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Document And Entity Information - shares	6 Months Ended
Document And Entity Information - shares	Jun. 30, 2012	Aug. 01, 2013
Document And Entity Information [Abstract]
Document Type	10-Q
Document Period End Date	Jun. 30, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Entity Registrant Name	BOSTON PROPERTIES INC
Amendment Flag	false
Entity Central Index Key	0001037540
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		152,388,954

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
ASSETS
Real estate, at cost	$ 17,059,235	$ 13,581,454
Construction in progress	1,483,114	1,036,780
Land held for future development	290,085	275,094
Less: accumulated depreciation	(2,996,520)	(2,934,160)
Total real estate	15,835,914	11,959,168
Cash and cash equivalents	1,608,731	1,041,978
Cash held in escrows	54,829	55,181
Investments in securities	14,226	12,172
Tenant and other receivables (net of allowance for doubtful accounts of $1,377 and $1,960, respectively)	66,039	69,555
Related party notes receivable	0	282,491
Interest receivable from related party notes receivable	0	104,816
Accrued rental income (net of allowance of $3,641 and $1,653, respectively)	625,654	598,199
Deferred charges, net	939,675	588,235
Prepaid expenses and other assets	179,741	90,610
Investments in unconsolidated joint ventures	137,975	659,916
Total assets	19,462,784	15,462,321
Liabilities:
Mortgage notes payable	4,484,657	3,102,485
Unsecured senior notes (net of discount of $15,027 and $10,472, respectively)	5,834,973	4,639,528
Unsecured exchangeable senior notes (net of discount of $924 and $1,653, respectively)	734,278	1,170,356
Unsecured line of credit	0	0
Mezzanine notes payable	311,637	0
Related party notes payable	180,000	0
Accounts payable and accrued expenses	212,998	199,102
Dividends and distributions payable	112,425	110,488
Accrued interest payable	141,676	72,461
Other liabilities	556,730	324,613
Total liabilities	12,569,374	9,619,033
Commitments and contingencies	0	0
Noncontrolling interest:
Redeemable preferred units of the Operating Partnership	110,876	110,876
Redeemable interest in property partnerships	98,162	97,558
Equity:
Excess stock, $.01 par value, 150,000,000 shares authorized, none issued or outstanding	0	0
Preferred stock, $.01 par value, 50,000,000 shares authorized
5.25% Series B cumulative redeemable preferred stock, $.01 par value, liquidation preference of $2,500 per share, 92,000 shares authorized, 80,000 and no shares issued and outstanding at June 30, 2013 and December 31,2012, respectively	200,000	0
Common stock, $.01 par value, 250,000,000 shares authorized, 152,463,640 and 151,680,109 issued and 152,384,740 and 151,601,209 outstanding at June 30, 2013 and December 31, 2012, respectively	1,524	1,516
Additional paid-in capital	5,246,243	5,222,073
Dividends in excess of earnings	192,492	(109,985)
Treasury common stock at cost, 78,900 shares at June 30, 2013 and December 31, 2012	(2,722)	(2,722)
Accumulated other comprehensive loss	(12,689)	(13,817)
Total stockholders' equity attributable to Boston Properties, Inc.	5,624,848	5,097,065
Noncontrolling interests:
Common units of the Operating Partnership	570,135	539,753
Property partnerships	489,389	(1,964)
Total equity	6,684,372	5,634,854
Total liabilities and equity	$ 19,462,784	$ 15,462,321

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Tenant and other receivables, allowance for doubtful accounts	$ 1,377	$ 1,960
Accrued rental income, allowance	3,641	1,571
Unsecured senior notes, discount	15,027	10,472
Unsecured exchangeable senior notes, discount	$ 924	$ 1,653
Excess stock, par value	$ 0.01	$ 0.01
Excess stock, shares authorized	150,000,000	150,000,000
Excess stock, shares issued	0	0
Excess stock, shares outstanding	0	0
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	152,463,640	151,680,119
Common stock, shares outstanding	152,384,740	151,601,209
Treasury common stock at cost, shares	78,900	78,900
Series B Cumulative Redeemable Preferred Stock [Member]
Preferred stock, par value	$ 0.01	$ 0
Preferred stock, shares authorized	92,000	0
Series B Dividend Rate Percentage	5.25%	0.00%
Series B, Liquidation Preference Per Share	$ 2,500.00	$ 0
Series B, shares issued	80,000	0
Series B, Shares Outstanding	80,000	0

Consolidated Statements Of Operations - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue
Base rent	$ 403,942,000	$ 371,019,000	$ 781,670,000	$ 725,844,000
Recoveries from tenants	68,434,000	57,361,000	132,863,000	109,009,000
Parking and other	23,969,000	23,356,000	47,799,000	45,615,000
Total rental revenue	496,345,000	451,736,000	962,332,000	880,468,000
Hotel revenue	11,118,000	10,049,000	19,409,000	16,865,000
Development and management services	7,857,000	9,564,000	16,593,000	17,709,000
Total revenue	515,320,000	471,349,000	998,334,000	915,042,000
Expenses
Rental	179,837,000	161,172,000	352,457,000	317,014,000
Hotel	7,335,000	6,616,000	14,379,000	12,715,000
General and administrative	22,194,000	19,066,000	65,765,000	46,685,000
Transaction costs	535,000	8,000	978,000	2,112,000
Impairment loss	0	0	8,306,000	0
Depreciation and amortization	134,604,000	111,168,000	255,199,000	219,630,000
Total expenses	344,505,000	298,030,000	697,084,000	598,156,000
Operating income	170,815,000	173,319,000	301,250,000	316,886,000
Other income (expense)
Income from unconsolidated joint ventures	48,783,000	21,191,000	57,504,000	32,912,000
Gain on consolidation of joint ventures	387,801,000	0	387,801,000	0
Interest and other income	1,296,000	2,382,000	2,767,000	4,028,000
Gains (losses) from investments in securities	181,000	(186,000)	916,000	615,000
Gains from early extinguishments of debt	152,000	274,000	152,000	1,041,000
Interest expense	(103,140,000)	(99,901,000)	(203,573,000)	(203,138,000)
Income from continuing operations	505,888,000	97,079,000	546,817,000	152,344,000
Discontinued operations
Income from discontinued operations	873,000	218,000	934,000	788,000
Gain on sale of real estate from discontinued operations	0	36,877,000	0	36,877,000
Gain on forgiveness of debt from discontinued operations	0	0	20,182,000	0
Impairment loss from discontinued operations	0	0	(3,241,000)	0
Net income	506,761,000	134,174,000	564,692,000	190,009,000
Net income attributable to noncontrolling interests
Noncontrolling interests in property partnerships	219,000	(457,000)	(2,355,000)	(1,003,000)
Noncontrolling interest - redeemable preferred units of the Operating Partnership	(1,123,000)	(765,000)	(2,303,000)	(1,566,000)
Noncontrolling interest - common units of the Operating Partnership	(50,734,000)	(10,318,000)	(55,277,000)	(16,310,000)
Noncontrolling interest in discontinued operations - common units of the Operating Partnership	(88,000)	(4,075,000)	(1,900,000)	(4,159,000)
Net income attributable to Boston Properties, Inc.	455,035,000	118,559,000	502,857,000	166,971,000
Preferred dividends	(2,618,000)	0	(2,764,000)	0
Net income attributable to Boston Properties, Inc. common shareholders	$ 452,417,000	$ 118,559,000	$ 500,093,000	$ 166,971,000
Basic earnings per common share attributable to Boston Properties, Inc.:
Income from continuing operations (in dollars per share)	$ 2.94	$ 0.57	$ 3.17	$ 0.89
Discontinued operations (in dollars per share)	0.01	0.22	0.10	0.23
Net income (in dollars per share)	$ 2.95	$ 0.79	$ 3.27	$ 1.12
Weighted average number of common shares outstanding (in shares)	151,938	150,312	151,793	149,328
Diluted earnings per common share attributable to Boston Properties, Inc.:
Income from continuing operations (in dollars per share)	$ 2.93	$ 0.56	$ 3.16	$ 0.89
Discontinued operations (in dollars per share)	0.01	0.22	0.10	0.23
Diluted Earnings: Net income, Per Share Amount (in dollars per share)	$ 2.94	$ 0.78	$ 3.26	$ 1.12
Weighted average number of common and common equivalent shares outstanding (in shares)	152,490	150,694	152,222	149,720

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

3 Months Ended

6 Months Ended

Jun. 30, 2013

Jun. 30, 2012

Jun. 30, 2013

Jun. 30, 2012

Statement of Comprehensive Income [Abstract]

Net income

$ 506,761

$ 134,174

$ 564,692

$ 190,009

Other comprehensive income:

Amortization of interest rate contracts

^[1]

627

648

1,255

1,297

Other Comprehensive Income

627

648

1,255

1,297

Comprehensive income

507,388

134,822

565,947

191,306

Net income attributable to noncontrolling interests

(51,726)

(15,615)

(61,835)

(23,038)

Other comprehensive income attributable to noncontrolling interest

(63)

(68)

(127)

(137)

Comprehensive income attributable to Boston Properties, Inc.

$ 455,599

$ 119,139

$ 503,985

$ 168,131

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

Consolidated Statements Of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-In Capital [Member]	Dividends In Excess Of Earnings [Member]	Treasury Stock, At Cost [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
Equity, value at Dec. 31, 2011	$ 5,413,516	$ 1,481		$ 4,936,457	$ (53,080)	$ (2,722)	$ (16,138)	$ 547,518
Equity, shares at Dec. 31, 2011		148,108,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units to Common Stock, shares		227,000
Conversion of operating partnership units to Common Stock, value	0	$ 2		6,829				(6,831)
Conversion of redeemable preferred units to common units	4,115							4,115
Allocated net income for the year	188,443				166,971			21,472
Dividends/distributions declared					(165,055)
Sale of common stock, net of offering costs		2,348,000
Sale of common stock, net of offering costs	247,186	$ 24		247,162
Shares issued in connection with exchange of Exchangeable Senior Notes, value	0
Shares issued pursuant to stock purchase plan, shares		4,000
Shares issued pursuant to stock purchase plan, value	381			381
Net activity from stock option and incentive plan, shares		29,000
Net activity from stock option and incentive plan, value	18,705			4,032				14,673
Noncontrolling interests in property partnerships recorded upon consolidation	0
Distributions to noncontrolling interests in property partnerships	(1,500)							(1,500)
Amortization of interest rate contracts	1,297						1,160	137
Reallocation of noncontrolling interest				(10,178)				10,178
Equity, value at Jun. 30, 2012	5,686,988	$ 1,507		5,184,683	(51,164)	(2,722)	(14,978)	569,662
Equity, shares at Jun. 30, 2012		150,716,000
Equity, value at Dec. 31, 2012	$ 5,634,854	$ 1,516	$ 0	5,222,073	(109,985)	(2,722)	(13,817)	537,789
Equity, shares at Dec. 31, 2012	151,601,209	151,601,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units to Common Stock, shares		334,000
Conversion of operating partnership units to Common Stock, value	$ 0	$ 4		10,305				(10,309)
Allocated net income for the year	558,835				502,857			55,978
Dividends/distributions declared	(223,085)				(200,380)			(22,705)
Issuance of 5.25% Series B cumulative redeemable preferred stock	193,920		200,000
Shares issued in connection with exchange of Exchangeable Senior Notes, shares		419,000
Shares issued in connection with exchange of Exchangeable Senior Notes, value	43,834	$ 4		43,830
Equity component of exchange of Exchangeable Senior Notes				(43,869)
Issuance of 5.25% Series B cumulative redeemable preferred stock				(6,080)
Shares issued pursuant to stock purchase plan, shares		3,000
Shares issued pursuant to stock purchase plan, value	335			335
Net activity from stock option and incentive plan, shares		28,000
Net activity from stock option and incentive plan, value	25,741			5,353				20,388
Noncontrolling interests in property partnerships recorded upon consolidation	483,488							483,488
Contributions from noncontrolling interests in property partnerships	10,564							10,564
Distributions to noncontrolling interests in property partnerships	(1,500)							(1,500)
Amortization of interest rate contracts	1,255						1,128	127
Reallocation of noncontrolling interest	0			14,296				(14,296)
Equity, value at Jun. 30, 2013	$ 6,684,372	$ 1,524	$ 200,000	$ 5,246,243	$ 192,492	$ (2,722)	$ (12,689)	$ 1,059,524
Equity, shares at Jun. 30, 2013	152,384,740	152,385,000

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 564,692	$ 190,009
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	255,795	221,940
Non-cash compensation expense	32,464	18,113
Impairment loss	8,306	0
Income from unconsolidated joint ventures	(57,504)	(32,912)
Gain on Consolidation of Joint Ventures	(387,801)	0
Distributions of net cash flow from operations of unconsolidated joint ventures	25,689	20,190
Gains from investments in securities	(916)	(615)
Non-cash portion of interest expense	20,120	21,893
Settlement of accreted debt discount on repurchases of unsecured exchangeable senior notes	(56,532)	(68,760)
Gains from early extinguishments of debt	(264)	(1,196)
Gain (Loss) on Disposition of Real Estate, Discontinued Operations	0	(36,877)
Gain on forgiveness of debt from discontinued operations	(20,182)	0
Impairment loss from discontinued operations	3,241	0
Change in assets and liabilities:
Cash held in escrows	2,687	8,067
Tenant and other receivables, net	(7,018)	30,120
Accrued rental income, net	(29,127)	(39,524)
Prepaid expenses and other assets	17,708	38,703
Accounts payable and accrued expenses	1,399	(2,710)
Accrued interest payable	2,022	(3,917)
Other liabilities	(20,086)	(7,589)
Tenant leasing costs	(19,855)	(23,855)
Total adjustments	(229,854)	141,071
Net cash provided by operating activities	334,838	331,080
Cash flows from investing activities:
Acquisitions of real estate	(522,900)	(621,359)
Construction in progress	(181,056)	(152,548)
Building and other capital improvements	(23,681)	(21,569)
Tenant improvements	(55,988)	(72,786)
Proceeds from the sales of real estate	39,320	61,963
Cash recorded upon consolidation	79,468	0
Issuance of notes receivable	12,491	(1,974)
Capital contributions to unconsolidated joint ventures	0	(325)
Capital distributions from unconsolidated joint ventures	201,182	3,057
Investments in securities, net	(1,138)	(873)
Net cash used in investing activities	(452,302)	(806,414)
Cash flows from financing activities:
Repayments of mortgage notes payable	(79,865)	(219,865)
Proceeds from unsecured senior notes	1,194,753	997,790
Redemption/repurchase of unsecured exchangeable senior notes	(393,468)	(507,434)
Deferred financing costs	(8,546)	(7,758)
Proceeds from Issuance of Preferred Stock and Preference Stock	193,920
Net proceeds from ATM stock issuances	0	247,186
Net proceeds from equity transactions	(694)	973
Dividends and distributions	(223,451)	(185,269)
Contributions from noncontrolling interest in property partnerships	6,018	0
Distributions to noncontrolling interest in property partnerships	(4,450)	(1,500)
Net cash provided by (sued in) financing activities	684,217	324,123
Net decrease in cash and cash equivalents	566,753	(151,211)
Cash and cash equivalents, beginning of period	1,041,978	1,823,208
Cash and cash equivalents, end of period	1,608,731	1,671,997
Supplemental disclosures:
Cash paid for interest	271,177	276,494
Interest capitalized	32,854	21,278
Non-cash investing and financing activities:
Additions to real estate included in accounts payable and accrued expenses	4,746	3,225
Real estate and realted intangibles recorded upon consolidation	3,356,000	0
Debt recorded upon consolidation	2,056,000	0
Working capital recorded upon consolidation	91,280	0
Noncontrolling interest recorded upon consolidation	483,488	0
investment in unconsolidated joint venture elminated upon consolidation	361,808	0
Mortgage note payable extinguished through foreclosure	25,000	0
Real estate transferred upon foreclosure	7,508	0
Land improvements contributed by noncontrolling property partnership	4,546	0
Dividends and distributions declared but not paid	112,425	93,353
issuance of common stock in connection with the exchange of exchangeable senior notes	43,834	0
Conversions of noncontrolling interests to stockholders' equity	10,309	6,831
Conversion of redeemable preferred units to common units	0	4,115
Issuance of restricted securities to employees and directors	$ 30,077	$ 25,955

Organization

6 Months Ended

Jun. 30, 2013

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization

Boston Properties, Inc. (the “Company”), a Delaware corporation, is a self-administered and self-managed real estate investment trust (“REIT”). The Company is the sole general partner of Boston Properties Limited Partnership (the “Operating Partnership”) and at June 30, 2013 owned an approximate 89.2% (88.5% at June 30, 2012) general and limited partnership interest in the Operating Partnership. Partnership interests in the Operating Partnership are denominated as “common units of partnership interest” (also referred to as “OP Units”), “long term incentive units of partnership interest” (also referred to as “LTIP Units”) or “preferred units of partnership interest” (also referred to as “Preferred Units”). In addition, in February 2011 and February 2012, the Company issued LTIP Units in connection with the granting to employees of outperformance awards (also referred to as “2011 OPP Units” and “2012 OPP Units,” respectively, and collectively as “OPP Units”). In February 2013, the Company issued LTIP Units in connection with the granting to employees of 2013 MYLTIP Units (“2013 MYLTIP Units”). Because the rights, preferences and privileges of OPP Units and 2013 MYLTIP Units differ from other LTIP Units granted to employees as part of the annual compensation process, unless specifically noted otherwise, all references to LTIP Units exclude OPP Units and 2013 MYLTIP Units (See Notes 9 and 12).

Unless specifically noted otherwise, all references to OP Units exclude units held by the Company. A holder of an OP Unit may present such OP Unit to the Operating Partnership 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 Operating Partnership is obligated to redeem such OP Unit for cash equal to the value of a share of common stock of the Company (“Common Stock”) at such time. In lieu of a cash redemption, the Company 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 the Company 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 the Company. 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 10).

At June 30, 2013, there were three series of Preferred Units outstanding (i.e., Series Two Preferred Units, Series Four Preferred Units and Series B Preferred Units). The Series Two Preferred Units bear a distribution that is set in accordance with an amendment to the partnership agreement of the Operating Partnership. Each Series Two Preferred Unit may also be converted into approximately 1.312336 OP Units or redeemed for $50.00 of cash at the election of the holder thereof or the Operating Partnership in accordance with the terms and conditions set forth in the applicable amendment to the partnership agreement. The Series Four Preferred Units are not convertible into or exchangeable for any common equity of the Operating Partnership or the Company, have a per unit liquidation preference of $50.00 and are entitled to receive quarterly distributions of $0.25 per unit (or an annual rate of 2.00%) (See Note 9). The Series B Preferred Units were issued to the Company on March 27, 2013 in connection with the Company's issuance of 80,000 shares (8,000,000 depositary shares each representing 1/100th of a share) of 5.25% Series B Cumulative Redeemable Preferred Stock (the "Series B Preferred Stock"). The Company contributed the net proceeds from the offering to the Operating Partnership in exchange for 80,000 Series B Preferred Units having terms and preferences generally mirroring those of the Series B Preferred Stock (See Note 10).

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

Properties

At June 30, 2013, the Company owned or had interests in a portfolio of 179 commercial real estate properties (the “Properties”) aggregating approximately 44.8 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 46,411 vehicles containing approximately 15.7 million square feet. At June 30, 2013, the Properties consist of:


•	171 office properties, including 131 Class A office properties (including seven properties under construction) and 40 Office/Technical properties;


•	one hotel;


•	four retail properties; and


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

The Company owns or controls undeveloped land parcels totaling approximately 512.8 acres.

