Boston Properties (BXP) 10-K 29 Feb 16 2015 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 22, 2016	Jun. 30, 2015
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Entity Registrant Name	BOSTON PROPERTIES INC
Amendment Flag	false
Entity Central Index Key	1,037,540
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		153,592,481
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 18,453,084,348
Boston Properties Limited Partnership [Member]
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Entity Registrant Name	BOSTON PROPERTIES LTD PARTNERSHIP
Amendment Flag	false
Entity Central Index Key	1,043,121
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	0
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float	$ 0

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
ASSETS
Real estate, at cost	$ 19,481,535	$ 19,236,403
Less: accumulated depreciation	(3,925,894)	(3,547,659)
Total real estate	15,555,641	15,688,744
Cash and cash equivalents	723,718	1,763,079
Cash held in escrows	73,790	487,321
Investments in securities	20,380	19,459
Tenant and other receivables (net of allowance for doubtful accounts of $1,197 and $1,142, respectively)	97,865	46,595
Accrued rental income (net of allowance of $2,775 and $1,499, respectively)	754,883	691,999
Deferred charges, net	732,837	831,744
Prepaid expenses and other assets	185,118	164,432
Investments in unconsolidated joint ventures	235,224	193,394
Total assets	18,379,456	19,886,767
Liabilities:
Mortgage notes payable	3,438,714	4,309,484
Unsecured senior notes (net of discount of $10,683 and $12,296, respectively)	5,289,317	5,287,704
Unsecured line of credit	0	0
Mezzanine notes payable	308,482	309,796
Outside members’ notes payable	180,000	180,000
Accounts payable and accrued expenses	274,709	243,263
Dividends and distributions payable	327,320	882,472
Accrued interest payable	190,386	163,532
Other liabilities	483,601	502,255
Total liabilities	10,492,529	11,878,506
Commitments and contingencies	0	0
Noncontrolling interest:
Redeemable preferred units	0	633
Redeemable interest in property partnership	0	104,692
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 / units, liquidation preference $2,500 per share / unit, 80,000 shares / units issued and outstanding at December 31, 2015 and December 31, 2014, respectively	200,000	200,000
Common stock, $.01 par value, 250,000,000 shares authorized, 153,658,866 and 153,192,845 issued and 153,579,966 and 153,113,945 outstanding at December 31, 2015 and December 31, 2014, respectively	1,536	1,531
Additional paid-in capital	6,305,687	6,270,257
Dividends in excess of earnings	(780,952)	(762,464)
Treasury common stock at cost, 78,900 shares at December 31, 2015 and December 31, 2014	(2,722)	(2,722)
Accumulated other comprehensive loss	(14,114)	(9,304)
Total stockholders' equity attributable to Boston Properties, Inc.	5,709,435	5,697,298
Noncontrolling interests:
Common units of the Operating Partnership	603,092	603,171
Property partnerships	1,574,400	1,602,467
Total equity / capital	7,886,927	7,902,936
Total liabilities and equity / capital	18,379,456	19,886,767
Boston Properties Limited Partnership [Member]
ASSETS
Real estate, at cost	19,061,141	18,814,558
Less: accumulated depreciation	(3,846,816)	(3,476,321)
Total real estate	15,214,325	15,338,237
Cash and cash equivalents	723,718	1,763,079
Cash held in escrows	73,790	487,321
Investments in securities	20,380	19,459
Tenant and other receivables (net of allowance for doubtful accounts of $1,197 and $1,142, respectively)	97,865	46,595
Accrued rental income (net of allowance of $2,775 and $1,499, respectively)	754,883	691,999
Deferred charges, net	732,837	831,744
Prepaid expenses and other assets	185,118	164,432
Investments in unconsolidated joint ventures	235,224	193,394
Total assets	18,038,140	19,536,260
Liabilities:
Mortgage notes payable	3,438,714	4,309,484
Unsecured senior notes (net of discount of $10,683 and $12,296, respectively)	5,289,317	5,287,704
Unsecured line of credit	0	0
Mezzanine notes payable	308,482	309,796
Outside members’ notes payable	180,000	180,000
Accounts payable and accrued expenses	274,709	243,263
Dividends and distributions payable	327,320	882,472
Accrued interest payable	190,386	163,532
Other liabilities	483,601	502,255
Total liabilities	10,492,529	11,878,506
Noncontrolling interest:
Redeemable interest in property partnership	0	104,692
Redeemable partnership units—0 and 12,667 series four preferred units outstanding at redemption value at December 31, 2015 and December 31, 2014, respectively	0	633
Redeemable partnership units—16,097,473 and 16,453,670 common units and 1,831,714 and 1,496,799 long term incentive units outstanding at redemption value at December 31, 2015 and December 31, 2014, respectively	2,286,689	2,310,046
Preferred stock, $.01 par value, 50,000,000 shares authorized;
5.25% Series B cumulative redeemable preferred stock / units, liquidation preference $2,500 per share / unit, 80,000 shares / units issued and outstanding at December 31, 2015 and December 31, 2014, respectively	193,623	193,623
Boston Properties Limited Partnership partners’ capital—1,715,092 and 1,710,644 general partner units and 151,864,874 and 151,403,301 limited partner units outstanding at December 31, 2015 and December 31, 2014, respectively	3,490,899	3,446,293
Accumulated other comprehensive loss	(18,337)	(12,973)
Noncontrolling interests:
Property partnerships	1,574,400	1,602,467
Total equity / capital	5,258,922	5,242,383
Total liabilities and equity / capital	$ 18,038,140	$ 19,536,260

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Tenant and other receivables, allowance for doubtful accounts	$ 1,197	$ 1,142
Accrued rental income, allowance	2,775	1,499
Unsecured senior notes, discount	$ 10,683	12,296
General Partners' Capital Account, Units Outstanding (in units)	1,715,092
Limited Partners' Capital Account, Units Outstanding (in units)	151,864,874
Unsecured exchangeable senior notes, discount	$ 0	$ 0
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	153,658,866	153,192,845
Common stock, shares outstanding	153,579,966	153,113,945
Treasury common stock at cost, shares	78,900	78,900
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Preferred stock, par value	$ 0.01	$ 0
Preferred stock, shares authorized	92,000	92,000
Series B Dividend Rate Percentage	5.25%	5.25%
Preferred stock / units, shares / units issued (in shares / units)	80,000	80,000
Series B Liquidation Preference Per Share/ Unit	$ 2,500	$ 2,500
Preferred stock / units, shares / units outstanding (in shares / units)	80,000	80,000
Boston Properties Limited Partnership [Member]
Tenant and other receivables, allowance for doubtful accounts	$ 1,197	$ 1,142
Accrued rental income, allowance	2,775	1,499
Unsecured senior notes, discount	$ 10,683	$ 12,296
Redeemable Partnership Units Series Four Preferred Units Shares Outstanding ( in units)	0	12,667
Redeemable Partnership Units Common Units Shares Outstanding (in units)	16,097,473	16,453,670
Redeemable Partnership Units Common Units Long Term Incentive Units At Redemption Value Units Outstanding (in units)	1,831,714	1,496,799
General Partners' Capital Account, Units Outstanding (in units)	1,715,092	1,710,644
Limited Partners' Capital Account, Units Outstanding (in units)	151,864,874	151,403,301

Consolidated Statements Of Oper

Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue
Base rent	$ 1,964,732	$ 1,886,339	$ 1,675,412
Recoveries from tenants	355,508	339,365	292,944
Parking and other	101,981	102,593	97,158
Total rental revenue	2,422,221	2,328,297	2,065,514
Hotel revenue	46,046	43,385	40,330
Development and management services	22,554	25,316	29,695
Total revenue	2,490,821	2,396,998	2,135,539
Expenses
Rental	872,252	835,290	742,956
Hotel	32,084	29,236	28,447
General and administrative	96,319	98,937	115,329
Transaction costs	1,259	3,140	1,744
Impairment loss	0	0	8,306
Depreciation and amortization	639,542	628,573	560,637
Total expenses	1,641,456	1,595,176	1,457,419
Operating income	849,365	801,822	678,120
Other income (expense)
Income from unconsolidated joint ventures	22,770	12,769	75,074
Gains on consolidation of joint ventures	0	0	385,991
Interest and other income	6,777	8,765	8,310
Gains (losses) from investments in securities	(653)	1,038	2,911
Interest expense	(432,196)	(455,743)	(446,880)
(Losses) gains from early extinguishments of debt	(22,040)	(10,633)	122
Income (loss) from continuing operations	424,023	358,018	703,648
Discontinued operations
Income from discontinued operations	0	0	8,022
Gain on sale of real estate from discontinued operations	0	0	112,829
Gain on forgiveness of debt from discontinued operations	0	0	20,182
Impairment loss from discontinued operations	0	0	(3,241)
Income before gains on sales of real estate	424,023	358,018	841,440
Gains on sales of real estate	375,895	168,039	0
Net income (loss)	799,918	526,057	841,440
Net income attributable to noncontrolling interests
Noncontrolling interests in property partnerships	(149,855)	(30,561)	(1,347)
Noncontrolling interest - redeemable preferred units	(6)	(1,023)	(6,046)
Noncontrolling interest - common units of the Operating Partnership	(66,951)	(50,862)	(70,085)
Noncontrolling interest in discontinued operations - common units of the Operating Partnership	0	0	(14,151)
Net income attributable to the Company	583,106	443,611	749,811
Preferred dividends / distributions	(10,500)	(10,500)	(8,057)
Net income attributable to the Company''s common shareholders / unitholders	$ 572,606	$ 433,111	$ 741,754
Basic earnings per common share / unit attributable to the Company
Income from continuing operations (in dollars per share / unit)	$ 3.73	$ 2.83	$ 4.06
Discontinued operations (in dollars per share / unit)	0	0	0.81
Net income (in dollars per share / unit)	$ 3.73	$ 2.83	$ 4.87
Weighted average number of common shares / units outstanding (in shares / units)	153,471	153,089	152,201
Diluted earnings per common share / unit attributable to the Company
Income from continuing operations (in dollars per share / unit)	$ 3.72	$ 2.83	$ 4.05
Discontinued operations (in dollars per share / unit)	0	0	0.81
Diluted Earnings: Net income, Per Share / Unit Amount (in dollars per share / unit)	$ 3.72	$ 2.83	$ 4.86
Weighted average number of common and common equivalent shares / units outstanding (in shares / units)	153,844	153,308	152,521
Boston Properties Limited Partnership [Member]
Revenue
Base rent	$ 1,964,732	$ 1,886,339	$ 1,675,412
Recoveries from tenants	355,508	339,365	292,944
Parking and other	101,981	102,593	97,158
Total rental revenue	2,422,221	2,328,297	2,065,514
Hotel revenue	46,046	43,385	40,330
Development and management services	22,554	25,316	29,695
Total revenue	2,490,821	2,396,998	2,135,539
Expenses
Rental	872,252	835,290	742,956
Hotel	32,084	29,236	28,447
General and administrative	96,319	98,937	115,329
Transaction costs	1,259	3,140	1,744
Impairment loss	0	0	4,401
Depreciation and amortization	631,549	620,064	552,589
Total expenses	1,633,463	1,586,667	1,445,466
Operating income	857,358	810,331	690,073
Other income (expense)
Income from unconsolidated joint ventures	22,770	12,769	75,074
Gains on consolidation of joint ventures	0	0	385,991
Interest and other income	6,777	8,765	8,310
Gains (losses) from investments in securities	(653)	1,038	2,911
Interest expense	(432,196)	(455,743)	(446,880)
(Losses) gains from early extinguishments of debt	(22,040)	(10,633)	122
Income (loss) from continuing operations	432,016	366,527	715,601
Discontinued operations
Income from discontinued operations	0	0	8,022
Gain on sale of real estate from discontinued operations	0	0	115,459
Gain on forgiveness of debt from discontinued operations	0	0	20,736
Impairment loss from discontinued operations	0	0	(2,852)
Income before gains on sales of real estate	432,016	366,527	856,966
Gains on sales of real estate	377,093	174,686	0
Net income (loss)	809,109	541,213	856,966
Net income attributable to noncontrolling interests
Noncontrolling interests in property partnerships	(149,855)	(30,561)	(1,347)
Noncontrolling interest - redeemable preferred units	(6)	(1,023)	(6,046)
Net income attributable to the Company	659,248	509,629	849,573
Preferred dividends / distributions	(10,500)	(10,500)	(8,057)
Net income attributable to the Company''s common shareholders / unitholders	$ 648,748	$ 499,129	$ 841,516
Basic earnings per common share / unit attributable to the Company
Income from continuing operations (in dollars per share / unit)	$ 3.79	$ 2.93	$ 4.14
Discontinued operations (in dollars per share / unit)	0	0	0.83
Net income (in dollars per share / unit)	$ 3.79	$ 2.93	$ 4.97
Weighted average number of common shares / units outstanding (in shares / units)	171,139	170,453	169,126
Diluted earnings per common share / unit attributable to the Company
Income from continuing operations (in dollars per share / unit)	$ 3.78	$ 2.92	$ 4.14
Discontinued operations (in dollars per share / unit)	0	0	0.83
Diluted Earnings: Net income, Per Share / Unit Amount (in dollars per share / unit)	$ 3.78	$ 2.92	$ 4.97
Weighted average number of common and common equivalent shares / units outstanding (in shares / units)	171,512	170,672	169,446

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net income		$ 799,918	$ 526,057	$ 841,440
Other comprehensive income (loss):
Effective portion of interest rate contracts		(10,302)	0	0
Amortization of interest rate contracts	[1],[2]	2,510	2,508	2,513
Other comprehensive income (loss)		(7,792)	2,508	2,513
Comprehensive Income		792,126	528,565	843,953
Comprehensive income attributable to noncontrolling interests		(216,812)	(82,446)	(91,629)
Other comprehensive income (loss) attributable to noncontrolling interests		2,982	(256)	(252)
Comprehensive income attributable to the Company		578,296	445,863	752,072
Boston Properties Limited Partnership [Member]
Net income		809,109	541,213	856,966
Other comprehensive income (loss):
Effective portion of interest rate contracts		(10,302)	0	0
Amortization of interest rate contracts	[2],[3]	2,510	2,508	2,513
Other comprehensive income (loss)		(7,792)	2,508	2,513
Comprehensive Income		801,317	543,721	859,479
Comprehensive income attributable to noncontrolling interests		(147,433)	(31,584)	(7,393)
Comprehensive income attributable to the Company		$ 653,884	$ 512,137	$ 852,086
[1]	Amounts reclassified from comprehensive income primarily to interest expense within Boston Properties, Inc.’s Consolidated Statements of Operations
[2]	Consists of amounts from interest rate hedging programs entered into prior to 2015.
[3]	Amounts reclassified from comprehensive income primarily to interest expense within Boston Properties Limited Partnership's Consolidated Statements of Operations.

Consolidated Statements Of Stoc

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, 2012	$ 5,634,854	$ 1,516		$ 5,222,073	$ (109,985)	$ (2,722)	$ (13,817)	$ 537,789
Equity, shares at Dec. 31, 2012		151,601,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units to Common Stock, shares		929,000
Conversion of operating partnership units to Common Stock, value	0	$ 10		30,281				(30,291)
Conversion of redeemable preferred units to common units	16,494							16,494
Allocated net income for the year	828,757				749,811			78,946
Dividends/distributions declared	(831,826)				(748,378)			(83,448)
Issuance of 5.25% Series B cumulative redeemable preferred stock	193,623		$ 200,000	(6,377)
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)			(43,869)
shares issued in connection with exchange of exchangeable senior notes, shares		419,000
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan		6,000
Shares issued pursuant to stock purchase plan, value	681			681
Net activity from stock option and incentive plan, shares		28,000
Net activity from stock option and incentive plan, value	35,571			7,701				27,870
Noncontrolling interest in property partnerships recorded upon consolidation	480,861							480,861
Sale of interest in property partnerships and contributions from noncontrolling interest in property partnerships	687,164			429,600				257,564
Distributions to noncontrolling interests in property partnerships	(5,039)							(5,039)
Amortization of interest rate contracts	2,513						2,261	252
Conversion of redeemable partnership units	0			(21,467)				21,467
Equity, value at Dec. 31, 2013	7,043,618	$ 1,530	200,000	5,662,453	(108,552)	(2,722)	(11,556)	1,302,465
Equity, shares at Dec. 31, 2013		152,983,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units to Common Stock, shares		80,000
Conversion of operating partnership units to Common Stock, value	0	$ 1		2,699				(2,700)
Conversion of redeemable preferred units to common units	33,306							33,306
Allocated net income for the year	513,951				443,611			70,340
Dividends/distributions declared	(1,224,471)				(1,097,523)			(126,948)
Shares issued in connection with exchange of exchangeable senior notes, value	0
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan		7,000
Shares issued pursuant to stock purchase plan, value	761			761
Net activity from stock option and incentive plan, shares		44,000
Net activity from stock option and incentive plan, value	27,999			6,822				21,177
Noncontrolling interest in property partnerships recorded upon consolidation	0
Sale of interest in property partnerships and contributions from noncontrolling interest in property partnerships	1,536,382			648,407				887,975
Distributions to noncontrolling interests in property partnerships	(31,118)							(31,118)
Amortization of interest rate contracts	2,508						2,252	256
Conversion of redeemable partnership units	0			(50,885)				50,885
Equity, value at Dec. 31, 2014	$ 7,902,936	$ 1,531	200,000	6,270,257	(762,464)	(2,722)	(9,304)	2,205,638
Equity, shares at Dec. 31, 2014	153,113,945	153,114,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units to Common Stock, shares		424,000
Conversion of operating partnership units to Common Stock, value	$ 0	$ 5		14,338				(14,343)
Allocated net income for the year	794,791				583,106			211,685
Dividends/distributions declared	(671,041)				(601,594)			(69,447)
Shares issued in connection with exchange of exchangeable senior notes, value	0
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan		6,000
Shares issued pursuant to stock purchase plan, value	780			780
Net activity from stock option and incentive plan, shares		36,000
Net activity from stock option and incentive plan, value	40,265			5,814				34,451
Acquisition of redeemable noncontrolling interest in property partnership	(1,586)			(1,586)
Sale of an interest in property partnerships	0			(1,053)				1,053
Proceeds from Noncontrolling Interests	2,705							2,705
Noncontrolling interest in property partnerships recorded upon consolidation	0
Distributions to noncontrolling interests in property partnerships	(170,049)							(170,049)
Dissolution of a property partnership	(4,082)							(4,082)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	(10,302)						(7,061)	(3,241)
Amortization of interest rate contracts	2,510						2,251	259
Conversion of redeemable partnership units	0			17,137				(17,137)
Equity, value at Dec. 31, 2015	$ 7,886,927	$ 1,536	$ 200,000	$ 6,305,687	$ (780,952)	$ (2,722)	$ (14,114)	$ 2,177,492
Equity, shares at Dec. 31, 2015	153,579,966	153,580,000

Consolidated Statement of Partn

Consolidated Statement of Partners' Capital Statement - USD ($) $ in Thousands	Total	Boston Properties Limited Partnership [Member]
Beginning balance at Dec. 31, 2012		$ 3,330,605
Increase (Decrease) in Partners' Capital [Roll Forward]
Contributions		626,568
Net income allocable to general and limited partner units		765,337
Distributions		(748,378)
Other comprehensive Income (loss)		2,261
Unearned compensation		5,002
Conversion of redeemable partnership units		30,291
Adjustment to reflect redeemable partnership units at redemption value		175,485
Ending Balance at Dec. 31, 2013		4,187,171
Increase (Decrease) in Partners' Capital [Roll Forward]
Contributions		652,692
Net income allocable to general and limited partner units		458,767
Distributions		(1,097,523)
Other comprehensive Income (loss)		2,252
Unearned compensation		3,298
Conversion of redeemable partnership units		2,700
Adjustment to reflect redeemable partnership units at redemption value		(569,441)
Ending Balance at Dec. 31, 2014		3,639,916
Increase (Decrease) in Partners' Capital [Roll Forward]
Contributions		4,071
Acquisition of redeemable noncontrolling interest in property partnership	$ (1,586)	(1,586)
Net income allocable to general and limited partner units		592,297
Distributions		(601,594)
Other comprehensive Income (loss)		(4,810)
Unearned compensation		1,470
Conversion of redeemable partnership units		14,343
Adjustment to reflect redeemable partnership units at redemption value		40,415
Ending Balance at Dec. 31, 2015		$ 3,684,522

