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Document And Entity Information	3 Months Ended
Document And Entity Information	Mar. 31, 2012 shares
Document And Entity Information [Abstract]
Document Type	10-Q
Document Period End Date	Mar. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1
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

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2012	Dec. 31, 2011
ASSETS
Real estate, at cost	$ 12,501,528	$ 11,867,724
Construction in progress	870,006	818,685
Land held for future development	264,125	262,917
Less: accumulated depreciation	(2,671,417)	(2,593,780)
Total real estate	10,964,242	10,355,546
Cash and cash equivalents	591,196	1,823,208
Cash held in escrows	30,697	40,332
Investments in securities	11,193	9,548
Tenant and other receivables (net of allowance for doubtful accounts of $1,370 and $1,766, respectively)	68,275	79,838
Related party notes receivable	281,177	280,442
Interest receivable from related party notes receivable	95,126	89,854
Accrued rental income (net of allowance of $2,631 and $2,515, respectively)	541,153	522,675
Deferred charges, net	500,957	445,403
Prepaid expenses and other assets	73,132	75,458
Investments in unconsolidated joint ventures	667,377	669,722
Total assets	13,824,525	14,392,026
Liabilities:
Mortgage notes payable	2,946,760	3,123,267
Unsecured senior notes (net of discount of $9,631 and $9,814, respectively)	3,865,369	3,865,186
Unsecured exchangeable senior notes (net of discount of $2,720 and $3,462, respectively)	1,148,497	1,715,685
Unsecured line of credit
Accounts payable and accrued expenses	165,441	155,139
Distributions payable	92,615	91,901
Accrued interest payable	97,997	69,105
Other liabilities	324,826	293,515
Total liabilities	8,641,505	9,313,798
Commitments and contingencies
Noncontrolling interests:
Redeemable partnership units-1,030,748 and 1,113,044 preferred units outstanding (1,352,688 and 1,460,688 common units at redemption value, if converted) at March 31, 2012 and December 31, 2011, respectively	142,019	145,484
Redeemable partnership units-16,527,994 and 16,562,838 common units and 1,690,649 and 1,601,004 long term incentive units outstanding at redemption value at March 31, 2012 and December 31, 2011, respectively	1,912,775	1,809,119
Capital:
Boston Properties Limited Partnership partners' capital-1,676,030 and 1,662,715 general partner units and 147,708,311 and 146,444,896 limited partner units outstanding at March 31, 2012 and December 31, 2011, respectively	3,129,493	3,124,688
Noncontrolling interests in property partnerships	(1,267)	(1,063)
Total capital	3,128,226	3,123,625
Total liabilities and capital	$ 13,824,525	$ 14,392,026

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Tenant and other receivables, allowance for doubtful accounts	$ 1,370	$ 1,766
Accrued rental income, allowance	2,631	2,515
Unsecured senior notes, discount	9,631	9,814
Unsecured exchangeable senior notes, discount	$ 2,720	$ 3,462
Redeemable partnership units, preferred units outstanding	1,030,748	1,113,044
Redeemable partnership units, common units at redemption value, if converted	1,352,688	1,460,688
Redeemable partnership units, common units	16,527,994	16,562,838
Redeemable partnership units, long term incentive units outstanding at redemption value	1,690,649	1,601,004
General Partners' Capital Account, Units Outstanding	1,676,030	1,662,715
Limited Partners' Capital Account, Units Outstanding	147,708,311	146,444,896

Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Revenue
Base rent	$ 357,701	$ 338,925
Recoveries from tenants	52,568	45,849
Parking and other	22,428	19,064
Total rental revenue	432,697	403,838
Hotel revenue	6,816	5,948
Development and management services	8,149	7,428
Total revenue	447,662	417,214
Expenses
Rental	157,506	139,630
Hotel	6,099	5,739
General and administrative	27,619	24,643
Transaction costs	2,104	72
Depreciation and amortization	107,619	107,182
Total expenses	300,947	277,266
Operating income	146,715	139,948
Other income (expense)
Income from unconsolidated joint ventures	11,721	7,976
Interest and other income	1,646	974
Gains from investments in securities	801	373
Gains from early extinguishments of debt	767
Interest expense	(103,237)	(98,525)
Income from continuing operations	58,413	50,746
Discontinued operations
Loss from discontinued operations	(156)	(497)
Gain on forgiveness of debt from discontinued operations	18,361
Net income	76,618	50,249
Net income attributable to noncontrolling interests
Noncontrolling interests in property partnership	(546)	(529)
Noncontrolling interest - redeemable preferred units	(801)	(823)
Net income attributable to Boston Properties, Limited Partnership	$ 75,271	$ 48,897
Basic earnings per common unit attributable to Boston Properties Limited Partnership
Income from continuing operations	$ 0.34	$ 0.30
Discontinued operations	0.11	0.00
Net income	$ 0.45	$ 0.30
Weighted average number of common units outstanding	166,060	162,082
Diluted earnings per common unit attributable to Boston Properties Limited Partnership
Income from continuing operations	$ 0.34	$ 0.30
Discontinued operations	0.11
Net income	$ 0.45	$ 0.30
Weighted average number of common and common equivalent units outstanding	166,463	162,491

Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 76,618	$ 50,249
Other comprehensive income:
Amortization of interest rate contracts	649	649
Other comprehensive income	649	649
Comprehensive income	77,267	50,898
Comprehensive income attributable to noncontrolling interests	(1,347)	(1,352)
Comprehensive income attributable to Boston Properties Limited Partnership	$ 75,920	$ 49,546

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References

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+ Details

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to noncontrolling interests, if any. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References + Details

- Definition

This element represents Other Comprehensive Income or Loss, Net of Tax, for the period attributable to the parent entity. Includes deferred gains or losses on qualifying hedges, unrealized holding gains or losses on available-for-sale securities, minimum pension liability, and cumulative translation adjustment.

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- Definition

Net of tax effect of the reclassification adjustment for accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges included in accumulated comprehensive income that was realized in net income during the period.

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- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Consolidated Statements Of Partners' Capital $ in Thousands	USD ($)
Partners' Capital, Beginning Balance at Dec. 31, 2010	$ 2,693,939
Statement of Partners' Capital [Abstract]
Contributions	350,077
Net income allocable to general and limited partner units	42,868
Distributions	(72,529)
Accumulated other comprehensive loss	569
Unearned compensation	1,031
Conversion of redeemable partnership units	29,216
Adjustment to reflect redeemable partnership units at redemption value	(136,982)
Partners' Capital, Ending Balance at Mar. 31, 2011	2,908,189
Partners' Capital, Beginning Balance at Dec. 31, 2011	3,124,688
Statement of Partners' Capital [Abstract]
Contributions	111,639
Net income allocable to general and limited partner units	67,240
Distributions	(82,161)
Accumulated other comprehensive loss	580
Unearned compensation	76
Conversion of redeemable partnership units	6,026
Adjustment to reflect redeemable partnership units at redemption value	(98,595)
Partners' Capital, Ending Balance at Mar. 31, 2012	$ 3,129,493

- Definition

The amount of ownership interest of different classes of partners in limited partnership.

+ References + Details

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net income	$ 76,618	$ 50,249
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	107,683	107,373
Non-cash compensation expense	11,358	11,856
Income from unconsolidated joint ventures	(11,721)	(7,976)
Distributions of net cash flow from operations of unconsolidated joint ventures	8,972	7,663
Gains from investments in securities	(801)	(373)
Non-cash portion of interest expense	11,839	13,434
Settlement of accreted debt discount on repurchases of unsecured exchangeable senior notes	(68,760)
Gains from early extinguishments of debt	(914)
Gain on forgiveness of debt from discontinued operations	(18,361)
Change in assets and liabilities:
Cash held in escrows	9,359	(7,661)
Tenant and other receivables, net	22,686	6,073
Accrued rental income, net	(19,266)	(20,434)
Prepaid expenses and other assets	6,983	(29,432)
Accounts payable and accrued expenses	1,563	(9,134)
Accrued interest payable	31,073	25,743
Other liabilities	8,883	(5,940)
Tenant leasing costs	(7,933)	(9,157)
Total adjustments	92,643	82,035
Net cash provided by operating activities	169,261	132,284
Cash flows from investing activities:
Acquisitions of real estate	(621,359)	(41,100)
Construction in progress	(93,657)	(64,877)
Building and other capital improvements	(8,613)	(8,874)
Tenant improvements	(34,912)	(14,251)
Deposit on real estate released from escrow		10,000
Issuance of notes receivable	(735)
Capital contributions to unconsolidated joint ventures	(47)	(1,232)
Capital distributions from unconsolidated joint ventures	57
Investments in securities, net	(844)	(695)
Net cash used in investing activities	(760,110)	(121,029)
Cash flows from financing activities:
Repayments of mortgage notes payable	(150,519)	(8,777)
Redemption/Repurchase of unsecured exchangeable senior notes	(507,434)
Deferred financing costs	(91)	(676)
Net proceeds from ATM stock issuances	109,330	345,369
Net proceeds from equity transactions	613	3,128
Distributions	(92,312)	(81,442)
Distributions to noncontrolling interest in property partnership	(750)	(500)
Net cash provided by (used in) financing activities	(641,163)	257,102
Net increase (decrease) in cash and cash equivalents	(1,232,012)	268,357
Cash and cash equivalents, beginning of period	1,823,208	478,948
Cash and cash equivalents, end of period	591,196	747,305
Supplemental disclosures:
Cash paid for interest	140,508	71,213
Interest capitalized	11,201	11,239
Non-cash investing and financing activities:
Additions to real estate included in accounts payable	5,659	8,094
Mortgage note payable assumed in connection with the acquisition of real estate		143,900
Mortgage note payable extinguished through foreclosure	25,000
Real estate transferred upon foreclosure	7,644
Distributions declared but not paid	92,615	83,019
Conversions of redeemable partnership units to partners' capital	6,026	29,216
Conversion of redeemable preferred units to common units	4,115
Issuance of restricted securities to employees and directors	$ 26,139	$ 24,383

Organization

3 Months Ended

Mar. 31, 2012

Organization [Abstract]

Organization

1. 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 March 31, 2012 owned an approximate 88.4% (87.1% at March 31, 2011) 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 2008, February 2011 and February 2012, the Company issued LTIP Units in connection with the granting to employees of outperformance awards (also referred to as "2008 OPP Units," "2011 OPP Units" and "2012 OPP Units," respectively, and collectively as "OPP Units"). Because the rights, preferences and privileges of OPP 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. On February 5, 2011, the measurement period for the Company's 2008 OPP Unit awards expired and Boston Properties, Inc.'s total return to shareholders was not sufficient for employees to earn and therefore become eligible to vest in any of the 2008 OPP Unit awards. Accordingly, all 2008 OPP Unit awards were automatically forfeited (See Notes 8 and 11).

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 then value of a share of common stock of Boston Properties, Inc. ("Common Stock"). 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 11).

At March 31, 2012, there was one series of Preferred Units outstanding (i.e., Series Two 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. Preferred Units may also be converted into OP Units or redeemed for 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 8).

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

Properties

At March 31, 2012, the Company owned or had interests in a portfolio of 153 commercial real estate properties (the "Properties") aggregating approximately 43.3 million net rentable square feet, including eight properties under construction totaling approximately 2.8 million net rentable square feet. In addition, the Company has structured parking for approximately 44,703 vehicles containing approximately 15.2 million square feet. At March 31, 2012, the Properties consist of:

•

146 office properties, including 127 Class A office properties (including seven properties under construction) and 19 Office/Technical properties;

•

one hotel;

•

three retail properties; and

•

three residential properties (including one property under construction).

The Company owns or controls undeveloped land parcels totaling approximately 510.5 acres. In addition, the Company has a noncontrolling interest in the Boston Properties Office Value-Added Fund, L.P. (the "Value-Added Fund"), which is a strategic partnership with two institutional investors through which the Company has pursued the acquisition of value-added investments in assets within its existing markets. The Company's investments through the Value-Added Fund are not included in its portfolio information or any other portfolio level statistics. At March 31, 2012, the Value-Added Fund had investments in 24 buildings comprised of an office property in Chelmsford, Massachusetts and office complexes in Mountain View, California.

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.

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 2-6
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Name Statement of Position (SOP)
-Publisher AICPA
-Number 94-6
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Name FASB Interpretation (FIN)
-Publisher FASB
-Number 46R
-Paragraph 4, 14, 15
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6359553&loc=d3e288-107754

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2197480

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6921930&loc=d3e5614-111684

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 915
-SubTopic 235
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6472506&loc=d3e38932-110933

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2209116

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6970148&loc=SL6228881-111685

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/subtopic&trid=2122150

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6359566&loc=d3e326-107755

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 720
-SubTopic 15
-URI http://asc.fasb.org/subtopic&trid=2122524

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2134480

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS140-4/FIN46(R)-8
-Paragraph 8, C1, C7
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Basis Of Presentation And Summary Of Significant Accounting Policies

3 Months Ended

Mar. 31, 2012

Basis Of Presentation And Summary Of Significant Accounting Policies [Abstract]

Basis Of Presentation And Summary Of Significant Accounting Policies

2. Basis of Presentation and Summary of Significant Accounting Policies

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 affiliates 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.

The accompanying interim financial statements are unaudited; however, the financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the disclosures required by accounting principles generally accepted in the United States of America for complete financial statements. In the opinion of management, all adjustments (consisting solely of normal recurring matters) necessary for a fair statement of the financial statements for these interim periods have been included. The results of operations for the interim periods are not necessarily indicative of the results to be obtained for other interim periods or for the full fiscal year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosure required by accounting principles generally accepted in the United States of America. These financial statements should be read in conjunction with the Company's financial statements and notes thereto contained in the Company's Annual Report in the Company's Form 10-K for its fiscal year ended December 31, 2011. Certain prior year amounts have been reclassified to conform to the current year presentation.

