97,847	)
Noncontrolling interest recorded upon consolidation
Noncontrolling interests	$	(520,000	)
Noncontrolling interests - working capital	39,139
	$	(480,861	)

Net assets recorded upon consolidation	$	721,292

_______________

(1) The Company's member loan totaling $270.0 million eliminates in consolidation.

(2) The Company's share of the accrued interest payable on the members' loans totaling approximately $105.5 million eliminates in consolidation.

Mountain View Research Park and Mountain View Technology Park contributed approximately $16.7 million of revenue and approximately $0.4 million of earnings to the Company for the period from April 10, 2013 through December 31, 2013. 767 Fifth Avenue (the General Motors Building) contributed approximately $168.4 million of revenue and approximately $8.4 million of earnings to the Company for the period from May 31, 2013 through December 31, 2013.

The accompanying unaudited pro forma information for the years ended December 31, 2013 and 2012 is presented as if the operating property acquisitions of (1) Mountain View Research Park and Mountain View Technology Park on April 10, 2013 and the approximately $26.5 million gain on consolidation and (2) 767 Fifth Avenue (the General Motors Building) on May 31, 2013 and the approximately $359.5 million gain on consolidation, had occurred on January 1, 2012. This unaudited pro forma information is based upon the historical consolidated financial statements of the Company and should be read in conjunction with the consolidated financial statements and notes thereto. This pro forma information does not purport to represent what the actual results of operations of the Company would have been had the above occurred, nor do they purport to predict the results of operations of future periods.



Pro Forma (Unaudited)	Year ended December 31,
(in thousands, except per unit data)	2013		2012
Total revenue	$	2,257,098	$	2,149,391
Income from continuing operations	$	314,307	$	642,640
Net income attributable to Boston Properties Limited Partnership	$	452,813	$	710,690
Basic earnings per unit:
Net income per unit attributable to Boston Properties Limited Partnership	$	2.68	$	4.21
Diluted earnings per unit:
Net income per unit attributable to Boston Properties Limited Partnership	$	2.67	$	4.20

Developments

On March 22, 2013, the Company completed and fully placed in-service Two Patriots Park, a Class A office redevelopment project with approximately 256,000 net rentable square feet located in Reston, Virginia.

On April 25, 2013, the Company commenced construction of its 601 Massachusetts Avenue, a Class A office development project totaling approximately 478,000 net rentable square feet located in Washington, DC.

On June 14, 2013, the Company completed and fully placed in-service Seventeen Cambridge Center, a Class A office project with approximately 195,000 net rentable square feet located in Cambridge, Massachusetts.

On July 1, 2013, the Company completed and fully placed in-service its Cambridge Center Connector, a Class A office project with approximately 43,000 net rentable square feet located in Cambridge, Massachusetts.

On October 29, 2013, the Company entered into a lease agreement as landlord with a third-party tenant for a build-to-suit project with approximately 130,000 net rentable square feet of Class A office space located in Princeton, New Jersey.

As of December 31, 2013, the Company has placed in-service approximately 63% of The Avant at Reston Town Center development project comprised of 359 apartment units and retail space aggregating approximately 355,000 square feet located in Reston, Virginia (See Note 20).

As of December 31, 2013, the Company has placed in-service approximately 6% of its 250 West 55th Street development project. When completed, this project will consist of approximately 989,000 net rentable square feet of Class A office space located in New York City.

As of December 31, 2013, the Company has placed in-service approximately 1% of its 680 Folsom Street development project. When completed, this project will consist of approximately 525,000 net rentable square feet of Class A office space located in San Francisco, California.

Dispositions

On February 20, 2013, the foreclosure sale of the Company's Montvale Center property was ratified by the court. As a result of the ratification, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate resulting in the recognition of a gain on forgiveness of debt totaling approximately $20.7 million. The operating results of the property through the date of ratification have been classified as discontinued operations on a historical basis for all periods presented.

On June 28, 2013, the Company completed the sale of its 303 Almaden Boulevard property located in San Jose, California for a sale price of $40.0 million. Net cash proceeds totaled approximately $39.3 million. 303 Almaden Boulevard is a Class A office property totaling approximately 158,000 net rentable square feet. Because the Company entered into the related purchase and sale agreement on March 28, 2013 and the carrying value of the property exceeded its net sale price, the Company recognized an impairment loss totaling approximately $2.9 million during the three months ended March 31, 2013. As a result, there was no loss on sale of real estate recognized during the year ended December 31, 2013. The impairment loss and operating results of this property have been classified as discontinued operations on a historical basis for all periods presented. The sale of this asset caused the Company to reevaluate its strategy for development of its adjacent Almaden land parcel, which can accommodate an approximately 840,000 square feet office complex. Based on a shorter than expected hold period, the Company reduced the carrying value of the land parcel to its estimated fair market value and recognized an impairment loss of approximately $4.4 million during the three months ended March 31, 2013. The Company's estimated fair value, as measured on a non-recurring basis, was based on comparable land sales. The Company has determined that its valuation of the land falls within Level 3 of the fair value hierarchy, as it has utilized significant unobservable inputs in its assessment.

On August 22, 2013, the Company completed the sale of its 1301 New York Avenue property located in Washington, DC for a net contract sale price of approximately $121.7 million. After adjusting for outstanding lease and other transaction costs assumed by the buyer, the gross sale price was approximately $135.0 million. Net cash proceeds totaled approximately$121.5 million, resulting in a gain on sale of approximately $88.6 million. 1301 New York Avenue is a Class A office property totaling approximately 201,000 net rentable square feet. The operating results of the property through the date of sale have been classified as discontinued operations on a historical basis for all periods presented.

On October 9, 2013, the Company completed the sale of a 45% ownership interest in its Times Square Tower property for a gross sale price of $684.0 million in cash. Net cash proceeds totaled approximately $673.1 million, after the payment of transaction costs. In connection with the sale, the Company formed a joint venture with the buyer and will provide customary property management and leasing services to the joint venture. Times Square Tower is an approximately 1,246,000 net rentable square foot Class A office tower located in New York City. The transaction did not qualify as a sale of real estate for financial reporting purposes because the Company continues to control the joint venture and will therefore continue to account for the entity on a consolidated basis in its financial statements. The Company has accounted for the transaction as an equity transaction and has recognized noncontrolling interest in its consolidated balance sheets totaling approximately $243.5 million, which is equal to 45% of the carrying value of the total equity of the property immediately prior to the transaction. The difference between the net cash proceeds received and the noncontrolling interest recognized, which difference totals approximately $429.6 million, has not been reflected as a gain on sale of real estate in the Company’s consolidated statements of operations and has instead been reflected as an increase to partners' capital in the Company’s consolidated balance sheets.

On December 20, 2013, the Company completed the sale of its 10 & 20 Burlington Mall Road property located in Burlington, Massachusetts for a sale price of approximately $30.0 million. Net cash proceeds totaled approximately $29.4 million, resulting in a gain on sale of approximately $21.0 million. 10 & 20 Burlington Mall Road consists of two Class A office properties aggregating approximately 152,000 net rentable square feet. The operating results of the properties through the date of sale have been classified as discontinued operations on a historical basis for all periods presented.

On December 20, 2013, the Company completed the sale of its One Preserve Parkway property located in Rockville, Maryland for a sale price of approximately $61.3 million. Net cash proceeds totaled approximately $59.9 million, resulting in a gain on sale of approximately $5.9 million. One Preserve Parkway is a Class A office property totaling approximately 184,000 net rentable square feet. The operating results of the property through the date of sale have been classified as discontinued operations on a historical basis for all periods presented.

The following table summarizes the income from discontinued operations related to One Preserve Parkway, 10 & 20 Burlington Mall Road, 1301 New York Avenue, 303 Almaden Boulevard, Montvale Center and Bedford Business Park and the related gains on sales of real estate, gain on forgiveness of debt and impairment loss for the years ended December 31, 2013, 2012 and 2011:



	For the year ended December 31,
	2013			2012		2011
	(in thousands)
Total revenue	$	20,138		$	32,607	$	36,734
Expenses
Operating	6,996			12,038		13,818
Depreciation and amortization	4,760			8,169		9,442
Total expenses	11,756			20,207		23,260
Operating income	8,382			12,400		13,474
Other expense
Interest expense	360			2,594		2,598
Income from discontinued operations attributable to Boston Properties Limited Partnership	$	8,022		$	9,806	$	10,876

Gains on sales of real estate from discontinued operations attributable to Boston Properties Limited Partnership	$	115,459		$	38,445	$	—
Gain on forgiveness of debt from discontinued operations attributable to Boston Properties Limited Partnership	$	20,736		$	—	$	—
Impairment loss from discontinued operations attributable to Boston Properties Limited Partnership	$	(2,852	)	$	—	$	—

Deferred Charges

12 Months Ended

Dec. 31, 2013

Deferred Charges [Abstract]

Deferred Charges

4. Deferred Charges

Deferred charges consisted of the following at December 31, (in thousands):



	2013			2012
Leasing costs, including lease related intangibles	$	1,183,204		$	790,740
Financing costs	76,798			90,682
	1,260,002			881,422
Less: Accumulated amortization	(375,552		)	(293,187		)
	$	884,450		$	588,235

The following table summarizes the scheduled amortization of the Company's acquired in-place lease intangibles for each of the five succeeding years (in thousands).



	Acquired In-Place Lease Intangibles
2014	$	91,903
2015	66,716
2016	55,083
2017	41,106
2018	36,306

Investments in Unconsolidated Joint Ventures

12 Months Ended

Dec. 31, 2013

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures

Investments in Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at December 31, 2013:



Entity	Properties	Nominal % Ownership
Square 407 Limited Partnership	Market Square North	50.0	%
The Metropolitan Square Associates LLC	Metropolitan Square	51.0	%
BP/CRF 901 New York Avenue LLC	901 New York Avenue	25.0	%	(1)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.3	%	(2)
RBP Joint Venture LLC	N/A	50.0	%	(3)
Boston Properties Office Value-Added Fund, L.P.	N/A	39.5	%	(4)
Annapolis Junction NFM, LLC	Annapolis Junction	50.0	%	(5)
2 GCT Venture LLC	N/A	60.0	%	(6)
540 Madison Venture LLC	540 Madison Avenue	60.0	%
125 West 55^th Street Venture LLC	N/A	60.0	%	(7)
500 North Capitol LLC	500 North Capitol Street, NW	30.0	%

_______________


(1)	The Company’s economic ownership can increase based on the achievement of certain return thresholds.


(2)	The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land, parking and infrastructure of the project.


(3)	Eighth Avenue and 46th Street was sold on July 19, 2013.


(4)	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of December 31, 2013, the investment is comprised of undistributed cash.


(5)	Comprised of two buildings, one building under construction and two undeveloped land parcels.


(6)	Two Grand Central Tower was sold on October 25, 2011. As of December 31, 2013, the investment is comprised of undistributed cash.


(7)	125 West 55th Street was sold on May 30, 2013. As of December 31, 2013, the investment is comprised of undistributed cash.

Certain of the Company’s joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of its interest in the joint ventures at an agreed upon fair value. Under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners.

The combined summarized balance sheets of the unconsolidated joint ventures are as follows:



	December 31, 2013			December 31, 2012
	(in thousands)
ASSETS
Real estate and development in process, net	$	924,297		$	4,494,971
Other assets	163,149			673,716
Total assets	$	1,087,446		$	5,168,687
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable	$	749,732		$	3,039,922
Other liabilities	28,830			792,888
Members’/Partners’ equity	308,884			1,335,877
Total liabilities and members’/partners’ equity	$	1,087,446		$	5,168,687
Company’s share of equity	$	154,726		$	787,941
Basis differentials (1)	(28,642		)	(128,025		)
Carrying value of the Company’s investments in unconsolidated joint ventures	$	126,084		$	659,916

_______________

(1)

This amount represents the aggregate difference between the Company’s historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from impairment of investments and upon the transfer of assets that were previously owned by the Company into a joint venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level.

The combined summarized statements of operations of the joint ventures are as follows:



	For the year ended December 31,
	2013			2012			2011
	(in thousands)
Total revenue (1)	$	311,548		$	564,205		$	589,294
Expenses
Operating	105,319			162,665			170,404
Depreciation and amortization	86,088			163,134			190,437
Impairment losses	—			—			40,468
Total expenses	191,407			325,799			401,309
Operating income	120,141			238,406			187,985
Other income (expense)
Interest expense	(112,535		)	(224,645		)	(228,494		)
Losses from early extinguishments of debt	(1,677		)	—			—
Income (loss) from continuing operations	5,929			13,761			(40,509		)
Gains on sales of real estate	14,207			990			—
Net income (loss)	$	20,136		$	14,751		$	(40,509	)

Company’s share of net income (loss)	$	4,612		$	6,863		$	(25,374	)
Gains on sales of real estate	54,501			—			46,166
Basis differential	(1,017		)	1,732			27,226
Elimination of inter-entity interest on partner loan	16,978			40,483			37,878
Income from unconsolidated joint ventures	$	75,074		$	49,078		$	85,896
Gains on consolidation of joint ventures	$	385,991		$	—		$	—

_______________

(1)

Includes straight-line rent adjustments of $7.8 million, $12.0 million and $21.9 million for the years ended December 31, 2013, 2012 and 2011, respectively. Includes net below-market rent adjustments of $33.7 million, $91.1 million and $120.3 million for the years ended December 31, 2013, 2012 and 2011, respectively. Total revenue for the year ended December 31, 2012 includes termination income totaling approximately $19.6 million (of which the Company's share is approximately $11.8 million) related to a lease termination with a tenant at 767 Fifth Avenue (The General Motors Building).

On February 28, 2013, a joint venture in which the Company has a 50% interest completed and fully placed in-service Annapolis Junction Building Six, a Class A office property with approximately 119,000 net rentable square feet located in Annapolis, Maryland.

On March 31, 2013, a joint venture in which the Company has a 30% interest completed and fully placed in-service 500 North Capitol Street, NW, a Class A office redevelopment project with approximately 231,000 net rentable square feet located in Washington, DC.

On April 4, 2013, a joint venture in which the Company has a 50% interest obtained construction financing collateralized by its Annapolis Junction Building Seven development project located in Annapolis, Maryland totaling $22.0 million. The construction financing bears interest at a variable rate equal to LIBOR plus 1.65% per annum and matures on April 4, 2016, with two, one-year extension options, subject to certain conditions.

On April 10, 2013, the Company acquired the Mountain View Research Park and Mountain View Technology Park properties from its Value-Added Fund for an aggregate net purchase price of approximately $233.1 million. In conjunction with the acquisition, the Value-Added Fund repaid the mortgage loans collateralized by the Mountain View Research Park and Mountain View Technology Park properties totaling approximately $90.0 million and $20.0 million, respectively, as well as the outstanding loans payable to the Company totaling approximately $8.6 million and $3.7 million, respectively. The Mountain View Research Park and Mountain View Technology Park mortgage loans bore interest at variable rates equal to LIBOR plus 2.00% per annum and LIBOR plus 2.50% per annum, respectively, and were scheduled to mature on May 31, 2014 and November 22, 2014, respectively. The joint venture recognized a loss on early extinguishment of debt totaling approximately $0.4 million, of which the Company's share was approximately $0.2 million, consisting of the write-off of unamortized deferred financing costs. Prior to the acquisition, the Company's ownership interest in the properties was approximately 39.5%. As a result of the acquisition, the Company owns 100% of the properties and is accounting for them on a consolidated basis (See Note 3). The Company had previously recognized an impairment loss on its investment in the unconsolidated joint venture. As a result, the Company recognized a gain on its investment of approximately $26.5 million, which is included within gains on consolidation of joint ventures in the Company's consolidated statements of operations.

On May 30, 2013, a joint venture in which the Company has a 60% interest completed the sale of its 125 West 55th Street property located in New York City for a sale price of $470.0 million, including the assumption by the buyer of the mortgage loan collateralized by the property totaling approximately $198.6 million. The mortgage loan bore interest at a fixed rate of 6.09% per annum and was scheduled to mature on March 10, 2020. Net cash proceeds totaled approximately $253.7 million, of which the Company's share was approximately $152.2 million, after the payment of transaction costs. 125 West 55th Street is a Class A office property totaling approximately 588,000 net rentable square feet. The Company had previously recognized an impairment loss on its investment in the unconsolidated joint venture. As a result, the Company recognized a gain on sale of real estate totaling approximately $43.2 million, which is included within income from unconsolidated joint ventures in the Company's consolidated statements of operations.

On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that the Company now accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting (See Note 3). Upon consolidation, the Company recognized a non-cash gain on its investment of approximately $359.5 million, which is included within gains on consolidation of joint ventures in the Company's consolidated statements of operations.

On May 31, 2013, a joint venture in which the Company has a 30% interest refinanced its construction loan collateralized by 500 North Capitol Street, NW located in Washington, DC. The construction loan totaling approximately $90.6 million bore interest at a variable rate equal to LIBOR plus 1.65% per annum and was scheduled to mature on October 14, 2014. The joint venture recognized a loss on early extinguishment of debt totaling approximately $1.0 million, of which the Company's share was approximately $0.3 million, consisting of the write-off of unamortized deferred financing costs. The new mortgage loan totaling $105.0 million requires interest only payments at a fixed interest rate of 4.15% per annum and matures on June 6, 2023.

On June 5, 2013, a joint venture in which the Company has a 60% interest refinanced its mortgage loans collateralized by 540 Madison Avenue located in New York City. The mortgage loans aggregating approximately $118.0 million bore interest at a weighted-average fixed rate of 5.20% per annum and were scheduled to mature on July 11, 2013. The joint venture recognized a loss on early extinguishment of debt totaling approximately $0.3 million, of which the Company's share was approximately $0.2 million, related to the acceleration of the remaining balance of the historical fair value debt adjustment, which was the result of purchase accounting. The new mortgage loan totaling $120.0 million requires interest only payments at a variable rate equal to LIBOR plus 1.50% per annum and matures on June 5, 2018.

On July 19, 2013, a joint venture in which the Company has a 50% interest completed the sale of its Eighth Avenue and 46th Street project located in New York City for an imputed sale price of $45.0 million. The Eighth Avenue and 46th Street project is comprised of an assemblage of land parcels and air-rights. Net cash proceeds to the Company totaled approximately $21.8 million, after the payment of transaction costs. The joint venture had previously recognized an impairment loss on the property. As a result, the joint venture recognized a gain on sale of real estate totaling approximately $12.6 million, of which the Company's share was approximately $11.3 million. The Company's share of the gain on sale of real estate is reflective of the Company's share of the net proceeds from the imputed sale price and is included within income from unconsolidated joint ventures in the Company's consolidated statements of operations.

On September 26, 2013, a joint venture in which the Company has a 50% interest entered into a lease agreement for its Annapolis Junction Building Seven development project. Annapolis Junction Building Seven when completed will consist of a Class A office property with approximately 125,000 net rentable square feet located in Annapolis, Maryland.

On October 29, 2013, a joint venture in which the Company has a 50% interest exercised an option to extend the maturity date to November 17, 2014 of the construction financing collateralized by its Annapolis Junction Building Six property. The construction financing totaling approximately $14.0 million bears interest at a variable rate equal to LIBOR plus 1.65% per annum and was scheduled to mature on November 17, 2013. Annapolis Junction Building Six is a Class A office property with approximately 119,000 net rentable square feet located in Annapolis, Maryland.

Mortgage Notes Payable

12 Months Ended

Dec. 31, 2013

Loans Payable [Abstract]

Mortgage Notes Payable

The Company had outstanding mortgage notes payable totaling approximately $4.4 billion and $3.1 billion as of December 31, 2013 and 2012, respectively, each collateralized by one or more buildings and related land included in real estate assets. The mortgage notes payable are generally due in monthly installments and mature at various dates through April 10, 2022.

Fixed rate mortgage notes payable totaled approximately $4.4 billion and $3.1 billion at December 31, 2013 and 2012, respectively, with contractual interest rates ranging from 4.75% to 7.69% per annum at December 31, 2013 and 4.75% to 9.93% per annum at December 31, 2012 (with weighted-averages of 5.70% (excluding the mezzanine notes payable) and 5.65% at December 31, 2013 and 2012, respectively).

There were no variable rate mortgage loans at December 31, 2013 and December 31, 2012. As of December 31, 2013 and 2012, the LIBOR rate was 0.17% and 0.21%, respectively.

On February 5, 2013, the Company used available cash to repay the mortgage loan collateralized by its Kingstowne One property located in Alexandria, Virginia totaling approximately $17.0 million. The mortgage loan bore interest at a fixed rate of 5.96% per annum and was scheduled to mature on May 5, 2013. There was no prepayment penalty.

On April 1, 2013, the Company used available cash to repay the mortgage loan collateralized by its 140 Kendrick Street property located in Needham, Massachusetts totaling approximately $47.6 million. The mortgage loan bore interest at a fixed rate of 7.51% per annum and was scheduled to mature on July 1, 2013. There was no prepayment penalty. The Company recognized a gain on early extinguishment of debt totaling approximately $0.3 million related to the acceleration of the remaining balance of the historical fair value debt adjustment, which was the result of purchase accounting.

On May 31, 2013, in conjunction with the consolidation of the Company's 767 Venture, LLC joint venture (the entity that owns 767 Fifth Avenue (the General Motors Building), the Company recorded mortgage loans collateralized by the property aggregating $1.3 billion and mezzanine loans aggregating $306.0 million. The mortgage loans require interest-only payments at a weighted-average fixed interest rate of 5.95% per annum and mature on October 7, 2017. The mezzanine loans require interest-only payments at a weighted-average fixed interest rate of 6.02% per annum and mature on October 7, 2017. The mortgage loans and mezzanine loans were recorded at their fair values aggregating approximately $1.5 billion and $311.7 million, respectively, using weighted-average effective interest rates of approximately 2.44% and 5.53% per annum, respectively. In addition, in conjunction with the consolidation, the Company recorded loans payable to the joint venture's partners totaling $450.0 million and related accrued interest payable totaling approximately $175.8 million. The member loans bear interest at a fixed rate of 11.0% per annum and mature on June 9, 2017. The member loans consist of the portion of the original purchase price for the property that was financed with loans from the joint venture's partners on a pro rata basis. The Company has eliminated in consolidation its member loan totaling $270.0 million and its share of the related accrued interest payable of approximately $114.5 million at December 31, 2013. The remaining notes payable to the outside joint venture partners and related accrued interest payable totaling $180.0 million and approximately $76.4 million as of December 31, 2013 have been reflected as Outside Members' Notes Payable and within Accrued Interest Payable, respectively, on the Consolidated Balance Sheets (See Note 3). The related interest expense from the Outside Members' Notes Payable totaling approximately $16.0 million for the period from May 31, 2013 through December 31, 2013 is fully allocated to the outside joint venture partners as an adjustment to Noncontrolling Interests in Property Partnerships in the Company's Consolidated Statements of Operations.

Four mortgage loans totaling approximately $2.2 billion at December 31, 2013 and five mortgage loans totaling approximately $951.5 million at December 31, 2012 have been accounted for at their fair values on the dates the mortgage loans were assumed. The impact of recording the mortgage loans at fair value resulted in a decrease to interest expense of approximately $34.4 million, $7.0 million and $9.2 million for the years ended December 31, 2013, 2012 and 2011, respectively. The cumulative liability related to the fair value adjustments was $191.2 million and $38.6 million at December 31, 2013 and 2012, respectively, and is included in mortgage notes payable in the Consolidated Balance Sheets.

Contractual aggregate principal payments of mortgage notes payable at December 31, 2013 are as follows:



	Principal Payments
	(in thousands)
2014	$	87,759
2015	26,182
2016	608,879
2017	2,821,750
2018	18,633
Thereafter	695,327
Total aggregate principal payments	4,258,530
Unamortized balance of historical fair value adjustments	191,204
Total carrying value of mortgage notes payable	$	4,449,734

Unsecured Senior Notes

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Unsecured Senior Notes

The following summarizes the unsecured senior notes outstanding as of December 31, 2013 (dollars in thousands):



	Coupon/ Stated Rate		Effective Rate(1)		Principal Amount			Maturity Date(2)
12 Year Unsecured Senior Notes	5.625	%	5.693	%	$	300,000		April 15, 2015
12 Year Unsecured Senior Notes	5.000	%	5.194	%	250,000			June 1, 2015
10 Year Unsecured Senior Notes	5.875	%	5.967	%	700,000			October 15, 2019
10 Year Unsecured Senior Notes	5.625	%	5.708	%	700,000			November 15, 2020
10 Year Unsecured Senior Notes	4.125	%	4.289	%	850,000			May 15, 2021
7 Year Unsecured Senior Notes	3.700	%	3.853	%	850,000			November 15, 2018
11 Year Unsecured Senior Notes	3.850	%	3.954	%	1,000,000			February 1, 2023
10.5 Year Unsecured Senior Notes	3.125	%	3.279	%	500,000			September 1, 2023
10.5 Year Unsecured Senior Notes	3.800	%	3.916	%	700,000			February 1, 2024

Total principal					5,850,000
Net unamortized discount					(14,146		)
Total					$	5,835,854

_______________


(1)	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.


(2)	No principal amounts are due prior to maturity.

The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60%, (2) a secured debt leverage ratio not to exceed 50%, (3) an interest coverage ratio of greater than 1.50, and (4) an unencumbered asset value of not less than 150% of unsecured debt. At December 31, 2013, the Company was in compliance with each of these financial restrictions and requirements.

On April 11, 2013, the Company completed a public offering of $500.0 million in aggregate principal amount of its 3.125% senior unsecured notes due 2023. The notes were priced at 99.379% of the principal amount to yield an effective rate (including financing fees) of 3.279% to maturity. The notes will mature on September 1, 2023, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $492.5 million after deducting underwriting discounts and transaction expenses.

On June 27, 2013, the Company completed a public offering of $700.0 million in aggregate principal amount of its 3.800% senior unsecured notes due 2024. The notes were priced at 99.694% of the principal amount to yield an effective rate (including financing fees) of 3.916% to maturity. The notes will mature on February 1, 2024, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $691.9 million after deducting the underwriting discount and transaction expenses.

Unsecured Exchangeable Senior Notes

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Unsecured Exchangeable Senior Notes

The following summarizes the unsecured exchangeable senior notes outstanding as of December 31, 2013 (dollars in thousands):



	Coupon/ Stated Rate		Effective Rate(1)		Exchange Rate		Principal Amount			First Optional Redemption Date by the Company	Maturity Date
3.625% Exchangeable Senior Notes	3.625	%	4.037	%	8.6974	(2)	$	747,500		N/A	February 15, 2014
Net unamortized discount							(182		)
Adjustment for the equity component allocation, net of accumulated amortization							(2,438		)
Total							$	744,880

_______________


(1)	Yield on issuance date including the effects of discounts on the notes but excluding the effects of the adjustment for the equity component allocation.

(2)

The initial exchange rate is 8.5051 shares per $1,000 principal amount of the notes (or an initial exchange price of approximately $117.58 per share of Boston Properties, Inc.’s common stock). In addition, the Company entered into capped call transactions with affiliates of certain of the initial purchasers, which are intended to reduce the potential dilution upon future exchange of the notes. The capped call transactions were intended to increase the effective exchange price to the Company of the notes from $117.58 to approximately $137.17 per share (subject to adjustments), representing an overall effective premium of approximately 40% over the closing price on August 13, 2008 of $97.98 per share of Boston Properties, Inc.’s common stock. The net cost of the capped call transactions was approximately $44.4 million. In connection with the special dividend declared on November 27, 2013, the exchange rate of 8.5051 was adjusted to 8.6974 shares per $1,000 principal amount of notes effective as of December 31, 2013, resulting in an exchange price of approximately $114.98 per share of Boston Properties, Inc.'s common stock. As of December 31, 2013, the effective exchange price was $130.21 per share. The Company repaid the notes on February 18, 2014 (See Note 20).

ASC 470-20 requires the liability and equity components of convertible debt instruments that may be settled in cash upon conversion (including partial cash settlement) to be separately accounted for in a manner that reflects the issuer’s nonconvertible debt borrowing rate. ASC 470-20 requires that the initial proceeds from the sale of the Company’s $862.5 million of 2.875% exchangeable senior notes due 2037 (all of which had been redeemed/repurchased as of December 31, 2012), $450.0 million of 3.75% exchangeable senior notes due 2036 (all of which have been redeemed/repurchased as of December 31, 2013) and $747.5 million of 3.625% exchangeable senior notes due 2014 (see Note 20) be allocated between a liability component and an equity component in a manner that reflects interest expense at the interest rate of similar nonconvertible debt that could have been issued by the Company at such time. The Company measured the fair value of the debt components of the 2.875%, 3.75% and 3.625% exchangeable senior notes for the periods presented based on effective interest rates of 5.630%, 5.958% and 6.555%, respectively. The aggregate carrying amount of the debt component was approximately $744.9 million and $1.17 billion (net of the equity component allocation adjustment of approximately $2.4 million and $25.5 million) at December 31, 2013 and December 31, 2012, respectively. As a result, the Company attributed an aggregate of approximately $230.3 million of the proceeds to the equity component of the notes, which represents the excess proceeds received over the fair value of the notes at the date of issuance. The equity component of the notes has been reflected within Partners’ Capital in the Consolidated Balance Sheets. The Company reclassified approximately $1.0 million of deferred financing costs to Partners’ Capital, which represented the costs attributable to the equity components of the notes. The carrying amount of the equity component was approximately $91.9 million and $148.5 million at December 31, 2013 and December 31, 2012, respectively. The resulting debt discount has been amortized over the period during which the debt was expected to be outstanding (i.e., through the first optional redemption dates or, in the case of the 2014 notes, the maturity date) as additional non-cash interest expense. The aggregate contractual interest expense was approximately $34.8 million, $48.4 million and $66.3 million for the years ended December 31, 2013, 2012 and 2011, respectively. As a result, the Company reported additional non-cash interest expense of approximately $23.1 million, $29.1 million and $38.8 million for the years ended December 31, 2013, 2012 and 2011, respectively.

On April 15, 2013, the Company announced that holders of its 3.75% Exchangeable Senior Notes due 2036 (the “Notes”) had the right to surrender their Notes for purchase by the Company (the “Put Right”) on May 18, 2013. On April 15, 2013, the Company also announced that it had issued a notice of redemption to the holders of the Notes to redeem, on May 18, 2013 (the “Redemption Date”), all of the Notes outstanding on the Redemption Date. In connection with the notice of redemption, holders of the Notes had the right to exchange their Notes on or prior to May 16, 2013. Notes with respect to which the Put Right was not exercised and that were not surrendered for exchange on or prior to May 16, 2013, were redeemed by the Company at a redemption price equal to 100% of the principal amount of the Notes plus accrued and unpaid interest thereon to, but excluding, the Redemption Date. Based on final information provided to the Company by the trustee for the Notes, no Notes were validly tendered and accepted for purchase in the Put Right. Pursuant to the notice of redemption, an aggregate principal amount of $990,000 of the Notes was redeemed on May 18, 2013. The remaining aggregate principal amount of $449,010,000 of the Notes was surrendered for exchange and, in addition to the repayment of the principal in cash, Boston Properties, Inc. issued an aggregate of 419,116 shares of its common stock in exchange for the Notes (See Note 12). The Company recognized a loss on early extinguishment of debt totaling approximately $0.1 million consisting of transaction costs.

Unsecured Line of Credit	12 Months Ended
Unsecured Line of Credit	Dec. 31, 2013
Unsecured Line of Credit [Abstract]
Unsecured Line of Credit [Text Block]	9. Unsecured Line of Credit On July 26, 2013, the Company amended and restated the revolving credit agreement governing the Company's Unsecured Line of Credit, which, among other things, (1) increased the total commitment from $750.0 million to $1.0 billion, (2) extended the maturity date from June 24, 2014 to July 26, 2018 and (3) reduced the per annum variable interest rates and other fees. The Company may increase the total commitment to $1.5 billion, subject to syndication of the increase and other conditions. At the Company's option, loans outstanding under the Unsecured Line of Credit will bear interest at a rate per annum equal to (1), in the case of loans denominated in Dollars, Euro or Sterling, LIBOR or, in the case of loans denominated in Canadian Dollars, CDOR, in each case, plus a margin ranging from 0.925% to 1.70% based on the Company’s credit rating or (2) an alternate base rate equal to the greatest of (a) the Administrative Agent’s prime rate, (b) the Federal Funds rate plus 0.5% or (c) LIBOR for a one month period plus 1.00%, in each case, plus a margin ranging from 0.0% to 0.70% based on the Company’s credit rating. The Unsecured Line of Credit also contains a competitive bid option that allows banks that are part of the lender consortium to bid to make loan advances to the Company at a reduced interest rate. In addition, the Company is also obligated to pay (1) in quarterly installments a facility fee on the total commitment at a rate per annum ranging from 0.125% to 0.35% based on the Company’s credit rating and (2) an annual fee on the undrawn amount of each letter of credit equal to the LIBOR margin. Based on the Company’s current credit rating, the LIBOR and CDOR margin is 1.00%, the alternate base rate margin is 0.0% and the facility fee is 0.15%. At December 31, 2013 and 2012, there were no amounts outstanding on the Unsecured Line of Credit. The terms of the Unsecured Line of Credit require that the Company maintain a number of customary financial and other covenants on an ongoing basis, including: (1) a leverage ratio not to exceed 60%, however, the leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (2) a secured debt leverage ratio not to exceed 55%, (3) a fixed charge coverage ratio of at least 1.40, (4) an unsecured debt leverage ratio not to exceed 60%, however, the unsecured debt leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (5) an unsecured debt interest coverage ratio of at least 1.75 and (6) limitations on permitted investments. At December 31, 2013, the Company was in compliance with each of these financial and other covenant requirements.