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net income	$ 799,918	$ 526,057	$ 841,440
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	639,542	628,573	565,397
Non-cash compensation expense	29,183	28,099	45,155
Impairment loss	0	0	8,306
Income from unconsolidated joint ventures	(22,770)	(12,769)	(75,074)
Gains on consolidation of joint ventures	0	0	(385,991)
Distributions of net cash flow from operations of unconsolidated joint ventures	8,469	7,372	32,600
Losses (gains) on investments in securities	653	(1,038)	(2,911)
Non-cash portion of interest expense	(42,271)	(39,343)	2,649
Settlement of accreted debt discount on repurchases/repayments of unsecured senior notes and unsecured exchangeable senior notes	0	(94,963)	(56,532)
Losses (gains) from early extinguishments of debt	21,837	0	(264)
Gains on sales of real estate	(375,895)	(168,039)	0
Gain on sale of real estate from discontinued operations	0	0	(112,829)
Gain on forgiveness of debt from discontinued operations	0	0	(20,182)
Impairment loss from discontinued operations	0	0	3,241
Change in assets and liabilities:
Cash held in escrows	(18,284)	3,433	315
Tenant and other receivables, net	(46,326)	12,869	(443)
Accrued rental income, net	(73,911)	(57,899)	(59,972)
Prepaid expenses and other assets	(16,877)	20,238	12,966
Accounts payable and accrued expenses	(6,310)	3,903	13,108
Accrued interest payable	26,854	(3,991)	21,302
Other liabilities	(34,005)	(57,873)	2,073
Tenant leasing costs	(90,396)	(99,076)	(56,428)
Total adjustments	(507)	169,496	(63,514)
Net cash provided by operating activities	799,411	695,553	777,926
Cash flows from investing activities:
Acquisitions of real estate	0	(4,670)	(522,900)
Construction in progress	(374,664)	(405,942)	(396,835)
Building and other capital improvements	(112,755)	(82,479)	(73,821)
Tenant improvements	(144,572)	(106,003)	(105,425)
Proceeds from sales of real estate	602,600	419,864	250,078
Proceeds from sales of real estate and sales of interests in property partnerships placed in escrow	(200,612)	(1,912,347)	0
Proceeds from sales of real estate and sales of interests in property partnerships released from escrow	634,165	1,478,794	0
Cash placed in escrow for land sale contracts	(7,111)	0	0
Cash released from scrow for land sale contracts	5,312	0	0
Cash recorded upon consolidation		0	79,468
Issuance of notes receivable,net	0	0	12,491
Capital contributions to unconsolidated joint ventures	(38,207)	(52,052)	0
Capital distributions from unconsolidated joint ventures	24,527	1,491	225,862
Investments in marketable securities	(667,335)	0	0
Investments in securities, net	(1,574)	(1,780)	(1,558)
Net cash used in investing activities	(280,226)	(665,124)	(532,640)
Cash flows from financing activities:
Repayments of mortgage notes payable	(54,801)	(87,758)	(80,311)
Proceeds from unsecured senior notes	0	0	1,194,753
Redemption/repurchase of unsecured senior notes	0	(548,016)	0
Redemption/repurchase/exchange of unsecured exchangeable senior notes	0	(654,521)	(393,468)
Payments on capital lease obligation	(356)	0	0
Proceeds from real estate financing transaction	6,000	14,523	0
Payments on real estate financing transactions	(3,103)	(234)	0
Deferred financing costs	(1,510)	(31)	(15,195)
Net proceeds from preferred stock / unit issuance	0	0	193,623
Net proceeds from equity transactions	799	1,923	(334)
Redemption of preferred units	(633)	(17,373)	(43,070)
Dividends and distributions	(1,226,199)	(840,264)	(451,118)
Sales of interests in property partnerships and contributions from noncontrolling interests in property partnerships	2,705	1,536,382	682,617
Acquisition of noncontrolling interest in property partnership	(108,499)	0	0
Distributions to noncontrolling interest in property partnerships	(172,949)	(37,118)	(9,624)
Net cash provided by (used in) financing activities	(1,558,546)	(632,487)	1,077,873
Net increase (decrease) in cash and cash equivalents	(1,039,361)	(602,058)	1,323,159
Cash and cash equivalents, beginning of year	1,763,079	2,365,137	1,041,978
Cash and cash equivalents, end of year	723,718	1,763,079	2,365,137
Supplemental disclosures:
Cash paid for interest	481,826	646,516	547,973
Interest capitalized	34,213	52,476	68,152
Non-cash investing and financing activities:
Change in real estate included in accounts payable and accrued expenses	74,985	(1,431)	(19,824)
Real estate and related intangibles recorded upon consolidation	0	0	3,356,000
Debt recorded upon consolidation	0	0	2,056,000
Working capital recorded upon consolidation	0	0	177,315
Noncontrolling Interests recorded upon consolidation	0	0	480,861
investment in unconsolidated joint venture elminated upon consolidation	0	0	361,808
Mortgage note extinguished through foreclosure	0	0	25,000
Real estate transferred upon foreclosure	0	0	7,508
Land improvements contributed by noncontrolling interests in property partnership	0	0	4,546
Marketable securities transferred in connection with the legal defeasance of mortgage note payable	667,335	0	0
Mortgage note payable legally defeased	640,500	0	0
Mortgage note payable assigned in connection with the sale of real estate	116,993	0	0
Dividends and distributions declared but not paid	327,320	882,472	497,242
Issuance of common stock in connection with the exchange of exchangeable senior notes	0	0	43,834
Conversions of redeemable partnership units to partners’ capital / stockholders equity	14,343	2,700	30,291
Conversion of redeemable preferred units to common units	0	33,306	16,494
Issuance of restricted securities to employees and directors	43,355	27,445	30,077
Boston Properties Limited Partnership [Member]
Net income	809,109	541,213	856,966
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	631,549	620,064	557,349
Non-cash compensation expense	29,183	28,099	45,155
Impairment loss	0	0	4,401
Income from unconsolidated joint ventures	(22,770)	(12,769)	(75,074)
Gains on consolidation of joint ventures	0	0	(385,991)
Distributions of net cash flow from operations of unconsolidated joint ventures	8,469	7,372	32,600
Losses (gains) on investments in securities	653	(1,038)	(2,911)
Non-cash portion of interest expense	(42,271)	(39,343)	2,649
Settlement of accreted debt discount on repurchases/repayments of unsecured senior notes and unsecured exchangeable senior notes	0	(94,963)	(56,532)
Losses (gains) from early extinguishments of debt	21,837	0	(264)
Gains on sales of real estate	(377,093)	(174,686)	0
Gain on sale of real estate from discontinued operations	0	0	(115,459)
Gain on forgiveness of debt from discontinued operations	0	0	(20,736)
Impairment loss from discontinued operations	0	0	2,852
Change in assets and liabilities:
Cash held in escrows	(18,284)	3,433	315
Tenant and other receivables, net	(46,326)	12,869	(443)
Accrued rental income, net	(73,911)	(57,899)	(59,972)
Prepaid expenses and other assets	(16,877)	20,238	12,966
Accounts payable and accrued expenses	(6,310)	3,903	13,108
Accrued interest payable	26,854	(3,991)	21,302
Other liabilities	(34,005)	(57,873)	2,073
Tenant leasing costs	(90,396)	(99,076)	(56,428)
Total adjustments	(9,698)	154,340	(79,040)
Net cash provided by operating activities	799,411	695,553	777,926
Cash flows from investing activities:
Acquisitions of real estate	0	(4,670)	(522,900)
Construction in progress	(374,664)	(405,942)	(396,835)
Building and other capital improvements	(112,755)	(82,479)	(73,821)
Tenant improvements	(144,572)	(106,003)	(105,425)
Proceeds from sales of real estate	602,600	419,864	250,078
Proceeds from sales of real estate and sales of interests in property partnerships placed in escrow	(200,612)	(1,912,347)	0
Proceeds from sales of real estate and sales of interests in property partnerships released from escrow	634,165	1,478,794	0
Cash placed in escrow for land sale contracts	(7,111)	0	0
Cash released from scrow for land sale contracts	5,312	0	0
Cash recorded upon consolidation	0	0	79,468
Issuance of notes receivable,net	0	0	12,491
Capital contributions to unconsolidated joint ventures	(38,207)	(52,052)	0
Capital distributions from unconsolidated joint ventures	24,527	1,491	225,862
Investments in marketable securities	(667,335)	0	0
Investments in securities, net	(1,574)	(1,780)	(1,558)
Net cash used in investing activities	(280,226)	(665,124)	(532,640)
Cash flows from financing activities:
Repayments of mortgage notes payable	(54,801)	(87,758)	(80,311)
Proceeds from unsecured senior notes	0	0	1,194,753
Redemption/repurchase of unsecured senior notes	0	(548,016)	0
Redemption/repurchase/exchange of unsecured exchangeable senior notes	0	(654,521)	(393,468)
Payments on capital lease obligation	(356)	0	0
Proceeds from real estate financing transaction	6,000	14,523	0
Payments on real estate financing transactions	(3,103)	(234)	0
Deferred financing costs	(1,510)	(31)	(15,195)
Net proceeds from preferred stock / unit issuance	0	0	193,623
Net proceeds from equity transactions	799	1,923	(334)
Redemption of preferred units	(633)	(17,373)	(43,070)
Dividends and distributions	(1,226,199)	(840,264)	(451,118)
Sales of interests in property partnerships and contributions from noncontrolling interests in property partnerships	2,705	1,536,382	682,617
Acquisition of noncontrolling interest in property partnership	(108,499)	0	0
Distributions to noncontrolling interest in property partnerships	(172,949)	(37,118)	(9,624)
Net cash provided by (used in) financing activities	(1,558,546)	(632,487)	1,077,873
Net increase (decrease) in cash and cash equivalents	(1,039,361)	(602,058)	1,323,159
Cash and cash equivalents, beginning of year	1,763,079	2,365,137	1,041,978
Cash and cash equivalents, end of year	723,718	1,763,079	2,365,137
Supplemental disclosures:
Cash paid for interest	481,826	646,516	547,973
Interest capitalized	34,213	52,476	68,152
Non-cash investing and financing activities:
Change in real estate included in accounts payable and accrued expenses	74,985	(1,431)	(19,824)
Real estate and related intangibles recorded upon consolidation	0	0	3,356,000
Debt recorded upon consolidation	0	0	2,056,000
Working capital recorded upon consolidation	0	0	177,315
Noncontrolling Interests recorded upon consolidation	0	0	480,861
investment in unconsolidated joint venture elminated upon consolidation	0	0	361,808
Mortgage note extinguished through foreclosure	0	0	25,000
Real estate transferred upon foreclosure	0	0	7,508
Land improvements contributed by noncontrolling interests in property partnership	0	0	4,546
Marketable securities transferred in connection with the legal defeasance of mortgage note payable	667,335	0	0
Mortgage note payable legally defeased	640,500	0	0
Mortgage note payable assigned in connection with the sale of real estate	116,993	0	0
Dividends and distributions declared but not paid	327,320	882,472	497,242
Issuance of common stock in connection with the exchange of exchangeable senior notes	0	0	43,834
Conversions of redeemable partnership units to partners’ capital / stockholders equity	14,343	2,700	30,291
Conversion of redeemable preferred units to common units	0	33,306	16,494
Issuance of restricted securities to employees and directors	$ 43,355	$ 27,445	$ 30,077

Organization

Organization	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Boston Properties, Inc., a Delaware corporation, is a fully integrated, self-administered and self-managed real estate investment trust (“REIT”). Boston Properties, Inc. is the sole general partner of Boston Properties Limited Partnership and at December 31, 2015 owned an approximate 89.5% ( 89.5% at December 31, 2014 ) general and limited partnership interest in Boston Properties Limited Partnership. Unless stated otherwise or the context requires, the “Company” refers to Boston Properties, Inc. and its subsidiaries, including Boston Properties Limited Partnership, its operating partnership, and its consolidated subsidiaries. Partnership interests in Boston Properties Limited 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 2012, Boston Properties Limited Partnership issued LTIP Units in connection with the granting to employees of outperformance awards (also referred to as “2012 OPP Units”). On February 6, 2015, the measurement period for Boston Properties Limited Partnership’s 2012 OPP Unit awards expired and Boston Properties, Inc.’s total stockholder return (“TSR”) was sufficient for employees to earn and therefore become eligible to vest in a portion of the 2012 OPP Unit awards (See Note 17 ). In February 2013, February 2014 and February 2015, Boston Properties, Inc. issued LTIP Units in connection with the granting to employees of multi-year, long-term incentive program (“MYLTIP”) awards (also referred to as “2013 MYLTIP Units,” “2014 MYLTIP Units” and “2015 MYLTIP Units,” respectively, and collectively as “MYLTIP Units”). Because the rights, preferences and privileges of MYLTIP Units differ from other LTIP Units granted to employees as part of the annual compensation process (including, as of February 6, 2015, the 2012 OPP Units), unless specifically noted otherwise, all references to LTIP Units exclude MYLTIP Units when and until they are earned (See Notes 11 , 17 and 20 ). Unless specifically noted otherwise, all references to OP Units exclude units held by Boston Properties, Inc. A holder of an OP Unit may present such OP Unit to Boston Properties Limited 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, Boston Properties Limited Partnership is obligated to redeem such OP Unit for cash equal to the value of a share of common stock of Boston Properties, Inc. (“Common Stock”) at such time. In lieu of a cash redemption, Boston Properties, Inc. may elect to acquire such OP Unit for one share of Common Stock. Because the number of shares of Common Stock outstanding at all times equals the number of OP Units that Boston Properties, Inc. owns, one share of Common Stock is generally the economic equivalent of one OP Unit, and the quarterly distribution that may be paid to the holder of an OP Unit equals the quarterly dividend that may be paid to the holder of a share of Common Stock. At the time of an award, LTIP Units do not have full economic parity with OP Units or Common Stock, but can achieve parity over time upon the occurrence of specified events in accordance with partnership tax rules. LTIP Units, whether vested or not, will receive the same quarterly per unit distributions as OP Units, which equal per share dividends on Common Stock (See Note 12 ). At December 31, 2015 , there was one series of Preferred Units outstanding (i.e., Series B Preferred Units). The Series B Preferred Units were issued to Boston Properties, Inc. in connection with its 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”). Boston Properties, Inc. contributed the net proceeds from the offering to Boston Properties Limited 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 12 ). Properties At December 31, 2015 , the Company owned or had interests in a portfolio of 168 commercial real estate properties (the “Properties”) aggregating approximately 46.5 million net rentable square feet, including eleven properties under construction/redevelopment totaling approximately 4.6 million net rentable square feet. At December 31, 2015 , the Properties consist of: • 158 office properties, including 127 Class A office properties (including nine properties under construction/redevelopment) and 31 Office/Technical properties; • one hotel; • five retail properties; and • four residential properties (including two properties under construction) The Company owns or controls undeveloped land parcels totaling approximately 457.1 acres. The Company considers Class A office properties to be centrally located buildings that are professionally managed and maintained, attract high-quality tenants and command upper-tier rental rates, and that are modern structures or have been modernized to compete with newer buildings. The Company considers Office/Technical properties to be properties that support office, research and development, laboratory and other technical uses. The Company’s definitions of Class A Office and Office/Technical properties may be different than those used by other companies. Net rentable square feet amounts are unaudited. Basis of Presentation Boston Properties, Inc. does not have any other significant assets, liabilities or operations, other than its investment in Boston Properties Limited Partnership, nor does it have employees of its own. Boston Properties Limited Partnership, not Boston Properties, Inc., generally executes all significant business relationships other than transactions involving securities of Boston Properties, Inc. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. At December 31, 2015 and 2014, the Company did not have any VIEs. 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.

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis Of Presentation And Summary Of Significant Accounting Policies	2. Summary of Significant Accounting Policies Real Estate Upon acquisitions of real estate that constitutes a business, which includes the consolidation of previously unconsolidated joint ventures, the Company assesses the fair value of acquired tangible and intangible assets (including land, buildings, tenant improvements, “above-” and “below-market” leases, leasing and assumed financing origination costs, acquired in-place leases, other identified intangible assets and assumed liabilities) and allocates the purchase price to the acquired assets and assumed liabilities, including land and buildings as if vacant. The Company assesses and considers fair value based on estimated cash flow projections that utilize discount and/or capitalization rates that it deems appropriate, as well as available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known and anticipated trends, and market and economic conditions. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant. The Company also considers an allocation of purchase price of other acquired intangibles, including acquired in-place leases that may have a customer relationship intangible value, including (but not limited to) the nature and extent of the existing relationship with the tenants, the tenants’ credit quality and expectations of lease renewals. Based on its acquisitions to date, the Company’s allocation to customer relationship intangible assets has been immaterial. The Company records acquired “above-” and “below-market” leases at their fair values (using a discount rate which reflects the risks associated with the leases acquired) equal to the difference between (1) the contractual amounts to be paid pursuant to each in-place lease and (2) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the initial term plus the term of any below-market fixed rate renewal options for below- market leases. Acquired “above-” and “below-market” lease values have been reflected within Prepaid Expenses and Other Assets and Other Liabilities, respectively, in the Company’s Consolidated Balance Sheets. Other intangible assets acquired include amounts for in-place lease values that are based on the Company’s evaluation of the specific characteristics of each tenant’s lease. Factors to be considered include estimates of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, the Company considers leasing commissions, legal and other related expenses. Management reviews its long-lived assets for impairment following the end of each quarter and when there is an event or change in circumstances that indicates an impairment in value. An impairment loss is recognized if the carrying amount of its assets is not recoverable and exceeds its fair value. If such criteria are present, an impairment loss is recognized based on the excess of the carrying amount of the asset over its fair value. The evaluation of anticipated cash flows is highly subjective and is based in part on assumptions regarding future occupancy, rental rates and capital requirements that could differ materially from actual results in future periods. Since cash flows on properties considered to be “long-lived assets to be held and used” are considered on an undiscounted basis to determine whether an asset has been impaired, the Company’s established strategy of holding properties over the long term directly decreases the likelihood of recording an impairment loss. If the Company’s strategy changes or market conditions otherwise dictate an earlier sale date, an impairment loss may be recognized and such loss could be material. If the Company determines that an impairment has occurred, the affected assets must be reduced to their fair value, less cost to sell. Guidance in Accounting Standards Codification (“ASC”) 360 “Property Plant and Equipment” (“ASC 360”) requires that qualifying assets and liabilities and the results of operations that have been sold, or otherwise qualify as “held for sale,” be presented as discontinued operations in all periods presented if the property operations are expected to be eliminated and the Company will not have significant continuing involvement following the sale. The components of the property’s net income that are reflected as discontinued operations include the net gain (or loss) upon the disposition of the property held for sale, operating results, depreciation and interest expense (if the property is subject to a secured loan). The Company generally considers assets to be “held for sale” when the transaction has been approved by Boston Properties, Inc.’s Board of Directors, or a committee thereof, and there are no known significant contingencies relating to the sale, such that a sale of the property within one year is considered probable. Following the classification of a property as “held for sale,” no further depreciation is recorded on the assets, and the asset is written down to the lower of carrying value or fair market value, less cost to sell. On April 10, 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity” (“ASU 2014-08”). ASU 2014-08 clarifies that discontinued operations presentation applies only to disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results (e.g., a disposal of a major geographical area, a major line of business, a major equity method investment or other major parts of an entity). ASU 2014-08 is effective prospectively for reporting periods beginning after December 15, 2014. Early adoption is permitted, and the Company early adopted ASU 2014-08 during the first quarter of 2014. The Company’s adoption of ASU 2014-08 resulted in the operating results and gains on sales of real estate from operating properties sold during the years ended December 31, 2015 and 2014 not being reflected within Discontinued Operations in the Company’s Consolidated Statements of Operations (See Note 3 ). Real estate is stated at depreciated cost. A variety of costs are incurred in the acquisition, development and leasing of properties. The cost of buildings and improvements includes the purchase price of property, legal fees and other acquisition costs. The Company expenses costs that it incurs to effect a business combination such as legal, due diligence and other closing related costs. Costs directly related to the development of properties are capitalized. Capitalized development costs include interest, internal wages, property taxes, insurance, and other project costs incurred during the period of development. After the determination is made to capitalize a cost, it is allocated to the specific component of a project that is benefited. Determination of when a development project commences and capitalization begins, and when a development project is substantially complete and held available for occupancy and capitalization must cease, involves a degree of judgment. The Company’s capitalization policy on development properties is guided by guidance in ASC 835-20 “Capitalization of Interest” and ASC 970 “Real Estate-General.” The costs of land and buildings under development include specifically identifiable costs. The capitalized costs include pre-construction costs necessary to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. The Company begins the capitalization of costs during the pre-construction period which it defines as activities that are necessary to the development of the property. The Company considers a construction project as substantially completed and held available for occupancy upon the completion of tenant improvements, but no later than one year from cessation of major construction activity. The Company ceases capitalization on the portion (1) substantially completed, (2) occupied or held available for occupancy, and capitalizes only those costs associated with the portion under construction or (3) if activities necessary for the development of the property have been suspended. Interest costs capitalized for the years ended December 31, 2015 , 2014 and 2013 were $34.2 million , $52.5 million and $68.2 million , respectively. Salaries and related costs capitalized for the years ended December 31, 2015 , 2014 and 2013 were $10.4 million , $8.5 million and $7.7 million , respectively. Expenditures for repairs and maintenance are charged to operations as incurred. Significant betterments are capitalized. When assets are sold or retired, their costs and related accumulated depreciation are removed from the accounts with the resulting gains or losses reflected in net income or loss for the period. The Company computes depreciation and amortization on properties using the straight-line method based on estimated useful asset lives. In accordance with ASC 805 “Business Combinations,” the Company allocates the acquisition cost of real estate to its components and depreciates or amortizes these assets (or liabilities) over their useful lives. The amortization of acquired “above-” and “below-market” leases and acquired in-place leases is recorded as an adjustment to revenue and depreciation and amortization, respectively, in the Consolidated Statements of Operations. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows: Land improvements 25 to 40 years Buildings and improvements 10 to 40 years Tenant improvements Shorter of useful life or terms of related lease Furniture, fixtures, and equipment 3 to 7 years Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand and investments with maturities of three months or less from the date of purchase. The majority of the Company’s cash and cash equivalents are held at major commercial banks which may at times exceed the Federal Deposit Insurance Corporation limit of $250,000 . The Company has not experienced any losses to date on its invested cash. Cash Held in Escrows Escrows include amounts established pursuant to various agreements for security deposits, property taxes, insurance and other costs. Escrows also include cash held by qualified intermediaries for possible investments in like-kind exchanges in accordance with Section 1031 of the Internal Revenue Code in connection with sales of the Company’s properties. Investments in Securities The Company accounts for investments in trading securities at fair value, with gains or losses resulting from changes in fair value recognized currently in earnings. The designation of trading securities is generally determined at acquisition. The Company maintains a deferred compensation plan that is designed to allow officers of Boston Properties, Inc. to defer a portion of their current income on a pre-tax basis and receive a tax-deferred return on these deferrals. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2015 and 2014 , the Company had maintained approximately $20.4 million and $19.5 million , respectively, in a separate account, which is not restricted as to its use. The Company recognized gains (losses) of approximately $(0.7) million , $1.0 million and $2.9 million on its investments in the account associated with the Company’s deferred compensation plan during the years ended December 31, 2015 , 2014 and 2013 , respectively. Tenant and Other Receivables Tenant and other accounts receivable, other than accrued rents receivable, are expected to be collected within one year. Deferred Charges Deferred charges include leasing costs and financing fees. Leasing costs include acquired intangible in-place lease values and direct and incremental fees and costs incurred in the successful negotiation of leases, including brokerage, legal, internal leasing employee salaries and other costs which have been deferred and are being amortized on a straight-line basis over the terms of the respective leases. Internal leasing salaries and related costs capitalized for the years ended December 31, 2015 , 2014 and 2013 were $5.5 million , $6.0 million and $5.1 million , respectively. External fees and costs incurred to obtain long-term financing have been deferred and are being amortized over the terms of the respective loans and are included within interest expense. Unamortized financing and leasing costs are charged to expense upon the early repayment or significant modification of the financing or upon the early termination of the lease, respectively. Fully amortized deferred charges are removed from the books upon the expiration of the lease or maturity of the debt. Investments in Unconsolidated Joint Ventures The Company consolidates variable interest entities (“VIEs”) in which it is considered to be the primary beneficiary. VIEs are entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or that the holders of the equity investment at risk do not have a controlling financial interest. The primary beneficiary is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the variable interest entity’s performance, and (2) the obligation to absorb losses and right to receive the returns from the variable interest entity that would be significant to the variable interest entity. For ventures that are not VIEs the Company consolidates entities for which it has significant decision making control over the ventures’ operations. The Company’s judgment with respect to its level of influence or control of an entity involves the consideration of various factors including the form of the Company’s ownership interest, its representation in the entity’s governance, the size of its investment (including loans), estimates of future cash flows, its ability to participate in policy making decisions and the rights of the other investors to participate in the decision making process and to replace the Company as manager and/or liquidate the venture, if applicable. The Company’s assessment of its influence or control over an entity affects the presentation of these investments in the Company’s consolidated financial statements. In addition to evaluating control rights, the Company consolidates entities in which the outside partner has no substantive kick-out rights to remove the Company as the managing member. Accounts of the consolidated entity are included in the accounts of the Company and the noncontrolling interest is reflected on the Consolidated Balance Sheets as a component of equity or in temporary equity between liabilities and equity. Investments in unconsolidated joint ventures are recorded initially at cost, and subsequently adjusted for equity in earnings and cash contributions and distributions. Any difference between the carrying amount of these investments on the balance sheet and the underlying equity in net assets is amortized as an adjustment to equity in earnings of unconsolidated joint ventures over the life of the related asset. Under the equity method of accounting, the net equity investment of the Company is reflected within the Consolidated Balance Sheets, and the Company’s share of net income or loss from the joint ventures is included within the Consolidated Statements of Operations. The joint venture agreements may designate different percentage allocations among investors for profits and losses; however, the Company’s recognition of joint venture income or loss generally follows the joint venture’s distribution priorities, which may change upon the achievement of certain investment return thresholds. The Company may account for cash distributions in excess of its investment in an unconsolidated joint venture as income when the Company is not the general partner in a limited partnership and when the Company has neither the requirement nor the intent to provide financial support to the joint venture. The Company’s investments in unconsolidated joint ventures are reviewed for impairment periodically and the Company records impairment charges when events or circumstances change indicating that a decline in the fair values below the carrying values has occurred and such decline is other-than-temporary. The ultimate realization of the investment in unconsolidated joint ventures is dependent on a number of factors, including the performance of each investment and market conditions. The Company will record an impairment charge if it determines that a decline in the value below the carrying value of an investment in an unconsolidated joint venture is other-than-temporary. To the extent that the Company contributes assets to a joint venture, the Company’s investment in the joint venture is recorded at the Company’s cost basis in the assets that were contributed to the joint venture. To the extent that the Company’s cost basis is different than the basis reflected at the joint venture level, the basis difference is amortized over the life of the related asset and included in the Company’s share of equity in net income of the joint venture. In accordance with the provisions of ASC 970-323 “Investments—Equity Method and Joint Ventures” (“ASC 970-323”), the Company will recognize gains on the contribution of real estate to joint ventures, relating solely to the outside partner’s interest, to the extent the economic substance of the transaction is a sale. The combined summarized financial information of the unconsolidated joint ventures is disclosed in Note 5 . Revenue Recognition In general, the Company commences rental revenue recognition when the tenant takes possession of the leased space and the leased space is substantially ready for its intended use. Contractual rental revenue is reported on a straight-line basis over the terms of the respective leases. The impact of the straight-line rent adjustment increased revenue by approximately $80.0 million , $63.1 million and $65.8 million for the years ended December 31, 2015 , 2014 and 2013 , respectively, as the revenue recorded exceeded amounts billed. Accrued rental income, as reported on the Consolidated Balance Sheets, represents cumulative rental income earned in excess of rent payments received pursuant to the terms of the individual lease agreements. The Company maintains an allowance against accrued rental income for future potential tenant credit losses. The credit assessment is based on the estimated accrued rental income that is recoverable over the term of the lease. The Company also maintains an allowance for doubtful accounts for estimated losses resulting from the inability of tenants to make required rent payments. The computation of this allowance is based on the tenants’ payment history and current credit status, as well as certain industry or geographic specific credit considerations. If the Company’s estimates of collectability differ from the cash received, then the timing and amount of the Company’s reported revenue could be impacted. The credit risk is mitigated by the high quality of the Company’s existing tenant base, reviews of prospective tenants’ risk profiles prior to lease execution and consistent monitoring of the Company’s portfolio to identify potential problem tenants. In accordance with ASC 805, the Company recognizes acquired in-place “above-” and “below-market” leases at their fair values as rental revenue over the original term of the respective leases. The impact of the acquired in-place “above-” and “below-market” leases increased revenue by approximately $35.9 million , $48.3 million and $28.0 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands). Accrued rental income as reported on the Consolidated Balance Sheets represents rental income recognized in excess of rent payments actually received pursuant to the terms of the individual lease agreements. Acquired Above-Market Lease Intangibles Acquired Below-Market Lease Intangibles 2016 $ 14,210 $ 43,809 2017 11,756 33,112 2018 8,637 31,272 2019 7,106 26,434 2020 5,400 9,852 Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized as revenue in the period during which the expenses are incurred. Tenant reimbursements are recognized and presented in accordance with guidance in ASC 605-45 “Principal Agent Considerations” (“ASC 605-45”). ASC 605-45 requires that these reimbursements be recorded on a gross basis, as the Company is generally the primary obligor with respect to purchasing goods and services from third-party suppliers, has discretion in selecting the supplier and has credit risk. The Company also receives reimbursement of payroll and payroll related costs from third parties which the Company reflects on a net basis. The Company’s parking revenues are derived from leases, monthly parking and transient parking. The Company recognizes parking revenue as earned. The Company’s hotel revenues are derived from room rentals and other sources such as charges to guests for telephone service, movie and vending commissions, meeting and banquet room revenue and laundry services. Hotel revenues are recognized as earned. The Company receives management and development fees from third parties. Property management fees are recorded and earned based on a percentage of collected rents at the properties under management, and not on a straight-line basis, because such fees are contingent upon the collection of rents. The Company records development fees as earned depending on the risk associated with each project. Profit on development fees earned from joint venture projects is recognized as revenue to the extent of the third party partners’ ownership interest. Gains on sales of real estate are recognized pursuant to the provisions included in ASC 360-20 “Real Estate Sales” (“ASC 360-20”). The specific timing of the sale is measured against various criteria in ASC 360-20 related to the terms of the transaction and any continuing involvement in the form of management or financial assistance associated with the properties. If the sales criteria for the full accrual method are not met, the Company defers some or all of the gain recognition and accounts for the continued operations of the property by applying the finance, leasing, profit sharing, deposit, installment or cost recovery methods, as appropriate, until the sales criteria are met. Ground Leases The Company has non-cancelable ground lease obligations with various initial term expiration dates through 2114 . The Company recognizes ground rent expense on a straight-line basis over the terms of the respective ground lease agreements. The future contractual minimum lease payments to be made by the Company as of December 31, 2015 , under non-cancelable ground leases which expire on various dates through 2114 , are as follows: Years Ending December 31, (in thousands) 2016 $ 15,188 2017 30,658 2018 11,507 2019 9,693 2020 9,870 Thereafter 594,701 The table includes the Company’s 99 -year ground and air rights lease related to its 200 Clarendon Street property’s adjacent 100 Clarendon Street garage and Back Bay Station concourse level. The Company expects to incur the remaining contractual ground lease payments aggregating approximately $28.9 million over the next three years with no payments thereafter. The Company is recognizing these amounts on a straight-line basis over the 99-year term of the ground and air rights lease (See Note 3). Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income available to common shareholders, as adjusted for undistributed earnings (if any) of certain securities issued by Boston Properties Limited Partnership, by the weighted average number of shares of Common Stock outstanding during the year. Diluted EPS reflects the potential dilution that could occur from shares issuable in connection with awards under stock-based compensation plans, including upon the exercise of stock options, and securities of Boston Properties Limited Partnership that are exchangeable for Common Stock. Earnings Per Common Unit Basic earnings per common unit is computed by dividing net income available to common unitholders, as adjusted for undistributed earnings (if any) of certain securities issued by Boston Properties Limited Partnership, by the weighted average number of common units outstanding during the year. Diluted earnings per common unit reflects the potential dilution that could occur from units issuable in connection with awards under Boston Properties, Inc.’s stock-based compensation plans, including upon the exercise of stock options, and conversion of preferred units of Boston Properties Limited Partnership. Fair Value of Financial Instruments The carrying values of cash and cash equivalents, marketable securities, escrows, receivables, accounts payable, accrued expenses and other assets and liabilities are reasonable estimates of their fair values because of the short maturities of these instruments. The Company follows the authoritative guidance for fair value measurements when valuing its financial instruments for disclosure purposes. Boston Properties Limited Partnership determines the fair value of its unsecured senior notes using market prices. The inputs used in determining the fair value of Boston Properties Limited Partnership’s unsecured 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 it uses quoted market rates to value these instruments. However, the inputs used in determining the fair value could be categorized at a level 2 basis if trading volumes are low. The Company determines the fair value of its mortgage notes payable using discounted cash flow analyses by discounting the spread between the future contractual interest payments and hypothetical future interest payments on mortgage debt based on current market rates for similar securities. In determining the current market rates, the Company adds its estimates of market spreads to the quoted yields on federal government treasury securities with similar maturity dates to its debt. The inputs used in determining the fair value of the Company’s mortgage notes payable and mezzanine notes payable are categorized at a level 3 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company considers the rates used in the valuation techniques to be unobservable inputs. Because the Company’s valuations of its financial instruments are based on these types of estimates, the actual fair values of its financial instruments may differ materially if the Company’s estimates do not prove to be accurate. The following table presents the aggregate carrying value of the Company’s indebtedness and the Company’s corresponding estimate of fair value as of December 31, 2015 and December 31, 2014 (in thousands): December 31, 2015 December 31, 2014 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Mortgage notes payable $ 3,438,714 $ 3,503,746 $ 4,309,484 $ 4,449,541 Mezzanine notes payable 308,482 306,103 309,796 306,156 Unsecured senior notes 5,289,317 5,547,738 5,287,704 5,645,819 Total $ 9,036,513 $ 9,357,587 $ 9,906,984 $ 10,401,516 Derivative Instruments and Hedging Activities Derivative instruments and hedging activities require management to make judgments on the nature of its derivatives and their effectiveness as hedges. These judgments determine if the changes in fair value of the derivative instruments are reported in the Consolidated Statements of Operations as a component of net income or as a component of comprehensive income and as a component of equity on the Consolidated Balance Sheets. While management believes its judgments are reasonable, a change in a derivative’s effectiveness as a hedge could materially affect expenses, net income and equity. The Company accounts for the effective portion of changes in the fair value of a derivative in other comprehensive income (loss) and subsequently reclassifies the effective portion to earnings over the term that the hedged transaction affects earnings. The Company accounts for the ineffective portion of changes in the fair value of a derivative directly in earnings. Stock-Based Employee Compensation Plans At December 31, 2015 , the Company has a stock-based employee compensation plan. Effective January 1, 2005, the Company adopted early ASC 718 “Compensation – Stock Compensation” (“ASC 718”), which revised the fair value based method of accounting for share-based payment liabilities, forfeitures and modifications of stock-based awards and clarified previous guidance in several areas, including measuring fair value, classifying an award as equity or as a liability and attributing compensation cost to reporting periods. Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. These estimates include such items as depreciation and allowances for doubtful accounts. Actual results could differ from those estimates. Recent Accounting Pronouncements On April 10, 2014, the FASB issued ASU 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity” (“ASU 2014-08”). ASU 2014-08 clarifies that discontinued operations presentation applies only to disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results (e.g., a disposal of a major geographical area, a major line of business, a major equity method investment or other major parts of an entity). ASU 2014-08 is effective prospectively for reporting periods beginning after December 15, 2014. Early adoption is permitted, and the Company early adopted ASU 2014-08 during the first quarter of 2014. The Company’s adoption of ASU 2014-08 resulted in the operating results and gains on sales of real estate from the operating properties sold during the years ended December 31, 2015 and 2014 not being reflected as Discontinued Operations in the Company’s Consolidated Statements of Operations (See Note 3 ). In February 2015, the FASB issued ASU 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis” (“ASU 2015-02”). ASU 2015-02 affects reporting entities that are required to evaluate whether they should consolidate certain legal entities. ASU 2015-02 modifies the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities, eliminates the presumption that a general partner should consolidate a limited partnership and affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. ASU 2015-02 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. A reporting entity may apply the amendments in ASU 2015-02 using: (a) a modified retrospective approach by recording a cumulative-effect adjustment to equity as of the beginning of the fiscal year of adoption