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 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. 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 fair value of the Company's mortgage notes payable is 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 March 31, 2012 and December 31, 2011 (in thousands):


	March 31, 2012					December 31, 2011
	Carrying Amount			Estimated Fair Value		Carrying Amount			Estimated Fair Value
Mortgage notes payable	$	2,946,760		$	3,060,477	$	3,123,267		$	3,297,903
Unsecured senior notes		3,865,369			4,185,434		3,865,186			4,148,461
Unsecured exchangeable senior notes		1,148,497	(1)		1,328,799		1,715,685	(1)		1,904,115

Total	$	7,960,626		$	8,574,710	$	8,704,138		$	9,350,479

(1)	Includes the net impact of Accounting Standards Codification ("ASC") ASC 470-20 totaling approximately $46.3 million and $54.5 million at March 31, 2012 and December 31, 2011, respectively.

Out-of-Period Adjustment

During the three months ended March 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 three months ended March 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 that 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 three months ended March 31, 2012.

Real Estate Activity During The Three Months Ended March 31, 2012

3 Months Ended

Mar. 31, 2012

Real Estate Activity During The Three Months Ended March 31, 2012 [Abstract]

Real Estate Activity During The Three Months Ended March 31, 2012

3. Real Estate Activity During the Three Months Ended March 31, 2012

Acquisitions

On March 1, 2012, the Company acquired 453 Ravendale Drive located in Mountain View, California for a purchase price of approximately $6.7 million in cash. 453 Ravendale Drive is an approximately 30,000 net rentable square foot Office/Technical property. The following table summarizes the allocation of the aggregate purchase price of 453 Ravendale Drive at the date of acquisition (in thousands).


Land	$	5,477
Building and improvements		974
Tenant improvements		116
In-place lease intangibles		223
Below market rents		(140	)

Net assets acquired	$	6,650

On March 13, 2012, the Company acquired 100 Federal Street in Boston, Massachusetts for an aggregate investment of approximately $615.0 million in cash. In connection with the transaction, the Company entered into a long-term lease with an affiliate of Bank of America for approximately 735,000 square feet. 100 Federal Street is an approximately 1,264,000 net rentable square foot, 37-story Class A office tower located in Boston, Massachusetts. The following table summarizes the allocation of the aggregate purchase price of 100 Federal Street at the date of acquisition (in thousands).


Land	$	131,067
Building and improvements		387,321
Tenant improvements		48,633
In-place lease intangibles		69,530
Above market rents		81
Other assets		4,800
Below market rents		(22,515	)
Accounts payable and accrued expenses		(3,917	)

Net assets acquired	$	615,000

The following table summarizes the estimated amortization of the acquired above-market lease intangibles (net of acquired below-market lease intangibles) and the acquired in-place lease intangibles for 453 Ravendale Drive and 100 Federal Street, collectively, for each of the five succeeding years (in thousands).


	Acquired In-Place Lease Intangibles		Acquired Net Below- Market Lease Intangibles
Period from April 1, 2012 through December 31, 2012	$	8,149	$	2,992
2013		10,084		3,709
2014		7,869		3,374
2015		5,927		2,885
2016		5,199		2,512

The accompanying pro forma information for the three months ended March 31, 2012 and 2011 is presented as if the acquisition of (1) 453 Ravendale Drive on March 1, 2012 and (2) 100 Federal Street on March 13, 2012, had occurred on January 1, 2011. This pro forma information is based upon the historical consolidated financial statements 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	Three Months Ended March 31,
(in thousands, except per unit data)	2012		2011
Total revenue	$	461,789	$	433,603
Income from continuing operations	$	60,739	$	53,172
Net income attributable to Boston Properties Limited Partnership	$	77,597	$	51,323
Basic earnings per unit:
Net income per unit attributable to Boston Properties Limited Partnership	$	0.47	$	0.32
Diluted earnings per unit:
Net income per unit attributable to Boston Properties Limited Partnership	$	0.47	$	0.32

Developments

On January 3, 2012, the Company commenced the redevelopment of 12300 Sunrise Valley Drive, a Class A office project with approximately 256,000 net rentable square feet located in Reston, Virginia. The Company will capitalize incremental costs during the redevelopment.

Dispositions

On January 31, 2012, the servicer of the non-recourse mortgage loan collateralized by the Company's Montvale Center property located in Gaithersburg, Maryland foreclosed on the property. During 2011, the Company had notified the master servicer of the non-recourse mortgage loan that the cash flows generated from the property were insufficient to fund debt service payments and capital improvements necessary to lease and operate the property and that the Company was not prepared to fund any cash shortfalls. The Company was not current on making debt service payments and was accruing interest at the default interest rate of 9.93% per annum. The loan was originally scheduled to mature on June 6, 2012. As a result of the foreclosure, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate and working capital to the servicer. The Company no longer has any equitable or economic ownership interest in the property. The transaction resulted in a gain on forgiveness of debt of approximately $18.4 million. The operating results of the property through the date of foreclosure have been classified as discontinued operations on a historical basis for all periods presented.

The following table summarizes the loss from discontinued operations related to Montvale Center and the related gain on forgiveness of debt for the three months ended March 31, 2012 and 2011:


	For the three months ended March 31,
	2012			2011
	(in thousands)
Total revenue	$	222		$	661
Expenses
Operating		92			341
Depreciation and amortization		64			191

Total expenses		156			532
Operating income		66			129
Other expense
Interest expense		(222	)		(626	)

Loss from discontinued operations attributable to Boston Properties Limited Partnership	$	(156	)	$	(497	)

Gain on forgiveness of debt from discontinued operations attributable to Boston Properties Limited Partnership	$	18,361		$	—

- Definition

The entire disclosure for certain real estate investment financial statements, real estate investment trust operating support agreements, real estate owned, retail land sales, time share transactions, as well as other real estate related disclosures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 57
-Paragraph 2
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph c
-Subparagraph Schedule III
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 28
-Article 12

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 6
-Subparagraph a
-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher OTS
-Name Federal Regulation (FR)
-Number Title 12
-Chapter V
-Section 563c.102
-Paragraph 11
-Subsection I
-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 3
-Section A
-Paragraph 9
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 154
-Paragraph 22
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 67
-Paragraph 4, 5, 6, 7
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 46R
-Paragraph 23, 24
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 01-6
-Paragraph 13
-Subparagraph f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 15
-Paragraph 28
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 75-2
-Paragraph 47, 51, 52
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Audit and Accounting Guide (AAG)
-Number AAG-DEP
-Chapter 11
-Paragraph 2, 6, 9-11, 18, 20
-IssueDate 2006-05-01
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 04-2
-Paragraph 41, 63, 64
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 144
-Paragraph 7, 34
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 34
-Paragraph 9, 11, 12, 13, 14, 15, 21
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 66
-Paragraph 4, 5, 37, 50, 59, 65, 95, 97
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher OTS
-Name Federal Regulation (FR)
-Number Title 12
-Chapter V
-Section 563c.102
-Paragraph 10
-Subparagraph a, b
-Subsection I
-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 10
-Subparagraph 4
-Article 9

Reference 20: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 11
-Article 9

Reference 21: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28)
-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

+ Details

Investments In Unconsolidated Joint Ventures

3 Months Ended

Mar. 31, 2012

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures

4. Investments in Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at March 31, 2012:


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	Eighth Avenue and 46th Street		50.0	%(3)
Boston Properties Office Value-Added Fund, L.P.	300 Billerica Road and Mountain View Research and Technology Parks		37.6	%(1)(4)
Annapolis Junction NFM, LLC	Annapolis Junction		50.0	%(5)
767 Venture, LLC	The General Motors Building		60.0	%
2 GCT Venture LLC	Two Grand Central Tower		60.0	%(6)
540 Madison Venture LLC	540 Madison Avenue		60.0	%
125 West 55^thStreet Venture LLC	125 West 55^thStreet		60.0	%
500 North Capitol LLC	500 North Capitol Street, NW		30.0	%(7)

(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 owns a 33.3% interest in the entity owning the land and infrastructure of the project.

(3)	This property is not in operation and consists of assembled land.

(4)	Represents the Company's effective ownership interest. The Company has a 25.0% interest in the 300 Billerica Road property and a 39.5% interest in the Mountain View Research and Technology Park properties.

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

(6)	The property was sold on October 25, 2011. As of March 31, 2012, the investment is comprised of working capital and a portion of the sale proceeds.

(7)	This property is under construction.

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:


	March 31, 2012			December 31, 2011
	(in thousands)
ASSETS
Real estate and development in process, net	$	4,536,222		$	4,542,594
Other assets		658,851			668,113

Total assets	$	5,195,073		$	5,210,707

LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable	$	3,001,945		$	2,988,894
Other liabilities		829,981			854,257
Members'/Partners' equity		1,363,147			1,367,556

Total liabilities and members'/partners' equity	$	5,195,073		$	5,210,707

Company's share of equity	$	796,668		$	799,479
Basis differentials(1)		(129,291	)		(129,757	)

Carrying value of the Company's investments in unconsolidated joint ventures	$	667,377		$	669,722

(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 three months ended March 31,
	2012		2011
	(in thousands)
Total revenue(1)	$	139,100	$	145,645
Expenses
Operating		38,892		42,842
Depreciation and amortization		41,899		50,637

Total expenses		80,791		93,479
Operating income		58,309		52,166
Other expense
Interest expense		55,362		57,761

Net income (loss)	$	2,947	$	(5,595	)

Company's share of net income (loss)	$	1,371	$	(3,055	)
Basis differential		466		1,756
Elimination of inter-entity interest on partner loan		9,884		9,275

Income from unconsolidated joint ventures	$	11,721	$	7,976

(1)	Includes straight-line rent adjustments of $4.3 million and $4.1 million for the three months ended March 31, 2012 and 2011, respectively. Includes net "below-" market rent adjustments of $25.3 million and $29.5 million for the three months ended March 31, 2012 and 2011, respectively.

- Definition

The entire disclosure for equity investment, or group of investments, for which combined disclosure is appropriate, including: (a) the name of each investee and percentage of ownership of common stock, (b) accounting policies for investments in common stock, (c) difference between the amount at which the investment is carried and the amount of underlying equity in net assets and the accounting treatment of the difference, (d) the total fair value of each identified investment for which a market value is available, (e) summarized information as to assets, liabilities, and results of operations of the investees (for investments in unconsolidated subsidiaries, common stock of joint ventures, or other investments using the equity method), and (f) material effects of possible conversions, exercises, or contingent issuances of the investee. Other disclosures include (a) the names of any investee in which the investor owns 20 percent or more of the voting stock and investment is not accounted for using the equity method, and the reasons why not, and (b) the names of any investee in which the investor owns less than 20 percent of the voting stock and the investment is accounted for using the equity method, and the reasons why it is.

+ References + Details

Mortgage Notes Payable	3 Months Ended
Mortgage Notes Payable	Mar. 31, 2012
Mortgage Notes Payable [Abstract]
Mortgage Notes Payable	5. Mortgage Notes Payable On January 31, 2012, the servicer of the non-recourse mortgage loan collateralized by the Company's Montvale Center property located in Gaithersburg, Maryland foreclosed on the property. During 2011, the Company had notified the master servicer of the non-recourse mortgage loan that the cash flows generated from the property were insufficient to fund debt service payments and capital improvements necessary to lease and operate the property and that the Company was not prepared to fund any cash shortfalls. The Company was not current on making debt service payments and was accruing interest at the default interest rate of 9.93% per annum. The loan was originally scheduled to mature on June 6, 2012. As a result of the foreclosure, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate and working capital to the servicer. The Company no longer has any equitable or economic ownership interest in the property. The transaction resulted in a gain on forgiveness of debt of approximately $18.4 million. The operating results of the property through the date of foreclosure have been classified as discontinued operations on a historical basis for all periods presented (See Note 3). On March 12, 2012, the Company used available cash to repay the mortgage loan collateralized by its Bay Colony Corporate Center property located in Waltham, Massachusetts totaling $143.9 million. The mortgage financing bore interest at a fixed rate of 6.53% per annum and was scheduled to mature on June 11, 2012. There was no prepayment penalty. The Company recognized a gain on early extinguishment of debt totaling approximately $0.9 million related to the acceleration of the remaining balance of the historical fair value adjustment.

Unsecured Exchangeable Senior Notes

3 Months Ended

Mar. 31, 2012

Unsecured Exchangeable Senior Notes [Abstract]

Unsecured Exchangeable Senior Notes

6. Unsecured Exchangeable Senior Notes

The following summarizes the unsecured exchangeable senior notes outstanding as of March 31, 2012 (dollars in thousands):


	Coupon/ Stated Rate			Effective Rate(1)			Exchange Rate			Principal Amount			First Optional Redemption Date by Company			Maturity Date
3.625% Exchangeable Senior Notes		3.625	%		4.037	%		8.5051	(2)	$	747,500			N/A		February 15, 2014
3.750% Exchangeable Senior Notes		3.750	%		3.787	%		10.0066	(3)		450,000			May 18, 2013	(4)	May 15, 2036

Total principal											1,197,500
Net unamortized discount											(2,720	)
Adjustment for the equity component allocation, net of accumulated amortization											(46,283	)

Total										$	1,148,497

(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 adjustment), 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. As of March 31, 2012, the effective exchange price was $135.14 per share.

(3)

In connection with the special distribution of $5.98 per share of Boston Properties, Inc.'s common stock declared on December 17, 2007, the exchange rate was adjusted from 9.3900 to 10.0066 shares per $1,000 principal amount of notes effective as of December 31, 2007, resulting in an exchange price of approximately $99.93 per share of Boston Properties, Inc.'s common stock.

(4)

Holders may require the Company to repurchase the notes for cash on May 18, 2013 and May 15, 2016, 2021, 2026 and 2031 and at any time prior to their maturity upon a fundamental change, in each case at a price equal to 100% of the principal amount of the notes being repurchased plus any accrued and unpaid interest up to, but excluding, the repurchase date.