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

- Definition

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

+ References

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+ Details

Basis Of Presentation And Summary Of Significant Accounting Policies

6 Months Ended

Jun. 30, 2013

Accounting Policies [Abstract]

Basis Of Presentation And Summary Of Significant Accounting Policies

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

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, 2012. 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 inputs used in determining the fair value of the Company’s unsecured senior notes and unsecured exchangeable senior notes is categorized at a level 1 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company uses quoted market rates to value these instruments. However, the inputs used in determining the fair value could be categorized at a level 2 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) if trading volumes are low. The Company determines the fair value of its mortgage notes payable using discounted cash flow analyses by discounting the spread between the future contractual interest payments and hypothetical future interest payments on mortgage debt based on current market rates for similar securities. In determining the current market rates, the Company adds its estimates of market spreads to the quoted yields on federal government treasury securities with similar maturity dates to its debt. The inputs used in determining the fair value of the Company’s mortgage notes payable are categorized at a level 3 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company considers the rates used in the valuation techniques to be unobservable inputs.

Because the Company’s valuations of its financial instruments are based on these types of estimates, the actual fair values of its financial instruments may differ materially if the Company’s estimates do not prove to be accurate. The following table presents the aggregate carrying value of the Company’s indebtedness and the Company’s corresponding estimate of fair value as of June 30, 2013 and December 31, 2012 (in thousands):



	June 30, 2013					December 31, 2012
	Carrying Amount			Estimated Fair Value		Carrying Amount			Estimated Fair Value
Mortgage notes payable	$	4,484,657		$	4,598,927	$	3,102,485		$	3,256,940
Mezzanine notes payable	311,637			311,665		—			—
Unsecured senior notes	5,834,973			6,093,237		4,639,528			5,162,486
Unsecured exchangeable senior notes	734,278		(1)	772,691		1,170,356		(1)	1,278,554
Total	$	11,365,545		$	11,776,520	$	8,912,369		$	9,697,980

_______________


(1)	Includes the net adjustment for the equity component allocation totaling approximately $12.3 million and $25.5 million at June 30, 2013 and December 31, 2012, respectively.

Out-of-Period Adjustment

During the six months ended June 30, 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 six months ended June 30, 2012 and in the understatement of real estate operating expenses in the aggregate amount of approximately $3.2 million in previous periods. Because this adjustment was not material to the prior years’ consolidated financial statements and the impact of recording the adjustment in the then-current period was not material to the Company’s consolidated financial statements, the Company recorded the related adjustment during the six months ended June 30, 2012.

Revision of Prior Period Amounts

The table below reflects selected information for the Company for the three and six months ended June 30, 2012. The servicer of the non-recourse mortgage loan in the amount of $25.0 million collateralized by the Company's Montvale Center property located in Gaithersburg, Maryland foreclosed on the property on January 31, 2012. As a result of the foreclosure, the Company recognized a gain on forgiveness of debt during the six months ended June 30, 2012 totaling approximately $17.8 million. Due to a procedural error of the trustee, the foreclosure sale was subsequently dismissed by the applicable court prior to ratification. As a result, the Company, as part of its 2012 Form 10-K filing, revised its financial statements to (1) properly reflect the property and related mortgage debt on its consolidated balance sheet at December 31, 2012, (2) reverse the gain on forgiveness of debt during the six months ended June 30, 2012 and (3) recognize the operating activity from the property for the three and six months ended June 30, 2012. On February 20, 2013, the subsequent foreclosure sale of Montvale Center was ratified by the court. As a result of the ratification, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate resulting in the recognition of a gain on forgiveness of debt totaling approximately $20.2 million during the six months ended June 30, 2013 (See Note 3). As a result, for the three and six months ended June 30, 2012, the activity for Montvale Center has been reclassified to discontinued operations in the consolidated statements of operations. In addition, operating results have been reclassified for the three and six months ended June 30, 2012 as a result of the discontinued operations presentation of (1) the Company's Bedford Business Park properties which were sold on May 17, 2012 and (2) the Company's 303 Almaden Boulevard property which was sold on June 28, 2013 (See Note 3).



	For the three months ended June 30, 2012				For the six months ended June 30, 2012
	As Reported		As Revised		As Reported		As Revised
	(in thousands, except for per share amounts)

Total revenue	$	472,897	$	471,349	$	918,124	$	915,042
Income from continuing operations	$	97,471	$	97,079	$	153,188	$	152,344
Discontinued operations	$	37,275	$	37,095	$	55,568	$	37,665
Net income attributable to Boston Properties, Inc. common shareholders	$	119,070	$	118,559	$	183,672	$	166,971
Income attributable to Boston Properties, Inc. common shareholders per share—basic	$	0.79	$	0.79	$	1.23	$	1.12
Income attributable to Boston Properties, Inc. common shareholders per share—diluted	$	0.79	$	0.78	$	1.23	$	1.12

Recent Accounting Pronouncements

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

Real Estate Activity During the Six Months Ended June 30, 2013

6 Months Ended

Jun. 30, 2013

Real Estate [Abstract]

Real Estate Activity During the Six Months Ended June 30, 2013

Acquisitions

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

On March 26, 2013, the consolidated joint venture in which the Company has a 95% interest completed the acquisition of a land parcel in San Francisco, California that will support a 60-story, 1.4 million square foot office tower known as Transbay Tower. The purchase price for the land was approximately $192.0 million. On February 7, 2013, the partner in the joint venture issued a notice that it was electing under the joint venture agreement to reduce its nominal ownership interest in the venture from 50% to 5%. On February 26, 2013, the Company issued a notice to the partner electing to proceed with the venture on that basis. As a result, the Company has a 95% nominal interest in and is consolidating the joint venture (See Note 9). The joint venture has commenced construction of the initial phase of the development consisting of building the project to grade.

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

On April 10, 2013, the Company acquired the Mountain View Research Park and Mountain View Technology Park properties from Boston Properties Office Value-Added Fund, L.P. (the "Value-Added Fund") for an aggregate gross purchase price of approximately $233.5 million. Mountain View Research Park is a 16-building complex of Office/Technical properties aggregating approximately 604,000 net rentable square feet. Mountain View Technology Park is a seven-building complex of Office/Technical properties aggregating approximately 135,000 net rentable square feet. The following table summarizes the allocation of the aggregate purchase price of Mountain View Research Park and Mountain View Technology Park at the date of acquisition (in thousands).



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

On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties. 767 Fifth Avenue (the General Motors Building) is a Class A office property totaling approximately 1.8 million net rentable square feet. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that, effective as of May 31, 2013, the Company accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting (See Notes 5 and 9). The following table summarizes the allocation of the aggregate purchase price of 767 Fifth Avenue (the General Motors Building) at the date of consolidation on May 31, 2013 (in thousands).



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

Working capital recorded upon consolidation
Cash and cash equivalents	$	79,468
Cash held in escrows	2,403
Tenant and other receivables	7,104
Prepaid expenses and other assets	4,269
Accounts payable and accrued expenses	(2,418		)
Accrued interest payable	(175,802		)	(2)
Other liabilities	(6,304		)
	$	(91,280	)

Noncontrolling interest recorded upon consolidation
Noncontrolling interests	$	(520,000	)
Noncontrolling interests - working capital	36,512
	$	(483,488	)

Net assets recorded upon consolidation	$	725,232

_______________

(1) The Company's partner loans totaling $270.0 million eliminates in consolidation.

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

Mountain View Research Park and Mountain View Technology Park contributed approximately $5.2 million of revenue and approximately $(0.3) million of earnings to the Company for the period from April 10, 2013 through June 30, 2013. 767 Fifth Avenue (the General Motors Building) contributed approximately $22.6 million of revenue and approximately $0.4 million of earnings to the Company for the period from May 31, 2013 through June 30, 2013.

The accompanying unaudited pro forma information for the six months ended June 30, 2013 and 2012 is presented as if the operating property acquisitions of (1) Mountain View Research Park and Mountain View Technology Park on April 10, 2013 and the approximately $24.4 million gain on consolidation and (2) 767 Fifth Avenue (the General Motors Building) on May 31, 2013 and the approximately $363.4 million gain on consolidation, had occurred on January 1, 2012. This unaudited pro forma information is based upon the historical consolidated financial statements of the Company and should be read in conjunction with the consolidated financial statements and notes thereto. This pro forma information does not purport to represent what the actual results of operations of the Company would have been had the above occurred, nor do they purport to predict the results of operations of future periods.



Pro Forma (Unaudited)	Six Months Ended June 30,
(in thousands, except per share data)	2013		2012
Total revenue	$	1,119,893	$	1,065,877
Income from continuing operations	$	147,627	$	508,812
Net income attributable to Boston Properties, Inc.	$	154,077	$	501,060
Basic earnings per share:
Net income per share attributable to Boston Properties, Inc.	$	1.00	$	3.33
Diluted earnings per share:
Net income per share attributable to Boston Properties, Inc.	$	0.99	$	3.32

Developments

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

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

On June 14, 2013, the Company completed and fully placed in-service 17 Cambridge Center, a Class A office project with approximately 195,000 net rentable square feet located in Cambridge, Massachusetts.

Dispositions

On February 20, 2013, the foreclosure sale of the Company's Montvale Center property was ratified by the court. As a result of the ratification, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate resulting in the recognition of a gain on forgiveness of debt totaling approximately $20.2 million. The operating results of the property through the date of ratification have been classified as discontinued operations on a historical basis for all periods presented.

On June 28, 2013, the Company completed the sale of its 303 Almaden Boulevard property located in San Jose, California for a sale price of $40.0 million. Net cash proceeds totaled approximately $39.3 million. 303 Almaden Boulevard is a Class A office property totaling approximately 158,000 net rentable square feet. Because the Company entered into the related purchase and sale agreement on March 28, 2013 and the carrying value of the property exceeded its net sale price, the Company recognized an impairment loss totaling approximately $3.2 million during the three months ended March 31, 2013. As a result, there was no loss on sale of real estate recognized during the three months ended June 30, 2013. The impairment loss and operating results of this property have been classified as discontinued operations on a historical basis for all periods presented. The sale of this asset caused the Company to reevaluate its strategy for development of its adjacent Almaden land parcel, which can accommodate an approximately 840,000 square feet office complex. Based on a shorter than expected hold period, the Company reduced the carrying value of the land parcel to its estimated fair market value and recognized an impairment loss of approximately $8.3 million during the three months ended March 31, 2013. The Company's estimated fair value, as measured on a non-recurring basis, was based on comparable land sales. The Company has determined that its valuation of the land falls within Level 3 of the fair value hierarchy, as it has utilized significant unobservable inputs in its assessment.

The following table summarizes the income from discontinued operations related to Montvale Center and 303 Almaden Boulevard and the related gain on forgiveness of debt and impairment loss for the three and six months ended June 30, 2013 and 2012 and the gain on sale of real estate and income from discontinued operations for the three and six months ended June 30, 2012 related to the Company's Bedford Business Park properties which were sold on May 17, 2012:



	For the three months ended June 30,						For the six months ended June 30,
	2013			2012			2013			2012
	(in thousands)
Total revenue	$	1,529		$	3,263		$	3,376		$	7,784
Expenses
Operating	656			1,489			1,486			3,392
Depreciation and amortization	—			907			596			2,310
Total expenses	656			2,396			2,082			5,702
Operating income	873			867			1,294			2,082
Other expense
Interest expense	—			(649		)	(360		)	(1,294		)
Income from discontinued operations	$	873		$	218		$	934		$	788
Noncontrolling interest in income from discontinued operations – common units of the Operating Partnership	(88		)	(23		)	(94		)	(84		)
Income from discontinued operations attributable to Boston Properties, Inc.	$	785		$	195		$	840		$	704

Gain on sale of real estate from discontinued operations	$	—		$	36,877		$	—		$	36,877
Gain on forgiveness of debt from discontinued operations	—			—			20,182			—
Impairment loss from discontinued operations	—			—			(3,241		)	—
Noncontrolling interest in gain on sale of real estate, gain on forgiveness of debt and impairment loss from discontinued operations – common units of the Operating Partnership	—			(4,052		)	(1,806		)	(4,075		)
Gain sale of real estate, gain on forgiveness of debt and impairment loss from discontinued operations attributable to Boston Properties, Inc.	$	—		$	32,825		$	15,135		$	32,802

Investments in Unconsolidated Joint Ventures

6 Months Ended

Jun. 30, 2013

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures

Investments in Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at June 30, 2013:



Entity	Properties	Nominal % Ownership
Square 407 Limited Partnership	Market Square North	50.0	%
The Metropolitan Square Associates LLC	Metropolitan Square	51.0	%
BP/CRF 901 New York Avenue LLC	901 New York Avenue	25.0	%	(1)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.3	%	(2)
RBP Joint Venture LLC	Eighth Avenue and 46th Street	50.0	%	(3)
Boston Properties Office Value-Added Fund, L.P.	N/A	39.5	%	(4)
Annapolis Junction NFM, LLC	Annapolis Junction	50.0	%	(5)
2 GCT Venture LLC	N/A	60.0	%	(6)
540 Madison Venture LLC	540 Madison Avenue	60.0	%
125 West 55^th Street Venture LLC	N/A	60.0	%	(7)
500 North Capitol LLC	500 North Capitol Street, NW	30.0	%

_______________


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


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


(3)	See Note 14.


(4)	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of June 30, 2013, the investment is comprised of undistributed cash.


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


(6)	Two Grand Central Tower was sold on October 25, 2011. As of June 30, 2013, the investment is comprised of undistributed cash.


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

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

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



	June 30, 2013			December 31, 2012
	(in thousands)
ASSETS
Real estate and development in process, net	$	949,193		$	4,494,971
Other assets	162,065			673,716
Total assets	$	1,111,258		$	5,168,687
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable	$	745,550		$	3,039,922
Other liabilities	25,756			792,888
Members’/Partners’ equity	339,952			1,335,877
Total liabilities and members’/partners’ equity	$	1,111,258		$	5,168,687
Company’s share of equity	$	167,225		$	787,941
Basis differentials (1)	(29,250		)	(128,025		)
Carrying value of the Company’s investments in unconsolidated joint ventures	$	137,975		$	659,916

_______________

(1)

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

The combined summarized statements of operations of the Company's unconsolidated joint ventures are as follows:



	For the three months ended June 30,						For the six months ended June 30,
	2013			2012			2013			2012
	(in thousands)
Total revenue (1)	$	99,831		$	156,035		$	235,481		$	295,135
Expenses
Operating	32,497			39,261			74,863			78,153
Depreciation and amortization	27,141			42,679			66,418			84,578
Total expenses	59,638			81,940			141,281			162,731
Operating income	40,193			74,095			94,200			132,404
Other income (expense)
Interest expense	(40,054		)	(55,909		)	(96,288		)	(111,271		)
Losses from early extinguishments of debt	(1,677		)	—			(1,677		)	—
Income (loss) from continuing operations	(1,538		)	18,186			(3,765		)	21,133
Gain on sale of real estate	1,766			—			1,766			—
Net income (loss)	$	228		$	18,186		$	(1,999	)	$	21,133

Company’s share of net income (loss)	$	683		$	10,641		$	(1,175	)	$	12,012
Gain on sale of real estate	43,327			—			43,327			—
Basis differential	(2,070		)	431			(1,626		)	897
Elimination of inter-entity interest on partner loan	6,843			10,119			16,978			20,003
Income from unconsolidated joint ventures	$	48,783		$	21,191		$	57,504		$	32,912

Gains on consolidation of joint ventures	$	387,801		$	—		$	387,801		$	—

_______________

(1)

Includes straight-line rent adjustments of $3.1 million and $2.8 million for the three months ended June 30, 2013 and 2012, respectively, and $7.1 million and $7.1 million for the six months ended June 30, 2013 and 2012, respectively. Includes net below-market rent adjustments of $13.5 million and $23.2 million for the three months ended June 30, 2013 and 2012, respectively, and $34.0 million and $48.5 million for the six months ended June 30, 2013 and 2012, respectively. Total revenue for the three and six months ended June 30, 2012 includes termination income totaling approximately $19.6 million (of which the Company's share is approximately $11.8 million) related to a lease termination with a tenant at 767 Fifth Avenue (the General Motors Building).

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

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

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

On April 10, 2013, the Company acquired the Mountain View Research Park and Mountain View Technology Park properties from its Value-Added Fund for an aggregate purchase price of approximately $233.5 million. In conjunction with the acquisition, the Value-Added Fund repaid the mortgage loans collateralized by the Mountain View Research Park and Mountain View Technology Park properties totaling approximately $90.0 million and $20.0 million, respectively, as well as the outstanding loans payable to the Company's Operating Partnership totaling approximately $8.6 million and $3.7 million, respectively. The Mountain View Research Park and Mountain View Technology Park mortgage loans bore interest at variable rates equal to LIBOR plus 2.00% per annum and LIBOR plus 2.50% per annum, respectively and were scheduled to mature on May 31, 2014 and November 22, 2014, respectively. The joint venture recognized a loss on early extinguishment of debt totaling approximately $0.4 million, of which the Company's share was approximately $0.2 million, consisting of the write-off of unamortized deferred financing costs. Prior to the acquisition, the Company's ownership interest in the properties was approximately 39.5%. As a result of the acquisition, the Company owns 100% of the properties and is accounting for them on a consolidated basis (See Note 3). The Company had previously recognized an impairment loss on its investment in the unconsolidated joint venture. As a result, the Company recognized a gain on its investment of approximately $24.4 million, which is included within gains on consolidation of joint ventures in the Company's consolidated statements of operations.

On May 30, 2013, a joint venture in which the Company has a 60% interest completed the sale of its 125 West 55th Street property located in New York City for a sale price of $470.0 million, including the assumption by the buyer of the mortgage loan collateralized by the property totaling approximately $198.6 million. The mortgage loan bore interest at a fixed rate of 6.09% per annum and was scheduled to mature on March 10, 2020. Net cash proceeds totaled approximately $253.7 million, of which the Company's share was approximately $152.2 million, after the payment of transaction costs. 125 West 55th Street is a Class A office property totaling approximately 588,000 net rentable square feet. The Company had previously recognized an impairment loss on its investment in the unconsolidated joint venture. As a result, the Company recognized a gain on sale of real estate totaling approximately $43.3 million, which is included within income from unconsolidated joint ventures in the Company's consolidated statements of operations.

On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that the Company now accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting (See Note 3). Upon consolidation, the Company recognized a non-cash gain on its investment of approximately $363.4 million which is included within gains on consolidation of joint ventures in the Company's consolidated statements of operations.

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

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

Mortgage Notes Payable	6 Months Ended
Mortgage Notes Payable	Jun. 30, 2013
Loans Payable [Abstract]
Mortgage Notes Payable	Mortgage Notes Payable On February 5, 2013, the Company used available cash to repay the mortgage loan collateralized by its Kingstowne One property located in Alexandria, Virginia totaling approximately $17.0 million. The mortgage loan bore interest at a fixed rate of 5.96% per annum and was scheduled to mature on May 5, 2013. There was no prepayment penalty. On February 20, 2013, the foreclosure sale of the Company's Montvale Center property was ratified by the court. As a result of the ratification, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate resulting in the recognition of a gain on forgiveness of debt totaling approximately $20.2 million. The operating results of the property through the date of ratification have been classified as discontinued operations on a historical basis for all periods (See Notes 2 and 3). On April 1, 2013, the Company used available cash to repay the mortgage loan collateralized by its 140 Kendrick Street property located in Needham, Massachusetts totaling approximately $47.6 million. The mortgage loan bore interest at a fixed rate of 7.51% per annum and was scheduled to mature on July 1, 2013. There was no prepayment penalty. The Company recognized a gain on early extinguishment of debt totaling approximately $0.3 million related to the acceleration of the remaining balance of the historical fair value debt adjustment, which was the result of purchase accounting. On May 31, 2013, in conjunction with the consolidation of the Company's 767 Venture, LLC joint venture (the entity that owns 767 Fifth Avenue (the General Motors Building), the Company recorded mortgage loans collateralized by the property aggregating $1.3 billion and mezzanine loans aggregating $306.0 million. The mortgage loans require interest-only payments at a weighted-average fixed interest rate of 5.95% per annum and mature on October 7, 2017. The mezzanine loans require interest-only payments at a weighted-average fixed interest rate of 6.02% per annum and mature on October 7, 2017. The mortgage loans and mezzanine loans were recorded at their fair values aggregating approximately $1.5 billion and $311.7 million, respectively, using weighted-average effective interest rates of approximately 2.44% and 5.53% per annum, respectively. In addition, in conjunction with the consolidation, the Company recorded loans payable to the joint venture's partners totaling $450.0 million and related accrued interest payable totaling approximately $175.8 million. The partner loans bear interest at a fixed rate of 11.0% per annum and mature on June 9, 2017. The Company has eliminated in consolidation its partner loan totaling $270.0 million and its share of the related accrued interest payable. The remaining notes payable to the outside joint venture partners totaling $180.0 million have been reflected as Related Party Notes Payable on the Consolidated Balance Sheets (See Note 3).