Real Estate

Real Estate	12 Months Ended
	Dec. 31, 2015
Real Estate [Abstract]
Real Estate	3. Real Estate Boston Properties, Inc. Real estate consisted of the following at December 31 (in thousands): 2015 2014 Land $ 4,806,021 $ 4,785,772 Land held for future development 252,195 268,114 Buildings and improvements 11,709,285 11,666,105 Tenant improvements 1,920,247 1,752,115 Furniture, fixtures and equipment 29,852 27,986 Construction in progress 763,935 736,311 Total 19,481,535 19,236,403 Less: Accumulated depreciation (3,925,894 ) (3,547,659 ) $ 15,555,641 $ 15,688,744 Boston Properties Limited Partnership Real estate consisted of the following at December 31 (in thousands): 2015 2014 Land $ 4,700,793 $ 4,680,181 Land held for future development 252,195 268,114 Buildings and improvements 11,394,119 11,349,851 Tenant improvements 1,920,247 1,752,115 Furniture, fixtures and equipment 29,852 27,986 Construction in progress 763,935 736,311 Total 19,061,141 18,814,558 Less: Accumulated depreciation (3,846,816 ) (3,476,321 ) $ 15,214,325 $ 15,338,237 Ground and Air Rights Lease On July 31, 2015, the Company entered into a 99 -year ground and air rights lease (the “Lease”) with the Massachusetts Department of Transportation (“MDOT”) with respect to the parking garage located at 100 Clarendon Street (the “Clarendon Garage”) and the concourse level of the Massachusetts Bay Transportation Authority’s Back Bay Station (the “Station”). The Lease amends and restates the air rights lease which the Company had assumed in 2010 at the time it acquired its interests in both the Clarendon Garage and the office tower located at 200 Clarendon Street (formerly known as the John Hancock Tower). The Lease requires the Company to pay a total of approximately $37.0 million and provides the Company with options to acquire certain air rights above both the Clarendon Garage and the Station with the amount of developable square footage associated with the air rights to be determined at a later date. The previous lease had 45 years remaining in its term. Upon execution of the Lease, the Company made a $5.0 million payment and the Lease requires the Company’s remaining obligation to be used to fund improvements to the Station. Development/Redevelopment On May 1, 2015, the Company commenced the redevelopment of Reservoir Place North, a Class A office project with approximately 73,000 net rentable square feet located in Waltham, Massachusetts. On July 23, 2015, the Company commenced construction of its Cambridge Residential project, a residential project aggregating approximately 164,000 square feet comprised of 274 apartment units and approximately 9,000 square feet of retail space located in Cambridge, Massachusetts. On August 13, 2015, the Company acquired an approximately 8,700 square foot parcel of land necessary for the development for a purchase price of approximately $2.0 million . On July 23, 2015, the Company commenced construction of its Reston Signature Site project, a residential project aggregating approximately 514,000 square feet comprised of 508 apartment units and approximately 24,000 square feet of retail space located in Reston Town Center in Reston, Virginia. On August 14, 2015, the Company partially placed in-service 601 Massachusetts Avenue, a Class A office project with approximately 478,000 net rentable square feet located in Washington, DC. On September 10, 2015, the Company partially placed in-service The Point (formerly 99 Third Avenue), a retail project with approximately 16,000 net rentable square feet of retail space located in Waltham, Massachusetts. This project was completed and fully placed in-service on November 1, 2015. On November 1, 2015, the Company completed and fully placed in-service 535 Mission Street, a Class A office project with approximately 307,000 net rentable square feet located in San Francisco, California. On December 2, 2015, the Company completed and fully placed in-service 690 Folsom Street, an office and retail project with approximately 26,000 net rentable square feet located in San Francisco, California. Dispositions On February 19, 2015, the Company completed the sale of a parcel of land within its Washingtonian North property located in Gaithersburg, Maryland for a gross sale price of $8.7 million . Net cash proceeds totaled approximately $8.4 million , resulting in a gain on sale of real estate totaling approximately $3.5 million . The parcel contains approximately 8.5 acres of the Company’s approximately 27 acre property. On March 17, 2015, the Company completed the sale of its Residences on The Avenue property located in Washington, DC for a gross sale price of $196.0 million . Net cash proceeds totaled approximately $192.5 million , resulting in a gain on sale of real estate totaling approximately $91.4 million . The Company has agreed to provide net operating income support of up to $6.0 million if the property’s net operating income fails to achieve certain thresholds. This amount has been recorded as a reduction to the gain on sale. The Residences on The Avenue is comprised of 335 apartment units and approximately 50,000 net rentable square feet of retail space, subject to a ground lease that expires on February 1, 2068. The Residences on The Avenue contributed approximately $1.1 million of net income to the Company for the period from January 1, 2015 through March 16, 2015 and $2.7 million and $4.4 million for the years ended December 31, 2014 and 2013, respectively. On September 18, 2015, a consolidated entity in which the Company has a 50% interest completed the sale of its 505 9th Street, N.W. property located in Washington, DC for approximately $318.0 million , including the assumption by the buyer of approximately $117.0 million of mortgage indebtedness (See Note 6 ). 505 9th Street, N.W. is an approximately 322,000 net rentable square foot Class A office building. Net cash proceeds totaled approximately $194.6 million , of which the Company’s share was approximately $97.3 million . The Company recognized a gain on sale of real estate totaling approximately $199.5 million and $199.7 million for Boston Properties, Inc. and Boston Properties Limited Partnership, respectively, of which approximately $101.1 million was allocated to the outside partners and is included within Noncontrolling Interests in Property Partnerships in the Company’s Consolidated Statements of Operations (See Note 11 ). 505 9th Street, N.W. contributed approximately $2.3 million of net income to the Company for the period from January 1, 2015 through September 17, 2015 and $2.3 million and $1.9 million of net income for the years ended December 31, 2014 and 2013, respectively. On October 1, 2015, the Company completed the sale of an additional parcel of land within its Washingtonian North property located in Gaithersburg, Maryland for a gross sale price of approximately $13.3 million . Net cash proceeds, which included reimbursements for certain infrastructure costs, totaled approximately $13.8 million , resulting in a gain on sale of real estate totaling approximately $2.0 million . The parcel sold consisted of approximately 5.8 acres of the Company’s remaining approximately 18.3 acre property. On December 17, 2015, the Company completed the sale of its Innovation Place property for a gross sale price of $207.0 million . Net cash proceeds totaled approximately $199.3 million , resulting in a gain on sale of real estate totaling approximately $79.1 million and $80.1 million for Boston Properties, Inc. and Boston Properties Limited Partnership, respectively. Innovation Place, located in San Jose, California, is a 26 -acre site with one occupied and three vacant existing office buildings and a total of approximately 574,000 square feet (approximately 463,000 square feet of which are vacant) located at 3100-3130 Zanker Road. The remainder of the site is currently used for 1,699 surface parking spaces, but the land supports an additional 537,000 square feet of office/R&D development and two parking structures with a total of approximately 3,000 parking spaces. Innovation Place contributed approximately $3.5 million of net loss to the Company for the period from January 1, 2015 through December 16, 2015 and $(3.1) million and $0.4 million of net income (loss) for the years ended December 31, 2014 and 2013, respectively. The Company did not have any dispositions during the years ended December 31, 2015 and 2014 that qualified for discontinued operations presentation subsequent to its adoption of ASU 2014-08. The following table summarizes the income from discontinued operations related to One Preserve Parkway, 10 & 20 Burlington Mall Road, 1301 New York Avenue, 303 Almaden Boulevard and Montvale Center and the related gains on sales of real estate, gain on forgiveness of debt and impairment loss for the year ended December 31, 2013: Boston Properties, Inc. For the year ended December 31, 2013 (in thousands) Total revenue $ 20,138 Expenses Operating 6,996 Depreciation and amortization 4,760 Total expenses 11,756 Operating income 8,382 Other expense Interest expense 360 Income from discontinued operations $ 8,022 Noncontrolling interest in income from discontinued operations – common units of the Operating Partnership (803 ) Income from discontinued operations attributable to Boston Properties, Inc. $ 7,219 Gains on sales of real estate from discontinued operations $ 112,829 Gain on forgiveness of debt from discontinued operations 20,182 Impairment loss from discontinued operations (3,241 ) Noncontrolling interest in gains on sales of real estate, gain on forgiveness of debt and impairment loss from discontinued operations – common units of the Operating Partnership (13,348 ) Gains on sales of real estate, gain on forgiveness of debt and impairment loss from discontinued operations attributable to Boston Properties, Inc. $ 116,422 Boston Properties Limited Partnership For the year ended December 31, 2013 (in thousands) Total revenue $ 20,138 Expenses Operating 6,996 Depreciation and amortization 4,760 Total expenses 11,756 Operating income 8,382 Other expense Interest expense 360 Income from discontinued operations attributable to Boston Properties Limited Partnership $ 8,022 Gains on sales of real estate from discontinued operations attributable to Boston Properties Limited Partnership $ 115,459 Gain on forgiveness of debt from discontinued operations attributable to Boston Properties Limited Partnership $ 20,736 Impairment loss from discontinued operations attributable to Boston Properties Limited Partnership $ (2,852 ) Prior Year Acquisitions Included in Pro Forma Information The accompanying unaudited pro forma information for the year ended December 31, 2013 is presented as if the operating property acquisitions of (1) Mountain View Research Park and Mountain View Technology Park on April 10, 2013 and the approximately $26.5 million gain on consolidation and (2) 767 Fifth Avenue (the General Motors Building) on May 31, 2013 and the approximately $359.5 million gain on consolidation, had occurred on January 1, 2012. This unaudited pro forma information is based upon the historical consolidated financial statements of the Company and should be read in conjunction with the consolidated financial statements and notes thereto. This pro forma information does not purport to represent what the actual results of operations of the Company would have been had the above occurred, nor do they purport to predict the results of operations of future periods. Additional information for these transactions are provided below. Boston Properties, Inc. Pro Forma (Unaudited) Year ended December 31, 2013 (in thousands, except per share data) Total revenue $ 2,257,098 Income from continuing operations $ 302,354 Net income attributable to Boston Properties, Inc. $ 400,017 Basic earnings per share: Net income per share attributable to Boston Properties, Inc. $ 2.58 Diluted earnings per share: Net income per share attributable to Boston Properties, Inc. $ 2.57 Boston Properties Limited Partnership Pro Forma (Unaudited) Year ended December 31, 2013 (in thousands, except per unit data) Total revenue $ 2,257,098 Income from continuing operations $ 314,307 Net income attributable to Boston Properties Limited Partnership $ 452,813 Basic earnings per unit: Net income per unit attributable to Boston Properties Limited Partnership $ 2.68 Diluted earnings per unit: Net income per unit attributable to Boston Properties Limited Partnership $ 2.67 On April 10, 2013, the Company acquired the Mountain View Research Park and Mountain View Technology Park properties from Boston Properties Office Value-Added Fund, L.P. (the “Value-Added Fund”) for an aggregate net purchase price of approximately $233.1 million . Mountain View Research Park is a 16 -building complex of Office/Technical properties aggregating approximately 604,000 net rentable square feet. Mountain View Technology Park is a seven -building complex of Office/Technical properties aggregating approximately 135,000 net rentable square feet. The following table summarizes the allocation of the aggregate purchase price of Mountain View Research Park and Mountain View Technology Park at the date of acquisition (in thousands) in accordance with the guidance in ASC 805 “Business Combinations.” Land $ 126,521 Building and improvements 82,451 Tenant improvements 7,326 In-place lease intangibles 23,279 Above-market rents 843 Below-market rents (7,336 ) Net assets acquired $ 233,084 On May 31, 2013, the Company’s two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties. 767 Fifth Avenue (the General Motors Building) is a Class A office property totaling approximately 1.8 million net rentable square feet. In connection with the transfer, the Company and its new joint venture partners modified the Company’s relative decision making authority and consent rights with respect to the joint venture’s assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that, effective as of May 31, 2013, the Company accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting (See Note 11 ). The following table summarizes the allocation of the aggregate purchase price of 767 Fifth Avenue (the General Motors Building) at the date of consolidation on May 31, 2013 (in thousands) in accordance with the guidance in ASC 805 “Business Combinations.” Real estate and related intangibles recorded upon consolidation Land $ 1,796,252 Building and improvements 1,447,446 Tenant improvements 85,208 In-place lease intangibles 357,781 Above market rents 101,897 Below market rents (239,641 ) Above market assumed debt adjustments (192,943 ) $ 3,356,000 Debt recorded upon consolidation Mortgage notes payable $ (1,300,000 ) Mezzanine notes payable (306,000 ) Members’ notes payable (450,000 ) (1) $ (2,056,000 ) Working capital recorded upon consolidation Cash and cash equivalents $ 79,468 Cash held in escrows 2,403 Tenant and other receivables 7,104 Prepaid expenses and other assets 4,269 Accounts payable and accrued expenses (2,418 ) Accrued interest payable (182,369 ) (2) Other liabilities (6,304 ) $ (97,847 ) Noncontrolling interest recorded upon consolidation Noncontrolling interests $ (520,000 ) Noncontrolling interests - working capital 39,139 $ (480,861 ) Net assets recorded upon consolidation $ 721,292 _______________ (1) The Company’s member loan totaling $270.0 million eliminates in consolidation. (2) The Company’s share of the accrued interest payable on the members’ loans totaling approximately $105.5 million eliminates in consolidation. Mountain View Research Park and Mountain View Technology Park contributed approximately $16.7 million of revenue and approximately $0.4 million of earnings to the Company for the period from April 10, 2013 through December 31, 2013. 767 Fifth Avenue (the General Motors Building) contributed approximately $168.4 million of revenue and approximately $8.4 million of earnings to the Company for the period from May 31, 2013 through December 31, 2013.