Commitments And Contingencies	12 Months Ended
Commitments And Contingencies	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	Commitments and Contingencies General In the normal course of business, the Company guarantees its performance of services or indemnifies third parties against its negligence. In addition, in the normal course of business, the Company guarantees to certain tenants the obligations of its subsidiaries for the payment of tenant improvement allowances and brokerage commissions in connection with their leases and limited costs arising from delays in delivery of their premises. The Company has letter of credit and performance obligations of approximately $13.9 million related to lender and development requirements. Certain of the Company’s joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of the property or its interest in the joint ventures. Under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners. See also Noncontrolling Interest—Redeemable Interest in Property Partnership in Note 11. In connection with the assumption of 767 Fifth Avenue's (the General Motors Building) secured loan by the Company’s consolidated joint venture, 767 Venture, LLC, the Company guaranteed the consolidated joint venture’s obligation to fund various escrows, including tenant improvements, taxes and insurance in lieu of cash deposits. As of December 31, 2013, the maximum funding obligation under the guarantee was approximately $24.1 million. The Company earns a fee from the joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee. In connection with the mortgage financing collateralized by the Company's John Hancock Tower property located in Boston, Massachusetts, the Company has agreed to guarantee approximately $15.9 million related to its obligation to provide funds for certain tenant re-leasing costs. The mortgage financing matures on January 6, 2017. From time to time, the Company (or the applicable joint venture) has also agreed to guarantee portions of the principal, interest or other amounts in connection with other unconsolidated joint venture borrowings. In addition to the financial guarantees referenced above, the Company has agreed to customary environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, misrepresentation and bankruptcy) on certain of its unconsolidated joint venture loans. Concentrations of Credit Risk Management of the Company performs ongoing credit evaluations of tenants and may require tenants to provide some form of credit support such as corporate guarantees and/or other financial guarantees. Although the Company’s properties are geographically diverse and the tenants operate in a variety of industries, to the extent the Company has a significant concentration of rental revenue from any single tenant, the inability of that tenant to make its lease payments could have an adverse effect on the Company. Some potential losses are not covered by insurance. The Company carries insurance coverage on its properties of types and in amounts and with deductibles that it believes are in line with coverage customarily obtained by owners of similar properties. In response to the uncertainty in the insurance market following the terrorist attacks of September 11, 2001, the Federal Terrorism Risk Insurance Act (as amended, “TRIA”) was enacted in November 2002 to require regulated insurers to make available coverage for “certified” acts of terrorism (as defined by the statute). The expiration date of TRIA was extended to December 31, 2014 by the Terrorism Risk Insurance Program Reauthorization Act of 2007 (“TRIPRA”) and the Company can provide no assurance that it will be extended further. Currently, the Company’s property insurance program per occurrence limits are $1.0 billion for its portfolio insurance program, including coverage for acts of terrorism certified under TRIA other than nuclear, biological, chemical or radiological terrorism (“Terrorism Coverage”). The Company also carries $250 million of Terrorism Coverage for 601 Lexington Avenue, New York, New York (“601 Lexington Avenue”) in excess of the $1.0 billion of coverage in the Company’s property insurance program which is provided by IXP, LLC (“IXP”) as a direct insurer. Certain properties, including the General Motors Building located at 767 Fifth Avenue in New York, New York (“767 Fifth Avenue”), are currently insured in separate insurance programs. The property insurance program per occurrence limits for 767 Fifth Avenue are $1.625 billion, including Terrorism Coverage, with $1.375 billion of Terrorism Coverage in excess of $250 million being provided by NYXP, LLC (“NYXP”), as a direct insurer. The Company also currently carries nuclear, biological, chemical and radiological terrorism insurance coverage for acts of terrorism certified under TRIA (“NBCR Coverage”), which is provided by IXP as a direct insurer, for the properties in our portfolio, including 767 Fifth Avenue, but excluding certain other properties owned in joint ventures with third parties or which the Company manages. The per occurrence limit for NBCR Coverage is $1.0 billion. Under TRIA, after the payment of the required deductible and coinsurance, the additional Terrorism Coverage provided by IXP for 601 Lexington Avenue, the NBCR Coverage provided by IXP and the Terrorism Coverage provided by NYXP are backstopped by the Federal Government if the aggregate industry insured losses resulting from a certified act of terrorism exceed a “program trigger.” The program trigger is $100.0 million and the coinsurance is 15%. Under TRIPRA, if the Federal Government pays out for a loss under TRIA, it is mandatory that the Federal Government recoup the full amount of the loss from insurers offering TRIA coverage after the payment of the loss pursuant to a formula in TRIPRA. The Company may elect to terminate the NBCR Coverage if the Federal Government seeks recoupment for losses paid under TRIA, if there is a change in its portfolio or for any other reason. In the event TRIPRA is not extended beyond December 31, 2014, (i) the Company will evaluate alternative approaches to secure coverage for acts of terrorism thereby potentially increasing its overall cost of insurance, (ii) if such insurance is not available at commercially reasonable rates with limits equal to its current coverage or at all, the Company may not continue to have full occurrence limit coverage for acts of terrorism, (iii) the Company may not satisfy the insurance requirements under existing or future debt financings secured by individual properties, (iv) the Company may not be able to obtain future debt financings secured by individual properties and (v) the Company may cancel the insurance policies issued by IXP for the NBCR Coverage and the additional Terrorism Coverage for 601 Lexington Avenue and by NYXP for the Terrorism Coverage for 767 Fifth Avenue. The Company intends to continue to monitor the scope, nature and cost of available terrorism insurance and maintain terrorism insurance in amounts and on terms that are commercially reasonable. The Company also currently carries earthquake insurance on its properties located in areas known to be subject to earthquakes in an amount and subject to self-insurance that the Company believes are commercially reasonable. In addition, this insurance is subject to a deductible in the amount of 5% of the value of the affected property. Specifically, the Company currently carries earthquake insurance which covers its San Francisco region (excluding 535 Mission Street and the below grade improvements for Transbay Tower) with a $120 million per occurrence limit and a $120 million annual aggregate limit, $20 million of which is provided by IXP, as a direct insurer. The builders risk policy maintained for the development of 535 Mission Street in San Francisco includes a $15 million per occurrence and annual aggregate limit of earthquake coverage. In addition, the builders risk policy maintained for the development of the below grade improvements of the Transbay Tower in San Francisco includes a $15 million per occurrence and annual aggregate limit of earthquake coverage. The amount of the Company’s earthquake insurance coverage may not be sufficient to cover losses from earthquakes. In addition, the amount of earthquake coverage could impact the Company’s ability to finance properties subject to earthquake risk. The Company may discontinue earthquake insurance or change the structure of its earthquake insurance program on some or all of its properties in the future if the premiums exceed the Company’s estimation of the value of the coverage. IXP, a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company’s earthquake insurance coverage for its Greater San Francisco properties, the additional Terrorism Coverage for 601 Lexington Avenue and the Company’s NBCR Coverage. The additional Terrorism Coverage provided by IXP for 601 Lexington Avenue only applies to losses which exceed the program trigger under TRIA. NYXP, a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company’s Terrorism Coverage for 767 Fifth Avenue. Currently, NYXP only insures losses which exceed the program trigger under TRIA and NYXP reinsures with a third-party insurance company any coinsurance payable under TRIA. Insofar as the Company owns IXP and NYXP, it is responsible for their liquidity and capital resources, and the accounts of IXP and NYXP are part of the Company’s consolidated financial statements. In particular, if a loss occurs which is covered by the Company’s NBCR Coverage but is less than the applicable program trigger under TRIA, IXP would be responsible for the full amount of the loss without any backstop by the Federal Government. IXP and NYXP would also be responsible for any recoupment charges by the Federal Government in the event losses are paid out and their insurance policies are maintained after the payout by the Federal Government. If the Company experiences a loss and IXP or NYXP are required to pay under their insurance policies, the Company would ultimately record the loss to the extent of the required payment. Therefore, insurance coverage provided by IXP and NYXP should not be considered as the equivalent of third-party insurance, but rather as a modified form of self-insurance. In addition, the Company has issued a guarantee to cover liabilities of IXP in the amount of $20.0 million. The mortgages on the Company's properties typically contain requirements concerning the financial ratings of the insurers who provide policies covering the property. The Company provides the lenders on a regular basis with the identity of the insurance companies in the Company's insurance programs. The ratings of some of the Company's insurers are below the rating requirements in some of the Company's loan agreements and the lenders for these loans could attempt to claim that an event of default has occurred under the loan. The Company believes it could obtain insurance with insurers which satisfy the rating requirements. Additionally, in the future, the Company's ability to obtain debt financing secured by individual properties, or the terms of such financing, may be adversely affected if lenders generally insist on ratings for insurers or amounts of insurance which are difficult to obtain or which result in a commercially unreasonable premium. There can be no assurance that a deficiency in the financial ratings of one or more of the Company's insurers will not have a material adverse effect on the Company. The Company continues to monitor the state of the insurance market in general, and the scope and costs of coverage for acts of terrorism and California earthquake risk in particular, but the Company cannot anticipate what coverage will be available on commercially reasonable terms in future policy years. There are other types of losses, such as from wars, for which the Company cannot obtain insurance at all or at a reasonable cost. With respect to such losses and losses from acts of terrorism, earthquakes or other catastrophic events, if the Company experiences a loss that is uninsured or that exceeds policy limits, the Company could lose the capital invested in the damaged properties, as well as the anticipated future revenues from those properties. Depending on the specific circumstances of each affected property, it is possible that the Company could be liable for mortgage indebtedness or other obligations related to the property. Any such loss could materially and adversely affect the Company's business and financial condition and results of operations. Legal Matters The Company is subject to various legal proceedings and claims that arise in the ordinary course of business. These matters are generally covered by insurance. Management believes that the final outcome of such matters will not have a material adverse effect on the financial position, results of operations or liquidity of the Company. State and Local Tax Matters Because the Company is a limited partnership, it is generally not subject to federal income taxes, but is subject to certain state and local taxes. In the normal course of business, certain entities through which the Company owns real estate either have undergone, or are currently undergoing, tax audits. Although the Company believes that it has substantial arguments in favor of its positions in the ongoing audits, in some instances there is no controlling precedent or interpretive guidance on the specific point at issue. Collectively, tax deficiency notices received to date from the jurisdictions conducting the ongoing audits have not been material. However, there can be no assurance that future audits will not occur with increased frequency or that the ultimate result of such audits will not have a material adverse effect on the Company’s results of operations. Environmental Matters It is the Company’s policy to retain independent environmental consultants to conduct or update Phase I environmental assessments (which generally do not involve invasive techniques such as soil or ground water sampling) and asbestos surveys in connection with the Company’s acquisition of properties. These pre-purchase environmental assessments have not revealed environmental conditions that the Company believes will have a material adverse effect on its business, assets, financial condition, results of operations or liquidity, and the Company is not otherwise aware of environmental conditions with respect to its properties that the Company believes would have such a material adverse effect. However, from time to time environmental conditions at the Company’s properties have required and may in the future require environmental testing and/or regulatory filings, as well as remedial action. In February 1999, the Company (through a joint venture) acquired from Exxon Corporation a property in Massachusetts that was formerly used as a petroleum bulk storage and distribution facility and was known by the state regulatory authority to contain soil and groundwater contamination. The Company developed an office park on the property. The Company engaged a specially licensed environmental consultant to oversee the management of contaminated soil and groundwater that was disturbed in the course of construction. Under the property acquisition agreement, Exxon agreed to (1) bear the liability arising from releases or discharges of oil and hazardous substances which occurred at the site prior to the Company’s ownership, (2) continue monitoring and/or remediating such releases and discharges as necessary and appropriate to comply with applicable requirements, and (3) indemnify the Company for certain losses arising from preexisting site conditions. Any indemnity claim may be subject to various defenses, and there can be no assurance that the amounts paid under the indemnity, if any, would be sufficient to cover the liabilities arising from any such releases and discharges. Environmental investigations at some of the Company’s properties and certain properties owned by affiliates of the Company have identified groundwater contamination migrating from off-site source properties. In each case the Company engaged a licensed environmental consultant to perform the necessary investigations and assessments and to prepare any required submittals to the regulatory authorities. In each case the environmental consultant concluded that the properties qualify under the regulatory program or the regulatory practice for a status which eliminates certain deadlines for conducting response actions at a site. The Company also believes that these properties qualify for liability relief under certain statutory provisions or regulatory practices regarding upgradient releases. Although the Company believes that the current or former owners of the upgradient source properties may bear responsibility for some or all of the costs of addressing the identified groundwater contamination, the Company will take such further response actions (if any) that it deems necessary or advisable. Other than periodic testing at some of these properties, no such additional response actions are anticipated at this time. Some of the Company’s properties and certain properties owned by the Company’s affiliates are located in urban, industrial and other previously developed areas where fill or current or historical uses of the areas have caused site contamination. Accordingly, it is sometimes necessary to institute special soil and/or groundwater handling procedures and/or include particular building design features in connection with development, construction and other property operations in order to achieve regulatory closure and/or ensure that contaminated materials are addressed in an appropriate manner. In these situations it is the Company’s practice to investigate the nature and extent of detected contamination and estimate the costs of required response actions and special handling procedures. The Company then uses this information as part of its decision-making process with respect to the acquisition and/or development of the property. For example, the Company owns a parcel in Massachusetts which was formerly used as a quarry/asphalt batching facility. Pre-purchase testing indicated that the site contained relatively low levels of certain contaminants. The Company has developed an office park on this property. Prior to and during redevelopment activities, the Company engaged a specially licensed environmental consultant to monitor environmental conditions at the site and prepare necessary regulatory submittals based on the results of an environmental risk characterization. A submittal has been made to the regulatory authorities in order to achieve regulatory closure at this site. The submittal included an environmental deed restriction that mandates compliance with certain protective measures in a portion of the site where low levels of residual soil contamination have been left in place in accordance with applicable laws. The Company expects that resolution of the environmental matters relating to the above will not have a material impact on its business, assets, financial condition, results of operations or liquidity. However, the Company cannot assure you that it has identified all environmental liabilities at its properties, that all necessary remediation actions have been or will be undertaken at the Company’s properties or that the Company will be indemnified, in full or at all, in the event that such environmental liabilities arise. Tax Protection Obligations In connection with the acquisition or contribution of three properties, the Company entered into agreements for the benefit of the selling or contributing parties which specifically state that until such time as the contributors do not hold at least a specified percentage of the OP Units owned by such person following the contribution of the properties, or until June 9, 2017 for 767 Fifth Avenue (the General Motors Building), the Company will not sell or otherwise transfer the properties in a taxable transaction. If the Company does sell or transfer the properties in a taxable transaction, it would be liable to the contributors for contractual damages.

Noncontrolling Interests

12 Months Ended

Dec. 31, 2013

Noncontrolling Interest [Abstract]

Noncontrolling Interests

Noncontrolling interests relate to the interests in the Company not owned by Boston Properties, Inc. and interests in consolidated property partnerships not wholly-owned by the Company. As of December 31, 2013, the noncontrolling interests consisted of 15,583,370 OP Units, 1,455,761 LTIP Units, 396,500 2011 OPP Units, 396,150 2012 OPP Units, 316,325 2013 MYLTIP Units, 666,116 Series Two Preferred Units (or 874,168 OP Units on an as converted basis) and 360,126 Series Four Preferred Units (not convertible into OP Units) held by parties other than Boston Properties, Inc.

Noncontrolling Interest—Redeemable Interest in Property Partnership

On October 4, 2012, the Company completed the formation of a joint venture, which owns and operates Fountain Square located in Reston, Virginia. The joint venture partner contributed the property valued at approximately $385.0 million and related mortgage indebtedness totaling approximately $211.3 million for a nominal 50% interest in the joint venture. The Company contributed cash totaling approximately $87.0 million for its nominal 50% interest, which cash was distributed to the joint venture partner. Pursuant to the joint venture agreement (i) the Company has rights to acquire the partner's nominal 50% interest and (ii) the partner has the right to cause the Company to acquire the partner's interest on January 4, 2016, in each case at a fixed price totaling approximately $102.0 million in cash. The fixed price option rights expire on January 31, 2016. The Company is consolidating this joint venture due to the Company's right to acquire the partner's nominal 50% interest. The Company initially recorded the noncontrolling interest at its acquisition-date fair value as temporary equity, due to the redemption option existing outside the control of the Company. The Company will accrete the changes in the redemption value quarterly over the period from the acquisition date to the earliest redemption date using the effective interest method. The Company will record the accretion after the allocation of net income and distributions of cash flow to the noncontrolling interest account balance.

The following table reflects the activity of the noncontrolling interest—redeemable interest in property partnership in the Company's Fountain Square consolidated joint venture for the for the years ended December 31, 2013 and 2012 (in thousands):



Balance at December 31, 2011	$	—
Acquisition-date fair value of redeemable interest	98,787
Net loss	(719		)
Distributions	(3,032		)
Adjustment to reflect redeemable interest at redemption value	2,522
Balance at December 31, 2012	97,558
Net loss	(1,839		)
Distributions	(4,585		)
Adjustment to reflect redeemable interest at redemption value	8,475
Balance at December 31, 2013	$	99,609

Noncontrolling Interest—Redeemable Preferred Units

The Preferred Units at December 31, 2013 consisted of 666,116 Series Two Preferred Units, which bear a preferred distribution equal to the greater of (1) the distribution which would have been paid in respect of the Series Two Preferred Unit had such Series Two Preferred Unit been converted into an OP Unit (including both regular and special distributions) or (2) 6.00% per annum on a liquidation preference of $50.00 per unit, and are convertible into OP Units at a rate of $38.10 per Preferred Unit (1.312336 OP Units for each Preferred Unit). The holders of Series Two Preferred Units have the right to require the Company to redeem their units for cash at the redemption price of $50.00 per unit on May 12, 2014. The holders also had the right to have their Series Two Preferred Units redeemed for cash on May 12, 2009, May 12, 2010, May 12, 2011, May 14, 2012 and May 14, 2013, although no holder exercised such right. Due to the holders' redemption option existing outside the control of the Company, the Series Two Preferred Units are not included in Partners' Capital in the Company's Consolidated Balance Sheets. In May 2014, the Company's general partner also has the right, subject to certain conditions, to call for redemption all of the outstanding Series Two Preferred Units for cash or to convert into OP Units any Series Two Preferred Units that have not been previously redeemed. In the event the Company's general partner calls the Series Two Preferred Units for redemption, the holders shall have the right to convert the Series Two Preferred Units into OP Units.

During the years ended December 31, 2013 and 2012, 329,881 and 117,047 Series Two Preferred Units of the Company, respectively, were converted by the holders into 432,914 and 153,605 OP Units, respectively. In addition, the Company paid the accrued preferred distributions due to the holders of Preferred Units that were converted.

On February 15, 2013, the Company paid a distribution on its outstanding Series Two Preferred Units of $0.85302 per unit. On May 15, 2013, the Company paid a distribution on its outstanding Series Two Preferred Units of $0.85302 per unit. On August 15, 2013, the Company paid a distribution on its outstanding Series Two Preferred Units of $0.85302 per unit. On November 15, 2013, the Company paid a distribution on its outstanding Series Two Preferred Units of $0.85302 per unit.

Due to the redemption option and the conversion option existing outside the control of the Company, the Series Two Preferred Units are not included in Partners’ Capital and are reflected in the Consolidated Balance Sheets at an amount equivalent to the value of such units had such units been redeemed at December 31, 2013. The value of the Series Two Preferred Units, assuming all of such units had been converted and then redeemed at December 31, 2013, was approximately $87.7 million based on the closing price of Boston Properties, Inc.’s common stock of $100.37 per share on that date.

The Preferred Units at December 31, 2013 also included 360,126 Series Four Preferred Units, which bear a preferred distribution equal to 2.00% per annum on a liquidation preference of $50.00 per unit and are not convertible into OP Units. In order to secure the performance of certain obligations by the holders, such Series Four Preferred Units are subject to forfeiture pursuant to the terms of a pledge agreement. The holders of Series Four Preferred Units have the right, at certain times and subject to certain conditions set forth in the Certificate of Designations establishing the rights, limitations and preferences of the Series Four Preferred Units, to require the Company to redeem all of their units for cash at the redemption price of $50.00 per unit. The Company also has the right, at certain times and subject to certain conditions, to redeem all of the Series Four Preferred Units for cash at the redemption price of $50.00 per unit. The Series Four Preferred Units that are subject to the security interest under the pledge agreement may not be redeemed until and unless such security interest is released. The Company's first right to redeem the Series Four Preferred Units was a 30-day period beginning on August 29, 2013. Due to the holders' redemption option existing outside the control of the Company, the Series Four Preferred Units are not included in Partners' Capital in the Company's Consolidated Balance Sheets. On August 29, 2013, Boston Properties, Inc., in its capacity as the general partner of the Company, redeemed approximately 861,400 Series Four Preferred Units for cash at the redemption price of $50.00 per unit plus accrued and unpaid distributions through the redemption date.

On February 15, 2013, the Company paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit. On May 15, 2013, the Company paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit. On August 15, 2013, the Company paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit. On November 15, 2013, the Company paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit.

The following table reflects the activity of the noncontrolling interests—redeemable preferred units for the years ended December 31, 2013, 2012 and 2011 (in thousands):



Balance at December 31, 2010	$	125,765
Net income	3,339
Distributions	(3,339		)
Reallocation of partnership interest	19,719
Balance at December 31, 2011	145,484
Issuance of redeemable preferred units (Series Four Preferred Units)	79,405
Net income	3,497
Distributions	(3,497		)
Redemption of redeemable preferred units (Series Four Preferred Units)	(18,329		)
Reallocation of partnership interest (1)	(7,182		)
Balance at December 31, 2012	199,378
Net income	6,046
Distributions	(6,046		)
Redemption of redeemable preferred units (Series Four Preferred Units)	(43,070		)
Reallocation of partnership interest (1)	(50,562		)
Balance at December 31, 2013	$	105,746


(1)	Includes the conversion of 329,881 and 117,047 Series Two Preferred Units into 432,914 and 153,605 OP Units during the years ended December 31, 2013 and 2012, respectively.

Noncontrolling Interest—Common Units

During the years ended December 31, 2013 and 2012, 929,441 and 1,110,660 OP Units, respectively, were presented by the holders for redemption (including 432,914 and 153,605 OP Units, respectively, issued upon conversion of Series Two Preferred Units and 24,028 and 544,729 OP Units, respectively, issued upon conversion of LTIP Units) and were redeemed by Boston Properties, Inc. in exchange for an equal number of shares of Common Stock.

At December 31, 2013, the Company had outstanding 396,500 2011 OPP Units and 396,150 2012 OPP Units and 316,325 2013 MYLTIP Units (See Note 17). Prior to the measurement date (January 31, 2014 for 2011 OPP Units (See Note 20), February 6, 2015 for 2012 OPP Units and February 4, 2016 for 2013 MYLTIP Units), holders of OPP Units and 2013 MYLTIP Units are entitled to receive per unit distributions equal to one-tenth (10%) of the regular quarterly distributions payable on an OP Unit, but will not be entitled to receive any special distributions. After the measurement date, the number of OPP Units and 2013 MYLTIP Units, both vested and unvested, that OPP and 2013 MYLTIP award recipients have earned, if any, based on the establishment of an outperformance pool, will be entitled to receive distributions in an amount per unit equal to distributions, both regular and special, payable on an OP Unit.

On January 29, 2013, the Company paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a distribution on the 2011 OPP Units and 2012 OPP Units in the amount of $0.065 per unit, to holders of record as of the close of business on December 31, 2012. On April 30, 2013, the Company paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on March 29, 2013. On July 31, 2013, the Company paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on June 28, 2013. On October 31, 2013, the Company paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit and a distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on September 30, 2013. On November 27, 2013, Boston Properties, Inc., as general partner of the Company, declared a special cash distribution on the OP Units and LTIP Units in the amount of $2.25 per unit payable on January 29, 2014 to holders of record as of the close of business on December 31, 2013. The special cash distribution was in addition to the regular quarterly distribution on the OP Units and LTIP Units of $0.65 per unit and the distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, in each case payable on January 29, 2014 to holders of record as of the close of business on December 31, 2013. Holders of the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units are not entitled to receive any special distributions. Holders of Series Two Preferred Units will participate in the special cash dividend (separately from their regular February 2014 distribution) on an as-converted basis in connection with their regular May 2014 distribution payment as provided in the Company's partnership agreement.

The following table reflects the activity of the noncontrolling interests—redeemable common units for the years ended December 31, 2013, 2012 and 2011 (in thousands):



Balance at December 31, 2010	$	1,801,592
Contributions	23,379
Net income	36,250
Distributions	(39,132		)
Conversion of redeemable partnership units	(85,498		)
Unearned compensation	(1,952		)
Accumulated other comprehensive loss	297
Adjustment to reflect redeemable partnership units at redemption value	74,183
Balance at December 31, 2011	1,809,119
Contributions	24,588
Net income	35,200
Distributions	(41,434		)
Conversion of redeemable partnership units	(34,621		)
Unearned compensation	(883		)
Accumulated other comprehensive loss	273
Adjustment to reflect redeemable partnership units at redemption value	44,280
Balance at December 31, 2012	1,836,522
Contributions	26,398
Net income	84,236
Distributions	(83,448		)
Conversion of redeemable partnership units	(30,291		)
Unearned compensation	1,472
Accumulated other comprehensive loss	252
Adjustment to reflect redeemable partnership units at redemption value	(124,923		)
Balance at December 31, 2013	$	1,710,218

Pursuant to the Company’s Partnership Agreement, certain limited partners in the Company have the right to redeem all or any portion of their interest for cash from the Company. However, Boston Properties, Inc. may elect to acquire the limited partner’s interest by issuing its Common Stock in exchange for the interest. The amount of cash to be paid to the limited partner if the redemption right is exercised and Boston Properties, Inc. does not elect to issue its Common Stock is based on the trading price of Boston Properties, Inc.’s common stock at that time. Due to the redemption option existing outside the control of the Company, such limited partners’ units are not included in Partners’ Capital. The value of the OP Units not owned by Boston Properties, Inc. (including LTIP Units assuming that all conditions had been met for the conversion thereof), assuming all of such units had been redeemed at December 31, 2013 was approximately $1.7 billion based on the closing price of Boston Properties, Inc.’s common stock of $100.37 per share on December 31, 2013.

Noncontrolling Interest—Property Partnerships

The noncontrolling interests in property partnerships consist of the outside equity interests in ventures that are consolidated with the financial results of the Company because the Company exercises control over the entities that own the properties. The equity interests in these ventures that are not owned by the Company, totaling approximately $726.1 million at December 31, 2013 and approximately $(2.0) million at December 31, 2012, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.

On February 7, 2013, the partner in the Company's Transbay Tower joint venture issued a notice that it was electing under the joint venture agreement to reduce its nominal ownership interest in the venture from 50% to 5%. On February 26, 2013, the Company issued a notice to the partner electing to proceed with the venture on that basis. As a result, the Company has a 95% nominal interest in and is consolidating the joint venture. Under the joint venture agreement, if certain return thresholds are achieved the partner will be entitled to an additional promoted interest. Also, under the agreement, (1) the partner has the right to cause the Company to purchase the partner's interest after the defined stabilization date and (2) the Company has the right to acquire the partner's interest on the third anniversary of the stabilization date, in each case at an agreed upon purchase price or appraised value. On March 26, 2013, the consolidated joint venture completed the acquisition of a land parcel in San Francisco, California which will support a 60-story, 1.4 million square foot office tower known as Transbay Tower. The purchase price for the land was approximately $192.0 million. The joint venture has commenced construction of the initial phase of the development consisting of building the project to grade (See Note 3).

On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue(the General Motors Building) in New York City) transferred all of their interests in the joint venture to third parties. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that the Company now accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting. Upon consolidation, the Company recognized the new joint venture partners' aggregate 40% equity interest at its aggregate fair value of approximately $480.9 million within Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets (See Notes 3 and 5).

On October 9, 2013, the Company completed the sale of a 45% ownership interest in its Times Square Tower property for a gross sale price of $684.0 million in cash. Net cash proceeds totaled approximately $673.1 million, after the payment of transaction costs. In connection with the sale, the Company formed a joint venture with the buyer and will provide customary property management and leasing services to the joint venture. Times Square Tower is an approximately 1,246,000 net rentable square foot Class A office tower located in New York City. The transaction did not qualify as a sale of real estate for financial reporting purposes because the Company continues to control the joint venture and will therefore continue to account for the entity on a consolidated basis in its financial statements. The Company has accounted for the transaction as an equity transaction and has recognized noncontrolling interest in its consolidated balance sheets totaling approximately $243.5 million, which is equal to 45% of the carrying value of the total equity of the property immediately prior to the transaction. The difference between the net cash proceeds received and the noncontrolling interest recognized, which difference totals approximately $429.6 million, has not been reflected as a gain on sale of real estate in the Company’s consolidated statements of operations and has instead been reflected as an increase to Partners' Capital in the Company’s consolidated balance sheets (See Notes 3).

The following table reflects the activity of the noncontrolling interests—property partnerships for the years ended December 31, 2013, 2012 and 2011 (in thousands):



Balance at December 31, 2010	$	(614	)
Net income	1,558
Distributions	(2,007		)
Balance at December 31, 2011	(1,063		)
Net income	1,989
Distributions	(2,890		)
Balance at December 31, 2012	(1,964		)
Fair value of capital recorded upon consolidation	480,861
Capital contributions	257,564
Net loss	(5,290		)
Distributions	(5,039		)
Balance at December 31, 2013	$	726,132

Partners' Capital

12 Months Ended

Dec. 31, 2013

Partners' Capital [Abstract]

Partners' Capital

Partners’ Capital

The following table presents the changes in the issued and outstanding partners’ capital units since January 1, 2011:



	General Partner Units	Limited Partner Units	Total Partners’ Capital Units
Outstanding at December 31, 2010	1,610,941	138,588,164	140,199,105
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	42	6,314	6,356
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	2,112	320,499	322,611
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	19,112	2,900,211	2,919,323
Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs	30,508	4,629,708	4,660,216
Outstanding at December 31, 2011	1,662,715	146,444,896	148,107,611
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	57	7,349	7,406
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	216	27,816	28,032
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	8,541	1,102,119	1,110,660
Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs	18,051	2,329,449	2,347,500
Outstanding at December 31, 2012	1,689,580	149,911,629	151,601,209
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	50	6,392	6,442
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	207	26,686	26,893
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	7,158	922,283	929,441
Units issued to Boston Properties, Inc. related to Common Stock issued in connection with the exchange of Exchangeable Senior Notes	3,227	415,889	419,116
Outstanding at December 31, 2013	1,700,222	151,282,879	152,983,101

As of December 31, 2013, Boston Properties, Inc. owned 1,700,222 general partnership units and 151,282,879 limited partnership units.

On January 29, 2013, the Company paid a distribution in the amount of $0.65 per OP Unit to unitholders of record as of the close of business on December 31, 2012. On April 30, 2013, the Company paid a distribution in the amount of $0.65 per OP Unit to unitholders of record as of the close of business on March 29, 2013. On July 31, 2013, the Company paid a distribution in the amount of $0.65 per OP Unit to unitholders of record as of the close of business on June 28, 2013. On October 31, 2013, the Company paid a distribution in the amount of $0.65 per OP Unit to unitholders of record as of the close of business on September 30, 2013.

On November 27, 2013, Boston Properties, Inc.'s Board of Directors declared a special cash distribution of $2.25 per OP Unit payable on January 29, 2014 to unitholders of record as of the close of business on December 31, 2013. The special cash distribution was in addition to the regular quarterly distribution of $0.65 per OP Unit declared by Boston Properties, Inc.'s Board of Directors and payable on January 29, 2014 to unitholders of record as of the close of business on December 31, 2013.

On March 27, 2013, Boston Properties, Inc. completed an underwritten public offering of 80,000 shares (8,000,000 depositary shares each representing 1/100th of a share) of its newly designated 5.25% Series B Cumulative Redeemable Preferred Stock, at a price of $2,500.00 per share ($25.00 per depositary share). The net proceeds from this offering were approximately $193.6 million, after deducting the underwriting discount and transaction expenses. Boston Properties, Inc. contributed the net proceeds to the Company in exchange for 80,000 Series B Preferred Units having terms and preferences generally mirroring those of the Series B Preferred Stock. Boston Properties, Inc. will pay cumulative cash dividends on the Series B Preferred Stock at a rate of 5.25% per annum of the $2,500.00 liquidation preference per share. Boston Properties, Inc. may not redeem the Series B Preferred Stock prior to March 27, 2018, except in certain circumstances relating to the preservation of Boston Properties, Inc.'s REIT status. On or after March 27, 2018, Boston Properties, Inc., at its option, may redeem the Series B Preferred Stock for a cash redemption price of $2,500.00 per share ($25.00 per depositary share), plus all accrued and unpaid dividends. The Series B Preferred Stock is not redeemable by the holders, has no maturity date and is not convertible into any other security of Boston Properties, Inc., the Company or its affiliates.

On May 15, 2013, the Company paid a distribution on its outstanding Series B Preferred Units of $32.8125 per unit. On August 15, 2013, the Company paid a distribution on its outstanding Series B Preferred Units of $32.8125 per unit. On November 15, 2013, the Company paid a distribution on its outstanding Series B Preferred Units of $32.8125 per unit. On November 27, 2013, Boston Properties, Inc.'s Board of Directors declared a distribution of $32.8125 per unit of Series B Preferred Units payable on February 18, 2014 to shareholders of record as of the close of business on February 7, 2014.

The following table reflects the activity of the Series B Preferred Units for the for the year ended December 31, 2013 (in thousands), which activity is included within the Company's Consolidated Statements of Partners' Capital:



Balance at December 31, 2012	$	—
Issuance of Series B Preferred Units	193,623
Net income	8,057
Distributions	(8,057		)
Balance at December 31, 2013	$	193,623

During the year ended December 31, 2013, Boston Properties, Inc. issued 419,116 shares of Common Stock in connection with the exchange by holders of the Company's 3.75% Exchangeable Senior Notes due 2036 (See Note 8). The Company issued 419,116 OP Units to Boston Properties, Inc.

As of December 31, 2013, approximately $305.3 million remained available for issuance under Boston Properties, Inc.'s $600 million “at the market” stock offering program. No shares were issued under the “at the market” stock offering program during the year ended December 31, 2013.

During the year ended December 31, 2013, the Company did not issue any OP Units to Boston Properties, Inc. in connection with the exercise by employees of options to purchase Common Stock of Boston Properties, Inc. During the year ended December 31, 2012, the Company issued 22,823 OP Units to Boston Properties, Inc. in connection with the exercise by certain employees of options to purchase Common Stock of Boston Properties, Inc.

During the year ended December 31, 2013 and 2012, Boston Properties, Inc. acquired 929,441 and 1,110,660 OP Units, respectively, in connection with the redemption of an equal number of redeemable OP Units from third parties.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Section S99
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
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Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
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Reference 16: http://www.xbrl.org/2003/role/presentationRef
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Reference 17: http://www.xbrl.org/2003/role/presentationRef
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Reference 18: http://www.xbrl.org/2003/role/presentationRef
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Reference 19: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Future Minimum Rents

12 Months Ended

Dec. 31, 2013

Future Minimum Rents [Abstract]

Future Minimum Rents [Text Block]

13. Future Minimum Rents

The properties are leased to tenants under net operating leases with initial term expiration dates ranging from 2014 to 2048. The future contractual minimum lease payments to be received (excluding operating expense reimbursements) by the Company as of December 31, 2013, under non-cancelable operating leases which expire on various dates through 2048, are as follows:



Years Ending December 31,	(in thousands)
2014	$	1,716,754
2015	1,706,282
2016	1,660,890
2017	1,510,645
2018	1,342,157
Thereafter	6,674,466

No single tenant represented more than 10.0% of the Company’s total rental revenue for the years ended December 31, 2013, 2012 and 2011.

Segment Information

12 Months Ended

Dec. 31, 2013

Segment Reporting [Abstract]

Segment Information

The Company’s segments are based on the Company’s method of internal reporting, which classifies its operations by both geographic area and property type. Beginning on January 1, 2014, the properties that were historically part of the Princeton region have been reflected as the suburban component of the New York region. The operations for the Princeton region, including the reclassification between Rental Operating Expenses and General and Administrative Expenses for the years ended December 31, 2013, 2012 and 2011 as detailed below, have been included in the New York region. Accordingly, amounts reflected below for the New York region have been adjusted to reflect the Company's retrospective inclusion of the Princeton region in the New York region. The Company’s segments by geographic area are Boston, New York, San Francisco and Washington, DC. Segments by property type include: Class A Office, Office/Technical, Residential and Hotel.

Asset information by segment is not reported because the Company does not use this measure to assess performance. Therefore, depreciation and amortization expense is not allocated among segments. Interest and other income, development and management services, general and administrative expenses, transaction costs, interest expense, depreciation and amortization expense, gains (losses) from investments in securities, gains (losses) from early extinguishments of debt, income from unconsolidated joint ventures, gains on consolidation of joint ventures, impairment loss, discontinued operations and noncontrolling interests are not included in Net Operating Income as internal reporting addresses these items on a corporate level.

Net Operating Income is not a measure of operating results or cash flows from operating activities as measured by accounting principles generally accepted in the United States of America, and it is not indicative of cash available to fund cash needs and should not be considered an alternative to cash flows as a measure of liquidity. All companies may not calculate Net Operating Income in the same manner. The Company considers Net Operating Income to be an appropriate supplemental measure to net income because it helps both investors and management to understand the core operations of the Company’s properties.

We have modified the presentation of expenses to operate our San Francisco and Princeton regional offices to reflect the growing activity in our San Francisco region and to have a consistent presentation across our company. For San Francisco these expenses, which totaled approximately $6.7 million, $6.1 million and $6.0 million for the years ended December 31, 2013, 2012 and 2011, respectively, and for Princeton these expenses were approximately $1.4 million, $1.6 million and $1.5 million for the years ended December 31, 2013, 2012 and 2011, respectively, were previously included in Rental Operating Expenses and are now included in General and Administrative Expenses for all periods presented.

On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties (See Note 3). Effective as of May 31, 2013, the Company accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting. Upon consolidation, the operations for this building are included in the New York region.