Unsecured Senior Notes Unsecured Senior Notes

6 Months Ended

Jun. 30, 2013

Unsecured Senior Notes [Abstract]

Unsecured Senior Notes

6. Unsecured Senior Notes

The following summarizes the unsecured senior notes outstanding as of June 30, 2013 (dollars in thousands):



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

Total principal					5,850,000
Net unamortized discount					(15,027		)
Total					$	5,834,973

_______________


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


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

The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60%, (2) a secured debt leverage ratio not to exceed 50%, (3) an interest coverage ratio of greater than 1.50, and (4) an unencumbered asset value of not less than 150% of unsecured debt. At June 30, 2013, the Company was in compliance with each of these financial restrictions and requirements.

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

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

Unsecured Exchangeable Senior Notes Unsecured Exchangeable Senior Notes

6 Months Ended

Jun. 30, 2013

Unsecured Exchangeable Senior Notes [Abstract]

Unsecured Exchangeable Senior Notes

7. Unsecured Exchangeable Senior Notes

The following summarizes the unsecured exchangeable senior notes outstanding as of June 30, 2013 (dollars in thousands):



	Coupon/ Stated Rate		Effective Rate(1)		Exchange Rate		Principal Amount			First Optional Redemption Date by the Company	Maturity Date
3.625% Exchangeable Senior Notes	3.625	%	4.037	%	8.5051	(2)	$	747,500		N/A	February 15, 2014
Net unamortized discount							(924		)
Adjustment for the equity component allocation, net of accumulated amortization							(12,298		)
Total							$	734,278

_______________


(1)	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs 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 June 30, 2013, the effective exchange price was $134.38 per share.

On April 15, 2013, the Company announced that holders of its Operating Partnership's 3.75% Exchangeable Senior Notes due 2036 (the “Notes”) had the right to surrender their Notes for purchase by the Operating Partnership (the “Put Right”) on May 18, 2013. On April 15, 2013, the Company also announced that the Operating Partnership issued a notice of redemption to the holders of the Notes to redeem, on May 18, 2013 (the “Redemption Date”), all of the Notes outstanding on the Redemption Date. In connection with the notice of redemption, holders of the Notes had the right to exchange their Notes on or prior to May 16, 2013. Notes with respect to which the Put Right was not exercised and that were not surrendered for exchange on or prior to May 16, 2013, were redeemed by the Operating Partnership at a redemption price equal to 100% of the principal amount of the Notes plus accrued and unpaid interest thereon to, but excluding, the Redemption Date. Based on final information provided to the Operating Partnership by the trustee for the Notes, no Notes were validly tendered and accepted for purchase in the Put Right. Pursuant to the notice of redemption, an aggregate principal amount of $990,000 of the Notes was redeemed on May 18, 2013. The remaining aggregate principal amount of $449,010,000 of the Notes was surrendered for exchange and, in addition to the repayment of the principal in cash, the Company issued an aggregate of 419,116 shares of its common stock in exchange for the Notes (See Note 10). The Company recognized a loss on early extinguishment of debt totaling approximately $0.1 million consisting of transaction costs.

Commitments And Contingencies	6 Months Ended
Commitments And Contingencies	Jun. 30, 2013
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	Commitments and Contingencies General In the normal course of business, the Company guarantees its performance of services or indemnifies third parties against its negligence. In addition, in the normal course of business, the Company guarantees to certain tenants the obligations of its subsidiaries for the payment of tenant improvement allowances and brokerage commissions in connection with their leases and limited costs arising from delays in delivery of their premises. The Company has letter of credit and performance obligations of approximately $13.9 million related to lender and development requirements. Certain of the Company’s joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of 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 767 Fifth Avenue's (the General Motors Building) secured loan by the Company’s consolidated joint venture, 767 Venture, LLC, the Company guaranteed the consolidated joint venture’s obligation to fund various escrows, including tenant improvements, taxes and insurance in lieu of cash deposits. As of June 30, 2013, the maximum funding obligation under the guarantee was approximately $28.2 million. The Company earns a fee from the joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee. In connection with the mortgage financing collateralized by the Company's John Hancock Tower property located in Boston, Massachusetts, the Company has agreed to guarantee approximately $4.2 million related to its obligations to provide funds for certain tenant re-leasing costs. The mortgage financing matures on January 6, 2017. From time to time, the Company (or the applicable joint venture) has also agreed to guarantee portions of the principal, interest or other amounts in connection with other unconsolidated joint venture borrowings. In addition to the financial guarantees referenced above, the Company has agreed to customary environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, misrepresentation and bankruptcy) on certain of its unconsolidated joint venture loans. Insurance The Company carries insurance coverage on its properties of types and in amounts and with deductibles that it believes are in line with coverage customarily obtained by owners of similar properties. In response to the uncertainty in the insurance market following the terrorist attacks of September 11, 2001, the Federal Terrorism Risk Insurance Act (as amended, “TRIA”) was enacted in November 2002 to require regulated insurers to make available coverage for “certified” acts of terrorism (as defined by the statute). The expiration date of TRIA was extended to December 31, 2014 by the Terrorism Risk Insurance Program Reauthorization Act of 2007 (“TRIPRA”) and the Company can provide no assurance that it will be extended further. Currently, the Company’s property insurance program per occurrence limits are $1.0 billion for its portfolio insurance program, including coverage for acts of terrorism certified under TRIA other than nuclear, biological, chemical or radiological terrorism (“Terrorism Coverage”). The Company also carries $250 million of Terrorism Coverage for 601 Lexington Avenue, New York, New York (“601 Lexington Avenue”) in excess of the $1.0 billion of coverage in the Company’s property insurance program which is provided by IXP, LLC (“IXP”) as a direct insurer. Certain properties, including the General Motors Building located at 767 Fifth Avenue in New York, New York (“767 Fifth Avenue”), are currently insured in separate insurance programs. The property insurance program per occurrence limits for 767 Fifth Avenue are $1.625 billion, including Terrorism Coverage, with $1.375 billion of Terrorism Coverage in excess of $250 million being provided by NYXP, LLC (“NYXP”), as a direct insurer. The Company also currently carries nuclear, biological, chemical and radiological terrorism insurance coverage for acts of terrorism certified under TRIA (“NBCR Coverage”), which is provided by IXP as a direct insurer, for the properties in our portfolio, including 767 Fifth Avenue, but excluding 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 $100.0 million and the coinsurance is 15%. Under TRIPRA, if the Federal Government pays out for a loss under TRIA, it is mandatory that the Federal Government recoup the full amount of the loss from insurers offering TRIA coverage after the payment of the loss pursuant to a formula in TRIPRA. The Company may elect to terminate the NBCR Coverage if the Federal Government seeks recoupment for losses paid under TRIA, if there is a change in its portfolio or for any other reason. In the event TRIPRA is not extended beyond December 31, 2014, (i) the Company may pursue alternative approaches to secure coverage for acts of terrorism thereby potentially increasing its overall cost of insurance, (ii) if such insurance is not available at commercially reasonable rates with limits equal to its current coverage or at all, the Company may not continue to have full occurrence limit coverage for acts of terrorism, (iii) the Company may not satisfy the insurance requirements under existing or future debt financings secured by individual properties and (iv) we may not be able to obtain future debt financings secured by individual properties. The Company intends to continue to monitor the scope, nature and cost of available terrorism insurance and maintain terrorism insurance in amounts and on terms that are commercially reasonable. The Company also currently carries earthquake insurance on its properties located in areas known to be subject to earthquakes in an amount and subject to self-insurance that the Company believes are commercially reasonable. In addition, this insurance is subject to a deductible in the amount of 5% of the value of the affected property. Specifically, the Company currently carries earthquake insurance which covers its San Francisco region (excluding 680 Folsom Street and 535 Mission Street) with a $120 million per occurrence limit and a $120 million annual aggregate limit, $20 million of which is provided by IXP, as a direct insurer. The builders risk policy maintained for the development of 680 Folsom Street in San Francisco includes a $20 million per occurrence and annual aggregate limit of earthquake coverage. In addition, the builders risk policy maintained for the development of 535 Mission Street in San Francisco includes a $15 million per occurrence and annual aggregate limit of earthquake coverage. 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 Operating Partnership has issued a guarantee to cover liabilities of IXP in the amount of $20.0 million. The mortgages on the Company's properties typically contain requirements concerning the financial ratings of the insurers who provide policies covering the property. The Company provides the lenders on a regular basis with the identity of the insurance companies in the Company's insurance programs. The ratings of some of the Company's insurers are below the rating requirements in some of the Company's loan agreements and the lenders for these loans could attempt to claim that an event of default has occurred under the loan. The Company believes it could obtain insurance with insurers which satisfy the rating requirements. Additionally, in the future, the Company's ability to obtain debt financing secured by individual properties, or the terms of such financing, may be adversely affected if lenders generally insist on ratings for insurers or amounts of insurance which are difficult to obtain or which result in a commercially unreasonable premium. There can be no assurance that a deficiency in the financial ratings of one or more of the Company's insurers will not have a material adverse effect on the Company. The Company continues to monitor the state of the insurance market in general, and the scope and costs of coverage for acts of terrorism and California earthquake risk in particular, but the Company cannot anticipate what coverage will be available on commercially reasonable terms in future policy years. There are other types of losses, such as from wars, for which the Company cannot obtain insurance at all or at a reasonable cost. With respect to such losses and losses from acts of terrorism, earthquakes or other catastrophic events, if the Company experiences a loss that is uninsured or that exceeds policy limits, the Company could lose the capital invested in the damaged properties, as well as the anticipated future revenues from those properties. Depending on the specific circumstances of each affected property, it is possible that the Company could be liable for mortgage indebtedness or other obligations related to the property. Any such loss could materially and adversely affect the Company's business and financial condition and results of operations.

Noncontrolling Interests

6 Months Ended

Jun. 30, 2013

Noncontrolling Interest [Abstract]

Noncontrolling Interests

Noncontrolling interests relate to the interests in the Operating Partnership not owned by the Company and interests in consolidated property partnerships not wholly-owned by the Company. As of June 30, 2013, the noncontrolling interests in the Operating Partnership consisted of 15,739,523 OP Units, 1,464,250 LTIP Units, 397,750 2011 OPP Units, 397,750 2012 OPP Units, 317,406 2013 MYLTIP Units, 995,997 Series Two Preferred Units (or 1,307,083 OP Units on an as converted basis) and 1,221,527 Series Four Preferred Units (not convertible into OP Units) held by parties other than the Company.

Noncontrolling Interest—Redeemable Preferred Units of the Operating Partnership

The Preferred Units at June 30, 2013 included 995,997 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 Operating Partnership to redeem all of the outstanding units for cash at the redemption price of $50.00 per unit on May 12, 2014. The holders also had the right to have 1,007,662 Series Two Preferred Units (or such lesser amount that may have been outstanding) redeemed for cash on each of May 12, 2009, May 12, 2010, May 12, 2011, May 14, 2012 and May 14, 2013, although no holder exercised such right. In May 2014, the Company also has the right, subject to certain conditions, to call for redemption all of the outstanding Series Two Preferred Units for cash or to convert into OP Units any Series Two Preferred Units that have not been previously redeemed. In the event the Company calls the Series Two Preferred Units for redemption, the holders shall have the right to convert the Series Two Preferred Units into OP Units.

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

The Preferred Units at June 30, 2013 also included 1,221,527 Series Four Preferred Units, which bear a preferred distribution equal to 2.00% per annum on a liquidation preference of $50.00 per unit and are not convertible into OP Units. In order to secure the performance of certain obligations by the holders, an aggregate of 360,126 of such Series Four Preferred Units are subject to forfeiture pursuant to the terms of a pledge agreement. The holders of Series Four Preferred Units have the right, at certain times and subject to certain conditions set forth in the Certificate of Designations establishing the rights, limitations and preferences of the Series Four Preferred Units, to require the Operating Partnership to redeem all of their their units for cash at the redemption price of $50.00 per unit. The Operating Partnership also has the right, at certain times and subject to certain conditions, to redeem all of the Series Four Preferred Units for cash at the redemption price of $50.00 per unit. The Series Four Preferred Units that are subject to the security interest under the pledge agreement may not be redeemed until and unless such security interest is released. The Operating Partnership's first right to redeem the Series Four Preferred Units is a 30-day period beginning on August 29, 2013 (See Note 14). Due to the holders' redemption option existing outside the control of the Company, the Series Four Preferred Units are presented outside of permanent equity in the Company's Consolidated Balance Sheets.

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

The following table reflects the activity of the noncontrolling interests—redeemable preferred units of the Operating Partnership for the six months ended June 30, 2013 and 2012 (in thousands):




Balance at January 1, 2013	$	110,876
Net income	2,303
Distributions	(2,303		)
Balance at June 30, 2013	$	110,876

Balance at January 1, 2012	$	55,652
Net income	1,566
Distributions	(1,566		)
Conversion of redeemable preferred units (Series Two Preferred Units) to common units	(4,115		)
Balance at June 30, 2012	$	51,537

Noncontrolling Interest—Redeemable Interest in Property Partnership

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

The following table reflects the activity of the noncontrolling interest—redeemable interest in property partnership in the Company's Fountain Square consolidated joint venture for the six months ended June 30, 2013 (in thousands):



Balance at January 1, 2013	$	97,558
Net loss	(980		)
Distributions	(2,950		)
Adjustment to reflect redeemable interest at redemption value	4,534
Balance at June 30, 2013	$	98,162

Noncontrolling Interest—Common Units of the Operating Partnership

During the six months ended June 30, 2013, 333,997 OP Units were presented by the holders for redemption (including 17,651 OP Units issued upon conversion of LTIP Units) and were redeemed by the Company in exchange for an equal number of shares of Common Stock.

At June 30, 2013, the Company had outstanding 397,750 2011 OPP Units, 397,750 2012 OPP Units and 317,406 2013 MYLTIP Units. Prior to the measurement date (January 31, 2014 for 2011 OPP Units, February 6, 2015 for 2012 OPP Units and February 4, 2016 for 2013 MYLTIP Units), holders of OPP Units and 2013 MYLTIP 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 and 2013 MYLTIP Units, both vested and unvested, that OPP and 2013 MYLTIP award recipients have earned, if any, based on the establishment of a performance pool, will be entitled to receive distributions in an amount per unit equal to distributions, both regular and special, payable on an OP Unit.

On January 29, 2013, the Operating Partnership paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a distribution on the 2011 OPP Units and 2012 OPP Units in the amount of $0.065 per unit, to holders of record as of the close of business on December 31, 2012. On April 30, 2013, the Operating Partnership paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on March 29, 2013. On June 18, 2013, Boston Properties, Inc., as general partner of the Operating Partnership, declared a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit and a distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, in each case payable on July 31, 2013 to holders of record as of the close of business on June 28, 2013.

The Series Two Preferred Units may be converted into OP Units at the election of the holder thereof at any time. A holder of an OP Unit may present such OP Unit to the Operating Partnership 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 Operating Partnership must redeem such OP Unit for cash equal to the then value of a share of common stock of the Company. The Company may, in its sole discretion, elect to assume and satisfy the redemption obligation by paying either cash or issuing one share of Common Stock. The value of the OP Units (not owned by the Company and including LTIP Units assuming that all conditions had been met for the conversion thereof) and Series Two Preferred Units (on an as converted basis) had all of such units been redeemed at June 30, 2013 was approximately $1.8 billion and $137.9 million, respectively, based on the closing price of the Company’s common stock of $105.47 per share on June 30, 2013.

Noncontrolling Interests—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 $489.4 million at June 30, 2013 and approximately $(2.0) million at December 31, 2012, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.

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

On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue(the General Motors Building) in New York City) transferred all of their interests in the joint venture to third parties. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that the Company now accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting. Upon consolidation, the Company recognized the new joint venture partners' aggregate 40% equity interest at its aggregate fair value of approximately $483.5 million within Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets (See Notes 3 and 4).

Stockholders' Equity	6 Months Ended
Stockholders' Equity	Jun. 30, 2013
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity As of June 30, 2013, the Company had 152,384,740 shares of Common Stock outstanding. As of June 30, 2013, approximately $305.3 million remained available for issuance under the Company's $600 million “at the market” stock offering program. During the six months ended June 30, 2013, the Company issued 333,997 shares of Common Stock in connection with the redemption of an equal number of OP Units. On January 29, 2013, the Company paid a dividend in the amount of $0.65 per share of Common Stock to shareholders of record as of the close of business on December 31, 2012. On April 30, 2013, the Company paid a dividend in the amount of $0.65 per share of Common Stock to shareholders of record as of the close of business on March 29, 2013. On June 18, 2013, the Company's Board of Directors declared a dividend of $0.65 per share of Common Stock payable on July 31, 2013 to shareholders of record as of the close of business on June 28, 2013. On March 27, 2013, the Company completed an underwritten public offering of 80,000 shares (8,000,000 depositary shares each representing 1/100th of a share) of its newly designated 5.25% Series B Cumulative Redeemable Preferred Stock, at a price of $2,500.00 per share ($25.00 per depositary share). The net proceeds from this offering were approximately $193.9 million, after deducting the underwriting discount and transaction expenses. The Company contributed the net proceeds to the Operating Partnership in exchange for 80,000 Series B Preferred Units having terms and preferences generally mirroring those of the Series B Preferred Stock. The Company will pay cumulative cash dividends on the Series B Preferred Stock at a rate of 5.25% per annum of the $2,500.00 liquidation preference per share. The Company may not redeem the Series B Preferred Stock prior to March 27, 2018, except in certain circumstances relating to the preservation of the Company's REIT status. On or after March 27, 2018, the Company, at its option, may redeem the Series B Preferred Stock for a cash redemption price of $2,500.00 per share ($25.00 per depositary share), plus all accrued and unpaid dividends. The Series B Preferred Stock is not redeemable by the holders, has no maturity date and is not convertible into any other security of the Company or its affiliates. On May 15, 2013, the Company paid a dividend on its outstanding Series B Preferred Stock of $17.8646 per share. On June 18, 2013, the Company's Board of Directors declared a dividend of $32.8125 per share of Series B Preferred Stock payable on August 15, 2013 to shareholders of record as of the close of business on August 5, 2013. During the six months ended June 30, 2013, the Company issued 419,116 shares of Common Stock in connection with the exchange by holders of its Operating Partnership's 3.75% Exchangeable Senior Notes due 2036 (See Note 7).

- Definition

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

+ References

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 210
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-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Topic 505
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Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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-Paragraph d
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation S-X (SX)
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Reference 16: http://www.xbrl.org/2003/role/presentationRef
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-Name Staff Accounting Bulletin (SAB)
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Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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Reference 18: http://www.xbrl.org/2003/role/presentationRef
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Reference 19: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

Earnings Per Share

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Earnings Per Share

The following table provides a reconciliation of both the net income attributable to Boston Properties, Inc. and the number of common shares used in the computation of basic earnings per share (“EPS”), which is calculated by dividing net income attributable to Boston Properties, Inc. by the weighted-average number of common shares outstanding during the period. The terms of the Series Two Preferred Units enable the holders to obtain OP Units of the Operating Partnership, as well as Common Stock of the 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 share 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 EPS pursuant to the two-class method. As a result, unvested restricted common stock of the Company, LTIP Units, OPP Units and 2013 MYLTIP Units are considered participating securities and are included in the computation of basic and diluted earnings per share of the Company if the effect of applying the if-converted method is dilutive. Because the OPP Units and 2013 MYLTIP Units require the Company 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 EPS calculation. Other potentially dilutive common shares, including stock options, restricted stock and other securities of the Operating Partnership that are exchangeable for the Company’s Common Stock, and the related impact on earnings, are considered when calculating diluted EPS.