Deferred Charges

Deferred Charges	12 Months Ended
	Dec. 31, 2015
Deferred Charges [Abstract]
Deferred Charges	4. Deferred Charges Deferred charges consisted of the following at December 31 (in thousands): 2015 2014 Leasing costs, including lease related intangibles $ 1,123,105 $ 1,234,192 Financing costs 61,402 69,127 1,184,507 1,303,319 Less: Accumulated amortization (451,670 ) (471,575 ) $ 732,837 $ 831,744 The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands). Acquired In-Place Lease Intangibles 2016 $ 52,456 2017 36,438 2018 31,913 2019 26,067 2020 13,325

Investments in Unconsolidated J

Investments in Unconsolidated Joint Ventures	12 Months Ended
	Dec. 31, 2015
Investments In Unconsolidated Joint Ventures [Abstract]
Investments In Unconsolidated Joint Ventures	5. Investments in Unconsolidated Joint Ventures The investments in unconsolidated joint ventures consist of the following at December 31, 2015 and 2014: Carrying Value of Investment (1) Entity Properties Nominal % Ownership December 31, December 31, (in thousands) Square 407 Limited Partnership Market Square North 50.0 % $ (9,951 ) $ (8,022 ) The Metropolitan Square Associates LLC Metropolitan Square 51.0 % 9,179 8,539 BP/CRF 901 New York Avenue LLC 901 New York Avenue 25.0 % (2) (11,958 ) (1,080 ) WP Project Developer LLC Wisconsin Place Land and Infrastructure 33.3 % (3) 43,524 45,514 Annapolis Junction NFM, LLC Annapolis Junction 50.0 % (4) 29,009 25,246 540 Madison Venture LLC 540 Madison Avenue 60.0 % 68,983 68,128 500 North Capitol LLC 500 North Capitol Street, NW 30.0 % (3,292 ) (2,250 ) 501 K Street LLC 1001 6th Street 50.0 % (5) 42,584 41,736 Podium Developer LLC The Hub on Causeway 50.0 % 18,508 4,231 1265 Main Office JV LLC 1265 Main Street 50.0 % 11,916 N/A BNY Tower Holdings LLC Dock72 at the Brooklyn Navy Yard 50.0 % 11,521 N/A $ 210,023 $ 182,042 _______________ (1) Investments with deficit balances aggregating approximately $25.2 million and $11.4 million at December 31, 2015 and 2014, respectively, have been reflected within Other Liabilities on the Company's Consolidated Balance Sheets. (2) The Company’s economic ownership has increased based on the achievement of certain return thresholds. (3) The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land, parking garage and infrastructure of the project. (4) The joint venture owns four in-service buildings and two undeveloped land parcels. (5) Under the joint venture agreement, the partner may be entitled to up to two additional payments from the venture based on increases in total square footage of the project above 520,000 square feet and achieving certain project returns at stabilization. Certain of the Company’s unconsolidated 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: December 31, December 31, (in thousands) ASSETS Real estate and development in process, net $ 1,072,412 $ 1,034,552 Other assets 256,055 264,097 Total assets $ 1,328,467 $ 1,298,649 LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY Mortgage and notes payable $ 833,895 $ 830,075 Other liabilities 44,549 34,211 Members’/Partners’ equity 450,023 434,363 Total liabilities and members’/partners’ equity $ 1,328,467 $ 1,298,649 Company’s share of equity $ 237,070 $ 209,828 Basis differentials (1) (27,047 ) (27,786 ) Carrying value of the Company’s investments in unconsolidated joint ventures (2) $ 210,023 $ 182,042 _______________ (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. (2) Investments with deficit balances aggregating approximately $25.2 million and $11.4 million at December 31, 2015 and 2014 , respectively, have been reflected within Other Liabilities on the Company's Consolidated Balance Sheets. The combined summarized statements of operations of the Company’s joint ventures are as follows: For the year ended December 31, 2015 2014 2013 (in thousands) Total revenue (1) $ 155,642 $ 158,161 $ 311,548 Expenses Operating 65,093 62,974 105,319 Depreciation and amortization 36,057 37,041 86,088 Total expenses 101,150 100,015 191,407 Operating income 54,492 58,146 120,141 Other income (expense) Interest expense (32,176 ) (31,896 ) (112,535 ) Losses from early extinguishments of debt — — (1,677 ) Income from continuing operations 22,316 26,250 5,929 Gains on sales of real estate — — 14,207 Net income $ 22,316 $ 26,250 $ 20,136 Company’s share of net income $ 22,031 (2) $ 11,913 $ 4,612 Gains on sales of real estate — — 54,501 Basis differential 739 856 (1,017 ) Elimination of inter-entity interest on partner loan — — 16,978 Income from unconsolidated joint ventures $ 22,770 $ 12,769 $ 75,074 Gains on consolidation of joint ventures $ — $ — $ 385,991 _______________ (1) Includes straight-line rent adjustments of $3.9 million , $3.0 million and $7.8 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. Includes net above-/below-market rent adjustments of $(0.2) million , $(0.1) million and $33.7 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. (2) During the year ended December 31, 2015, the Company received a distribution of approximately $24.5 million , which was generated from the excess loan proceeds from the refinancing of 901 New York Avenue’s mortgage loan to a new 10 -year mortgage loan totaling $225.0 million . The Company’s allocation of income and distributions for the year ended December 31 2015 was not proportionate to its nominal ownership interest as a result of the achievement of specified investment return thresholds, as provided for in the joint venture agreement. On May 8, 2015, the Company entered into a joint venture with an unrelated third party to redevelop an existing building into a Class A office building totaling approximately 115,000 net rentable square feet at 1265 Main Street in Waltham, Massachusetts. The joint venture partner contributed real estate and improvements, with an aggregate fair value of approximately $9.4 million , for its initial 50% interest in the joint venture. For its initial 50% interest, the Company will contribute cash totaling approximately $9.4 million as the joint venture incurs costs. The joint venture has entered into a fifteen -year lease with a tenant to occupy 100% of the building. On June 26, 2015, the Company entered into a joint venture with an unrelated third party to develop Dock72, an office building totaling approximately 670,000 net rentable square feet located at the Brooklyn Navy Yard in Brooklyn, New York. Each partner contributed cash totaling approximately $9.1 million for their initial 50% interest in the joint venture. The joint venture entered into a 96 -year ground lease, comprised of an initial term of 46 years, which may be extended by the joint venture to 2111, subject to certain conditions. The joint venture also entered into a 20 -year lease with a tenant to occupy approximately 222,000 net rentable square feet at the building. In addition, the joint venture entered into an option agreement pursuant to which it may lease an additional land parcel at the site, which could support between 600,000 and 1,000,000 net rentable square feet of development. In connection with the execution of the option agreement, the joint venture paid a non-refundable option payment of $1.0 million . On September 22, 2015, a joint venture in which the Company has a 50% interest completed and fully placed in-service Annapolis Junction Building Seven, a Class A office project with approximately 127,000 net rentable square feet located in Annapolis, Maryland. On September 30, 2015, a joint venture in which the Company has a 50% interest extended the loan collateralized by its Annapolis Junction Building Six property. At the time of the extension, the outstanding balance of the construction loan totaled approximately $13.4 million and was scheduled to mature on November 17, 2015. The extended loan has a total commitment amount of $15.9 million , bears interest at a variable rate equal to LIBOR plus 2.25% per annum and matures on November 17, 2016 . Annapolis Junction Building Six is a Class A office property with approximately 119,000 net rentable square feet located in Annapolis, Maryland. On October 22, 2015, a joint venture in which the Company has a 50% interest commenced construction of the Hub on Causeway at North Station containing approximately 385,000 net rentable square feet of retail and office space located in Boston, Massachusetts. On December 22, 2015, a joint venture in which the Company has a 50% interest completed and fully placed in-service Annapolis Junction Building Eight, a Class A office project with approximately 126,000 net rentable square feet located in Annapolis, Maryland.

Mortgage Notes Payable

Mortgage Notes Payable	12 Months Ended
	Dec. 31, 2015
Loans Payable [Abstract]
Mortgage Notes Payable	6. Mortgage Notes Payable The Company had outstanding mortgage notes payable totaling approximately $3.4 billion and $4.3 billion as of December 31, 2015 and 2014 , respectively, each collateralized by one or more buildings and related land included in real estate assets. The mortgage notes payable are generally due in monthly installments and mature at various dates through April 10, 2022 . Fixed rate mortgage notes payable totaled approximately $3.4 billion and $4.3 billion at December 31, 2015 and 2014 , respectively, with contractual interest rates ranging from 4.75% to 7.69% per annum at December 31, 2015 and 2014 (with a weighted-average of 5.69% and 5.70% (excluding the mezzanine notes payable) at December 31, 2015 and 2014 , respectively). There were no variable rate mortgage loans at December 31, 2015 and 2014. As of December 31, 2015 and 2014 , the LIBOR rate was 0.43% and 0.17% , respectively. On September 18, 2015, in connection with the sale of 505 9th Street, N.W. located in Washington, DC by a consolidated entity in which the Company has a 50% interest, the consolidated entity assigned to the buyer the mortgage loan collateralized by the property totaling approximately $117.0 million . The assigned mortgage loan bears interest at a fixed rate of 5.73% per annum and matures on November 1, 2017 (See Note 3 ). On October 1, 2015, the Company used available cash to repay the mortgage loan collateralized by its Kingstowne Two and Kingstowne Retail properties located in Alexandria, Virginia totaling approximately $29.8 million . The mortgage loan bore interest at a fixed rate of 5.99% per annum and was scheduled to mature on January 1, 2016. There was no prepayment penalty. On December 15, 2015, the Company legally defeased the mortgage loan collateralized by its 100 & 200 Clarendon Street (formerly known as the John Hancock Tower and Garage) properties located in Boston, Massachusetts. The mortgage loan had an outstanding principal balance of $640.5 million , bore interest at a fixed rate of 5.68% per annum and was scheduled to mature on January 6, 2017. The cash outlay required for the defeasance in the net amount of approximately $667.3 million was based on the purchase price of U.S. government securities that will generate sufficient cash flow to fund continued interest payments on the loan from the effective date of the defeasance through, and the repayment of the loan on, October 6, 2016, which is the date on which the Company could repay the loan at par. In connection with the defeasance, the mortgage and other liens on the property were extinguished and all existing collateral, including various guarantees, were released. As a result of the defeasance, the Company recognized a loss from early extinguishment of debt of approximately $22.0 million , consisting of approximately $26.8 million , which is the difference between the purchase price for the U.S. government securities acquired for the defeasance and the outstanding principal balance of the mortgage loan, and approximately $1.4 million of unamortized deferred financing costs, offset by approximately $4.8 million from the acceleration of the remaining balance of the historical fair value debt adjustment and approximately $1.4 million of accrued interest expense through the effective date of the defeasance. Two mortgage loans totaling approximately $1.5 billion at December 31, 2015 and four mortgage loans totaling approximately $2.2 billion at December 31, 2014 have been accounted for at their fair values on the dates the mortgage loans were assumed in connection with acquisitions of real estate. The impact of recording the mortgage loans at fair value resulted in a decrease to interest expense of approximately $55.0 million , $52.5 million and $34.4 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. The cumulative liability related to the fair value adjustments was $80.2 million and $138.7 million at December 31, 2015 and 2014 , respectively, and is included in mortgage notes payable in the Consolidated Balance Sheets. Contractual aggregate principal payments of mortgage notes payable at December 31, 2015 are as follows: Principal Payments (in thousands) 2016 $ 576,864 2017 2,067,654 2018 18,633 2019 19,670 2020 20,766 Thereafter 654,892 Total aggregate principal payments 3,358,479 Unamortized balance of historical fair value adjustments 80,235 Total carrying value of mortgage notes payable $ 3,438,714

Derivative and Hedging Instrume

Derivative and Hedging Instruments (Notes)	12 Months Ended
	Dec. 31, 2015
Derivatives and Hedging Activities [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	7. Derivative Instruments and Hedging Activities On February 19, 2015, Boston Properties Limited Partnership commenced a planned interest rate hedging program. During the year ended December 31, 2015, Boston Properties Limited Partnership entered into seventeen forward-starting interest rate swap contracts that fix the 10 -year swap rate at a weighted-average rate of approximately 2.423% per annum on notional amounts aggregating $550.0 million . These interest rate swap contracts were entered into in advance of a financing with a target commencement date in September 2016 and maturity in September 2026. In addition, during the year ended December 31, 2015, 767 Fifth Partners LLC, which is the consolidated entity (in which the Company has a 60% interest and owns 767 Fifth Avenue (the General Motors Building) in New York City), entered into fourteen forward-starting interest rate swap contracts, which fix the 10 -year swap rate at a weighted-average rate of approximately 2.646% per annum on notional amounts aggregating $400.0 million . These interest rate swap contracts were entered into in advance of a financing with a target commencement date in June 2017 and maturity in June 2027 (See Note 20 ). Boston Properties Limited Partnership’s and 767 Fifth Avenue Partners LLC’s interest rate swap contracts consisted of the following at December 31, 2015 (dollars in thousands): Derivative Instrument Aggregate Notional Amount Effective Date Maturity Date Strike Rate Range Balance Sheet Location Fair Value Low High Boston Properties Limited Partnership: Interest Rate Swaps $ 400,000 September 1, 2016 September 1, 2026 2.348 % - 2.571 % Other Liabilities $ (5,419 ) Interest Rate Swaps 150,000 September 1, 2016 September 1, 2026 2.129 % - 2.325 % Prepaid Expenses and Other Assets 1,188 $ 550,000 $ (4,231 ) 767 Fifth Partners LLC: Interest Rate Swaps $ 250,000 June 7, 2017 June 7, 2027 2.677 % - 2.950 % Other Liabilities $ (7,247 ) Interest Rate Swaps 150,000 June 7, 2017 June 7, 2027 2.336 % - 2.430 % Prepaid Expenses and Other Assets 1,176 $ 400,000 $ (6,071 ) $ 950,000 $ (10,302 ) Boston Properties Limited Partnership entered into the interest rate swap contracts designated and qualifying as cash flow hedges to reduce its exposure to the variability in future cash flows attributable to changes in the 10 -year swap rate in contemplation of obtaining 10 -year fixed-rate financing in September 2016. The Company’s 767 Fifth Partners LLC consolidated entity entered into the interest rate swap contracts designated and qualifying as cash flow hedges to reduce its exposure to the variability in future cash flows attributable to changes in the 10 -year swap rate in contemplation of obtaining 10 -year fixed-rate financing in June 2017. Boston Properties Limited Partnership has formally documented all of its relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking various hedge transactions. Boston Properties Limited Partnership also assesses and documents, both at the hedging instrument’s inception and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows associated with the hedged items. All components of the forward-starting interest rate swap contracts were included in the assessment of hedge effectiveness. Boston Properties Limited Partnership has agreements with each of its derivative counterparties that contain a provision where it could be declared in default on its derivative obligations if repayment of its indebtedness is accelerated by the lender due to its default on the indebtedness. As of December 31, 2015 , the fair value of derivatives is in a net liability position, which excludes any adjustment for nonperformance risk and excludes accrued interest, of approximately $11.7 million . As of December 31, 2015 , Boston Properties Limited Partnership has not posted any collateral related to these agreements. If Boston Properties Limited Partnership had breached any of these provisions at December 31, 2015 , it could have been required to settle its obligations under the agreements at their termination value of approximately $11.7 million . The Company accounts for the effective portion of changes in the fair value of a derivative in accumulated other comprehensive loss and subsequently reclassifies the effective portion to earnings over the term that the hedged transaction affects earnings. The Company accounts for the ineffective portion of changes in the fair value of a derivative directly in earnings. During the year ended December 31, 2015 , the Company has recorded the changes in fair value of the swap contracts related to the effective portion of the interest rate contracts aggregating approximately $12.7 million in Other Liabilities and approximately $2.4 million in Prepaid Expenses and Other Assets and Accumulated Other Comprehensive Loss within the Company’s Consolidated Balance Sheets. During the year ended December 31, 2015 , the Company did not record any hedge ineffectiveness. The Company expects that within the next twelve months it will reclassify into earnings as an increase to interest expense approximately $141,000 of the amounts recorded within Accumulated Other Comprehensive Loss relating to the forward-starting interest rate swap contracts in effect and as of December 31, 2015 . The following table presents the location in the financial statements of the losses recognized related to the Company’s cash flow hedges for the years ended December 31, 2015 , 2014 and 2013 : Year ended December 31, 2015 2014 2013 (in thousands) Amount of loss related to the effective portion recognized in other comprehensive loss $ (10,302 ) $ — $ — Amount of loss related to the effective portion subsequently reclassified to earnings (1) $ (2,510 ) $ (2,508 ) $ (2,513 ) Amount of gain (loss) related to the ineffective portion and amount excluded from effectiveness testing $ — $ — $ — ___________ (1) Consists of amounts from interest rate hedging programs entered into prior to 2015. Boston Properties, Inc. The following table reflects the changes in accumulated other comprehensive loss for Boston Properties, Inc. for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ (13,817 ) Amortization of interest rate contracts (1) 2,513 Other comprehensive income attributable to noncontrolling interests (252 ) Balance at December 31, 2013 (11,556 ) Amortization of interest rate contracts (1) 2,508 Other comprehensive income attributable to noncontrolling interests (256 ) Balance at December 31, 2014 (9,304 ) Effective portion of interest rate contracts (10,302 ) Amortization of interest rate contracts (1) 2,510 Other comprehensive loss attributable to noncontrolling interests 2,982 Balance at December 31, 2015 $ (14,114 ) ___________ (1) Consists of amounts from interest rate hedging programs entered into prior to 2015. Boston Properties Limited Partnership The following table reflects the changes in accumulated other comprehensive loss for Boston Properties Limited Partnership for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ (17,994 ) Amortization of interest rate contracts (1) 2,513 Balance at December 31, 2013 (15,481 ) Amortization of interest rate contracts (1) 2,508 Balance at December 31, 2014 (12,973 ) Effective portion of interest rate contracts (10,302 ) Amortization of interest rate contracts (1) 2,510 Other comprehensive loss attributable to noncontrolling interests in property partnership 2,428 Balance at December 31, 2015 $ (18,337 ) ___________ (1) Consists of amounts from interest rate hedging programs entered into prior to 2015.

Unsecured Senior Notes

Unsecured Senior Notes	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Unsecured Senior Notes	8. Unsecured Senior Notes The following summarizes the unsecured senior notes outstanding as of December 31, 2015 (dollars in thousands) (See also Note 20 ): Coupon/ Stated Rate Effective Rate(1) Principal Amount Maturity Date(2) 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 5,300,000 Net unamortized discount (10,683 ) Total $ 5,289,317 _______________ (1) Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs. (2) No principal amounts are due prior to maturity. The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60% , (2) a secured debt leverage ratio not to exceed 50% , (3) an interest coverage ratio of greater than 1.50 , and (4) an unencumbered asset value of not less than 150% of unsecured debt. At December 31, 2015 , Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.

Unsecured Line of Credit

Unsecured Line of Credit	12 Months Ended
	Dec. 31, 2015
Unsecured Line of Credit [Abstract]
Unsecured Line of Credit [Text Block]	9. Unsecured Line of Credit Boston Properties Limited Partnership has a $1.0 billion revolving credit facility (the “Unsecured Line of Credit”) with a maturity date of July 26, 2018 . Boston Properties Limited Partnership may increase the total commitment to $1.5 billion , subject to syndication of the increase and other conditions. At Boston Properties Limited 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 Boston Properties Limited 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 Boston Properties Limited 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 Boston Properties Limited Partnership at a reduced interest rate. In addition, Boston Properties Limited 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 Boston Properties Limited 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 Boston Properties Limited 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% . At December 31, 2015 and 2014 , there were no amounts outstanding on the Unsecured Line of Credit. The terms of the Unsecured Line of Credit require that Boston Properties Limited Partnership maintain a number of customary financial and other covenants on an ongoing basis, including: (1) a leverage ratio not to exceed 60% , however, the leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (2) a secured debt leverage ratio not to exceed 55% , (3) a fixed charge coverage ratio of at least 1.40 , (4) an unsecured debt leverage ratio not to exceed 60% , however, the unsecured debt leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (5) an unsecured debt interest coverage ratio of at least 1.75 and (6) limitations on permitted investments. At December 31, 2015 , Boston Properties Limited Partnership was in compliance with each of these financial and other covenant requirements.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	10. 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 $22.8 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. With limited exception, under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners (See Note 11 ). Under certain of the Company’s joint venture agreements, if certain return thresholds are achieved the partners will be entitled to an additional promoted interest or payments. In connection with the assumption of 767 Fifth Avenue’s (the General Motors Building) secured loan by the Company’s consolidated entity, 767 Venture, LLC, the Company guaranteed the consolidated entity’s obligation to fund various escrows, including tenant improvements, taxes and insurance in lieu of cash deposits. At December 31, 2015 , there was no funding obligation under the guarantee. The Company earns a fee from the entity for providing the guarantee and has an agreement with the outside partners to reimburse the consolidated entity for their share of any payments made under the guarantee. In connection with 767 Fifth Partners LLC entering into interest rate swap contracts (See Note 7 ), the Company guaranteed 767 Fifth Partners LLC’s obligations under the hedging agreements in favor of each hedge counterparty. 767 Fifth Partners LLC is the entity that owns 767 Fifth Avenue (the General Motors Building). It is a subsidiary of 767 Venture, LLC, a consolidated entity in which the Company has a 60% interest. The Company earns a fee from the entity for providing the guarantee and has an agreement with the outside partners to reimburse the consolidated entity for their share of any payments made under the guarantee. In connection with the mortgage financing collateralized by the Company’s Fountain Square property located in Reston, Virginia, the Company has agreed to guarantee approximately $0.7 million related to its obligation to provide funds for certain tenant re-leasing costs. The mortgage financing matures on October 11, 2016 . 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 construction completion guarantees for construction loans, environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, misrepresentation and bankruptcy) on certain of its unconsolidated joint venture loans. In 2009, the Company filed a general unsecured creditor’s claim against Lehman Brothers, Inc. for approximately $45.3 million related to its rejection of a lease at 399 Park Avenue in New York City. On January 10, 2014, the trustee for the liquidation of the business of Lehman Brothers allowed the Company’s claim in the amount of approximately $45.2 million . On September 18, 2014, the Company received an initial distribution totaling approximately $7.7 million , which is included in Base Rent in the accompanying Consolidated Statements of Operations for the year ended December 31, 2014. On March 11, 2015, the Company received a second interim distribution totaling approximately $4.5 million , which is included in Base Rent in the accompanying Consolidated Statements of Operations for the year ended December 31, 2015. On September 9, 2015, the Company received a third interim distribution totaling approximately $3.6 million , which is also included in Base Rent in the accompanying Consolidated Statements of Operations for the year ended December 31, 2015, leaving a remaining claim of approximately $29.4 million . The Company will continue to evaluate whether to attempt to sell the remaining claim or wait until the trustee distributes proceeds from the Lehman Brothers estate. Given the inherent uncertainties in bankruptcy proceedings, there can be no assurance as to the timing or amount of additional proceeds, if any, that the Company may ultimately realize on the remaining claim, whether by sale to a third party or by one or more distributions from the trustee. Accordingly, the Company has not recorded any estimated recoveries associated with this gain contingency within its Consolidated Financial Statements at December 31, 2015. Concentrations of Credit Risk Management of the Company performs ongoing credit evaluations of tenants and may require tenants to provide some form of credit support such as corporate guarantees and/or other financial guarantees. Although the Company’s properties are geographically diverse and the tenants operate in a variety of industries, to the extent the Company has a significant concentration of rental revenue from any single tenant, the inability of that tenant to make its lease payments could have an adverse effect on the Company. Some potential losses are not covered by insurance. The Company carries insurance coverage on its properties of types and in amounts and with deductibles that it believes are in line with coverage customarily obtained by owners of similar properties. In response to the uncertainty in the insurance market following the terrorist attacks of September 11, 2001, the Federal Terrorism Risk Insurance Act (as amended, “TRIA”) was enacted in November 2002 to require regulated insurers to make available coverage for “certified” acts of terrorism (as defined by the statute). The expiration date of TRIA was extended to December 31, 2014 by the Terrorism Risk Insurance Program Reauthorization Act of 2007 and further extended to December 31, 2020 by the Terrorism Risk Insurance Program Reauthorization Act of 2015 (“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 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. 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. 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 the Company’s portfolio, including 767 Fifth Avenue, but excluding certain other properties owned in joint ventures with third parties or which the Company manages. The per occurrence limit for NBCR Coverage is $1.0 billion . Under TRIA, after the payment of the required deductible and coinsurance, the NBCR Coverage provided by IXP is backstopped by the Federal Government if the aggregate industry insured losses resulting from a certified act of terrorism exceed a “program trigger.” In 2015, the program trigger was $100 million and the coinsurance was 15% , however, both will increase in subsequent years pursuant to TRIPRA. If the Federal Government pays out for a loss under TRIA, it is mandatory that the Federal Government recoup the full amount of the loss from insurers offering TRIA coverage after the payment of the loss pursuant to a formula in TRIPRA. The Company may elect to terminate the NBCR Coverage if the Federal Government seeks recoupment for losses paid under TRIA, if there is a change in its portfolio or for any other reason. The Company intends to continue to monitor the scope, nature and cost of available terrorism insurance and maintain terrorism insurance in amounts and on terms that are commercially reasonable. The Company also currently carries earthquake insurance on its properties located in areas known to be subject to earthquakes in an amount and subject to self-insurance that the Company believes is 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 Salesforce Tower) with a $170 million per occurrence limit (increased on March 1, 2015 from $120 million ), and a $170 million annual aggregate limit (increased on March 1, 2015 from $120 million ), $20 million of which is provided by IXP, as a direct insurer. The builders risk policy maintained for the development of Salesforce Tower in San Francisco includes a $60 million per occurrence and annual aggregate limit of earthquake coverage. The amount of the Company’s earthquake insurance coverage may not be sufficient to cover losses from earthquakes. In addition, the amount of earthquake coverage could impact the Company’s ability to finance properties subject to earthquake risk. The Company may discontinue earthquake insurance or change the structure of its earthquake insurance program on some or all of its properties in the future if the premiums exceed the Company’s estimation of the value of the coverage. IXP, a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company’s earthquake insurance coverage for its Greater San Francisco properties and the Company’s NBCR Coverage. Insofar as the Company owns IXP, it is responsible for its liquidity and capital resources, and the accounts of IXP 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 would also be responsible for any recoupment charges by the Federal Government in the event losses are paid out and its insurance policy is maintained after the payout by the Federal Government. If the Company experiences a loss and IXP is required to pay under its insurance policy, the Company would ultimately record the loss to the extent of the required payment. Therefore, insurance coverage provided by IXP should not be considered as the equivalent of third-party insurance, but rather as a modified form of self-insurance. In addition, Boston Properties Limited 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. Legal Matters The Company is subject to various legal proceedings and claims that arise in the ordinary course of business. These matters are generally covered by insurance. Management believes that the final outcome of such matters will not have a material adverse effect on the financial position, results of operations or liquidity of the Company. State and Local Tax Matters Because Boston Properties, Inc. is organized and qualifies as a REIT, it is generally not subject to federal income taxes, but is subject to certain state and local taxes. In the normal course of business, certain entities through which the Company owns real estate either have undergone, or are currently undergoing, tax audits. Although the Company believes that it has substantial arguments in favor of its positions in the ongoing audits, in some instances there is no controlling precedent or interpretive guidance on the specific point at issue. Collectively, tax deficiency notices received to date from the jurisdictions conducting the ongoing audits have not been material. However, there can be no assurance that future audits will not occur with increased frequency or that the ultimate result of such audits will not have a material adverse effect on the Company’s results of operations. Environmental Matters It is the Company’s policy to retain independent environmental consultants to conduct or update Phase I environmental assessments (which generally do not involve invasive techniques such as soil or ground water sampling) and asbestos surveys in connection with the Company’s acquisition of properties. These pre-purchase environmental assessments have not revealed environmental conditions that the Company believes will have a material adverse effect on its business, assets, financial condition, results of operations or liquidity, and the Company is not otherwise aware of environmental conditions with respect to its properties that the Company believes would have such a material adverse effect. However, from time to time environmental conditions at the Company’s properties have required and may in the future require environmental testing and/or regulatory filings, as well as remedial action. In February 1999, the Company (through a joint venture) acquired from Exxon Corporation a property in Massachusetts that was formerly used as a petroleum bulk storage and distribution facility and was known by the state regulatory authority to contain soil and groundwater contamination. The Company developed an office park on the property. The Company engaged a specially licensed environmental consultant to oversee the management of contaminated soil and groundwater that was disturbed in the course of construction. Under the property acquisition agreement, Exxon agreed to (1) bear the liability arising from releases or discharges of oil and hazardous substances which occurred at the site prior to the Company’s ownership, (2) continue monitoring and/or remediating such releases and discharges as necessary and appropriate to comply with applicable requirements, and (3) indemnify the Company for certain losses arising from preexisting site conditions. Any indemnity claim may be subject to various defenses, and there can be no assurance that the amounts paid under the indemnity, if any, would be sufficient to cover the liabilities arising from any such releases and discharges. Environmental investigations at some of the Company’s properties and certain properties owned by affiliates of the Company have identified groundwater contamination migrating from off-site source properties. In each case the Company engaged a licensed environmental consultant to perform the necessary investigations and assessments and to prepare any required submittals to the regulatory authorities. In each case the environmental consultant concluded that the properties qualify under the regulatory program or the regulatory practice for a status which eliminates certain deadlines for conducting response actions at a site. The Company also believes that these properties qualify for liability relief under certain statutory provisions or regulatory practices regarding upgradient releases. Although the Company believes that the current or former owners of the upgradient source properties may bear responsibility for some or all of the costs of addressing the identified groundwater contamination, the Company will take such further response actions (if any) that it deems necessary or advisable. Other than periodic testing at some of these properties, no such additional response actions are anticipated at this time. Some of the Company’s properties and certain properties owned by the Company’s affiliates are located in urban, industrial and other previously developed areas where fill or current or historical uses of the areas have caused site contamination. Accordingly, it is sometimes necessary to institute special soil and/or groundwater handling procedures and/or include particular building design features in connection with development, construction and other property operations in order to achieve regulatory closure and/or ensure that contaminated materials are addressed in an appropriate manner. In these situations it is the Company’s practice to investigate the nature and extent of detected contamination, including potential issues associated with contaminant migration, assess potential liability risks and estimate the costs of required response actions and special handling procedures. The Company then uses this information as part of its decision-making process with respect to the acquisition, deal structure and/or development of the property. For example, the Company owns a parcel in Massachusetts which was formerly used as a quarry/asphalt batching facility. Pre-purchase testing indicated that the site contained relatively low levels of certain contaminants. The Company has developed an office park on this property. Prior to and during redevelopment activities, the Company engaged a specially licensed environmental consultant to monitor environmental conditions at the site and prepare necessary regulatory submittals based on the results of an environmental risk characterization. A submittal has been made to the regulatory authorities in order to achieve regulatory closure at this site. The submittal included an environmental deed restriction that mandates compliance with certain protective measures in a portion of the site where low levels of residual soil contamination have been left in place in accordance with applicable laws. The Company expects that resolution of the environmental matters relating to the above will not have a material impact on its business, assets, financial condition, results of operations or liquidity. However, the Company cannot assure you that it has identified all environmental liabilities at its properties, that all necessary remediation actions have been or will be undertaken at the Company’s properties or that the Company will be indemnified, in full or at all, in the event that such environmental liabilities arise. Tax Protection Obligations In connection with the acquisition of 767 Fifth Avenue (the General Motors Building), Boston Properties Limited Partnership entered into an agreement for the benefit of the contributing party which specifically states that Boston Properties Limited Partnership will not sell or otherwise transfer the property in a taxable transaction until June 9, 2017. If Boston Properties Limited Partnership does sell or transfer the property in a taxable transaction, it would be liable to the contributor for contractual damages.