On January 10, 2012, the Company announced that holders of its 2.875% Exchangeable Senior Notes due 2037 (the "Notes") had the right to surrender their Notes for purchase by the Company (the "Put Right") on February 15, 2012. The opportunity to exercise the Put Right expired at 5:00 p.m., New York City time, on February 8, 2012. On January 10, 2012, the Company also announced that it had issued a notice of redemption to the holders of the Notes to redeem, on February 20, 2012 (the "Redemption Date"), all of the Notes outstanding on the Redemption Date. In connection with the redemption, holders of the Notes had the right to exchange their Notes prior to 5:00 p.m., New York City time, on February 16, 2012. Notes with respect to which the Put Right was not exercised (or with respect to which the Put Right was exercised and subsequently withdrawn prior to the withdrawal deadline) and that were not surrendered for exchange prior to 5:00 p.m., New York City time, on February 16, 2012, were redeemed by the Company on the Redemption Date 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. Holders of an aggregate of $242,735,000 of the Notes exercised the Put Right and the Company repurchased such Notes on February 15, 2012. On February 20, 2012, the Company redeemed the remaining $333,459,000 of outstanding Notes at a redemption price equal to 100% of the principal amount of the Notes plus accrued and unpaid interest thereon.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References + Details

Commitments And Contingencies	3 Months Ended
Commitments And Contingencies	Mar. 31, 2012
Commitments And Contingencies [Abstract]
Commitments And Contingencies	7. Commitments and Contingencies *General* In the normal course of business, the Company guarantees its performance of services or indemnifies third parties against its negligence. The Company has letter of credit and performance obligations of approximately $16.3 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 its interest in the joint ventures. Under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners. In connection with the assumption of the General Motors Building's secured loan by the Company's unconsolidated joint venture, 767 Venture, LLC, the Company guaranteed the unconsolidated joint venture's obligation to fund various escrows, including tenant improvements, taxes and insurance in lieu of cash deposits. As of March 31, 2012, the maximum funding obligation under the guarantee was approximately $13.5 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 refinancing in March 2010 of the 125 West 55^thStreet property's secured loan by the Company's unconsolidated joint venture, 125 West 55^thStreet Venture LLC, the Company has guaranteed the unconsolidated joint venture's obligation to fund an escrow related to certain lease rollover costs in lieu of an initial cash deposit for the full amount. The maximum funding obligation under the guarantee was $21.3 million. At closing, the joint venture funded a $10.0 million cash deposit into the escrow account and the remaining $11.3 million will be further reduced with scheduled monthly deposits into the escrow account from operating cash flows. As of March 31, 2012, the remaining funding obligation under the guarantee was approximately $0.5 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 One Freedom Square property located in Reston, Virginia, the Company has agreed to guarantee approximately $7.9 million related to its obligation to provide funds for certain tenant re-leasing costs. The mortgage financing was repaid on April 2, 2012 (See Note 13). 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. *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"). 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 the properties owned by the Company's Value-Added Fund and 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 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. 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 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 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 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 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 or the presence of mold at the Company's properties, 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.

- Definition

The entire disclosure for commitments and contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 14
-Paragraph 3
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9, 10, 11, 12
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6398077&loc=d3e12565-110249

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25287-109308

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6449706&loc=d3e16207-108621

+ Details

Noncontrolling Interests

3 Months Ended

Mar. 31, 2012

Noncontrolling Interests [Abstract]

Noncontrolling Interests

8. Noncontrolling Interests

Noncontrolling interests relate to the interests in the Company not owned by Boston Properties, Inc. and interests in property partnerships not wholly-owned by the Company. As of March 31, 2012, the noncontrolling interests consisted of 16,527,994 OP Units, 1,690,649 LTIP Units, 400,000 2011 OPP Units, 400,000 2012 OPP Units and 1,030,748 Series Two Preferred Units (or 1,352,688 OP Units on an as converted basis) held by parties other than Boston Properties, Inc.

Noncontrolling Interest—Redeemable Preferred Units

The Preferred Units at March 31, 2012 consisted solely of 1,030,748 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 14, 2013 and May 12, 2014. The maximum number of units that may be required to be redeemed from all holders on each of these dates is 1,007,662, which is one-sixth of the number of Series Two Preferred Units that were originally issued. 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 and May 14, 2012, although no holder exercised such right. The Company also has the right, subject to certain conditions, to redeem Series Two Preferred Units for cash or to convert into OP Units any Series Two Preferred Units that are not redeemed when they are eligible for redemption.

During the three months ended March 31, 2012, 82,296 Series Two Preferred Units of the Company were converted by the holders into 108,000 OP Units. In addition, the Company paid the accrued preferred distributions due to the holders of Preferred Units that were converted.

On February 15, 2012, the Company paid a distribution on its outstanding Series Two Preferred Units of $0.75616 per unit.

Due to the redemption option and the conversion option existing outside the control of the Company, the 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 March 31, 2012. The value of the Series Two Preferred Units, assuming all of such units had been converted and then redeemed at March 31, 2012, was approximately $142.0 million based on the closing price of Boston Properties, Inc.'s common stock of $104.99 per share on that date.

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


Balance at January 1, 2012	$	145,484
Net income		801
Distributions		(801	)
Reallocation of partnership interest(1)		(3,465	)

Balance at March 31, 2012	$	142,019

Balance at January 1, 2011	$	125,765
Net income		823
Distributions		(823	)
Reallocation of partnership interest		12,781

Balance at March 31, 2011	$	138,546

(1)	Includes the conversion of 82,296 Series Two Preferred Units into 108,000 OP Units during the three months ended March 31, 2012.

Noncontrolling Interest—Common Units

During the three months ended March 31, 2012, 199,526 OP Units were presented by the holders for redemption (including 108,000 OP Units issued upon conversion of Series Two Preferred Units and 54,472 OP Units 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 March 31, 2012, the Company had outstanding 400,000 2011 OPP Units and 400,000 2012 OPP Units (See Note 11). Prior to the measurement date (January 31, 2014 for 2011 OPP Units and February 6, 2015 for 2012 OPP Units), holders of OPP Units will be 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, both vested and unvested, that OPP 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 27, 2012, the Company paid a distribution on the OP Units and LTIP Units in the amount of $0.55 per unit, and a distribution on the 2011 OPP Units in the amount of $0.055 per unit, to holders of record as of the close of business on December 31, 2011. On March 16, 2012, Boston Properties, Inc., as general partner of the Company, declared a distribution on the OP Units and LTIP Units in the amount of $0.55 per unit and a distribution on the 2011 OPP Units and 2012 OPP Units in the amount of $0.055 per unit, in each case payable on April 30, 2012 to holders of record as of the close of business on March 30, 2012.

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


Balance at January 1, 2012	$	1,809,119
Contributions		24,443
Net income		8,031
Distributions		(10,064	)
Conversion of redeemable partnership units		(6,026	)
Unearned compensation		(14,857	)
Accumulated other comprehensive loss		69
Adjustment to reflect redeemable partnership units at redemption value		102,060

Balance at March 31, 2012	$	1,912,775

Balance at January 1, 2011	$	1,801,592
Contributions		22,803
Net income		6,029
Distributions		(10,078	)
Conversion of redeemable partnership units		(29,216	)
Unearned compensation		(13,558	)
Accumulated other comprehensive loss		80
Adjustment to reflect redeemable partnership units at redemption value		124,201

Balance at March 31, 2011	$	1,901,853

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 March 31, 2012 was approximately $1.91 billion based on the closing price of Boston Properties, Inc.'s common stock of $104.99 per share.

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 $(1.3) million at March 31, 2012 and approximately $(1.1) million at December 31, 2011, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.

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


Balance at January 1, 2012	$	(1,063	)
Net income		546
Distributions		(750	)

Balance at March 31, 2012	$	(1,267	)

Balance at January 1, 2011	$	(614	)
Net income		529
Distributions		(500	)

Balance at March 31, 2011	$	(585	)

- Definition

The entire disclosure for noncontrolling interest in consolidated subsidiaries, which could include the name of the subsidiary, the ownership percentage held by the parent, the ownership percentage held by the noncontrolling owners, the amount of the noncontrolling interest, the location of this amount on the balance sheet (when not reported separately), an explanation of the increase or decrease in the amount of the noncontrolling interest, the noncontrolling interest share of the net Income or Loss of the subsidiary, the location of this amount on the income statement (when not reported separately), the nature of the noncontrolling interest such as background information and terms, the amount of the noncontrolling interest represented by preferred stock, a description of the preferred stock, and the dividend requirements of the preferred stock.

+ References + Details

Partners' Capital	3 Months Ended
Partners' Capital	Mar. 31, 2012
Partners' Capital [Abstract]
Partners' Capital	9. Partners' Capital As of March 31, 2012, Boston Properties, Inc. owned 1,676,030 general partnership units and 147,708,311 limited partnership units. During the three months ended March 31, 2012, Boston Properties, Inc. utilized its $600 million "at the market" ("ATM") stock offering program to issue an aggregate of 1,048,800 shares of Common Stock for gross proceeds of approximately $110.5 million and net proceeds of approximately $109.3 million. Boston Properties, Inc. contributed the net proceeds from such sales to the Company in exchange for a number of OP Units equal to the number of shares issued. As of March 31, 2012, approximately $444.6 million remained available for issuance under this ATM program (See Note 13). During the three months ended March 31, 2012, the Company issued 17,706 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 three months ended March 31, 2012, Boston Properties, Inc. acquired 199,526 OP Units in connection with the redemption of an equal number of redeemable OP Units from third parties. On January 27, 2012, the Company paid a distribution in the amount of $0.55 per OP Unit to unitholders of record as of the close of business on December 31, 2011. On March 16, 2012, Boston Properties, Inc.'s Board of Directors declared a distribution in the amount of $0.55 per OP Unit payable on April 30, 2012 to unitholders of record as of the close of business on March 30, 2012.

- Definition

The entire disclosure for shareholders' equity, comprised of portions attributable to the parent entity and noncontrolling interest, if any, including other comprehensive income (as applicable). Including, but not limited to: (1) balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings; (2) accumulated balance for each classification of other comprehensive income and total amount of comprehensive income; (3) amount and nature of changes in separate accounts, including the number of shares authorized and outstanding, number of shares issued upon exercise and conversion, and for other comprehensive income, the adjustments for reclassifications to net income; (4) rights and privileges of each class of stock authorized; (5) basis of treasury stock, if other than cost, and amounts paid and accounting treatment for treasury stock purchased significantly in excess of market; (6) dividends paid or payable per share and in the aggregate for each class of stock for each period presented; (7) dividend restrictions and accumulated preferred dividends in arrears (in aggregate and per share amount); (8) retained earnings appropriations or restrictions, such as dividend restrictions; (9) impact of change in accounting principle, initial adoption of new accounting principle and correction of an error in previously issued financial statements; (10) shares held in trust for Employee Stock Ownership Plan (ESOP); (11) deferred compensation related to issuance of capital stock; (12) note received for issuance of stock; (13) unamortized discount on shares; (14) description, terms, and number of warrants or rights outstanding; (15) shares under subscription and subscription receivables, effective date of new retained earnings after quasi-reorganization and deficit eliminated by quasi-reorganization and, for a period of at least ten years after the effective date, the point in time from which the new retained dates; and (16) retroactive effective of subsequent change in capital structure.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 4
-Section 08
-Paragraph d

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
-Chapter 1
-Section B
-Paragraph 7, 11A
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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+ Details

Earnings Per Common Unit

3 Months Ended

Mar. 31, 2012

Earnings Per Common Unit [Abstract]

Earnings Per Common Unit

10. 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 Company. As a result, the Series Two Preferred Units are considered participating securities and are included in the computation of basic and diluted earnings per common unit of the Company if the effect of applying the if-converted method is dilutive. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are participating securities and shall be included in the computation of earnings per common unit pursuant to the two-class method. As a result, unvested restricted common stock of Boston Properties, Inc. and the Company's LTIP Units and OPP Units are considered participating securities and are included in the computation of basic and diluted earnings per common unit of the Company if the effect of applying the if-converted method is dilutive. Because the OPP 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. For the three months ended March 31, 2012, assuming the measurement period for the 2011 OPP Units ended on March 31, 2012, Boston Properties, Inc.'s total return to stockholders compared to the absolute and relative return thresholds for the 2011 OPP Units would have resulted in participants earning and being eligible to vest in an aggregate of approximately 129,000 2011 OPP Units. As a result, these 2011 OPP Units have been included in the diluted earnings per common unit calculation. For the three months ended March 31, 2012, the absolute and relative return thresholds for the 2012 OPP Units were not met and as a result the 2012 OPP Units have been excluded from the diluted earnings per common unit calculation. For the three months ended March 31, 2011, the absolute and relative return thresholds for the 2008 OPP Units and 2011 OPP Units were not met and as a result the 2008 OPP Units and 2011 OPP Units have been excluded 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 17,717,000 and 19,987,000 redeemable common units for the three months ended March 31, 2012 and 2011, respectively.