	For the three months ended June 30, 2013
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc.	$	451,632		151,938	$	2.97
Discontinued operations attributable to Boston Properties, Inc.	785			—	0.01
Allocation of undistributed earnings to participating securities	(3,629		)	—	(0.03		)
Net income attributable to Boston Properties, Inc. common shareholders	$	448,788		151,938	$	2.95
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—			552	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	448,788		152,490	$	2.94

	For the three months ended June 30, 2012
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc.	$	85,539		150,312	$	0.57
Discontinued operations attributable to Boston Properties, Inc.	33,020			—	0.22
Net income attributable to Boston Properties, Inc. common shareholders	$	118,559		150,312	$	0.79
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—			382	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	118,559		150,694	$	0.78

	For the six months ended June 30, 2013
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc.	$	484,118		151,793	$	3.19
Discontinued operations attributable to Boston Properties, Inc.	15,975			—	0.10
Allocation of undistributed earnings to participating securities	(3,179		)	—	(0.02		)
Net income attributable to Boston Properties, Inc. common shareholders	$	496,914		151,793	$	3.27



Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—		429	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,914	152,222	$	3.26

	For the six months ended June 30,2012
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc.	$	133,465	149,328	$	0.89
Discontinued operations attributable to Boston Properties, Inc.	33,506		—	0.23
Net income attributable to Boston Properties, Inc. common shareholders	$	166,971	149,328	$	1.12
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—		392	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	166,971	149,720	$	1.12

Stock Option and Incentive Plan	6 Months Ended
Stock Option and Incentive Plan	Jun. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option and Incentive Plan	Stock Option and Incentive Plan On January 28, 2013, the Company's Compensation Committee approved multi-year long-term incentive program (MYLTIP) awards under the Company's 2012 Stock Option and Incentive Plan (the "2012 Plan") to officers and employees of the Company. MYLTIP awards utilize total return to shareholders ("TRS") over a three-year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on the Company's TRS relative to (i) the Cohen & Steers Realty Majors Portfolio Index (50% weight) and (ii) the NAREIT Office Index adjusted to exclude the Company (50% weight). Earned awards will range from zero to a maximum of approximately $30.7 million depending on the Company's TRS relative to the two indices, with four tiers (threshold: approximately $5.1 million; target: approximately $10.2 million; high: approximately $20.5 million; exceptional: approximately $30.7 million) and linear interpolation between tiers. Earned awards measured on the basis of relative TRS performance are subject to an absolute TRS component in the form of relatively simple modifiers that (A) reduce the level of earned awards in the event the Company's annualized TRS is less than 2% and (B) cause some awards to be earned in the event the Company's annualized TRS is more than 10% even though on a relative basis alone the Company's TRS would not result in any earned awards. Earned awards (if any) will vest 25% on February 4, 2016, 25% on February 4, 2017 and 50% on February 4, 2018, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by the Company without cause, termination of employment by the award recipient for good reason, death, disability or retirement. If there is a change of control prior to February 4, 2016, earned awards will be calculated based on TRS performance up to the date of the change of control. MYLTIP awards are in the form of LTIP Units issued on the grant date which (i) are subject to forfeiture to the extent awards are not earned and (ii) prior to the performance measurement date are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units. On March 11, 2013, the Company announced that Owen D. Thomas would succeed Mortimer B. Zuckerman as the Company's Chief Executive Officer, effective April 2, 2013. On April 2, 2013, the Company issued 24,231 LTIP units, 38,926 2013 MYLTIP Units and 50,847 non-qualified stock options under the 2012 Plan to Mr. Thomas, pursuant to his employment agreement. Mr. Zuckerman will continue to serve as Executive Chairman for a transition period and thereafter will continue to serve as the Non-Executive Chairman of the Board. In connection with succession planning, the Company and Mr. Zuckerman entered into a Transition Benefits Agreement to recognize his extraordinary services previously rendered and ensure a well-managed transition. If Mr. Zuckerman remains employed by the Company through July 1, 2014, he will be entitled to receive on January 1, 2015 a lump sum cash payment of $6.7 million and an equity award with a targeted value of approximately $11.1 million. The cash payment and equity award vest one-third on each of March 10, 2013, October 1, 2013 and July 1, 2014, subject to acceleration in certain circumstances. As a result, the Company recognized approximately $2.6 million and $9.2 million of compensation expense during the three and six months ended June 30, 2013, respectively. In addition, the agreement provides that if Mr. Zuckerman terminates his employment with the Company for any reason, voluntarily or involuntarily, he will become fully vested in any outstanding equity awards with time-based vesting. As a result, during the six months ended June 30, 2013, the Company accelerated the remaining approximately $12.9 million of stock-based compensation expense associated with Mr. Zuckerman's unvested long-term equity awards. Under the Financial Accounting Standards Board's Accounting Standards Codification (“ASC”) 718 “Compensation-Stock Compensation” the MYLTIP awards granted to employees in February 2013 and granted to Mr. Thomas in April 2013 have an aggregate value of approximately $9.2 million, which amount will generally be amortized into earnings over the five-year plan period under the graded vesting method. During the six months ended June 30, 2013, the Company issued 36,730 shares of restricted common stock, 252,220 non-qualified stock options, 184,733 LTIP Units and 318,926 2013 MYLTIP Units to employees and non-employee directors under the 2012 Plan, including the amounts issued to Mr. Thomas pursuant to his employment agreement, as discussed above. Employees and directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit, OPP Unit and 2013 MYLTIP Unit. An LTIP Unit is generally the economic equivalent of a share of restricted stock in the Company. The aggregate value of the LTIP Units is included in noncontrolling interests in the Consolidated Balance Sheets. Grants of restricted stock and LTIP Units to employees vest in four equal annual installments. Restricted stock is measured at fair value on the date of grant based on the number of shares granted, as adjusted for forfeitures, and the closing price of the Company’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 six months ended June 30, 2013 were valued at approximately $3.9 million ($105.30 per share weighted-average). The non-qualified stock options granted to employees in February 2013 had a weighted-average fair value on the date of grant of $18.46 per option, which was computed using the Black-Scholes option-pricing model utilizing the following weighted-average assumptions: an expected life of 6.0 years, a risk-free interest rate of 1.11%, an expected price volatility of 26% and an expected dividend yield of 3%. The exercise price of the options is $105.10, which was the closing price of the Company’s common stock on the date of grant. The LTIP Units granted to employees in February 2013 were valued at approximately $14.8 million ($96.33 per unit fair value) using a Monte Carlo simulation method model. The per unit fair value of each LTIP Unit granted was estimated on the date of grant using the following assumptions: an expected life of 5.7 years, a risk-free interest rate of 1.03% and an expected price volatility of 26%. As the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units are subject to both a service condition and a market condition, the Company recognizes the compensation expense related to the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units 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 Dividends in Excess of Earnings in the Consolidated Balance Sheets. Aggregate stock-based compensation expense associated with restricted stock, non-qualified stock options, LTIP Units, 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units was approximately $6.4 million and $6.4 million for the three months ended June 30, 2013 and 2012, respectively, and approximately $31.9 million and $17.4 million for the six months ended June 30, 2013 and 2012, respectively. For the three and six months ended June 30, 2013, stock-based compensation expense includes approximately $1.6 million and $18.6 million, respectively, consisting of the acceleration of the expense of the Company’s Executive Chairman’s stock-based compensation awards and the stock-based compensation awards associated with his transition benefits agreement related to the Company's succession planning. For the six months ended June 30, 2012, stock-based compensation expense includes approximately $2.7 million consisting of the acceleration of vesting of the Company’s Chief Operating Officer’s stock-based compensation awards associated with his resignation. At June 30, 2013, there was $22.9 million of unrecognized compensation expense related to unvested restricted stock and LTIP Units and $14.3 million of unrecognized compensation expense related to unvested 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units that is expected to be recognized over a weighted-average period of approximately 3.0 years.

Segment Information

6 Months Ended

Jun. 30, 2013

Segment Reporting [Abstract]

Segment Information

The Company’s segments are based on the Company’s method of internal reporting which classifies its operations by both geographic area and property type. 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, impairment loss, interest expense, depreciation and amortization expense, gains (losses) from investments in securities, gains from early extinguishments of debt, gains on consolidation of joint ventures, 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.

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

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

For the three months ended June 30, 2013:



	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	164,855		$	143,305		$	14,853		$	53,331		$	99,621		$	475,965
Office/Technical	5,538			—			—			5,327			4,031			14,896
Residential	1,065			—			—			—			4,419			5,484
Hotel	11,118			—			—			—			—			11,118
Total	182,576			143,305			14,853			58,658			108,071			507,463
% of Grand Totals	35.98		%	28.24		%	2.93		%	11.56		%	21.29		%	100.0		%
Rental Expenses:
Class A Office	63,181			48,205			7,667			21,264			32,920			173,237
Office/Technical	1,627			—			—			1,116			1,027			3,770
Residential	407			—			—			—			2,423			2,830
Hotel	7,335			—			—			—			—			7,335
Total	72,550			48,205			7,667			22,380			36,370			187,172
% of Grand Totals	38.76		%	25.75		%	4.10		%	11.96		%	19.43		%	100.0		%
Net operating income	$	110,026		$	95,100		$	7,186		$	36,278		$	71,701		$	320,291
% of Grand Totals	34.35		%	29.69		%	2.24		%	11.33		%	22.39		%	100.0		%

For the three months ended June 30, 2012:



	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	157,642		$	122,657		$	15,617		$	52,102		$	88,740		$	436,758
Office/Technical	5,744			—			—			144			4,054			9,942
Residential	1,013			—			—			—			4,023			5,036
Hotel	10,049			—			—			—			—			10,049
Total	174,448			122,657			15,617			52,246			96,817			461,785
% of Grand Totals	37.78		%	26.56		%	3.38		%	11.31		%	20.97		%	100.0		%
Rental Expenses:
Class A Office	60,504			38,936			7,691			20,507			28,306			155,944
Office/Technical	1,652			—			—			38			964			2,654
Residential	367			—			—			—			2,207			2,574
Hotel	6,616			—			—			—			—			6,616
Total	69,139			38,936			7,691			20,545			31,477			167,788
% of Grand Totals	41.21		%	23.21		%	4.58		%	12.24		%	18.76		%	100.0		%
Net operating income	$	105,309		$	83,721		$	7,926		$	31,701		$	65,340		$	293,997
% of Grand Totals	35.82		%	28.48		%	2.70		%	10.78		%	22.22		%	100.0		%

For the six months ended June 30, 2013:



	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	326,358		$	265,401		$	31,280		$	106,002		$	197,486		$	926,527
Office/Technical	11,191			—			—			5,478			8,074			24,743
Residential	2,132			—			—			—			8,930			11,062
Hotel	19,409			—			—			—			—			19,409
Total	359,090			265,401			31,280			111,480			214,490			981,741
% of Grand Totals	36.58		%	27.03		%	3.19		%	11.35		%	21.85		%	100.0		%
Rental Expenses:
Class A Office	128,913			90,092			15,314			41,136			64,843			340,298
Office/Technical	3,414			—			—			1,151			2,031			6,596
Residential	850			—			—			—			4,713			5,563
Hotel	14,379			—			—			—			—			14,379
Total	147,556			90,092			15,314			42,287			71,587			366,836
% of Grand Totals	40.22		%	24.56		%	4.17		%	11.53		%	19.52		%	100.0		%
Net operating income	$	211,534		$	175,309		$	15,966		$	69,193		$	142,903		$	614,905
% of Grand Totals	34.40		%	28.51		%	2.60		%	11.25		%	23.24		%	100.0		%

For the six months ended June 30, 2012:



	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	298,650		$	240,246		$	30,467		$	102,766		$	179,137		$	851,266
Office/Technical	11,343			—			—			196			8,146			19,685
Residential	1,896			—			—			—			7,621			9,517
Hotel	16,865			—			—			—			—			16,865
Total	328,754			240,246			30,467			102,962			194,904			897,333
% of Grand Totals	36.64		%	26.77		%	3.40		%	11.47		%	21.72		%	100.0		%
Rental Expenses:
Class A Office	118,337			77,443			15,049			39,924			55,747			306,500
Office/Technical	3,152			—			—			62			2,011			5,225
Residential	757			—			—			—			4,532			5,289
Hotel	12,715			—			—			—			—			12,715
Total	134,961			77,443			15,049			39,986			62,290			329,729
% of Grand Totals	40.93		%	23.49		%	4.56		%	12.13		%	18.89		%	100.0		%
Net operating income	$	193,793		$	162,803		$	15,418		$	62,976		$	132,614		$	567,604
% of Grand Totals	34.14		%	28.68		%	2.72		%	11.10		%	23.36		%	100.0		%

The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties, Inc.:



	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012
Net Operating Income	$	320,291		$	293,997		$	614,905		$	567,604
Add:
Development and management services income	7,857			9,564			16,593			17,709
Income from unconsolidated joint ventures	48,783			21,191			57,504			32,912
Gains on consolidation of joint ventures	387,801			—			387,801			—
Interest and other income	1,296			2,382			2,767			4,028
Gains (losses) from investments in securities	181			(186		)	916			615
Gains from early extinguishments of debt	152			274			152			1,041
Income from discontinued operations	873			218			934		—	788
Gain on sale of real estate from discontinued operations	—			36,877			—			36,877
Gain on forgiveness of debt from discontinued operations	—			—			20,182			—
Less:
General and administrative expense	22,194			19,066			65,765			46,685
Transaction costs	535			8			978			2,112
Depreciation and amortization expense	134,604			111,168			255,199			219,630
Interest expense	103,140			99,901			203,573		—	203,138
Impairment loss	—			—			8,306			—
Impairment loss from discontinued operations	—			—			3,241			—
Noncontrolling interest in property partnerships	(219		)	457			2,355		—	1,003
Noncontrolling interest—redeemable preferred units of the Operating Partnership	1,123			765			2,303		—	1,566
Noncontrolling interest—common units of the Operating Partnership	50,734			10,318			55,277		—	16,310
Noncontrolling interest in discontinued operations—common units of the Operating Partnership	88			4,075			1,900		—	4,159
Net income attributable to Boston Properties, Inc.	$	455,035		$	118,559		$	502,857		$	166,971

- Definition

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

+ References

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

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

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

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

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

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

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

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

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

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

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

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

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

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

+ Details

Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2013
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On July 1, 2013, the Company completed and fully placed in-service its Cambridge Center Connector project with approximately 43,000 net rentable square feet located in Cambridge, Massachusetts. On July 15, 2013, the Company executed a binding contract for the sale of its 1301 New York Avenue property located in Washington, DC for a net contract sale price of approximately $121.7 million. After adjusting for outstanding lease and other transaction costs to be assumed by the buyer, the gross sale price is approximately $135.0 million. 1301 New York Avenue is a Class A office property totaling approximately 201,000 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 July 19, 2013, a joint venture in which the Company has a 50% interest completed the sale of its Eighth Avenue and 46th Street project located in New York City for an imputed sale price of $45.0 million. The Eighth Avenue and 46th Street project is comprised of an assemblage of land parcels and air-rights. Net cash proceeds to the Company totaled approximately $21.8 million, after the payment of transaction costs. On July 26, 2013, the Company's Operating Partnership amended and restated the revolving credit agreement governing the Company's Unsecured Line of Credit, which, among other things, (1) increased the total commitment from $750.0 million to $1.0 billion, (2) extended the maturity date from June 24, 2014 to July 26, 2018 and (3) reduced the per annum variable interest rates and other fees. The Operating Partnership may increase the total commitment to $1.5 billion, subject to syndication of the increase and other conditions. At the Operating Partnership’s option, loans outstanding under the Unsecured Line of Credit will bear interest at a rate per annum equal to (1), in the case of loans denominated in Dollars, Euro or Sterling, LIBOR or, in the case of loans denominated in Canadian Dollars, CDOR, in each case, plus a margin ranging from 0.925% to 1.70% based on the Operating Partnership’s credit rating or (2) an alternate base rate equal to the greatest of (a) the Administrative Agent’s prime rate, (b) the Federal Funds rate plus 0.5% or (c) LIBOR for a one month period plus 1.00%, in each case, plus a margin ranging from 0.0% to 0.70% based on the Operating Partnership’s credit rating. The Unsecured Line of Credit also contains a competitive bid option that allows banks that are part of the lender consortium to bid to make loan advances to the Operating Partnership at a reduced interest rate. In addition, the Operating Partnership is also obligated to pay (1) in quarterly installments a facility fee on the total commitment at a rate per annum ranging from 0.125% to 0.35% based on the Operating Partnership’s credit rating and (2) an annual fee on the undrawn amount of each letter of credit equal to the LIBOR margin. Based on the Operating Partnership’s current credit rating, the LIBOR and CDOR margin is 1.00%, the alternate base rate margin is 0.0% and the facility fee is 0.15%. On August 7, 2013, the Company elected to redeem approximately 861,400 Series Four Preferred Units for cash at the redemption price of $50.00 per unit plus accrued and unpaid distributions through the redemption date of August 29, 2013.

Basis Of Presentation And Summary Of Significant Accounting Policies Recent Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 30, 2013
Recent Accounting Pronouncements [Abstract]
Recent Accounting Pronouncement [Policy Text Block]	Recent Accounting Pronouncements In February 2013, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2013-02, "Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income" (“ASU No. 2013-02”). ASU No. 2013-02 requires an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component. In addition, an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income, but only if the amount reclassified is required to be reclassified to net income in its entirety in the same reporting period. For other amounts that are not required to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures that provide additional detail about those amounts. ASU No. 2013-02 is effective prospectively for reporting periods beginning after December 15, 2012. The Company’s adoption of ASU No. 2013-02 did not have a material impact on its consolidated financial statements.

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

6 Months Ended

Jun. 30, 2013

Accounting Policies [Abstract]

Revision of prior period amounts for Montvale Center [Table Text Block]



	For the three months ended June 30, 2012				For the six months ended June 30, 2012
	As Reported		As Revised		As Reported		As Revised
	(in thousands, except for per share amounts)

Total revenue	$	472,897	$	471,349	$	918,124	$	915,042
Income from continuing operations	$	97,471	$	97,079	$	153,188	$	152,344
Discontinued operations	$	37,275	$	37,095	$	55,568	$	37,665
Net income attributable to Boston Properties, Inc. common shareholders	$	119,070	$	118,559	$	183,672	$	166,971
Income attributable to Boston Properties, Inc. common shareholders per share—basic	$	0.79	$	0.79	$	1.23	$	1.12
Income attributable to Boston Properties, Inc. common shareholders per share—diluted	$	0.79	$	0.78	$	1.23	$	1.12

Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value

The following table presents the aggregate carrying value of the Company’s indebtedness and the Company’s corresponding estimate of fair value as of June 30, 2013 and December 31, 2012 (in thousands):



	June 30, 2013					December 31, 2012
	Carrying Amount			Estimated Fair Value		Carrying Amount			Estimated Fair Value
Mortgage notes payable	$	4,484,657		$	4,598,927	$	3,102,485		$	3,256,940
Mezzanine notes payable	311,637			311,665		—			—
Unsecured senior notes	5,834,973			6,093,237		4,639,528			5,162,486
Unsecured exchangeable senior notes	734,278		(1)	772,691		1,170,356		(1)	1,278,554
Total	$	11,365,545		$	11,776,520	$	8,912,369		$	9,697,980

_______________


(1)	Includes the net adjustment for the equity component allocation totaling approximately $12.3 million and $25.5 million at June 30, 2013 and December 31, 2012, respectively.