Noncontrolling Interests

Noncontrolling Interests	12 Months Ended
	Dec. 31, 2015
Noncontrolling Interest [Abstract]
Noncontrolling Interests	11. Noncontrolling Interests Noncontrolling interests relate to the interests in Boston Properties Limited Partnership not owned by Boston Properties, Inc. and interests in consolidated property partnerships not wholly-owned by the Company. As of December 31, 2015 , the noncontrolling interests in Boston Properties Limited Partnership consisted of 16,097,473 OP Units, 1,831,714 LTIP Units (including 216,854 2012 OPP Units), 309,818 2013 MYLTIP Units, 476,320 2014 MYLTIP Units and 368,415 2015 MYLTIP Units held by parties other than Boston Properties, Inc. Noncontrolling Interest—Redeemable Preferred Units On March 11, 2014, Boston Properties Limited Partnership notified the holders of the outstanding Series Two Preferred Units that it had elected to redeem all of such Series Two Preferred Units on May 12, 2014. As a result of Boston Properties Limited Partnership election to redeem the units, as of May 12, 2014, the holders of all remaining 666,116 Series Two Preferred Units converted such units into an aggregate of 874,168 OP Units. The Series Two Preferred Units bore 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 were convertible into OP Units at a rate of $38.10 per Preferred Unit ( 1.312336 OP Units for each Preferred Unit). During the year ended December 31, 2013, 329,881 Series Two Preferred Units of Boston Properties Limited Partnership were converted by the holders into 432,914 OP Units. Due to the holders’ redemption option existing outside the control of the Company, the Series Two Preferred Units were presented outside of permanent equity in the Company’s Consolidated Balance Sheets. On June 25, 2015, Boston Properties Limited Partnership redeemed the remaining 12,667 Series Four Preferred Units for cash totaling approximately $0.6 million , plus accrued and unpaid distributions. The Series Four Preferred Units bore a preferred distribution equal to 2.00% per annum on a liquidation preference of $50.00 per unit and were not convertible into OP Units. The holders of Series Four Preferred Units had 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 Boston Properties Limited Partnership to redeem all of their units for cash at the redemption price of $50.00 per unit. Boston Properties Limited Partnership also had 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. In order to secure the performance of certain post-issuance obligations by the holders, all of such outstanding Series Four Preferred Units were subject to forfeiture pursuant to the terms of a pledge agreement and not eligible for redemption until and unless such security interest is released. Boston Properties Limited Partnership’s first right to redeem the Series Four Preferred Units was a 30 -day period beginning on August 29, 2013. On August 29, 2013, Boston Properties Limited Partnership redeemed approximately 861,400 Series Four Preferred Units for cash at the redemption price of $50.00 per unit. On May 19, 2014, Boston Properties Limited Partnership released to the holders 319,687 Series Four Preferred Units that were previously subject to the security interest. On July 3, 2014, Boston Properties Limited Partnership redeemed such units for cash totaling approximately $16.0 million . On October 16, 2014, Boston Properties Limited Partnership released to the holders 27,773 Series Four Preferred Units that were previously subject to the security interest under the pledge agreement. On November 5, 2014, Boston Properties Limited Partnership redeemed such units for cash totaling approximately $1.4 million . Due to the holders’ redemption option existing outside the control of the Company, the Series Four Preferred Units were presented outside of permanent equity in the Company’s Consolidated Balance Sheets. On February 17, 2015, Boston Properties Limited Partnership paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit. On May 15, 2015, Boston Properties Limited Partnership paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit. Boston Properties, Inc. The following table reflects the activity of the noncontrolling interests—redeemable preferred units of Boston Properties, Inc. for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ 110,876 Net income 6,046 Distributions (6,046 ) Redemption of redeemable preferred units (Series Four Preferred Units) (43,070 ) Conversion of redeemable preferred units (Series Two Preferred Units) to common units (16,494 ) Balance at December 31, 2013 51,312 Net income 1,023 Distributions (1,023 ) Redemption of redeemable preferred units (Series Four Preferred Units) (17,373 ) Conversion of redeemable preferred units (Series Two Preferred Units) to common units (33,306 ) Balance at December 31, 2014 633 Net income 6 Distributions (6 ) Redemption of redeemable preferred units (Series Four Preferred Units) (633 ) Balance at December 31, 2015 $ — Boston Properties Limited Partnership The following table reflects the activity of the noncontrolling interests—redeemable preferred units of Boston Properties Limited Partnership for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ 199,378 Net income 6,046 Distributions (6,046 ) Redemption of redeemable preferred units (Series Four Preferred Units) (43,070 ) Reallocation of partnership interest (1) (50,562 ) Balance at December 31, 2013 105,746 Net income 1,023 Distributions (1,023 ) Redemption of redeemable preferred units (Series Four Preferred Units) (17,373 ) Reallocation of partnership interest (1) (87,740 ) Balance at December 31, 2014 633 Net income 6 Distributions (6 ) Redemption of redeemable preferred units (Series Four Preferred Units) (633 ) Balance at December 31, 2015 $ — _____________ (1) Includes the conversion of 666,116 and 329,881 Series Two Preferred Units into 874,168 and 432,914 OP Units during the years ended December 31, 2014 and 2013 , respectively. 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 50% interest in the joint venture. The Company contributed cash totaling approximately $87.0 million for its 50% interest, which cash was distributed to the joint venture partner. Pursuant to the joint venture agreement (i) the Company had rights to acquire the partner’s nominal 50% interest and (ii) the partner had 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 were to expire on January 31, 2016. The Company was consolidating this joint venture due to the Company’s right to acquire the partner’s nominal 50% interest. The Company 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 was accreting 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 was recording the accretion after the allocation of net income and distributions of cash flow to the noncontrolling interest account balance. On August 6, 2015, the parties amended the joint venture agreement to require the Company to acquire its partner’s 50% interest on September 15, 2015 for approximately $100.9 million in cash. On September 15, 2015, the Company acquired its partner’s 50% interest in the consolidated entity that owns Fountain Square located in Reston Town Center in Reston, Virginia for cash of approximately $100.9 million plus working capital and closing prorations and the partner’s share of assumed mortgage indebtedness totaling approximately $105.6 million . 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 years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ 97,558 Net loss (1,839 ) Distributions (4,585 ) Adjustment to reflect redeemable interest at redemption value 8,475 Balance at December 31, 2013 99,609 Net loss (603 ) Distributions (6,000 ) Adjustment to reflect redeemable interest at redemption value 11,686 Balance at December 31, 2014 104,692 Net loss (7 ) Distributions (2,900 ) Adjustment to reflect redeemable interest at redemption value 5,128 Acquisition of interest (106,913 ) Balance at December 31, 2015 $ — Noncontrolling Interest—Common Units During the years ended December 31, 2015 and 2014 , 424,236 and 80,246 OP Units, respectively, were presented by the holders for redemption (including 0 and 3,734 OP Units, respectively, issued upon conversion of Series Two Preferred Units and 65,192 and 67,857 OP Units, respectively, issued upon conversion of LTIP Units) and were redeemed by Boston Properties, Inc. in exchange for an equal number of shares of Common Stock. At December 31, 2015 , the Company had outstanding 309,818 2013 MYLTIP Units, 476,320 2014 MYLTIP Units and 368,415 2015 MYLTIP Units (See Note 17 ). Prior to the applicable measurement date (February 4, 2016 for 2013 MYLTIP Units, February 3, 2017 for 2014 MYLTIP Units and February 4, 2018 for 2015 MYLTIP Units), holders of 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 MYLTIP Units, both vested and unvested, that 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 31, 2014, the measurement period for the Company’s 2011 OPP Unit awards expired and Boston Properties, Inc.'s TSR was not sufficient for employees to earn and therefore become eligible to vest in any of the 2011 OPP Unit awards. As a result, the Company accelerated the then remaining unrecognized compensation expense totaling approximately $1.2 million during the year ended December 31, 2014. Accordingly, all 2011 OPP Unit awards were automatically forfeited. On February 6, 2015, the measurement period for the Company’s 2012 OPP Unit awards ended and Boston Properties, Inc.'s TSR performance was sufficient for employees to earn and therefore become eligible to vest in a portion of the 2012 OPP Unit awards. The final outperformance pool was determined to be approximately $32.1 million , or approximately 80% of the total maximum outperformance pool of $40.0 million . As a result, 174,549 2012 OPP Units were automatically forfeited. On January 28, 2015, Boston Properties Limited Partnership paid a special cash distribution on the OP Units and LTIP Units in the amount of $4.50 per unit, a regular quarterly cash distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a regular quarterly distribution on the 2012 OPP Units, 2013 MYLTIP Units and 2014 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on December 31, 2014. The special cash distribution was in addition to the regular quarterly distribution on the OP Units and LTIP Units. Unless and until they are earned, holders of OPP Units and MYLTIP Units are not entitled to receive any special distributions. On April 30, 2015, Boston Properties Limited Partnership paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, a distribution on the 2012 OPP Units in the amount of $0.416 per unit (representing a blended rate for periods prior to and after February 6, 2015, which was the valuation date for the 2012 Outperformance Plan), and a distribution on the 2013 MYLTIP Units, 2014 MYLTIP Units and 2015 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on March 31, 2015. On July 31, 2015, Boston Properties Limited Partnership paid a distribution on the OP Units and LTIP Units (including the 2012 OPP Units) in the amount of $0.65 per unit and a distribution on the 2013 MYLTIP Units, 2014 MYLTIP Units and 2015 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on June 30, 2015. On October 30, 2015, Boston Properties Limited Partnership paid a distribution on the OP Units and LTIP Units (including the 2012 OPP Units) in the amount of $0.65 per unit and a distribution on the 2013 MYLTIP Units, 2014 MYLTIP Units and 2015 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on September 30, 2015. On December 17, 2015, Boston Properties, Inc., as general partner of Boston Properties Limited Partnership, declared a special cash distribution on the OP Units and LTIP Units (including the 2012 OPP Units) in the amount of $1.25 per unit payable on January 28, 2016 to unitholders of record as of the close of business on December 31, 2015. The special cash distribution was in addition to the regular quarterly distribution on the OP Units and LTIP Units (including the 2012 OPP Units) of $0.65 per unit and the distribution on the 2013 MYLTIP Units, 2014 MYLTIP Units and 2015 MYLTIP Units in the amount of $0.065 per unit, in each case payable on January 28, 2016 to unitholders of record as of the close of business on December 31, 2015. A holder of an OP Unit may present such OP Unit to Boston Properties Limited 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, Boston Properties Limited Partnership must redeem such OP Unit for cash equal to the then value of a share of common stock of Boston Properties, Inc. Boston Properties, Inc. 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 Boston Properties, Inc. and including LTIP Units assuming that all conditions had been met for the conversion thereof) had all of such units been redeemed at December 31, 2015 was approximately $2.3 billion based on the closing price of Boston Properties, Inc.’s common stock of $127.54 per share on December 31, 2015 . Boston Properties Limited Partnership The following table reflects the activity of noncontrolling interests—redeemable common units of Boston Properties Limited Partnership for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ 1,836,522 Contributions 26,398 Net income 84,236 Distributions (83,448 ) Conversion of redeemable partnership units (30,291 ) Unearned compensation 1,472 Other comprehensive income 252 Adjustment to reflect redeemable partnership units at redemption value (124,923 ) Balance at December 31, 2013 1,710,218 Contributions 23,990 Net income 50,862 Distributions (126,948 ) Conversion of redeemable partnership units (2,700 ) Unearned compensation (2,813 ) Other comprehensive income 256 Adjustment to reflect redeemable partnership units at redemption value 657,181 Balance at December 31, 2014 2,310,046 Contributions 39,030 Net income 66,951 Distributions (69,447 ) Conversion of redeemable partnership units (14,343 ) Unearned compensation (4,579 ) Other comprehensive loss (554 ) Adjustment to reflect redeemable partnership units at redemption value (40,415 ) Balance at December 31, 2015 $ 2,286,689 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 $1.6 billion at December 31, 2015 and December 31, 2014 , are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets. On May 31, 2013, the Company’s two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) in New York City) transferred all of their interests in the joint venture to third parties. In connection with the transfer, the Company and its new joint venture partners modified the Company’s relative decision making authority and consent rights with respect to the joint venture’s assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that the Company now accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting. Upon consolidation, the Company recognized the new joint venture partners’ aggregate 40% equity interest at its aggregate fair value of approximately $480.9 million within Noncontrolling Interests-Property Partnerships on the accompanying Consolidated Balance Sheets. On October 9, 2013, the Company completed the sale of a 45% ownership interest in its Times Square Tower property for a gross sale price of $684.0 million in cash. Net cash proceeds totaled approximately $673.1 million , after the payment of transaction costs. In connection with the sale, the Company formed a limited liability company with the buyer and will provide customary property management and leasing services to the joint venture. Times Square Tower is an approximately 1,246,000 net rentable square foot Class A office tower located in New York City. The transaction did not qualify as a sale of real estate for financial reporting purposes because the Company effectively continues to control the property and thus will continue to account for the entity on a consolidated basis in its financial statements. The Company has accounted for the transaction as an equity transaction and has recognized noncontrolling interest in its consolidated balance sheets totaling approximately $243.5 million , which is equal to 45% of the carrying value of the total equity of the property immediately prior to the transaction. The difference between the net cash proceeds received and the noncontrolling interest recognized, which was approximately $429.6 million , has not been reflected as a gain on sale of real estate in the Company’s consolidated statements of operations and has instead been reflected as an increase to Additional Paid-in Capital and Partners' Capital in Boston Properties, Inc.’s and Boston Properties Limited Partnership's Consolidated Balance Sheets, respectively. On October 30, 2014, the Company completed the sale of a 45% interest in each of 601 Lexington Avenue in New York City and Atlantic Wharf Office Building and 100 Federal Street in Boston for an aggregate gross sale price of approximately $1.827 billion in cash, less the partner’s pro rata share of the indebtedness collateralized by 601 Lexington Avenue. Net cash proceeds totaled approximately $1.497 billion , after the payment of transaction costs. In connection with the sale, the Company formed a limited liability company for each property with the buyer and will provide customary property management and leasing services to the joint ventures. 601 Lexington Avenue is a 1,669,000 square foot Class A office complex located in Midtown Manhattan. The property consists of a 59 -story tower as well as a six -story low-rise office and retail building. The property is subject to existing mortgage indebtedness of approximately $712.9 million . The Atlantic Wharf Office Building is a 791,000 square foot Class A office tower located on Boston's Waterfront. 100 Federal Street is a 1,323,000 square foot Class A office tower located in Boston’s Financial District. The transaction did not qualify as a sale of real estate for financial reporting purposes as the Company continues to effectively control these properties and thus will continue to account for the properties on a consolidated basis in its financial statements. The Company has accounted for the transaction as an equity transaction and has recognized noncontrolling interest in its consolidated balance sheets totaling approximately $849.0 million , which is equal to 45% of the aggregate carrying value of the total equity of the properties immediately prior to the transaction. The difference between the net cash proceeds received and the noncontrolling interest recognized, which was approximately $648.4 million , has not been reflected as a gain on sale of real estate in the Company's consolidated statements of operations and has instead been reflected as an increase in Additional Paid-in Capital in the Company’s Consolidated Balance Sheets. On September 18, 2015, a consolidated entity in which the Company has a 50% interest completed the sale of its 505 9th Street, N.W. property located in Washington, DC for approximately $318.0 million , including the assumption by the buyer of approximately $117.0 million of mortgage indebtedness (See Note 6 ). 505 9th Street, N.W. is an approximately 322,000 net rentable square foot Class A office building. Net cash proceeds totaled approximately $194.6 million , of which the partners’ share was approximately $97.3 million . The Company recognized a gain on sale of real estate totaling approximately $199.5 million and $199.7 million for Boston Properties, Inc. and Boston Properties Limited Partnership, respectively, of which approximately $101.1 million was allocated to the outside partners and is included within Noncontrolling Interests in Property Partnerships in the Company’s Consolidated Statements of Operations (See Note 3 ). On December 10, 2015, the consolidated entity was dissolved and the Company reclassified the remaining noncontrolling interest balance totaling approximately $4.1 million to Accounts Payable and Accrued Expenses on the Consolidated Balances Sheets. The following table reflects the activity of the noncontrolling interests—property partnerships for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ (1,964 ) Fair value of capital recorded upon consolidation 480,861 Capital contributions 257,564 Net loss (5,290 ) Distributions (5,039 ) Balance at December 31, 2013 726,132 Capital contributions 887,975 Net income 19,478 Distributions (31,118 ) Balance at December 31, 2014 1,602,467 Capital contributions 3,758 Dissolution (4,082 ) Net income 144,734 Accumulated other comprehensive loss (2,428 ) Distributions (170,049 ) Balance at December 31, 2015 $ 1,574,400

Stockholders' Equity _ Partners

Stockholders' Equity / Partners' Capital	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Stockholders' Equity	12. Stockholders’ Equity / Partners’ Capital Boston Properties, Inc. As of December 31, 2015 , Boston Properties, Inc. had 153,579,966 shares of Common Stock outstanding. On June 3, 2014, Boston Properties, Inc. established an “at the market” (ATM) stock offering program through which it may sell from time to time up to an aggregate of $600.0 million of its common stock through sales agents over a three -year period. The Company intends to use the net proceeds from any offering for general business purposes, which may include investment opportunities and debt reduction. No shares of Common Stock have been issued under this ATM stock offering program. During the years ended December 31, 2015 and 2014, Boston Properties, Inc. issued 11,447 and 21,459 shares of Common Stock upon the exercise of options to purchase Common Stock by certain employees. During the years ended December 31, 2015 and 2014 , Boston Properties, Inc. issued 424,236 and 80,246 shares of Common Stock, respectively, in connection with the redemption of an equal number of OP Units. The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per unit for the periods presented: Record Date Payment Date Dividend (Per Share) Distribution (Per Unit) December 31, 2015 January 28, 2016 $1.90 (1) $1.90 (1) September 30, 2015 October 30, 2015 0.65 0.65 June 30, 2015 July 31, 2015 0.65 0.65 March 31, 2015 April 30, 2015 0.65 0.65 December 31, 2014 January 28, 2015 5.15 (2) 5.15 (2) _______________ (1) Includes a special dividend/distribution of $1.25 per share/common unit. (2) Includes a special dividend/distribution of $4.50 per share/common unit. Preferred Stock As of December 31, 2015 , Boston Properties, Inc. had 80,000 shares ( 8,000,000 depositary shares each representing 1/100th of a share) outstanding of its 5.25% Series B Cumulative Redeemable Preferred Stock with a liquidation preference of $2,500.00 per share ( $25.00 per depositary share). Boston Properties, Inc. contributed the net proceeds of the offering to Boston Properties Limited Partnership in exchange for 80,000 Series B Preferred Units having terms and preferences generally mirroring those of the Series B Preferred Stock. Boston Properties, Inc. pays cumulative cash dividends on the Series B Preferred Stock at a rate of 5.25% per annum of the $2,500.00 liquidation preference per share. Boston Properties, Inc. may not redeem the Series B Preferred Stock prior to March 27, 2018, except in certain circumstances relating to the preservation of Boston Properties, Inc.’s REIT status. On or after March 27, 2018, Boston Properties, Inc., at its option, may redeem the Series B Preferred Stock for a cash redemption price of $2,500.00 per share ( $25.00 per depositary share), plus all accrued and unpaid dividends. The Series B Preferred Stock is not redeemable by the holders, has no maturity date and is not convertible into any other security of Boston Properties, Inc. or its affiliates. The following table presents Boston Properties Inc.’s dividends per share on its outstanding Series B Preferred Stock: Record Date Payment Date Dividend (Per Share) February 5, 2016 February 16, 2016 $32.8125 November 5, 2015 November 16, 2015 32.8125 August 5, 2015 August 17, 2015 32.8125 May 5, 2015 May 15, 2015 32.8125 February 5, 2015 February 17, 2015 32.8125 Boston Properties Limited Partnership The following table presents the changes in the issued and outstanding partners’ capital units since January 1, 2013: General Partner Units Limited Partner Units Total Partners’ Outstanding at December 31, 2012 1,689,580 149,911,629 151,601,209 Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan 50 6,392 6,442 Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net 207 26,686 26,893 Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units 7,158 922,283 929,441 Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs 3,227 415,889 419,116 Outstanding at December 31, 2013 1,700,222 151,282,879 152,983,101 Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan 555 6,409 6,964 Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net 3,476 40,158 43,634 Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units 6,391 73,855 80,246 Outstanding at December 31, 2014 1,710,644 151,403,301 153,113,945 Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan 59 6,140 6,199 Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net 340 35,246 35,586 Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units 4,049 420,187 424,236 Outstanding at December 31, 2015 1,715,092 151,864,874 153,579,966 As of December 31, 2015 , Boston Properties, Inc. owned 1,715,092 general partnership units and 151,864,874 limited partnership units. The following table reflects the activity of the Series B Preferred Units for the years ended December 31, 2015 , 2014 and 2013 (in thousands), which activity is included within Boston Properties Limited Partnership’s Consolidated Statements of Partners’ Capital: Balance at December 31, 2012 $ — Issuance of Series B Preferred Units 193,623 Net income 8,057 Distributions (8,057 ) Balance at December 31, 2013 193,623 Net income 10,500 Distributions (10,500 ) Balance at December 31, 2014 193,623 Net income 10,500 Distributions (10,500 ) Balance at December 31, 2015 $ 193,623

Future Minimum Rents

Future Minimum Rents	12 Months Ended
	Dec. 31, 2015
Future Minimum Rents [Abstract]
Future Minimum Rents [Text Block]	13. Future Minimum Rents The properties are leased to tenants under net operating leases with initial term expiration dates ranging from 2016 to 2046 . The future contractual minimum lease payments to be received (excluding operating expense reimbursements) by the Company as of December 31, 2015 , under non-cancelable operating leases which expire on various dates through 2046 , are as follows: Years Ending December 31, (in thousands) 2016 $ 1,854,538 2017 1,815,632 2018 1,733,703 2019 1,666,019 2020 1,500,843 Thereafter 8,667,163 No single tenant represented more than 10.0% of the Company’s total rental revenue for the years ended December 31, 2015 , 2014 and 2013 .