	For the three months ended March 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	$	57,066		166,060	$	0.34
Discontinued operations attributable to Boston Properties Limited Partnership		18,205		—		0.11

Net income attributable to Boston Properties Limited Partnership	$	75,271		166,060	$	0.45
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes		—		403		(0.00	)

Diluted Earnings:
Net income	$	75,271		166,463	$	0.45


	For the three months ended March 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	$	49,394			162,082	$	0.30
Discontinued operations attributable to Boston Properties Limited Partnership		(497	)		—		(0.00	)

Net income attributable to Boston Properties Limited Partnership	$	48,897			162,082	$	0.30
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes		—			409		(0.00	)

Diluted Earnings:
Net income	$	48,897			162,491	$	0.30

Stock Option And Incentive Plan	3 Months Ended
Stock Option And Incentive Plan	Mar. 31, 2012
Stock Option And Incentive Plan [Abstract]
Stock Option And Incentive Plan	11. Stock Option and Incentive Plan On January 25, 2012, the Compensation Committee of the Board of Directors of Boston Properties, Inc. approved outperformance awards under Boston Properties, Inc.'s 1997 Stock Option and Incentive Plan (the "1997 Plan") to certain officers of Boston Properties, Inc. These awards (the "2012 OPP Awards") are part of a broad-based, long-term incentive compensation program designed to provide the Company's management team with the potential to earn equity awards subject to Boston Properties, Inc. "outperforming" and creating shareholder value in a pay-for-performance structure. 2012 OPP Awards utilize total return to shareholders ("TRS") over a three-year measurement period as the performance metric and include two years of time-based vesting after the end of the performance measurement period (subject to acceleration in certain events) as a retention tool. Recipients of 2012 OPP Awards will share in an outperformance pool if Boston Properties, Inc.'s TRS, including both share appreciation and dividends, exceeds absolute and relative hurdles over a three-year measurement period from February 7, 2012 to February 6, 2015, based on the average closing price of a share of Boston Properties, Inc.'s common stock of $106.69 for the five trading days prior to and including February 7, 2012. The aggregate reward that recipients of all 2012 OPP Awards can earn, as measured by the outperformance pool, is subject to a maximum cap of $40.0 million. The outperformance pool will consist of (i) two percent (2%) of the excess total return above a cumulative absolute TRS hurdle of 24% over the full three-year measurement period (equivalent to 8% per annum) (the "Absolute TRS Component") and (ii) two percent (2%) of the excess or deficient excess total return above or below a relative TRS hurdle equal to the total return of the SNL Equity REIT Index over the three-year measurement period (the "Relative TRS Component"). In the event that the Relative TRS Component is potentially positive because Boston Properties, Inc.'s TRS is greater than the total return of the SNL Equity REIT Index, but Boston Properties, Inc. achieves a cumulative absolute TRS below 24% over the three-year measurement period (equivalent to 8% per annum), the actual contribution to the outperformance pool from the Relative TRS Component will be subject to a sliding scale factor as follows: (i) 100% of the potential Relative TRS Component will be earned if Boston Properties, Inc.'s TRS is equal to or greater than a cumulative 24% over three years, (ii) 0% will be earned if Boston Properties, Inc.'s TRS is 0% or less, and (iii) a percentage from 0% to 100% calculated by linear interpolation will be earned if Boston Properties, Inc.'s cumulative TRS over three years is between 0% and 24%. For example, if Boston Properties, Inc. achieves a cumulative absolute TRS of 18% over the full three-year measurement period (equivalent to a 6% absolute annual TRS), the potential Relative TRS Component would be prorated by 75%. The potential Relative TRS Component before application of the sliding scale factor will be capped at $40.0 million. In the event that the Relative TRS Component is negative because Boston Properties, Inc.'s TRS is less than the total return of the SNL Equity REIT Index, any outperformance reward potentially earned under the Absolute TRS Component will be reduced dollar for dollar, provided that the potential Absolute TRS Component before reduction for any negative Relative TRS Component will be capped at $40.0 million. The algebraic sum of the Absolute TRS Component and the Relative TRS Component determined as described above will never exceed $40.0 million. Each employee's 2012 OPP Award was designated as a specified percentage of the aggregate outperformance pool. Assuming the applicable absolute and/or relative TRS thresholds are achieved at the end of the measurement period, the algebraic sum of the Absolute TRS Component and the Relative TRS Component will be calculated and then allocated among the 2012 OPP Award recipients in accordance with each individual's percentage. If there is a change of control prior to February 6, 2015, the measurement period will end on the change of control date and both the Absolute TRS Component (using a prorated absolute TRS hurdle) and the Relative TRS Component will be calculated and, assuming the applicable absolute and/or relative TRS thresholds are achieved over the shorter measurement period, allocated among the 2012 OPP Award recipients as of that date. Rewards earned with respect to 2012 OPP Awards (if any) will vest 25% on February 7, 2015, 25% on February 7, 2016 and 50% on February 7, 2017, based on continued employment. Vesting will be accelerated in the event of a change in control of Boston Properties, Inc., termination of employment without cause, termination of employment by the award recipient for good reason, death, disability or retirement, although restrictions on transfer will continue to apply in certain of these situations. All determinations, interpretations and assumptions relating to the calculation of performance and vesting relating to 2012 OPP Awards will be made by the Compensation Committee. 2012 OPP Awards will be in the form of LTIP Units. LTIP Units will be issued prior to the determination of the outperformance pool, but will remain subject to forfeiture depending on the extent of rewards earned with respect to 2012 OPP Awards. The number of LTIP Units issued initially to recipients of the 2012 OPP Awards is an estimate of the maximum number of LTIP Units that they could earn, based on certain assumptions. The number of LTIP Units actually earned by each award recipient will be determined at the end of the performance measurement period by dividing his or her share of the outperformance pool by the average closing price of a REIT Share for the 15 trading days immediately preceding the measurement date. Total return for Boston Properties, Inc. and for the SNL Equity REIT Index over the three-year measurement period and other circumstances will determine how many LTIP Units are earned by each recipient; if they are fewer than the number issued initially, the balance will be forfeited as of the performance measurement date. Prior to the measurement date, LTIP units issued on account of 2012 OPP Awards will be 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 LTIP Units, both vested and unvested, which 2012 OPP Award recipients have earned 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. LTIP Units are designed to qualify as "profits interests" in the Company for federal income tax purposes. As a general matter, the profits interests characteristics of the LTIP Units mean that initially they will not be economically equivalent in value to an OP Unit. If and when events specified by applicable tax regulations occur, LTIP Units can over time increase in value up to the point where they are equivalent to OP Units on a one-for-one basis. After LTIP Units are fully vested, and to the extent the special tax rules applicable to profits interests have allowed them to become equivalent in value to OP Units, LTIP Units may be converted on a one-for-one basis into OP Units. OP Units in turn have a one-for-one relationship in value with Boston Properties, Inc. common stock, and are exchangeable on such one-for-one basis for cash or, at the election of Boston Properties, Inc., Boston Properties, Inc. common stock. The 2012 OPP Units were valued, in accordance with ASC 718 "Compensation—Stock Compensation," at an aggregate of approximately $7.7 million utilizing a Monte Carlo simulation to estimate the probability of the performance vesting conditions being satisfied. The Monte Carlo simulation used a statistical formula underlying the Black-Scholes and binomial formulas and such simulation was run approximately 100,000 times. For each simulation, the payoff is calculated at the settlement date, which is then discounted to the award date at a risk-free interest rate. The average of the values over all simulations is the expected value of the unit on the award date. Assumptions used in the valuations included (1) factors associated with the underlying performance of Boston Properties, Inc.'s stock price and total shareholder return over the term of the performance awards including total stock return volatility and risk-free interest and (2) factors associated with the relative performance of Boston Properties, Inc.'s stock price and total shareholder return when compared to the SNL Equity REIT Index. The valuation was performed in a risk-neutral framework, so no assumption was made with respect to an equity risk premium. The fair value of the 2012 OPP Units is based on the sum of: (1) the present value of the expected payoff to the OPP Award on the measurement date, if the TRS over the applicable measurement period exceeds performance hurdles of the Absolute and the Relative Components; and (2) the present value of the distributions payable on the 2012 OPP Units. The ultimate reward realized on account of the OPP Award by the holders of the 2012 OPP Units is contingent on the TRS achieved on the measurement date, both in absolute terms and relative to the TRS of the SNL Equity REIT Index. The per unit fair value of each 2012 OPP Unit was estimated on the date of grant using the following assumptions in the Monte Carlo valuation: expected price volatility for Boston Properties, Inc. and the SNL Equity REIT index of 31% and 30%, respectively; a risk free rate of 0.35%; and total dividend payments over the measurement period of $7.28 per share. On February 13, 2012, E. Mitchell Norville announced that he would resign as Executive Vice President, Chief Operating Officer of Boston Properties, Inc. effective on February 29, 2012. In connection with his resignation, Mr. Norville entered into a separation agreement (the "Separation Agreement") with Boston Properties, Inc. Under the Separation Agreement, Boston Properties, Inc. agreed to pay Mr. Norville cash payments totaling approximately $1,533,333 (less applicable deductions) in addition to his cash bonus for 2011, which was $950,000. In addition, Mr. Norville agreed to provide consulting services to Boston Properties, Inc. for at least two months following the effective date of his resignation for which he will receive $20,000 per month. Under the Separation Agreement, Mr. Norville is entitled to accelerated vesting with respect to 23,502 LTIP units in the Company and stock options to purchase 4,464 shares of common stock of Boston Properties, Inc. at an exercise price of $92.71 and 5,117 shares of common stock of Boston Properties, Inc. at an exercise price of $104.47. Mr. Norville will also retain approximately 36% of his 2011 outperformance award, which will remain subject to the performance-based vesting criteria originally established for the 2011 outperformance awards. Mr. Norville agreed to one-year non-competition, non-solicitation and non-interference provisions, and provided Boston Properties, Inc. with a general release of claims. The Company recognized approximately $4.5 million of expense during the three months ended March 31, 2012 in connection with Mr. Norville's resignation. During the three months ended March 31, 2012, Boston Properties, Inc. issued 19,521 shares of restricted common stock and 186,007 non-qualified stock options and the Company issued 169,301 LTIP Units and 400,000 2012 OPP Units to employees and non-employee directors under the 1997 Plan. Employees and directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit and OPP 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 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. The shares of restricted stock granted during the three months ended March 31, 2012 were valued at approximately $2.1 million ($107.57 per share). The non-qualified stock options granted during the three months ended March 31, 2012 had a weighted-average fair value on the date of grant of $19.50 per option, which was computed using the Black-Scholes option-pricing model utilizing the following weighted-average assumptions: an expected life of 5.4 years, a risk-free interest rate of 0.92%, an expected price volatility of 28.4% and an expected dividend yield of 2.9%. The weighted-average exercise price of the options is $107.23, which was the weighted-average closing price of Boston Properties, Inc.'s common stock on the date of grant. The LTIP Units granted during the three months ended March 31, 2012 were valued at approximately $16.8 million ($98.94 per unit fair value weighted-average) using a Monte Carlo simulation method model. The weighted-average per unit fair value of each LTIP Unit granted was estimated on the date of grant using the following assumptions: an expected life of 5.8 years, a risk-free interest rate of 0.94% and an expected price volatility of 29.1%. As the 2011 OPP Awards and 2012 OPP Awards are subject to both a service condition and a market condition, the Company recognizes the compensation expense related to the 2011 OPP Awards and 2012 OPP 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, 2008 OPP Units, 2011 OPP Units and 2012 OPP Units was approximately $10.9 million and $11.6 million for the three months ended March 31, 2012 and 2011, respectively. For the three months ended March 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 three months ended March 31, 2011. At March 31, 2012, there was $34.4 million of unrecognized compensation expense related to unvested restricted stock and LTIP Units and $11.4 million of unrecognized compensation expense related to unvested 2011 OPP Units and 2012 OPP Units that is expected to be recognized over a weighted-average period of approximately 3.0 years.

- Definition

Tabular disclosure of components of a stock option or other award plan under which equity-based compensation is awarded to employees, typically comprised of the amount of unearned compensation (deferred compensation cost), compensation expense, and changes in the quantity and fair value of the shares (or other type of equity) granted, exercised, forfeited, and issued and outstanding pertaining to that plan. Disclosure may also include nature and general terms of such arrangements that existed during the period and potential effects of those arrangements on shareholders, effect of compensation cost arising from equity-based payment arrangements on the income statement, method of estimating the fair value of the goods or services received, or the fair value of the equity instruments granted, during the period, cash flow effects resulting from equity-based payment arrangements and, for registrants that accelerate vesting of out of the money share options, reasons for the decision to accelerate.

+ References + Details

Segment Information

3 Months Ended

Mar. 31, 2012

Segment Information [Abstract]

Segment Information

12. 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. The Company's segments by geographic area are Boston, New York, Princeton, 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 from investments in securities, gains from early extinguishments of debt, income from unconsolidated joint ventures, 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.