Real Estate Activity During the Six Months Ended June 30, 2013 (Tables)

6 Months Ended

Jun. 30, 2013

Business Acquisition [Line Items]

Business Acquisition, Pro Forma Information [Table Text Block]



Pro Forma (Unaudited)	Six Months Ended June 30,
(in thousands, except per share data)	2013		2012
Total revenue	$	1,119,893	$	1,065,877
Income from continuing operations	$	147,627	$	508,812
Net income attributable to Boston Properties, Inc.	$	154,077	$	501,060
Basic earnings per share:
Net income per share attributable to Boston Properties, Inc.	$	1.00	$	3.33
Diluted earnings per share:
Net income per share attributable to Boston Properties, Inc.	$	0.99	$	3.32

Summary Of The Discontinued Operations Related To Montvale Center, 303 Almaden Blvd and Bedford Business Park



	For the three months ended June 30,						For the six months ended June 30,
	2013			2012			2013			2012
	(in thousands)
Total revenue	$	1,529		$	3,263		$	3,376		$	7,784
Expenses
Operating	656			1,489			1,486			3,392
Depreciation and amortization	—			907			596			2,310
Total expenses	656			2,396			2,082			5,702
Operating income	873			867			1,294			2,082
Other expense
Interest expense	—			(649		)	(360		)	(1,294		)
Income from discontinued operations	$	873		$	218		$	934		$	788
Noncontrolling interest in income from discontinued operations – common units of the Operating Partnership	(88		)	(23		)	(94		)	(84		)
Income from discontinued operations attributable to Boston Properties, Inc.	$	785		$	195		$	840		$	704

Gain on sale of real estate from discontinued operations	$	—		$	36,877		$	—		$	36,877
Gain on forgiveness of debt from discontinued operations	—			—			20,182			—
Impairment loss from discontinued operations	—			—			(3,241		)	—
Noncontrolling interest in gain on sale of real estate, gain on forgiveness of debt and impairment loss from discontinued operations – common units of the Operating Partnership	—			(4,052		)	(1,806		)	(4,075		)
Gain sale of real estate, gain on forgiveness of debt and impairment loss from discontinued operations attributable to Boston Properties, Inc.	$	—		$	32,825		$	15,135		$	32,802

Mountain View Research And Technology Parks [Member]

Business Acquisition [Line Items]

Schedule of Business Acquisitions, by Acquisition [Table Text Block]

The following table summarizes the allocation of the aggregate purchase price of Mountain View Research Park and Mountain View Technology Park at the date of acquisition (in thousands).



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

767 Fifth Avenue (The GM Building) [Member]

Business Acquisition [Line Items]

Schedule of Business Acquisitions, by Acquisition [Table Text Block]

The following table summarizes the allocation of the aggregate purchase price of 767 Fifth Avenue (the General Motors Building) at the date of consolidation on May 31, 2013 (in thousands).



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

Working capital recorded upon consolidation
Cash and cash equivalents	$	79,468
Cash held in escrows	2,403
Tenant and other receivables	7,104
Prepaid expenses and other assets	4,269
Accounts payable and accrued expenses	(2,418		)
Accrued interest payable	(175,802		)	(2)
Other liabilities	(6,304		)
	$	(91,280	)

Noncontrolling interest recorded upon consolidation
Noncontrolling interests	$	(520,000	)
Noncontrolling interests - working capital	36,512
	$	(483,488	)

Net assets recorded upon consolidation	$	725,232

_______________

(1) The Company's partner loans totaling $270.0 million eliminates in consolidation.

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

- Definition

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

+ References + Details

Investments in Unconsolidated Joint Ventures (Tables)

6 Months Ended

Jun. 30, 2013

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at June 30, 2013:



Entity	Properties	Nominal % Ownership
Square 407 Limited Partnership	Market Square North	50.0	%
The Metropolitan Square Associates LLC	Metropolitan Square	51.0	%
BP/CRF 901 New York Avenue LLC	901 New York Avenue	25.0	%	(1)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.3	%	(2)
RBP Joint Venture LLC	Eighth Avenue and 46th Street	50.0	%	(3)
Boston Properties Office Value-Added Fund, L.P.	N/A	39.5	%	(4)
Annapolis Junction NFM, LLC	Annapolis Junction	50.0	%	(5)
2 GCT Venture LLC	N/A	60.0	%	(6)
540 Madison Venture LLC	540 Madison Avenue	60.0	%
125 West 55^th Street Venture LLC	N/A	60.0	%	(7)
500 North Capitol LLC	500 North Capitol Street, NW	30.0	%

_______________


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


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


(3)	See Note 14.


(4)	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of June 30, 2013, the investment is comprised of undistributed cash.


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


(6)	Two Grand Central Tower was sold on October 25, 2011. As of June 30, 2013, the investment is comprised of undistributed cash.


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

Schedule Of Balance Sheets Of The Unconsolidated Joint Ventures [Text Block]

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



	June 30, 2013			December 31, 2012
	(in thousands)
ASSETS
Real estate and development in process, net	$	949,193		$	4,494,971
Other assets	162,065			673,716
Total assets	$	1,111,258		$	5,168,687
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable	$	745,550		$	3,039,922
Other liabilities	25,756			792,888
Members’/Partners’ equity	339,952			1,335,877
Total liabilities and members’/partners’ equity	$	1,111,258		$	5,168,687
Company’s share of equity	$	167,225		$	787,941
Basis differentials (1)	(29,250		)	(128,025		)
Carrying value of the Company’s investments in unconsolidated joint ventures	$	137,975		$	659,916

_______________

(1)

Statements Of Operations Of The Joint Ventures

The combined summarized statements of operations of the Company's unconsolidated joint ventures are as follows:



	For the three months ended June 30,						For the six months ended June 30,
	2013			2012			2013			2012
	(in thousands)
Total revenue (1)	$	99,831		$	156,035		$	235,481		$	295,135
Expenses
Operating	32,497			39,261			74,863			78,153
Depreciation and amortization	27,141			42,679			66,418			84,578
Total expenses	59,638			81,940			141,281			162,731
Operating income	40,193			74,095			94,200			132,404
Other income (expense)
Interest expense	(40,054		)	(55,909		)	(96,288		)	(111,271		)
Losses from early extinguishments of debt	(1,677		)	—			(1,677		)	—
Income (loss) from continuing operations	(1,538		)	18,186			(3,765		)	21,133
Gain on sale of real estate	1,766			—			1,766			—
Net income (loss)	$	228		$	18,186		$	(1,999	)	$	21,133

Company’s share of net income (loss)	$	683		$	10,641		$	(1,175	)	$	12,012
Gain on sale of real estate	43,327			—			43,327			—
Basis differential	(2,070		)	431			(1,626		)	897
Elimination of inter-entity interest on partner loan	6,843			10,119			16,978			20,003
Income from unconsolidated joint ventures	$	48,783		$	21,191		$	57,504		$	32,912

Gains on consolidation of joint ventures	$	387,801		$	—		$	387,801		$	—

_______________

(1)

Unsecured Senior Notes (Tables)

6 Months Ended

Jun. 30, 2013

Unsecured Senior Notes [Abstract]

Schedule of Unsecured Senior Notes [Table Text Block]

The following summarizes the unsecured senior notes outstanding as of June 30, 2013 (dollars in thousands):



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

Total principal					5,850,000
Net unamortized discount					(15,027		)
Total					$	5,834,973

_______________


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


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

Unsecured Exchangeable Senior Notes (Tables)

6 Months Ended

Jun. 30, 2013

Unsecured Exchangeable Senior Notes [Abstract]

Schedule of Unsecured Exchangeable Senior Notes

The following summarizes the unsecured exchangeable senior notes outstanding as of June 30, 2013 (dollars in thousands):



	Coupon/ Stated Rate		Effective Rate(1)		Exchange Rate		Principal Amount			First Optional Redemption Date by the Company	Maturity Date
3.625% Exchangeable Senior Notes	3.625	%	4.037	%	8.5051	(2)	$	747,500		N/A	February 15, 2014
Net unamortized discount							(924		)
Adjustment for the equity component allocation, net of accumulated amortization							(12,298		)
Total							$	734,278

_______________


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

(2)

Noncontrolling Interests (Tables)

6 Months Ended

Jun. 30, 2013

Noncontrolling Interest [Abstract]

Schedule Of Series Two Preferred Units

The following table reflects the activity of the noncontrolling interests—redeemable preferred units of the Operating Partnership for the six months ended June 30, 2013 and 2012 (in thousands):




Balance at January 1, 2013	$	110,876
Net income	2,303
Distributions	(2,303		)
Balance at June 30, 2013	$	110,876

Balance at January 1, 2012	$	55,652
Net income	1,566
Distributions	(1,566		)
Conversion of redeemable preferred units (Series Two Preferred Units) to common units	(4,115		)
Balance at June 30, 2012	$	51,537

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



Balance at January 1, 2013	$	97,558
Net loss	(980		)
Distributions	(2,950		)
Adjustment to reflect redeemable interest at redemption value	4,534
Balance at June 30, 2013	$	98,162

Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Computation Of Basic And Diluted Earnings Per Share



	For the three months ended June 30, 2013
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc.	$	451,632		151,938	$	2.97
Discontinued operations attributable to Boston Properties, Inc.	785			—	0.01
Allocation of undistributed earnings to participating securities	(3,629		)	—	(0.03		)
Net income attributable to Boston Properties, Inc. common shareholders	$	448,788		151,938	$	2.95
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—			552	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	448,788		152,490	$	2.94

	For the three months ended June 30, 2012
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc.	$	85,539		150,312	$	0.57
Discontinued operations attributable to Boston Properties, Inc.	33,020			—	0.22
Net income attributable to Boston Properties, Inc. common shareholders	$	118,559		150,312	$	0.79
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—			382	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	118,559		150,694	$	0.78

	For the six months ended June 30, 2013
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc.	$	484,118		151,793	$	3.19
Discontinued operations attributable to Boston Properties, Inc.	15,975			—	0.10
Allocation of undistributed earnings to participating securities	(3,179		)	—	(0.02		)
Net income attributable to Boston Properties, Inc. common shareholders	$	496,914		151,793	$	3.27



Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—		429	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,914	152,222	$	3.26

	For the six months ended June 30,2012
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc.	$	133,465	149,328	$	0.89
Discontinued operations attributable to Boston Properties, Inc.	33,506		—	0.23
Net income attributable to Boston Properties, Inc. common shareholders	$	166,971	149,328	$	1.12
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes	—		392	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	166,971	149,720	$	1.12

Segment Information (Tables)

6 Months Ended

Jun. 30, 2013

Segment Reporting [Abstract]

Schedule Of Segment Information By Geographic Area And Property Type

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

For the three months ended June 30, 2013:



	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	164,855		$	143,305		$	14,853		$	53,331		$	99,621		$	475,965
Office/Technical	5,538			—			—			5,327			4,031			14,896
Residential	1,065			—			—			—			4,419			5,484
Hotel	11,118			—			—			—			—			11,118
Total	182,576			143,305			14,853			58,658			108,071			507,463
% of Grand Totals	35.98		%	28.24		%	2.93		%	11.56		%	21.29		%	100.0		%
Rental Expenses:
Class A Office	63,181			48,205			7,667			21,264			32,920			173,237
Office/Technical	1,627			—			—			1,116			1,027			3,770
Residential	407			—			—			—			2,423			2,830
Hotel	7,335			—			—			—			—			7,335
Total	72,550			48,205			7,667			22,380			36,370			187,172
% of Grand Totals	38.76		%	25.75		%	4.10		%	11.96		%	19.43		%	100.0		%
Net operating income	$	110,026		$	95,100		$	7,186		$	36,278		$	71,701		$	320,291
% of Grand Totals	34.35		%	29.69		%	2.24		%	11.33		%	22.39		%	100.0		%

For the three months ended June 30, 2012:



	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	157,642		$	122,657		$	15,617		$	52,102		$	88,740		$	436,758
Office/Technical	5,744			—			—			144			4,054			9,942
Residential	1,013			—			—			—			4,023			5,036
Hotel	10,049			—			—			—			—			10,049
Total	174,448			122,657			15,617			52,246			96,817			461,785
% of Grand Totals	37.78		%	26.56		%	3.38		%	11.31		%	20.97		%	100.0		%
Rental Expenses:
Class A Office	60,504			38,936			7,691			20,507			28,306			155,944
Office/Technical	1,652			—			—			38			964			2,654
Residential	367			—			—			—			2,207			2,574
Hotel	6,616			—			—			—			—			6,616
Total	69,139			38,936			7,691			20,545			31,477			167,788
% of Grand Totals	41.21		%	23.21		%	4.58		%	12.24		%	18.76		%	100.0		%
Net operating income	$	105,309		$	83,721		$	7,926		$	31,701		$	65,340		$	293,997
% of Grand Totals	35.82		%	28.48		%	2.70		%	10.78		%	22.22		%	100.0		%

For the six months ended June 30, 2013:



	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	326,358		$	265,401		$	31,280		$	106,002		$	197,486		$	926,527
Office/Technical	11,191			—			—			5,478			8,074			24,743
Residential	2,132			—			—			—			8,930			11,062
Hotel	19,409			—			—			—			—			19,409
Total	359,090			265,401			31,280			111,480			214,490			981,741
% of Grand Totals	36.58		%	27.03		%	3.19		%	11.35		%	21.85		%	100.0		%
Rental Expenses:
Class A Office	128,913			90,092			15,314			41,136			64,843			340,298
Office/Technical	3,414			—			—			1,151			2,031			6,596
Residential	850			—			—			—			4,713			5,563
Hotel	14,379			—			—			—			—			14,379
Total	147,556			90,092			15,314			42,287			71,587			366,836
% of Grand Totals	40.22		%	24.56		%	4.17		%	11.53		%	19.52		%	100.0		%
Net operating income	$	211,534		$	175,309		$	15,966		$	69,193		$	142,903		$	614,905
% of Grand Totals	34.40		%	28.51		%	2.60		%	11.25		%	23.24		%	100.0		%

For the six months ended June 30, 2012:



	Boston			New York			Princeton			San Francisco			Washington, DC			Total
Rental Revenue:
Class A Office	$	298,650		$	240,246		$	30,467		$	102,766		$	179,137		$	851,266
Office/Technical	11,343			—			—			196			8,146			19,685
Residential	1,896			—			—			—			7,621			9,517
Hotel	16,865			—			—			—			—			16,865
Total	328,754			240,246			30,467			102,962			194,904			897,333
% of Grand Totals	36.64		%	26.77		%	3.40		%	11.47		%	21.72		%	100.0		%
Rental Expenses:
Class A Office	118,337			77,443			15,049			39,924			55,747			306,500
Office/Technical	3,152			—			—			62			2,011			5,225
Residential	757			—			—			—			4,532			5,289
Hotel	12,715			—			—			—			—			12,715
Total	134,961			77,443			15,049			39,986			62,290			329,729
% of Grand Totals	40.93		%	23.49		%	4.56		%	12.13		%	18.89		%	100.0		%
Net operating income	$	193,793		$	162,803		$	15,418		$	62,976		$	132,614		$	567,604
% of Grand Totals	34.14		%	28.68		%	2.72		%	11.10		%	23.36		%	100.0		%

Schedule Of Reconciliation Of Net Operating Income To Net Income

The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties, Inc.:



	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012
Net Operating Income	$	320,291		$	293,997		$	614,905		$	567,604
Add:
Development and management services income	7,857			9,564			16,593			17,709
Income from unconsolidated joint ventures	48,783			21,191			57,504			32,912
Gains on consolidation of joint ventures	387,801			—			387,801			—
Interest and other income	1,296			2,382			2,767			4,028
Gains (losses) from investments in securities	181			(186		)	916			615
Gains from early extinguishments of debt	152			274			152			1,041
Income from discontinued operations	873			218			934		—	788
Gain on sale of real estate from discontinued operations	—			36,877			—			36,877
Gain on forgiveness of debt from discontinued operations	—			—			20,182			—
Less:
General and administrative expense	22,194			19,066			65,765			46,685
Transaction costs	535			8			978			2,112
Depreciation and amortization expense	134,604			111,168			255,199			219,630
Interest expense	103,140			99,901			203,573		—	203,138
Impairment loss	—			—			8,306			—
Impairment loss from discontinued operations	—			—			3,241			—
Noncontrolling interest in property partnerships	(219		)	457			2,355		—	1,003
Noncontrolling interest—redeemable preferred units of the Operating Partnership	1,123			765			2,303		—	1,566
Noncontrolling interest—common units of the Operating Partnership	50,734			10,318			55,277		—	16,310
Noncontrolling interest in discontinued operations—common units of the Operating Partnership	88			4,075			1,900		—	4,159
Net income attributable to Boston Properties, Inc.	$	455,035		$	118,559		$	502,857		$	166,971

Organization (Details) ft² in Millions	3 Months Ended	6 Months Ended		60 Months Ended
Organization (Details) ft² in Millions	Jun. 30, 2013 a ft² Real_Estate_Properties Vehicles shares $ / shares	Jun. 30, 2013 a ft² Real_Estate_Properties Vehicles shares $ / shares yr	Jun. 30, 2012	Mar. 26, 2018	Aug. 07, 2013 $ / shares	Dec. 31, 2012 shares
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)		89.20%	88.50%
Restriction on redemption of OP units from date of issuance (years) \| yr		1
One OP unit is equivalent to one share of Common Stock (in shares) \| shares	1	1
OP unit conversion rate (in shares) \| shares	1	1
Number Of Series Of Preferred Units Outstanding \| shares	3	3
Number of vehicles in structured parking \| Vehicles	46,411	46,411
Area of parking (in square feet) \| ft²	15.7	15.7
Area of undeveloped land parcels owned (in acres) \| a	512.8	512.8
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	179	179
Net Rentable Area \| ft²	44.8	44.8
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	8	8
Net Rentable Area \| ft²	2.8	2.8
Total Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	171	171
Class A Office Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	131	131
Office Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	7	7
Office Technical Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	40	40
Hotel Property [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	1	1
Retail Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	4	4
Residential Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	3	3
Residential Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties	1	1
Series B Cumulative Redeemable Preferred Stock [Member]
Real Estate Properties [Line Items]
Series B, Shares Outstanding \| shares	80,000	80,000				0
Series B, Dividend Rate, Percentage				5.25%
Depository shares of Series B Cumulative Redeemable Preferred [Member]
Real Estate Properties [Line Items]
Series B, Shares Outstanding \| shares	8,000,000	8,000,000
Series Two Preferred Units [Member]
Real Estate Properties [Line Items]
OP Units for each Preferred Unit (in shares) \| shares	1.312336
Preferred Units Liquidation Preference \| $ / shares	$ 50.00	$ 50.00
series four preferred units [Member]
Real Estate Properties [Line Items]
Preferred Units Liquidation Preference \| $ / shares	50.00	$ 50.00			$ 50.00
Quarterly Distributions to Series Four Preferred Units \| $ / shares	$ 0.25
Series Four Preferred Units Annual Dividend Payable Rate	2.00%
Series B Preferred Units [Member]
Real Estate Properties [Line Items]
Series B, Shares Outstanding \| shares	80,000	80,000

Basis Of Presentation And Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2012 USD ($)
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

Jun. 30, 2013

Dec. 31, 2012

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable

$ 4,484,657

$ 3,102,485

Mezzanine notes payable

311,637

Unsecured senior notes

5,834,973

4,639,528

Unsecured exchangeable senior notes

734,278

1,170,356

Impact of accounting pronouncement

(12,298)

Carrying Amount [Member]

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable

4,484,657

3,102,485

Mezzanine notes payable

311,637

Unsecured senior notes

5,834,973

4,639,528

Unsecured exchangeable senior notes

^[1]

734,278

1,170,356

Total

11,365,545

8,912,369

Estimated Fair Value [Member]

Summary Of Significant Accounting Policies [Line Items]

Mortgage notes payable

4,598,927

3,256,940

Mezzanine notes payable

311,665

Unsecured senior notes

6,093,237

5,162,486

Unsecured exchangeable senior notes

772,691

1,278,554

Total

11,776,520

9,697,980

ASC 470-20 Adjustment [Member]

Summary Of Significant Accounting Policies [Line Items]

Impact of accounting pronouncement

$ 12,300

$ 25,500

[1]	Includes the net adjustment for the equity component allocation totaling approximately $12.3 million and $25.5 million at June 30, 2013 and December 31, 2012, respectively.