Information by geographic area and property type (dollars in thousands):

For the year ended December 31, 2013:



	Boston			New York			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	665,991		$	725,566		$	214,755		$	381,359		$	1,987,671
Office/Technical	22,617			—			17,259			15,649			55,525
Residential	4,395			—			—			17,923			22,318
Hotel	40,330			—			—			—			40,330
Total	733,333			725,566			232,014			414,931			2,105,844
% of Grand Totals	34.82		%	34.46		%	11.02		%	19.70		%	100.00		%
Rental Expenses:
Class A Office	259,997			251,640			77,905			126,507			716,049
Office/Technical	6,879			—			3,708			4,190			14,777
Residential	1,823			—			—			10,307			12,130
Hotel	28,447			—			—			—			28,447
Total	297,146			251,640			81,613			141,004			771,403
% of Grand Totals	38.52		%	32.62		%	10.58		%	18.28		%	100.00		%
Net operating income	$	436,187		$	473,926		$	150,401		$	273,927		$	1,334,441
% of Grand Totals	32.69		%	35.51		%	11.27		%	20.53		%	100.00		%

For the year ended December 31, 2012:



	Boston			New York			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	617,652		$	543,194		$	208,177		$	346,402		$	1,715,425
Office/Technical	22,460			—			494			16,264			39,218
Residential	3,936			—			—			16,632			20,568
Hotel	37,915			—			—			—			37,915
Total	681,963			543,194			208,671			379,298			1,813,126
% of Grand Totals	37.61		%	29.96		%	11.51		%	20.92		%	100.00		%
Rental Expenses:
Class A Office	242,904			187,987			75,542			111,049			617,482
Office/Technical	6,499			—			149			3,966			10,614
Residential	1,675			—			—			9,317			10,992
Hotel	28,120			—			—			—			28,120
Total	279,198			187,987			75,691			124,332			667,208
% of Grand Totals	41.85		%	28.18		%	11.34		%	18.63		%	100.00		%
Net operating income	$	402,765		$	355,207		$	132,980		$	254,966		$	1,145,918
% of Grand Totals	35.15		%	31.00		%	11.60		%	22.25		%	100.00		%

For the year ended December 31, 2011:



	Boston			New York			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	537,743		$	521,439		$	207,003		$	340,470		$	1,606,655
Office/Technical	25,349			—			—			16,236			41,585
Residential	985			—			—			5,632			6,617
Hotel	34,529			—			—			—			34,529
Total	598,606			521,439			207,003			362,338			1,689,386
% of Grand Totals	35.43		%	30.87		%	12.25		%	21.45		%	100.00		%
Rental Expenses:
Class A Office	206,469			181,269			72,122			95,804			555,664
Office/Technical	7,245			—			—			4,280			11,525
Residential	521			—			—			4,958			5,479
Hotel	26,128			—			—			—			26,128
Total	240,363			181,269			72,122			105,042			598,796
% of Grand Totals	40.14		%	30.27		%	12.05		%	17.54		%	100.00		%
Net operating income	$	358,243		$	340,170		$	134,881		$	257,296		$	1,090,590
% of Grand Totals	32.85		%	31.19		%	12.37		%	23.59		%	100.00		%

The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership:



	Year ended December 31,
		2013		2012			2011
Net Operating Income		$	1,334,441	$	1,145,918		$	1,090,590
Add:
Development and management services income		29,695		34,060			33,406
Income from unconsolidated joint ventures		75,074		49,078			85,896
Gains on consolidation of joint ventures		385,991		—			—
Interest and other income		8,310		10,091			5,358
Gains (losses) from investments in securities		2,911		1,389			(443		)
Gains (losses) from early extinguishments of debt		122		(4,453		)	(1,494		)
Income from discontinued operations		8,022		9,806			10,876
Gains on sales of real estate from discontinued operations		115,459		38,445			—
Gain on forgiveness of debt from discontinued operations		20,736		—			—
Less:
General and administrative expense		115,329		90,129			87,101
Transaction costs		1,744		3,653			1,987
Depreciation and amortization expense		552,589		437,692			421,519
Interest expense		446,880		410,970			391,533
Impairment loss		4,401		—			—
Impairment loss from discontinued operations		2,852		—			—
Noncontrolling interest in property partnerships		1,347		3,792			1,558
Noncontrolling interest—redeemable preferred units		14,103		3,497			3,339
Net income attributable to Boston Properties Limited Partnership		$	841,516	$	334,601		$	317,152

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8538-108599

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8906-108599

+ Details

Earnings Per Common Unit

12 Months Ended

Dec. 31, 2013

Earnings Per Share [Abstract]

Earnings Per Common Unit

The following table provides a reconciliation of both the net income attributable to Boston Properties Limited Partnership and the number of common units used in the computation of basic earnings per common unit, which is calculated by dividing net income attributable to Boston Properties Limited Partnership by the weighted-average number of common units outstanding during the period. The terms of the Series Two Preferred Units enable the holders to obtain OP Units of the Company and as a result these are considered participating securities. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of Boston Properties, Inc. and the Company’s LTIP Units, OPP Units and 2013 MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic earnings per common unit using the two-class method. Participating securities are included in the computation of diluted earnings per common unit using the if-converted method if the impact is dilutive. Because the OPP Units and 2013 MYLTIP Units require Boston Properties, Inc. to outperform absolute and relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, the Company excludes such units from the diluted earnings per common unit calculation. Other potentially dilutive common units and the related impact on earnings are considered when calculating diluted earnings per common unit. Included in the number of units (the denominator) below are approximately 16,925,000, 17,649,000 and 18,793,000 redeemable common units for the years ended December 31, 2013, 2012 and 2011, respectively.



	For the Year Ended December 31, 2013
	Income (Numerator)			Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties Limited Partnership	$	700,151		169,126	$	4.14
Discontinued operations attributable to Boston Properties Limited Partnership	141,365			—	0.84
Allocation of undistributed earnings to participating securities	(178		)	—	(0.01		)
Net income attributable to Boston Properties Limited Partnership	$	841,338		169,126	$	4.97
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—			320	—
Diluted Earnings:
Net income	$	841,338		169,446	$	4.97



	For the Year Ended December 31, 2012
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties Limited Partnership	$	286,350	167,769	$	1.70
Discontinued operations attributable to Boston Properties Limited Partnership	48,251		—	0.29
Net income attributable to Boston Properties Limited Partnership	$	334,601	167,769	$	1.99
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—		591	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership	$	334,601	168,360	$	1.99

	For the Year Ended December 31, 2011
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties Limited Partnership	$	306,276	164,486	$	1.86
Discontinued operations attributable to Boston Properties Limited Partnership	10,876		—	0.07
Net income attributable to Boston Properties Limited Partnership	$	317,152	164,486	$	1.93
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—		525	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership	$	317,152	165,011	$	1.92

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2013
Employee Benefit Plans [Abstract]
Compensation and Employee Benefit Plans [Text Block]	16. Employee Benefit Plans Effective January 1, 1985, the predecessor of the Company adopted a 401(k) Savings Plan (the “Plan”) for its employees. Under the Plan, as amended, employees, as defined, are eligible to participate in the Plan after they have completed three months of service. Upon formation, the Company adopted the Plan and the terms of the Plan. Effective January 1, 2000, the Company amended the Plan by increasing the Company’s matching contribution to 200% of the first 3% from 200% of the first 2% of participant’s eligible earnings contributed (utilizing earnings that are not in excess of an amount established by the IRS ($255,000, $250,000 and $245,000 in 2013, 2012 and 2011, respectively), indexed for inflation) and by eliminating the vesting requirement. The Company’s aggregate matching contribution for the years ended December 31, 2013, 2012 and 2011 was $3.4 million, $3.2 million and $3.1 million, respectively. Effective January 1, 2001, the Company amended the Plan to provide a supplemental retirement contribution to certain employees who have at least ten years of service on January 1, 2001, and who are 40 years of age or older as of January 1, 2001. The maximum supplemental retirement contribution will not exceed the annual limit on contributions established by the IRS. The Company will record an annual supplemental retirement credit for the benefit of each participant. The Company’s supplemental retirement contribution and credit for the years ended December 31, 2013, 2012 and 2011 was $60,000, $78,000 and $62,000, respectively. The Company also maintains a deferred compensation plan that is designed to allow officers of the Company to defer a portion of their current income on a pre-tax basis and receive a tax-deferred return on these deferrals. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2013 and 2012, the Company had maintained approximately $16.6 million and $12.2 million, respectively, in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the plan participants and earnings on the deferred compensation pursuant to investments elected by the plan participants. The Company’s liability as of December 31, 2013 and 2012 was $16.6 million and $12.2 million, respectively, which are included in the accompanying Consolidated Balance Sheets.

Stock Option and Incentive Plan

12 Months Ended

Dec. 31, 2013

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Option and Incentive Plan

At Boston Properties, Inc.'s 2012 annual meeting of stockholders held on May 15, 2012, the stockholders of Boston Properties, Inc. approved the Boston Properties, Inc. 2012 Stock Option and Incentive Plan (the “2012 Plan”). The 2012 Plan replaced the 1997 Stock Option and Incentive Plan (the “1997 Plan”). The material terms of the 2012 Plan include, among other things: (1) the maximum number of shares of common stock reserved and available for issuance under the 2012 Plan is the sum of (i) 13,000,000 newly authorized shares, plus (ii) the number of shares available for grant under the 1997 Stock Plan immediately prior to the effective date of the 2012 Plan, plus (iii) any shares underlying grants under the 1997 Plan that are forfeited, cancelled or terminated (other than by exercise) in the future; (2) “full-value” awards (i.e., awards other than stock options) are multiplied by a 2.32 conversion ratio to calculate the number of shares available under the 2012 Plan that are used for each full-value award, as opposed to a 1.0 conversion ratio for each stock option awarded under the 2012 Plan; (3) shares tendered or held back for taxes will not be added back to the reserved pool under the 2012 Plan; (4) stock options may not be re-priced without stockholder approval; and (5) the term of the 2012 Plan is for ten years from the date of stockholder approval.

On January 28, 2013, Boston Properties, Inc.'s Compensation Committee approved multi-year long-term incentive program (MYLTIP) awards under Boston Properties, Inc.'s 2012 Plan to officers and employees of Boston Properties, Inc. MYLTIP awards utilize total return to shareholders ("TRS") over a three-year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on Boston Properties, Inc.'s TRS relative to (i) the Cohen & Steers Realty Majors Portfolio Index (50% weight) and (ii) the NAREIT Office Index adjusted to exclude Boston Properties, Inc. (50% weight). Earned awards will range from zero to a maximum of approximately $30.7 million depending on Boston Properties, Inc.'s TRS relative to the two indices, with four tiers (threshold: approximately $5.1 million; target: approximately $10.2 million; high: approximately $20.5 million; exceptional: approximately $30.7 million) and linear interpolation between tiers. Earned awards measured on the basis of relative TRS performance are subject to an absolute TRS component in the form of relatively simple modifiers that (A) reduce the level of earned awards in the event Boston Properties, Inc.'s annualized TRS is less than 2% and (B) cause some awards to be earned in the event Boston Properties, Inc.'s annualized TRS is more than 10% even though on a relative basis alone Boston Properties, Inc.'s TRS would not result in any earned awards.

Earned awards (if any) will vest 25% on February 4, 2016, 25% on February 4, 2017 and 50% on February 4, 2018, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by Boston Properties, Inc. without cause, termination of employment by the award recipient for good reason, death, disability or retirement. If there is a change of control prior to February 4, 2016, earned awards will be calculated based on TRS performance up to the date of the change of control. MYLTIP awards are in the form of LTIP Units issued on the grant date which (i) are subject to forfeiture to the extent awards are not earned and (ii) prior to the performance measurement date are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units.

On March 11, 2013, Boston Properties, Inc. announced that Owen D. Thomas would succeed Mortimer B. Zuckerman as Boston Properties, Inc.'s Chief Executive Officer, effective April 2, 2013. On April 2, 2013, the Company issued 24,231 LTIP units, 38,926 2013 MYLTIP Units and 50,847 non-qualified stock options under the 2012 Plan to Mr. Thomas, pursuant to his employment agreement. Mr. Zuckerman will continue to serve as Executive Chairman for a transition period and thereafter is expected to continue to serve as the Non-Executive Chairman of the Board of Boston Properties, Inc. In connection with succession planning, Boston Properties, Inc. and Mr. Zuckerman entered into a Transition Benefits Agreement. If Mr. Zuckerman remains employed by Boston Properties, Inc. through July 1, 2014, he will be entitled to receive on January 1, 2015 a lump sum cash payment of $6.7 million and an equity award with a targeted value of approximately $11.1 million. The cash payment and equity award vest one-third on each of March 10, 2013, October 1, 2013 and July 1, 2014, subject to acceleration in certain circumstances. As a result, Boston Properties, Inc. recognized approximately $13.8 million of compensation expense during the year ended December 31, 2013. In addition, the agreement provides that if Mr. Zuckerman terminates his employment with Boston Properties, Inc. for any reason, voluntarily or involuntarily, he will become fully vested in any outstanding equity awards with time-based vesting. As a result, during the year ended December 31, 2013, Boston Properties, Inc. accelerated the remaining approximately $12.9 million of stock-based compensation expense associated with Mr. Zuckerman's unvested long-term equity awards.

Under the Financial Accounting Standards Board's Accounting Standards Codification (“ASC”) 718 “Compensation-Stock Compensation” the MYLTIP awards granted to employees in February 2013 and granted to Mr. Thomas in April 2013 have an aggregate value of approximately $9.2 million, which amount will generally be amortized into earnings over the five-year plan period under the graded vesting method.

Boston Properties, Inc. issued 36,730, 20,756 and 19,030 shares of restricted common stock and 184,733, 174,650 and 190,067 LTIP Units to employees and non-employee directors under the 1997 Plan and 2012 Plan during the years ended December 31, 2013, 2012 and 2011. Boston Properties, Inc. issued 252,220, 186,007 and 146,844 non-qualified stock options under the 1997 Plan during the years ended December 31, 2013, 2012 and 2011. The amounts issued during 2013 include the amounts issued to Mr. Thomas pursuant to his employment agreement, as discussed above. Boston Properties, Inc. issued 400,000 2011 OPP Units to employees under the 1997 Plan during the year ended December 31, 2011. Boston Properties, Inc. issued 400,000 2012 OPP Units to employees under the 1997 Plan during the year ended December 31, 2012. Boston Properties, Inc. issued 318,926 2013 MYLTIP Units to employees under the 2012 Plan during the year ended December 31, 2013, including the amounts issued to Mr. Thomas pursuant to his employment agreement, as discussed above. Employees and directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit, OPP Unit and 2013 MYLTIP Unit. An LTIP Unit is generally the economic equivalent of a share of restricted stock in Boston Properties, Inc. The aggregate value of the LTIP Units is included in noncontrolling interests in the Consolidated Balance Sheets. Grants of restricted stock and LTIP Units to employees vest in four equal annual installments. Restricted stock is measured at fair value on the date of grant based on the number of shares granted, as adjusted for forfeitures, and the closing price of Boston Properties, Inc.’s Common Stock on the date of grant as quoted on the New York Stock Exchange. Such value is recognized as an expense ratably over the corresponding employee service period. Non-qualified stock options, which are valued using the Black-Scholes option-pricing model, are recognized as an expense ratably over the corresponding employee service period. As the 2011 OPP Awards, 2012 OPP Awards and 2013 MYLTIP Awards are subject to both a service condition and a market condition, the Company recognizes the compensation expense related to the 2011 OPP Awards, 2012 OPP Awards and 2013 MYLTIP Awards under the graded vesting attribution method. Under the graded vesting attribution method, each portion of the award that vests at a different date is accounted for as a separate award and recognized over the period appropriate to that portion so that the compensation cost for each portion should be recognized in full by the time that portion vests. Dividends paid on both vested and unvested shares of restricted stock are charged directly to Partners’ Capital in the Consolidated Balance Sheets. Aggregate stock-based compensation expense associated with restricted stock, non-qualified stock options, LTIP Units, 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units was approximately $43.9 million, $28.3 million and $28.3 million for the years ended December 31, 2013, 2012 and 2011, respectively. For the year ended December 31, 2013, stock-based compensation expense includes approximately $21.5 million consisting of the acceleration of the expense of Boston Properties, Inc.’s Executive Chairman’s stock-based compensation awards and the stock-based compensation awards associated with his transition benefits agreement related to Boston Properties, Inc.'s succession planning. For the year ended December 31, 2012, stock-based compensation expense includes approximately $2.7 million consisting of the acceleration of vesting of Boston Properties, Inc.'s Chief Operating Officer’s stock-based compensation awards associated with his resignation. Upon the conclusion of the three-year measurement period in February 2011, the 2008 OPP Awards were not earned, the program was terminated and the Company accelerated the then remaining unrecognized compensation expense totaling approximately $4.3 million during the year ended December 31, 2011. At December 31, 2013, there was $17.6 million of unrecognized compensation expense related to unvested restricted stock and LTIP Units and $11.1 million of unrecognized compensation expense related to unvested 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units that is expected to be recognized over a weighted-average period of approximately 2.7 years (See Note 20).

The shares of restricted stock were valued at approximately $3.9 million ($105.30 per share weighted-average), $2.2 million ($107.31 per share weighted-average) and $1.8 million ($93.40 per share weighted-average) for the years ended December 31, 2013, 2012 and 2011, respectively.

LTIP Units were valued using a Monte Carlo simulation method model in accordance with the provisions of ASC 718 “Compensation—Stock Compensation” (“ASC 718”). LTIP Units issued during the years ended December 31, 2013, 2012 and 2011 were valued at approximately $17.8 million, $17.3 million and $16.5 million, respectively. The weighted-average per unit fair value of LTIP Unit grants in 2013, 2012 and 2011 was $96.13, $98.83 and $86.74, respectively. The per unit fair value of each LTIP Unit granted in 2013, 2012 and 2011 was estimated on the date of grant using the following assumptions; an expected life of 5.7 years, 5.8 years and 5.8 years, a risk-free interest rate of 1.03%, 0.94% and 2.22% and an expected price volatility of 26.0%, 29.1% and 30.0%, respectively.

The non-qualified stock options granted during the years ended December 31, 2013, 2012 and 2011 had a weighted-average fair value on the date of grant of $18.46, $19.50 and $24.67 per option, respectively, which was computed using the Black-Scholes option-pricing model utilizing the following assumptions: an expected life of 6.0 years, 5.4 years and 6.0 years, a risk-free interest rate of 1.11%, 0.92% and 2.37%, an expected price volatility of 26.0%, 28.4% and 35.0% and an expected dividend yield of 3.0%, 2.9% and 3.0%, respectively. The exercise price of the options granted during the years ended December 31, 2013, 2012 and 2011 where $105.10, $107.23 and $92.71, respectively, which was the closing price of Boston Properties, Inc.’s common stock on the date of grant.

A summary of the status of Boston Properties, Inc.’s stock options as of December 31, 2013, 2012 and 2011 and changes during the years then ended are presented below:



	Shares		Weighted Average Exercise Price
Outstanding at December 31, 2010	324,938		$	32.65
Granted	146,844		$	92.71
Exercised	(316,159	)	$	32.63
Canceled	—		$	—
Outstanding at December 31, 2011	155,623		$	89.35
Granted	186,007		$	107.23
Exercised	(22,823	)	$	72.42
Canceled	(24,280	)	$	100.15
Outstanding at December 31, 2012	294,527		$	101.06
Granted	252,220		$	104.50
Exercised	—		$	—
Canceled	—		$	—
Special dividend adjustment	12,076		$	100.44
Outstanding at December 31, 2013	558,823		$	100.43

The following table summarizes information about stock options outstanding at December 31, 2013:



Options Outstanding						Options Exercisable
Exercise Prices		Number Outstanding at 12/31/13	Remaining Contractual Life	Exercise Price		Number Exercisable at 12/31/13	Exercise Price
$	90.71	131,837	7.1 years	$	90.71	80,240	$	90.71
$	99.94	51,971	9.3 years	$	99.94	—	$	—
$	102.83	205,821	9.1 years	$	102.83	48,026	$	102.83
$	105.25	169,194	8.1 years	$	105.25	71,602	$	105.25

The total intrinsic value of the outstanding and exercisable stock options as of December 31, 2013 was approximately $0.8 million. In addition, the Company had 91,496 and 13,633 options exercisable at a weighted-average exercise price of $98.92 and $54.32 at December 31, 2012 and 2011, respectively.

Boston Properties, Inc. adopted the 1999 Non-Qualified Employee Stock Purchase Plan (the “Stock Purchase Plan”) to encourage the ownership of Common Stock by eligible employees. The Stock Purchase Plan became effective on January 1, 1999 with an aggregate maximum of 250,000 shares of Common Stock available for issuance. The Stock Purchase Plan provides for eligible employees to purchase on the business day immediately following the end of the biannual purchase periods (i.e., January 1-June 30 and July 1-December 31) shares of Common Stock at a purchase price equal to 85% of the average closing prices of the Common Stock during the last ten business days of the purchase period. Boston Properties, Inc. issued 6,442, 7,406 and 6,356 shares with the weighted average purchase price equal to $89.65 per share, $86.52 per share and $80.13 per share under the Stock Purchase Plan during the years ended December 31, 2013, 2012 and 2011, respectively.

Related Party Transactions

12 Months Ended

Dec. 31, 2013

18. Related Party Transactions

Prior to joining the Company effective January 2, 2014, Mr. John F. Powers provided commercial real estate brokerage services to the Company, on behalf of his prior employer, CBRE, in connection with certain leasing transactions. Mr. Powers received approximately $592,000 during the year ended December 31, 2013 in connection with these transactions. Mr. John F. Powers is a Senior Vice President of Boston Properties, Inc. and the Regional Manager of its New York office.

A firm controlled by Mr. Raymond A. Ritchey’s brother was paid aggregate leasing commissions of approximately $868,000, $1,306,000 and $671,000 for the years ended December 31, 2013, 2012 and 2011, respectively, related to certain exclusive leasing arrangements for certain Northern Virginia properties. Mr. Ritchey is an Executive Vice President of Boston Properties, Inc.

On June 30, 1998, the Company acquired from entities controlled by Mr. Alan B. Landis, a former director, a portfolio of properties known as the Carnegie Center Portfolio and Tower Center One and related operations and development rights (collectively, the “Carnegie Center Portfolio”). In connection with the acquisition of the Carnegie Center Portfolio, the Company entered into a development agreement (the “Development Agreement”) with affiliates of Mr. Landis providing for up to approximately 2,000,000 square feet of development in or adjacent to the Carnegie Center office complex. An affiliate of Mr. Landis was entitled to a purchase price for each parcel developed under the Development Agreement calculated on the basis of $20 per rentable square foot of property developed. Another affiliate of Mr. Landis was eligible to earn a contingent payment for each developed property that achieves a stabilized return in excess of a target annual return ranging between 10.5% and 11%. The Development Agreement also provided that upon negotiated terms and conditions, the Company and Mr. Landis would form a development company to provide development services for these development projects and would share the expenses and profits, if any, of this new company. In addition, in connection with the acquisition of the Carnegie Center Portfolio, Mr. Landis became a director of Boston Properties, Inc. pursuant to an Agreement Regarding Directorship, dated as of June 30, 1998, with Boston Properties, Inc. (the “Directorship Agreement”). Under the Directorship Agreement, Boston Properties, Inc. agreed to nominate Mr. Landis for re-election as a director at each annual meeting of stockholders of Boston Properties, Inc. in a year in which his term expires, provided that specified conditions are met.

On October 21, 2004, the Company entered into an agreement (the “2004 Agreement”) to modify several provisions of the Development Agreement. Under the terms of the 2004 Agreement, the Company and affiliates of Mr. Landis amended the Development Agreement to limit the rights of Mr. Landis and his affiliates to participate in the development of properties under the Development Agreement. Among other things, Mr. Landis agreed that (1) Mr. Landis and his affiliates will have no right to participate in any entity formed to acquire land parcels or the development company formed by the Company to provide development services under the Development Agreement, (2) Mr. Landis will have no right or obligation to play a role in development activities engaged in by the development company formed by the Company under the Development Agreement or receive compensation from the development company and (3) the affiliate of Mr. Landis will have no right to receive a contingent payment for developed properties based on stabilized returns. In exchange, the Company (together with Boston Properties, Inc.) agreed to:

•

effective as of June 30, 1998, pay Mr. Landis $125,000 on January 1 of each year until the earlier of (A) January 1, 2018, (B) the termination of the Development Agreement or (C) the date on which all development properties under the Development Agreement have been conveyed pursuant to the Development Agreement, with $750,000, representing payments of this annual amount from 1998 to 2004, being paid upon execution of the 2004 Agreement; and

•

pay an affiliate of Mr. Landis, in connection with the development of land parcels acquired under the Development Agreement, an aggregate fixed amount of $10.50 per rentable square foot of property developed (with a portion of this amount (i.e., $5.50) being subject to adjustment, in specified circumstances, based on future increases in the Consumer Price Index) in lieu of a contingent payment based on stabilized returns, which payment could have been greater or less than $10.50 per rentable square foot of property developed.

The Company also continues to be obligated to pay an affiliate of Mr. Landis the purchase price of $20 per rentable square foot of property developed for each land parcel acquired as provided in the original Development Agreement. During the 20-year term of the Development Agreement, until such time, if any, as the Company elects to acquire a land parcel, an affiliate of Mr. Landis will remain responsible for all carrying costs associated with such land parcel. On July 24, 2007, the Company acquired from Mr. Landis 701 Carnegie Center, a land parcel located in Princeton, New Jersey for a purchase price of approximately $3.1 million.

In addition, in connection with entering into the 2004 Agreement, Mr. Landis resigned as a director of Boston Properties, Inc. effective as of May 11, 2005 and agreed that Boston Properties, Inc. had no future obligation to nominate Mr. Landis as a director of Boston Properties, Inc. under the Directorship Agreement or otherwise. Mr. Landis did not resign because of a disagreement with Boston Properties, Inc. on any matter relating to its operations, policies or practices. Mitchell S. Landis, the Senior Vice President and Regional Manager of the Company’s Princeton, New Jersey region, is the brother of Alan B. Landis.

In accordance with Boston Properties, Inc.’s 2012 Plan, and as approved by the Board of Directors of Boston Properties, Inc., six non-employee directors made an election to receive deferred stock units in lieu of cash fees for 2013. The deferred stock units will be settled in shares of common stock upon the cessation of such director’s service on the Board of Directors of Boston Properties, Inc. As a result of these elections, the aggregate cash fees otherwise payable to a non-employee director during a fiscal quarter are converted into a number of deferred stock units equal to the aggregate cash fees divided by the last reported sales price of a share of Boston Properties, Inc.’s common stock on the last trading of the applicable fiscal quarter. The deferred stock units are also credited with dividend equivalents as dividends are paid by Boston Properties, Inc. At December 31, 2013 and 2012, Boston Properties, Inc. had outstanding 83,995 and 76,682 deferred stock units, respectively.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Selected Interim Financial Information (unaudited)

12 Months Ended

Dec. 31, 2013

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information [Text Block]

19. Selected Interim Financial Information (unaudited)

The tables below reflect the Company’s selected quarterly information for the years ended December 31, 2013 and 2012. Total revenue and income from continuing operations amounts have been reclassified for properties qualifying for discontinued operations presentation (See Note 3).



	2013 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per unit amounts)
Total revenue	$	477,826	$	510,033	$	571,481	$	576,199
Income from continuing operations	$	44,445	$	505,396	$	84,348	$	81,412
Net income attributable to Boston Properties Limited Partnership	$	60,923	$	505,189	$	174,140	$	101,264
Income attributable to Boston Properties Limited Partnership per unit—basic	$	0.36	$	2.97	$	1.03	$	0.60
Income attributable to Boston Properties Limited Partnership per unit—diluted	$	0.36	$	2.96	$	1.02	$	0.60



	2012 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per unit amounts)
Total revenue	$	438,722	$	466,197	$	464,220	$	478,047
Income from continuing operations	$	55,133	$	96,836	$	65,375	$	76,295
Net income attributable to Boston Properties Limited Partnership	$	56,542	$	136,561	$	66,234	$	75,264
Income attributable to Boston Properties Limited Partnership per unit—basic	$	0.34	$	0.81	$	0.39	$	0.45
Income attributable to Boston Properties Limited Partnership per unit—diluted	$	0.34	$	0.81	$	0.39	$	0.45

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2013
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 27, 2014, Boston Properties, Inc.'s Compensation Committee approved the 2014 multi-year, long-term incentive program (the "2014 MYLTIP") awards under Boston Properties, Inc.'s 2012 Plan to certain officers and employees of Boston Properties, Inc. The 2014 MYLTIP awards utilize TRS over a three-year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on Boston Properties, Inc.'s TRS relative to (i) the Cohen & Steers Realty Majors Portfolio Index (50% weight) and (ii) the NAREIT Office Index adjusted to exclude Boston Properties, Inc. (50% weight). Earned awards will range from zero to a maximum of approximately $40.2 million depending on the Boston Properties, Inc.'s TRS relative to the two indices, with four tiers (threshold: approximately $6.7 million; target: approximately $13.4 million; high: approximately $26.8 million; exceptional: approximately $40.2 million) and linear interpolation between tiers. Earned awards measured on the basis of relative TRS performance are subject to an absolute TRS component in the form of relatively simple modifiers that (A) reduce the level of earned awards in the event Boston Properties, Inc.'s annualized TRS is less than 0% and (B) cause some awards to be earned in the event Boston Properties, Inc.'s annualized TRS is more than 12% even though on a relative basis alone Boston Properties, Inc.'s TRS would not result in any earned awards. Earned awards (if any) will vest 50% on February 3, 2017 and 50% on February 3, 2018, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by Boston Properties, Inc. without cause, termination of employment by the award recipient for good reason, death, disability or retirement. If there is a change of control prior to February 3, 2017, earned awards will be calculated based on TRS performance up to the date of the change of control. The 2014 MYLTIP awards are in the form of LTIP Units issued on the grant date which (i) are subject to forfeiture to the extent awards are not earned and (ii) prior to the performance measurement date are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units. Under the Financial Accounting Standards Board's Accounting Standards Codification (“ASC”) 718 “Compensation-Stock Compensation” the 2014 MYLTIP awards have an aggregate value of approximately $13.1 million, which amount will generally be amortized into earnings over the four-year plan period under the graded vesting method. On January 31, 2014, Boston Properties, Inc. issued 21,455 shares of restricted common stock and the Company issued 109,718 LTIP units under the 2012 Plan to certain employees of Boston Properties, Inc. On January 31, 2014, the measurement period for the Company’s 2011 OPP Awards expired and Boston Properties, Inc.’s TRS performance was not sufficient for employees to earn and therefore become eligible to vest in any of the 2011 OPP Awards. As a result, the Company accelerated the then remaining unrecognized compensation expense totaling approximately $1.2 million. Accordingly, all 2011 OPP Awards were automatically forfeited and the Company repaid employees an amount equal to $0.25 (which is equal to what they paid upon acceptance of the award) multiplied by the number of 2011 OPP Awards they received. On February 10, 2014, the Company completed and fully placed in-service The Avant at Reston Town Center development project comprised of 359 apartment units and retail space aggregating approximately 355,000 square feet located in Reston, Virginia. On February 18, 2014, the Company repaid at maturity the $747.5 million aggregate principal amount outstanding of its 3.625% Exchangeable Senior Notes due 2014 plus accrued and unpaid interest thereon.

Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2013

Real Estate and Accumulated Depreciation [Line Items]

Real Estate and Accumulated Depreciation Disclosure [Text Block]

Boston Properties Limited Partnership

Schedule 3—Real Estate and Accumulated Depreciation

December 31, 2013

(dollars in thousands)



				Original				Costs Capitalized Subsequent to Acquisition			Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total	Accumulated Depreciation		Year(s) Built/ Renovated	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances	Land		Building		Costs Capitalized Subsequent to Acquisition			Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total	Accumulated Depreciation		Year(s) Built/ Renovated	Depreciable Lives (Years)
767 Fifth Avenue (The General Motors Building)	Office	New York, NY	1,463,143	$	1,796,252	$	1,532,654	$	4,481		$	1,796,252	$	1,537,135	$	—	$	—	3,333,387	$	28,901	1968	(1)
Embarcadero Center	Office	San Francisco, CA	360,133	179,697		847,410		251,913			180,420		1,098,600		—		—		1,279,020	462,898		1970/1989	(1)
Prudential Center	Office	Boston, MA	—	92,077		734,594		294,125			92,328		1,012,537		15,931		—		1,120,796	389,841		1965/1993/2002	(1)
399 Park Avenue	Office	New York, NY	—	339,200		700,358		47,996			339,200		748,354		—		—		1,087,554	210,957		1961	(1)
The John Hancock Tower and Garage	Office	Boston, MA	652,933	219,543		667,884		57,420			219,616		724,812		419		—		944,847	78,366		1976	(1)
601 Lexington Avenue	Office	New York, NY	722,253	241,600		494,782		175,736			279,281		632,837		—		—		912,118	199,519		1977/1997	(1)
Times Square Tower	Office	New York, NY	—	165,413		380,438		47,167			159,694		433,324		—		—		593,018	132,227		2004	(1)
100 Federal Street	Office	Boston, MA	—	131,067		435,954		6,020			131,067		441,760		214		—		573,041	29,060		1971-1975	(1)
Carnegie Center	Office	Princeton, NJ	—	105,107		377,259		49,548			98,733		430,830		2,206		145		531,914	166,983		1983-1999	(1)
Atlantic Wharf	Office	Boston, MA	—	63,988		454,537		11,644			63,988		466,181		—		—		530,169	39,697		2011	(1)
Fountain Square	Office	Reston, VA	226,604	56,853		306,298		3,877			56,853		310,175		—		—		367,028	15,460		1986-1990	(1)
510 Madison Avenue	Office	New York, NY	—	103,000		253,665		6,309			103,000		259,974		—		—		362,974	15,901		2012	(1)
599 Lexington Avenue	Office	New York, NY	750,000	81,040		100,507		95,937			81,040		196,444		—		—		277,484	140,007		1986	(1)
South of Market and Democracy Tower	Office	Reston, VA	—	13,603		237,479		9,454			13,603		246,933		—		—		260,536	50,795		2008-2009	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—	18,789		148,451		47,332			18,789		195,783		—		—		214,572	21,339		1985-1989	(1)
Gateway Center	Office	San Francisco, CA	—	28,255		139,245		44,941			29,029		183,412		—		—		212,441	79,502		1984/1986/2002	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—	—		183,541		3,767			—		187,308		—		—		187,308	18,185		2011	(1)
Mountain View Research Park	Office	Mountain View, CA	—	106,162		76,137		2,196			106,162		78,333		—		—		184,495	3,013		1977-1981/2007-2013	(1)
One and Two Patriots Park	Office	Reston, VA	—	18,429		126,315		28,699			20,777		152,666		—		—		173,443	6,084		1987/1988/2012/2013	(1)
3200 Zanker Road	Office	San Jose, CA	—	36,705		82,863		23,501			36,705		102,620		3,744		—		143,069	22,994		1988	(1)
Reservoir Place	Office	Waltham, MA	—	18,605		92,619		23,371			19,099		115,496		—		—		134,595	52,216		1955/1987	(1)
505 9th Street	Office	Washington, DC	121,360	38,885		83,719		5,409			42,011		86,002		—		—		128,013	20,328		2007	(1)
Kingstowne Towne Center	Office	Alexandria, VA	33,338	18,021		109,038		578			18,021		109,616		—		—		127,637	26,508		2003-2006	(1)
1333 New Hampshire Avenue	Office	Washington, DC	—	34,032		85,660		3,619			34,032		89,279		—		—		123,311	29,574		1996	(1)
1330 Connecticut Avenue	Office	Washington, DC	—	25,982		82,311		11,673			25,982		93,984		—		—		119,966	28,822		1984	(1)
Weston Corporate Center	Office	Weston, MA	—	25,753		92,312		(123		)	25,854		92,088		—		—		117,942	10,921		2010	(1)
Capital Gallery	Office	Washington, DC	—	4,725		29,565		76,862			6,128		105,024		—		—		111,152	48,693		1981/2006	(1)



One Freedom Square	Office	Reston, VA	—	9,929	84,504	11,029		9,883	95,579	—	—	105,462	31,979	2000	(1)
One and Two Reston Overlook	Office	Reston, VA	—	16,456	66,192	22,217		16,456	88,409	—	—	104,865	30,481	1999	(1)
Five Cambridge Center	Office	Cambridge, MA	—	18,863	53,346	29,464		21,098	80,575	—	—	101,673	19,117	1981/1996	(1)
Seven Cambridge Center	Office	Cambridge, MA	—	3,457	97,136	210		3,457	97,346	—	—	100,803	47,101	2006	(1)
Two Freedom Square	Office	Reston, VA	—	13,930	77,739	7,604		13,866	85,407	—	—	99,273	36,361	2001	(1)
140 Kendrick Street	Office	Needham, MA	—	18,095	66,905	10,769		18,095	77,674	—	—	95,769	16,834	2000	(1)
Discovery Square	Office	Reston, VA	—	11,198	71,782	10,644		11,146	82,478	—	—	93,624	28,029	2001	(1)
Four Cambridge Center	Office	Cambridge, MA	—	19,104	52,078	11,693		20,741	62,134	—	—	82,875	10,739	1983/1998	(1)
77 CityPoint	Office	Waltham, MA	—	13,847	60,383	3,055		13,847	63,438	—	—	77,285	12,289	2008	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—	10,385	60,694	5,475		10,350	66,204	—	—	76,554	21,259	2003	(1)
North First Business Park	Office	San Jose, CA	—	58,402	13,069	3,987		23,371	16,198	35,889	—	75,458	10,208	1981	(1)
230 CityPoint	Office	Waltham, MA	—	13,189	49,823	11,485		13,189	61,308	—	—	74,497	17,363	1992	(1)
Seventeen Cambridge Center	Office	Cambridge, MA	—	18,080	51,262	—		18,080	51,262	—	—	69,342	1,080	2013	(1)
2440 West El Camino Real	Office	Mountain View, CA	—	16,741	51,285	502		16,741	51,787	—	—	68,528	4,390	1987/2003	(1)
Wisconsin Place	Office	Chevy Chase, MD	—	—	53,349	12,787		—	66,136	—	—	66,136	11,573	2009	(1)
Reston Corporate Center	Office	Reston, VA	—	9,135	50,857	2,735		9,496	53,231	—	—	62,727	20,642	1984	(1)
New Dominion Technology Park, Bldg. Two	Office	Herndon, VA	63,000	5,584	51,868	149		5,574	52,027	—	—	57,601	15,990	2004	(1)
Sumner Square	Office	Washington, DC	—	624	28,745	21,599		958	50,010	—	—	50,968	22,971	1985	(1)
New Dominion Technology Park, Bldg. One	Office	Herndon, VA	43,278	3,880	43,227	1,072		3,880	44,299	—	—	48,179	19,160	2001	(1)
191 Spring Street	Office	Lexington, MA	—	2,850	27,166	17,359		2,850	44,525	—	—	47,375	29,454	1971/1995	(1)
200 West Street	Office	Waltham, MA	—	16,148	24,983	5,907		16,148	30,890	—	—	47,038	14,432	1999	(1)
One Cambridge Center	Office	Cambridge, MA	—	134	25,110	18,952		134	44,062	—	—	44,196	24,666	1987	(1)
University Place	Office	Cambridge, MA	13,692	—	37,091	5,335		27	42,399	—	—	42,426	20,476	1985	(1)
2600 Tower Oaks Boulevard	Office	Rockville, MD	—	4,243	31,125	6,094		4,244	37,218	—	—	41,462	16,249	2001	(1)
Quorum Office Park	Office	Chelmsford, MA	—	3,750	32,454	3,974		4,762	35,416	—	—	40,178	12,493	2001	(1)
Three Patriots Park	Office	Reston, VA	—	3,594	32,977	1,353		3,594	34,330	—	—	37,924	12,217	2006	(1)
Mountain View Technology Park	Office	Mountain View, CA	—	20,359	13,640	182		20,359	13,822	—	—	34,181	761	1972	(1)
Eight Cambridge Center	Office	Cambridge, MA	—	850	25,042	6,502		822	31,572	—	—	32,394	10,835	1999	(1)
500 E Street	Office	Washington, DC	—	109	22,420	9,614		1,569	30,574	—	—	32,143	20,147	1987	(1)
Three Cambridge Center	Office	Cambridge, MA	—	174	12,200	7,987		772	19,589	—	—	20,361	9,651	1987	(1)
Ten Cambridge Center	Office	Cambridge, MA	—	1,299	12,943	4,011		1,868	16,385	—	—	18,253	11,019	1990	(1)
40 Shattuck Road	Office	Andover, MA	—	709	14,740	1,717		709	16,457	—	—	17,166	5,436	2001	(1)
201 Spring Street	Office	Lexington, MA	—	2,849	15,303	(1,253	)	2,849	14,050	—	—	16,899	5,868	1997	(1)
Lexington Office Park	Office	Lexington, MA	—	998	1,426	12,998		1,073	14,349	—	—	15,422	10,453	1982	(1)
92-100 Hayden Avenue	Office	Lexington, MA	—	594	6,748	7,090		619	13,813	—	—	14,432	9,804	1985	(1)
33 Hayden Avenue	Office	Lexington, MA	—	266	3,234	9,646		266	12,880	—	—	13,146	7,390	1979	(1)
181 Spring Street	Office	Lexington, MA	—	1,066	9,520	1,573		1,066	11,093	—	—	12,159	3,950	1999	(1)
91 Hartwell Avenue	Office	Lexington, MA	—	784	6,464	4,357		784	10,821	—	—	11,605	7,439	1985	(1)
195 West Street	Office	Waltham, MA	—	1,611	6,652	3,186		1,611	9,838	—	—	11,449	6,036	1990	(1)
7501 Boston Boulevard, Building Seven	Office	Springfield, VA	—	665	9,273	39		665	9,312	—	—	9,977	3,819	1997	(1)



Eleven Cambridge Center	Office	Cambridge, MA	—	121	5,535	4,318		121	9,853	—	—	9,974	7,119	1984	(1)
7435 Boston Boulevard, Building One	Office	Springfield, VA	—	392	3,822	3,202		486	6,930	—	—	7,416	5,422	1982	(1)
7450 Boston Boulevard, Building Three	Office	Springfield, VA	—	1,165	4,681	1,501		1,327	6,020	—	—	7,347	2,852	1987	(1)
8000 Grainger Court, Building Five	Office	Springfield, VA	—	366	4,282	2,350		453	6,545	—	—	6,998	5,071	1984	(1)
453 Ravendale Drive	Office	Mountain View, CA	—	5,477	1,090	230		5,477	1,320	—	—	6,797	142	1977	(1)
7500 Boston Boulevard, Building Six	Office	Springfield, VA	—	138	3,749	2,057		273	5,671	—	—	5,944	4,053	1985	(1)
7300 Boston Boulevard, Building Thirteen	Office	Springfield, VA	—	608	4,773	18		608	4,791	—	—	5,399	3,902	2002	(1)
7601 Boston Boulevard, Building Eight	Office	Springfield, VA	—	200	878	4,182		378	4,882	—	—	5,260	3,472	1986	(1)
Fourteen Cambridge Center	Office	Cambridge, MA	—	110	4,483	569		110	5,052	—	—	5,162	3,709	1983	(1)
8000 Corporate Court, Building Eleven	Office	Springfield, VA	—	136	3,071	1,133		687	3,653	—	—	4,340	2,300	1989	(1)
7375 Boston Boulevard, Building Ten	Office	Springfield, VA	—	23	2,685	826		47	3,487	—	—	3,534	2,235	1988	(1)
7374 Boston Boulevard, Building Four	Office	Springfield, VA	—	241	1,605	1,519		303	3,062	—	—	3,365	2,271	1984	(1)
7451 Boston Boulevard, Building Two	Office	Springfield, VA	—	249	1,542	1,000		535	2,256	—	—	2,791	2,083	1982	(1)
32 Hartwell Avenue	Office	Lexington, MA	—	168	1,943	214		168	2,157	—	—	2,325	1,478	1968-1979/1987	(1)
164 Lexington Road	Office	Billerica, MA	—	592	1,370	117		592	1,487	—	—	2,079	670	1982	(1)
17 Hartwell Avenue	Office	Lexington, MA	—	26	150	845		26	995	—	—	1,021	615	1968	(1)
Residences on The Avenue, 2221 I St., NW	Residential	Washington, DC	—	—	119,874	(32	)	—	119,842	—	—	119,842	7,948	2011	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—	3,529	54,891	1,543		3,529	56,434	—	—	59,963	3,591	2011	(1)
Cambridge Center Marriott	Hotel	Cambridge, MA	—	478	37,918	33,090		478	71,008	—	—	71,486	46,750	1986	(1)
Cambridge Center East Garage	Garage	Cambridge, MA	—	—	35,035	1,073		—	36,108	—	—	36,108	6,624	1984	(1)
Cambridge Center West Garage	Garage	Cambridge, MA	—	1,256	15,697	841		1,256	16,538	—	—	17,794	3,262	2006	(1)
Cambridge Center North Garage	Garage	Cambridge, MA	—	1,163	11,633	1,085		1,163	12,718	—	—	13,881	7,909	1990	(1)
250 West 55th Street	Development	New York, NY	—	—	—	816,578		15,889	44,227	—	756,462	816,578	483	N/A	N/A
Transbay Tower	Development	San Francisco, CA	—	—	—	255,406		—	—	—	255,406	255,406	—	N/A	N/A
680 Folsom Street	Development	San Francisco, CA	—	—	—	241,093		—	—	3,475	237,618	241,093	—	N/A	N/A
601 Massachusetts Avenue	Development	Washington, DC	—	—	—	121,694		—	—	—	121,694	121,694	—	N/A	N/A
535 Mission Street	Development	San Francisco, CA	—	—	—	113,274		—	—	—	113,274	113,274	—	N/A	N/A
The Avant at Reston Town Center Residential	Development	Reston, VA	—	—	—	107,022		12,741	55,701	—	38,580	107,022	160	N/A	N/A
Springfield Metro Center	Land	Springfield, VA	—	—	—	32,073		—	—	32,073	—	32,073	—	N/A	N/A
Plaza at Almaden	Land	San Jose, CA	—	—	—	29,003		—	—	29,003	—	29,003	—	N/A	N/A
Tower Oaks Master Plan	Land	Rockville, MD	—	—	—	28,976		—	—	28,976	—	28,976	—	N/A	N/A



Reston Signature Site	Land	Reston, VA	—				—		—		27,890		—		—		27,890		—		27,890		—		N/A	N/A
Prospect Hill	Land	Waltham, MA	—				—		—		24,197		—		667		23,530		—		24,197		—		N/A	N/A
Washingtonian North	Land	Gaithersburg, MD	—				—		—		18,290		—		—		18,290		—		18,290		—		N/A	N/A
6601 & 6605 Springfield Center Drive	Land	Springfield, VA	—				—		—		13,866		—		—		13,866		—		13,866		—		N/A	N/A
Waltham Office Center	Land	Waltham, MA	—				—		—		12,069		—		7,963		4,106		—		12,069		7,967		N/A	N/A
103 4th Avenue	Land	Waltham, MA	—				—		—		11,918		—		—		11,918		—		11,918		—		N/A	N/A
Cambridge Master Plan	Land	Cambridge, MA	—				—		—		11,153		—		—		11,153		—		11,153		—		N/A	N/A
Reston Gateway	Land	Reston, VA	—				—		—		9,682		—		—		9,682		—		9,682		—		N/A	N/A
Reston Eastgate	Land	Reston, VA	—				—		—		8,807		—		—		8,807		—		8,807		—		N/A	N/A
Crane Meadow	Land	Marlborough, MA	—				—		—		8,725		—		—		8,725		—		8,725		—		N/A	N/A
Broad Run Business Park	Land	Loudon County, VA	—				—		—		7,888		1,621		—		6,267		—		7,888		—		N/A	N/A
30 Shattuck Road	Land	Andover, MA	—				—		—		1,212		—		—		1,212		—		1,212		—		N/A	N/A
			$	4,449,734	(2	)	$	4,303,172	$	10,631,057	$	3,589,048	$	4,342,951	$	12,359,771	$	297,376	$	1,523,179	$	18,523,277	$	3,081,040

Note: Total Real Estate does not include Furniture, Fixtures and Equipment totaling approximately $25,164. Accumulated Depreciation does not include approximately $15,870 of accumulated depreciation related to Furniture, Fixtures and Equipment.

The aggregate cost and accumulated depreciation for tax purposes was approximately $16.5 billion and $2.9 billion, respectively.


(1)	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.


(2)	Includes the unamortized balance of the historical fair value adjustment totaling approximately $191.2 million.

Boston Properties Limited Partnership

Real Estate and Accumulated Depreciation

December 31, 2013

(dollars in thousands)

A summary of activity for real estate and accumulated depreciation is as follows:



	2013			2012			2011
Real Estate:
Balance at the beginning of the year	$	14,431,521		$	12,922,967		$	12,300,746
Additions to/improvements of real estate	4,410,622			1,602,583			668,084
Assets sold/written-off	(318,866		)	(94,029		)	(45,863		)
Balance at the end of the year	$	18,523,277		$	14,431,521		$	12,922,967
Accumulated Depreciation:
Balance at the beginning of the year	$	2,862,302		$	2,577,118		$	2,267,682
Depreciation expense	411,860			359,442			354,413
Assets sold/written-off	(193,122		)	(74,258		)	(44,977		)
Balance at the end of the year	$	3,081,040		$	2,862,302		$	2,577,118

Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

Summary Of Significant Accounting Policies Summary Of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Real Estate

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:




Land improvements		25 to 40 years
Buildings and improvements		10 to 40 years
Tenant improvements		Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment		3 to 7 years

Cash and Cash Equivalents

Cash Held in Escrows

Escrows include amounts established pursuant to various agreements for security deposits, property taxes, insurance and other costs.

Investments in Securities

Tenant and Other Receivables

Tenant and other accounts receivable, other than accrued rents receivable, are expected to be collected within one year.

Deferred Charges

Investments in Unconsolidated Joint Ventures

Revenue Recognition



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2014	$	23,669	$	61,700
2015	22,758		55,207
2016	20,576		52,461
2017	12,279		40,346
2018	8,637		37,774

The Company's parking revenues are derived from leases, monthly parking and transient parking. The Company recognizes parking revenue as earned.

Ground Leases




Years Ending December 31,	(in thousands)
2014	$	13,184
2015	13,507
2016	13,732
2017	13,963
2018	14,198
Thereafter	899,187

Earnings Per Common Unit

Fair Value of Financial Instruments



	December 31, 2013					December 31, 2012
	Carrying Amount			Estimated Fair Value		Carrying Amount			Estimated Fair Value
Mortgage notes payable	$	4,449,734		$	4,545,283	$	3,102,485		$	3,256,940
Mezzanine notes payable	311,040			311,064		—			—
Unsecured senior notes	5,835,854			6,050,517		4,639,528			5,162,486
Unsecured exchangeable senior notes	744,880		(1)	750,266		1,170,356		(1)	1,278,554
Total	$	11,341,508		$	11,657,130	$	8,912,369		$	9,697,980

_____________


(1)	Includes the net adjustment for the equity component allocation totaling approximately $2.4 million and $25.5 million at December 31, 2013 and December 31, 2012, respectively.

Derivatives Instruments and Hedging Activities

Derivative Instruments and Hedging Activities

Income Taxes

The following table reconciles GAAP net income attributable to Boston Properties Limited Partnership to taxable income:



	For the year ended December 31,
	2013			2012			2011
	(in thousands)
Net income attributable to Boston Properties Limited Partnership	$	841,516		$	334,601		$	317,152
Straight-line rent adjustments	(82,904		)	(89,982		)	(87,773		)
Book/Tax differences from depreciation and amortization	174,384			106,862			118,728
Book/Tax differences on gains/losses from capital transactions	(138,300		)	(24,958		)	(45,056		)
Book/Tax differences from stock-based compensation	46,935			22,035			937
Other book/tax differences, net	7,835			42,004			50,022
Taxable income	$	849,466		$	390,562		$	354,010

Stock-Based Employee Compensation Plans

Use of Estimates in the Preperation of Financial Statements

Use of Estimates in the Preparation of Financial Statements

Recent Accounting Pronouncements

Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Fair Value, by Balance Sheet Grouping [Table Text Block]



	December 31, 2013					December 31, 2012
	Carrying Amount			Estimated Fair Value		Carrying Amount			Estimated Fair Value
Mortgage notes payable	$	4,449,734		$	4,545,283	$	3,102,485		$	3,256,940
Mezzanine notes payable	311,040			311,064		—			—
Unsecured senior notes	5,835,854			6,050,517		4,639,528			5,162,486
Unsecured exchangeable senior notes	744,880		(1)	750,266		1,170,356		(1)	1,278,554
Total	$	11,341,508		$	11,657,130	$	8,912,369		$	9,697,980

_____________


(1)	Includes the net adjustment for the equity component allocation totaling approximately $2.4 million and $25.5 million at December 31, 2013 and December 31, 2012, respectively.

Gaap Reconciliation Of Net Income To Taxable Income, Table [Table Text Block]

The following table reconciles GAAP net income attributable to Boston Properties Limited Partnership to taxable income:



	For the year ended December 31,
	2013			2012			2011
	(in thousands)
Net income attributable to Boston Properties Limited Partnership	$	841,516		$	334,601		$	317,152
Straight-line rent adjustments	(82,904		)	(89,982		)	(87,773		)
Book/Tax differences from depreciation and amortization	174,384			106,862			118,728
Book/Tax differences on gains/losses from capital transactions	(138,300		)	(24,958		)	(45,056		)
Book/Tax differences from stock-based compensation	46,935			22,035			937
Other book/tax differences, net	7,835			42,004			50,022
Taxable income	$	849,466		$	390,562		$	354,010

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

The following table summarizes the scheduled amortization of the Company's acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2014	$	23,669	$	61,700
2015	22,758		55,207
2016	20,576		52,461
2017	12,279		40,346
2018	8,637		37,774

The following table summarizes the scheduled amortization of the Company's acquired in-place lease intangibles for each of the five succeeding years (in thousands).



	Acquired In-Place Lease Intangibles
2014	$	91,903
2015	66,716
2016	55,083
2017	41,106
2018	36,306

Schedule Of Future Contractual Minimum Lease Payments Under Non-Cancelable Ground Leases [Table Text Block]




Years Ending December 31,	(in thousands)
2014	$	13,184
2015	13,507
2016	13,732
2017	13,963
2018	14,198
Thereafter	899,187

Property, Plant and Equipment [Table Text Block]

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:




Land improvements		25 to 40 years
Buildings and improvements		10 to 40 years
Tenant improvements		Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment		3 to 7 years

Real Estate (Tables)

12 Months Ended

Dec. 31, 2013

Real Estate Properties [Line Items]

Schedule of Property Subject to or Available for Operating Lease [Table Text Block]

Real estate consisted of the following at December 31 (in thousands):



	2013			2012
Land	$	4,342,951		$	2,496,547
Land held for future development	297,376			271,189
Buildings and improvements	10,742,370			9,191,497
Tenant improvements	1,617,401			1,435,508
Furniture, fixtures and equipment	25,164			23,441
Construction in progress	1,523,179			1,036,780
Total	18,548,441			14,454,962
Less: Accumulated depreciation	(3,096,910		)	(2,876,983		)
	$	15,451,531		$	11,577,979

Pro Forma in Connection With Acquisition



Pro Forma (Unaudited)	Year ended December 31,
(in thousands, except per unit data)	2013		2012
Total revenue	$	2,257,098	$	2,149,391
Income from continuing operations	$	314,307	$	642,640
Net income attributable to Boston Properties Limited Partnership	$	452,813	$	710,690
Basic earnings per unit:
Net income per unit attributable to Boston Properties Limited Partnership	$	2.68	$	4.21
Diluted earnings per unit:
Net income per unit attributable to Boston Properties Limited Partnership	$	2.67	$	4.20

Summary of the Discontinued Operations



	For the year ended December 31,
	2013			2012		2011
	(in thousands)
Total revenue	$	20,138		$	32,607	$	36,734
Expenses
Operating	6,996			12,038		13,818
Depreciation and amortization	4,760			8,169		9,442
Total expenses	11,756			20,207		23,260
Operating income	8,382			12,400		13,474
Other expense
Interest expense	360			2,594		2,598
Income from discontinued operations attributable to Boston Properties Limited Partnership	$	8,022		$	9,806	$	10,876

Gains on sales of real estate from discontinued operations attributable to Boston Properties Limited Partnership	$	115,459		$	38,445	$	—
Gain on forgiveness of debt from discontinued operations attributable to Boston Properties Limited Partnership	$	20,736		$	—	$	—
Impairment loss from discontinued operations attributable to Boston Properties Limited Partnership	$	(2,852	)	$	—	$	—

Mountain View Research And Technology Parks [Member]

Real Estate Properties [Line Items]

Schedule of Allocation of the Aggregate Purchase Price of Acquisition

The following table summarizes the allocation of the aggregate purchase price of Mountain View Research Park and Mountain View Technology Park at the date of acquisition (in thousands) in accordance with the guidance in ASC 805 "Business Combinations."



Land	$	126,521
Building and improvements	82,451
Tenant improvements	7,326
In-place lease intangibles	23,279
Above-market rents	843
Below-market rents	(7,336		)
Net assets acquired	$	233,084

767 5th Avenue (The General Motors Building) [Member]

Real Estate Properties [Line Items]

Schedule of Allocation of the Aggregate Purchase Price of Acquisition

The following table summarizes the allocation of the aggregate purchase price of 767 Fifth Avenue (the General Motors Building) at the date of consolidation on May 31, 2013 (in thousands) in accordance with the guidance in ASC 805 "Business Combinations."



Real estate and related intangibles recorded upon consolidation
Land	$	1,796,252
Building and improvements	1,447,446
Tenant improvements	85,208
In-place lease intangibles	357,781
Above market rents	101,897
Below market rents	(239,641		)
Above market assumed debt adjustments	(192,943		)
	$	3,356,000
Debt recorded upon consolidation
Mortgage notes payable	$	(1,300,000	)
Mezzanine notes payable	(306,000		)
Members' notes payable	(450,000		)	(1)
	$	(2,056,000	)

Working capital recorded upon consolidation
Cash and cash equivalents	$	79,468
Cash held in escrows	2,403
Tenant and other receivables	7,104
Prepaid expenses and other assets	4,269
Accounts payable and accrued expenses	(2,418		)
Accrued interest payable	(182,369		)	(2)
Other liabilities	(6,304		)
	$	(97,847	)
Noncontrolling interest recorded upon consolidation
Noncontrolling interests	$	(520,000	)
Noncontrolling interests - working capital	39,139
	$	(480,861	)

Net assets recorded upon consolidation	$	721,292

_______________

(1) The Company's member loan totaling $270.0 million eliminates in consolidation.

(2) The Company's share of the accrued interest payable on the members' loans totaling approximately $105.5 million eliminates in consolidation.

- Definition

Tabular disclosure of disposal groups, which may include the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss), amounts of revenues and pretax profit or loss reported in discontinued operations, the classification and carrying value of the assets and liabilities comprising the disposal group, and the segment in which the disposal group was reported. Also may include the amount of adjustments to amounts previously reported in discontinued operations such as resolution of contingencies arising from the disposal transaction or the operations of the component prior to disposal.

+ References + Details

Deferred Charges (Tables)

12 Months Ended

Dec. 31, 2013

Deferred Charges [Abstract]

Deferred Charges

Deferred charges consisted of the following at December 31, (in thousands):



	2013			2012
Leasing costs, including lease related intangibles	$	1,183,204		$	790,740
Financing costs	76,798			90,682
	1,260,002			881,422
Less: Accumulated amortization	(375,552		)	(293,187		)
	$	884,450		$	588,235

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

The following table summarizes the scheduled amortization of the Company's acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2014	$	23,669	$	61,700
2015	22,758		55,207
2016	20,576		52,461
2017	12,279		40,346
2018	8,637		37,774

The following table summarizes the scheduled amortization of the Company's acquired in-place lease intangibles for each of the five succeeding years (in thousands).



	Acquired In-Place Lease Intangibles
2014	$	91,903
2015	66,716
2016	55,083
2017	41,106
2018	36,306

Investments in Unconsolidated Joint Ventures (Tables)

12 Months Ended

Dec. 31, 2013

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at December 31, 2013:



Entity	Properties	Nominal % Ownership
Square 407 Limited Partnership	Market Square North	50.0	%
The Metropolitan Square Associates LLC	Metropolitan Square	51.0	%
BP/CRF 901 New York Avenue LLC	901 New York Avenue	25.0	%	(1)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.3	%	(2)
RBP Joint Venture LLC	N/A	50.0	%	(3)
Boston Properties Office Value-Added Fund, L.P.	N/A	39.5	%	(4)
Annapolis Junction NFM, LLC	Annapolis Junction	50.0	%	(5)
2 GCT Venture LLC	N/A	60.0	%	(6)
540 Madison Venture LLC	540 Madison Avenue	60.0	%
125 West 55^th Street Venture LLC	N/A	60.0	%	(7)
500 North Capitol LLC	500 North Capitol Street, NW	30.0	%

_______________


(1)	The Company’s economic ownership can increase based on the achievement of certain return thresholds.


(2)	The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land, parking and infrastructure of the project.


(3)	Eighth Avenue and 46th Street was sold on July 19, 2013.


(4)	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of December 31, 2013, the investment is comprised of undistributed cash.


(5)	Comprised of two buildings, one building under construction and two undeveloped land parcels.


(6)	Two Grand Central Tower was sold on October 25, 2011. As of December 31, 2013, the investment is comprised of undistributed cash.


(7)	125 West 55th Street was sold on May 30, 2013. As of December 31, 2013, the investment is comprised of undistributed cash.

Balance Sheets Of The Unconsolidated Joint Ventures

The combined summarized balance sheets of the unconsolidated joint ventures are as follows:



	December 31, 2013			December 31, 2012
	(in thousands)
ASSETS
Real estate and development in process, net	$	924,297		$	4,494,971
Other assets	163,149			673,716
Total assets	$	1,087,446		$	5,168,687
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable	$	749,732		$	3,039,922
Other liabilities	28,830			792,888
Members’/Partners’ equity	308,884			1,335,877
Total liabilities and members’/partners’ equity	$	1,087,446		$	5,168,687
Company’s share of equity	$	154,726		$	787,941
Basis differentials (1)	(28,642		)	(128,025		)
Carrying value of the Company’s investments in unconsolidated joint ventures	$	126,084		$	659,916

_______________

(1)

Statements Of Operations Of The Joint Ventures

The combined summarized statements of operations of the joint ventures are as follows:



	For the year ended December 31,
	2013			2012			2011
	(in thousands)
Total revenue (1)	$	311,548		$	564,205		$	589,294
Expenses
Operating	105,319			162,665			170,404
Depreciation and amortization	86,088			163,134			190,437
Impairment losses	—			—			40,468
Total expenses	191,407			325,799			401,309
Operating income	120,141			238,406			187,985
Other income (expense)
Interest expense	(112,535		)	(224,645		)	(228,494		)
Losses from early extinguishments of debt	(1,677		)	—			—
Income (loss) from continuing operations	5,929			13,761			(40,509		)
Gains on sales of real estate	14,207			990			—
Net income (loss)	$	20,136		$	14,751		$	(40,509	)

Company’s share of net income (loss)	$	4,612		$	6,863		$	(25,374	)
Gains on sales of real estate	54,501			—			46,166
Basis differential	(1,017		)	1,732			27,226
Elimination of inter-entity interest on partner loan	16,978			40,483			37,878
Income from unconsolidated joint ventures	$	75,074		$	49,078		$	85,896
Gains on consolidation of joint ventures	$	385,991		$	—		$	—

_______________

(1)

Mortgage Notes Payable Schedule of Aggregate Principal Payments on Mortgage Notes (Tables)

12 Months Ended

Dec. 31, 2013

Mortgage Notes Payable [Abstract]

Schedule of Aggregate Principal Payments On Mortgage Notes [Table Text Block]

Contractual aggregate principal payments of mortgage notes payable at December 31, 2013 are as follows:



	Principal Payments
	(in thousands)
2014	$	87,759
2015	26,182
2016	608,879
2017	2,821,750
2018	18,633
Thereafter	695,327
Total aggregate principal payments	4,258,530
Unamortized balance of historical fair value adjustments	191,204
Total carrying value of mortgage notes payable	$	4,449,734

Unsecured Senior Notes (Tables)

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Schedule of Senior Notes

The following summarizes the unsecured senior notes outstanding as of December 31, 2013 (dollars in thousands):



	Coupon/ Stated Rate		Effective Rate(1)		Principal Amount			Maturity Date(2)
12 Year Unsecured Senior Notes	5.625	%	5.693	%	$	300,000		April 15, 2015
12 Year Unsecured Senior Notes	5.000	%	5.194	%	250,000			June 1, 2015
10 Year Unsecured Senior Notes	5.875	%	5.967	%	700,000			October 15, 2019
10 Year Unsecured Senior Notes	5.625	%	5.708	%	700,000			November 15, 2020
10 Year Unsecured Senior Notes	4.125	%	4.289	%	850,000			May 15, 2021
7 Year Unsecured Senior Notes	3.700	%	3.853	%	850,000			November 15, 2018
11 Year Unsecured Senior Notes	3.850	%	3.954	%	1,000,000			February 1, 2023
10.5 Year Unsecured Senior Notes	3.125	%	3.279	%	500,000			September 1, 2023
10.5 Year Unsecured Senior Notes	3.800	%	3.916	%	700,000			February 1, 2024

Total principal					5,850,000
Net unamortized discount					(14,146		)
Total					$	5,835,854

_______________


(1)	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.


(2)	No principal amounts are due prior to maturity.

Unsecured Exchangeable Senior Notes (Tables)

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Schedule of Unsecured Exchangeable Senior Notes

The following summarizes the unsecured exchangeable senior notes outstanding as of December 31, 2013 (dollars in thousands):



	Coupon/ Stated Rate		Effective Rate(1)		Exchange Rate		Principal Amount			First Optional Redemption Date by the Company	Maturity Date
3.625% Exchangeable Senior Notes	3.625	%	4.037	%	8.6974	(2)	$	747,500		N/A	February 15, 2014
Net unamortized discount							(182		)
Adjustment for the equity component allocation, net of accumulated amortization							(2,438		)
Total							$	744,880

_______________


(1)	Yield on issuance date including the effects of discounts on the notes but excluding the effects of the adjustment for the equity component allocation.

(2)

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

+ Details

Noncontrolling Interests (Tables)

12 Months Ended

Dec. 31, 2013

Noncontrolling Interest [Abstract]

Schedule of Redeemable Interest in Property Partnerships [Table Text Block]



Balance at December 31, 2011	$	—
Acquisition-date fair value of redeemable interest	98,787
Net loss	(719		)
Distributions	(3,032		)
Adjustment to reflect redeemable interest at redemption value	2,522
Balance at December 31, 2012	97,558
Net loss	(1,839		)
Distributions	(4,585		)
Adjustment to reflect redeemable interest at redemption value	8,475
Balance at December 31, 2013	$	99,609

Schedule Of Preferred Units

The following table reflects the activity of the noncontrolling interests—redeemable preferred units for the years ended December 31, 2013, 2012 and 2011 (in thousands):



Balance at December 31, 2010	$	125,765
Net income	3,339
Distributions	(3,339		)
Reallocation of partnership interest	19,719
Balance at December 31, 2011	145,484
Issuance of redeemable preferred units (Series Four Preferred Units)	79,405
Net income	3,497
Distributions	(3,497		)
Redemption of redeemable preferred units (Series Four Preferred Units)	(18,329		)
Reallocation of partnership interest (1)	(7,182		)
Balance at December 31, 2012	199,378
Net income	6,046
Distributions	(6,046		)
Redemption of redeemable preferred units (Series Four Preferred Units)	(43,070		)
Reallocation of partnership interest (1)	(50,562		)
Balance at December 31, 2013	$	105,746


(1)	Includes the conversion of 329,881 and 117,047 Series Two Preferred Units into 432,914 and 153,605 OP Units during the years ended December 31, 2013 and 2012, respectively.