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

For the three months ended March 31, 2012:


	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	140,871		$	117,589		$	14,850		$	52,197		$	90,398		$	415,905
Office/Technical		8,167			—			—			52			4,092			12,311
Residential		883			—			—			—			3,598			4,481
Hotel		6,816			—			—			—			—			6,816

Total		156,737			117,589			14,850			52,249			98,088			439,513

% of Grand Totals		35.66	%		26.75	%		3.38	%		11.89	%		22.32	%		100.0	%
Rental Expenses:
Class A Office		57,890			38,429			7,358			20,091			27,442			151,210
Office/Technical		2,510			—			—			24			1,047			3,581
Residential		390			—			—			—			2,325			2,715
Hotel		6,099			—			—			—			—			6,099

Total		66,889			38,429			7,358			20,115			30,814			163,605

% of Grand Totals		40.89	%		23.49	%		4.50	%		12.29	%		18.83	%		100.0	%

Net operating income	$	89,848		$	79,160		$	7,492		$	32,134		$	67,274		$	275,908

% of Grand Totals		32.56	%		28.69	%		2.72	%		11.65	%		24.38	%		100.0	%

For the three months ended March 31, 2011:


	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	127,429		$	113,007		$	16,279		$	52,893		$	82,680		$	392,288
Office/Technical		7,558			—			—			—			3,992			11,550
Residential		—			—			—			—			—			—
Hotel		5,948			—			—			—			—			5,948

Total		140,935			113,007			16,279			52,893			86,672			409,786

% of Grand Totals		34.39	%		27.58	%		3.97	%		12.91	%		21.15	%		100.0	%
Rental Expenses:
Class A Office		47,901			37,715			7,915			19,333			23,165			136,029
Office/Technical		2,479			—			—			—			1,122			3,601
Residential		—			—			—			—			—			—
Hotel		5,739			—			—			—			—			5,739

Total		56,119			37,715			7,915			19,333			24,287			145,369

% of Grand Totals		38.61	%		25.94	%		5.44	%		13.30	%		16.71	%		100.0	%

Net operating income	$	84,816		$	75,292		$	8,364		$	33,560		$	62,385		$	264,417

% of Grand Totals		32.08	%		28.48	%		3.16	%		12.69	%		23.59	%		100.0	%

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


	Three months ended March 31,
	2012		2011
Net Operating Income	$	275,908	$	264,417
Add:
Development and management services income		8,149		7,428
Income from unconsolidated joint ventures		11,721		7,976
Interest and other income		1,646		974
Gains from investments in securities		801		373
Gains from early extinguishments of debt		767		—
Gain on forgiveness of debt from discontinued operations		18,361		—
Less:
General and administrative expense		27,619		24,643
Transaction costs		2,104		72
Depreciation and amortization expense		107,619		107,182
Interest expense		103,237		98,525
Loss from discontinued operations		156		497
Noncontrolling interest in property partnerships		546		529
Noncontrolling interest—redeemable preferred units		801		823

Net income attributable to Boston Properties Limited Partnership	$	75,271	$	48,897

- 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 Statement of Financial Accounting Standard (FAS)
-Number 131
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-Paragraph 34
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2012
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events From April 1, 2012 through May 8, 2012, Boston Properties, Inc. issued an aggregate of 643,600 shares of its Common Stock under the ATM program for gross proceeds of approximately $68.4 million and net proceeds of approximately $67.7 million. Boston Properties, Inc. contributed the net proceeds from such sales to the Company in exchange for a number of OP Units equal to the number of shares issued. As of May 8, 2012, approximately $376.2 million remained available for issuance under this ATM program. On April 2, 2012, the Company used available cash to repay the mortgage loan collateralized by its One Freedom Square property located in Reston, Virginia totaling $65.1 million. The mortgage financing bore interest at a fixed rate of 7.75% per annum and was scheduled to mature on June 30, 2012. There was no prepayment penalty. On April 30, 2012, the Company completed and placed in-service 510 Madison Avenue, a Class A office project with approximately 347,000 net rentable square feet located in New York City. On May 1, 2012, the Company entered into an agreement to sell its Bedford Business Park properties located in Bedford, Massachusetts for approximately $62.8 million in cash. Bedford Business Park is comprised of two Office/Technical buildings and one Class A office building aggregating approximately 470,000 net rentable square feet. The sale is subject to the satisfaction of customary closing conditions and there can be no assurance that the sale will be consummated on the terms currently contemplated or at all. On May 3, 2012, the Company completed and placed in-service 12310 Sunrise Valley Drive, a Class A office redevelopment project with approximately 268,000 net rentable square feet located in Reston, Virginia.

Basis Of Presentation And Summary Of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2012

Basis Of Presentation And Summary Of Significant Accounting Policies [Abstract]

Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value


	March 31, 2012					December 31, 2011
	Carrying Amount			Estimated Fair Value		Carrying Amount			Estimated Fair Value
Mortgage notes payable	$	2,946,760		$	3,060,477	$	3,123,267		$	3,297,903
Unsecured senior notes		3,865,369			4,185,434		3,865,186			4,148,461
Unsecured exchangeable senior notes		1,148,497	(1)		1,328,799		1,715,685	(1)		1,904,115

Total	$	7,960,626		$	8,574,710	$	8,704,138		$	9,350,479

(1)	Includes the net impact of Accounting Standards Codification ("ASC") ASC 470-20 totaling approximately $46.3 million and $54.5 million at March 31, 2012 and December 31, 2011, respectively.

- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 14
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 107
-Paragraph 15
-Subparagraph b-d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 157
-Paragraph 32
-Subparagraph a, c(1), c(2), c(3), d
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 18
-Subparagraph c(2), d, e, f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 19
-Subparagraph a, b, c(1), d(1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 825
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-Section 50
-Paragraph 10
-Subparagraph (a)
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-URI http://asc.fasb.org/extlink&oid=6447952&loc=d3e13220-108610

+ Details

Real Estate During The Three Months Ended March 31, 2012 (Tables)

3 Months Ended

Mar. 31, 2012

Real Estate Properties [Line Items]

Estimated Amortization Of The Acquired Above-Market Leases (Net Of Acquired Below-Market Leases) And The Acquired In-Place Lease Intangibles


	Acquired In-Place Lease Intangibles		Acquired Net Below- Market Lease Intangibles
Period from April 1, 2012 through December 31, 2012	$	8,149	$	2,992
2013		10,084		3,709
2014		7,869		3,374
2015		5,927		2,885
2016		5,199		2,512

Pro Forma In Connection With Acquisition


Pro Forma	Three Months Ended March 31,
(in thousands, except per unit data)	2012		2011
Total revenue	$	461,789	$	433,603
Income from continuing operations	$	60,739	$	53,172
Net income attributable to Boston Properties Limited Partnership	$	77,597	$	51,323
Basic earnings per unit:
Net income per unit attributable to Boston Properties Limited Partnership	$	0.47	$	0.32
Diluted earnings per unit:
Net income per unit attributable to Boston Properties Limited Partnership	$	0.47	$	0.32

Summary Of The Discontinued Operations Related To Montvale Center


	For the three months ended March 31,
	2012			2011
	(in thousands)
Total revenue	$	222		$	661
Expenses
Operating		92			341
Depreciation and amortization		64			191

Total expenses		156			532
Operating income		66			129
Other expense
Interest expense		(222	)		(626	)

Loss from discontinued operations attributable to Boston Properties Limited Partnership	$	(156	)	$	(497	)

Gain on forgiveness of debt from discontinued operations attributable to Boston Properties Limited Partnership	$	18,361		$	—

453 Ravendale Drive [Member]

Real Estate Properties [Line Items]

Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition


Land	$	5,477
Building and improvements		974
Tenant improvements		116
In-place lease intangibles		223
Below market rents		(140	)

Net assets acquired	$	6,650

100 Federal Street [Member]

Real Estate Properties [Line Items]

Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition


Land	$	131,067
Building and improvements		387,321
Tenant improvements		48,633
In-place lease intangibles		69,530
Above market rents		81
Other assets		4,800
Below market rents		(22,515	)
Accounts payable and accrued expenses		(3,917	)

Net assets acquired	$	615,000

- Definition

Tabular disclosure of pro forma results of operations for a material business acquisition or series of individually immaterial business acquisitions that are material in the aggregate.

+ References + Details

- Definition

Tabular disclosure of a material business combination completed during the period, including background, timing, and recognized assets and liabilities. This table does not include leveraged buyouts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 51
-Subparagraph a
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141
-Paragraph 52
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Paragraph 68
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 141R
-Appendix F
-Paragraph F4
-Subparagraph e

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
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-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6972119&loc=d3e1486-128463

+ Details

- 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

Investments In Unconsolidated Joint Ventures (Tables)

3 Months Ended

Mar. 31, 2012

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures


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	Eighth Avenue and 46th Street		50.0	%(3)
Boston Properties Office Value-Added Fund, L.P.	300 Billerica Road and Mountain View Research and Technology Parks		37.6	%(1)(4)
Annapolis Junction NFM, LLC	Annapolis Junction		50.0	%(5)
767 Venture, LLC	The General Motors Building		60.0	%
2 GCT Venture LLC	Two Grand Central Tower		60.0	%(6)
540 Madison Venture LLC	540 Madison Avenue		60.0	%
125 West 55^thStreet Venture LLC	125 West 55^thStreet		60.0	%
500 North Capitol LLC	500 North Capitol Street, NW		30.0	%(7)

(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 owns a 33.3% interest in the entity owning the land and infrastructure of the project.

(3)	This property is not in operation and consists of assembled land.

(4)	Represents the Company's effective ownership interest. The Company has a 25.0% interest in the 300 Billerica Road property and a 39.5% interest in the Mountain View Research and Technology Park properties.

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

(6)	The property was sold on October 25, 2011. As of March 31, 2012, the investment is comprised of working capital and a portion of the sale proceeds.

(7)	This property is under construction.

Balance Sheets Of The Unconsolidated Joint Ventures


	March 31, 2012			December 31, 2011
	(in thousands)
ASSETS
Real estate and development in process, net	$	4,536,222		$	4,542,594
Other assets		658,851			668,113

Total assets	$	5,195,073		$	5,210,707

LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable	$	3,001,945		$	2,988,894
Other liabilities		829,981			854,257
Members'/Partners' equity		1,363,147			1,367,556

Total liabilities and members'/partners' equity	$	5,195,073		$	5,210,707

Company's share of equity	$	796,668		$	799,479
Basis differentials(1)		(129,291	)		(129,757	)

Carrying value of the Company's investments in unconsolidated joint ventures	$	667,377		$	669,722

(1)

Statements Of Operations Of The Joint Ventures


	For the three months ended March 31,
	2012		2011
	(in thousands)
Total revenue(1)	$	139,100	$	145,645
Expenses
Operating		38,892		42,842
Depreciation and amortization		41,899		50,637

Total expenses		80,791		93,479
Operating income		58,309		52,166
Other expense
Interest expense		55,362		57,761

Net income (loss)	$	2,947	$	(5,595	)

Company's share of net income (loss)	$	1,371	$	(3,055	)
Basis differential		466		1,756
Elimination of inter-entity interest on partner loan		9,884		9,275

Income from unconsolidated joint ventures	$	11,721	$	7,976

(1)	Includes straight-line rent adjustments of $4.3 million and $4.1 million for the three months ended March 31, 2012 and 2011, respectively. Includes net "below-" market rent adjustments of $25.3 million and $29.5 million for the three months ended March 31, 2012 and 2011, respectively.

Unsecured Exchangeable Senior Notes (Tables)

3 Months Ended

Mar. 31, 2012

Unsecured Exchangeable Senior Notes [Abstract]

Schedule of Unsecured Exchangeable Senior Notes


	Coupon/ Stated Rate			Effective Rate(1)			Exchange Rate			Principal Amount			First Optional Redemption Date by Company			Maturity Date
3.625% Exchangeable Senior Notes		3.625	%		4.037	%		8.5051	(2)	$	747,500			N/A		February 15, 2014
3.750% Exchangeable Senior Notes		3.750	%		3.787	%		10.0066	(3)		450,000			May 18, 2013	(4)	May 15, 2036

Total principal											1,197,500
Net unamortized discount											(2,720	)
Adjustment for the equity component allocation, net of accumulated amortization											(46,283	)

Total										$	1,148,497

(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)

(3)

(4)

- 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 SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

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-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

+ Details

Noncontrolling Interests (Tables)

3 Months Ended

Mar. 31, 2012

Noncontrolling Interests [Abstract]

Noncontrolling Interests - Redeemable Preferred Units


Balance at January 1, 2012	$	145,484
Net income		801
Distributions		(801	)
Reallocation of partnership interest(1)		(3,465	)

Balance at March 31, 2012	$	142,019

Balance at January 1, 2011	$	125,765
Net income		823
Distributions		(823	)
Reallocation of partnership interest		12,781

Balance at March 31, 2011	$	138,546

(1)	Includes the conversion of 82,296 Series Two Preferred Units into 108,000 OP Units during the three months ended March 31, 2012.

Noncontrolling Interests-Redeemable Common Units


Balance at January 1, 2012	$	1,809,119
Contributions		24,443
Net income		8,031
Distributions		(10,064	)
Conversion of redeemable partnership units		(6,026	)
Unearned compensation		(14,857	)
Accumulated other comprehensive loss		69
Adjustment to reflect redeemable partnership units at redemption value		102,060

Balance at March 31, 2012	$	1,912,775

Balance at January 1, 2011	$	1,801,592
Contributions		22,803
Net income		6,029
Distributions		(10,078	)
Conversion of redeemable partnership units		(29,216	)
Unearned compensation		(13,558	)
Accumulated other comprehensive loss		80
Adjustment to reflect redeemable partnership units at redemption value		124,201

Balance at March 31, 2011	$	1,901,853

Noncontrolling Interests-Property Partnerships


Balance at January 1, 2012	$	(1,063	)
Net income		546
Distributions		(750	)

Balance at March 31, 2012	$	(1,267	)

Balance at January 1, 2011	$	(614	)
Net income		529
Distributions		(500	)

Balance at March 31, 2011	$	(585	)

Earnings Per Common Unit (Tables)

3 Months Ended

Mar. 31, 2012

Earnings Per Common Unit [Abstract]

Computation Of Basic And Diluted Earnings Per Unit


	For the three months ended March 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	$	57,066		166,060	$	0.34
Discontinued operations attributable to Boston Properties Limited Partnership		18,205		—		0.11

Net income attributable to Boston Properties Limited Partnership	$	75,271		166,060	$	0.45
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes		—		403		(0.00	)

Diluted Earnings:
Net income	$	75,271		166,463	$	0.45


	For the three months ended March 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	$	49,394			162,082	$	0.30
Discontinued operations attributable to Boston Properties Limited Partnership		(497	)		—		(0.00	)

Net income attributable to Boston Properties Limited Partnership	$	48,897			162,082	$	0.30
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes		—			409		(0.00	)

Diluted Earnings:
Net income	$	48,897			162,491	$	0.30

Segment Information (Tables)

3 Months Ended

Mar. 31, 2012

Segment Information [Abstract]

Schedule Of Segment Information By Geographic Area And Property Type

For the three months ended March 31, 2012:


	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	140,871		$	117,589		$	14,850		$	52,197		$	90,398		$	415,905
Office/Technical		8,167			—			—			52			4,092			12,311
Residential		883			—			—			—			3,598			4,481
Hotel		6,816			—			—			—			—			6,816

Total		156,737			117,589			14,850			52,249			98,088			439,513

% of Grand Totals		35.66	%		26.75	%		3.38	%		11.89	%		22.32	%		100.0	%
Rental Expenses:
Class A Office		57,890			38,429			7,358			20,091			27,442			151,210
Office/Technical		2,510			—			—			24			1,047			3,581
Residential		390			—			—			—			2,325			2,715
Hotel		6,099			—			—			—			—			6,099