Basis Of Presentation And Summary Of Significant Accounting Policies Revision of Prior Period Amounts for Montvale Center (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Feb. 20, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue		$ 515,320	$ 471,349	$ 998,334	$ 915,042
Income from continuing operations		505,888	97,079	546,817	152,344
Discontinued Operations		873	218	934	788
Net income attributable to Boston Properties, Inc. common shareholders		$ 452,417	$ 118,559	$ 500,093	$ 166,971
Income attributable to Boston Properties, Inc. common shareholders per share -basic		$ 2.95	$ 0.79	$ 3.27	$ 1.12
Inceom (loss) from continuing operations before discontinued operations and allocation of undistributed earnings (dollars per share)		2.97		3.19
Income attributable to Boston Properties, Inc. common shareholders per share -diluted		$ 2.94	$ 0.78	$ 3.26	$ 1.12
Gain on forgiveness of debt from discontinued operations		$ 0	$ 0	$ 20,182	$ 0
Montvale Center [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Amount of debt extinguished					25,000
Gain on forgiveness of debt from discontinued operations	$ 20,200				17,800
As Revised [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue			471,349		915,042
Income from continuing operations			97,079		152,344
Discontinued Operations			37,095		37,665
Net income attributable to Boston Properties, Inc. common shareholders			$ 118,559		$ 166,971
Income attributable to Boston Properties, Inc. common shareholders per share -basic			$ 0.79		$ 1.12
Income attributable to Boston Properties, Inc. common shareholders per share -diluted			$ 0.78		$ 1.12
As Reported [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue			$ 472,897		$ 918,124
Income from continuing operations			97,471		153,188
Discontinued Operations			37,275		55,568
Net income attributable to Boston Properties, Inc. common shareholders			$ 119,070		$ 183,672
Income attributable to Boston Properties, Inc. common shareholders per share -basic			$ 0.79		$ 1.23
Income attributable to Boston Properties, Inc. common shareholders per share -diluted			$ 0.79		$ 1.23

Real Estate Activity During the Six Months Ended June 30, 2013 (Narrative) (Details) $ in Thousands								1 Months Ended	3 Months Ended				6 Months Ended
	May 31, 2013 ft² partners	Mar. 29, 2013 USD ($) ft²	Mar. 26, 2013 USD ($) ft² floor	Feb. 26, 2013	Feb. 20, 2013 USD ($)	Feb. 07, 2013	Feb. 06, 2013 USD ($) ft² floor	Jun. 30, 2013 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2013 USD ($)	Mar. 31, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 14, 2013 ft²	Apr. 25, 2013 ft²	Apr. 10, 2013 USD ($) ft² Buildings	Mar. 28, 2013 USD ($) ft²	Mar. 22, 2013 ft²
Real Estate Properties [Line Items]
Revenues										$ 515,320		$ 471,349	$ 998,334	$ 915,042
Operating income										170,815		173,319	301,250	316,886
Purchase price													522,900	621,359
Gain on forgiveness of debt from discontinued operations										0		0	20,182	0
Impairment loss from discontinued operations										0		0	3,241	0
Impairment loss										0		$ 0	$ 8,306	0
535 Mission [Member]
Real Estate Properties [Line Items]
Purchase price							$ 71,000
Number of floors real estate \| floor							27
Net Rentable Area \| ft²							307,000
Two Patriots Park [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																			256,000
Siz Zero One Massachusetts Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																478,000
Seventeen Cambridge Center [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²															195,000
Transbay Tower [Member]
Real Estate Properties [Line Items]
Number of floors real estate \| floor			60
Net Rentable Area \| ft²			1,400,000
Ownership Percentage			95.00%	95.00%
Payments to Acquire Land			$ 192,000
Partners Joint Venture Ownership Percentage				5.00%		50.00%
Reston Land Parcel [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²		250,000
Payments to Acquire Land		$ 27,000
Plaza at Almaden [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																		840,000
Impairment loss											$ 8,300
Montvale Center [Member]
Real Estate Properties [Line Items]
Amount of debt extinguished														25,000
Gain on forgiveness of debt from discontinued operations					$ 20,200									$ 17,800
303 Almaden Blvd [Member]
Real Estate Properties [Line Items]
Revenues										1,529
Operating income										873
Gain on forgiveness of debt from discontinued operations										0
Net Rentable Area \| ft²																		158,000
Impairment loss from discontinued operations										$ 0	$ 3,200
Contractual Sales Price																		$ 40,000
Mountain View Research And Technology Parks [Member]
Real Estate Properties [Line Items]
Revenues									$ 5,200
Operating income									$ (300)
Aggregate purchase price																	$ 233,500
Mountain View Research [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																	604,000
Number of real estate properties \| Buildings																	16
Mountain View Technology [Member]
Real Estate Properties [Line Items]
Net Rentable Area \| ft²																	135,000
Number of real estate properties \| Buildings																	7
767 Fifth Avenue (The GM Building) [Member]
Real Estate Properties [Line Items]
Revenues								$ 22,600
Operating income								$ 400
Number of Joint Venture Partners \| partners	2
Net Rentable Area \| ft²	1,800,000
Ownership Percentage	40.00%

Real Estate Activity During the Six Months Ended June 30, 2013 Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition (Details) - USD ($)
$ in Thousands

6 Months Ended

May 31, 2013

Apr. 10, 2013

Jun. 30, 2013

Jun. 30, 2012

Dec. 31, 2012

Business Acquisition [Line Items]

Real estate and realted intangibles recorded upon consolidation

$ 3,356,000

$ 0

Mortgage notes payable

4,484,657

$ 3,102,485

Mezzanine notes payable

311,637

Related party notes payable

(180,000)

Debt recorded upon consolidation

2,056,000

Cash and cash equivalents

79,468

Accrued interest payable

(141,676)

$ (72,461)

Working capital recorded upon consolidation

91,280

Noncontrolling interest recorded upon consolidation

$ (483,488)

$ 0

767 Fifth Avenue (The GM Building) [Member]

Business Acquisition [Line Items]

Land

$ 1,796,252

Building and Improvements

1,447,446

85,208

357,781

101,897

(239,641)

Above market assumed debt adjustments

(192,943)

Real estate and realted intangibles recorded upon consolidation

3,356,000

Mortgage notes payable

1,300,000

Mezzanine notes payable

306,000

Related party notes payable

^[1]

(450,000)

Debt recorded upon consolidation

2,056,000

Cash and cash equivalents

79,468

Cash held in escrows

2,403

Tenant and other receivables

7,104

Prepaid expense and other assets

4,269

Accounts payable and accrued expenses

(2,418)

Accrued interest payable

^[2]

(175,802)

Other Liabilities

(6,304)

Working capital recorded upon consolidation

(91,280)

Noncontrolling Interet

(520,000)

Noncontrolling interet working capital

36,512

Noncontrolling interest recorded upon consolidation

(483,488)

Net assets recorded upon consolidation

725,232

Mountain View Research And Technology Parks [Member]

Business Acquisition [Line Items]

Land

$ 126,521

Building and Improvements

82,451

7,326

23,279

843

(7,336)

$ 233,084

Consolidation, Eliminations [Member] | 767 Fifth Avenue (The GM Building) [Member]

Business Acquisition [Line Items]

Related party notes payable

(270,000)

Accrued interest payable

$ (105,500)

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

Real Estate Activity During the Six Months Ended June 30, 2013 (Summary Of The Discontinued Operations Related To Montvale Center, 303 Almaden Blvd and Bedford Business Park) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue	$ 515,320		$ 471,349	$ 998,334	$ 915,042
Expenses
Depreciation and amortization	134,604		111,168	255,199	219,630
Total expenses	344,505		298,030	697,084	598,156
Operating income	170,815		173,319	301,250	316,886
Other expense
Interest expense	(103,140)		(99,901)	(203,573)	(203,138)
Income from discontinued operations	873		218	934	788
Noncontrolling interest in income (loss) from discontinued operations - common units of the Operating Partnership	(88)		(4,075)	(1,900)	(4,159)
Income (loss) from discontinued operations attributable to Boston Properties, Inc.	785		33,020	15,975	33,506
Gain on sale of real estate from discontinued operations	0		36,877	0	36,877
Gain on forgiveness of debt from discontinued operations	0		0	20,182	0
Impairment loss from discontinued operations	0		0	3,241	0
Montvale Center and 303 Almaden Blvd [Member] [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue				3,376
Expenses
Operating				1,486
Depreciation and amortization				596
Total expenses				2,082
Operating income				1,294
Other expense
Interest expense				(360)
Income from discontinued operations				934
Noncontrolling interest in income (loss) from discontinued operations - common units of the Operating Partnership				(94)
Income (loss) from discontinued operations attributable to Boston Properties, Inc.				840
Gain on sale of real estate from discontinued operations				0
Gain on forgiveness of debt from discontinued operations				20,182
Impairment loss from discontinued operations				3,241
Noncontrolling interest in gain on the sale of real estate, gain on forgiveness of debt from discontinued operations - common units of the Operating Partnership				1,806
Gain on Sale of Real Estate, Gain On Forgiveness of Debt and Impairment Losses from Discontinued Operations Attributable to Company				$ 15,135
Montvale Center, 303 Almaden Blvd and Bedford Business Park [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue			3,263		7,784
Expenses
Operating			1,489		3,392
Depreciation and amortization			907		2,310
Total expenses			2,396		5,702
Operating income			867		2,082
Other expense
Interest expense			(649)		(1,294)
Income from discontinued operations			218		788
Noncontrolling interest in income (loss) from discontinued operations - common units of the Operating Partnership			(23)		(84)
Income (loss) from discontinued operations attributable to Boston Properties, Inc.			195		704
Gain on sale of real estate from discontinued operations			36,877		36,877
Gain on forgiveness of debt from discontinued operations			0		0
Impairment loss from discontinued operations			0		0
Noncontrolling interest in gain on the sale of real estate, gain on forgiveness of debt from discontinued operations - common units of the Operating Partnership			4,052		4,075
Gain on Sale of Real Estate, Gain On Forgiveness of Debt and Impairment Losses from Discontinued Operations Attributable to Company			$ 32,825		$ 32,802
303 Almaden Blvd [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue	1,529
Expenses
Operating	656
Depreciation and amortization	0
Total expenses	656
Operating income	873
Other expense
Interest expense	0
Income from discontinued operations	873
Noncontrolling interest in income (loss) from discontinued operations - common units of the Operating Partnership	(88)
Income (loss) from discontinued operations attributable to Boston Properties, Inc.	785
Gain on sale of real estate from discontinued operations	0
Gain on forgiveness of debt from discontinued operations	0
Impairment loss from discontinued operations	0	$ 3,200
Noncontrolling interest in gain on the sale of real estate, gain on forgiveness of debt from discontinued operations - common units of the Operating Partnership	0
Gain on Sale of Real Estate, Gain On Forgiveness of Debt and Impairment Losses from Discontinued Operations Attributable to Company	$ 0

Real Estate Activity During the Six Months Ended June 30, 2013 Business Acquistion Pro Forma (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	May 31, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Business Acquisition [Line Items]
Total revenue				$ 1,119,893	$ 1,065,877
Income from continuing operations				147,627	508,812
Net income attributable to Boston Properties, Inc.				$ 154,077	$ 501,060
Basic earnings per share, Net income attributable to Boston Properties, Inc. (dollars per share)				$ 1.00	$ 3.33
Diluted earnings per share, Net income attributable to Boston Properties, Inc. (dollars per share)				$ 0.99	$ 3.32
Gain on consolidation of joint ventures		$ 387,801	$ 0	$ 387,801	$ 0
Mountain View Research And Technology Parks [Member]
Business Acquisition [Line Items]
Gain on consolidation of joint ventures					24,400
767 Fifth Avenue (The GM Building) [Member]
Business Acquisition [Line Items]
Gain on consolidation of joint ventures	$ 363,400				$ 363,400

Investment in unconsolidated Joint Ventures (Narrative) (Details) $ in Thousands						3 Months Ended		6 Months Ended
	Jun. 05, 2013 USD ($)	May 31, 2013 USD ($) ft² partners	May 30, 2013 USD ($)	Apr. 10, 2013 USD ($) ft²	Apr. 04, 2013 USD ($) yr	Jun. 30, 2013 USD ($) ft²	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($) ft²	Jun. 30, 2012 USD ($)	Feb. 28, 2013 ft²
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Equity Method Investments								$ 201,182	$ 3,057
Losses from early extinguishment of debt						$ (152)	$ (274)	(152)	(1,041)
Gain on consolidation of joint ventures						$ 387,801	$ 0	387,801	0
Repayments of Secured Debt								$ 79,865	219,865
125 West 55th Street [Member]
Schedule of Equity Method Investments [Line Items]
Contractual Sales Price				$ 470,000
Carrying Value of Debt Assumed in Sale			$ 198,600
Maturity date			Mar. 10, 2020
Proceeds from Sale of Equity Method Investments			$ 253,700
Coupon/Stated Rate			6.09%
Equity Method Investment, Ownership Percentage				60.00%
Net Rentable Area \| ft²				588,000
Gain on sale or real estate			$ 43,300
Annapolis Junction Building Six [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage										50.00%
Net Rentable Area \| ft²										119,000
500 North Capitol [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 1.65%
Equity Method Investment, Ownership Percentage		30.00%				30.00%		30.00%
Net Rentable Area \| ft²						231,000		231,000
Annapolis Junction Building Seven [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Basis Spread on Variable Rate					1.65%
Maturity date					Apr. 04, 2016
Equity Method Investment, Ownership Percentage					50.00%
Construction Loan Facility Borrowing Capacity					$ 22,000
Number of extensions					2
Extension Option (in years) \| yr					1
Mountain View Research [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.00%
Maturity date				May 31, 2014
Debt Instrument, Description of Variable Rate Basis				LIBOR plus 2.00%
Mountain View Technology [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.50%
Maturity date				Nov. 22, 2014
Debt Instrument, Description of Variable Rate Basis				LIBOR plus 2.50%
Mountain View Research And Technology Parks [Member]
Schedule of Equity Method Investments [Line Items]
Losses from early extinguishment of debt				$ 400
Gain on consolidation of joint ventures				24,400
540 Madison Avenue [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis	LIBOR plus 1.50%
Equity Method Investment, Ownership Percentage	60.00%
Company [Member]
Schedule of Equity Method Investments [Line Items]
Losses from early extinguishment of debt				$ 200
Company [Member] \| 125 West 55th Street [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Equity Method Investments			$ 152,200
Mountain View Research And Technology Parks [Member]
Schedule of Equity Method Investments [Line Items]
Ownerhip upon acquistion				100.00%
767 Fifth Avenue (The GM Building) [Member]
Schedule of Equity Method Investments [Line Items]
Number of Joint Venture Partners \| partners		2
Gain on consolidation of joint ventures		$ 363,400							$ 363,400
Net Rentable Area \| ft²		1,800,000
Mountain View Technology [Member]
Schedule of Equity Method Investments [Line Items]
Repayments of Notes Payable				$ 3,700
Repayments of Secured Debt				20,000
Mountain View Research [Member]
Schedule of Equity Method Investments [Line Items]
Repayments of Notes Payable				8,600
Repayments of Secured Debt				$ 90,000
Construction Loans [Member] \| 500 North Capitol [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.65%
Maturity date		Oct. 14, 2014
Losses from early extinguishment of debt		$ 1,000
Repayments of Secured Debt		90,600
Construction Loans [Member] \| Company [Member] \| 500 North Capitol [Member]
Schedule of Equity Method Investments [Line Items]
Losses from early extinguishment of debt		$ 300
First Mortgage [Member] \| 500 North Capitol [Member]
Schedule of Equity Method Investments [Line Items]
Maturity date		Jun. 06, 2023
Proceeds from Issuance of Secured Debt		$ 105,000
Coupon/Stated Rate		4.15%
First Mortgage [Member] \| 540 Madison Avenue [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Maturity date	Jun. 05, 2018
Proceeds from Issuance of Secured Debt	$ 120,000
Prior to refinance first mortgage loan [Member] \| 540 Madison Avenue [Member]
Schedule of Equity Method Investments [Line Items]
Maturity date	Jul. 11, 2013
Losses from early extinguishment of debt	$ 300
Coupon/Stated Rate	5.20%
Repayments of Secured Debt	$ 118,000
Prior to refinance first mortgage loan [Member] \| Company [Member] \| 540 Madison Avenue [Member]
Schedule of Equity Method Investments [Line Items]
Losses from early extinguishment of debt	$ 200

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

6 Months Ended

Jun. 30, 2013

Land_Parcels

Buildings

Square 407 Limited Partnership [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Market Square North

Equity Method Investment, Ownership Percentage

50.00%

The Metropolitan Square Associates LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Metropolitan Square

Equity Method Investment, Ownership Percentage

51.00%

BP/CRF 901 New York Avenue LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

901 New York Avenue

^[1]

Equity Method Investment, Ownership Percentage

25.00%

^[1]

WP Project Developer LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Wisconsin Place Land and Infrastructure

^[2]

Equity Method Investment, Ownership Percentage

33.30%

^[2]

RBP Joint Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Eighth Avenue and 46th Street

^[3]

Equity Method Investment, Ownership Percentage

50.00%

^[3]

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

Schedule of Equity Method Investments [Line Items]

Properties

N/A

^[4]

Equity Method Investment, Ownership Percentage

39.50%

^[4]

Annapolis Junction NFM, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Annapolis Junction

^[5]

Equity Method Investment, Ownership Percentage

50.00%

^[5]

Number of real estate properties

Number of buildings under construction

Parcels of undeveloped land | Land_Parcels

2 GCT Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

N/A

^[6]

Equity Method Investment, Ownership Percentage

60.00%

^[6]

540 Madison Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

540 Madison Avenue

Equity Method Investment, Ownership Percentage

60.00%

125 West 55th Street Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

N/A

^[7]

Equity Method Investment, Ownership Percentage

60.00%

^[7]

500 North Capitol LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

500 North Capitol Street, NW

Equity Method Investment, Ownership Percentage

30.00%

Entity Owning Land And Infrastructure Of Project [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

33.30%

[1]	The Company’s economic ownership can increase based on the achievement of certain return thresholds.
[2]	The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land and infrastructure of the project.
[3]	See Note 14.
[4]	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of June 30, 2013, the investment is comprised of undistributed cash.
[5]	Comprised of two buildings, one building under construction and two undeveloped land parcels.
[6]	Two Grand Central Tower was sold on October 25, 2011. As of June 30, 2013, the investment is comprised of undistributed cash.
[7]	125 West 55th Street was sold on May 30, 2013. As of June 30, 2013, the investment is comprised of undistributed cash.