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	14. 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, 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 income, general and administrative expenses, transaction costs, impairment loss, interest expense, depreciation and amortization expense, gains (losses) from investments in securities, gains (losses) from early extinguishments of debt, income from unconsolidated joint ventures, gains on consolidation of joint ventures, discontinued operations, gains on sales of real estate, noncontrolling interests and preferred dividends/distributions 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. The Company’s management also uses Net Operating Income to evaluate regional property level performance and to make decisions about resource allocations. Further, the Company believes Net Operating Income is useful to investors as a performance measure because, when compared across periods, Net Operating Income reflects the impact on operations from trends in occupancy rates, rental rates, operating costs and acquisition and development activity on an unleveraged basis, providing perspectives not immediately apparent from net income attributable to Boston Properties, Inc. common shareholders and net income attributable to Boston Properties Limited Partnership common unitholders. On May 31, 2013, the Company’s two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties (See Note 3 ). Effective as of May 31, 2013, the Company accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting. Upon consolidation, the operations for this building are included in the New York region. Information by geographic area and property type (dollars in thousands): For the year ended December 31, 2015 : Boston New York San Francisco Washington, DC Total Rental Revenue: Class A Office $ 692,419 $ 1,000,030 $ 280,005 $ 372,721 $ 2,345,175 Office/Technical 23,827 — 22,429 11,907 58,163 Residential 4,801 — — 14,082 18,883 Hotel 46,046 — — — 46,046 Total 767,093 1,000,030 302,434 398,710 2,468,267 % of Grand Totals 31.08 % 40.52 % 12.25 % 16.15 % 100.00 % Rental Expenses: Class A Office 280,307 346,897 94,268 127,291 848,763 Office/Technical 7,034 — 3,938 4,290 15,262 Residential 2,006 — — 6,221 8,227 Hotel 32,084 — — — 32,084 Total 321,431 346,897 98,206 137,802 904,336 % of Grand Totals 35.54 % 38.36 % 10.86 % 15.24 % 100.00 % Net operating income $ 445,662 $ 653,133 $ 204,228 $ 260,908 $ 1,563,931 % of Grand Totals 28.50 % 41.76 % 13.06 % 16.68 % 100.00 % For the year ended December 31, 2014 : Boston New York San Francisco Washington, DC Total Rental Revenue: Class A Office $ 692,116 $ 928,692 $ 237,381 $ 381,930 $ 2,240,119 Office/Technical 23,801 — 23,840 14,344 61,985 Residential 4,528 — — 21,665 26,193 Hotel 43,385 — — — 43,385 Total 763,830 928,692 261,221 417,939 2,371,682 % of Grand Totals 32.21 % 39.16 % 11.01 % 17.62 % 100.00 % Rental Expenses: Class A Office 270,947 315,330 85,178 131,447 802,902 Office/Technical 7,173 — 4,955 4,338 16,466 Residential 1,957 — — 13,965 15,922 Hotel 29,236 — — — 29,236 Total 309,313 315,330 90,133 149,750 864,526 % of Grand Totals 35.78 % 36.47 % 10.43 % 17.32 % 100.00 % Net operating income $ 454,517 $ 613,362 $ 171,088 $ 268,189 $ 1,507,156 % of Grand Totals 30.16 % 40.70 % 11.35 % 17.79 % 100.00 % For the year ended December 31, 2013 : Boston New York San Francisco Washington, DC Total Rental Revenue: Class A Office $ 665,991 $ 725,566 $ 214,755 $ 381,359 $ 1,987,671 Office/Technical 22,617 — 17,259 15,649 55,525 Residential 4,395 — — 17,923 22,318 Hotel 40,330 — — — 40,330 Total 733,333 725,566 232,014 414,931 2,105,844 % of Grand Totals 34.82 % 34.46 % 11.02 % 19.70 % 100.00 % Rental Expenses: Class A Office 259,997 251,640 77,905 126,507 716,049 Office/Technical 6,879 — 3,708 4,190 14,777 Residential 1,823 — — 10,307 12,130 Hotel 28,447 — — — 28,447 Total 297,146 251,640 81,613 141,004 771,403 % of Grand Totals 38.52 % 32.62 % 10.58 % 18.28 % 100.00 % Net operating income $ 436,187 $ 473,926 $ 150,401 $ 273,927 $ 1,334,441 % of Grand Totals 32.69 % 35.51 % 11.27 % 20.53 % 100.00 % Boston Properties, Inc. The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties, Inc. common shareholders (in thousands): Year ended December 31, 2015 2014 2013 Net Operating Income $ 1,563,931 $ 1,507,156 $ 1,334,441 Add: Development and management services income 22,554 25,316 29,695 Income from unconsolidated joint ventures 22,770 12,769 75,074 Gains on consolidation of joint ventures — — 385,991 Interest and other income 6,777 8,765 8,310 Gains (losses) from investments in securities (653 ) 1,038 2,911 Gains (losses) from early extinguishments of debt (22,040 ) (10,633 ) 122 Income from discontinued operations — — 8,022 Gains on sales of real estate from discontinued operations — — 112,829 Gain on forgiveness of debt from discontinued operations — — 20,182 Gains on sales of real estate 375,895 168,039 — Less: General and administrative expense 96,319 98,937 115,329 Transaction costs 1,259 3,140 1,744 Depreciation and amortization expense 639,542 628,573 560,637 Interest expense 432,196 455,743 446,880 Impairment loss — — 8,306 Impairment loss from discontinued operations — — 3,241 Noncontrolling interest in property partnerships 149,855 30,561 1,347 Noncontrolling interest—redeemable preferred units of the Operating Partnership 6 1,023 6,046 Noncontrolling interest—common units of the Operating Partnership 66,951 50,862 70,085 Noncontrolling interest in discontinued operations—common units of the Operating Partnership — — 14,151 Preferred dividends 10,500 10,500 8,057 Net income attributable to Boston Properties, Inc. common shareholders $ 572,606 $ 433,111 $ 741,754 Boston Properties Limited Partnership The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership common unitholders (in thousands): Year ended December 31, 2015 2014 2013 Net Operating Income $ 1,563,931 $ 1,507,156 $ 1,334,441 Add: Development and management services income 22,554 25,316 29,695 Income from unconsolidated joint ventures 22,770 12,769 75,074 Gains on consolidation of joint ventures — — 385,991 Interest and other income 6,777 8,765 8,310 Gains (losses) from investments in securities (653 ) 1,038 2,911 Gains (losses) from early extinguishments of debt (22,040 ) (10,633 ) 122 Income from discontinued operations — — 8,022 Gains on sales of real estate from discontinued operations — — 115,459 Gain on forgiveness of debt from discontinued operations — — 20,736 Gains on sales of real estate 377,093 174,686 — Less: General and administrative expense 96,319 98,937 115,329 Transaction costs 1,259 3,140 1,744 Depreciation and amortization expense 631,549 620,064 552,589 Interest expense 432,196 455,743 446,880 Impairment loss — — 4,401 Impairment loss from discontinued operations — — 2,852 Noncontrolling interest in property partnerships 149,855 30,561 1,347 Noncontrolling interest—redeemable preferred units 6 1,023 6,046 Preferred distributions 10,500 10,500 8,057 Net income attributable to Boston Properties Limited Partnership common unitholders $ 648,748 $ 499,129 $ 841,516

Earnings Per Share _ Common Uni

Earnings Per Share / Common Unit	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share	15. Earnings Per Share / Common Unit Boston Properties, Inc. The following table provides a reconciliation of both the net income attributable to Boston Properties, Inc. common shareholders 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. common shareholders by the weighted-average number of common shares outstanding during the period. The terms of the Series Two Preferred Units enabled the holders to obtain OP Units of Boston Properties Limited Partnership, and therefore Common Stock of Boston Properties, Inc., and as a result these are considered participating securities. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of Boston Properties, Inc., LTIP Units, OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic EPS of Boston Properties, Inc. using the two-class method. Participating securities are included in the computation of diluted EPS of Boston Properties, Inc. using the if-converted method if the impact is dilutive. Because the OPP Units and MYLTIP Units require Boston Properties, Inc. to outperform absolute and relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, Boston Properties, Inc. excludes such units from the diluted EPS calculation. Other potentially dilutive common shares, including stock options, restricted stock and other securities of Boston Properties Limited Partnership that are exchangeable for Boston Properties, Inc.’s Common Stock, and the related impact on earnings, are considered when calculating diluted EPS. For the Year Ended December 31, 2015 Income (Numerator) Shares (Denominator) Per Share Amount (in thousands, except for per share amounts) Basic Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 572,606 153,471 $ 3.73 Effect of Dilutive Securities: Stock Based Compensation — 373 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 572,606 153,844 $ 3.72 For the Year Ended December 31, 2014 Income (Numerator) Shares (Denominator) Per Share Amount (in thousands, except for per share amounts) Basic Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 433,111 153,089 $ 2.83 Effect of Dilutive Securities: Stock Based Compensation — 219 — Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 433,111 153,308 $ 2.83 For the Year Ended December 31, 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. $ 618,113 152,201 $ 4.06 Discontinued operations attributable to Boston Properties, Inc. 123,641 — 0.81 Allocation of undistributed earnings to participating securities (160 ) — — Net income attributable to Boston Properties, Inc. common shareholders $ 741,594 152,201 $ 4.87 Effect of Dilutive Securities: Stock Based Compensation and Exchangeable Senior Notes — 320 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 741,594 152,521 $ 4.86 Boston Properties Limited Partnership The following table provides a reconciliation of both the net income attributable to Boston Properties Limited Partnership common unitholders and the number of common units used in the computation of basic earnings per common unit, which is calculated by dividing net income attributable to Boston Properties Limited Partnership common unitholders by the weighted-average number of common units outstanding during the period. The terms of the Series Two Preferred Units enable the holders to obtain OP Units of Boston Properties Limited Partnership and as a result these are considered participating securities. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of Boston Properties, Inc. and Boston Properties Limited Partnership’s LTIP Units, OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic earnings per common unit using the two-class method. Participating securities are included in the computation of diluted earnings per common unit using the if-converted method if the impact is dilutive. Because the OPP Units and MYLTIP Units require Boston Properties, Inc. to outperform absolute and relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, Boston Properties Limited Partnership excludes such units from the diluted earnings per common unit calculation. Other potentially dilutive common units and the related impact on earnings are considered when calculating diluted earnings per common unit. Included in the number of units (the denominator) below are approximately 17,668,000 , 17,364,000 and 16,925,000 redeemable common units for the years ended December 31, 2015 , 2014 and 2013 , respectively. For the Year Ended December 31, 2015 Income (Numerator) Units (Denominator) Per Unit Amount (in thousands, except for per unit amounts) Basic Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 648,748 171,139 $ 3.79 Effect of Dilutive Securities: Stock Based Compensation — 373 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 648,748 171,512 $ 3.78 For the Year Ended December 31, 2014 Income (Numerator) Units (Denominator) Per Unit Amount (in thousands, except for per unit amounts) Basic Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 499,129 170,453 $ 2.93 Effect of Dilutive Securities: Stock Based Compensation — 219 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 499,129 170,672 $ 2.92 For the Year Ended December 31, 2013 Income (Numerator) Units (Denominator) Per Unit Amount (in thousands, except for per unit amounts) Basic Earnings: Income from continuing operations attributable to Boston Properties Limited Partnership $ 700,151 169,126 $ 4.14 Discontinued operations attributable to Boston Properties Limited Partnership 141,365 — 0.84 Allocation of undistributed earnings to participating securities (178 ) — (0.01 ) Net income attributable to Boston Properties Limited Partnership common unitholders $ 841,338 169,126 $ 4.97 Effect of Dilutive Securities: Stock Based Compensation and Exchangeable Senior Notes — 320 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 841,338 169,446 $ 4.97

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2015
Employee Benefit Plans [Abstract]
Compensation and Employee Benefit Plans [Text Block]	16. Employee Benefit Plans Effective January 1, 1985, the predecessor of the Company adopted a 401(k) Savings Plan (the “Plan”) for its employees. Under the Plan, as amended, employees, as defined, are eligible to participate in the Plan after they have completed three months of service. Upon formation, the Company adopted the Plan and the terms of the Plan. Under the Plan, as amended, the Company’s matching contribution equals 200% of the first 3% of participant’s eligible earnings contributed (utilizing earnings that are not in excess of an amount established by the IRS ( $265,000 , $260,000 and $255,000 in 2015 , 2014 and 2013 , respectively), indexed for inflation) with no vesting requirement. The Company’s aggregate matching contribution for the years ended December 31, 2015 , 2014 and 2013 was $3.7 million , $3.5 million and $3.4 million , respectively. The Plan also provides for supplemental retirement contributions to certain employees who had at least ten years of service on January 1, 2001, and who were 40 years of age or older as of January 1, 2001. The maximum supplemental retirement contribution will not exceed the annual limit on contributions established by the IRS. The Company will record an annual supplemental retirement credit for the benefit of each participant. The Company’s supplemental retirement contribution and credit for the years ended December 31, 2015 , 2014 and 2013 was $42,000 , $52,000 and $60,000 , respectively. The Company also maintains a deferred compensation plan that is designed to allow officers of Boston Properties, Inc. to defer a portion of their current income on a pre-tax basis and receive a tax-deferred return on these deferrals. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2015 and 2014 , the Company had maintained approximately $20.4 million and $19.5 million , respectively, in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the plan participants and earnings on the deferred compensation pursuant to investments elected by the plan participants. The Company’s liability as of December 31, 2015 and 2014 was $20.4 million and $19.5 million , respectively, which are included in the accompanying Consolidated Balance Sheets.

Stock Option and Incentive Plan

Stock Option and Incentive Plan	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option and Incentive Plan	17. Stock Option and Incentive Plan At Boston Properties, Inc.’s 2012 annual meeting of stockholders held on May 15, 2012, its stockholders approved the Boston Properties, Inc. 2012 Stock Option and Incentive Plan (the “2012 Plan”). The 2012 Plan replaced the 1997 Stock Option and Incentive Plan (the “1997 Plan”). The material terms of the 2012 Plan include, among other things: (1) the maximum number of shares of common stock reserved and available for issuance under the 2012 Plan is the sum of (i) 13,000,000 newly authorized shares, plus (ii) the number of shares available for grant under the 1997 Stock Plan immediately prior to the effective date of the 2012 Plan, plus (iii) any shares underlying grants under the 1997 Plan that are forfeited, canceled or terminated (other than by exercise) in the future; (2) “full-value” awards (i.e., awards other than stock options) are multiplied by a 2.32 conversion ratio to calculate the number of shares available under the 2012 Plan that are used for each full-value award, as opposed to a 1.0 conversion ratio for each stock option awarded under the 2012 Plan; (3) shares tendered or held back for taxes will not be added back to the reserved pool under the 2012 Plan; (4) stock options may not be re-priced without stockholder approval; and (5) the term of the 2012 Plan is for ten years from the date of stockholder approval. On January 21, 2015, Boston Properties, Inc.’s Compensation Committee approved the 2015 MYLTIP awards under its 2012 Plan to certain officers and employees of Boston Properties, Inc. The 2015 MYLTIP awards utilize TSR over a three -year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on Boston Properties, Inc.’s TSR relative to (i) the Cohen & Steers Realty Majors Portfolio Index ( 50% weight) and (ii) the NAREIT Office Index adjusted to exclude Boston Properties, Inc. ( 50% weight). Earned awards will range from $0 to a maximum of approximately $40.8 million depending on Boston Properties, Inc.’s TSR relative to the two indices, with three tiers (threshold: approximately $8.2 million ; target: approximately $16.3 million ; high: approximately $40.8 million ) and linear interpolation between tiers. Earned awards measured on the basis of relative TSR performance are subject to an absolute TSR component in the form of relatively simple modifiers that (A) reduce the level of earned awards in the event Boston Properties, Inc.’s annualized TSR is less than 0% and (B) cause some awards to be earned in the event Boston Properties, Inc.’s annualized TSR is more than 12% even though on a relative basis alone Boston Properties, Inc.’s TSR would not result in any earned awards. Earned awards (if any) will vest 50% on February 4, 2018 and 50% on February 4, 2019, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by Boston Properties, Inc. without cause, or 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, 2018, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2015 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 OP Units. Under the FASB’s ASC 718 “Compensation-Stock Compensation,” the 2015 MYLTIP awards have an aggregate value of approximately $15.7 million , which amount will generally be amortized into earnings over the four -year plan period under the graded vesting method. On February 6, 2015, the measurement period for the Company’s 2012 OPP Unit awards ended and Boston Properties, Inc.'s TSR performance was sufficient for employees to earn and therefore become eligible to vest in a portion of the 2012 OPP Unit awards. The final outperformance pool was determined to be approximately $32.1 million , or approximately 80% of the total maximum outperformance pool of $40.0 million . As a result, 174,549 2012 OPP Units were automatically forfeited. On March 11, 2013, Boston Properties, Inc. announced that Owen D. Thomas would succeed Mortimer B. Zuckerman as its 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 continued to serve as Executive Chairman for a transition period which was completed effective as of the close of business on December 31, 2014 and thereafter is continuing to serve as the non-executive Chairman of the Board of Boston Properties, Inc. In connection with succession planning, Boston Properties, Inc. and Mr. Zuckerman entered into a Transition Benefits Agreement. If Mr. Zuckerman remained employed by Boston Properties, Inc. through July 1, 2014, he was 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 vested one-third on each of March 10, 2013, October 1, 2013 and July 1, 2014. As a result, the Company recognized approximately $3.9 million and $13.8 million of compensation expense during the years ended December 31, 2014 and 2013, respectively. In addition, the agreement provided that if Mr. Zuckerman terminated his employment with Boston Properties, Inc. for any reason, voluntarily or involuntarily, he would become fully vested in any outstanding equity awards with time-based vesting. As a result, during the year ended December 31, 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. Boston Properties, Inc. issued 34,150 , 23,968 and 36,730 shares of restricted common stock and Boston Properties Limited Partnership issued 190,563 (including 85,962 LTIP Units issued on January 1, 2015 to Mortimer B. Zuckerman, non-executive Chairman of the Board of Boston Properties, Inc., pursuant to the Transition Benefits Agreement dated March 10, 2013), 127,094 and 184,733 LTIP Units to employees and non-employee directors under the 2012 Plan during the years ended December 31, 2015 , 2014 and 2013 , respectively. Boston Properties, Inc. did not issue any non-qualified stock options under the 2012 Plan during the years ended December 31, 2015 and 2014. Boston Properties, Inc. issued 252,220 non-qualified stock options under the 2012 Plan during the year ended December 31, 2013 . The amounts issued during 2013 include the amounts issued to Mr. Thomas pursuant to his employment agreement, as discussed above. Boston Properties Limited Partnership issued 318,926 2013 MYLTIP Units to employees under the 2012 Plan during the year ended December 31, 2013, including the amounts issued to Mr. Thomas pursuant to his employment agreement, as discussed above. Boston Properties Limited Partnership issued 485,459 2014 MYLTIP Units to employees under the 2012 Plan during the year ended December 31, 2014. Boston Properties Limited Partnership issued 375,000 2015 MYLTIP Units to employees under the 2012 Plan during the year ended December 31, 2015. Employees and directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit, OPP Unit and MYLTIP Unit. At the time of an award, LTIP Units do not have full economic parity with OP Units or Common Stock, but can achieve parity over time upon the occurrence of specified events in accordance with partnership tax rules. The aggregate value of the LTIP Units is included in noncontrolling interests in the Consolidated Balance Sheets. Grants of restricted stock and LTIP Units to employees vest in four equal annual installments. Restricted stock is measured at fair value on the date of grant based on the number of shares granted, as adjusted for forfeitures, and the closing price of Boston Properties, Inc.’s Common Stock on the date of grant as quoted on the New York Stock Exchange. Such value is recognized as an expense ratably over the corresponding employee service period. Non-qualified stock options, which are valued using the Black-Scholes option-pricing model, are recognized as an expense ratably over the corresponding employee service period. As the 2012 OPP Awards, 2013 MYLTIP Awards, 2014 MYLTIP Awards and 2015 MYLTIP Awards are subject to both a service condition and a market condition, the Company recognizes the compensation expense related to the 2012 OPP Awards, 2013 MYLTIP Awards, 2014 MYLTIP Awards and 2015 MYLTIP Awards under the graded vesting attribution method. Under the graded vesting attribution method, each portion of the award that vests at a different date is accounted for as a separate award and recognized over the period appropriate to that portion so that the compensation cost for each portion should be recognized in full by the time that portion vests. Dividends paid on both vested and unvested shares of restricted stock are charged directly to Dividends in Excess of Earnings in Boston Properties, Inc.’s Consolidated Balance Sheets and Partners’ Capital in Boston Properties Limited Partnership’s Consolidated Balance Sheets. Aggregate stock-based compensation expense associated with restricted stock, non-qualified stock options, LTIP Units, 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units and 2015 MYLTIP Units was approximately $26.9 million , $26.0 million and $43.9 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. For the years ended December 31, 2014 and 2013, stock-based compensation expense includes approximately $2.5 million and $21.5 million , respectively, consisting of the acceleration of the expense of Boston Properties, Inc.’s Executive Chairman’s stock-based compensation awards and the stock-based compensation awards associated with his transition benefits agreement related to Boston Properties, Inc.’s succession planning. At December 31, 2015 , there was $18.3 million of unrecognized compensation expense related to unvested restricted stock, LTIP Units and 2012 OPP Units and $17.8 million of unrecognized compensation expense related to unvested 2013 MYLTIP Units, 2014 MYLTIP Units and 2015 MYLTIP Units that is expected to be recognized over a weighted-average period of approximately 2.4 years . The shares of restricted stock were valued at approximately $4.8 million ( $140.88 per share weighted-average), $2.6 million ( $109.27 per share weighted-average) and $3.9 million ( $105.30 per share weighted-average) for the years ended December 31, 2015 , 2014 and 2013 , respectively. LTIP Units were valued using a Monte Carlo simulation method model in accordance with the provisions of ASC 718. LTIP Units issued during the years ended December 31, 2015 , 2014 and 2013 were valued at approximately $13.5 million (excluding the number issued to Mr. Zuckerman, as discussed above), $12.8 million and $17.8 million , respectively. The weighted-average per unit fair value of LTIP Unit grants in 2015 , 2014 and 2013 was $128.94 , $100.61 and $96.13 , respectively. The per unit fair value of each LTIP Unit granted in 2015 , 2014 and 2013 was estimated on the date of grant using the following assumptions; an expected life of 5.7 years , 5.7 years and 5.7 years , a risk-free interest rate of 1.47% , 1.84% and 1.03% and an expected price volatility of 26.0% , 27.0% and 26.0% , respectively. There were no non-qualified stock options granted during the years ended December 31, 2015 and 2014. The non-qualified stock options granted during the year ended December 31, 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 assumptions: an expected life of 6.0 years , a risk-free interest rate of 1.11% , an expected price volatility of 26.0% and an expected dividend yield of 3.0% . The exercise price of the options granted during the year ended December 31, 2013 was $105.10 , which was the closing price of Boston Properties, Inc.’s Common Stock on the date of grant. A summary of the status of Boston Properties, Inc.’s stock options as of December 31, 2015 , 2014 and 2013 and changes during the years then ended are presented below: Shares Weighted-Average Exercise Price Outstanding at December 31, 2012 294,527 $ 101.06 Granted 252,220 $ 104.50 Special dividend adjustment 12,076 $ 100.44 Outstanding at December 31, 2013 558,823 $ 100.43 Exercised (21,459 ) $ 97.04 Canceled (2,444 ) $ 103.57 Special dividend adjustment 18,392 $ 97.22 Outstanding at December 31, 2014 553,312 $ 97.21 Exercised (11,447 ) $ 92.50 Special dividend adjustment 5,264 $ 96.38 Outstanding at December 31, 2015 547,129 $ 96.38 The following table summarizes information about Boston Properties, Inc.’s stock options outstanding at December 31, 2015 : Options Outstanding Options Exercisable Number Outstanding at 12/31/15 Weighted-Average Remaining Contractual Life Exercise Price Number Exercisable at 12/31/15 Exercise Price 118,502 5.1 years $ 86.86 118,502 $ 86.86 54,282 7.3 years $ 95.69 27,141 $ 95.69 206,728 7.1 years $ 98.46 168,332 $ 98.46 167,617 6.1 years $ 100.77 151,396 $ 100.77 The total intrinsic value of the outstanding and exercisable stock options as of December 31, 2015 was approximately $14.6 million . In addition, Boston Properties, Inc. had 411,143 and 199,868 options exercisable at a weighted-average exercise price of $96.91 and $98.83 at December 31, 2014 and 2013, respectively. Boston Properties, Inc. adopted the 1999 Non-Qualified Employee Stock Purchase Plan (the “Stock Purchase Plan”) to encourage the ownership of Common Stock by eligible employees. The Stock Purchase Plan became effective on January 1, 1999 with an aggregate maximum of 250,000 shares of Common Stock available for issuance. The Stock Purchase Plan provides for eligible employees to purchase on the business day immediately following the end of the biannual purchase periods (i.e., January 1-June 30 and July 1-December 31) shares of Common Stock at a purchase price equal to 85% of the average closing prices of the Common Stock during the last ten business days of the purchase period. Boston Properties, Inc. issued 6,199 , 6,964 and 6,442 shares with the weighted average purchase price equal to $108.73 per share, $93.37 per share and $89.65 per share under the Stock Purchase Plan during the years ended December 31, 2015 , 2014 and 2013 , respectively.