Noncontrolling Interests-Redeemable Common Units

The following table reflects the activity of the noncontrolling interests—redeemable common units for the years ended December 31, 2013, 2012 and 2011 (in thousands):



Balance at December 31, 2010	$	1,801,592
Contributions	23,379
Net income	36,250
Distributions	(39,132		)
Conversion of redeemable partnership units	(85,498		)
Unearned compensation	(1,952		)
Accumulated other comprehensive loss	297
Adjustment to reflect redeemable partnership units at redemption value	74,183
Balance at December 31, 2011	1,809,119
Contributions	24,588
Net income	35,200
Distributions	(41,434		)
Conversion of redeemable partnership units	(34,621		)
Unearned compensation	(883		)
Accumulated other comprehensive loss	273
Adjustment to reflect redeemable partnership units at redemption value	44,280
Balance at December 31, 2012	1,836,522
Contributions	26,398
Net income	84,236
Distributions	(83,448		)
Conversion of redeemable partnership units	(30,291		)
Unearned compensation	1,472
Accumulated other comprehensive loss	252
Adjustment to reflect redeemable partnership units at redemption value	(124,923		)
Balance at December 31, 2013	$	1,710,218

Noncontrolling Interests-Property Partnerships

The following table reflects the activity of the noncontrolling interests—property partnerships for the years ended December 31, 2013, 2012 and 2011 (in thousands):



Balance at December 31, 2010	$	(614	)
Net income	1,558
Distributions	(2,007		)
Balance at December 31, 2011	(1,063		)
Net income	1,989
Distributions	(2,890		)
Balance at December 31, 2012	(1,964		)
Fair value of capital recorded upon consolidation	480,861
Capital contributions	257,564
Net loss	(5,290		)
Distributions	(5,039		)
Balance at December 31, 2013	$	726,132

Partners' Capital Schedule Of Changes In Partners Capital Unit (Tables)

156 Months Ended

Dec. 31, 2013

Partners' Capital [Abstract]

Schedule Of Changes In Partners Capital Unit [Table Text Block]



	General Partner Units	Limited Partner Units	Total Partners’ Capital Units
Outstanding at December 31, 2010	1,610,941	138,588,164	140,199,105
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	42	6,314	6,356
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	2,112	320,499	322,611
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	19,112	2,900,211	2,919,323
Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs	30,508	4,629,708	4,660,216
Outstanding at December 31, 2011	1,662,715	146,444,896	148,107,611
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	57	7,349	7,406
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	216	27,816	28,032
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	8,541	1,102,119	1,110,660
Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs	18,051	2,329,449	2,347,500
Outstanding at December 31, 2012	1,689,580	149,911,629	151,601,209
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	50	6,392	6,442
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	207	26,686	26,893
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	7,158	922,283	929,441
Units issued to Boston Properties, Inc. related to Common Stock issued in connection with the exchange of Exchangeable Senior Notes	3,227	415,889	419,116
Outstanding at December 31, 2013	1,700,222	151,282,879	152,983,101

Partners' Capital Schedule of changes in Series B Preferred Units (Tables)

12 Months Ended

Dec. 31, 2013

Statement of Partners' Capital [Abstract]

Schedule of changes in Series B Preferred Units [Table Text Block]



Balance at December 31, 2012	$	—
Issuance of Series B Preferred Units	193,623
Net income	8,057
Distributions	(8,057		)
Balance at December 31, 2013	$	193,623

Future Minimum Rents (Tables)

12 Months Ended

Dec. 31, 2013

Future Minimum Rents [Abstract]

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]



Years Ending December 31,	(in thousands)
2014	$	1,716,754
2015	1,706,282
2016	1,660,890
2017	1,510,645
2018	1,342,157
Thereafter	6,674,466

Segment Information (Tables)

12 Months Ended

Dec. 31, 2013

Segment Reporting [Abstract]

Schedule Of Segment Information By Geographic Area And Property Type

Information by geographic area and property type (dollars in thousands):

For the year ended December 31, 2013:



	Boston			New York			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	665,991		$	725,566		$	214,755		$	381,359		$	1,987,671
Office/Technical	22,617			—			17,259			15,649			55,525
Residential	4,395			—			—			17,923			22,318
Hotel	40,330			—			—			—			40,330
Total	733,333			725,566			232,014			414,931			2,105,844
% of Grand Totals	34.82		%	34.46		%	11.02		%	19.70		%	100.00		%
Rental Expenses:
Class A Office	259,997			251,640			77,905			126,507			716,049
Office/Technical	6,879			—			3,708			4,190			14,777
Residential	1,823			—			—			10,307			12,130
Hotel	28,447			—			—			—			28,447
Total	297,146			251,640			81,613			141,004			771,403
% of Grand Totals	38.52		%	32.62		%	10.58		%	18.28		%	100.00		%
Net operating income	$	436,187		$	473,926		$	150,401		$	273,927		$	1,334,441
% of Grand Totals	32.69		%	35.51		%	11.27		%	20.53		%	100.00		%

For the year ended December 31, 2012:



	Boston			New York			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	617,652		$	543,194		$	208,177		$	346,402		$	1,715,425
Office/Technical	22,460			—			494			16,264			39,218
Residential	3,936			—			—			16,632			20,568
Hotel	37,915			—			—			—			37,915
Total	681,963			543,194			208,671			379,298			1,813,126
% of Grand Totals	37.61		%	29.96		%	11.51		%	20.92		%	100.00		%
Rental Expenses:
Class A Office	242,904			187,987			75,542			111,049			617,482
Office/Technical	6,499			—			149			3,966			10,614
Residential	1,675			—			—			9,317			10,992
Hotel	28,120			—			—			—			28,120
Total	279,198			187,987			75,691			124,332			667,208
% of Grand Totals	41.85		%	28.18		%	11.34		%	18.63		%	100.00		%
Net operating income	$	402,765		$	355,207		$	132,980		$	254,966		$	1,145,918
% of Grand Totals	35.15		%	31.00		%	11.60		%	22.25		%	100.00		%

For the year ended December 31, 2011:



	Boston			New York			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	537,743		$	521,439		$	207,003		$	340,470		$	1,606,655
Office/Technical	25,349			—			—			16,236			41,585
Residential	985			—			—			5,632			6,617
Hotel	34,529			—			—			—			34,529
Total	598,606			521,439			207,003			362,338			1,689,386
% of Grand Totals	35.43		%	30.87		%	12.25		%	21.45		%	100.00		%
Rental Expenses:
Class A Office	206,469			181,269			72,122			95,804			555,664
Office/Technical	7,245			—			—			4,280			11,525
Residential	521			—			—			4,958			5,479
Hotel	26,128			—			—			—			26,128
Total	240,363			181,269			72,122			105,042			598,796
% of Grand Totals	40.14		%	30.27		%	12.05		%	17.54		%	100.00		%
Net operating income	$	358,243		$	340,170		$	134,881		$	257,296		$	1,090,590
% of Grand Totals	32.85		%	31.19		%	12.37		%	23.59		%	100.00		%

Schedule Of Reconciliation Of Net Operating Income To Net Income

The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership:



	Year ended December 31,
		2013		2012			2011
Net Operating Income		$	1,334,441	$	1,145,918		$	1,090,590
Add:
Development and management services income		29,695		34,060			33,406
Income from unconsolidated joint ventures		75,074		49,078			85,896
Gains on consolidation of joint ventures		385,991		—			—
Interest and other income		8,310		10,091			5,358
Gains (losses) from investments in securities		2,911		1,389			(443		)
Gains (losses) from early extinguishments of debt		122		(4,453		)	(1,494		)
Income from discontinued operations		8,022		9,806			10,876
Gains on sales of real estate from discontinued operations		115,459		38,445			—
Gain on forgiveness of debt from discontinued operations		20,736		—			—
Less:
General and administrative expense		115,329		90,129			87,101
Transaction costs		1,744		3,653			1,987
Depreciation and amortization expense		552,589		437,692			421,519
Interest expense		446,880		410,970			391,533
Impairment loss		4,401		—			—
Impairment loss from discontinued operations		2,852		—			—
Noncontrolling interest in property partnerships		1,347		3,792			1,558
Noncontrolling interest—redeemable preferred units		14,103		3,497			3,339
Net income attributable to Boston Properties Limited Partnership		$	841,516	$	334,601		$	317,152

Earnings Per Common Unit (Tables)

12 Months Ended

Dec. 31, 2013

Earnings Per Share [Abstract]

Computation Of Basic And Diluted Earnings Per Unit

Included in the number of units (the denominator) below are approximately 16,925,000, 17,649,000 and 18,793,000 redeemable common units for the years ended December 31, 2013, 2012 and 2011, respectively.



	For the Year Ended December 31, 2013
	Income (Numerator)			Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties Limited Partnership	$	700,151		169,126	$	4.14
Discontinued operations attributable to Boston Properties Limited Partnership	141,365			—	0.84
Allocation of undistributed earnings to participating securities	(178		)	—	(0.01		)
Net income attributable to Boston Properties Limited Partnership	$	841,338		169,126	$	4.97
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—			320	—
Diluted Earnings:
Net income	$	841,338		169,446	$	4.97



	For the Year Ended December 31, 2012
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties Limited Partnership	$	286,350	167,769	$	1.70
Discontinued operations attributable to Boston Properties Limited Partnership	48,251		—	0.29
Net income attributable to Boston Properties Limited Partnership	$	334,601	167,769	$	1.99
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—		591	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership	$	334,601	168,360	$	1.99

	For the Year Ended December 31, 2011
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties Limited Partnership	$	306,276	164,486	$	1.86
Discontinued operations attributable to Boston Properties Limited Partnership	10,876		—	0.07
Net income attributable to Boston Properties Limited Partnership	$	317,152	164,486	$	1.93
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—		525	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership	$	317,152	165,011	$	1.92

Stock Option and Incentive Plan Stock Option and Incentive Plan and Stock Purchase Plan (Tables)

12 Months Ended

Dec. 31, 2013

Stock Option and Incentive Plan and Stock Purchase Plan [Abstract]

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]



	Shares		Weighted Average Exercise Price
Outstanding at December 31, 2010	324,938		$	32.65
Granted	146,844		$	92.71
Exercised	(316,159	)	$	32.63
Canceled	—		$	—
Outstanding at December 31, 2011	155,623		$	89.35
Granted	186,007		$	107.23
Exercised	(22,823	)	$	72.42
Canceled	(24,280	)	$	100.15
Outstanding at December 31, 2012	294,527		$	101.06
Granted	252,220		$	104.50
Exercised	—		$	—
Canceled	—		$	—
Special dividend adjustment	12,076		$	100.44
Outstanding at December 31, 2013	558,823		$	100.43

Schedule of Stock Options Outstanding [Table Text Block]

The following table summarizes information about stock options outstanding at December 31, 2013:



Options Outstanding						Options Exercisable
Exercise Prices		Number Outstanding at 12/31/13	Remaining Contractual Life	Exercise Price		Number Exercisable at 12/31/13	Exercise Price
$	90.71	131,837	7.1 years	$	90.71	80,240	$	90.71
$	99.94	51,971	9.3 years	$	99.94	—	$	—
$	102.83	205,821	9.1 years	$	102.83	48,026	$	102.83
$	105.25	169,194	8.1 years	$	105.25	71,602	$	105.25

Selected Interim Financial Information (unaudited) (Tables)

12 Months Ended

Dec. 31, 2013

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]



	2013 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per unit amounts)
Total revenue	$	477,826	$	510,033	$	571,481	$	576,199
Income from continuing operations	$	44,445	$	505,396	$	84,348	$	81,412
Net income attributable to Boston Properties Limited Partnership	$	60,923	$	505,189	$	174,140	$	101,264
Income attributable to Boston Properties Limited Partnership per unit—basic	$	0.36	$	2.97	$	1.03	$	0.60
Income attributable to Boston Properties Limited Partnership per unit—diluted	$	0.36	$	2.96	$	1.02	$	0.60



	2012 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per unit amounts)
Total revenue	$	438,722	$	466,197	$	464,220	$	478,047
Income from continuing operations	$	55,133	$	96,836	$	65,375	$	76,295
Net income attributable to Boston Properties Limited Partnership	$	56,542	$	136,561	$	66,234	$	75,264
Income attributable to Boston Properties Limited Partnership per unit—basic	$	0.34	$	0.81	$	0.39	$	0.45
Income attributable to Boston Properties Limited Partnership per unit—diluted	$	0.34	$	0.81	$	0.39	$	0.45

Organization (Details) ft² in Millions	3 Months Ended	12 Months Ended
Organization (Details) ft² in Millions	Mar. 31, 2014 shares $ / shares	Dec. 31, 2013 a ft² Real_Estate_Properties Vehicles yr shares	Dec. 31, 2012 shares	Aug. 29, 2013 $ / shares
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)		89.50%	89.00%
Restriction on redemption of OP units from date of issuance (years) \| yr		1
One OP unit is equivalent to one share of Common Stock (in shares) \| shares		1
OP unit conversion rate (in shares) \| shares		1
Number of series of preferred units outstanding \| shares	3
Number of vehicles in structured parking \| Vehicles		45,234
Area of parking (in square feet) \| ft²		15.4
Area of undeveloped land parcels owned (in acres) \| a		503.6
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties		175
Net Rentable Area \| ft²		44.4
Total Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties		9
Net Rentable Area \| ft²		2.9
Total Office Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties		167
Class A Office Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties		128
Office Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties		8
Office/Technical Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties		39
Hotel Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties		1
Retail Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties		4
Residential Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties		3
Residential Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties		1
Series Four Preferred Units [Member]
Real Estate Properties [Line Items]
Preferred Units Liquidation Preference \| $ / shares	$ 50.00			$ 50.00
Quarterly distribution to Series Four Preferred Units \| $ / shares	$ 0.25
Series Four Preferred Units Annual Dividend Payable Rate	2.00%
Series Two Preferred Units [Member]
Real Estate Properties [Line Items]
Preferred Units Liquidation Preference \| $ / shares	$ 50.00
OP Units for each Preferred Unit (in shares) \| shares	1.312336
Series B Cumulative Redeemable Preferred Stock [Member]
Real Estate Properties [Line Items]
Preferred Stock, Shares Outstanding \| shares	80,000	80,000	0
Preferred Stock, Dividend Rate, Percentage	5.25%
Series B Preferred Units [Member]
Real Estate Properties [Line Items]
Preferred Stock, Shares Outstanding \| shares	80,000

Summary Of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2013 USD ($) yr	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)
Accounting Policies [Abstract]
Probable Sale Term of Property After Classified As Held For Sale (Years) \| yr	1
Maximum Period After Construction The Company Considers A Construction Project As Substantially Completed (In Years) \| yr	1
Interest Costs Capitalized	$ 68,152,000	$ 44,278,000	$ 48,178,000
Salaries And Related Costs Capitalized	7,700,000	7,100,000	6,500,000
Cash FDIC Insured Limit	250,000
Separate Unrestricted Cash For Deferred Compensation Plan.	16,600,000	12,200,000
Gains (losses) from investments in securities	2,911,000	1,389,000	(443,000)
Internal Leasing Salaries And Related Costs Capitalized	5,100,000	5,600,000	4,400,000
Straight Line Rent Adjustments	(65,800,000)	(77,600,000)	(77,000,000)
Above And Below Market Rent Adjustments	$ 28,000,000	14,600,000	10,800,000
Ground Lease Expiration Date, Maximum	2068
Net Difference Between Tax Basis And Company's Assets And Liabilities.	$ 900,000,000	100,000,000
Misstatement of real estate operating expense	3,200,000
Interest and other income	8,310,000	10,091,000	5,358,000
Reclassification between general and administrative expense and real estate operating expenses	$ 8,100,000	$ 7,700,000	$ 7,500,000

Summary Of Significant Accounting Policies Schedule of Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2013
Land Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	25 years
Land Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	40 years
Building and improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	10 years
Building and improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	40 years
Tenant Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, description	Shorter of useful life or terms of related lease
Furniture, fixtures and equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	3 years
Furniture, fixtures and equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	7 years

Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($)
$ in Thousands

Dec. 31, 2013

Dec. 31, 2012

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable

$ 4,449,734

$ 3,102,485

Mezzanine notes payable

311,040

Unsecured Senior Notes

5,835,854

4,639,528

Unsecured exchangeable senior notes

744,880

1,170,356

Total

4,258,530

Impact of accounting pronouncement

2,438

25,500

Carrying Amount [Member]

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable

4,449,734

3,102,485

Mezzanine notes payable

311,040

Unsecured Senior Notes

5,835,854

4,639,528

Unsecured exchangeable senior notes

^[1]

744,880

1,170,356

Total

11,341,508

8,912,369

Estimated Fair Value [Member]

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable

4,545,283

3,256,940

Mezzanine notes payable

311,064

Unsecured Senior Notes

6,050,517

5,162,486

Unsecured exchangeable senior notes

750,266

1,278,554

Total

11,657,130

9,697,980

ASC 470-20 Adjustment [Member]

Summary Of Significant Accounting Policies [Line Items]

Impact of accounting pronouncement

$ 2,400

$ 25,500

[1]	Includes the net adjustment for the equity component allocation totaling approximately $2.4 million and $25.5 million at December 31, 2013 and December 31, 2012, respectively.

Summary Of Significant Accounting Policies Schedule Of Future Contractual Minimum Lease Payments Under Non-Cancelable Ground Leases (Details) $ in Thousands	Dec. 31, 2013 USD ($)
Summary of Significant Accounting Policies [Abstract]
2014	$ 13,184
2015	13,507
2016	13,732
2017	13,963
2018	14,198
Thereafter	$ 899,187

Summary Of Significant Accounting Policies GAAP Reconciliation Of Net Income To Taxable Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliaton of GAAP to taxable income [Abstract]
Net income attributable to Boston Properties Limited Partnership	$ 101,264	$ 174,140	$ 505,189	$ 60,923	$ 75,264	$ 66,234	$ 136,561	$ 56,542	$ 841,516	$ 334,601	$ 317,152
Straight line rent adjustments									(82,904)	(89,982)	(87,773)
Book/tax differences from depreciation and amortization									(174,384)	(106,862)	(118,728)
Book/tax differences on gains/losses from capital transactions									(138,300)	(24,958)	(45,056)
Book/tax differences from stock-based compensation									(46,935)	(22,035)	(937)
Other book/tax differences, net									(7,835)	(42,004)	(50,022)
Taxable Income									$ 849,466	$ 390,562	$ 354,010

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Net Income
-URI http://asc.fasb.org/extlink&oid=6518256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.19)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.18)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.22)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Other Comprehensive Income
-URI http://asc.fasb.org/extlink&oid=6519514

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e565-108580

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 19
-Article 5

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 20
-Article 9

+ Details

Summary Of Significant Accounting Policies Schedule of Finite Lived Intangible Assets Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2013 USD ($)
Finite-Lived Intangible Assets [Line Items]
2014	$ 91,903
2015	66,716
2016	55,083
2017	41,106
2018	36,306
Acquired Above-Market Lease Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
2014	23,669
2015	22,758
2016	20,576
2017	12,279
2018	8,637
Acquired Below-Market Lease Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
2014	61,700
2015	55,207
2016	52,461
2017	40,346
2018	$ 37,774

Real Estate (Narrative) (Details) $ in Thousands												3 Months Ended								7 Months Ended	9 Months Ended	12 Months Ended
Real Estate (Narrative) (Details) $ in Thousands	Dec. 20, 2013 USD ($) ft² Buildings	Aug. 22, 2013 USD ($) ft²	May 31, 2013 USD ($) ft² partners	Apr. 10, 2013 USD ($) ft² Buildings	Mar. 29, 2013 USD ($) ft²	Mar. 26, 2013 USD ($) ft² floor	Feb. 26, 2013	Feb. 20, 2013 USD ($)	Feb. 20, 2013 USD ($)	Feb. 07, 2013	Feb. 06, 2013 USD ($) ft² floor	Dec. 31, 2013 USD ($) ft² apartments	Sep. 30, 2013 USD ($)	Jun. 30, 2013 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Sep. 30, 2012 USD ($)	Jun. 30, 2012 USD ($)	Mar. 31, 2012 USD ($)	Dec. 31, 2013 USD ($) ft² apartments	Dec. 31, 2013 USD ($) ft² apartments	Dec. 31, 2013 USD ($) ft² apartments	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Oct. 29, 2013 ft²	Oct. 09, 2013 USD ($) ft²	Jun. 28, 2013 USD ($) ft²	Jun. 14, 2013 ft²	Apr. 25, 2013 ft²	Mar. 22, 2013 ft²
Real Estate Properties [Line Items]
Gain on consolidation of joint ventures																						$ 385,991	$ 0	$ 0
Payments to Acquire and Develop Real Estate																						522,900	788,052	112,180
Impairment loss from discontinued operations																						2,852	0	0
Revenue contributed by acquisitions												$ 576,199	$ 571,481	$ 510,033	$ 477,826	$ 478,047	$ 464,220	$ 466,197	$ 438,722			2,135,539	1,847,186	1,722,792
Earnings																						690,073	648,504	613,389
Gain on forgiveness of debt from discontinued operations																						20,736	0	0
Proceeds from the sale of real estate																						250,078	61,963	0
Gain on sale of real estate from discontinued operations																						115,459	38,445	0
Impairment loss																						$ 4,401	$ 0	$ 0
535 Mission [Member]
Real Estate Properties [Line Items]
Payments to Acquire and Develop Real Estate											$ 71,000
Net Rentable Area \| ft²											307,000
Number of floors in building \| floor											27
Transbay Tower [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²						1,400,000
Payments to Acquire Land						$ 192,000
Ownership Percentage							95.00%
Number of floors in building \| floor						60
Partners Joint Venture Ownership Percentage							5.00%			50.00%
Two Patriots Park [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																														256,000
Reston Signature Site [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²					250,000
Payments to Acquire Land					$ 27,000
601 Massachusetts Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																													478,000
Seventeen Cambridge Center [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																												195,000
The Avant at Reston Town Center Residential [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²												355,000								355,000	355,000	355,000
Property placed in-service (percentage)												63.00%								63.00%	63.00%	63.00%
Number of apartment units \| apartments												359								359	359	359
Plaza at Almaden [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																											840,000
Impairment loss															4,400
250 West 55th Street [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²												989,000								989,000	989,000	989,000
Property placed in-service (percentage)												6.00%								6.00%	6.00%	6.00%
680 Folsom Street [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²												525,000								525,000	525,000	525,000
Property placed in-service (percentage)												1.00%								1.00%	1.00%	1.00%
Mountain View Research And Technology Parks [Member]
Real Estate Properties [Line Items]
Gain on consolidation of joint ventures				$ 26,500
Aggregate purchase price				$ 233,084
Revenue contributed by acquisitions																					$ 16,700
Earnings																					$ 400
Mountain View Research [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²				604,000
Number of real estate properties \| Buildings				16
Mountain View Technology [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²				135,000
Number of real estate properties \| Buildings				7
767 5th Avenue (The General Motors Building) [Member]
Real Estate Properties [Line Items]
Gain on consolidation of joint ventures			$ 359,500
Net Rentable Area \| ft²			1,800,000
Revenue contributed by acquisitions																				$ 168,400
Earnings																				$ 8,400
Partners Joint Venture Ownership Percentage			40.00%
Montvale Center [Member]
Real Estate Properties [Line Items]
Amount of debt extinguished									$ 25,000
Gain on forgiveness of debt from discontinued operations								$ 20,700
303 Almaden [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																											158,000
Impairment loss from discontinued operations															$ 2,900
Contractual Sales Price																											$ 40,000
1301 New York Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²		201,000
Contractual Sales Price		$ 135,000
Proceeds from the sale of real estate		121,500
Gain on sale of real estate from discontinued operations		88,600
Net Contractual Sales Price		$ 121,700
Time Square Tower [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																										1,246,000
ownership interest sold (percent)																										45.00%
Proceeds from sale of an interest in a real estate asset																										$ 673,100
Net Contractual Sales Price																										684,000
Portion allocation to noncontrolling interest based on carrying value of the total equity of the property prior to the sale																										243,500
Difference between net cash proceeds received and noncontrolling interest recognized																										$ 429,600
10 and 20 Burlington Mall Road [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²	152,000
Contractual Sales Price	$ 30,000
Proceeds from the sale of real estate	29,400
Gain on sale of real estate from discontinued operations	$ 21,000
Number of real estate properties \| Buildings	2
One Preserve Parkway [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²	184,000
Contractual Sales Price	$ 61,300
Proceeds from the sale of real estate	59,900
Gain on sale of real estate from discontinued operations	$ 5,900
Cambridge Center Connector [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²												43,000								43,000	43,000	43,000
Princeton Build to Suit [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																									130,000
767 5th Avenue (The General Motors Building) [Member]
Real Estate Properties [Line Items]
Gain on consolidation of joint ventures			$ 359,500
Number of Joint Venture Partners \| partners			2

Real Estate Schedule of Real Estate Properties (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Real Estate [Abstract]
Land	$ 4,342,951	$ 2,496,547
Land held for future development	297,376	271,189
Buildings and improvements	10,742,370	9,191,497
Tenant improvements	1,617,401	1,435,508
Furniture, fixtures and equipment	25,164	23,441
Construction in progress	1,523,179	1,036,780
Total	18,548,441	14,454,962
Less: accumulated depreciation	(3,096,910)	(2,876,983)
Total real estate	$ 15,451,531	$ 11,577,979

Real Estate (Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition) (Details) - USD ($)
$ in Thousands

12 Months Ended

May 31, 2013

Apr. 10, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Restructuring Cost and Reserve [Line Items]

real estate and related intangibles recorded upon consolidation

$ 3,356,000

$ 0

Mortgage notes payable

4,449,734

3,102,485

Mezzanine notes payable

311,040

Outside members' notes payable

180,000

Debt recorded upon consolidation

2,056,000

Cash and cash equivalents

79,468

Accrued interest payable

167,523

72,461

Working capital recorded upon consolidation

177,315

Noncontrolling Interests recorded upon consolidation

$ 480,861

$ 0

767 5th Avenue (The General Motors Building) [Member]

Restructuring Cost and Reserve [Line Items]

Land

$ 1,796,252

Building and improvements

1,447,446

Tenant Improvements

85,208

In-place lease intangibles

357,781

Above market rents

101,897

Below market rents

239,641

Above Market Assumed Debt Adjustments

192,943

real estate and related intangibles recorded upon consolidation

3,356,000

Mortgage notes payable

1,300,000

Mezzanine notes payable

306,000

Outside members' notes payable

^[1]

450,000

Debt recorded upon consolidation

2,056,000

Cash and cash equivalents

79,468

Cash held in escrows

2,403

Tenant and other receivables

7,104

Prepaid expense and other assets

4,269

Accounts payable and accrued expenses

2,418

Accrued interest payable

^[2]

182,369

Other Liabilities

6,304

Working capital recorded upon consolidation

97,847

Noncontrolling Interest

520,000

Noncontrolling interest - working capital

39,139

Noncontrolling Interests recorded upon consolidation

480,861

Net Assets Recorded Upon Consolidation

721,292

Mountain View Research And Technology Parks [Member]

Restructuring Cost and Reserve [Line Items]

Land

$ 126,521

Building and improvements

82,451

Tenant Improvements

7,326

In-place lease intangibles

23,279

Above market rents

843

Below market rents

7,336

Aggregate purchase price

$ 233,084

Consolidation, Eliminations [Member] | 767 5th Avenue (The General Motors Building) [Member]

Restructuring Cost and Reserve [Line Items]

Outside members' notes payable

270,000

Accrued interest payable

$ 105,500

[1]	The Company's member loan totaling $270.0 million eliminates in consolidation.
[2]	The Company's share of the accrued interest payable on the members' loans totaling approximately $105.5 million eliminates in consolidation.

Real Estate (Pro Forma In Connection With Acquisition) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Real Estate [Abstract]
Total revenue	$ 2,257,098	$ 2,149,391
Income from continuing operations	314,307	642,640
Net income attributable to Boston Properties Limited Partnership	$ 452,813	$ 710,690
Basic earnings per unit: Net income per unit attributable to Boston Properties Limited Partnership (in dollars per unit)	$ 2.68	$ 4.21
Diluted earnings per unit: Net income per unit attributable to Boston Properties Limited Partnership (in dollars per unit)	$ 2.67	$ 4.20

Real Estate (Summary Of The Discontinued Operations Related To Bedford Business Park) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue	$ 576,199	$ 571,481	$ 510,033	$ 477,826	$ 478,047	$ 464,220	$ 466,197	$ 438,722	$ 2,135,539	$ 1,847,186	$ 1,722,792
Expenses
Depreciation and amortization									552,589	437,692	421,519
Total expenses									1,445,466	1,198,682	1,109,403
Operating Income (Loss)									690,073	648,504	613,389
Other Expenses
Interest expense									446,880	410,970	391,533
Income from discontinued operations attributable to Boston Properties Limited Partnership									141,365	48,251	10,876
Gain on sale of real estate from discontinued operations attributable to Boston Properties Limited Partnership									115,459	38,445	0
Gain on forgiveness of debt from discontinued operations									20,736	0	0
Impairment loss from discontinued operations									(2,852)	0	0
10 & 20 Burlington Mall Road, One Preserve Parkway, 1301 New York Avenue, 303 Almaden Blvd, Montvale Center and Bedford Business Park [Member] [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue									20,138	32,607	36,734
Expenses
Operating									6,996	12,038	13,818
Depreciation and amortization									4,760	8,169	9,442
Total expenses									11,756	20,207	23,260
Operating Income (Loss)									8,382	12,400	13,474
Other Expenses
Interest expense									360	2,594	2,598
Income from discontinued operations attributable to Boston Properties Limited Partnership									8,022	9,806	10,876
Gain on sale of real estate from discontinued operations attributable to Boston Properties Limited Partnership									115,459	38,445	0
Gain on forgiveness of debt from discontinued operations									20,736	0	0
Impairment loss from discontinued operations									$ (2,852)	$ 0	$ 0

Deferred Charges (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Deferred Charges [Abstract]
Leasing costs, including lease related intangibles	$ 1,183,204	$ 790,740
Financing costs	76,798	90,682
Deferred charges gross	1,260,002	881,422
Less: Accumulated amortization	375,552	293,187
Deferred charges, total	$ 884,450	$ 588,235

Deferred Charges Schedule of Acquired In-Place Lease Intangibles (Details) $ in Thousands	Dec. 31, 2013 USD ($)
Deferred Charges [Abstract]
2014	$ 91,903
2015	66,716
2016	55,083
2017	41,106
2018	$ 36,306

Investments in Unconsolidated Joint Ventures (Investments in Unconsolidated Joint Ventures) (Details)

12 Months Ended

Dec. 31, 2013

Land_Parcels

Buildings

Square 407 Limited Partnership [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Market Square North

Equity Method Investment, Ownership Percentage

50.00%

The Metropolitan Square Associates LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Metropolitan Square

Equity Method Investment, Ownership Percentage

51.00%

BP/CRF 901 New York Avenue LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

901 New York Avenue

^[1]

Equity Method Investment, Ownership Percentage

25.00%

^[1]

WP Project Developer LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Wisconsin Place Land and Infrastructure

^[2]

Equity Method Investment, Ownership Percentage

33.30%

^[2]

RBP Joint Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

N/A

^[3]

Equity Method Investment, Ownership Percentage

50.00%

^[3]

Boston Properties Office Value-Added Fund, L.P. [Member]

Schedule of Equity Method Investments [Line Items]

Properties

N/A

^[4]

Equity Method Investment, Ownership Percentage

39.50%

^[4]

Annapolis Junction NFM, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Annapolis Junction

^[5]

Equity Method Investment, Ownership Percentage

50.00%

^[5]

Number of real estate properties

Number of buildings under construction

Parcels of undeveloped land | Land_Parcels

2 GCT Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

N/A

^[6]

Equity Method Investment, Ownership Percentage

60.00%

^[6]

540 Madison Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

540 Madison Avenue

Equity Method Investment, Ownership Percentage

60.00%

125 West 55th Street Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

N/A

^[7]

Equity Method Investment, Ownership Percentage

60.00%

^[7]

500 North Capitol LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

500 North Capitol Street, NW

Equity Method Investment, Ownership Percentage

30.00%

Entity Owning Land And Infrastructure Of Project [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

33.30%

[1]	The Company’s economic ownership can increase based on the achievement of certain return thresholds.
[2]	The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land, parking and infrastructure of the project.
[3]	Eighth Avenue and 46th Street was sold on July 19, 2013.
[4]	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of December 31, 2013, the investment is comprised of undistributed cash.
[5]	Comprised of two buildings, one building under construction and two undeveloped land parcels.
[6]	Two Grand Central Tower was sold on October 25, 2011. As of December 31, 2013, the investment is comprised of undistributed cash.
[7]	125 West 55th Street was sold on May 30, 2013. As of December 31, 2013, the investment is comprised of undistributed cash.

Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($)
$ in Thousands

Dec. 31, 2013

Dec. 31, 2012

ASSETS

Real estate and development in process, net

$ 15,451,531

$ 11,577,979

LIABILITIES AND MEMBERS'/PARTNERS' EQUITY

Other liabilities

578,969

324,613

Total liabilities and capital

19,796,588

15,081,132

Carrying value of the Company's investments in unconsolidated joint ventures

126,084

659,916

Unconsolidated Joint Ventures [Member]

ASSETS

Real estate and development in process, net

924,297

4,494,971

Other assets

163,149

673,716

Total assets

1,087,446

5,168,687

LIABILITIES AND MEMBERS'/PARTNERS' EQUITY

Other liabilities

28,830

792,888

Members'/Partners' equity

308,884

1,335,877

Total liabilities and capital

1,087,446

5,168,687

Company's share of equity

154,726

787,941

Basis differentials

^[1]

(28,642)

(128,025)

Carrying value of the Company's investments in unconsolidated joint ventures

$ 126,084

$ 659,916

[1]

Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Schedule of Equity Method Investments [Line Items]

Total revenue

$ 576,199

$ 571,481

$ 510,033

$ 477,826

$ 478,047

$ 464,220

$ 466,197

$ 438,722

$ 2,135,539

$ 1,847,186

$ 1,722,792

Expenses

Depreciation and amortization

552,589

437,692

421,519

Total expenses

1,445,466

1,198,682

1,109,403

Operating Income (Loss)

690,073

648,504

613,389

Other income (expense)

Interest expense

446,880

410,970

391,533

Losses from early extinguishments of debt

122

(4,453)

(1,494)

Income (Loss) from Continuing Operations

715,601

293,639

311,173

Net Income (Loss)

856,966

341,890

322,049

Income from unconsolidated joint ventures

75,074

49,078

85,896

Straight-line rent adjustments

65,800

77,600

77,000

Below market rent adjustments, net

28,000

14,600

10,800

Gain on consolidation of joint ventures

385,991

Unconsolidated Joint Ventures [Member]

Schedule of Equity Method Investments [Line Items]

Total revenue

^[1]

311,548

564,205

589,294

Expenses

Operating

105,319

162,665

170,404

Depreciation and amortization

86,088

163,134

190,437

Impairment losses

40,468

Total expenses

191,407

325,799

401,309

Operating Income (Loss)

120,141

238,406

187,985

Other income (expense)

Interest expense

112,535

224,645

228,494

Losses from early extinguishments of debt

(1,677)

Income (Loss) from Continuing Operations

5,929

13,761

(40,509)

Gain on sale of real estate

14,207

990

Net Income (Loss)

20,136

14,751

(40,509)

Company's share of net income (loss)

4,612

6,863

(25,374)

Gains on sale of real estate

54,501

46,166

Basis differential

(1,017)

1,732

27,226

Elimination of inter-entity interest on partner loan

16,978

40,483

37,878

Income from unconsolidated joint ventures

75,074

49,078

85,896

Straight-line rent adjustments

7,800

12,000

21,900

Below market rent adjustments, net

33,700

91,100

120,300

Lease termination income

19,600

Company share of lease termination income

11,800

Gain on consolidation of joint ventures

$ 385,991

$ 0

[1]

Investments in Unconsolidated Joint Ventures Investment in Unconsolidated Joint Ventures (Narrative) (Details) $ in Thousands								12 Months Ended
	Oct. 29, 2013 USD ($) ft²	Jul. 19, 2013 USD ($)	Jun. 05, 2013 USD ($)	May 31, 2013 USD ($) partners	May 30, 2013 USD ($) ft²	Apr. 10, 2013 USD ($)	Apr. 04, 2013 USD ($) yr	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Sep. 26, 2013 ft²	Mar. 31, 2013 ft²	Feb. 28, 2013 ft²
Schedule of Equity Method Investments [Line Items]
Repayments of Secured Debt								$ 80,311	$ 253,877	$ 1,251,841
Coupon/Stated Rate (percent)								3.625%
Maturity date								Feb. 15, 2014
Gains (losses) from early extinguishments of debt								$ 122	(4,453)	(1,494)
Proceeds from mortgage notes payable								0	0	1,178,306
Gain on consolidation of joint ventures								$ 385,991	$ 0	$ 0
125 West 55th Street [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage					60.00%
Net Rentable Area \| ft²					588,000
Contractual Sales Price					$ 470,000
Carrying Value of Debt Assumed in Sale					$ 198,600
Coupon/Stated Rate (percent)					6.09%
Cash Proceeds from the Sale of Real Estate Property					$ 253,700
Gain on sale of real estate					$ 43,200
Maturity date					Mar. 10, 2020
767 5th Avenue (The General Motors Building) [Member]
Schedule of Equity Method Investments [Line Items]
Number of Joint Venture Partners \| partners				2
Gain on consolidation of joint ventures				$ 359,500
Mountain View Research And Technology Parks [Member]
Schedule of Equity Method Investments [Line Items]
Gains (losses) from early extinguishments of debt						$ (400)
Gain on consolidation of joint ventures						$ 26,500
Mountain View Research [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis						LIBOR plus 2.00%
Repayments of Secured Debt						$ 90,000
Debt Instrument, Basis Spread on Variable Rate						2.00%
Maturity date						May 31, 2014
Repayments of Notes Payable						$ 8,600
Mountain View Technology [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis						LIBOR plus 2.50%
Repayments of Secured Debt						$ 20,000
Debt Instrument, Basis Spread on Variable Rate						2.50%
Maturity date						Nov. 22, 2014
Repayments of Notes Payable						$ 3,700
Annapolis Junction Building Six [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis	LIBOR plus 1.65%
Equity Method Investment, Ownership Percentage	50.00%												50.00%
Net Rentable Area \| ft²	119,000												119,000
Debt Instrument, Basis Spread on Variable Rate	1.65%
Maturity date	Nov. 17, 2014
Construction Loan	$ 14,000
500 North Capitol [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage				30.00%								30.00%
Net Rentable Area \| ft²												231,000
Annapolis Junction Building Seven [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage							50.00%				50.00%
Net Rentable Area \| ft²											125,000
Construction Loan Facility Borrowing Capacity							$ 22,000
Debt Instrument, Basis Spread on Variable Rate							1.65%
Maturity date							Apr. 04, 2016
Number of extensions							2
Extension Option (in years) \| yr							1
540 Madison Avenue [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			60.00%
Eighth Avenue and Forty Sixth Street [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Imputed Sales Price		$ 45,000
Cash Proceeds from the Sale of Real Estate Property		21,800
Gain on sale of real estate		12,600
Company [Member] \| 125 West 55th Street [Member]
Schedule of Equity Method Investments [Line Items]
Cash Proceeds from the Sale of Real Estate Property					$ 152,200
Company [Member] \| Mountain View Research And Technology Parks [Member]
Schedule of Equity Method Investments [Line Items]
Gains (losses) from early extinguishments of debt						$ (200)
Company [Member] \| Eighth Avenue and Forty Sixth Street [Member]
Schedule of Equity Method Investments [Line Items]
Gain on sale of real estate		$ 11,300
Construction Loans [Member] \| 500 North Capitol [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis				LIBOR plus 1.65%
Repayments of Secured Debt				$ 90,600
Debt Instrument, Basis Spread on Variable Rate				1.65%
Maturity date				Oct. 14, 2014
Gains (losses) from early extinguishments of debt				$ (1,000)
Construction Loans [Member] \| Company [Member] \| 500 North Capitol [Member]
Schedule of Equity Method Investments [Line Items]
Gains (losses) from early extinguishments of debt				$ (300)
First Mortgage [Member] \| 500 North Capitol [Member]
Schedule of Equity Method Investments [Line Items]
Coupon/Stated Rate (percent)				4.15%
Maturity date				Jun. 06, 2023
Proceeds from mortgage notes payable				$ 105,000
First Mortgage [Member] \| 540 Madison Avenue [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis			LIBOR plus 1.50%
Debt Instrument, Basis Spread on Variable Rate			1.50%
Maturity date			Jun. 05, 2018
Proceeds from mortgage notes payable			$ 120,000
Prior to refinance first mortgage loan [Member] \| 540 Madison Avenue [Member]
Schedule of Equity Method Investments [Line Items]
Repayments of Secured Debt			$ 118,000
Coupon/Stated Rate (percent)			5.20%
Maturity date			Jul. 11, 2013
Gains (losses) from early extinguishments of debt			$ (300)
Prior to refinance first mortgage loan [Member] \| Company [Member] \| 540 Madison Avenue [Member]
Schedule of Equity Method Investments [Line Items]
Gains (losses) from early extinguishments of debt			$ (200)
Prior to extension [Member] \| Annapolis Junction Building Six [Member]
Schedule of Equity Method Investments [Line Items]
Maturity date	Nov. 17, 2013
Mountain View Research And Technology Parks [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage						39.50%
Ownership upon acquisition						100.00%