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

Jun. 30, 2013

Dec. 31, 2012

Schedule of Equity Method Investments [Line Items]

Real estate and development in process, net

$ 15,835,914

$ 11,959,168

Mortgage notes payable

4,484,657

3,102,485

Other liabilities

556,730

324,613

Total liabilities and equity

19,462,784

15,462,321

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

137,975

659,916

Unconsolidated Joint Ventures [Member]

Schedule of Equity Method Investments [Line Items]

Real estate and development in process, net

949,193

4,494,971

Other assets

162,065

673,716

Total assets

1,111,258

5,168,687

Mortgage notes payable

745,550

3,039,922

Other liabilities

25,756

792,888

Members'/Partners' equity

339,952

1,335,877

Total liabilities and equity

1,111,258

5,168,687

Company's share of equity

167,225

787,941

Basis differentials

^[1]

(29,250)

(128,025)

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

$ 137,975

$ 659,916

[1]

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

3 Months Ended

6 Months Ended

Jun. 30, 2013

Jun. 30, 2012

Jun. 30, 2013

Jun. 30, 2012

Schedule of Equity Method Investments [Line Items]

Total revenue

$ 515,320

$ 471,349

$ 998,334

$ 915,042

Expenses

Depreciation and amortization

134,604

111,168

255,199

219,630

Total expenses

344,505

298,030

697,084

598,156

Operating income

170,815

173,319

301,250

316,886

Other expense

Interest expense

(103,140)

(99,901)

(203,573)

(203,138)

Losses on Extinguishment of Debt

152

274

152

1,041

Income from continuing operations

505,888

97,079

546,817

152,344

Net income

506,761

134,174

564,692

190,009

Income from unconsolidated joint ventures

48,783

21,191

57,504

32,912

Gain on consolidation of joint ventures

387,801

Unconsolidated Joint Ventures [Member]

Schedule of Equity Method Investments [Line Items]

Total revenue

^[1]

99,831

156,035

235,481

295,135

Expenses

Operating

32,497

39,261

74,863

78,153

Depreciation and amortization

27,141

42,679

66,418

84,578

Total expenses

59,638

81,940

141,281

162,731

Operating income

40,193

74,095

94,200

132,404

Other expense

Interest expense

(40,054)

(55,909)

(96,288)

(111,271)

Losses on Extinguishment of Debt

(1,677)

Income from continuing operations

(1,538)

18,186

(3,765)

21,133

Gain on sale of real estate

1,766

Net income

228

18,186

(1,999)

21,133

Company's share of net income (loss)

683

10,641

(1,175)

12,012

Gain on sale or real estate

43,327

Basis differential

(2,070)

431

(1,626)

897

Elimination of inter-entity interest on partner loan

6,843

10,119

16,978

20,003

Income from unconsolidated joint ventures

48,783

21,191

57,504

32,912

Straight-line rent adjustments

3,100

2,800

(7,100)

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

13,500

23,200

34,000

48,500

Termination income

19,600

Company Share Of Termination Income

11,800

Gain on consolidation of joint ventures

$ 387,801

$ 0

$ 387,801

$ 0

[1]

Mortgage Notes Payable (Narrative) (Details) - USD ($)				3 Months Ended		6 Months Ended
Mortgage Notes Payable (Narrative) (Details) - USD ($)	May 31, 2013	Feb. 20, 2013	Feb. 05, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Mortgage Notes Payable [Line Items]
Repayments of Secured Debt						$ 79,865,000	$ 219,865,000
Gains from early extinguishments of debt				$ 152,000	$ 274,000	152,000	1,041,000
Gain on forgiveness of debt from discontinued operations				0	$ 0	20,182,000	0
Accrued interest payable				141,676,000		141,676,000		$ 72,461,000
Related party notes payable				180,000,000		$ 180,000,000		$ 0
Montvale Center [Member]
Mortgage Notes Payable [Line Items]
Amount of debt extinguished							25,000,000
Gain on forgiveness of debt from discontinued operations		$ 20,200,000					$ 17,800,000
Kingstowne One [Member]
Mortgage Notes Payable [Line Items]
Repayments of Secured Debt			$ 17,000,000
Coupon/Stated Rate			5.96%
Maturity date			May 05, 2013
Penalty For Early Repayment Of Debt			$ 0.0
140 Kendrick [Member]
Mortgage Notes Payable [Line Items]
Repayments of Secured Debt				$ 47,600,000
Coupon/Stated Rate				7.51%		7.51%
Maturity date				Jul. 01, 2013
Penalty For Early Repayment Of Debt				$ 0
Gains from early extinguishments of debt				300,000
767 Fifth Avenue (The GM Building) [Member]
Mortgage Notes Payable [Line Items]
Coupon/Stated Rate	11.00%
Maturity date	Jun. 09, 2017
MortgageLoans Accounted For At Fair Value Upon Consolidation	$ 1,500,000,000
Accrued interest payable				$ 175,800,000		$ 175,800,000
Related party notes payable	$ 450,000,000
First Mortgage [Member] \| 767 Fifth Avenue (The GM Building) [Member]
Mortgage Notes Payable [Line Items]
Coupon/Stated Rate	5.95%
Maturity date	Oct. 07, 2017
Asssumed debt	$ 1,300,000,000
Interest Rate Used To Account For Mortgage Loan At Fai rValue Upon Consolidation	2.44%
Subordinated Debt [Member] \| 767 Fifth Avenue (The GM Building) [Member]
Mortgage Notes Payable [Line Items]
Coupon/Stated Rate	6.02%
Maturity date	Oct. 07, 2017
Asssumed debt	$ 306,000,000
MortgageLoans Accounted For At Fair Value Upon Consolidation	$ 311,700,000
Interest Rate Used To Account For Mortgage Loan At Fai rValue Upon Consolidation	5.53%
Consolidation, Eliminations [Member] \| 767 Fifth Avenue (The GM Building) [Member]
Mortgage Notes Payable [Line Items]
Related party notes payable	$ 270,000,000
Company [Member] \| 767 Fifth Avenue (The GM Building) [Member]
Mortgage Notes Payable [Line Items]
Related party notes payable	$ 180,000,000

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

6 Months Ended

Jun. 27, 2013

Apr. 11, 2013

Jun. 30, 2013

Jun. 30, 2012

Debt Instrument [Line Items]

Proceeds from Issuance of Unsecured Debt

$ 1,194,753

$ 997,790

Senior Notes [Member]

Debt Instrument [Line Items]

Maximum Leverage Ratio

60.00%

Maximum Secured Debt Leverage Ratio

50.00%

Minimum Interest Coverage Ratio

1.50

Minimum Unencumbered Asset Value Percentage Of Unsecured Debt

150.00%

3.279% Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Proceeds from Issuance of Unsecured Debt

$ 492,500

Debt Instrument, Face Amount

$ 500,000

Coupon/Stated Rate

3.125%

Senior Notes Pricing

99.379%

Effective Percentage

3.279%

^[1]

Debt Instrument, Maturity Date

Sep. 01, 2023

^[2]

3.916%t Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Proceeds from Issuance of Unsecured Debt

$ 691,900

Debt Instrument, Face Amount

$ 700,000

Coupon/Stated Rate

3.80%

Senior Notes Pricing

99.694%

Effective Percentage

3.916%

^[1]

Debt Instrument, Maturity Date

Feb. 01, 2024

^[2]

[1]	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.
[2]	No principal amounts are due prior to maturity.

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

6 Months Ended

Jun. 27, 2013

Apr. 11, 2013

Jun. 30, 2013

Dec. 31, 2012

Debt Instrument [Line Items]

Unsecured senior notes, discount

$ 15,027

$ 10,472

Unsecured senior notes

$ 5,834,973

$ 4,639,528

5.693% unsecured senior notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

5.625%

Effective Percentage

^[1]

5.693%

Principal Amount

$ 300,000

Maturity date

^[2]

Apr. 15, 2015

5.194% Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

5.00%

Effective Percentage

^[1]

5.194%

Principal Amount

$ 250,000

Maturity date

^[2]

Jun. 01, 2015

5.967%t unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

5.875%

Effective Percentage

^[1]

5.967%

Principal Amount

$ 700,000

Maturity date

^[2]

Oct. 15, 2019

5.708% Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

5.625%

Effective Percentage

^[1]

5.708%

Principal Amount

$ 700,000

Maturity date

^[2]

Nov. 15, 2020

4.289% Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

4.125%

Effective Percentage

^[1]

4.289%

Principal Amount

$ 850,000

Maturity date

^[2]

May 15, 2021

3.853% Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

3.70%

Effective Percentage

^[1]

3.853%

Principal Amount

$ 850,000

Maturity date

^[2]

Nov. 15, 2018

3.954% Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

3.85%

Effective Percentage

^[1]

3.954%

Principal Amount

$ 1,000,000

Maturity date

^[2]

Feb. 01, 2023

3.279% Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

3.125%

Effective Percentage

3.279%

^[1]

Principal Amount

$ 500,000

Maturity date

Sep. 01, 2023

^[2]

3.916%t Unsecured Senior Notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

3.80%

Effective Percentage

3.916%

^[1]

Principal Amount

$ 700,000

Maturity date

Feb. 01, 2024

^[2]

Senior Notes [Member]

Debt Instrument [Line Items]

Principal Amount

$ 5,850,000

Unsecured senior notes, discount

(15,027)

Unsecured senior notes

$ 5,834,973

[1]	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.
[2]	No principal amounts are due prior to maturity.

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

6 Months Ended

Jun. 30, 2013

USD ($)

$ / shares

Dec. 31, 2012

USD ($)

Aug. 15, 2008

$ / shares

Debt Instrument [Line Items]

Unsecured exchangeable senior notes, discount

$ (924,000)

$ (1,653,000)

Adjustment for the equity component allocation, net of accumulated amortization

(12,298,000)

Unsecured exchangeable senior notes

734,278,000

$ 1,170,356,000

Increment Of The Notes For Purposes Of Disclosing Initial Exchange Rate

$ 1,000

Initial Exchange Rate

8.5051

Debt Instrument, Convertible, Conversion Price | $ / shares

$ 117.58

Adjusted Exchange Price Due To Capped Call | $ / shares

$ 137.17

Premium Over Closing Price Due To Capped Call

40.00%

Share Price | $ / shares

$ 134.38

$ 97.98

Net Cost Of Capped Call Transaction

$ 44,400,000

3.625% exchangeable senior notes [Member]

Debt Instrument [Line Items]

Coupon/Stated Rate

3.625%

Effective Percentage

^[1]

4.037%

Exchange Rrate

^[2]

8.5051

Principal Amount

$ 747,500,000

Maturity date

Feb. 15, 2014

[1]

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

[2]

Unsecured Exchangeable Senior Notes Unsecured Exchangeable Senior Notes (Narrative) (details) - USD ($)		3 Months Ended		6 Months Ended
	May 18, 2013	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Debt Instrument [Line Items]
Shares issued as part of the exchange		152,463,640		152,463,640		151,680,119
Losses from early extinguishment of debt		$ (152,000)	$ (274,000)	$ (152,000)	$ (1,041,000)
3.75% xchangeable Senior Notes [Member]
Debt Instrument [Line Items]
Coupon/Stated Rate	3.75%
Redemption Date	May 18, 2013
Debt Instrument Redemption Price Principal Percentage	100.00%
Shares issued as part of the exchange	419,116
Losses from early extinguishment of debt	$ 100,000
3.75% xchangeable Senior Notes [Member] \| Redeemed amount [Member]
Debt Instrument [Line Items]
Repayments of Unsecured Debt	990,000
3.75% xchangeable Senior Notes [Member] \| Submitted for Exchange [Member]
Debt Instrument [Line Items]
Repayments of Unsecured Debt	$ 449,010,000

Commitments And Contingencies (Details) $ in Millions	6 Months Ended
Commitments And Contingencies (Details) $ in Millions	Jun. 30, 2013 USD ($)
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations	$ 13.9
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
Earthquake Coverage Included in Builders Risk Policy for 680 Folsom	20.0
Earthquake Coverage Included In Builders Risk Policy For 535 Mission	15.0
Operating partnership guarantee to cover liabilities of IXP	20.0
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation	28.2
Property insurance program per occurrence limits	1,625.0
Coverage for acts of Terrorism certified under TRIA in excess of amount provided by NYXP, LLC, as a direct insurer	1,375.0
Coverage for acts of terrorism certified under TRIA	250.0
John Hancock Tower [Member]
Commitments And Contingencies [Line Items]
Guarantee Obligation Related To Tenant Re-Leasing Costs	4.2
601 Lexington Avenue [Member]
Commitments And Contingencies [Line Items]
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP	$ 250.0

Noncontrolling Interests (Narrative) (Details)	Jun. 30, 2013 shares
Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Operating Partnership (OP) Units (in shares)	15,739,523
Long-Term Incentive Plan (LTIP) Units (in shares)	1,464,250
Series Two Preferred Units (in shares)	995,997
Convertible Operating Partnership (OP) Units (in shares)	1,307,083
Series Four Preferred Units (in shares)	1,221,527
OPP Units 2011 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	397,750
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	397,750
MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2013 MYLTIP	317,406

Noncontrolling Interests (Redeemable Preferred Units) (Narrative) (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2013 $ / shares shares	Jun. 30, 2013 $ / shares shares	Aug. 07, 2013 $ / shares	May 29, 2013 d	May 15, 2013 $ / shares	May 14, 2013	Feb. 15, 2013 $ / shares	Dec. 31, 2012	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 (in shares) \| shares	995,997	995,997
Series Four Preferred Units (in shares) \| shares	1,221,527	1,221,527
Series Two Preferred Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Preferred Units Liquidation Preference	$ 50.00	$ 50.00
OP Units for each Preferred Unit (in shares) \| shares	1.312336
Series Two Preferred Units [Member] \| Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Series Two Preferred Units (in shares) \| shares	995,997	995,997
Liquidation preference percentage		6.00%
Preferred Units Liquidation Preference	$ 50.00	$ 50.00
Operating Units liquidation preference (in dollars per share)	38.10	$ 38.10
OP Units for each Preferred Unit (in shares) \| shares		1.312336
Distributions to Series Two Preferred Units (in dollars per share)					$ 0.85302		$ 0.85302
Number Of Holders Exercises						0		0	0	0	0
series four preferred units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Preferred Units Liquidation Preference	$ 50.00	$ 50.00	$ 50.00
Series Four Preferred Units Annual Dividend Payable Rate	2.00%
series four preferred units [Member] \| Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Preferred Units Liquidation Preference	$ 50.00	$ 50.00
First opportunity to redeem Series Four Preferred Units (in days) \| d				30
Distributions to Series Two Preferred Units (in dollars per share)					$ 0.25		$ 0.25
Series Four Preferred Units (in shares) \| shares	1,221,527	1,221,527
Series Four Preferred Units Annual Dividend Payable Rate		2.00%
Redemption Year Two Thousand Fourteen [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Maximum Redeemable On Redemption Dates Preferred Units \| shares	1,007,662	1,007,662
Series Two Preferred Units Redemption Price	$ 50.00	$ 50.00
Dates Series Two Preferred Unit Holders Can Require Redemption From Operating Partnership		May 12, 2014
Maximum portion that may be required for redemption of total		0.1666666667

Noncontrolling Interests (Redeemable Preferred Units) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning Balance			$ 110,876
Net Income	$ 1,123	$ 765	2,303	$ 1,566
Conversion of redeemable preferred units (Series Two Preferred Units) to common units				4,115
Ending Balance	110,876		110,876
Redeemable Preferred Units [Member]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning Balance			110,876	55,652
Net Income			2,303	1,566
Distributions			(2,303)	(1,566)
Conversion of redeemable preferred units (Series Two Preferred Units) to common units				(4,115)
Ending Balance	$ 110,876	$ 51,537	$ 110,876	$ 51,537

(Common Units) (Narrative) (Details) $ / shares in Units, $ in Millions			6 Months Ended
	Apr. 30, 2013 $ / shares	Jan. 29, 2013 $ / shares	Jun. 30, 2013 USD ($) yr $ / shares shares	Jun. 18, 2013 $ / shares
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares) \| shares			333,997
Redemption of OP units issued on conversion of LTIP Units (in shares) \| shares			17,651
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 (in dollars per share) \| $ / shares	$ 0.65	$ 0.65
Distribution paid to outperformance awards, OPP Units (in dollars per share) \| $ / shares	$ 0.065	$ 0.065
Distribution declared to OP and LTIP units by Boston Properties, Inc. (in dollars per share) \| $ / shares				$ 0.65
Distribution declared to outperformance awards OPP Units by Boston Properties, Inc. (in dollars per share) \| $ / shares				$ 0.065
Restriction on redemption of OP Unit to Common Stock (in years) \| yr			1
Redemption of OP Unit equivalence to Common Stock (in shares) \| shares			1
Common units of operating partnership if converted value \| $			$ 1,800.0
Value of Series Two Preferred Units assuming conversion \| $			$ 137.9
OPP Units 2011 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares) \| shares			397,750
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares) \| shares			397,750
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Closing price of common stock (in dollars per share) \| $ / shares			$ 105.47
Quarter 4 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date			Jan. 29, 2013
Quarter 4 2012 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date			Jan. 29, 2013
Holders of record date			Dec. 31, 2012
Quarter 1 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date			Apr. 30, 2013
Quarter 1 2013 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date			Apr. 30, 2013
Holders of record date			Mar. 29, 2013
Quarter 2 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date			Jul. 31, 2013
Dividends payable, date declared			Jun. 18, 2013
Quarter 2 2013 [Member] \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date			Jul. 31, 2013
Holders of record date			Jun. 28, 2013
Dividends payable, date declared			Jun. 18, 2013

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) $ in Thousands, ft² in Millions					6 Months Ended
	May 31, 2013 USD ($) ft² partners	Mar. 26, 2013 USD ($) ft² floor	Feb. 26, 2013	Feb. 07, 2013	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Dec. 31, 2012 USD ($)
Noncontrolling Interest [Line Items]
Property partnerships					$ 489,389		$ (1,964)
Noncontrolling interest recorded upon consolidation					$ 483,488	$ 0
Transbay Tower [Member]
Noncontrolling Interest [Line Items]
Partners Joint Venture Ownership Percentage			5.00%	50.00%
Ownership Percentage		95.00%	95.00%
Number of floors real estate \| floor		60
Net Rentable Area \| ft²		1.4
Payments to Acquire Land		$ 192,000
767 Fifth Avenue (The GM Building) [Member]
Noncontrolling Interest [Line Items]
Ownership Percentage	40.00%
Net Rentable Area \| ft²	1.8
Number of Joint Venture Partners \| partners	2
Noncontrolling interest recorded upon consolidation	$ 483,488

Noncontrolling Interests Noncontrolling Redeemable Property Partnerships (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2013 USD ($)
Noncontrolling Interest Redeemable Property Partnership [Abstract]
Beginning Balance	$ 97,558
Net Loss for Redeemable interest in Property Partnership	(980)
Distributions on Redeemable Property Partnership	(2,950)
Adjustment to Reflect Redeemable Interest at Redemption Value	4,534
Ending Balance	$ 98,162

Noncontrolling Interests Redeemable interest in proty partnership (Narrative) (Details) - Fountain Square [Member] $ in Millions	Oct. 04, 2012 USD ($)
Noncontrolling Interest [Line Items]
Aggregate purchase price	$ 385.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	$ 211.3
Ownership Percentage	50.00%
Cash contributed	$ 87.0
Noncontrolling Interest, Ownership Percentage by Parent	50.00%
Future Fixed Price to Acquire Remaining Portion of Joint venture	$ 102.0
Fixed Price Option Expiration Date	Jan. 31, 2016

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands					6 Months Ended	60 Months Ended
	May 15, 2013	Apr. 30, 2013	Mar. 27, 2013	Jan. 29, 2013	Jun. 30, 2013	Mar. 26, 2018	Mar. 27, 2018	Jun. 18, 2013	Dec. 31, 2012
Class of Stock [Line Items]
Common stock, shares outstanding					152,384,740				151,601,209
Shares of its Common Stock in connection with the redemption of an equal number of OP Units					333,997
Dividend paid on common stock (in dollars per share)		$ 0.65		$ 0.65
Dividends Payable, Amount Per Share								$ 0.65
Proceeds from Issuance of Series B			$ 193,900		$ 193,920
Atm Program [Member]
Class of Stock [Line Items]
At the market stock offering program, aggregate value of common stock					600,000
At the market stock offering program remaining amount available for issuance					$ 305,300
Issued in conjunction with debt exchange for 3.75% exchangeable senior notes [Member]
Class of Stock [Line Items]
Shares issued in conjunction with exchange of 3.75% exchangeable senior notes					419,116
Coupon/Stated Rate					3.75%
Quarter 4 2012 [Member]
Class of Stock [Line Items]
Dividend payable date					Jan. 29, 2013
Dividend shareholder of record date					Dec. 31, 2012
Quarter 1 2013 [Member]
Class of Stock [Line Items]
Dividend payable date					Apr. 30, 2013
Dividend shareholder of record date					Mar. 29, 2013
Quarter 2 2013 [Member]
Class of Stock [Line Items]
Dividend payable date					Jul. 31, 2013
Dividend shareholder of record date					Jun. 28, 2013
Dividends payable, date declared					Jun. 18, 2013
Series B Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Dividend paid on common stock (in dollars per share)	$ 17.8646
Dividends Payable, Amount Per Share								$ 32.8125
Series B, Shares Outstanding					80,000				0
Series B, Dividend Rate, Percentage						5.25%
Series B, Liquidation Preference Per Share					$ 2,500.00		$ 2,500.00		$ 0
Ratio of depository shares to shares of Series B Preferred Stock					0.01
Series B Cumulative Redeemable Preferred Stock [Member] \| Quarter 2 2013 [Member]
Class of Stock [Line Items]
Dividend payable date					May 15, 2013
Series B Cumulative Redeemable Preferred Stock [Member] \| Quarter 3 2013 [Member]
Class of Stock [Line Items]
Dividend payable date					Aug. 15, 2013
Dividend shareholder of record date					Aug. 05, 2013
Dividends payable, date declared					Jun. 18, 2013
Depository shares of Series B Cumulative Redeemable Preferred [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding					8,000,000
Series B, Liquidation Preference Per Share					$ 25.00		$ 25.00