Total		66,889			38,429			7,358			20,115			30,814			163,605

% of Grand Totals		40.89	%		23.49	%		4.50	%		12.29	%		18.83	%		100.0	%

Net operating income	$	89,848		$	79,160		$	7,492		$	32,134		$	67,274		$	275,908

% of Grand Totals		32.56	%		28.69	%		2.72	%		11.65	%		24.38	%		100.0	%

For the three months ended March 31, 2011:


	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	127,429		$	113,007		$	16,279		$	52,893		$	82,680		$	392,288
Office/Technical		7,558			—			—			—			3,992			11,550
Residential		—			—			—			—			—			—
Hotel		5,948			—			—			—			—			5,948

Total		140,935			113,007			16,279			52,893			86,672			409,786

% of Grand Totals		34.39	%		27.58	%		3.97	%		12.91	%		21.15	%		100.0	%
Rental Expenses:
Class A Office		47,901			37,715			7,915			19,333			23,165			136,029
Office/Technical		2,479			—			—			—			1,122			3,601
Residential		—			—			—			—			—			—
Hotel		5,739			—			—			—			—			5,739

Total		56,119			37,715			7,915			19,333			24,287			145,369

% of Grand Totals		38.61	%		25.94	%		5.44	%		13.30	%		16.71	%		100.0	%

Net operating income	$	84,816		$	75,292		$	8,364		$	33,560		$	62,385		$	264,417

% of Grand Totals		32.08	%		28.48	%		3.16	%		12.69	%		23.59	%		100.0	%

Schedule Of Reconciliation Of Net Operating Income To Net Income


	Three months ended March 31,
	2012		2011
Net Operating Income	$	275,908	$	264,417
Add:
Development and management services income		8,149		7,428
Income from unconsolidated joint ventures		11,721		7,976
Interest and other income		1,646		974
Gains from investments in securities		801		373
Gains from early extinguishments of debt		767		—
Gain on forgiveness of debt from discontinued operations		18,361		—
Less:
General and administrative expense		27,619		24,643
Transaction costs		2,104		72
Depreciation and amortization expense		107,619		107,182
Interest expense		103,237		98,525
Loss from discontinued operations		156		497
Noncontrolling interest in property partnerships		546		529
Noncontrolling interest—redeemable preferred units		801		823

Net income attributable to Boston Properties Limited Partnership	$	75,271	$	48,897

- Definition

Tabular disclosure of the profit or loss and total assets for each reportable segment. An entity discloses certain information on each reportable segment if the amounts (a) are included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) are otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

+ References + Details

Organization (Details) ft² in Millions	3 Months Ended
Organization (Details) ft² in Millions	Mar. 31, 2012 ft² a yr shares	Mar. 31, 2011
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership	88.40%	87.10%
Restriction on redemption of OP units from date of issuance (years) \| yr	1
One OP unit is equivalent to one share of Common Stock	1
Number of series of preferred units outstanding	1
OP unit conversion rate	1
Number of vehicles in structured parking	44,703
Area of parking in square feet \| ft²	15.2
Area of undeveloped land parcels owned in acres \| a	510.5
Value-added fund institutional investors	2
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Square footage of real estate property	43,300,000
Number of real estate properties	153
Total Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	146
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Square footage of real estate property	2,800,000
Number of real estate properties	8
Office Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	7
Class A Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	127
Office/Technical Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	19
Hotel Property [ 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	3
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
Investments Through Value-Added Fund [Member]
Real Estate Properties [Line Items]
Number of real estate properties	24

Basis Of Presentation And Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2012 USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Abstract]
Misstatement of real estate operating expense	$ 3.2

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

Mar. 31, 2012

Dec. 31, 2011

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable, net

$ 2,946,760

$ 3,123,267

Unsecured senior notes

3,865,369

3,865,186

Unsecured exchangeable senior notes

1,148,497

1,715,685

Net of the adjustment for the equity component allocation

46,283

Carrying Amount [Member]

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable, net

2,946,760

3,123,267

Unsecured senior notes

3,865,369

3,865,186

Unsecured exchangeable senior notes

^[1]

1,148,497

1,715,685

Total

7,960,626

8,704,138

Estimated Fair Value [Member]

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable, net

3,060,477

3,297,903

Unsecured senior notes

4,185,434

4,148,461

Unsecured exchangeable senior notes

1,328,799

1,904,115

Total

8,574,710

9,350,479

ASC 470-20 Adjustment [Member]

Summary Of Significant Accounting Policies [Line Items]

Net of the adjustment for the equity component allocation

$ 46,300

$ 54,500

[1]	Includes the net impact of Accounting Standards Codification ("ASC") ASC 470-20 totaling approximately $46.3 million and $54.5 million at March 31, 2012 and December 31, 2011, respectively.

Real Estate Activity During The Three Months Ended March 31, 2012 (Narrative) (Details) $ in Thousands				3 Months Ended
	Mar. 13, 2012 USD ($) ft² floor	Mar. 01, 2012 USD ($)	Jan. 03, 2012	Mar. 31, 2012 USD ($)
Real Estate Properties [Line Items]
Discontinued operations gain				$ 18,361
12300 Sunrise Valley Drive [Member]
Real Estate Properties [Line Items]
Square footage of real estate property			256,000
453 Ravendale Drive [Member]
Real Estate Properties [Line Items]
Acquisition date				March 1, 2012
Acquisition aggregate purchase price		$ 6,700
Square footage of real estate property		30,000
100 Federal Street [Member]
Real Estate Properties [Line Items]
Acquisition date				March 13, 2012
Acquisition aggregate purchase price	$ 615,000
Square footage of real estate property	1,264,000
Square footage of signed lease \| ft²	735,000
Number of floors in building \| floor	37
Montvale Center [Member]
Real Estate Properties [Line Items]
Maturity date				Jun. 06, 2012
Debt default, accrued interest rate				9.93%
Amount of debt extinguished				$ 25,000
Discontinued operations gain				$ 18,361

Real Estate Activity During The Three Months Ended March 31, 2012 (Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition) (Details) - USD ($) $ in Thousands	Mar. 13, 2012	Mar. 01, 2012
453 Ravendale Drive [Member]
Restructuring Cost and Reserve [Line Items]
Land		$ 5,477
Building and improvements		974
Tenant improvements		116
In-place lease intangibles		223
Below market rents		(140)
Net assets acquired		$ 6,650
100 Federal Street [Member]
Restructuring Cost and Reserve [Line Items]
Land	$ 131,067
Building and improvements	387,321
Tenant improvements	48,633
In-place lease intangibles	69,530
Above market rents	81
Other assets	4,800
Below market rents	(22,515)
Accounts payable and accrued expenses	(3,917)
Net assets acquired	$ 615,000

Real Estate Activity During The Three Months Ended March 31, 2012 (Summary Of Estimated Amortization Of The Acquired Above-Market Leases (Net Of Acquired Below-Market Leases) And The Acquired In-Place Lease Intangibles) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2012 USD ($)
Acquired In-Place Lease Intangibles [Member]
Restructuring Cost and Reserve [Line Items]
Period from April 1, 2012 through December 31, 2012	$ 8,149
2013	10,084
2014	7,869
2015	5,927
2016	5,199
Acquired Net Above-Market Lease Intangibles [Member]
Restructuring Cost and Reserve [Line Items]
Period from April 1, 2012 through December 31, 2012	2,992
2013	3,709
2014	3,374
2015	2,885
2016	$ 2,512

Real Estate Activity During The Three Months Ended March 31, 2012 (Pro Forma In Connection With Acquisition) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Real Estate Activity During The Three Months Ended March 31, 2012 [Abstract]
Total revenue	$ 461,789	$ 433,603
Income from continuing operations	60,739	53,172
Net income attributable to Boston Properties Limited Partnership	$ 77,597	$ 51,323
Basic earnings per unit: Net income per unit attributable to Boston Properties Limited Partnership	$ 0.47	$ 0.32
Diluted earnings per unit: Net income per unit attributable to Boston Properties Limited Partnership	$ 0.47	$ 0.32

- Definition

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References + Details

- Definition

The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References + Details

Real Estate Activity During The Three Months Ended March 31, 2012 (Summary Of The Discontinued Operations Related To Montvale Center) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue	$ 447,662	$ 417,214
Depreciation and amortization expense	107,619	107,182
Total expenses	300,947	277,266
Operating income	146,715	139,948
Interest expense	(103,237)	(98,525)
Loss from discontinued operations attributable to Boston Properties Limited Partnership	18,205	(497)
Gain on forgiveness of debt from discontinued operations attributable to Boston Properties Limited Partnership	18,361
Montvale Center [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue	222	661
Operating expenses	92	341
Depreciation and amortization expense	64	191
Total expenses	156	532
Operating income	66	129
Interest expense	(222)	(626)
Loss from discontinued operations attributable to Boston Properties Limited Partnership	(156)	$ (497)
Gain on forgiveness of debt from discontinued operations attributable to Boston Properties Limited Partnership	$ 18,361

Investments In Unconsolidated Joint Ventures (Investments In Unconsolidated Joint Ventures) (Details)

3 Months Ended

Mar. 31, 2012

property

Square 407 Limited Partnership [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

50.00%

Properties

Market Square North

The Metropolitan Square Associates LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

51.00%

Properties

Metropolitan Square

BP/CRF 901 New York Avenue LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

25.00%

^[1]

Properties

901 New York Avenue

^[1]

WP Project Developer LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

33.30%

^[2]

Properties

Wisconsin Place Land and Infrastructure

^[2]

RBP Joint Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

50.00%

^[3]

Properties

Eighth Avenue and 46th Street

^[3]

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

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

37.60%

^[1],[4]

Properties

300 Billerica Road and Mountain View Research and Technology Parks

^[1],[4]

Annapolis Junction NFM, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

50.00%

^[5]

Properties

Annapolis Junction

^[5]

Number of real estate properties

Number of buildings under construction

Parcels of undeveloped land

767 Venture, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

60.00%

Properties

The General Motors Building

2 GCT Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

60.00%

^[6]

Properties

Two Grand Central Tower

^[6]

540 Madison Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

60.00%

Properties

540 Madison Avenue

125 West 55th Street Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

60.00%

Properties

125 West 55th Street

500 North Capitol LLC [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

30.00%

^[7]

Properties

500 North Capitol Street, NW

^[7]

Entity Owning Land And Infrastructure Of Project [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

33.30%

300 Billerica Road [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

25.00%

Mountain View Research And Technology Park [Member]

Schedule of Equity Method Investments [Line Items]

Nominal % Ownership

39.50%

[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 owns a 33.3% interest in the entity owning the land and infrastructure of the project.
[3]	This property is not in operation and consists of assembled land.
[4]	Represents the Company's effective ownership interest. The Company has a 25.0% interest in the 300 Billerica Road property and a 39.5% interest in the Mountain View Research and Technology Park properties.
[5]	Comprised of one building, one building under construction and two undeveloped land parcels.
[6]	The property was sold on October 25, 2011. As of March 31, 2012, the investment is comprised of working capital and a portion of the sale proceeds.
[7]	This property is under construction.

Investments In Unconsolidated Joint Ventures (Balance Sheets Of The Unconsolidated Joint Ventures) (Details) - USD ($)
$ in Thousands

Mar. 31, 2012

Dec. 31, 2011

Schedule of Equity Method Investments [Line Items]

Real estate and development in process, net

$ 10,964,242

$ 10,355,546

Mortgage and Notes payable

2,946,760

3,123,267

Other liabilities

324,826

293,515

Total liabilities and members'/partners' equity

13,824,525

14,392,026

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

667,377

669,722

Unconsolidated Joint Ventures [Member]

Schedule of Equity Method Investments [Line Items]

Real estate and development in process, net

4,536,222

4,542,594

Other assets

658,851

668,113

Total assets

5,195,073

5,210,707

Mortgage and Notes payable

3,001,945

2,988,894

Other liabilities

829,981

854,257

Members'/Partners' equity

1,363,147

1,367,556

Total liabilities and members'/partners' equity

5,195,073

5,210,707

Company's share of equity

796,668

799,479

Basis differentials

^[1]

(129,291)

(129,757)

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

$ 667,377

$ 669,722

[1]

Investments In Unconsolidated Joint Ventures (Statements Of Operations Of The Joint Ventures) (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2012

Mar. 31, 2011

Schedule of Equity Method Investments [Line Items]

Total revenue

$ 447,662

$ 417,214

Depreciation and amortization

107,619

107,182

Total expenses

300,947

277,266

Operating income

146,715

139,948

Interest expense

103,237

98,525

Net income (loss)

76,618

50,249

Income from unconsolidated joint ventures

11,721

7,976

Unconsolidated Joint Ventures [Member]

Schedule of Equity Method Investments [Line Items]

Total revenue

^[1]

139,100

145,645

Operating

38,892

42,842

Depreciation and amortization

41,899

50,637

Total expenses

80,791

93,479

Operating income

58,309

52,166

Interest expense

55,362

57,761

Net income (loss)

2,947

(5,595)

Company's share of net income (loss)

1,371

(3,055)

Basis differential

466

1,756

Elimination of inter-entity interest on partner loan

9,884

9,275

Income from unconsolidated joint ventures

11,721

7,976

Unconsolidated Joint Ventures [Member]

Schedule of Equity Method Investments [Line Items]

Straight-line rent adjustments

4,300

4,100

"Above" and "below" market rent adjustments, net

$ 25,300

$ 29,500

[1]	Includes straight-line rent adjustments of $4.3 million and $4.1 million for the three months ended March 31, 2012 and 2011, respectively. Includes net "below-" market rent adjustments of $25.3 million and $29.5 million for the three months ended March 31, 2012 and 2011, respectively.