Related Party Transactions

Related Party Transactions	180 Months Ended
	Dec. 31, 2015
Related Party Transaction [Line Items]
Related Party Transactions Disclosure [Text Block]	18. Related Party Transactions Prior to joining Boston Properties, Inc. effective January 2, 2014, Mr. John F. Powers provided commercial real estate brokerage services to the Company, on behalf of his prior employer, CBRE, in connection with certain leasing transactions. Mr. Powers received approximately $616,000 , $1,214,000 and $592,000 during the years ended December 31, 2015, 2014 and 2013, respectively, in connection with these transactions. Mr. John F. Powers is an Executive Vice President of Boston Properties, Inc. and the Regional Manager of its New York office. A firm controlled by Mr. Raymond A. Ritchey’s brother was paid aggregate leasing commissions of approximately $384,000 , $674,000 and $868,000 for the years ended December 31, 2015 , 2014 and 2013 , respectively, related to certain exclusive leasing arrangements for certain Northern Virginia properties. Mr. Ritchey is a Senior Executive Vice President of Boston Properties, Inc. In accordance with Boston Properties, Inc.’s 2012 Plan, and as approved by its Board of Directors, six non-employee directors made an election to receive deferred stock units in lieu of cash fees for 2015 . The deferred stock units will be settled in shares of common stock upon the cessation of such director’s service on the Board of Directors of Boston Properties, Inc. As a result of these elections, the aggregate cash fees otherwise payable to a non-employee director during a fiscal quarter are converted into a number of deferred stock units equal to the aggregate cash fees divided by the last reported sales price of a share of Boston Properties, Inc.’s common stock on the last trading of the applicable fiscal quarter. The deferred stock units are also credited with dividend equivalents as dividends are paid by Boston Properties, Inc. On May 20, 2014, in connection with the cessation of a director’s service on the Board of Directors of Boston Properties, Inc., Boston Properties, Inc. issued 7,542 shares of common stock in settlement of the director’s outstanding deferred stock units. At December 31, 2015 and 2014 , Boston Properties, Inc. had outstanding 93,044 and 84,435 deferred stock units, respectively.

Selected Interim Financial Info

Selected Interim Financial Information (unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	19. Selected Interim Financial Information (unaudited) Boston Properties, Inc. The tables below reflect Boston Properties, Inc.’s selected quarterly information for the years ended December 31, 2015 and 2014 . 2015 Quarter Ended March 31, June 30, September 30, December 31, (in thousands, except for per share amounts) Total revenue $ 618,476 $ 618,221 $ 629,884 $ 624,240 Income before gains on sales of real estate $ 114,086 $ 100,739 $ 123,792 $ 85,406 Net income attributable to Boston Properties, Inc. common shareholders $ 171,182 $ 79,460 $ 184,082 $ 137,851 Income attributable to Boston Properties, Inc. per share—basic $ 1.12 $ 0.52 $ 1.20 $ 0.90 Income attributable to Boston Properties, Inc. per share—diluted $ 1.11 $ 0.52 $ 1.20 $ 0.90 2014 Quarter Ended March 31, June 30, September 30, December 31, (in thousands, except for per share amounts) Total revenue $ 574,694 $ 589,794 $ 618,803 $ 613,707 Income before gains on sales of real estate $ 67,756 $ 95,901 $ 109,038 $ 85,323 Net income attributable to Boston Properties, Inc. common shareholders $ 54,034 $ 76,527 $ 127,724 $ 174,510 Income attributable to Boston Properties, Inc. per share—basic $ 0.35 $ 0.50 $ 0.83 $ 1.14 Income attributable to Boston Properties, Inc. per share—diluted $ 0.35 $ 0.50 $ 0.83 $ 1.14 Boston Properties Limited Partnership The tables below reflect Boston Properties Limited Partnership’s selected quarterly information for the years ended December 31, 2015 and 2014 . 2015 Quarter Ended March 31, June 30, September 30, December 31, (in thousands, except for per unit amounts) Total revenue $ 618,476 $ 618,221 $ 629,884 $ 624,240 Income before gains on sales of real estate $ 116,085 $ 102,737 $ 125,790 $ 87,404 Net income attributable to Boston Properties Limited Partnership common unitholders $ 193,369 $ 90,852 $ 207,626 $ 156,901 Income attributable to Boston Properties Limited Partnership per unit—basic $ 1.13 $ 0.53 $ 1.21 $ 0.92 Income attributable to Boston Properties Limited Partnership per unit—diluted $ 1.12 $ 0.53 $ 1.21 $ 0.92 2014 Quarter Ended March 31, June 30, September 30, December 31, (in thousands, except for per unit amounts) Total revenue $ 574,694 $ 589,794 $ 618,803 $ 613,707 Income before gains on sales of real estate $ 69,781 $ 97,927 $ 111,066 $ 87,753 Net income attributable to Boston Properties Limited Partnership common unitholders $ 62,219 $ 87,436 $ 144,715 $ 204,759 Income attributable to Boston Properties Limited Partnership per unit—basic $ 0.37 $ 0.51 $ 0.85 $ 1.20 Income attributable to Boston Properties Limited Partnership per unit—diluted $ 0.37 $ 0.51 $ 0.85 $ 1.20

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	20. Subsequent Events On January 4, 2016 and January 6, 2016, 767 Fifth Partners LLC, the consolidated entity in which the Company has a 60% interest and owns 767 Fifth Avenue (the General Motors Building) in New York City, entered into two forward-starting interest rate swap contracts which fix the 10 -year swap rate at an average of 2.403% per annum on notional amounts aggregating $50.0 million . The interest rate swap contracts were entered into in advance of a financing with a target commencement date in June 2017 and maturity in June 2027 (See Note 7 ). On January 20, 2016, Boston Properties Limited Partnership completed a public offering of $1.0 billion in aggregate principal amount of its 3.650% senior unsecured notes due 2026. The notes were priced at 99.708% of the principal amount to yield an effective rate (including financing fees) of 3.766% to maturity. The notes will mature on February 1, 2026, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $988.9 million after deducting underwriting discounts and estimated transaction expenses. On January 25, 2016, Boston Properties, Inc.’s Compensation Committee approved the 2016 Multi-Year, Long-Term Incentive Program (the “2016 MYLTIP”) awards under Boston Properties, Inc.’s 2012 Plan to certain officers and employees of Boston Properties, Inc. The 2016 MYLTIP awards utilize Boston Properties, Inc.’s total stockholder return (“TSR”) over a three -year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on Boston Properties, Inc.’s TSR relative to (i) the Cohen & Steers Realty Majors Portfolio Index ( 50% weight) and (ii) the NAREIT Office Index adjusted to include Vornado Realty Trust and exclude Boston Properties, Inc. ( 50% weight). Earned awards will range from zero to a maximum of approximately $49.3 million depending on Boston Properties, Inc.’s TSR relative to the two indices, with three tiers (threshold: approximately $9.9 million ; target: approximately $19.7 million ; high: approximately $49.3 million ) and linear interpolation between tiers. Earned awards measured on the basis of relative TSR performance are subject to an absolute TSR component in the form of relatively simple modifiers that (A) reduce the level of earned awards in the event Boston Properties, Inc.’s annualized TSR is less than 0% and (B) cause some awards to be earned in the event Boston Properties, Inc.’s annualized TSR is more than 12% even though on a relative basis alone Boston Properties, Inc.’s TSR would not result in any earned awards. Earned awards (if any) will vest 50% on February 9, 2019 and 50% on February 9, 2020, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by Boston Properties, Inc. without cause, or termination of employment by the award recipient for good reason, death, disability or retirement. If there is a change of control prior to February 9, 2019, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2016 MYLTIP awards are in the form of LTIP Units issued on the grant date which (i) are subject to forfeiture to the extent awards are not earned and (ii) prior to the performance measurement date are only entitled to one-tenth ( 10% ) of the regular quarterly distributions payable on common partnership units. Under ASC 718, the 2016 MYLTIP awards have an aggregate value of approximately $17.3 million , which amount will generally be amortized into earnings over the four -year plan period under the graded vesting method. On February 1, 2016, the Company completed the sale of its 415 Main Street property located in Cambridge, Massachusetts to the tenant for a gross sale price of approximately $105.4 million , which exceeds its carrying value. As part of its lease signed on July 14, 2004, the tenant was granted a fixed price option to purchase the building at the beginning of the 11 th lease year, which option was exercised by the tenant on October 22, 2014. 415 Main Street is an office/technical property with approximately 231,000 net rentable square feet. On February 3, 2016, the Company entered into a lease termination agreement with a tenant for an approximately 85,000 square foot lease at its 250 West 55th Street property located in New York City. The lease was scheduled to expire on February 28, 2035. In consideration for the termination of the lease, the tenant paid the Company approximately $45.0 million , which will be recognized during the three months ending March 31, 2016. On February 4, 2016, the measurement period for the Company’s 2013 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 109.5% of target or an aggregate of approximately $13.5 million . On February 8, 2016, Boston Properties, Inc. issued 18,521 shares of restricted common stock and Boston Properties Limited Partnership issued 139,435 LTIP units under the 2012 Plan to certain employees of Boston Properties, Inc.