Mortgage Notes Payable Schedule Of Aggregate Principal Payments On Mortgage Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2013	Dec. 31, 2012
Mortgage Notes Payable [Abstract]
2014	$ 87,759
2015	26,182
2016	608,879
2017	2,821,750
2018	18,633
Thereafter	695,327
Total	4,258,530
Unamoritzed balance of histroical fair value adjustments	191,204
Total carrying value of mortgage notes payable	$ 4,449,734	$ 3,102,485

Mortgage Notes Payable (Narrative) (Details) - USD ($)					7 Months Ended	12 Months Ended
Mortgage Notes Payable (Narrative) (Details) - USD ($)	May 31, 2013	Feb. 20, 2013	Feb. 20, 2013	Feb. 05, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Mortgage Notes Payable [Line Items]
Mortgage notes payable					$ 4,449,734,000	$ 4,449,734,000	$ 3,102,485,000
Final maturity date of mortgage notes						Apr. 10, 2022
Maturity date						Feb. 15, 2014
Outside members' notes payable					$ 180,000,000	$ 180,000,000	0
Gain on forgiveness of debt from discontinued operations						20,736,000	0	$ 0
Repayments of mortgage notes payable						$ 80,311,000	253,877,000	1,251,841,000
Interest at a fixed rate (percent)					3.625%	3.625%
Gains (losses) from early extinguishments of debt						$ 122,000	$ (4,453,000)	(1,494,000)
Number Of Mortgage Loans Accounted For Fair Value					4	4	5
Outstanding balance of mortgage loans accounted for at fair value					$ 2,200,000,000	$ 2,200,000,000	$ 951,500,000
nterest Expense Decrease Due To Recording Mortgage Loans At Fair Value						34,400,000	7,000,000	$ 9,200,000
Cumulative Liability Related to the Fair Value of Debt Adjustment					191,200,000	191,200,000	38,600,000
Interest Payable					$ 167,523,000	$ 167,523,000	72,461,000
Kingstowne One [Member]
Mortgage Notes Payable [Line Items]
Maturity date				May 05, 2013
Repayments of mortgage notes payable				$ 17,000,000
Interest at a fixed rate (percent)				5.96%
Penalty for early repayment of debt				$ 0.0
140 Kendrick [Member]
Mortgage Notes Payable [Line Items]
Maturity date						Jul. 01, 2013
Repayments of mortgage notes payable						$ 47,600,000
Interest at a fixed rate (percent)					7.51%	7.51%
Penalty for early repayment of debt						$ 0
Gains (losses) from early extinguishments of debt						300,000
767 5th Avenue (The General Motors Building) [Member]
Mortgage Notes Payable [Line Items]
Maturity date	Jun. 09, 2017
Outside members' notes payable	$ 450,000,000
Interest at a fixed rate (percent)	11.00%
Interest Payable	$ 175,800,000
Interest Expense, Related Party					$ 16,000,000
Montvale Center [Member]
Mortgage Notes Payable [Line Items]
Amount of debt extinguished			$ 25,000,000
Gain on forgiveness of debt from discontinued operations		$ 20,700,000
Fixed Rate Mortgages [Member]
Mortgage Notes Payable [Line Items]
Mortgage notes payable					$ 4,400,000,000	$ 4,400,000,000	$ 3,100,000,000
Contractual interest rate range, minimum						4.75%	4.75%
Contractual interest rate range, maximum						7.69%	9.93%
Contractual interest rate weighted average interest rate					5.70%	5.70%	5.65%
Variable Rate Mortgages [Member]
Mortgage Notes Payable [Line Items]
Number of variable rate mortgage loans					0	0	0
London Interbank Offered Rate					0.17%	0.17%	0.21%
Minimum [Member]
Mortgage Notes Payable [Line Items]
Number Real Estate Assets Used For Mortgage Loan Collateral						1	1
Mezzanine Debt [Member] \| 767 5th Avenue (The General Motors Building) [Member]
Mortgage Notes Payable [Line Items]
Maturity date	Oct. 07, 2017
Interest at a fixed rate (percent)	6.02%
Debt recorded upon consolidation	$ 306,000,000
Mortgage Loans Accounted For At Fair Value Upon Consolidation	$ 311,700,000
Interest Rate Used To Account For Mortgage Loan At Fai rValue Upon Consolidation	5.53%
First Mortgage [Member] \| 767 5th Avenue (The General Motors Building) [Member]
Mortgage Notes Payable [Line Items]
Maturity date	Oct. 07, 2017
Interest at a fixed rate (percent)	5.95%
Debt recorded upon consolidation	$ 1,300,000,000
Mortgage Loans Accounted For At Fair Value Upon Consolidation	$ 1,500,000,000
Interest Rate Used To Account For Mortgage Loan At Fai rValue Upon Consolidation	2.44%
Company [Member] \| 767 5th Avenue (The General Motors Building) [Member]
Mortgage Notes Payable [Line Items]
Outside members' notes payable					$ 180,000,000	$ 180,000,000
Interest Payable					76,400,000	76,400,000
Consolidation, Eliminations [Member] \| 767 5th Avenue (The General Motors Building) [Member]
Mortgage Notes Payable [Line Items]
Outside members' notes payable					270,000,000	270,000,000
Interest Payable					$ 114,500,000	$ 114,500,000

Unsecured Senior Notes Schedule of Unsecured Senior Notes (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

3.625%

Effective Rate (percent)

^[1]

4.037%

Principal Amount

$ 747,500

Maturity date

Feb. 15, 2014

Net unamortized discount

$ (14,146)

$ (10,472)

Total

5,835,854

$ 4,639,528

Senior Notes [Member]

Debt Instrument [Line Items]

Principal Amount

5,850,000

Net unamortized discount

(14,146)

Total

$ 5,835,854

Senior Notes [Member] | Twelve Year Unsecured Senior Notes Five Point Six Nine Three Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

5.625%

Effective Rate (percent)

^[2]

5.693%

Principal Amount

$ 300,000

Maturity date

^[3]

Apr. 15, 2015

Senior Notes [Member] | Twelve Year Unsecured Senior Notes Five Point One Nine Four Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

5.00%

Effective Rate (percent)

^[2]

5.194%

Principal Amount

$ 250,000

Maturity date

^[3]

Jun. 01, 2015

Senior Notes [Member] | Ten Year Unsecured Senior Notes Five Point Nine Six Seven Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

5.875%

Effective Rate (percent)

^[2]

5.967%

Principal Amount

$ 700,000

Maturity date

^[3]

Oct. 15, 2019

Senior Notes [Member] | Ten Year Unsecured Senior Notes Five Point Seven Zero Eight Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

5.625%

Effective Rate (percent)

^[2]

5.708%

Principal Amount

$ 700,000

Maturity date

^[3]

Nov. 15, 2020

Senior Notes [Member] | Ten Year Unsecured Senior Notes Four Point Two Eight Nine Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

4.125%

Effective Rate (percent)

^[2]

4.289%

Principal Amount

$ 850,000

Maturity date

^[3]

May 15, 2021

Senior Notes [Member] | Seven Year Unsecured Senior Notes Three Point Eight Five Three Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

3.70%

Effective Rate (percent)

^[2]

3.853%

Principal Amount

$ 850,000

Maturity date

^[3]

Nov. 15, 2018

Senior Notes [Member] | Eleven Year Unsecured Senior Notes Three Point Nine Five Four Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

3.85%

Effective Rate (percent)

^[2]

3.954%

Principal Amount

$ 1,000,000

Maturity date

^[3]

Feb. 01, 2023

Senior Notes [Member] | Ten and Half Year Unsecured Senior Notes Three Point Two Seven Nine Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

3.125%

Effective Rate (percent)

^[2]

3.279%

Principal Amount

$ 500,000

Maturity date

^[3]

Sep. 01, 2023

Senior Notes [Member] | Ten and Half Year Unsecured Senior Notes Three Point Nine One Six Percent [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate (percent)

3.80%

Effective Rate (percent)

^[2]

3.916%

Principal Amount

$ 700,000

Maturity date

^[3]

Feb. 01, 2024

[1]	Yield on issuance date including the effects of discounts on the notes but excluding the effects of the adjustment for the equity component allocation.
[2]	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.
[3]	No principal amounts are due prior to maturity.

Unsecured Senior Notes Unsecured Senior Notes (Narrative) (Details) - USD ($)
$ in Thousands

12 Months Ended

Jun. 27, 2013

Apr. 11, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Debt Instrument [Line Items]

Proceeds from unsecured senior notes

$ 1,194,753

$ 997,790

$ 848,019

Maximum Secured Debt Leverage Ratio

55.00%

Coupon/Stated Rate (percent)

3.625%

Effective Rate (percent)

^[1]

4.037%

Maturity date

Feb. 15, 2014

Three Point Two Seven Nine Percent Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Senior Notes price (as a percent of principal amount)

99.379%

Proceeds from unsecured senior notes

$ 492,500

Debt Instrument, Face Amount

$ 500,000

Coupon/Stated Rate (percent)

3.125%

Effective Rate (percent)

3.279%

Maturity date

Sep. 01, 2023

Three Point Nine One Six Percent Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Senior Notes price (as a percent of principal amount)

99.694%

Proceeds from unsecured senior notes

$ 691,900

Debt Instrument, Face Amount

$ 700,000

Coupon/Stated Rate (percent)

3.80%

Effective Rate (percent)

3.916%

Maturity date

Feb. 01, 2024

Senior Notes [Member]

Debt Instrument [Line Items]

Maximum Leverage Ratio

60.00%

Maximum Secured Debt Leverage Ratio

50.00%

Minimum Interest Coverage Ratio

1.50

Minimum Unencumbered Asset Value Percentage Of Unsecured Debt

150.00%

[1]	Yield on issuance date including the effects of discounts on the notes but excluding the effects of the adjustment for the equity component allocation.

Unsecured Exchangeable Senior Notes (Schedule of Unsecured Exchangeable Senior Notes) (Details)

12 Months Ended

Dec. 31, 2013

USD ($)

$ / shares

Dec. 31, 2012

USD ($)

Aug. 19, 2008

USD ($)

$ / shares

Aug. 13, 2008

$ / shares

Debt Disclosure [Abstract]

Coupon/Stated Rate (percent)

3.625%

Effective Rate (percent)

^[1]

4.037%

Exchange Rate (in shares)

^[2]

8.6974

Principal Amount

$ 747,500,000

Net unamortized discount

(182,000)

$ (1,653,000)

Adjustment for the equity component allocation, net of accumulated amortization

(2,438,000)

(25,500,000)

Total

$ 744,880,000

$ 1,170,356,000

Maturity date

Feb. 15, 2014

Initial exchange rate (in shares) | shares

8.5051

Initial exchange on principal amount of note

$ 1,000

Initial exchange price (in dollars per share) | $ / shares

$ 117.58

Revised exchange price due to capped call transaction (in dollars per share) | $ / shares

$ 137.17

Premium over closing price (percent)

40.00%

Closing price per share of common stock (in dollars per share) | $ / shares

$ 97.98

Net cost of capped call transaction

$ 44,400,000

Effective exchange price (in dollars per share) | $ / shares

$ 130.21

Revised exchange price due to special dividend | $ / shares

$ 114.98

Revised exchange rate | shares

8.6974

[1]

Yield on issuance date including the effects of discounts on the notes but excluding the effects of the adjustment for the equity component allocation.

[2]

Unsecured Exchangeable Senior Notes (Narrative) (Details) - USD ($)		12 Months Ended
	May 18, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Debt Instrument, Convertible, Carrying Amount of Equity Component		$ 91,900,000	$ 148,500,000
Debt Instrument Convertible Initial Carrying Amount Of The Equity Component		230,300,000
Deferred Financing Costs Equity Component		$ 1,000,000
Coupon/Stated Rate (percent)		3.625%
Amount paid for repurchase		$ 0	224,261,000	$ 0
Convertible Notes Payable		744,880,000	1,170,356,000
Net Of Adjustment For Equity Component Allocation		2,438,000	25,500,000
Debt Instrument, Convertible, Interest Expense		34,800,000	48,400,000	66,300,000
Interest Expense Adjustment Related To Convertible Debt		23,100,000	29,100,000	38,800,000
Gains (losses) from early extinguishments of debt		122,000	(4,453,000)	(1,494,000)
2.875% Exchangeable Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 862,500,000
Coupon/Stated Rate (percent)				2.875%
Convertible Debt Effective Interest Rate				5.63%
Three Point Seven Five Zero Percent Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 450,000,000
Coupon/Stated Rate (percent)			3.75%
Convertible Debt Effective Interest Rate			5.958%
3.625% Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 747,500,000
Coupon/Stated Rate (percent)		3.625%
Convertible Debt Effective Interest Rate		6.555%
Three Point Seven Five Zero Percent Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Coupon/Stated Rate (percent)	3.75%
Notes redemption date	May 18, 2013
Debt instrument redemption price percentage of principal (percent)	100.00%
Shares issued	419,116
Gains (losses) from early extinguishments of debt	$ (100,000)
Redeemed amount [Member] \| Three Point Seven Five Zero Percent Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Amount paid for repurchase	990,000
Submitted for Exchange [Member] \| Three Point Seven Five Zero Percent Exchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Amount paid for repurchase	$ 449,010,000

Unsecured Line of Credit (Details)		12 Months Ended
Unsecured Line of Credit (Details)	Jul. 26, 2013 USD ($) mo	Dec. 31, 2013 USD ($) yr	Dec. 31, 2012 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding		$ 0.0	$ 0
Leverage Ratio, Maximum		60.00%
Leverage Ratio Maximum Increasing Limit		65.00%
Leverage Ratio Reduction Limit		60.00%
Leverage Ratio Reduction Period, Years \| yr		1
Maximum Secured Debt Leverage Ratio		55.00%
Fixed Charge Coverage Ratio Minimum.		1.40
Maximum Unsecured Debt Leverage Ratio		60.00%
Unsecured Debt Leverage Ratio Reduction Limit		60.00%
Unsecured Debt Leverage Ratio Maximum Increasing Limit		65.00%
Unsecured Debt Leverage Ratio Reduction Period, Years \| yr		1
Unsecured Debt Interest Coverage Ratio Minimum.		1.75
Prior to Amendment [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 750,000,000
Line of Credit Facility, Expiration Date	Jun. 24, 2014
After the Amendment [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,000,000,000
Line of Credit Facility, Expiration Date	Jul. 26, 2018
Alternative Base Interest Rate Calculation [Member]
Line of Credit Facility [Line Items]
Amount added to Federal Funds Rate to Calculate Interest Rate	0.50%
LIBOR Period Used to Calculate Interest Rate (in months) \| mo	1
Amount added to LIBOR to Calculate Interest Rate	1.00%
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.35%
Maximum [Member] \| After the Amendment [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,500,000,000
Maximum [Member] \| Interest Rate Based on LIBOR or CDOR [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	1.70%
Maximum [Member] \| Alternative Base Interest Rate Calculation [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	0.70%
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.125%
Minimum [Member] \| Interest Rate Based on LIBOR or CDOR [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	0.925%
Minimum [Member] \| Alternative Base Interest Rate Calculation [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	0.00%
Rate Based on Current Credit Rating [Member] \| Interest Rate Based on LIBOR or CDOR [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate		1.00%
Rate Based on Current Credit Rating [Member] \| Alternative Base Interest Rate Calculation [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate		0.00%
Rate Based on Current Credit Rating [Member] \| Current Rates Based on Credit Ratings [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.15%

Commitments And Contingencies (Details) $ in Millions	3 Months Ended	12 Months Ended
Commitments And Contingencies (Details) $ in Millions	Mar. 31, 2014 USD ($)	Dec. 31, 2013 USD ($) Buildings
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations		$ 13.9
Maturity date		Feb. 15, 2014
Property insurance program per occurrence limits		$ 1,000.0
Per occurrence limit for NBCR Coverage		1,000.0
Value of program trigger		$ 100.0
Coinsurance of program trigger (percent)		15.00%
Deductible in insurance as a percentage of the value of the affected property, San Francisco (percent)	5.00%
Per occurrence limit of the earthquake insurance which covers San Francisco region	$ 120.0
Annual aggregate limit of the earthquake insurance which covers San Francisco region	120.0
Amount of earthquake insurance provided by IXP, LLC as direct insurer San Francisco	20.0
Earthquake Coverage Included In Builders Risk Policy For 535 Mission	15.0
Earthquake Coverage Included In Builders Risk Policy for below grade improvements for Transbay Tower	$ 15.0
Operating partnership guarantee to cover liabilities of IXP		$ 20.0
Contractual Tax Agreements Number Of Properties \| Buildings		3
Expiration of Tax Protection for 767 5th Avenue (the General Motors Building)		Jun. 09, 2017
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation		$ 24.1
Property insurance program per occurrence limits		1,625.0
Coverage for acts of Terrorism certified under TRIA in excess of amount provided by NYXP, LLC, as a direct insurer		1,375.0
Coverage for acts of terrorism certified under TRIA covered by NYXP		250.0
John Hancock Tower [Member]
Commitments And Contingencies [Line Items]
Guarantee Obligation Related To Tenant Re-Leasing Costs		$ 15.9
Maturity date		Jan. 06, 2017
601 Lexington Avenue [Member]
Commitments And Contingencies [Line Items]
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP		$ 250.0

Noncontrolling Interests (Narrative) (Details)	Dec. 31, 2013 shares
Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Operating Partnership (OP) Units (in shares)	15,583,370
Long-Term Incentive Plan (LTIP) Units (in shares)	1,455,761
Series Two Preferred Units (in shares)	666,116
Convertible Operating Partnership (OP) Units (in shares)	874,168
Series Four Preferred Units (in shares)	360,126
OPP Units 2011 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	396,500
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	396,150
MYLTIP 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	316,325

Noncontrolling Interests (Redeemable Preferred Units) (Narrative) (Details) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2014 $ / shares shares	Dec. 31, 2013 shares	Dec. 31, 2012 shares	Dec. 31, 2013 shareholder	Dec. 31, 2013 shares	Dec. 31, 2013 USD ($)	Dec. 31, 2013 $ / shares	Nov. 15, 2013 $ / shares	Aug. 29, 2013 d $ / shares shares	Aug. 15, 2013 $ / shares	May 15, 2013 $ / shares	Feb. 15, 2013 $ / shares	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Aug. 13, 2008 $ / shares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Closing price of common stock (in dollars per share)																$ 97.98
Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Series Two Preferred Units (in shares) \| shares					666,116
Series Four Preferred Units \| shares					360,126
Series Two Preferred Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for each Preferred Unit (in shares) \| shares	1.312336
Units converted (in shares) \| shares		329,881	117,047
Preferred Units Liquidation Preference	$ 50.00
Series Two Preferred Units [Member] \| Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Series Two Preferred Units (in shares) \| shares					666,116
Liquidation preference percentage		6.00%
Operating Units liquidation preference (in dollars per share)							$ 38.10
OP Units for each Preferred Unit (in shares) \| shares		1.312336
Number of holders exercising redemption rights		0	0	0									0	0	0
Distributions to Series Two Preferred Units (in dollars per share)								$ 0.85302		$ 0.85302	$ 0.85302	$ 0.85302
Preferred Units Liquidation Preference							50.00
Series Four Preferred Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Preferred Units Liquidation Preference	$ 50.00								$ 50.00
Series Four Preferred Units Annual Dividend Payable Rate	2.00%
Series Four Preferred Units Redeemed \| shares									861,400
Series Four Preferred Units [Member] \| Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distributions to Series Two Preferred Units (in dollars per share)								$ 0.25		$ 0.25	$ 0.25	$ 0.25
Preferred Units Liquidation Preference							50.00
First opportunity to redeem Series Four Preferred Units (in days) \| d									30
Series Four Preferred Units Annual Dividend Payable Rate		2.00%
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Units converted (in shares) \| shares		432,914	153,605
Value of Series Two Preferred Units assuming conversion \| $						$ 87.7
Closing price of common stock (in dollars per share)							$ 100.37
Redemption Year Two Thousand Fourteen [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dates Series Two Preferred holders can require Operating Partnership to redeem their units for cash		May 12, 2014

Noncontrolling Interests (Common Units) (Narrative) (Details) - USD ($) $ / shares in Units, $ in Billions					12 Months Ended
	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 29, 2013	Dec. 31, 2013	Dec. 31, 2012	Nov. 27, 2013	Aug. 13, 2008
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Closing price of common stock (in dollars per share)								$ 97.98
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares)					929,441	1,110,660
Redemption of OP units issued on conversion of Series Two Preferred Units (in shares)					432,914	153,605
Redemption of OP units issued on conversion of LTIP Units (in shares)					24,028	544,729
OPP Units and MYLTIP Units distribution prior to measurement date					10.00%
Distributions made to OP and LTIP units per unit (in dollars per share)	$ 0.65	$ 0.65	$ 0.65	$ 0.65
Distribution paid to OPP and MYLTIP Units (in dollars per share)	$ 0.065	$ 0.065	$ 0.065	$ 0.065
Common units of operating partnership if converted value					$ 1.7
Distributions Declared To OP And LTIP Units Per Unit							$ 0.65
Distributions Declared To Outperformance Awards Long Term Incentive Plan Units Per Unit							0.065
OPP Units 2011 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)					396,500
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)					396,150
MYLTIP 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)					316,325
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Closing price of common stock (in dollars per share)					$ 100.37
Quarter 4 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date					Jan. 29, 2013
Quarter 4 2012 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distribution Made to Limited Partner, Date of Record					Dec. 31, 2012
Dividend payable date					Jan. 29, 2013
Quarter 1 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date					Apr. 30, 2013
Quarter 1 2013 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distribution Made to Limited Partner, Date of Record					Mar. 29, 2013
Dividend payable date					Apr. 30, 2013
Quarter 2 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date					Jul. 31, 2013
Quarter 2 2013 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distribution Made to Limited Partner, Date of Record					Jun. 28, 2013
Dividend payable date					Jul. 31, 2013
Quarter 3 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date					Oct. 31, 2013
Quarter 3 2013 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distribution Made to Limited Partner, Date of Record					Sep. 30, 2013
Dividend payable date					Oct. 31, 2013
Quarter 4 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date					Jan. 29, 2014
Dividends Payable, Date Declared					Nov. 27, 2013
Quarter 4 2013 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distribution Made to Limited Partner, Date of Record					Dec. 31, 2013
Dividend payable date					Jan. 29, 2014
Dividends Payable, Date Declared					Nov. 27, 2013
special dividend [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distributions Declared To OP And LTIP Units Per Unit							$ 2.25

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) $ in Thousands					12 Months Ended
	May 31, 2013 USD ($) ft² partners	Mar. 26, 2013 USD ($) ft² floor	Feb. 26, 2013	Feb. 07, 2013	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Oct. 09, 2013 USD ($) ft²
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interests recorded upon consolidation					$ 480,861	$ 0	$ 0
Noncontrolling interests in property partnerships					$ 726,132	$ (1,964)
Transbay Tower [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Partners Joint Venture Ownership Percentage			5.00%	50.00%
Ownership Percentage			95.00%
Number of floors in building \| floor		60
Net Rentable Area \| ft²		1,400,000
Payments to Acquire Land		$ 192,000
767 5th Avenue (The General Motors Building) [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Partners Joint Venture Ownership Percentage	40.00%
Net Rentable Area \| ft²	1,800,000
Noncontrolling Interests recorded upon consolidation	$ 480,861
767 5th Avenue (The General Motors Building) [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of Joint Venture Partners \| partners	2
Time Square Tower [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Net Rentable Area \| ft²								1,246,000
ownership interest sold (percent)								45.00%
Net Contractual Sales Price								$ 684,000
Proceeds from sale of an interest in a real estate asset								673,100
Portion allocation to noncontrolling interest based on carrying value of the total equity of the property prior to the sale								243,500
Difference between net cash proceeds received and noncontrolling interest recognized								$ 429,600

Noncontrolling Interests (Redeemable Preferred Units) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Beginning Balance

$ 199,378

$ 145,484

Net income

14,103

3,497

$ 3,339

Redemption of redeemable preferred units (Series Four Preferred Units)

(43,070)

(18,329)

Ending Balance

105,746

199,378

145,484

Redeemable Preferred Units [Member]

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Beginning Balance

125,765

Net income

6,046

3,497

3,339

Distributions

(6,046)

(3,497)

(3,339)

Issuance of redeemable preferred units (Series Four Preferred Units)

79,405

Redemption of redeemable preferred units (Series Four Preferred Units)

(43,070)

(18,329)

Reallocation of partnership interest

$ (50,562)

^[1]

$ (7,182)

^[1]

$ 19,719

Series Two Preferred Units [Member]

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Units converted (in shares)

329,881

117,047

Op Units [Member]

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

Units converted (in shares)

432,914

153,605

[1]	Includes the conversion of 329,881 and 117,047 Series Two Preferred Units into 432,914 and 153,605 OP Units during the years ended December 31, 2013 and 2012, respectively.

Noncontrolling Interests (Noncontrolling Interests-Redeemable Common Units) (Details) - Noncontrolling Interests [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Activity of noncontrolling interests
Beginning Balance	$ 1,836,522	$ 1,809,119	$ 1,801,592
Contributions	26,398	24,588	23,379
Net income	84,236	35,200	36,250
Distributions	(83,448)	(41,434)	(39,132)
Conversion of redeemable partnership units	(30,291)	(34,621)	(85,498)
Unearned compensation	1,472	(883)	(1,952)
Accumulated other comprehensive loss	252	273	297
Adjustments to reflect redeemable partnership units at redemption value	(124,923)	44,280	74,183
Ending Balance	$ 1,710,218	$ 1,836,522	$ 1,809,119

Noncontrolling Interests (Noncontrolling Interests-Property Partnerships) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Activity of noncontrolling interests
Beginning balance	$ (1,964)
Net income (loss)	1,347	$ 3,792	$ 1,558
Fair value of capital recorded upon consolidation	480,861	0	0
Ending balance	726,132	(1,964)
Property Partnerships [Member]
Activity of noncontrolling interests
Beginning balance	(1,964)	(1,063)	(614)
Net income (loss)	(5,290)	1,989	1,558
Distributions	(5,039)	(2,890)	(2,007)
Fair value of capital recorded upon consolidation	480,861
Capital contributions	257,564
Ending balance	$ 726,132	$ (1,964)	$ (1,063)

Noncontrolling Interests Redeemable Interest in Property Partnerships (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Activity of noncontrolling interests
Beginning Balance	$ 97,558	$ 0
Acquisition Date Fair Value of Redeemable Interest		98,787
Net Loss	1,839	719
Distributions	4,585	3,032
Adjustment to Reflect Redeemable Interest at Redemption Value	8,475	2,522
Ending Balance	$ 99,609	$ 97,558

Noncontrolling Interests Redeemable Interest in Property Partnerships (Narrative) (Details) - Fountain Square [Member] $ in Millions	Oct. 04, 2012 USD ($)
Noncontrolling Interest [Line Items]
Aggregate purchase price	$ 385.0
Consideration paid	$ 87.0
Noncontrolling Interest, Ownership Percentage by Parent	50.00%
Future Fixed Price to Acquire Remaining Portion of Joint venture	$ 102.0
Fixed Price Option Expiration Date	Jan. 31, 2016
Debt recorded upon consolidation	$ 211.3
Ownership Percentage	50.00%

Partners' Capital (Details) - USD ($) $ / shares in Units, $ in Thousands									3 Months Ended	9 Months Ended	12 Months Ended
	Nov. 15, 2013	Oct. 31, 2013	Aug. 15, 2013	Jul. 31, 2013	May 15, 2013	Apr. 30, 2013	Mar. 27, 2013	Jan. 29, 2013	Mar. 31, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 27, 2018	Nov. 27, 2013
Class of Stock [Line Items]
General partnership units (in shares)											1,700,222	1,689,580
Limited partnership units (in shares)											151,282,879	149,911,629
Shares of Common Stock upon the exercise of options to purchase Common Stock by certain employees (in shares)											0	22,823	316,159
Shares of its Common Stock in connection with the redemption of an equal number of OP Units (in shares)											929,441	1,110,660	2,919,323
Dividends Payable, Amount Per Share															$ 0.65
Dividend paid on common stock (in dollars per share)		$ 0.65		$ 0.65		$ 0.65		$ 0.65
Proceeds from Issuance of Preferred Stock and Preference Stock							$ 193,600				$ 193,623	$ 0	$ 0
Coupon/Stated Rate (percent)											3.625%
Issued in conjunction with debt exchange for 3.75% exchangeable senior notes [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues											419,116
Coupon/Stated Rate (percent)											3.75%
ATM Program [Member]
Class of Stock [Line Items]
At the market stock offering program, aggregate value of common stock											$ 600,000
At Market Stock Offering Program Remained Available For Issuance											$ 305,300
Quarter 4 2012 [Member]
Class of Stock [Line Items]
Dividend payable date											Jan. 29, 2013
Dividend shareholder of record date											Dec. 31, 2012
Quarter 1 2013 [Member]
Class of Stock [Line Items]
Dividend payable date											Apr. 30, 2013
Dividend shareholder of record date											Mar. 29, 2013
Quarter 2 2013 [Member]
Class of Stock [Line Items]
Dividend payable date											Jul. 31, 2013
Dividend shareholder of record date											Jun. 28, 2013
Quarter 3 2013 [Member]
Class of Stock [Line Items]
Dividend payable date											Oct. 31, 2013
Dividend shareholder of record date											Sep. 30, 2013
Quarter 4 2013 [Member]
Class of Stock [Line Items]
Dividend payable date											Jan. 29, 2014
Dividend shareholder of record date											Dec. 31, 2013
Dividends Payable, Date Declared											Nov. 27, 2013
Depository shares of Series B Cumulative Redeemable Preferred [Member]
Class of Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share											$ 25.00			$ 25.00
Series B Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Ratio of depository shares to shares of Series B Preferred Stock											0.01
Dividends Payable, Amount Per Share															32.8125
Dividend paid on common stock (in dollars per share)	$ 32.8125		$ 32.8125		$ 32.8125
Preferred Stock, Shares Outstanding									80,000		80,000	0
Preferred Stock, Dividend Rate, Percentage									5.25%
Preferred Stock, Liquidation Preference Per Share											$ 2,500.00	$ 0		$ 2,500.00
Series B Cumulative Redeemable Preferred Stock [Member] \| Quarter 2 2013 [Member]
Class of Stock [Line Items]
Dividend payable date											May 15, 2013
Series B Cumulative Redeemable Preferred Stock [Member] \| Quarter 3 2013 [Member]
Class of Stock [Line Items]
Dividend payable date											Aug. 15, 2013
Series B Cumulative Redeemable Preferred Stock [Member] \| Quarter 4 2013 [Member]
Class of Stock [Line Items]
Dividend payable date											Nov. 15, 2013
Series B Cumulative Redeemable Preferred Stock [Member] \| Quarter 1 2014 [Member]
Class of Stock [Line Items]
Dividend payable date											Feb. 18, 2014
Dividend shareholder of record date											Feb. 07, 2014
Dividends Payable, Date Declared											Nov. 27, 2013
Op Units [Member] \| Issued in conjunction with debt exchange for 3.75% exchangeable senior notes [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues										419,116
special dividend [Member]
Class of Stock [Line Items]
Dividends Payable, Amount Per Share															$ 2.25
depositary shares [Member] \| Series B Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Outstanding									8,000,000

Partners' Capital Changes in Issued and Outstanding Partners' Capital Units (Details) - shares	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Limited Partners' Capital Account [Line Items]
General partnership units, beginning balance	1,689,580
Limited partnership units, beginning balance	149,911,629
Partners' Capital Account, Units	151,601,209	148,107,611	140,199,105
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	6,442	7,406	6,356
Units issued to Boston Properties, Inc. related to Common Stock issued under Stock Option and Incentive Plans, net	26,893	28,032	322,611
Units issued to Boston Proeprties, inc. related to Common Stock issued in exchange of OP Units	929,441	1,110,660	2,919,323
Units issued to Boston Properties, Inc. related to Common Stock issued under the at the market (ATM) stock offering program	419,116	2,347,500	4,660,216
General partnership units, ending balance	1,700,222	1,689,580
Limited partnership units, ending balance	151,282,879	149,911,629
Partners' Capital Account, Units	152,983,101	151,601,209	148,107,611
General Partner Units [Member]
Limited Partners' Capital Account [Line Items]
General partnership units, beginning balance	1,689,580	1,662,715	1,610,941
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	50	57	42
Units issued to Boston Properties, Inc. related to Common Stock issued under Stock Option and Incentive Plans, net	207	216	2,112
Units issued to Boston Proeprties, inc. related to Common Stock issued in exchange of OP Units	7,158	8,541	19,112
Units issued to Boston Properties, Inc. related to Common Stock issued under the at the market (ATM) stock offering program	3,227	18,051	30,508
General partnership units, ending balance	1,700,222	1,689,580	1,662,715
Limited Partner Units [Member]
Limited Partners' Capital Account [Line Items]
Limited partnership units, beginning balance	149,911,629	146,444,896	138,588,164
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	6,392	7,349	6,314
Units issued to Boston Properties, Inc. related to Common Stock issued under Stock Option and Incentive Plans, net	26,686	27,816	320,499
Units issued to Boston Proeprties, inc. related to Common Stock issued in exchange of OP Units	922,283	1,102,119	2,900,211
Units issued to Boston Properties, Inc. related to Common Stock issued under the at the market (ATM) stock offering program	415,889	2,329,449	4,629,708
Limited partnership units, ending balance	151,282,879	149,911,629	146,444,896

Partners' Capital Change in Series B Preferred Units (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2013 USD ($)
Statement of Partners' Capital [Abstract]
Beginning Balance	$ 0
Issuance of Series B Preferred Units	193,623
Net income	8,057
Distributions	(8,057)
Ending Balance	$ 193,623

Future Minimum Rents Schedule of Future Minimum Renal Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2013 USD ($)
Future Minimum Rents [Abstract]
2014	$ 1,716,754
2015	1,706,282
2016	1,660,890
2017	1,510,645
2018	1,342,157
Thereafter	$ 6,674,466