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basic Earnings:
Income from continuing operations attributable to Boston Properties, Inc., Income (Numerator)	$ 451,632	$ 85,539	$ 484,118	$ 133,465
Net income attributable to Boston Properties Inc., Shares (Denominator)	151,938	150,312	151,793	149,328
Inceom (loss) from continuing operations before discontinued operations and allocation of undistributed earnings (dollars per share)	$ 2.97		$ 3.19
Income from continuing operations attributable to Boston Properties, Inc., Per Share Amount (in dollars per share)	$ 2.94	$ 0.57	$ 3.17	$ 0.89
Discontinued operations attributable to Boston Properties, Inc., Income (Numerator)	$ 785	$ 33,020	$ 15,975	$ 33,506
Discontinued operations attributable to Boston Properties, Inc., Per Share Amount (in dollars per share)	$ 0.01	$ 0.22	$ 0.10	$ 0.23
Allocation of undistributed earnings to participating securities (numberator)	$ (3,629)		$ (3,179)
Allocation of undistributed earnings to participating securities (in dollars per shares)	$ (0.03)		$ (0.02)
Net Income Loss Available To Common Stockholders After Discontinued Operations and Allocation of undistributed Earnings,Basic	$ 448,788		$ 496,914
Net Income (Loss) Available to Common Stockholders, Basic	$ 452,417	$ 118,559	$ 500,093	$ 166,971
Net income (in dollars per share)	$ 2.95	$ 0.79	$ 3.27	$ 1.12
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes, Income (Numerator)	$ 0	$ 0	$ 0	$ 0
Stock Based Compensation and Exchangeable Senior Notes, Shares (Denominator)	552	382	429	392
Stock Based Compensation and Exchangeable Senior Notes, Per Share Amount (in dollars per share)	$ (0.01)	$ (0.01)	$ (0.01)	$ 0.00
Diluted Earnings:
Diluted Earnings: Net income, Income (Numerator)	$ 448,788	$ 118,559	$ 496,914	$ 166,971
Diluted Earnings: Net income, Shares (Denominator)	152,490	150,694	152,222	149,720
Diluted Earnings: Net income, Per Share Amount (in dollars per share)	$ 2.94	$ 0.78	$ 3.26	$ 1.12

Stock Option and Incentive Plan (Restricted Stock) (Narrative) (Details) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Jan. 28, 2013 yr	Jun. 30, 2013 USD ($) $ / shares shares	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($) VestingInstallments $ / shares shares	Jun. 30, 2012 USD ($)	Dec. 31, 2012 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued \| shares		152,463,640		152,463,640		151,680,119
Stock-based compensation associated with restricted stock, non-qualified options, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units and 2013 MYLTIPS		$ 6,400	$ 6,400	$ 31,900	$ 17,400
Value of shares of common stock		$ 1,524		$ 1,524		$ 1,516
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued \| shares		36,730		36,730
Employee and director payment per share (in dollars per share) \| $ / shares				$ 0.01
Value of shares of common stock		$ 3,900		$ 3,900
Employee's weighted average cost per share (in dollars per share) \| $ / shares		$ 105.30		$ 105.30
LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares) \| shares		184,733		184,733
Value of LTIP units issued				$ 14,800
Per unit fair value weighted-average (in dollars per share) \| $ / shares		$ 96.33		$ 96.33
Expected life assumed to calculate per unit fair value per LTIP unit (years)				5 years 8 months 12 days
Risk-free rate				1.03%
Expected price volatility				26.00%
Method of valuation				Monte Carlo simulation method
MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued (in shares) \| shares		318,926		318,926
TRS Measurement, Years \| yr	3
LTIPs And Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting annual installments \| VestingInstallments				4
Unrecognized compensation expenses		$ 22,900		$ 22,900
LTIPs and OPP Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share) \| $ / shares				$ 0.25
Non Qualified Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-qualified stock options issued \| shares		252,220		252,220
Expected life assumed to calculate per unit fair value per LTIP unit (years)				6 years
Risk-free rate				1.11%
Expected price volatility				26.00%
Expected dividend rate				3.00%
Method of valuation				The non-qualified stock options granted during the nine months ended March 31, 2013 had a weighted-average fair value on the date of grant of $18.64 per option, which was computed using the Black-Scholes option-pricing model utilizing the following weighted-average assumptions: an expected life of 6.3 years, a risk-free interest rate of 1.19%, an expected price volatility of 26% and an expected dividend yield of 3%.
Weighted-average grant date fair value (in dollars per share) \| $ / shares				$ 18.46
Weighted-average exercise price (in dollars per share) \| $ / shares				$ 105.10
Unvested 2011 and 2012 OPP Units and 2013 MYLTIPS [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses		$ 14,300		$ 14,300
Weighted-average period (years)				3 years
Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Acceleration of Stock Basec Compensation and Stock Based Compensation Associated with Transition Agreement				$ 18,600
Executive Vice President [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation associated with restricted stock, non-qualified options, LTIP Units, 2008 OPP Units, 2011 OPP Units, and 2012 OPP Units and 2013 MYLTIPS					$ 2,700

Stock Option and Incentive Plan Stock Option and Incentive Plan (Narrative) (Details)		3 Months Ended		6 Months Ended
	Jan. 28, 2013 USD ($) indices yr	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Mar. 11, 2013 USD ($)	Mar. 10, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense		$ 6,400,000	$ 6,400,000	$ 31,900,000	$ 17,400,000
Cash Payment Related to Transition Agreement						$ 6,700,000
MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
TRS Measurement, Years \| yr	3
Indices Used to Compare TRS \| indices	2
Number of Tiers	4
Percentage of annualized TRS for Reduction of Earned Awards	2.00%
Percentage to Cause Some Awards to be Earned Even if on a Relative Basis it Would Not Result in any Earned Awards	10.00%
Distributions Percent Before Measurement Date	10.00%
Value of MYLTIP Awards	$ 9,200,000
MYLTIP Value Amortized Into Earnings, Years \| yr	5
Cohen & Steers Realty Majors Portfolio Index [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Percentage of Index Used to Compare to TRS	50.00%
NAREIT Office Index adjusted [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Percentage of Index Used to Compare to TRS	50.00%
Minimum [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned	$ 0
Maximum [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned	30,700,000
Threshold [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier	5,100,000
Target [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier	10,200,000
High [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier	20,500,000
Exceptional [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier	$ 30,700,000
MYLTIP Vesting 2018 [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage	50.00%
Vesting Date	Feb. 04, 2018
MYLTIP Vesting 2017 [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage	25.00%
Vesting Date	Feb. 04, 2017
MYLTIP Vesting 2016 [Member] \| MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage	25.00%
Vesting Date	Feb. 04, 2016
Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage							33.33333%
Target Equity Award Compensation Associated with Transition Agreement						$ 11,100,000
Compensation Expense associated with Transition Agreement				9,200,000
Acceleration of Stock Based Compensation in Association with Transition Agreement				$ 12,900,000

Segment Information Segment Information (narrative) (Details)	May 31, 2013 partners
767 Fifth Avenue (The GM Building) [Member]
Segment Reporting Information [Line Items]
Number of Joint Venture Partners	2

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 475,965	$ 436,758	$ 926,527	$ 851,266
Rental Revenue: Office/Technical	14,896	9,942	24,743	19,685
Rental Revenue: Residential	5,484	5,036	11,062	9,517
Rental Revenue: Hotel	11,118	10,049	19,409	16,865
Total revenue	$ 507,463	$ 461,785	$ 981,741	$ 897,333
Rental Revenue: % of Grand Totals	100.00%	100.00%	100.00%	100.00%
Rental Expenses: Class A Office	$ 173,237	$ 155,944	$ 340,298	$ 306,500
Rental Expenses: Office/Technical	3,770	2,654	6,596	5,225
Rental Expenses: Residential	2,830	2,574	5,563	5,289
Rental Expenses: Hotel	7,335	6,616	14,379	12,715
Rental Expenses: Total	$ 187,172	$ 167,788	$ 366,836	$ 329,729
Rental Expenses: % Of Grand Totals	100.00%	100.00%	100.00%	100.00%
Net operating Income	$ 320,291	$ 293,997	$ 614,905	$ 567,604
Net operating Income: % of Grand Totals	100.00%	100.00%	100.00%	100.00%
Boston [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 164,855	$ 157,642	$ 326,358	$ 298,650
Rental Revenue: Office/Technical	5,538	5,744	11,191	11,343
Rental Revenue: Residential	1,065	1,013	2,132	1,896
Rental Revenue: Hotel	11,118	10,049	19,409	16,865
Total revenue	$ 182,576	$ 174,448	$ 359,090	$ 328,754
Rental Revenue: % of Grand Totals	35.98%	37.78%	36.58%	36.64%
Rental Expenses: Class A Office	$ 63,181	$ 60,504	$ 128,913	$ 118,337
Rental Expenses: Office/Technical	1,627	1,652	3,414	3,152
Rental Expenses: Residential	407	367	850	757
Rental Expenses: Hotel	7,335	6,616	14,379	12,715
Rental Expenses: Total	$ 72,550	$ 69,139	$ 147,556	$ 134,961
Rental Expenses: % Of Grand Totals	38.76%	41.21%	40.22%	40.93%
Net operating Income	$ 110,026	$ 105,309	$ 211,534	$ 193,793
Net operating Income: % of Grand Totals	34.35%	35.82%	34.40%	34.14%
New York [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 143,305	$ 122,657	$ 265,401	$ 240,246
Rental Revenue: Office/Technical	0	0	0	0
Rental Revenue: Residential	0	0	0	0
Rental Revenue: Hotel	0	0	0	0
Total revenue	$ 143,305	$ 122,657	$ 265,401	$ 240,246
Rental Revenue: % of Grand Totals	28.24%	26.56%	27.03%	26.77%
Rental Expenses: Class A Office	$ 48,205	$ 38,936	$ 90,092	$ 77,443
Rental Expenses: Office/Technical	0	0	0	0
Rental Expenses: Residential	0	0	0	0
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	$ 48,205	$ 38,936	$ 90,092	$ 77,443
Rental Expenses: % Of Grand Totals	25.75%	23.21%	24.56%	23.49%
Net operating Income	$ 95,100	$ 83,721	$ 175,309	$ 162,803
Net operating Income: % of Grand Totals	29.69%	28.48%	28.51%	28.68%
Princeton [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 14,853	$ 15,617	$ 31,280	$ 30,467
Rental Revenue: Office/Technical	0	0	0	0
Rental Revenue: Residential	0	0	0	0
Rental Revenue: Hotel	0	0	0	0
Total revenue	$ 14,853	$ 15,617	$ 31,280	$ 30,467
Rental Revenue: % of Grand Totals	2.93%	3.38%	3.19%	3.40%
Rental Expenses: Class A Office	$ 7,667	$ 7,691	$ 15,314	$ 15,049
Rental Expenses: Office/Technical	0	0	0	0
Rental Expenses: Residential	0	0	0	0
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	$ 7,667	$ 7,691	$ 15,314	$ 15,049
Rental Expenses: % Of Grand Totals	4.10%	4.58%	4.17%	4.56%
Net operating Income	$ 7,186	$ 7,926	$ 15,966	$ 15,418
Net operating Income: % of Grand Totals	2.24%	2.70%	2.60%	2.72%
San Francisco [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 53,331	$ 52,102	$ 106,002	$ 102,766
Rental Revenue: Office/Technical	5,327	144	5,478	196
Rental Revenue: Residential	0	0	0	0
Rental Revenue: Hotel	0	0	0	0
Total revenue	$ 58,658	$ 52,246	$ 111,480	$ 102,962
Rental Revenue: % of Grand Totals	11.56%	11.31%	11.35%	11.47%
Rental Expenses: Class A Office	$ 21,264	$ 20,507	$ 41,136	$ 39,924
Rental Expenses: Office/Technical	1,116	38	1,151	62
Rental Expenses: Residential	0	0	0	0
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	$ 22,380	$ 20,545	$ 42,287	$ 39,986
Rental Expenses: % Of Grand Totals	11.96%	12.24%	11.53%	12.13%
Net operating Income	$ 36,278	$ 31,701	$ 69,193	$ 62,976
Net operating Income: % of Grand Totals	11.33%	10.78%	11.25%	11.10%
Washington, DC [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 99,621	$ 88,740	$ 197,486	$ 179,137
Rental Revenue: Office/Technical	4,031	4,054	8,074	8,146
Rental Revenue: Residential	4,419	4,023	8,930	7,621
Rental Revenue: Hotel	0	0	0	0
Total revenue	$ 108,071	$ 96,817	$ 214,490	$ 194,904
Rental Revenue: % of Grand Totals	21.29%	20.97%	21.85%	21.72%
Rental Expenses: Class A Office	$ 32,920	$ 28,306	$ 64,843	$ 55,747
Rental Expenses: Office/Technical	1,027	964	2,031	2,011
Rental Expenses: Residential	2,423	2,207	4,713	4,532
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	$ 36,370	$ 31,477	$ 71,587	$ 62,290
Rental Expenses: % Of Grand Totals	19.43%	18.76%	19.52%	18.89%
Net operating Income	$ 71,701	$ 65,340	$ 142,903	$ 132,614
Net operating Income: % of Grand Totals	22.39%	22.22%	23.24%	23.36%

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Operating Income	$ 170,815	$ 173,319	$ 301,250	$ 316,886
Development and management services income	7,857	9,564	16,593	17,709
Income from unconsolidated joint ventures	48,783	21,191	57,504	32,912
Gain on consolidation of joint ventures	387,801	0	387,801	0
Interest and other income	1,296	2,382	2,767	4,028
Gains (losses) from investments in securities	181	(186)	916	615
Gains from early extinguishments of debt	152	274	152	1,041
Gain on sale of real estate from discontinued operations	0	36,877	0	36,877
Gain on forgiveness of debt from discontinued operations	0	0	20,182	0
General and administrative expense	22,194	19,066	65,765	46,685
Transaction costs	535	8	978	2,112
Depreciation and amortization expense	134,604	111,168	255,199	219,630
Interest expense	103,140	99,901	203,573	203,138
Impairment loss	0	0	8,306	0
Impairment loss from discontinued operations	0	0	3,241	0
Noncontrolling interest in property partnerships	(219)	457	2,355	1,003
Noncontrolling interest-redeemable preferred units of the Operating Partnership	1,123	765	2,303	1,566
Noncontrolling interest-common units of the Operating Partnership	50,734	10,318	55,277	16,310
Noncontrolling interest in discontinued operations-common units of the Operating Partnership	88	4,075	1,900	4,159
Net income attributable to Boston Properties, Inc.	455,035	118,559	502,857	166,971
Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Operating Income	320,291	293,997	614,905	567,604
Development and management services income	7,857	9,564	16,593	17,709
Income from unconsolidated joint ventures	48,783	21,191	57,504	32,912
Gain on consolidation of joint ventures	387,801	0	387,801	0
Interest and other income	1,296	2,382	2,767	4,028
Gains (losses) from investments in securities	181	(186)	916	615
Gains from early extinguishments of debt	152	274	152	1,041
Income from discontinued operations	873	218	934	788
Gain on sale of real estate from discontinued operations	0	36,877	0	36,877
Gain on forgiveness of debt from discontinued operations	0	0	20,182	0
General and administrative expense	22,194	19,066	65,765	46,685
Transaction costs	535	8	978	2,112
Depreciation and amortization expense	134,604	111,168	255,199	219,630
Interest expense	103,140	99,901	203,573	203,138
Impairment loss	0	0	8,306	0
Impairment loss from discontinued operations	0	0	3,241	0
Noncontrolling interest in property partnerships	(219)	457	2,355	1,003
Noncontrolling interest-redeemable preferred units of the Operating Partnership	1,123	765	2,303	1,566
Noncontrolling interest-common units of the Operating Partnership	50,734	10,318	55,277	16,310
Noncontrolling interest in discontinued operations-common units of the Operating Partnership	88	4,075	1,900	4,159
Net income attributable to Boston Properties, Inc.	$ 455,035	$ 118,559	$ 502,857	$ 166,971

Subsequent Events subsequent Events (Details) $ / shares in Units, $ in Millions	Jul. 26, 2013 USD ($) mo	Jul. 19, 2013 USD ($)	Aug. 07, 2013 $ / shares shares	Jul. 15, 2013 USD ($) ft²	Jul. 01, 2013 ft²	Jun. 30, 2013 $ / shares
8th Avenue and 46th Street [Member]
Subsequent Event [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Imputed Sales Price		$ 45.0
Equity Method Investment, Net Sales Proceeds		$ 21.8
Cambridge Center Connector [Member]
Subsequent Event [Line Items]
Net Rentable Area \| ft²					43,000
1301 New York Avenue [Member]
Subsequent Event [Line Items]
Contractual Sales Price				$ 135.0
Net Rentable Area \| ft²				201,000
Net Contractual Sales Price				$ 121.7
Minimum [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.125%
Maximum [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.35%
Prior to Amendment [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 750.0
Line of Credit Facility, Expiration Date	Jun. 24, 2014
After Amendment [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,000.0
Line of Credit Facility, Expiration Date	Jul. 26, 2018
After Amendment [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,500.0
Interest Rate Based on LIBOR or CDOR [Member] \| Minimum [Member]
Subsequent Event [Line Items]
Margin added to Calculated Interest Rate	0.925%
Interest Rate Based on LIBOR or CDOR [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Margin added to Calculated Interest Rate	1.70%
Alternative Base Interest Rate Calculation [Member]
Subsequent Event [Line Items]
Amount added to Federal Funds Rate to Calculate Interest Rate	0.50%
LIBOR Period Used to Calculate Interest Rate (in months) \| mo	1
Amount added to LIBOR to Calculate Interest Rate	1.00%
Alternative Base Interest Rate Calculation [Member] \| Minimum [Member]
Subsequent Event [Line Items]
Margin added to Calculated Interest Rate	0.00%
Alternative Base Interest Rate Calculation [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Margin added to Calculated Interest Rate	0.70%
Rate Based on Current Credit Rating [Member] \| Interest Rate Based on LIBOR or CDOR [Member]
Subsequent Event [Line Items]
Margin added to Calculated Interest Rate	1.00%
Rate Based on Current Credit Rating [Member] \| Alternative Base Interest Rate Calculation [Member]
Subsequent Event [Line Items]
Margin added to Calculated Interest Rate	0.00%
Rate Based on Current Credit Rating [Member] \| Current Rates Based on Credit Ratings [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.15%
series four preferred units [Member]
Subsequent Event [Line Items]
Series Four Preferred Units Redeemed \| shares			861,400
Preferred Units Liquidation Preference \| $ / shares			$ 50.00			$ 50.00

Label	Element	Value
Dividends	us-gaap_Dividends	$ 185,155,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	us-gaap_AdjustmentsToAdditionalPaidInCapitalEquityComponentOfConvertibleDebt	(43,869,000)
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	0
Noncontrolling Interest [Member]
Dividends	us-gaap_Dividends	20,100,000
Common Stock [Member]
Net Activity From Stock Option And Incentive Plan Value	bxp_NetActivityFromStockOptionAndIncentivePlanValue	$ 0