Mortgage Notes Payable (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended
	Mar. 12, 2012	Mar. 31, 2012	Mar. 31, 2011
Mortgage Notes Payable [Line Items]
Discontinued operations gain		$ 18,361
Repayments of mortgage notes payable		150,519	$ 8,777
Gains from early extinguishments of debt		$ 767
Bay Colony Corporate Center [Member]
Mortgage Notes Payable [Line Items]
Interest at a fixed rate	6.53%
Maturity date		Jun. 11, 2012
Repayments of mortgage notes payable	$ 143,900
Penalty for early repayment of debt	0
Gains from early extinguishments of debt	$ 900
Montvale Center [Member]
Mortgage Notes Payable [Line Items]
Debt default, accrued interest rate		9.93%
Amount of debt extinguished		$ 25,000
Maturity date		Jun. 06, 2012
Discontinued operations gain		$ 18,361
Gains from early extinguishments of debt		$ 18,400

Unsecured Exchangeable Senior Notes (Narrative) (Details) - 2.875% Exchangeable Senior Notes [Member] - USD ($)				3 Months Ended
	Feb. 20, 2012	Feb. 16, 2012	Feb. 15, 2012	Mar. 31, 2012	Jan. 10, 2012
Debt Instrument [Line Items]
Coupon/Stated Rate					2.875%
Debt instrument repurchase date by company				Feb. 15, 2012
Put Right expiration date				Feb. 08, 2012
Notes redemption date				Feb. 20, 2012
Debt instrument in connection with redemption last day to exchange notes				Feb. 16, 2012
Debt instrument redemption price percentage of principal	100.00%	100.00%
Amount paid for repurchase	$ 333,459,000		$ 242,735,000

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

3 Months Ended

12 Months Ended

Dec. 17, 2007

$ / shares

Mar. 31, 2012

USD ($)

$ / shares

Dec. 31, 2007

USD ($)

$ / shares

Dec. 31, 2011

USD ($)

Aug. 13, 2008

$ / shares

Debt Instrument [Line Items]

Principal Amount

$ 1,197,500,000

Net unamortized discount

(2,720,000)

$ (3,462,000)

Adjustment for the equity component allocation, net of accumulated amortization

(46,283,000)

Total Principal Amount

$ 1,148,497,000

$ 1,715,685,000

3.625% Exchangeable Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

3.625%

Effective Rate

^[1]

4.037%

Exchange Rate

^[2]

8.5051

Principal Amount

$ 747,500,000

Maturity Date

Feb. 15, 2014

Initial exchange on principal amount of note

$ 1,000

Initial exchange price per share | $ / shares

$ 117.58

Revised exchange price due to capped call transaction | $ / shares

137.17

Effective exchange price | $ / shares

135.14

Premium over closing price

40.00%

Closing price per share of common stock | $ / shares

$ 97.98

Net cost of capped call transaction

$ 44,400,000

Initial exchange rate

8.5051

3.750% Exchangeable Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

3.75%

Effective Rate

^[1]

3.787%

Exchange Rate

^[3]

10.0066

Principal Amount

$ 450,000,000

First optional redemption date

^[4]

May 18, 2013

Maturity Date

May 15, 2036

Initial exchange on principal amount of note

$ 1,000

Special distribution per share common stock | $ / shares

$ 5.98

Initial exchange rate

9.3900

Revised exchange rate

10.0066

Revised exchange price resulting from special distribution | $ / shares

$ 99.93

Repurchase price for the notes

100.00%

[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.
[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 adjustment), 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. As of March 31, 2012, the effective exchange price was $135.14 per share.
[3]	In connection with the special distribution of $5.98 per share of Boston Properties, Inc.'s common stock declared on December 17, 2007, the exchange rate was adjusted from 9.3900 to 10.0066 shares per $1,000 principal amount of notes effective as of December 31, 2007, resulting in an exchange price of approximately $99.93 per share of Boston Properties, Inc.'s common stock.
[4]	Holders may require the Company to repurchase the notes for cash on May 18, 2013 and May 15, 2016, 2021, 2026 and 2031 and at any time prior to their maturity upon a fundamental change, in each case at a price equal to 100% of the principal amount of the notes being repurchased plus any accrued and unpaid interest up to, but excluding, the repurchase date.

Commitments And Contingencies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2010
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations	$ 16.3
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	15.00%
Deductible in insurance as a percentage of the value of the affected property, San Francisco	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
Operating partnership guarantee to cover liabilities of IXP	20.0
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation	13.5
Coverage for acts of Terrorism certified under TRIA in excess of amount provided by NYIXP, LLC, as a direct insurer	1,375.0
Property insurance program per occurrence limits	1,625.0
Coverage for acts of terrorism certified under TRIA in excess	250.0
125 West 55th Street Venture LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation	0.5	$ 21.3
Cash deposit into the escrow account		10.0
Escrow account remaining funding obligation		$ 11.3
601 Lexington Avenue [Member]
Commitments And Contingencies [Line Items]
Coverage for acts of Terrorism certified under TRIA in excess of amount provided by NYIXP, LLC, as a direct insurer	250.0
One Freedom Square [Member]
Commitments And Contingencies [Line Items]
Guarantee obligation related to tenant re-leasing costs	$ 7.9

Noncontrolling Interests (Narrative) (Details)	Mar. 31, 2012 shares
Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Operating Partnership (OP) Units	16,527,994
Long-Term Incentive Plan (LTIP) Units	1,690,649
Series Two Preferred Units	1,030,748
Convertible Operating Partnership (OP) Units	1,352,688
OPP Units Two Thousand And Eleven [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units	400,000
OPP Units Two Thousand And Twelve [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units	400,000

Noncontrolling Interests (Redeemable Preferred Units) (Narrative) (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2012 USD ($) $ / shares shares	Feb. 15, 2012 $ / shares	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Series Two Preferred Units	1,030,748
Series Two Preferred Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Units converted	82,296
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	1,030,748
Liquidation preference percentage	6.00%
Preferred Units liquidation preference \| $ / shares	$ 50.00
Operating Units liquidation preference \| $ / shares	$ 38.10
OP Units for each Preferred Unit	1.312336
Distributions to Series Two Preferred Units \| $ / shares		$ 0.75616
Number of holders exercising redemption rights	0		0	0	0
Closing price of common stock \| $ / shares	$ 104.99
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Units converted	108,000
Value of Series Two Preferred Units assuming conversion \| $	$ 142.0
Redemption Year Two Thousand Thirteen [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Maximum redeemable Preferred Units	1,007,662
Dates Series Two Preferred holders can require Operating Partnership to redeem their units for cash	May 14, 2013
Series Two Preferred Units redemption price per unit \| $ / shares	$ 50.00
Maximum portion that may be required for redemption of total	0.166666666667
Redemption Year Two Thousand Fourteen [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Maximum redeemable Preferred Units	1,007,662
Dates Series Two Preferred holders can require Operating Partnership to redeem their units for cash	May 12, 2014
Series Two Preferred Units redemption price per unit \| $ / shares	$ 50.00
Maximum portion that may be required for redemption of total	0.166666666667

Noncontrolling Interests (Common Units) (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2012	Mar. 16, 2012	Jan. 27, 2012
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption	199,526
Redemption of OP units issued on conversion of LTIP Units	54,472
Redemption of OP units issued on conversion of Series Two Preferred Units	108,000
Outperformance Awards LTIP Units distribution as percentage of OP Unit distribution prior to measurement date	10.00%
Distributions made to OP and LTIP units per unit			$ 0.55
Distribution paid to outperformance awards, OPP Units			$ 0.055
Distribution declared to OP and LTIP units by Boston Properties, Inc.		$ 0.55
Distribution declared to outperformance awards OPP Units by Boston Properties, Inc.		$ 0.055
Restriction on redemption of OP Unit to Common Stock, years	1
Redemption of OP Unit equivalence to Common Stock	1
Common units of operating partnership if converted value	$ 1,910
OPP Units Two Thousand And Eleven [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units	400,000
OPP Units Two Thousand And Twelve [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units	400,000
Series Two Preferred Units [Member] \| Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Closing price of common stock	$ 104.99
Quarter 4 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date	Jan. 27, 2012
Holders of record date	December 31, 2011
Quarter 1 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividends declared date	Mar. 16, 2012
Quarter 1 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividends declared date	Mar. 16, 2012
Dividend payable date	Apr. 30, 2012
Holders of record date	March 30, 2012

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2012	Dec. 31, 2011
Noncontrolling Interests [Abstract]
Noncontrolling interests in property partnerships	$ (1,267)	$ (1,063)

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

3 Months Ended

Mar. 31, 2012

Mar. 31, 2011

Noncontrolling Interests [Abstract]

Beginning Balance

$ 145,484

$ 125,765

Net income

801

823

Distributions

(801)

(823)

Reallocation of partnership interest

(3,465)

^[1]

12,781

Ending Balance

$ 142,019

$ 138,546

[1]	Includes the conversion of 82,296 Series Two Preferred Units into 108,000 OP Units during the three months ended March 31, 2012.

- Definition

The carrying value (book value) of an entity's issued and outstanding stock which is not included within permanent equity in Stockholders Equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

+ References + Details

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

3 Months Ended

Mar. 31, 2012

Mar. 31, 2011

Noncontrolling Interest [Line Items]

Conversion of redeemable partnership units

$ (3,465)

^[1]

$ 12,781

Noncontrolling Interests [Member]

Noncontrolling Interest [Line Items]

Beginning Balance

1,809,119

1,801,592

Contributions

24,443

22,803

Net income

8,031

6,029

Distributions

(10,064)

(10,078)

Conversion of redeemable partnership units

(6,026)

(29,216)

Unearned compensation

(14,857)

(13,558)

Accumulated other comprehensive loss

Adjustments to reflect redeemable partnership units at redemption value

102,060

124,201

Ending Balance

$ 1,912,775

$ 1,901,853

[1]	Includes the conversion of 82,296 Series Two Preferred Units into 108,000 OP Units during the three months ended March 31, 2012.

Noncontrolling Interests (Noncontrolling Interests-Property Partnerships) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Noncontrolling Interest [Line Items]
Beginning balance	$ (1,063)
Net income	546	$ 529
Ending balance	(1,267)
Property Partnerships [Member]
Noncontrolling Interest [Line Items]
Beginning balance	(1,063)	(614)
Net income	546	529
Distributions	(750)	(500)
Ending balance	$ (1,267)	$ (585)

- Definition

Amount of net Income or Loss for the period allocated to noncontrolling partners of a limited partnership included in the entity's consolidated financial statements.

+ References + Details

Partners' Capital (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended
	May 08, 2012	Jan. 27, 2012	May 08, 2012	Mar. 31, 2012	Mar. 31, 2011	Mar. 16, 2012	Dec. 31, 2011
Class of Stock [Line Items]
General partnership units				1,676,030			1,662,715
Limited partnership units				147,708,311			146,444,896
Dividend paid on common stock		$ 0.55
Dividends payable, amount per share						$ 0.55
At the market stock offering program, net proceeds				$ 109,330	$ 345,369
Shares of its Common Stock in connection with the redemption of an equal number of OP Units				199,526
Shares of Common Stock upon the exercise of options to purchase Common Stock by certain employees				17,706
Atm Program [Member]
Class of Stock [Line Items]
At the market stock offering program, shares issued	643,600		643,600	1,048,800
At the market stock offering program remaining amount available for issuance	$ 376,200			$ 444,600
At the market stock offering program, aggregate value of common stock				600,000
At the market stock offering program, gross proceeds			$ 68,400	110,500
At the market stock offering program, net proceeds			$ 67,700	$ 109,300
Quarter 4 [Member]
Class of Stock [Line Items]
Dividend shareholder of record date				Dec. 31, 2011
Quarter 4 [Member] \| OP Units [Member]
Class of Stock [Line Items]
Dividend payable date				Jan. 27, 2012
Quarter 1 [Member]
Class of Stock [Line Items]
Dividend shareholder of record date				Mar. 30, 2012
Dividends payable, date declared				Mar. 16, 2012
Quarter 1 [Member] \| OP Units [Member]
Class of Stock [Line Items]
Dividends payable, date declared				Mar. 16, 2012
Dividend payable date				Apr. 30, 2012

Earnings Per Common Unit (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2012 USD ($) $ / shares shares	Mar. 31, 2011 USD ($) $ / shares shares
Income from continuing operations attributable to Boston Properties Limited Partnership, Income (Numerator) \| $	$ 57,066	$ 49,394
Income from continuing operations attributable to Boston Properties Limited Partnership, Per Unit Amount \| $ / shares	$ 0.34	$ 0.30
Discontinued operations attributable to Boston Properties Limited Partnership, Income (Numerator) \| $	$ 18,205	$ (497)
Discontinued operations attributable to Boston Properties Limited Partnership, Per Unit Amount \| $ / shares	$ 0.11	$ 0.00
Net income attributable to Boston Properties, Limited Partnership \| $	$ 75,271	$ 48,897
Net income attributable to Boston Properties Limited Partnership, Units (Denominator) \| shares	166,060,000	162,082,000
Net income attributable to Boston Properties Limited Partnership, Per Unit Amount \| $ / shares	$ 0.45	$ 0.30
Stock Based Compensation and Exchangeable Senior Notes, Income (Numerator) \| $
Stock Based Compensation and Exchangeable Senior Notes, Units (Denominator) \| shares	403,000	409,000
Stock Based Compensation and Exchangeable Senior Notes, Per Unit Amount \| $ / shares	0.00	0.00
Diluted Earnings: Net income, Income (Numerator) \| $	$ 75,271	$ 48,897
Diluted Earnings: Net income, Units (Denominator) \| shares	166,463,000	162,491,000
Diluted Earnings: Net income, Per Unit Amount \| $ / shares	$ 0.45	$ 0.30
Redeemable common units \| shares	17,717,000	19,987,000
OPP Units Two Thousand And Eleven [Member]
OPP units included in earnings per share calculation \| shares	129,000