Future Minimum Rents Narrative (Details) - tenants	12 Months Ended
Future Minimum Rents Narrative (Details) - tenants	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Future Minimum Rent [Line Items]
Number Of Tenants Above Concentration Amount.	0	0	0
Concentration Risk, Percentage	10.00%	10.00%	10.00%
Minimum [Member]
Future Minimum Rent [Line Items]
Initial Term Lease Expiration Date	2014
Maximum [Member]
Future Minimum Rent [Line Items]
Initial Term Lease Expiration Date	2048

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office									$ 1,987,671	$ 1,715,425	$ 1,606,655
Rental Revenue: Office/Technical									55,525	39,218	41,585
Rental Revenue: Residential									22,318	20,568	6,617
Rental Revenue: Hotel									40,330	37,915	34,529
Rental Revenue Total									2,105,844	1,813,126	1,689,386
Total revenue	$ 576,199	$ 571,481	$ 510,033	$ 477,826	$ 478,047	$ 464,220	$ 466,197	$ 438,722	$ 2,135,539	$ 1,847,186	$ 1,722,792
Rental Revenue: % of Grand Totals									100.00%	100.00%	100.00%
Rental Expenses: Class A Office									$ 716,049	$ 617,482	$ 555,664
Rental Expenses: Office/Technical									14,777	10,614	11,525
Rental Expenses: Residential									12,130	10,992	5,479
Rental Expenses: Hotel									28,447	28,120	26,128
Rental Expenses: Total									$ 771,403	$ 667,208	$ 598,796
Rental Expenses: % Of Grand Totals									100.00%	100.00%	100.00%
Net Operating Income									$ 1,334,441	$ 1,145,918	$ 1,090,590
Net Operating Income: % of Grand Totals									100.00%	100.00%	100.00%
Boston [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office									$ 665,991	$ 617,652	$ 537,743
Rental Revenue: Office/Technical									22,617	22,460	25,349
Rental Revenue: Residential									4,395	3,936	985
Rental Revenue: Hotel									40,330	37,915	34,529
Rental Revenue Total									$ 733,333	$ 681,963	$ 598,606
Rental Revenue: % of Grand Totals									34.82%	37.61%	35.43%
Rental Expenses: Class A Office									$ 259,997	$ 242,904	$ 206,469
Rental Expenses: Office/Technical									6,879	6,499	7,245
Rental Expenses: Residential									1,823	1,675	521
Rental Expenses: Hotel									28,447	28,120	26,128
Rental Expenses: Total									$ 297,146	$ 279,198	$ 240,363
Rental Expenses: % Of Grand Totals									38.52%	41.85%	40.14%
Net Operating Income									$ 436,187	$ 402,765	$ 358,243
Net Operating Income: % of Grand Totals									32.69%	35.15%	32.85%
New York [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office									$ 725,566	$ 543,194	$ 521,439
Rental Revenue: Office/Technical									0	0	0
Rental Revenue: Residential									0	0	0
Rental Revenue: Hotel									0	0	0
Rental Revenue Total									$ 725,566	$ 543,194	$ 521,439
Rental Revenue: % of Grand Totals									34.46%	29.96%	30.87%
Rental Expenses: Class A Office									$ 251,640	$ 187,987	$ 181,269
Rental Expenses: Office/Technical									0	0	0
Rental Expenses: Residential									0	0	0
Rental Expenses: Hotel									0	0	0
Rental Expenses: Total									$ 251,640	$ 187,987	$ 181,269
Rental Expenses: % Of Grand Totals									32.62%	28.18%	30.27%
Net Operating Income									$ 473,926	$ 355,207	$ 340,170
Net Operating Income: % of Grand Totals									35.51%	31.00%	31.19%
San Francisco [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office									$ 214,755	$ 208,177	$ 207,003
Rental Revenue: Office/Technical									17,259	494	0
Rental Revenue: Residential									0	0	0
Rental Revenue: Hotel									0	0	0
Rental Revenue Total									$ 232,014	$ 208,671	$ 207,003
Rental Revenue: % of Grand Totals									11.02%	11.51%	12.25%
Rental Expenses: Class A Office									$ 77,905	$ 75,542	$ 72,122
Rental Expenses: Office/Technical									3,708	149	0
Rental Expenses: Residential									0	0	0
Rental Expenses: Hotel									0	0	0
Rental Expenses: Total									$ 81,613	$ 75,691	$ 72,122
Rental Expenses: % Of Grand Totals									10.58%	11.34%	12.05%
Net Operating Income									$ 150,401	$ 132,980	$ 134,881
Net Operating Income: % of Grand Totals									11.27%	11.60%	12.37%
Washington, DC [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office									$ 381,359	$ 346,402	$ 340,470
Rental Revenue: Office/Technical									15,649	16,264	16,236
Rental Revenue: Residential									17,923	16,632	5,632
Rental Revenue: Hotel									0	0	0
Rental Revenue Total									$ 414,931	$ 379,298	$ 362,338
Rental Revenue: % of Grand Totals									19.70%	20.92%	21.45%
Rental Expenses: Class A Office									$ 126,507	$ 111,049	$ 95,804
Rental Expenses: Office/Technical									4,190	3,966	4,280
Rental Expenses: Residential									10,307	9,317	4,958
Rental Expenses: Hotel									0	0	0
Rental Expenses: Total									$ 141,004	$ 124,332	$ 105,042
Rental Expenses: % Of Grand Totals									18.28%	18.63%	17.54%
Net Operating Income									$ 273,927	$ 254,966	$ 257,296
Net Operating Income: % of Grand Totals									20.53%	22.25%	23.59%

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership
Development and management services income									$ 29,695	$ 34,060	$ 33,406
Income from unconsolidated joint ventures									75,074	49,078	85,896
Gains on consolidation of joint ventures									385,991	0	0
Interest and other income									8,310	10,091	5,358
Gains (losses) from investments in securities									2,911	1,389	(443)
Gains (losses) from early extinguishments of debt									122	(4,453)	(1,494)
Income from discontinued operations									8,022	9,806	10,876
Gain on sale of real estate from discontinued operations									115,459	38,445	0
Gain on forgiveness of debt from discontinued operations									20,736	0	0
General and administrative expense									115,329	90,129	87,101
Transaction costs									1,744	3,653	1,987
Depreciation and amortization expense									552,589	437,692	421,519
Interest expense									446,880	410,970	391,533
Impairment loss									4,401	0	0
Impairment loss from discontinued operations									2,852	0	0
Noncontrolling interest in property partnerships									1,347	3,792	1,558
Noncontrolling interest-redeemable preferred units									14,103	3,497	3,339
Net income attributable to Boston Properties Limited Partnership	$ 101,264	$ 174,140	$ 505,189	$ 60,923	$ 75,264	$ 66,234	$ 136,561	$ 56,542	841,516	334,601	317,152
Business Intersegment, Eliminations [Member]
Reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership
Net Operating Income									1,334,441	1,145,918	1,090,590
Development and management services income									29,695	34,060	33,406
Income from unconsolidated joint ventures									75,074	49,078	85,896
Gains on consolidation of joint ventures									385,991	0	0
Interest and other income									8,310	10,091	5,358
Gains (losses) from investments in securities									2,911	1,389	(443)
Gains (losses) from early extinguishments of debt									122	(4,453)	(1,494)
Income from discontinued operations									8,022	9,806	10,876
Gain on sale of real estate from discontinued operations									115,459	38,445	0
Gain on forgiveness of debt from discontinued operations									20,736	0	0
General and administrative expense									115,329	90,129	87,101
Transaction costs									1,744	3,653	1,987
Depreciation and amortization expense									552,589	437,692	421,519
Interest expense									446,880	410,970	391,533
Impairment loss									4,401	0	0
Impairment loss from discontinued operations									2,852	0	0
Noncontrolling interest in property partnerships									1,347	3,792	1,558
Noncontrolling interest-redeemable preferred units									14,103	3,497	3,339
Net income attributable to Boston Properties Limited Partnership									$ 841,516	$ 334,601	$ 317,152

Segment Information Segment reporting (narrative) (Details) $ in Millions		12 Months Ended
	May 31, 2013 partners	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)
Segment Reporting Information [Line Items]
Reclassification between general and administrative expense and real estate operating expenses		$ 8.1	$ 7.7	$ 7.5
Princeton [Member]
Segment Reporting Information [Line Items]
Reclassification between general and administrative expense and real estate operating expenses		1.4	1.6	1.5
San Francisco [Member]
Segment Reporting Information [Line Items]
Reclassification between general and administrative expense and real estate operating expenses		$ 6.7	$ 6.1	$ 6.0
767 5th Avenue (The General Motors Building) [Member]
Segment Reporting Information [Line Items]
Number of Joint Venture Partners \| partners	2

Earnings Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Redeemable common units (in shares)									16,925,000	17,649,000	18,793,000
Basic Earnings:
Income from continuing operations attributable to Boston Properties Limited Partnership, Income (Numerator)	$ 81,412	$ 84,348	$ 505,396	$ 44,445	$ 76,295	$ 65,375	$ 96,836	$ 55,133	$ 700,151	$ 286,350	$ 306,276
Net income attributable to Boston Properties Limited Partnership, Units (Denominator) (in shares)									169,126,000	167,769,000	164,486,000
Income from continuing operations attributable to Boston Properties Limited Partnership, Per Unit Amount (in dollars per share)									$ 4.14	$ 1.70	$ 1.86
Discontinued operations attributable to Boston Properties Limited Partnership, Income (Numerator)									$ 141,365	$ 48,251	$ 10,876
Discontinued operations attributable to Boston Properties Limited Partnership, Per Unit Amount (in dollars per share)									$ 0.84	$ 0.29	$ 0.07
Allocation of undistributed earnings to participating securities									$ (178)
Allocation of undistributed earnings to participating securities ($ per shares)									$ (0.01)
Net income attributable to Boston Properties Limited Partnership									$ 841,338	$ 334,601	$ 317,152
Net income (in dollars per share)	$ 0.60	$ 1.03	$ 2.97	$ 0.36	$ 0.45	$ 0.39	$ 0.81	$ 0.34	$ 4.97	$ 1.99	$ 1.93
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes, Income (Numerator)									$ 0	$ 0	$ 0
Stock Based Compensation and Exchangeable Senior Notes, Units (Denominator) (in shares)									320,000	591,000	525,000
Stock Based Compensation and Exchangeable Senior Notes, Per Unit Amount (in dollars per share)									$ 0.00	$ 0.00	$ (0.01)
Diluted Earnings:
Diluted Earnings: Net income, Income (Numerator)									$ 841,338	$ 334,601	$ 317,152
Diluted Earnings: Net income, Units (Denominator) (in shares)									169,446,000	168,360,000	165,011,000
Diluted Earnings: Net income, Per Unit Amount (in dollars per share)	$ 0.60	$ 1.02	$ 2.96	$ 0.36	$ 0.45	$ 0.39	$ 0.81	$ 0.34	$ 4.97	$ 1.99	$ 1.92

Employee Benefit Plans (Details)	12 Months Ended			156 Months Ended	168 Months Ended	180 Months Ended
Employee Benefit Plans (Details)	Dec. 31, 2013 USD ($) mo	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2013 USD ($) age yr	Dec. 31, 2013 USD ($)	Dec. 31, 1999
Employee Benefit Plans [Abstract]
Eligibility Period For 401K Savings Plan In Months \| mo	3
Employer Matching Contribution, Percent of Match					200.00%	200.00%
Employer Matching Contribution, Percent of Employees' Gross Pay					3.00%	2.00%
Maximum Eligible Earnings As Established By IRS For Matching Contributions	$ 255,000	$ 250,000	$ 245,000
Employer Contribution Amount	3,400,000	3,200,000	3,100,000
Years Of Service For Supplemental Retirement Contribution \| yr				10
Age Of Employee For Supplemental Retirement Contribution \| age				40
Annual Supplemental Retirement Contribution And Credit Total.	60,000	78,000	$ 62,000
Separate Unrestricted Cash For Deferred Compensation Plan.	16,600,000	12,200,000		$ 16,600,000	$ 16,600,000
Deferred Compensation Liability	$ 16,600,000	$ 12,200,000		$ 16,600,000	$ 16,600,000

Stock Option and Incentive Plan (Narrative) (Details)			12 Months Ended
Stock Option and Incentive Plan (Narrative) (Details)	Jan. 28, 2013 USD ($) indices yr	May 15, 2012 yr shares	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Jan. 31, 2014 shares	Apr. 02, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 43,900,000	$ 28,300,000	$ 28,300,000
LTIP units issued (in shares) \| shares						109,718
Two Thousand Twelve Stock Option and Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Additional Shares Authorized \| shares		13,000,000
Other Than Stock Options Awards Conversion Ratio		2.32
Stock Option Awards Conversion Ratio		1.0
Stock Option and Incentive Plan Term Period \| yr		10
MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
TRS measurement (in years) \| yr	3
Distributions percent before measurement date	10.00%
Indices Used to Compare TRS \| indices	2
Number of Tiers	4
Percentage of annualized TRS for Reduction of Earned Awards	2.00%
Percentage to Cause Some Awards to be Earned Even if on a Relative Basis it Would Not Result in any Earned Awards	10.00%
Target [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier	$ 10,200,000
Minimum [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned	0
Maximum [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned	30,700,000
Threshold [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier	5,100,000
High [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier	20,500,000
Exceptional [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier	$ 30,700,000
Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares) \| shares							24,231
Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			21,500,000
Compensation Expense associated with Transition Agreement			13,800,000
Executive Vice President [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense			$ 2,700,000
Cohen & Steers Realty Majors Portfolio Index [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Percentage of Index Used to Compare to TRS	50.00%
NAREIT Office Index adjusted [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Percentage of Index Used to Compare to TRS	50.00%
MYLTIP Vesting 2016 [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage	25.00%
Vesting Date	Feb. 04, 2016
MYLTIP Vesting 2017 [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage	25.00%
Vesting Date	Feb. 04, 2017
MYLTIP Vesting 2018 [Member] \| MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage	50.00%
Vesting Date	Feb. 04, 2018

Stock Option and Incentive Plan (Restricted Stock) (Narrative) (Details) $ / shares in Units, $ in Millions			9 Months Ended	12 Months Ended
	Jan. 31, 2014 $ / shares shares	Jan. 28, 2013 USD ($) yr	Sep. 30, 2013 USD ($)	Dec. 31, 2013 USD ($) VestingInstallments d $ / shares shares	Dec. 31, 2012 USD ($) $ / shares yr shares	Dec. 31, 2011 USD ($) $ / shares shares	Apr. 02, 2013 shares	Mar. 11, 2013 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares) \| shares	109,718
Stock-based compensation associated with restricted stock, non-qualified options, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units				$ 43.9	$ 28.3	$ 28.3
Accelerated Compensation Expenses Related To 2008 Opp Units						$ 4.3
Weighted-average grant date fair value (in dollars per share) \| $ / shares				$ 104.50	$ 107.23	$ 92.71
Exercisable, Weighted Average Exercise Price \| $ / shares					$ 98.92	$ 54.32
Number Exercisable at 12/31/2010 \| shares					91,496	13,633
Total intrinsic value of the outstanding and exercisable stock options				$ 0.8
Cash Payment Related to Transition Agreement								$ 6.7
MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued \| shares				318,926
TRS measurement (in years) \| yr		3
Value of MYLTIP Awards		$ 9.2
MYLTIP Value Amortized Into Earnings, Years \| yr		5
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued \| shares				36,730	20,756	19,030
Employee and director payment per share (in dollars per share) \| $ / shares				$ 0.01
Value of shares of common stock				$ 3.9	$ 2.2	$ 1.8
Employee's weighted average cost per share (in dollars per share) \| $ / shares				$ 105.30	$ 107.31	$ 93.40
Ltip Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares) \| shares				184,733	174,650	190,067
Value Of LTIP Units Issued				$ 17.8	$ 17.3	$ 16.5
Per unit fair value weighted-average (in dollars per share) \| $ / shares				$ 96.13	$ 98.83	$ 86.74
Expected life assumed to calculate per unit fair value per LTIP unit (years)				5 years 8 months 12 days	5 years 9 months 19 days	5 years 9 months 19 days
Risk-free rate				1.03%	0.94%	2.22%
Expected price volatility				26.00%	29.10%	30.00%
Opp Units Two Thousand And Eight [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
TRS measurement (in years) \| yr					3
LTIPS And Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Annual Installments \| VestingInstallments				4
Unrecognized compensation expenses				$ 17.6
LTIPS, OPP and MYLTIP Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share) \| $ / shares				$ 0.25
OPP Units 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
2012 OPP units issued (in shares) \| shares					400,000
Non Qualified Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-qualified stock options issued (in shares) \| shares				252,220	186,007	146,844
Expected life assumed to calculate per unit fair value per LTIP unit (years)				6 years	5 years 4 months 24 days	6 years
Risk-free rate				1.11%	0.92%	2.37%
Expected price volatility				26.00%	28.40%	35.00%
Expected dividend rate				3.00%	2.90%	3.00%
Weighted-average grant date fair value (in dollars per share) \| $ / shares				$ 18.46	$ 19.50	$ 24.67
Weighted-average exercise price (in dollars per share) \| $ / shares				$ 105.10	$ 107.23	$ 92.71
OPP Units 2011 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
2012 OPP units issued (in shares) \| shares						400,000
Employee and director payment per share (in dollars per share) \| $ / shares	$ 0.25
Unvested 2011 and 2012 OPP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses				$ 11.1
Weighted-average period (years)				2 years 8 months 12 days
Non-Qualified Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum Common Stock available for issuance \| shares				250,000
Employee Common Stock options, percent of average closing price				85.00%
Number Of Days Used In Calculation, Average Closing Prices Of Common Stock \| d				10
Shares issued \| shares				6,442	7,406	6,356
Shares issued, weighted-average purchase price per share \| $ / shares				$ 89.65	$ 86.52	$ 80.13
Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares) \| shares							24,231
MYLTIP units issued \| shares							38,926
Non-qualified stock options issued (in shares) \| shares							50,847
Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation associated with restricted stock, non-qualified options, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units				$ 21.5
Compensation Expense associated with Transition Agreement				13.8
Target Equity Award Compensation Associated with Transition Agreement								$ 11.1
Acceleration of Stock Based Compensation in Association with Transition Agreement			$ 12.9
Executive Vice President [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation associated with restricted stock, non-qualified options, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units				$ 2.7

Stock Option and Incentive Plan Schedule of Stock Options Status (Details) - $ / shares	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning Outstanding, Shares	294,527	155,623	324,938
Beginning Oustanding, Weighted Average Exercise Price	$ 101.06	$ 89.35	$ 32.65
Granted, Shares	252,220	186,007	146,844
Granted, Weighted Average Exercise Price	$ 104.50	$ 107.23	$ 92.71
Exercised, Shares	0	22,823	316,159
Exercised, Weighted Averge Exercise Price	$ 0.00	$ 72.42	$ 32.63
Canceled, Shares	0	(24,280)	0
Canceled, Weighted Average Exercise Price	$ 0.00	$ 100.15	$ 0
Special dividend adjustment shares	12,076
Special dividend adjustment, weighted average exercise price	$ 100.44
Ending Outstanding, Shares	558,823	294,527	155,623
Ending Oustanding, Weighted Average Exercise Price	$ 100.43	$ 101.06	$ 89.35

Stock Option and Incentive Plan Schedule of Stock Options Outstanding (Details) - $ / shares	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding at 12/31/13	558,823	294,527	155,623	324,938
Outstanding, Weighted Average Exercise Price	$ 100.43	$ 101.06	$ 89.35	$ 32.65
Number Exercisable at 12/31/13		91,496	13,633
Exercisable, Weighted Average Exercise Price		$ 98.92	$ 54.32
Exercise Price of $90.71 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 90.71
Weighted Average Remaining Contractual Life (Years)	7 years 1 month 6 days
Number Outstanding at 12/31/13	131,837
Outstanding, Weighted Average Exercise Price	$ 90.71
Number Exercisable at 12/31/13	80,240
Exercisable, Weighted Average Exercise Price	$ 90.71
Exercise Price of $99.94 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 99.94
Weighted Average Remaining Contractual Life (Years)	9 years 3 months 18 days
Number Outstanding at 12/31/13	51,971
Outstanding, Weighted Average Exercise Price	$ 99.94
Number Exercisable at 12/31/13	0
Exercisable, Weighted Average Exercise Price	$ 0.00
Exercise Price of $102.83 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 102.83
Weighted Average Remaining Contractual Life (Years)	9 years 1 month 6 days
Number Outstanding at 12/31/13	205,821
Outstanding, Weighted Average Exercise Price	$ 102.83
Number Exercisable at 12/31/13	48,026
Exercisable, Weighted Average Exercise Price	$ 102.83
Exercise Price of $105.25 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 105.25
Weighted Average Remaining Contractual Life (Years)	8 years 1 month 6 days
Number Outstanding at 12/31/13	169,194
Outstanding, Weighted Average Exercise Price	$ 105.25
Number Exercisable at 12/31/13	71,602
Exercisable, Weighted Average Exercise Price	$ 105.25

Related Party Transactions (Details)			12 Months Ended					76 Months Ended	110 Months Ended	186 Months Ended
Related Party Transactions (Details)	Jul. 24, 2007	Jun. 30, 1998	Dec. 31, 2013 USD ($) nonemployeedirectors	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2007 USD ($)	Dec. 31, 2004 USD ($)	Oct. 20, 2004	Dec. 31, 2013 USD ($)	Dec. 31, 2013 USD ($) ft² yr
Related Party Transaction [Line Items]
Number Of Non employee Directors Electing To Receive Deferred Stock Units \| nonemployeedirectors			6
Deferred Stock Units Outstanding			83,995	76,682					83,995	83,995
New York regional manager [Member]
Related Party Transaction [Line Items]
Aggregate leasing commissions paid to related parties			$ 592,000
Brother of Executive Vice President [Member]
Related Party Transaction [Line Items]
Aggregate leasing commissions paid to related parties			868,000	$ 1,306,000	$ 671,000
Former Director [Member]
Related Party Transaction [Line Items]
Related Party Acquisition Date	Jul. 24, 2007	Jun. 30, 1998
Purchase Price of Land Parcel						$ 3,100,000
Annual Development Agreement Payments.			$ 125,000
Development Agreement Payment Made For 1998 Through 2004							$ 750,000
Affiliate of Former Director [Member]
Related Party Transaction [Line Items]
Purchase price per rentable square feet of property developed.										$ 20
Target Annual Return Minimum								10.50%
Target Annual Return Maximum.								11.00%
Aggregate Fixed Rentable Per Square Foot Of Developed Property.									$ 10.50
Term of Development Agreement., Years \| yr										20
Square Feet of Development \| ft²										2,000,000
Adjustment To Aggregate Fixed Amount Per Square Foot Of Developed Property									$ 5.50

Selected Interim Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 576,199	$ 571,481	$ 510,033	$ 477,826	$ 478,047	$ 464,220	$ 466,197	$ 438,722	$ 2,135,539	$ 1,847,186	$ 1,722,792
Income from continuing operations	81,412	84,348	505,396	44,445	76,295	65,375	96,836	55,133	700,151	286,350	306,276
Net income attributable to Boston Properties Limited Partnership	$ 101,264	$ 174,140	$ 505,189	$ 60,923	$ 75,264	$ 66,234	$ 136,561	$ 56,542	$ 841,516	$ 334,601	$ 317,152
Income attributable to Boston Properties Limited Partnership per share - basic	$ 0.60	$ 1.03	$ 2.97	$ 0.36	$ 0.45	$ 0.39	$ 0.81	$ 0.34	$ 4.97	$ 1.99	$ 1.93
Income attributable to Boston Properties Limited Partnership per share - diluted	$ 0.60	$ 1.02	$ 2.96	$ 0.36	$ 0.45	$ 0.39	$ 0.81	$ 0.34	$ 4.97	$ 1.99	$ 1.92

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References + Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Subsequent Events Subsequent Events (Details)				12 Months Ended
Subsequent Events Subsequent Events (Details)	Feb. 18, 2014 USD ($)	Jan. 31, 2014 USD ($) $ / shares shares	Jan. 27, 2014 USD ($) indices tiers yr	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Feb. 10, 2014 ft² apartments
Subsequent Event [Line Items]
Repayments of Unsecured Debt				$ 0	$ 224,261,000	$ 0
Coupon/Stated Rate (percent)				3.625%
LTIP units issued (in shares) \| shares		109,718
MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Indices Used to Compare TRS \| indices			2
Number of Tiers \| tiers			4
Percentage to Cause Some Awards to be Earned Even if on a Relative Basis it Would Not Result in any Earned Awards			12.00%
Percentage of annualized TRS for Reduction of Earned Awards			0.00%
Distributions percent before measurement date			10.00%
Value of MYLTIP Awards			$ 13,100,000
TRS measurement (in years) \| yr			3
OPP Units 2011 [Member]
Subsequent Event [Line Items]
Employee and director payment per share (in dollars per share) \| $ / shares		$ 0.25
Accelerated Compensation Expenses Related To 2011 OPP Units		$ 1,200,000
Cohen & Steers Realty Majors Portfolio Index [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Weighted Percentage of Index Used to Compare to TRS			50.00%
NAREIT Office Index adjusted [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Weighted Percentage of Index Used to Compare to TRS			50.00%
Minimum [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Potential Awards Earned			$ 0
Maximum [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Potential Awards Earned			40,200,000
Threshold [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Amount of Each Tier			6,700,000
Target [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Amount of Each Tier			13,400,000
High [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Amount of Each Tier			26,800,000
Exceptional [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Amount of Each Tier			$ 40,200,000
MYLTIP vesting 2018 [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Vesting Percentage			50.00%
Vesting Date			Feb. 03, 2018
MYLTIP Vesting 2017 [Member] \| MYLTIP 2014 [Member]
Subsequent Event [Line Items]
Vesting Percentage			50.00%
Vesting Date			Feb. 03, 2017
Restricted Stock [Member]
Subsequent Event [Line Items]
Shares issued \| shares		21,455
The Avant at Reston Town Center Residential [Member]
Subsequent Event [Line Items]
Number of apartment units \| apartments							359
Net Rentable Area \| ft²							355,000
3.625% Exchangeable Senior Notes [Member]
Subsequent Event [Line Items]
Repayments of Unsecured Debt	$ 747,500,000
Coupon/Stated Rate (percent)	3.625%

Real Estate and Accumulated Depreciation Schedule of Real Estate and Accumulated Depreciation (details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2013

Dec. 31, 2012

Real Estate and Accumulated Depreciation [Line Items]

Encumbrances

^[1]

$ 4,449,734

Original Land

4,303,172

Original Buildings

10,631,057

Costs Capitalized Subsequent to Acquisition

3,589,048

Land and Improvements

4,342,951

Buildings and Improvements

12,359,771

Land Held for Development

297,376

Development and Construction in Progress

1,523,179

Total

18,523,277

Accumulated Depreciation

3,081,040

Furniture and Fixtures, Gross

25,164

$ 23,441

Accumulated depreciation, furniture, fixtures and equipment

15,870

Real Estate Aggregate Cost For Tax Purposes

16,500,000

Real Estate Aggregate Accumulated Depreciation For Tax Purposes

$ 2,900,000

Real Estate and Accumulated Depreciation, Life Used for Depreciation

40 years

Unamoritzed balance of histroical fair value adjustments

$ 191,204

767 5th Avenue (The General Motors Building) [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

767 Fifth Avenue (The General Motors Building)

Office

New York, NY

$ 1,463,143

1,796,252

1,532,654

Costs Capitalized Subsequent to Acquisition

4,481

Land and Improvements

1,796,252

Buildings and Improvements

1,537,135

Land Held for Development

Development and Construction in Progress

Total

3,333,387

Accumulated Depreciation

$ 28,901

Year(s) Built / Renovation

1968

Depreciable Lives (Years)

-1

Embarcadero Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Embarcadero Center

Office

San Francisco, CA

$ 360,133

179,697

847,410

Costs Capitalized Subsequent to Acquisition

251,913

Land and Improvements

180,420

Buildings and Improvements

1,098,600

Land Held for Development

Development and Construction in Progress

Total

1,279,020

Accumulated Depreciation

$ 462,898

Year(s) Built / Renovation

1970/1989

Depreciable Lives (Years)

-1

Prudential Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Prudential Center

Office

Boston, MA

$ 92,077

734,594

Costs Capitalized Subsequent to Acquisition

294,125

Land and Improvements

92,328

Buildings and Improvements

1,012,537

Land Held for Development

15,931

Development and Construction in Progress

Total

1,120,796

Accumulated Depreciation

$ 389,841

Year(s) Built / Renovation

1965/1993/2002

Depreciable Lives (Years)

-1

399 Park Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

399 Park Avenue

Office

New York, NY

$ 339,200

700,358

Costs Capitalized Subsequent to Acquisition

47,996

Land and Improvements

339,200

Buildings and Improvements

748,354

Land Held for Development

Development and Construction in Progress

Total

1,087,554

Accumulated Depreciation

$ 210,957

Year(s) Built / Renovation

1961

Depreciable Lives (Years)

-1

The John Hancock Tower And Garage [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

The John Hancock Tower and Garage

Office

Boston, MA

$ 652,933

219,543

667,884

Costs Capitalized Subsequent to Acquisition

57,420

Land and Improvements

219,616

Buildings and Improvements

724,812

Land Held for Development

419

Development and Construction in Progress

Total

944,847

Accumulated Depreciation

$ 78,366

Year(s) Built / Renovation

1976

Depreciable Lives (Years)

-1

601 Lexington Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

601 Lexington Avenue

Office

New York, NY

$ 722,253

241,600

494,782

Costs Capitalized Subsequent to Acquisition

175,736

Land and Improvements

279,281

Buildings and Improvements

632,837

Land Held for Development

Development and Construction in Progress

Total

912,118

Accumulated Depreciation

$ 199,519

Year(s) Built / Renovation

1977/1997

Depreciable Lives (Years)

-1

Times Square Tower [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Times Square Tower

Office

New York, NY

$ 165,413

380,438

Costs Capitalized Subsequent to Acquisition

47,167

Land and Improvements

159,694

Buildings and Improvements

433,324

Land Held for Development

Development and Construction in Progress

Total

593,018

Accumulated Depreciation

$ 132,227

Year(s) Built / Renovation

2004

Depreciable Lives (Years)

-1

100 Federal Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

100 Federal Street

Office

Boston, MA

$ 0

131,067

435,954

Costs Capitalized Subsequent to Acquisition

6,020

Land and Improvements

131,067

Buildings and Improvements

441,760

Land Held for Development

214

Development and Construction in Progress

Total

573,041

Accumulated Depreciation

$ 29,060

Year(s) Built / Renovation

1971-1975

Depreciable Lives (Years)

^[2]

-1

Carnegie Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Carnegie Center

Office

Princeton, NJ

$ 105,107

377,259

Costs Capitalized Subsequent to Acquisition

49,548

Land and Improvements

98,733

Buildings and Improvements

430,830

Land Held for Development

2,206

Development and Construction in Progress

145

Total

531,914

Accumulated Depreciation

$ 166,983

Year(s) Built / Renovation

1983-1999

Depreciable Lives (Years)

-1

Fountain Square [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Fountain Square

Office

Reston, VA

$ 226,604

56,853

306,298

Costs Capitalized Subsequent to Acquisition

3,877

Land and Improvements

56,853

Buildings and Improvements

310,175

Land Held for Development

Development and Construction in Progress

Total

367,028

Accumulated Depreciation

$ 15,460

Year(s) Built / Renovation

1986-1990

Depreciable Lives (Years)

^[2]

-1

510 Madison Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

510 Madison Avenue

Office

New York, NY

$ 0

103,000

253,665

Costs Capitalized Subsequent to Acquisition

6,309

Land and Improvements

103,000

Buildings and Improvements

259,974

Land Held for Development

Development and Construction in Progress

Total

362,974

Accumulated Depreciation

$ 15,901

Year(s) Built / Renovation

2012

Depreciable Lives (Years)

^[2]

-1

Atlantic Wharf [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Atlantic Wharf

Office

Boston, MA

$ 63,988

454,537

Costs Capitalized Subsequent to Acquisition

11,644

Land and Improvements

63,988

Buildings and Improvements

466,181

Land Held for Development

Development and Construction in Progress

Total

530,169

Accumulated Depreciation

$ 39,697

Year(s) Built / Renovation

2011

Depreciable Lives (Years)

^[2]

-1

599 Lexington Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

599 Lexington Avenue

Office

New York, NY

$ 750,000

81,040

100,507

Costs Capitalized Subsequent to Acquisition

95,937

Land and Improvements

81,040

Buildings and Improvements

196,444

Land Held for Development

Development and Construction in Progress

Total

277,484

Accumulated Depreciation

$ 140,007

Year(s) Built / Renovation

1986

Depreciable Lives (Years)

-1

Gateway Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Gateway Center

Office

San Francisco, CA

$ 28,255

139,245

Costs Capitalized Subsequent to Acquisition

44,941

Land and Improvements

29,029

Buildings and Improvements

183,412

Land Held for Development

Development and Construction in Progress

Total

212,441

Accumulated Depreciation

$ 79,502

Year(s) Built / Renovation

1984/1986/2002

Depreciable Lives (Years)

-1

Bay Colony Corporate Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Bay Colony Corporate Center

Office

Waltham, MA

$ 18,789

148,451

Costs Capitalized Subsequent to Acquisition

47,332

Land and Improvements

18,789

Buildings and Improvements

195,783

Land Held for Development

Development and Construction in Progress

Total

214,572

Accumulated Depreciation

$ 21,339

Year(s) Built / Renovation

1985-1989

Depreciable Lives (Years)

-1

South of Market and Democracy Tower [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

South of Market and Democracy Tower

Office

Reston, VA

$ 13,603

237,479

Costs Capitalized Subsequent to Acquisition

9,454

Land and Improvements

13,603

Buildings and Improvements

246,933

Land Held for Development

Development and Construction in Progress

Accumulated Depreciation

$ 50,795

Year(s) Built / Renovation

2008-2009

Depreciable Lives (Years)

-1

Mountain View Research [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Mountain View Research Park

Office

Mountain View, CA

$ 106,162

76,137

Costs Capitalized Subsequent to Acquisition

2,196

Land and Improvements

106,162

Buildings and Improvements

78,333

Land Held for Development

Development and Construction in Progress

Total

184,495

Accumulated Depreciation

$ 3,013

Year(s) Built / Renovation

1977-1981/2007-2013

Depreciable Lives (Years)

-1

One and Two Patriots Park [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

One and Two Patriots Park

Office

Reston, VA

$ 0

18,429

126,315

Costs Capitalized Subsequent to Acquisition

28,699

Land and Improvements

20,777

Buildings and Improvements

152,666

Land Held for Development

Development and Construction in Progress

Total

173,443

Accumulated Depreciation

$ 6,084

Year(s) Built / Renovation

1987/1988/2012/2013

Depreciable Lives (Years)

^[2]

-1

2200 Pennsylvania Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

2200 Pennsylvania Avenue

Type

Office

Location

Washington, DC

Original Buildings

$ 183,541

Costs Capitalized Subsequent to Acquisition

3,767

Land and Improvements

Buildings and Improvements

187,308

Land Held for Development

Development and Construction in Progress

Total

187,308

Accumulated Depreciation

$ 18,185

Year(s) Built / Renovation

2011

Depreciable Lives (Years)

-1

3200 Zanker Road [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

3200 Zanker Road

Office

San Jose, CA

$ 36,705

82,863

Costs Capitalized Subsequent to Acquisition

23,501

Land and Improvements

36,705

Buildings and Improvements

102,620

Land Held for Development

3,744

Development and Construction in Progress

Total

143,069

Accumulated Depreciation

$ 22,994

Year(s) Built / Renovation

1988

Depreciable Lives (Years)

^[2]

-1

Reservoir Place [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Reservoir Place

Office

Waltham, MA

$ 18,605

92,619

Costs Capitalized Subsequent to Acquisition

23,371

Land and Improvements

19,099

Buildings and Improvements

115,496

Land Held for Development

Development and Construction in Progress

Total

134,595

Accumulated Depreciation

$ 52,216

Year(s) Built / Renovation

1955/1987

Depreciable Lives (Years)

-1

505 9th Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

505 9th Street

Office

Washington, DC

$ 121,360

38,885

83,719

Costs Capitalized Subsequent to Acquisition

5,409

Land and Improvements

42,011

Buildings and Improvements

86,002

Land Held for Development

Development and Construction in Progress

Total

128,013

Accumulated Depreciation

$ 20,328

Year(s) Built / Renovation

2007

Depreciable Lives (Years)

-1

Kingstowne Towne Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Kingstowne Towne Center

Office

Alexandria, VA

$ 33,338

18,021

109,038

Costs Capitalized Subsequent to Acquisition

578

Land and Improvements

18,021

Buildings and Improvements

109,616

Land Held for Development

Development and Construction in Progress

Total

127,637

Accumulated Depreciation

$ 26,508

Year(s) Built / Renovation

2003-2006

Depreciable Lives (Years)

-1

1333 New Hampshire Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

1333 New Hampshire Avenue

Office

Washington, DC

$ 34,032

85,660

Costs Capitalized Subsequent to Acquisition

3,619

Land and Improvements

34,032

Buildings and Improvements

89,279

Land Held for Development

Development and Construction in Progress

Total

123,311

Accumulated Depreciation

$ 29,574

Year(s) Built / Renovation

1996

Depreciable Lives (Years)

-1

601 Massachusetts Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

601 Massachusetts Avenue

Type

Development

Location

Washington, DC

Costs Capitalized Subsequent to Acquisition

$ 121,694

Land and Improvements

Buildings and Improvements

Land Held for Development

Development and Construction in Progress

121,694

Total

121,694

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

535 Mission [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

535 Mission Street

Development

San Francisco, CA

Costs Capitalized Subsequent to Acquisition

113,274

Land and Improvements

Buildings and Improvements

Land Held for Development

Development and Construction in Progress

113,274

Total

113,274

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

1330 Connecticut Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

1330 Connecticut Avenue

Office

Washington, DC

$ 25,982

82,311

Costs Capitalized Subsequent to Acquisition

11,673

Land and Improvements

25,982

Buildings and Improvements

93,984

Land Held for Development

Development and Construction in Progress

Total

119,966

Accumulated Depreciation

$ 28,822

Year(s) Built / Renovation

1984

Depreciable Lives (Years)

-1

Weston Corporate Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Weston Corporate Center

Office

Weston, MA

$ 25,753

92,312

Costs Capitalized Subsequent to Acquisition

(123)

Land and Improvements

25,854

Buildings and Improvements

92,088

Land Held for Development

Development and Construction in Progress

Total

117,942

Accumulated Depreciation

$ 10,921

Year(s) Built / Renovation

2010

Depreciable Lives (Years)

-1

Capital Gallery [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Capital Gallery

Office

Washington, DC

4,725

29,565

Costs Capitalized Subsequent to Acquisition

76,862

Land and Improvements

6,128

Buildings and Improvements

105,024

Land Held for Development

Development and Construction in Progress

Total

111,152

Accumulated Depreciation

$ 48,693

Year(s) Built / Renovation

1981/2006

Depreciable Lives (Years)

^[2]

-1

One Freedom Square [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

One Freedom Square

Office

Reston, VA

$ 9,929

84,504

Costs Capitalized Subsequent to Acquisition

11,029

Land and Improvements

9,883

Buildings and Improvements

95,579

Land Held for Development

Development and Construction in Progress

Total

105,462

Accumulated Depreciation

$ 31,979

Year(s) Built / Renovation

2000

Depreciable Lives (Years)

^[2]

-1

One And Two Reston Overlook [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

One and Two Reston Overlook

Office

Reston, VA

$ 16,456

66,192

Costs Capitalized Subsequent to Acquisition

22,217

Land and Improvements

16,456

Buildings and Improvements

88,409

Land Held for Development

Development and Construction in Progress

Total

104,865

Accumulated Depreciation

$ 30,481

Year(s) Built / Renovation

1999

Depreciable Lives (Years)

^[2]

-1

Seven Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Seven Cambridge Center

Office

Cambridge, MA

$ 3,457

97,136

Costs Capitalized Subsequent to Acquisition

210

Land and Improvements

3,457

Buildings and Improvements

97,346

Land Held for Development

Development and Construction in Progress

Total

100,803

Accumulated Depreciation

$ 47,101

Year(s) Built / Renovation

2006

Depreciable Lives (Years)

^[2]

-1

Two Freedom Square [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Two Freedom Square

Office

Reston, VA

$ 13,930

77,739

Costs Capitalized Subsequent to Acquisition

7,604

Land and Improvements

13,866

Buildings and Improvements

85,407

Land Held for Development

Development and Construction in Progress

Total

99,273

Accumulated Depreciation

$ 36,361

Year(s) Built / Renovation

2001

Depreciable Lives (Years)

^[2]

-1

Discovery Square [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Discovery Square

Office

Reston, VA

$ 11,198

71,782

Costs Capitalized Subsequent to Acquisition

10,644

Land and Improvements

11,146

Buildings and Improvements

82,478

Land Held for Development

Development and Construction in Progress

Total

93,624

Accumulated Depreciation

$ 28,029

Year(s) Built / Renovation

2001

Depreciable Lives (Years)

^[2]

-1

140 Kendrick Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

140 Kendrick Street

Office

Needham, MA

$ 18,095

66,905

Costs Capitalized Subsequent to Acquisition

10,769

Land and Improvements

18,095

Buildings and Improvements

77,674

Land Held for Development

Development and Construction in Progress

Total

95,769

Accumulated Depreciation

$ 16,834

Year(s) Built / Renovation

2000

Depreciable Lives (Years)

^[2]

-1

Five Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Five Cambridge Center

Office

Cambridge, MA

$ 18,863

53,346

Costs Capitalized Subsequent to Acquisition

29,464

Land and Improvements

21,098

Buildings and Improvements

80,575

Land Held for Development

Development and Construction in Progress

Total

101,673

Accumulated Depreciation

$ 19,117

Year(s) Built / Renovation

1981/1996

Depreciable Lives (Years)

^[2]

-1

77 CityPoint [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

77 CityPoint

Office

Waltham, MA

$ 13,847

60,383

Costs Capitalized Subsequent to Acquisition

3,055

Land and Improvements

13,847

Buildings and Improvements

63,438

Land Held for Development

Development and Construction in Progress

Total

77,285

Accumulated Depreciation

$ 12,289

Year(s) Built / Renovation

2008

Depreciable Lives (Years)

^[2]

-1

North First Business Park [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

North First Business Park

Office

San Jose, CA

$ 58,402

13,069

Costs Capitalized Subsequent to Acquisition

3,987

Land and Improvements

23,371

Buildings and Improvements

16,198

Land Held for Development

35,889

Development and Construction in Progress

Total

75,458

Accumulated Depreciation

$ 10,208

Year(s) Built / Renovation

1981

Depreciable Lives (Years)

^[2]

-1

Four Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Four Cambridge Center

Office

Cambridge, MA

$ 19,104

52,078

Costs Capitalized Subsequent to Acquisition

11,693

Land and Improvements

20,741

Buildings and Improvements

62,134

Land Held for Development

Development and Construction in Progress

Total

82,875

Accumulated Depreciation

$ 10,739

Year(s) Built / Renovation

1983/1998

Depreciable Lives (Years)

^[2]

-1

230 CityPoint [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

230 CityPoint

Office

Waltham, MA

$ 13,189

49,823

Costs Capitalized Subsequent to Acquisition

11,485

Land and Improvements

13,189

Buildings and Improvements

61,308

Land Held for Development

Development and Construction in Progress

Total

74,497

Accumulated Depreciation

$ 17,363

Year(s) Built / Renovation

1992

Depreciable Lives (Years)

^[2]

-1

Waltham Weston Corporate Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Waltham Weston Corporate Center

Office

Waltham, MA

$ 10,385

60,694

Costs Capitalized Subsequent to Acquisition

5,475

Land and Improvements

10,350

Buildings and Improvements

66,204

Land Held for Development

Development and Construction in Progress

Total

76,554

Accumulated Depreciation

$ 21,259

Year(s) Built / Renovation

2003

Depreciable Lives (Years)

^[2]

-1

2440 West El Camino Real [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

2440 West El Camino Real

Office

Mountain View, CA

$ 16,741

51,285

Costs Capitalized Subsequent to Acquisition

502

Land and Improvements

16,741

Buildings and Improvements

51,787

Land Held for Development

Development and Construction in Progress

Total

68,528

Accumulated Depreciation

$ 4,390

Year(s) Built / Renovation

1987/2003

Depreciable Lives (Years)

^[2]

-1

Wisconsin Place [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Wisconsin Place

Office

Chevy Chase, MD

53,349

Costs Capitalized Subsequent to Acquisition

12,787

Land and Improvements

Buildings and Improvements

66,136

Land Held for Development

Development and Construction in Progress

Total

66,136

Accumulated Depreciation

$ 11,573

Year(s) Built / Renovation

2009

Depreciable Lives (Years)

^[2]

-1

Reston Corporate Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Reston Corporate Center

Office

Reston, VA

$ 9,135

50,857

Costs Capitalized Subsequent to Acquisition

2,735

Land and Improvements

9,496

Buildings and Improvements

53,231

Land Held for Development

Development and Construction in Progress

Total

62,727

Accumulated Depreciation

$ 20,642

Year(s) Built / Renovation

1984

Depreciable Lives (Years)

^[2]

-1

New Dominion Technology Park, Bldg. Two [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

New Dominion Technology Park, Bldg. Two

Office

Herndon, VA

$ 63,000

5,584

51,868

Costs Capitalized Subsequent to Acquisition

149

Land and Improvements

5,574

Buildings and Improvements

52,027

Land Held for Development

Development and Construction in Progress

Total

57,601

Accumulated Depreciation

$ 15,990

Year(s) Built / Renovation

2004

Depreciable Lives (Years)

^[2]

-1

Sumner Square [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Sumner Square

Office

Washington, DC

$ 624

28,745

Costs Capitalized Subsequent to Acquisition

21,599

Land and Improvements

958

Buildings and Improvements

50,010

Land Held for Development

Development and Construction in Progress

Total

50,968

Accumulated Depreciation

$ 22,971

Year(s) Built / Renovation

1985

Depreciable Lives (Years)

^[2]

-1

New Dominion Technology Park, Bldg. One [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

New Dominion Technology Park, Bldg. One

Office

Herndon, VA

$ 43,278

3,880

43,227

Costs Capitalized Subsequent to Acquisition

1,072

Land and Improvements

3,880

Buildings and Improvements

44,299

Land Held for Development

Development and Construction in Progress

Total

48,179

Accumulated Depreciation

$ 19,160

Year(s) Built / Renovation

2001

Depreciable Lives (Years)

^[2]

-1

191 Spring Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

191 Spring Street

Office

Lexington, MA

$ 2,850

27,166

Costs Capitalized Subsequent to Acquisition

17,359

Land and Improvements

2,850

Buildings and Improvements

44,525

Land Held for Development

Development and Construction in Progress

Total

47,375

Accumulated Depreciation

$ 29,454

Year(s) Built / Renovation

1971/1995

Depreciable Lives (Years)

^[2]

-1

200 West Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

200 West Street

Office

Waltham, MA

$ 16,148

24,983

Costs Capitalized Subsequent to Acquisition

5,907

Land and Improvements

16,148

Buildings and Improvements

30,890

Land Held for Development

Development and Construction in Progress

Total

47,038

Accumulated Depreciation

$ 14,432

Year(s) Built / Renovation

1999

Depreciable Lives (Years)

^[2]

-1

University Place [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

University Place

Office

Cambridge, MA

$ 13,692

37,091

Costs Capitalized Subsequent to Acquisition

5,335

Land and Improvements

Buildings and Improvements

42,399

Land Held for Development

Development and Construction in Progress

Total

42,426

Accumulated Depreciation

$ 20,476

Year(s) Built / Renovation

1985

Depreciable Lives (Years)

^[2]

-1

2600 Tower Oaks Boulevard [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

2600 Tower Oaks Boulevard

Office

Rockville, MD

$ 4,243

31,125

Costs Capitalized Subsequent to Acquisition

6,094

Land and Improvements

4,244

Buildings and Improvements

37,218

Land Held for Development

Development and Construction in Progress

Total

41,462

Accumulated Depreciation

$ 16,249

Year(s) Built / Renovation

2001

Depreciable Lives (Years)

^[2]

-1

Quorum Office Park [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Quorum Office Park

Office

Chelmsford, MA

$ 3,750

32,454

Costs Capitalized Subsequent to Acquisition

3,974

Land and Improvements

4,762

Buildings and Improvements

35,416

Land Held for Development

Development and Construction in Progress

Total

40,178

Accumulated Depreciation

$ 12,493

Year(s) Built / Renovation

2001

Depreciable Lives (Years)

^[2]

-1

One Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

One Cambridge Center

Office

Cambridge, MA

$ 134

25,110

Costs Capitalized Subsequent to Acquisition

18,952

Land and Improvements

134

Buildings and Improvements

44,062

Land Held for Development

Development and Construction in Progress

Total

44,196

Accumulated Depreciation

$ 24,666

Year(s) Built / Renovation

1987

Depreciable Lives (Years)

^[2]

-1

Three Patriots Park [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Three Patriots Park

Office

Reston, VA

$ 3,594

32,977

Costs Capitalized Subsequent to Acquisition

1,353

Land and Improvements

3,594

Buildings and Improvements

34,330

Land Held for Development

Development and Construction in Progress

Total

37,924

Accumulated Depreciation

$ 12,217

Year(s) Built / Renovation

2006

Depreciable Lives (Years)

^[2]

-1

Mountain View Technology [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Mountain View Technology Park

Office

Mountain View, CA

$ 20,359

13,640

Costs Capitalized Subsequent to Acquisition

182

Land and Improvements

20,359

Buildings and Improvements

13,822

Land Held for Development

Development and Construction in Progress

Total

34,181

Accumulated Depreciation

$ 761

Year(s) Built / Renovation

1972

Depreciable Lives (Years)

^[2]

-1

Eight Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Eight Cambridge Center

Office

Cambridge, MA

$ 850

25,042

Costs Capitalized Subsequent to Acquisition

6,502

Land and Improvements

822

Buildings and Improvements

31,572

Land Held for Development

Development and Construction in Progress

Total

32,394

Accumulated Depreciation

$ 10,835

Year(s) Built / Renovation

1999

Depreciable Lives (Years)

^[2]

-1

500 E Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

500 E Street

Office

Washington, DC

$ 109

22,420

Costs Capitalized Subsequent to Acquisition

9,614

Land and Improvements

1,569

Buildings and Improvements

30,574

Land Held for Development

Development and Construction in Progress

Total

32,143

Accumulated Depreciation

$ 20,147

Year(s) Built / Renovation

1987

Depreciable Lives (Years)

^[2]

-1

Ten Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Ten Cambridge Center

Office

Cambridge, MA

$ 1,299

12,943

Costs Capitalized Subsequent to Acquisition

4,011

Land and Improvements

1,868

Buildings and Improvements

16,385

Land Held for Development

Development and Construction in Progress

Total

18,253

Accumulated Depreciation

$ 11,019

Year(s) Built / Renovation

1990

Depreciable Lives (Years)

^[2]

-1

Three Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Three Cambridge Center

Office

Cambridge, MA

$ 174

12,200

Costs Capitalized Subsequent to Acquisition

7,987

Land and Improvements

772

Buildings and Improvements

19,589

Land Held for Development

Development and Construction in Progress

Total

20,361

Accumulated Depreciation

$ 9,651

Year(s) Built / Renovation

1987

Depreciable Lives (Years)

^[2]

-1

40 Shattuck Road [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

40 Shattuck Road

Office

Andover, MA

$ 709

14,740

Costs Capitalized Subsequent to Acquisition

1,717

Land and Improvements

709

Buildings and Improvements

16,457

Land Held for Development

Development and Construction in Progress

Total

17,166

Accumulated Depreciation

$ 5,436

Year(s) Built / Renovation

2001

Depreciable Lives (Years)

^[2]

-1

201 Spring Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

201 Spring Street

Office

Lexington, MA

$ 2,849

15,303

Costs Capitalized Subsequent to Acquisition

(1,253)

Land and Improvements

2,849

Buildings and Improvements

14,050

Land Held for Development

Development and Construction in Progress

Total

16,899

Accumulated Depreciation

$ 5,868

Year(s) Built / Renovation

1997

Depreciable Lives (Years)

^[2]

-1

Lexington Office Park [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Lexington Office Park

Office

Lexington, MA

$ 998

1,426

Costs Capitalized Subsequent to Acquisition

12,998

Land and Improvements

1,073

Buildings and Improvements

14,349

Land Held for Development

Development and Construction in Progress

Total

15,422

Accumulated Depreciation

$ 10,453

Year(s) Built / Renovation

1982

Depreciable Lives (Years)

^[2]

-1

6601 and 6605 Springfield Center Drive [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

6601 & 6605 Springfield Center Drive

Land

Springfield, VA

Costs Capitalized Subsequent to Acquisition

13,866

Land and Improvements

Buildings and Improvements

Land Held for Development

13,866

Development and Construction in Progress

Total

13,866

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

^[2]

N/A

92 - 100 Hayden Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

92-100 Hayden Avenue

Office

Lexington, MA

$ 594

6,748

Costs Capitalized Subsequent to Acquisition

7,090

Land and Improvements

619

Buildings and Improvements

13,813

Land Held for Development

Development and Construction in Progress

Total

14,432

Accumulated Depreciation

$ 9,804

Year(s) Built / Renovation

1985

Depreciable Lives (Years)

^[2]

-1

181 Spring Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

181 Spring Street

Office

Lexington, MA

$ 1,066

9,520

Costs Capitalized Subsequent to Acquisition

1,573

Land and Improvements

1,066

Buildings and Improvements

11,093

Land Held for Development

Development and Construction in Progress

Total

12,159

Accumulated Depreciation

$ 3,950

Year(s) Built / Renovation

1999

Depreciable Lives (Years)

^[2]

-1

Waltham Office Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Waltham Office Center

Land

Waltham, MA

Costs Capitalized Subsequent to Acquisition

12,069

Land and Improvements

Buildings and Improvements

7,963

Land Held for Development

4,106

Development and Construction in Progress

Total

12,069

Accumulated Depreciation

$ 7,967

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

^[2]

N/A

195 West Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

195 West Street

Office

Waltham, MA

$ 1,611

6,652

Costs Capitalized Subsequent to Acquisition

3,186

Land and Improvements

1,611

Buildings and Improvements

9,838

Land Held for Development

Development and Construction in Progress

Total

11,449

Accumulated Depreciation

$ 6,036

Year(s) Built / Renovation

1990

Depreciable Lives (Years)

^[2]

-1

91 Hartwell Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

91 Hartwell Avenue

Office

Lexington, MA

$ 784

6,464

Costs Capitalized Subsequent to Acquisition

4,357

Land and Improvements

784

Buildings and Improvements

10,821

Land Held for Development

Development and Construction in Progress

Total

11,605

Accumulated Depreciation

$ 7,439

Year(s) Built / Renovation

1985

Depreciable Lives (Years)

^[2]

-1

7501 Boston Boulevard, Building Seven [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7501 Boston Boulevard, Building Seven

Office

Springfield, VA

$ 665

9,273

Costs Capitalized Subsequent to Acquisition

Land and Improvements

665

Buildings and Improvements

9,312

Land Held for Development

Development and Construction in Progress

Total

9,977

Accumulated Depreciation

$ 3,819

Year(s) Built / Renovation

1997

Depreciable Lives (Years)

^[2]

-1

Eleven Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Eleven Cambridge Center

Office

Cambridge, MA

$ 121

5,535

Costs Capitalized Subsequent to Acquisition

4,318

Land and Improvements

121

Buildings and Improvements

9,853

Land Held for Development

Development and Construction in Progress

Total

9,974

Accumulated Depreciation

$ 7,119

Year(s) Built / Renovation

1984

Depreciable Lives (Years)

^[2]

-1

33 Hayden Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

33 Hayden Avenue

Office

Lexington, MA

$ 266

3,234

Costs Capitalized Subsequent to Acquisition

9,646

Land and Improvements

266

Buildings and Improvements

12,880

Land Held for Development

Development and Construction in Progress

Total

13,146

Accumulated Depreciation

$ 7,390

Year(s) Built / Renovation

1979

Depreciable Lives (Years)

^[2]

-1

7435 Boston Boulevard, Building One [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7435 Boston Boulevard, Building One

Office

Springfield, VA

$ 392

3,822

Costs Capitalized Subsequent to Acquisition

3,202

Land and Improvements

486

Buildings and Improvements

6,930

Land Held for Development

Development and Construction in Progress

Total

7,416

Accumulated Depreciation

$ 5,422

Year(s) Built / Renovation

1982

Depreciable Lives (Years)

^[2]

-1

7450 Boston Boulevard, Building Three [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7450 Boston Boulevard, Building Three

Office

Springfield, VA

$ 1,165

4,681

Costs Capitalized Subsequent to Acquisition

1,501

Land and Improvements

1,327

Buildings and Improvements

6,020

Land Held for Development

Development and Construction in Progress

Total

7,347

Accumulated Depreciation

$ 2,852

Year(s) Built / Renovation

1987

Depreciable Lives (Years)

^[2]

-1

8000 Grainger Court, Building Five [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

8000 Grainger Court, Building Five

Office

Springfield, VA

$ 366

4,282

Costs Capitalized Subsequent to Acquisition

2,350

Land and Improvements

453

Buildings and Improvements

6,545

Land Held for Development

Development and Construction in Progress

Total

6,998

Accumulated Depreciation

$ 5,071

Year(s) Built / Renovation

1984

Depreciable Lives (Years)

^[2]

-1

453 Ravendale Drive [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

453 Ravendale Drive

Office

Mountain View, CA

$ 0

5,477

1,090

Costs Capitalized Subsequent to Acquisition

230

Land and Improvements

5,477

Buildings and Improvements

1,320

Land Held for Development

Development and Construction in Progress

Total

6,797

Accumulated Depreciation

$ 142

Year(s) Built / Renovation

1977

Depreciable Lives (Years)

^[2]

-1

7500 Boston Boulevard, Building Six [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7500 Boston Boulevard, Building Six

Office

Springfield, VA

$ 138

3,749

Costs Capitalized Subsequent to Acquisition

2,057

Land and Improvements

273

Buildings and Improvements

5,671

Land Held for Development

Development and Construction in Progress

Total

5,944

Accumulated Depreciation

$ 4,053

Year(s) Built / Renovation

1985

Depreciable Lives (Years)

^[2]

-1

7300 Boston Boulevard, Building Thirteen [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7300 Boston Boulevard, Building Thirteen

Office

Springfield, VA

$ 608

4,773

Costs Capitalized Subsequent to Acquisition

Land and Improvements

608

Buildings and Improvements

4,791

Land Held for Development

Development and Construction in Progress

Total

5,399

Accumulated Depreciation

$ 3,902

Year(s) Built / Renovation

2002

Depreciable Lives (Years)

^[2]

-1

7601 Boston Boulevard, Building Eight [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7601 Boston Boulevard, Building Eight

Office

Springfield, VA

$ 200

878

Costs Capitalized Subsequent to Acquisition

4,182

Land and Improvements

378

Buildings and Improvements

4,882

Land Held for Development

Development and Construction in Progress

Total

5,260

Accumulated Depreciation

$ 3,472

Year(s) Built / Renovation

1986

Depreciable Lives (Years)

^[2]

-1

Fourteen Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Fourteen Cambridge Center

Office

Cambridge, MA

$ 110

4,483

Costs Capitalized Subsequent to Acquisition

569

Land and Improvements

110

Buildings and Improvements

5,052

Land Held for Development

Development and Construction in Progress

Total

5,162

Accumulated Depreciation

$ 3,709

Year(s) Built / Renovation

1983

Depreciable Lives (Years)

^[2]

-1

8000 Corporate Court, Building Eleven [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

8000 Corporate Court, Building Eleven

Office

Springfield, VA

$ 136

3,071

Costs Capitalized Subsequent to Acquisition

1,133

Land and Improvements

687

Buildings and Improvements

3,653

Land Held for Development

Development and Construction in Progress

Total

4,340

Accumulated Depreciation

$ 2,300

Year(s) Built / Renovation

1989

Depreciable Lives (Years)

^[2]

-1

7375 Boston Boulevard, Building Ten [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7375 Boston Boulevard, Building Ten

Office

Springfield, VA

$ 23

2,685

Costs Capitalized Subsequent to Acquisition

826

Land and Improvements

Buildings and Improvements

3,487

Land Held for Development

Development and Construction in Progress

Total

3,534

Accumulated Depreciation

$ 2,235

Year(s) Built / Renovation

1988

Depreciable Lives (Years)

^[2]

-1

7374 Boston Boulevard, Building Four [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7374 Boston Boulevard, Building Four

Office

Springfield, VA

$ 241

1,605

Costs Capitalized Subsequent to Acquisition

1,519

Land and Improvements

303

Buildings and Improvements

3,062

Land Held for Development

Development and Construction in Progress

Total

3,365

Accumulated Depreciation

$ 2,271

Year(s) Built / Renovation

1984

Depreciable Lives (Years)

^[2]

-1

7451 Boston Boulevard, Building Two [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

7451 Boston Boulevard, Building Two

Office

Springfield, VA

$ 249

1,542

Costs Capitalized Subsequent to Acquisition

1,000

Land and Improvements

535

Buildings and Improvements

2,256

Land Held for Development

Development and Construction in Progress

Total

2,791

Accumulated Depreciation

$ 2,083

Year(s) Built / Renovation

1982

Depreciable Lives (Years)

^[2]

-1

164 Lexington Road [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

164 Lexington Road

Office

Billerica, MA

$ 592

1,370

Costs Capitalized Subsequent to Acquisition

117

Land and Improvements

592

Buildings and Improvements

1,487

Land Held for Development

Development and Construction in Progress

Total

2,079

Accumulated Depreciation

$ 670

Year(s) Built / Renovation

1982

Depreciable Lives (Years)

^[2]

-1

32 Hartwell Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

32 Hartwell Avenue

Office

Lexington, MA

$ 168

1,943

Costs Capitalized Subsequent to Acquisition

214

Land and Improvements

168

Buildings and Improvements

2,157

Land Held for Development

Development and Construction in Progress

Total

2,325

Accumulated Depreciation

$ 1,478

Year(s) Built / Renovation

1968-1979/1987

Depreciable Lives (Years)

^[2]

-1

Seventeen Hartwell Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

17 Hartwell Avenue

Office

Lexington, MA

$ 26

150

Costs Capitalized Subsequent to Acquisition

845

Land and Improvements

Buildings and Improvements

995

Land Held for Development

Development and Construction in Progress

Total

1,021

Accumulated Depreciation

$ 615

Year(s) Built / Renovation

1968

Depreciable Lives (Years)

^[2]

-1

Residences on The Avenue, 2221 I St., NW [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Residences on The Avenue, 2221 I St., NW

Residential

Washington, DC

119,874

Costs Capitalized Subsequent to Acquisition

(32)

Land and Improvements

Buildings and Improvements

119,842

Land Held for Development

Development and Construction in Progress

Total

119,842

Accumulated Depreciation

$ 7,948

Year(s) Built / Renovation

2011

Depreciable Lives (Years)

^[2]

-1

The Lofts At Atlantic Wharf [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

The Lofts at Atlantic Wharf

Residential

Boston, MA

$ 3,529

54,891

Costs Capitalized Subsequent to Acquisition

1,543

Land and Improvements

3,529

Buildings and Improvements

56,434

Land Held for Development

Development and Construction in Progress

Total

59,963

Accumulated Depreciation

$ 3,591

Year(s) Built / Renovation

2011

Depreciable Lives (Years)

^[2]

-1

Cambridge Center East Garage [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Cambridge Center East Garage

Garage

Cambridge, MA

35,035

Costs Capitalized Subsequent to Acquisition

1,073

Land and Improvements

Buildings and Improvements

36,108

Land Held for Development

Development and Construction in Progress

Total

36,108

Accumulated Depreciation

$ 6,624

Year(s) Built / Renovation

1984

Depreciable Lives (Years)

^[2]

-1

Cambridge Center West Garage [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Cambridge Center West Garage

Garage

Cambridge, MA

$ 1,256

15,697

Costs Capitalized Subsequent to Acquisition

841

Land and Improvements

1,256

Buildings and Improvements

16,538

Land Held for Development

Development and Construction in Progress

Total

17,794

Accumulated Depreciation

$ 3,262

Year(s) Built / Renovation

2006

Depreciable Lives (Years)

^[2]

-1

Cambridge Center Marriott [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Cambridge Center Marriott

Hotel

Cambridge, MA

$ 478

37,918

Costs Capitalized Subsequent to Acquisition

33,090

Land and Improvements

478

Buildings and Improvements

71,008

Land Held for Development

Development and Construction in Progress

Total

71,486

Accumulated Depreciation

$ 46,750

Year(s) Built / Renovation

1986

Depreciable Lives (Years)

^[2]

-1

Cambridge Center North Garage [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Cambridge Center North Garage

Garage

Cambridge, MA

$ 1,163

11,633

Costs Capitalized Subsequent to Acquisition

1,085

Land and Improvements

1,163

Buildings and Improvements

12,718

Land Held for Development

Development and Construction in Progress

Total

13,881

Accumulated Depreciation

$ 7,909

Year(s) Built / Renovation

1990

Depreciable Lives (Years)

^[2]

-1

250 West 55th Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

250 West 55th Street

Development

New York, NY

Costs Capitalized Subsequent to Acquisition

816,578

Land and Improvements

15,889

Buildings and Improvements

44,227

Land Held for Development

Development and Construction in Progress

756,462

Total

816,578

Accumulated Depreciation

$ 483

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Transbay Tower [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Transbay Tower

Development

San Francisco, CA

Costs Capitalized Subsequent to Acquisition

255,406

Land and Improvements

Buildings and Improvements

Land Held for Development

Development and Construction in Progress

255,406

Total

255,406

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

680 Folsom Street [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

680 Folsom Street

Development

San Francisco, CA

$ 0

Costs Capitalized Subsequent to Acquisition

241,093

Land and Improvements

Buildings and Improvements

Land Held for Development

3,475

Development and Construction in Progress

237,618

Total

241,093

Accumulated Depreciation

$ 0

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

The Avant at Reston Town Center Residential [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

The Avant at Reston Town Center Residential

Development

Reston, VA

Costs Capitalized Subsequent to Acquisition

107,022

Land and Improvements

12,741

Buildings and Improvements

55,701

Land Held for Development

Development and Construction in Progress

38,580

Total

107,022

Accumulated Depreciation

$ 160

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Seventeen Cambridge Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Seventeen Cambridge Center

Office

Cambridge, MA

$ 18,080

51,262

Costs Capitalized Subsequent to Acquisition

Land and Improvements

18,080

Buildings and Improvements

51,262

Land Held for Development

Development and Construction in Progress

Total

69,342

Accumulated Depreciation

$ 1,080

Year(s) Built / Renovation

2013

Depreciable Lives (Years)

(1)

Plaza at Almaden [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Plaza at Almaden

Land

San Jose, CA

Costs Capitalized Subsequent to Acquisition

29,003

Land and Improvements

Buildings and Improvements

Land Held for Development

29,003

Development and Construction in Progress

Total

29,003

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Springfield Metro Center [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Springfield Metro Center

Land

Springfield, VA

Costs Capitalized Subsequent to Acquisition

32,073

Land and Improvements

Buildings and Improvements

Land Held for Development

32,073

Development and Construction in Progress

Total

32,073

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Tower Oaks Master Plan [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Tower Oaks Master Plan

Land

Rockville, MD

Costs Capitalized Subsequent to Acquisition

28,976

Land and Improvements

Buildings and Improvements

Land Held for Development

28,976

Development and Construction in Progress

Total

28,976

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Reston Signature Site [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Reston Signature Site

Land

Reston, VA

Costs Capitalized Subsequent to Acquisition

27,890

Land and Improvements

Buildings and Improvements

Land Held for Development

27,890

Development and Construction in Progress

Total

27,890

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Prospect Hill [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Prospect Hill

Land

Waltham, MA

Costs Capitalized Subsequent to Acquisition

24,197

Land and Improvements

Buildings and Improvements

667

Land Held for Development

23,530

Development and Construction in Progress

Total

24,197

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Washingtonian North [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Washingtonian North

Land

Gaithersburg, MD

Costs Capitalized Subsequent to Acquisition

18,290

Land and Improvements

Buildings and Improvements

Land Held for Development

18,290

Development and Construction in Progress

Total

18,290

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

103 4th Avenue [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

103 4th Avenue

Land

Waltham, MA

Costs Capitalized Subsequent to Acquisition

11,918

Land and Improvements

Buildings and Improvements

Land Held for Development

11,918

Development and Construction in Progress

Total

11,918

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Cambridge Master Plan [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Cambridge Master Plan

Land

Cambridge, MA

Costs Capitalized Subsequent to Acquisition

11,153

Land and Improvements

Buildings and Improvements

Land Held for Development

11,153

Development and Construction in Progress

Total

11,153

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Reston Gateway [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Reston Gateway

Land

Reston, VA

Costs Capitalized Subsequent to Acquisition

9,682

Land and Improvements

Buildings and Improvements

Land Held for Development

9,682

Development and Construction in Progress

Total

9,682

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Reston Eastgate [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Reston Eastgate

Land

Reston, VA

Costs Capitalized Subsequent to Acquisition

8,807

Land and Improvements

Buildings and Improvements

Land Held for Development

8,807

Development and Construction in Progress

Total

8,807

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Crane Meadow [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Crane Meadow

Land

Marlborough, MA

Costs Capitalized Subsequent to Acquisition

8,725

Land and Improvements

Buildings and Improvements

Land Held for Development

8,725

Development and Construction in Progress

Total

8,725

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Broad Run Business Park [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

Broad Run Business Park

Land

Loudon County, VA

Costs Capitalized Subsequent to Acquisition

7,888

Land and Improvements

1,621

Buildings and Improvements

Land Held for Development

6,267

Development and Construction in Progress

Total

7,888

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

30 Shattuck Road [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate And Accumulated Depreciation Name of Property

30 Shattuck Road

Land

Andover, MA

Costs Capitalized Subsequent to Acquisition

1,212

Land and Improvements

Buildings and Improvements

Land Held for Development

1,212

Development and Construction in Progress

Total

1,212

Accumulated Depreciation

Year(s) Built / Renovation

N/A

Depreciable Lives (Years)

N/A

Minimum [Member]

Real Estate and Accumulated Depreciation [Line Items]

Real Estate and Accumulated Depreiation Life used for Depreciation

life of the lease

[1]	Includes the unamortized balance of the historical fair value adjustment totaling approximately $191.2 million.
[2]	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.

Real Estate and Accumulated Depreciation Activity of Real Estate and Accumulated Depreciation (details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Real Estate, Balance at the beginning of the year	$ 14,431,521	$ 12,922,967	$ 12,300,746
Real Estate, Additions to / improvements of real estate	4,410,622	1,602,583	668,084
Real Estate, Assets sold / written off	(318,866)	(94,029)	(45,863)
Real Estate, Balance at the end of the year	18,523,277	14,431,521	12,922,967
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Accumulated depreciation, Balance at the beginning of the year	2,862,302	2,577,118	2,267,682
Accumulated Depreciation, Depreciation expense	411,860	359,442	354,413
Accumulated Depreciation Assets sold / written off	(193,122)	(74,258)	(44,977)
Accumulated depreciation, Balance at the end of the year	$ 3,081,040	$ 2,862,302	$ 2,577,118

Label	Element	Value
Unconsolidated Joint Ventures [Member]
Secured Debt	us-gaap_SecuredDebt	$ 3,039,922,000
Secured Debt	us-gaap_SecuredDebt	$ 749,732,000