Stock Option And Incentive Plan (Narrative) (Details)				3 Months Ended	12 Months Ended
Stock Option And Incentive Plan (Narrative) (Details)	Feb. 13, 2012 USD ($) mo $ / shares yr shares	Feb. 07, 2012 $ / shares d	Jan. 25, 2012 yr	Mar. 31, 2012 USD ($) d yr	Dec. 31, 2011
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
LTIP And Common Units Equivalency Ratio				one-for-one
TRS Component Sliding Scale One [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
TRS measurement, years				3
Cumulative absolute TRS hurdle				24.00%
Percentage of the potential relative TRS component earned if the Company's TRS is equal to or greater than a cumulative 24% over three years				100.00%
TRS Component Sliding Scale Two [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Cumulative absolute TRS hurdle, annum				0.00%
Percentage earned if the Company's TRS is 0% or less				0.00%
TRS Component Sliding Scale Three [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
TRS measurement, years				3
Percentage calculated by linear interpolation earned if the Company's cumulative TRS over three years is between 0% and 24%, minimum				0.00%
Percentage calculated by linear interpolation earned if the Company's cumulative TRS over three years is between 0% and 24%, maximum				100.00%
TRS Component Hypothetical Situation [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
TRS measurement, years				3
Cumulative absolute TRS hurdle				18.00%
Cumulative absolute TRS hurdle, annum				6.00%
Potential relative TRS component proration percentage				75.00%
OPP Units Two Thousand And Eight [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
TRS measurement, years					3
OPP Units Two Thousand And Twelve [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Award additional vesting period, years			2
Measurement Period For Outperformance Awards				February 7, 2012 to February 6, 2015
Start of the measurement period				Feb. 07, 2012
End of the measurement period				Feb. 06, 2015
Trading days prior to and including February 7, 2012 \| d		5
TRS measurement, years			3
Average closing price of common stock for five trading days prior and including February 7, 2012 \| $ / shares		$ 106.69
Aggregate rewards of OPP awards, maximum cap \| $				$ 40,000,000
Excess total return above a cumulative absolute TRS hurdle				2.00%
Cumulative absolute TRS hurdle				24.00%
Cumulative absolute TRS hurdle, annum				8.00%
Measurement period for cumulative absolute TRS hurdle (years)				3
Excess or deficient total return of relative TRS hurdle equal to total return of REIT Index				2.00%
Distributions percent before measurement date				10.00%
Performance measurement period, days \| d				15
OPP Awards Vesting 2015 [Member] \| OPP Units Two Thousand And Twelve [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Vesting Percentage				25.00%
Vesting Date				Feb. 07, 2015
OPP Awards Vesting 2016 [Member] \| OPP Units Two Thousand And Twelve [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Vesting Percentage				25.00%
Vesting Date				Feb. 07, 2016
Opp Awards Vesting 2017 [Member] \| OPP Units Two Thousand And Twelve [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Vesting Percentage				50.00%
Vesting Date				Feb. 07, 2017
Minimum [Member] \| TRS Component Sliding Scale Three [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Cumulative absolute TRS hurdle				0.00%
Maximum [Member] \| TRS Component Sliding Scale Three [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Cumulative absolute TRS hurdle				24.00%
Executive Vice President [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Cash payment related to resignation \| $	$ 1,533,333
Cash bonus for 2011 as part of resignation agreement \| $	$ 950,000
Consulting period, months \| mo	2
Consulting fee, per month \| $	$ 20,000
Accelerated share vesting with respect to LTIP units \| shares	23,502
Common shares received due to accelerated share vesting with respect to stock options \| shares	4,464
Accelerated share vesting with respect to common stock \| shares	5,117
Common stock exercise price per share for stock options \| $ / shares	$ 92.71
Common stock exercise price per share for common stock \| $ / shares	$ 104.47
Non-compete agreement, years	1
Expense recognized upon resignation \| $				$ 4,500,000
2011 Outperformance Award [Member] \| Executive Vice President [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Percentage of outperformance award retained	36.00%

Stock Option And Incentive Plan (Restricted Stock) (Narrative) (Details)	3 Months Ended		65 Months Ended
	Mar. 31, 2012 USD ($) yr $ / shares shares	Mar. 31, 2011 USD ($)	Mar. 31, 2012 USD ($) $ / shares shares
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Stock-based compensation associated with restricted stock, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units	$ 10,900,000	$ 11,600,000
Accelerated Compensation Expenses Related To 2008 Opp Units		$ 4,300,000
Weighted-average period (years) \| yr	3.0
Restricted Stock [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Shares issued \| shares	19,521		19,521
Employee and director payment per share \| $ / shares	0.01
Value of shares of common stock	$ 2,100,000		$ 2,100,000
Employee's weighted average cost per share \| $ / shares	$ 107.57		$ 107.57
LTIP Units [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
LTIP units issued \| shares	169,301		169,301
Value of LTIP units issued	$ 16,800,000
Per unit fair value weighted-average \| $ / shares	$ 98.94		$ 98.94
Expected life assumed to calculate per unit fair value per LTIP unit (years) \| yr	5.8
Risk-free rate	0.94%
Expected price volatility	29.10%
LTIPs And Restricted Stock [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Vesting annual installments			4
Unrecognized compensation expenses	$ 34,400,000		$ 34,400,000
LTIPs and OPP Awards [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Employee and director payment per share \| $ / shares	0.25
OPP Units Two Thousand And Twelve [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
2012 OPP units issued \| shares	400,000		400,000
Risk-free rate	0.35%
Expected price volatility	31.00%
Value of OPP units	$ 7,700,000		$ 7,700,000
Method of valuation	The Monte Carlo simulation used a statistical formula underlying the Black-Scholes and binomial formulas and such simulation was run approximately 100,000 times.
Estimated dividend payments, per share	$ 7.28
OPP Units Two Thousand And Twelve [Member] \| SNL Equity REIT [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Expected price volatility	30.00%
Non Qualified Stock Options [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Non-qualified stock options issued \| shares	186,007		186,007
Expected life assumed to calculate per unit fair value per LTIP unit (years) \| yr	5.4
Risk-free rate	0.92%
Expected price volatility	28.40%
Expected dividend rate	2.90%
Method of valuation	The non-qualified stock options granted during the three months ended March 31, 2012 had a weighted-average fair value on the date of grant of $19.50 per option, which was computed using the Black-Scholes option-pricing model utilizing the following weighted-average assumptions: an expected life of 5.4 years, a risk-free interest rate of 0.92%, an expected price volatility of 28.4% and an expected dividend yield of 2.9%.
Weighted-average grant date fair value \| $ / shares	$ 19.50
Weighted-average exercise price \| $ / shares	$ 107.23		$ 107.23
Unvested 2011 and 2012 OPP Units [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Unrecognized compensation expenses	$ 11,400,000		$ 11,400,000
Executive Vice President [Member]
Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]
Stock-based compensation associated with restricted stock, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units	$ 2,700,000

Segment Reporting (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 415,905	$ 392,288
Rental Revenue: Office/Technical	12,311	11,550
Rental Revenue: Residential	4,481
Rental Revenue: Hotel	6,816	5,948
Rental Revenue: Total	$ 439,513	$ 409,786
Rental Revenue: % of Grand Totals	100.00%	100.00%
Rental Expenses: Class A Office	$ 151,210	$ 136,029
Rental Expenses: Office/Technical	3,581	3,601
Rental Expenses: Residential	2,715
Rental Expenses: Hotel	6,099	5,739
Rental Expenses: Total	$ 163,605	$ 145,369
Rental Expenses: % Of Grand Totals	100.00%	100.00%
Net Operating Income: % of Grand Totals	100.00%	100.00%
Boston [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 140,871	$ 127,429
Rental Revenue: Office/Technical	8,167	7,558
Rental Revenue: Residential	883
Rental Revenue: Hotel	6,816	5,948
Rental Revenue: Total	$ 156,737	$ 140,935
Rental Revenue: % of Grand Totals	35.66%	34.39%
Rental Expenses: Class A Office	$ 57,890	$ 47,901
Rental Expenses: Office/Technical	2,510	2,479
Rental Expenses: Residential	390
Rental Expenses: Hotel	6,099	5,739
Rental Expenses: Total	$ 66,889	$ 56,119
Rental Expenses: % Of Grand Totals	40.89%	38.61%
Net Operating Income	$ 89,848	$ 84,816
Net Operating Income: % of Grand Totals	32.56%	32.08%
New York [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 117,589	$ 113,007
Rental Revenue: Residential
Rental Revenue: Total	$ 117,589	$ 113,007
Rental Revenue: % of Grand Totals	26.75%	27.58%
Rental Expenses: Class A Office	$ 38,429	$ 37,715
Rental Expenses: Residential
Rental Expenses: Total	$ 38,429	$ 37,715
Rental Expenses: % Of Grand Totals	23.49%	25.94%
Net Operating Income	$ 79,160	$ 75,292
Net Operating Income: % of Grand Totals	28.69%	28.48%
Princeton [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 14,850	$ 16,279
Rental Revenue: Residential
Rental Revenue: Total	$ 14,850	$ 16,279
Rental Revenue: % of Grand Totals	3.38%	3.97%
Rental Expenses: Class A Office	$ 7,358	$ 7,915
Rental Expenses: Residential
Rental Expenses: Total	$ 7,358	$ 7,915
Rental Expenses: % Of Grand Totals	4.50%	5.44%
Net Operating Income	$ 7,492	$ 8,364
Net Operating Income: % of Grand Totals	2.72%	3.16%
San Francisco [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 52,197	$ 52,893
Rental Revenue: Office/Technical	52
Rental Revenue: Residential
Rental Revenue: Total	$ 52,249	$ 52,893
Rental Revenue: % of Grand Totals	11.89%	12.91%
Rental Expenses: Class A Office	$ 20,091	$ 19,333
Rental Expenses: Office/Technical	24
Rental Expenses: Residential
Rental Expenses: Total	$ 20,115	$ 19,333
Rental Expenses: % Of Grand Totals	12.29%	13.30%
Net Operating Income	$ 32,134	$ 33,560
Net Operating Income: % of Grand Totals	11.65%	12.69%
Washington, DC [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 90,398	$ 82,680
Rental Revenue: Office/Technical	4,092	3,992
Rental Revenue: Residential	3,598
Rental Revenue: Total	$ 98,088	$ 86,672
Rental Revenue: % of Grand Totals	22.32%	21.15%
Rental Expenses: Class A Office	$ 27,442	$ 23,165
Rental Expenses: Office/Technical	1,047	1,122
Rental Expenses: Residential	2,325
Rental Expenses: Total	$ 30,814	$ 24,287
Rental Expenses: % Of Grand Totals	18.83%	16.71%
Net Operating Income	$ 67,274	$ 62,385
Net Operating Income: % of Grand Totals	24.38%	23.59%
Segment, Continuing Operations [Member]
Segment Reporting Information [Line Items]
Net Operating Income	$ 275,908	$ 264,417

Segment Reporting (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Segment Reporting Information [Line Items]
Net operating income	$ 146,715	$ 139,948
Development and management services income	8,149	7,428
Income from unconsolidated joint ventures	11,721	7,976
Interest and other income	1,646	974
Gains from investments in securities	801	373
Gains from early extinguishments of debt	767
Gain on forgiveness of debt from discontinued operations	18,361
General and administrative expense	27,619	24,643
Transaction costs	2,104	72
Depreciation and amortization expense	107,619	107,182
Interest expense	103,237	98,525
Loss from discontinued operations	156	497
Noncontrolling interest in property partnerships	546	529
Noncontrolling interest-redeemable preferred units	801	823
Net income attributable to Boston Properties Limited Partnership	75,271	48,897
Business Intersegment, Eliminations [Member]
Segment Reporting Information [Line Items]
Net operating income	275,908	264,417
Development and management services income	8,149	7,428
Income from unconsolidated joint ventures	11,721	7,976
Interest and other income	1,646	974
Gains from investments in securities	801	373
Gains from early extinguishments of debt	767
Gain on forgiveness of debt from discontinued operations	18,361
General and administrative expense	27,619	24,643
Transaction costs	2,104	72
Depreciation and amortization expense	107,619	107,182
Interest expense	103,237	98,525
Loss from discontinued operations	156	497
Noncontrolling interest in property partnerships	546	529
Noncontrolling interest-redeemable preferred units	801	823
Net income attributable to Boston Properties Limited Partnership	$ 75,271	$ 48,897

Subsequent Events (Details)						1 Months Ended	3 Months Ended
Subsequent Events (Details)	May 08, 2012 USD ($) shares	May 03, 2012	May 01, 2012 USD ($)	Apr. 30, 2012	Apr. 02, 2012 USD ($)	May 08, 2012 USD ($) shares	Mar. 31, 2012 USD ($) shares	Mar. 31, 2011 USD ($)
Subsequent Event [Line Items]
At the market stock offering program, net proceeds							$ 109,330,000	$ 345,369,000
Repayments of mortgage notes payable							$ 150,519,000	$ 8,777,000
12310 Sunrise Valley Drive [Member]
Subsequent Event [Line Items]
Percentage of office component of the development project placed in-service		100.00%
Square footage of real estate property		268,000
510 Madison Avenue [Member]
Subsequent Event [Line Items]
Percentage of office component of the development project placed in-service				100.00%
Square footage of real estate property				347,000
Bedford Business Park [Member]
Subsequent Event [Line Items]
Disposition price			$ 62,800,000
Square footage of real estate property			470,000
Atm Program [Member]
Subsequent Event [Line Items]
Shares issued \| shares	643,600					643,600	1,048,800
At the market stock offering program, gross proceeds						$ 68,400,000	$ 110,500,000
At the market stock offering program, net proceeds						$ 67,700,000	109,300,000
At the market stock offering program remaining amount available for issuance	$ 376,200,000						$ 444,600,000
One Freedom Square [Member]
Subsequent Event [Line Items]
Repayments of mortgage notes payable					$ 65,100,000
Interest at a fixed rate					7.75%
Maturity date							Jun. 30, 2012
Penalty for early repayment of debt					$ 0
Office/Technical Properties [ Member] \| Bedford Business Park [Member]
Subsequent Event [Line Items]
Number of real estate properties			2
Class A Office Properties [ Member] \| Bedford Business Park [Member]
Subsequent Event [Line Items]
Number of real estate properties			1