Real Estate and Accumulated Dep

Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2015
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation Disclosure [Text Block]	Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Property Name Type Location Encumbrances Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Land Building 767 Fifth Avenue (the General Motors Building) Office New York, NY $ 1,377,986 $ 1,796,252 $ 1,532,654 $ 45,800 $ 1,796,252 $ 1,578,454 $ — $ — $ 3,374,706 $ 128,488 1968 (1) Embarcadero Center Office San Francisco, CA 348,886 179,697 847,410 332,276 195,987 1,163,396 — — 1,359,383 542,103 1970/1989 (1) Prudential Center Office Boston, MA — 92,077 734,594 526,740 107,426 1,082,583 1,714 161,688 1,353,411 446,792 1965/1993/2002 (1) 399 Park Avenue Office New York, NY — 339,200 700,358 110,972 354,107 796,423 — — 1,150,530 265,266 1961 (1) 200 Clarendon Street and Garage (formerly the John Hancock Tower and Garage) Office Boston, MA — 219,543 667,884 112,229 219,616 776,755 3,285 — 999,656 128,815 1976 (1) 601 Lexington Avenue Office New York, NY 699,061 241,600 494,782 231,812 289,639 677,238 1,317 — 968,194 250,128 1977/1997 (1) 250 West 55th Street Office New York, NY — 285,263 603,167 16,488 285,263 619,655 — — 904,918 28,349 2014 (1) Times Square Tower Office New York, NY — 165,413 380,438 84,722 169,193 461,380 — — 630,573 164,767 2004 (1) Carnegie Center Office Princeton, NJ — 105,107 377,259 128,069 103,064 464,086 2,475 40,810 610,435 198,387 1983-1999 (1) 100 Federal Street Office Boston, MA — 131,067 435,954 15,555 131,067 450,933 576 — 582,576 60,125 1971-1975 (1) Atlantic Wharf Office Boston, MA — 63,988 454,537 16,376 63,988 470,913 — — 534,901 70,552 2011 (1) 510 Madison Avenue Office New York, NY — 103,000 253,665 19,575 103,000 273,240 — — 376,240 34,640 2012 (1) Fountain Square Office Reston, VA 213,499 56,853 306,298 12,459 56,853 318,757 — — 375,610 39,508 1986-1990 (1) 599 Lexington Avenue Office New York, NY 750,000 81,040 100,507 149,551 87,852 243,246 — — 331,098 160,354 1986 (1) 680 Folsom Street Office San Francisco, CA — 72,545 219,766 7,348 72,545 227,114 — — 299,659 13,091 2014 (1) South of Market and Democracy Tower Office Reston, VA — 13,603 237,479 11,977 13,687 249,372 — — 263,059 70,437 2008-2009 (1) Bay Colony Corporate Center Office Waltham, MA — 18,789 148,451 65,997 18,789 214,448 — — 233,237 40,812 1985-1989 (1) Gateway Center Office San Francisco, CA — 28,255 139,245 54,027 30,627 190,900 — — 221,527 94,083 1984/1986/2002 (1) 535 Mission Street Office San Francisco, CA — 40,933 148,378 — 40,933 148,378 — — 189,311 3,221 2015 (1) 2200 Pennsylvania Avenue Office Washington, DC — — 183,541 5,230 — 188,771 — — 188,771 33,039 2011 (1) Mountain View Research Park Office Mountain View, CA — 95,066 68,373 5,581 95,066 73,954 — — 169,020 9,581 1977-1981/2007-2013 (1) Reservoir Place Office Waltham, MA — 18,605 92,619 46,547 20,118 128,975 — 8,678 157,771 57,706 1955/1987 (1) 1333 New Hampshire Avenue Office Washington, DC — 34,032 85,660 10,841 35,382 95,151 — — 130,533 35,457 1996 (1) Kingstowne Towne Center Office Alexandria, VA — 18,021 109,038 1,276 18,062 110,273 — — 128,335 33,374 2003-2006 (1) 1330 Connecticut Avenue Office Washington, DC — 25,982 82,311 19,098 27,135 100,256 — — 127,391 45,063 1984 (1) Capital Gallery Office Washington, DC — 4,725 29,565 88,569 8,662 114,197 — — 122,859 57,489 1981/2006 (1) Weston Corporate Center Office Weston, MA — 25,753 92,312 (123 ) 25,854 92,088 — — 117,942 17,023 2010 (1) One Freedom Square Office Reston, VA — 9,929 84,504 19,613 11,293 102,753 — — 114,046 41,106 2000 (1) Two Freedom Square Office Reston, VA — 13,930 77,739 21,374 15,420 97,623 — — 113,043 41,164 2001 (1) Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Property Name Type Location Encumbrances Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Land Building One and Two Reston Overlook Office Reston, VA — 16,456 66,192 22,385 16,179 88,854 — — 105,033 37,165 1999 (1) Discovery Square Office Reston, VA — 11,198 71,782 21,234 12,533 91,681 — — 104,214 35,835 2001 (1) 415 Main Street Office Cambridge, MA — 3,457 97,136 2,986 4,125 99,454 — — 103,579 59,405 2006 (1) 355 Main Street Office Cambridge, MA — 18,863 53,346 28,822 21,173 79,858 — — 101,031 23,372 1981/1996/2013 (1) 140 Kendrick Street Office Needham, MA — 18,095 66,905 15,075 19,092 80,983 — — 100,075 23,191 2000 (1) 90 Broadway Office Cambridge, MA — 19,104 52,078 17,386 20,785 67,783 — — 88,568 14,394 1983/1998/2013 (1) 230 CityPoint Office Waltham, MA — 13,189 49,823 18,800 13,593 68,219 — — 81,812 20,265 1992 (1) Waltham Weston Corporate Center Office Waltham, MA — 10,385 60,694 8,907 11,097 68,889 — — 79,986 24,699 2003 (1) 77 CityPoint Office Waltham, MA — 13,847 60,383 5,605 13,873 65,962 — — 79,835 18,930 2008 (1) North First Business Park Office San Jose, CA — 58,402 13,069 4,028 23,377 16,214 35,908 — 75,499 14,139 1981 (1) 300 Binney Street Office Cambridge, MA — 18,080 51,262 140 18,080 51,402 — — 69,482 4,375 2013 (1) 2440 West El Camino Real Office Mountain View, CA — 16,741 51,285 1,422 16,741 52,707 — — 69,448 8,185 1987/2003 (1) Reston Corporate Center Office Reston, VA — 9,135 50,857 6,464 10,148 56,308 — — 66,456 23,962 1984 (1) Wisconsin Place Office Chevy Chase, MD — — 53,349 12,787 — 66,136 — — 66,136 18,272 2009 (1) New Dominion Technology Park, Bldg. Two Office Herndon, VA — 5,584 51,868 3,911 6,510 54,853 — — 61,363 20,110 2004 (1) Sumner Square Office Washington, DC — 624 28,745 26,196 1,478 54,087 — — 55,565 26,923 1985 (1) 200 West Street Office Waltham, MA — 16,148 24,983 10,102 16,813 34,420 — — 51,233 18,034 1999 (1) New Dominion Technology Park, Bldg. One Office Herndon, VA 38,494 3,880 43,227 3,883 4,583 46,407 — — 50,990 22,760 2001 (1) 191 Spring Street Office Lexington, MA — 2,850 27,166 18,610 3,151 45,475 — — 48,626 32,535 1971/1995 (1) University Place Office Cambridge, MA 10,788 — 37,091 9,483 390 46,184 — — 46,574 23,635 1985 (1) 2600 Tower Oaks Boulevard Office Rockville, MD — 4,243 31,125 8,656 4,785 39,239 — — 44,024 18,386 2001 (1) 255 Main Street Office Cambridge, MA — 134 25,110 18,559 548 43,255 — — 43,803 27,153 1987 (1) Quorum Office Park Office Chelmsford, MA — 3,750 32,454 5,814 5,187 36,831 — — 42,018 14,671 2001 (1) 500 E Street Office Washington, DC — 109 22,420 13,144 2,379 33,294 — — 35,673 22,616 1987 (1) 150 Broadway Office Cambridge, MA — 850 25,042 8,623 1,323 33,192 — — 34,515 14,073 1999 (1) 325 Main Street Office Cambridge, MA — 174 12,200 12,368 965 23,777 — — 24,742 11,339 1987/2013 (1) 105 Broadway Office Cambridge, MA — 1,299 12,943 7,177 2,395 19,024 — — 21,419 12,556 1990 (1) 40 Shattuck Road Office Andover, MA — 709 14,740 3,184 893 17,740 — — 18,633 6,846 2001 (1) Lexington Office Park Office Lexington, MA — 998 1,426 16,099 1,264 17,259 — — 18,523 11,730 1982 (1) 201 Spring Street Office Lexington, MA — 2,849 15,303 (154 ) 3,124 14,874 — — 17,998 6,987 1997 (1) The Point (formerly 99 Third Avenue Retail) Office Waltham, MA — 6,395 10,040 — 6,395 10,040 — — 16,435 76 2015 (1) 91 Hartwell Avenue Office Lexington, MA — 784 6,464 8,192 941 14,499 — — 15,440 8,525 1985 (1) 92-100 Hayden Avenue Office Lexington, MA — 594 6,748 8,034 802 14,574 — — 15,376 11,412 1985 (1) 690 Folsom Street Office San Francisco, CA — 3,219 11,038 — 3,219 11,038 — — 14,257 334 2015 (1) 195 West Street Office Waltham, MA — 1,611 6,652 4,340 1,858 10,745 — — 12,603 7,071 1990 (1) 181 Spring Street Office Lexington, MA — 1,066 9,520 1,993 1,160 11,419 — — 12,579 4,580 1999 (1) Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Property Name Type Location Encumbrances Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Land Building 33 Hayden Avenue Office Lexington, MA — 266 3,234 8,787 425 11,862 — — 12,287 6,586 1979 (1) 145 Broadway Office Cambridge, MA — 121 5,535 5,305 324 10,637 — — 10,961 7,864 1984 (1) 7501 Boston Boulevard, Building Seven Office Springfield, VA — 665 9,273 520 791 9,667 — — 10,458 4,355 1997 (1) 7435 Boston Boulevard, Building One Office Springfield, VA — 392 3,822 4,218 659 7,773 — — 8,432 6,052 1982 (1) 250 Binney Street Office Cambridge, MA — 110 4,483 3,593 273 7,913 — — 8,186 4,303 1983 (1) 7450 Boston Boulevard, Building Three Office Springfield, VA — 1,165 4,681 1,880 1,430 6,296 — — 7,726 3,226 1987 (1) 8000 Grainger Court, Building Five Office Springfield, VA — 366 4,282 2,684 601 6,731 — — 7,332 5,336 1984 (1) 453 Ravendale Drive Office Mountain View, CA — 5,477 1,090 235 5,479 1,323 — — 6,802 265 1977 (1) 7500 Boston Boulevard, Building Six Office Springfield, VA — 138 3,749 2,617 406 6,098 — — 6,504 4,499 1985 (1) 7300 Boston Boulevard, Building Thirteen Office Springfield, VA — 608 4,773 709 661 5,429 — — 6,090 4,626 2002 (1) 7601 Boston Boulevard, Building Eight Office Springfield, VA — 200 878 4,924 551 5,451 — — 6,002 3,849 1986 (1) 8000 Corporate Court, Building Eleven Office Springfield, VA — 136 3,071 1,615 775 4,047 — — 4,822 2,639 1989 (1) 7375 Boston Boulevard, Building Ten Office Springfield, VA — 23 2,685 1,003 93 3,618 — — 3,711 2,464 1988 (1) 7374 Boston Boulevard, Building Four Office Springfield, VA — 241 1,605 1,735 398 3,183 — — 3,581 2,345 1984 (1) 7451 Boston Boulevard, Building Two Office Springfield, VA — 249 1,542 1,661 613 2,839 — — 3,452 2,233 1982 (1) 32 Hartwell Avenue Office Lexington, MA — 168 1,943 1,193 314 2,990 — — 3,304 1,786 1968-1979/1987 (1) 164 Lexington Road Office Billerica, MA — 592 1,370 319 643 1,638 — — 2,281 786 1982 (1) 17 Hartwell Avenue Office Lexington, MA — 26 150 614 65 725 — — 790 323 1968 (1) The Avant at Reston Town Center Residential Reston, VA — 20,350 91,995 813 20,350 92,808 — — 113,158 4,833 2014 (1) The Lofts at Atlantic Wharf Residential Boston, MA — 3,529 54,891 1,579 3,529 56,470 — — 59,999 6,596 2011 (1) Boston Marriott Cambridge Hotel Cambridge, MA — 478 37,918 35,665 1,201 72,860 — — 74,061 48,162 1986 (1) Kendall Center Green Garage (formerly Cambridge Center East Garage) Garage Cambridge, MA — — 35,035 4,254 103 39,186 — — 39,289 8,610 1984 (1) Kendall Center Yellow Garage (formerly Cambridge Center West Garage) Garage Cambridge, MA — 1,256 15,697 1,571 1,434 17,090 — — 18,524 4,269 2006 (1) Kendall Center Blue Garage (formerly Cambridge Center North Garage) Garage Cambridge, MA — 1,163 11,633 2,770 1,579 13,987 — — 15,566 8,941 1990 (1) Salesforce Tower Development San Francisco, CA — — — 429,767 — — — 429,767 429,767 — N/A N/A 601 Massachusetts Avenue Development Washington, DC — — — 253,176 95,322 140,791 — 17,063 253,176 1,531 N/A N/A 10 CityPoint Development Waltham, MA — — — 70,389 163 — — 70,226 70,389 — N/A N/A Reston Signature Site Development Reston, VA — — — 38,886 — — 12,678 26,208 38,886 — N/A N/A Cambridge Residential / 88 Ames Development Cambridge, MA — — — 9,495 — — — 9,495 9,495 — N/A N/A Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Property Name Type Location Encumbrances Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Land Building Springfield Metro Center Land Springfield, VA — — — 34,870 — — 34,870 — 34,870 — N/A N/A Tower Oaks Master Plan Land Rockville, MD — — — 29,022 — — 29,022 — 29,022 — N/A N/A Plaza at Almaden Land San Jose, CA — — — 29,010 — — 29,010 — 29,010 — N/A N/A 6601 & 6605 Springfield Center Drive Land Springfield, VA — — — 13,866 — — 13,866 — 13,866 — N/A N/A 214 Third Avenue Land Waltham, MA — — — 13,415 — 132 13,283 — 13,415 — N/A N/A 103 Fourth Avenue Land Waltham, MA — — — 11,927 — — 11,927 — 11,927 — N/A N/A Reston Gateway Land Reston, VA — — — 10,294 — — 10,294 — 10,294 — N/A N/A 20 CityPoint Land Waltham, MA — — — 10,258 — — 10,258 — 10,258 — N/A N/A Reston Eastgate Land Reston, VA — — — 9,215 — — 9,215 — 9,215 — N/A N/A Washingtonian North Land Gaithersburg, MD — — — 8,836 — — 8,836 — 8,836 — N/A N/A Crane Meadow Land Marlborough, MA — — — 8,727 — — 8,727 — 8,727 — N/A N/A Broad Run Business Park Land Loudoun County, VA — — — 6,399 — — 6,399 — 6,399 — N/A N/A North First Master Plan Land San Jose, CA — — — 2,999 — — 2,999 — 2,999 — N/A N/A Fourth and Harrison (formerly 425 Fourth Street) Land San Francisco, CA — — — 2,920 — — 2,920 — 2,920 — N/A N/A Kendall Center Master Plan (formerly Cambridge Master Plan) Land Cambridge, MA — — — 1,403 — — 1,403 — 1,403 — N/A N/A 30 Shattuck Road Land Andover, MA — — — 1,213 — — 1,213 — 1,213 — N/A N/A $ 3,438,714 (2 ) $ 4,602,809 $ 11,248,289 $ 3,600,585 $ 4,806,021 $ 13,629,532 $ 252,195 $ 763,935 $ 19,451,683 $ 3,905,940 Note: Total Real Estate does not include Furniture, Fixtures and Equipment totaling approximately $29,852 . Accumulated Depreciation does not include approximately $19,954 of accumulated depreciation related to Furniture, Fixtures and Equipment. The aggregate cost and accumulated depreciation for tax purposes was approximately $15.0 billion and $3.0 billion , respectively. (1) Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years. (2) Includes the unamortized balance of the historical fair value adjustment totaling approximately $80.2 million Boston Properties, Inc. Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) A summary of activity for real estate and accumulated depreciation is as follows: 2015 2014 2013 Real Estate: Balance at the beginning of the year $ 19,208,417 $ 18,953,601 $ 14,869,887 Additions to/improvements of real estate 700,792 594,296 4,410,622 Assets sold/written-off (457,526 ) (339,480 ) (326,908 ) Balance at the end of the year $ 19,451,683 $ 19,208,417 $ 18,953,601 Accumulated Depreciation: Balance at the beginning of the year $ 3,529,978 $ 3,145,701 $ 2,919,479 Depreciation expense 486,450 456,176 419,908 Assets sold/written-off (110,488 ) (71,899 ) (193,686 ) Balance at the end of the year $ 3,905,940 $ 3,529,978 $ 3,145,701 Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.
Boston Properties Limited Partnership [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation Disclosure [Text Block]	Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Property Name Type Location Encumbrances Land Building 767 Fifth Avenue (the General Motors Building) Office New York, NY $ 1,377,986 $ 1,796,252 $ 1,532,654 $ 45,800 $ 1,796,252 $ 1,578,454 $ — $ — $ 3,374,706 $ 128,488 1968 (1) Prudential Center Office Boston, MA — 92,077 734,594 466,370 92,328 1,037,311 1,714 161,688 1,293,041 435,437 1965/1993/2002 (1) Embarcadero Center Office San Francisco, CA 348,886 179,697 847,410 269,895 180,420 1,116,582 — — 1,297,002 530,307 1970/1989 (1) 399 Park Avenue Office New York, NY — 339,200 700,358 51,364 339,200 751,722 — — 1,090,922 254,028 1961 (1) 200 Clarendon Street and Garage (formerly the John Hancock Tower and Garage) Office Boston, MA — 219,543 667,884 112,229 219,616 776,755 3,285 — 999,656 128,815 1976 (1) 601 Lexington Avenue Office New York, NY 699,061 241,600 494,782 190,393 279,281 646,177 1,317 — 926,775 242,358 1977/1997 (1) 250 West 55th Street Office New York, NY — 285,263 603,167 16,488 285,263 619,655 — — 904,918 28,349 2014 (1) Carnegie Center Office Princeton, NJ — 105,107 377,259 110,751 98,733 451,099 2,475 40,810 593,117 195,128 1983-1999 (1) Times Square Tower Office New York, NY — 165,413 380,438 46,743 159,694 432,900 — — 592,594 157,622 2004 (1) 100 Federal Street Office Boston, MA — 131,067 435,954 15,555 131,067 450,933 576 — 582,576 60,125 1971-1975 (1) Atlantic Wharf Office Boston, MA — 63,988 454,537 16,376 63,988 470,913 — — 534,901 70,552 2011 (1) 510 Madison Avenue Office New York, NY — 103,000 253,665 19,575 103,000 273,240 — — 376,240 34,640 2012 (1) Fountain Square Office Reston, VA 213,499 56,853 306,298 12,459 56,853 318,757 — — 375,610 39,508 1986-1990 (1) 599 Lexington Avenue Office New York, NY 750,000 81,040 100,507 122,309 81,040 222,816 — — 303,856 155,235 1986 (1) 680 Folsom Street Office San Francisco, CA — 72,545 219,766 7,348 72,545 227,114 — — 299,659 13,091 2014 (1) South of Market and Democracy Tower Office Reston, VA — 13,603 237,479 11,641 13,603 249,120 — — 262,723 70,389 2008-2009 (1) Bay Colony Corporate Center Office Waltham, MA — 18,789 148,451 65,997 18,789 214,448 — — 233,237 40,812 1985-1989 (1) Gateway Center Office San Francisco, CA — 28,255 139,245 47,638 29,029 186,109 — — 215,138 92,882 1984/1986/2002 (1) 535 Mission Street Office San Francisco, CA — 40,933 148,378 — 40,933 148,378 — — 189,311 3,221 2015 (1) 2200 Pennsylvania Avenue Office Washington, DC — — 183,541 5,230 — 188,771 — — 188,771 33,039 2011 (1) Mountain View Research Park Office Mountain View, CA — 95,066 68,373 5,581 95,066 73,954 — — 169,020 9,581 1977-1981/2007-2013 (1) Reservoir Place Office Waltham, MA — 18,605 92,619 42,472 19,099 125,919 — 8,678 153,696 56,939 1955/1987 (1) Kingstowne Towne Center Office Alexandria, VA — 18,021 109,038 1,112 18,021 110,150 — — 128,171 33,350 2003-2006 (1) 1333 New Hampshire Avenue Office Washington, DC — 34,032 85,660 5,447 34,032 91,107 — — 125,139 34,441 1996 (1) 1330 Connecticut Avenue Office Washington, DC — 25,982 82,311 14,485 25,982 96,796 — — 122,778 44,193 1984 (1) Weston Corporate Center Office Weston, MA — 25,753 92,312 (123 ) 25,854 92,088 — — 117,942 17,023 2010 (1) Capital Gallery Office Washington, DC — 4,725 29,565 78,438 6,128 106,600 — — 112,728 55,581 1981/2006 (1) One Freedom Square Office Reston, VA — 9,929 84,504 13,976 9,883 98,526 — — 108,409 40,044 2000 (1) Two Freedom Square Office Reston, VA — 13,930 77,739 15,162 13,866 92,965 — — 106,831 39,996 2001 (1) 415 Main Street Office Cambridge, MA — 3,457 97,136 316 3,457 97,452 — — 100,909 58,907 2006 (1) 355 Main Street Office Cambridge, MA — 18,863 53,346 28,524 21,098 79,635 — — 100,733 23,319 1981/1996/2013 (1) One and Two Reston Overlook Office Reston, VA — 16,456 66,192 17,967 15,074 85,541 — — 100,615 36,334 1999 (1) Discovery Square Office Reston, VA — 11,198 71,782 15,689 11,146 87,523 — — 98,669 34,789 2001 (1) 140 Kendrick Street Office Needham, MA — 18,095 66,905 11,085 18,095 77,990 — — 96,085 22,441 2000 (1) Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Property Name Type Location Encumbrances Land Building 90 Broadway Office Cambridge, MA — 19,104 52,078 17,207 20,741 67,648 — — 88,389 14,366 1983/1998/2013 (1) 230 CityPoint Office Waltham, MA — 13,189 49,823 17,183 13,189 67,006 — — 80,195 19,965 1992 (1) 77 CityPoint Office Waltham, MA — 13,847 60,383 5,500 13,847 65,883 — — 79,730 18,914 2008 (1) Waltham Weston Corporate Center Office Waltham, MA — 10,385 60,694 5,920 10,350 66,649 — — 76,999 24,136 2003 (1) North First Business Park Office San Jose, CA — 58,402 13,069 4,005 23,371 16,197 35,908 — 75,476 14,139 1981 (1) 300 Binney Street Office Cambridge, MA — 18,080 51,262 140 18,080 51,402 — — 69,482 4,375 2013 (1) 2440 West El Camino Real Office Mountain View, CA — 16,741 51,285 1,422 16,741 52,707 — — 69,448 8,185 1987/2003 (1) Wisconsin Place Office Chevy Chase, MD — — 53,349 12,787 — 66,136 — — 66,136 18,272 2009 (1) Reston Corporate Center Office Reston, VA — 9,135 50,857 3,853 9,496 54,349 — — 63,845 23,471 1984 (1) New Dominion Technology Park, Bldg. Two Office Herndon, VA — 5,584 51,868 166 5,574 52,044 — — 57,618 19,401 2004 (1) Sumner Square Office Washington, DC — 624 28,745 24,116 958 52,527 — — 53,485 26,534 1985 (1) 200 West Street Office Waltham, MA — 16,148 24,983 7,441 16,148 32,424 — — 48,572 17,532 1999 (1) New Dominion Technology Park, Bldg. One Office Herndon, VA 38,494 3,880 43,227 1,074 3,880 44,301 — — 48,181 22,230 2001 (1) 191 Spring Street Office Lexington, MA — 2,850 27,166 17,411 2,850 44,577 — — 47,427 32,307 1971/1995 (1) University Place Office Cambridge, MA 10,788 — 37,091 8,033 27 45,097 — — 45,124 23,365 1985 (1) 255 Main Street Office Cambridge, MA — 134 25,110 16,903 134 42,013 — — 42,147 26,843 1987 (1) 2600 Tower Oaks Boulevard Office Rockville, MD — 4,243 31,125 6,493 4,244 37,617 — — 41,861 17,977 2001 (1) Quorum Office Park Office Chelmsford, MA — 3,750 32,454 4,115 4,762 35,557 — — 40,319 14,352 2001 (1) 150 Broadway Office Cambridge, MA — 850 25,042 6,618 822 31,688 — — 32,510 13,693 1999 (1) 500 E Street Office Washington, DC — 109 22,420 9,904 1,569 30,864 — — 32,433 22,008 1987 (1) 325 Main Street Office Cambridge, MA — 174 12,200 11,597 772 23,199 — — 23,971 11,192 1987/2013 (1) 105 Broadway Office Cambridge, MA — 1,299 12,943 5,071 1,868 17,445 — — 19,313 12,158 1990 (1) 40 Shattuck Road Office Andover, MA — 709 14,740 2,448 709 17,188 — — 17,897 6,707 2001 (1) Lexington Office Park Office Lexington, MA — 998 1,426 15,335 1,073 16,686 — — 17,759 11,589 1982 (1) 201 Spring Street Office Lexington, MA — 2,849 15,303 (1,253 ) 2,849 14,050 — — 16,899 6,779 1997 (1) The Point (formerly 99 Third Avenue Retail) Office Waltham, MA — 6,395 10,040 — 6,395 10,040 — — 16,435 76 2015 (1) 91 Hartwell Avenue Office Lexington, MA — 784 6,464 7,565 784 14,029 — — 14,813 8,405 1985 (1) 92-100 Hayden Avenue Office Lexington, MA — 594 6,748 7,305 619 14,028 — — 14,647 11,274 1985 (1) 690 Folsom Street Office San Francisco, CA — 3,219 11,038 — 3,219 11,038 — — 14,257 334 2015 (1) 181 Spring Street Office Lexington, MA — 1,066 9,520 1,616 1,066 11,136 — — 12,202 4,509 1999 (1) 33 Hayden Avenue Office Lexington, MA — 266 3,234 8,150 266 11,384 — — 11,650 6,466 1979 (1) 195 West Street Office Waltham, MA — 1,611 6,652 3,351 1,611 10,003 — — 11,614 6,882 1990 (1) 145 Broadway Office Cambridge, MA — 121 5,535 4,492 121 10,027 — — 10,148 7,713 1984 (1) 7501 Boston Boulevard, Building Seven Office Springfield, VA — 665 9,273 15 665 9,288 — — 9,953 4,259 1997 (1) 7435 Boston Boulevard, Building One Office Springfield, VA — 392 3,822 3,525 486 7,253 — — 7,739 5,922 1982 (1) Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Property Name Type Location Encumbrances Land Building 250 Binney Street Office Cambridge, MA — 110 4,483 2,939 110 7,422 — — 7,532 4,183 1983 (1) 7450 Boston Boulevard, Building Three Office Springfield, VA — 1,165 4,681 1,466 1,327 5,985 — — 7,312 3,145 1987 (1) 453 Ravendale Drive Office Mountain View, CA — 5,477 1,090 233 5,477 1,323 — — 6,800 265 1977 (1) 8000 Grainger Court, Building Five Office Springfield, VA — 366 4,282 2,090 453 6,285 — — 6,738 5,225 1984 (1) 7500 Boston Boulevard, Building Six Office Springfield, VA — 138 3,749 2,084 273 5,698 — — 5,971 4,399 1985 (1) 7300 Boston Boulevard, Building Thirteen Office Springfield, VA — 608 4,773 497 608 5,270 — — 5,878 4,586 2002 (1) 7601 Boston Boulevard, Building Eight Office Springfield, VA — 200 878 4,231 378 4,931 — — 5,309 3,719 1986 (1) 8000 Corporate Court, Building Eleven Office Springfield, VA — 136 3,071 1,264 687 3,784 — — 4,471 2,570 1989 (1) 7375 Boston Boulevard, Building Ten Office Springfield, VA — 23 2,685 822 47 3,483 — — 3,530 2,432 1988 (1) 7374 Boston Boulevard, Building Four Office Springfield, VA — 241 1,605 1,352 303 2,895 — — 3,198 2,275 1984 (1) 7451 Boston Boulevard, Building Two Office Springfield, VA — 249 1,542 1,348 535 2,604 — — 3,139 2,173 1982 (1) 32 Hartwell Avenue Office Lexington, MA — 168 1,943 607 168 2,550 — — 2,718 1,674 1968-1979/1987 (1) 164 Lexington Road Office Billerica, MA — 592 1,370 117 592 1,487 — — 2,079 745 1982 (1) 17 Hartwell Avenue Office Lexington, MA — 26 150 457 26 607 — — 633 293 1968 (1) The Avant at Reston Town Center Residential Reston, VA — 20,350 91,995 813 20,350 92,808 — — 113,158 4,833 2014 (1) The Lofts at Atlantic Wharf Residential Boston, MA — 3,529 54,891 1,579 3,529 56,470 — — 59,999 6,596 2011 (1) Boston Marriott Cambridge Hotel Cambridge, MA — 478 37,918 32,774 478 70,692 — — 71,170 47,620 1986 (1) Kendall Center Green Garage (formerly Cambridge Center East Garage) Garage Cambridge, MA — — 35,035 3,840 — 38,875 — — 38,875 8,534 1984 (1) Kendall Center Yellow Garage (formerly Cambridge Center West Garage) Garage Cambridge, MA — 1,256 15,697 859 1,256 16,556 — — 17,812 4,140 2006 (1) Kendall Center Blue Garage (formerly Cambridge Center North Garage) Garage Cambridge, MA — 1,163 11,633 1,105 1,163 12,738 — — 13,901 8,630 1990 (1) Salesforce Tower Development San Francisco, CA — — — 429,767 — — — 429,767 429,767 — N/A N/A 601 Massachusetts Avenue Development Washington, DC — — — 253,166 95,312 140,791 — 17,063 253,166 1,531 N/A N/A 10 CityPoint Development Waltham, MA — — — 70,226 — — — 70,226 70,226 — N/A N/A Reston Signature Site Development Reston, VA — — — 38,886 — — 12,678 26,208 38,886 — N/A N/A Cambridge Residential / 88 Ames Development Cambridge, MA — — — 9,495 — — — 9,495 9,495 — N/A N/A Springfield Metro Center Land Springfield, VA — — — 34,870 — — 34,870 — 34,870 — N/A N/A Tower Oaks Master Plan Land Rockville, MD — — — 29,022 — — 29,022 — 29,022 — N/A N/A Plaza at Almaden Land San Jose, CA — — — 29,010 — — 29,010 — 29,010 — N/A N/A Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Property Name Type Location Encumbrances Land Building 6601 & 6605 Springfield Center Drive Land Springfield, VA — — — 13,866 — — 13,866 — 13,866 — N/A N/A 214 Third Avenue Land Waltham, MA — — — 13,415 — 132 13,283 — 13,415 — N/A N/A 103 Fourth Avenue Land Waltham, MA — — — 11,927 — — 11,927 — 11,927 — N/A N/A Reston Gateway Land Reston, VA — — — 10,294 — — 10,294 — 10,294 — N/A N/A 20 CityPoint Land Waltham, MA — — — 10,258 — — 10,258 — 10,258 — N/A N/A Reston Eastgate Land Reston, VA — — — 9,215 — — 9,215 — 9,215 — N/A N/A Washingtonian North Land Gaithersburg, MD — — — 8,836 — — 8,836 — 8,836 — N/A N/A Crane Meadow Land Marlborough, MA — — — 8,727 — — 8,727 — 8,727 — N/A N/A Broad Run Business Park Land Loudoun County, VA — — — 6,399 — — 6,399 — 6,399 — N/A N/A North First Master Plan Land San Jose, CA — — — 2,999 — — 2,999 — 2,999 — N/A N/A Fourth and Harrison (formerly 425 Fourth Street) Land San Francisco, CA — — — 2,920 — — 2,920 — 2,920 — N/A N/A Kendall Center Master Plan (formerly Cambridge Master Plan) Land Cambridge, MA — — — 1,403 — — 1,403 — 1,403 — N/A N/A 30 Shattuck Road Land Andover, MA — — — 1,213 — — 1,213 — 1,213 — N/A N/A $ 3,438,714 (2 ) $ 4,602,809 $ 11,248,289 $ 3,180,191 $ 4,700,793 $ 13,314,366 $ 252,195 $ 763,935 $ 19,031,289 $ 3,826,862 Note: Total Real Estate does not include Furniture, Fixtures and Equipment totaling approximately $29,852 . Accumulated Depreciation does not include approximately $19,954 of accumulated depreciation related to Furniture, Fixtures and Equipment. The aggregate cost and accumulated depreciation for tax purposes was approximately $16.8 billion and $3.4 billion , respectively. (1) Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years. (2) Includes the unamortized balance of the historical fair value adjustment totaling approximately $80.2 million . Boston Properties Limited Partnership Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) A summary of activity for real estate and accumulated depreciation is as follows: 2015 2014 2013 Real Estate: Balance at the beginning of the year $ 18,786,572 $ 18,523,277 $ 14,431,521 Additions to/improvements of real estate 700,792 594,296 4,410,622 Assets sold/written-off (456,075 ) (331,001 ) (318,866 ) Balance at the end of the year $ 19,031,289 $ 18,786,572 $ 18,523,277 Accumulated Depreciation: Balance at the beginning of the year $ 3,458,640 $ 3,081,040 $ 2,862,302 Depreciation expense 478,457 447,667 411,860 Assets sold/written-off (110,235 ) (70,067 ) (193,122 ) Balance at the end of the year $ 3,826,862 $ 3,458,640 $ 3,081,040 Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

Summary Of Significant Accoun30

Summary Of Significant Accounting Policies Summary Of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Real Estate	Real Estate Upon acquisitions of real estate that constitutes a business, which includes the consolidation of previously unconsolidated joint ventures, the Company assesses the fair value of acquired tangible and intangible assets (including land, buildings, tenant improvements, “above-” and “below-market” leases, leasing and assumed financing origination costs, acquired in-place leases, other identified intangible assets and assumed liabilities) and allocates the purchase price to the acquired assets and assumed liabilities, including land and buildings as if vacant. The Company assesses and considers fair value based on estimated cash flow projections that utilize discount and/or capitalization rates that it deems appropriate, as well as available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known and anticipated trends, and market and economic conditions. The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant. The Company also considers an allocation of purchase price of other acquired intangibles, including acquired in-place leases that may have a customer relationship intangible value, including (but not limited to) the nature and extent of the existing relationship with the tenants, the tenants’ credit quality and expectations of lease renewals. Based on its acquisitions to date, the Company’s allocation to customer relationship intangible assets has been immaterial. The Company records acquired “above-” and “below-market” leases at their fair values (using a discount rate which reflects the risks associated with the leases acquired) equal to the difference between (1) the contractual amounts to be paid pursuant to each in-place lease and (2) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the initial term plus the term of any below-market fixed rate renewal options for below- market leases. Acquired “above-” and “below-market” lease values have been reflected within Prepaid Expenses and Other Assets and Other Liabilities, respectively, in the Company’s Consolidated Balance Sheets. Other intangible assets acquired include amounts for in-place lease values that are based on the Company’s evaluation of the specific characteristics of each tenant’s lease. Factors to be considered include estimates of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, the Company considers leasing commissions, legal and other related expenses. Management reviews its long-lived assets for impairment following the end of each quarter and when there is an event or change in circumstances that indicates an impairment in value. An impairment loss is recognized if the carrying amount of its assets is not recoverable and exceeds its fair value. If such criteria are present, an impairment loss is recognized based on the excess of the carrying amount of the asset over its fair value. The evaluation of anticipated cash flows is highly subjective and is based in part on assumptions regarding future occupancy, rental rates and capital requirements that could differ materially from actual results in future periods. Since cash flows on properties considered to be “long-lived assets to be held and used” are considered on an undiscounted basis to determine whether an asset has been impaired, the Company’s established strategy of holding properties over the long term directly decreases the likelihood of recording an impairment loss. If the Company’s strategy changes or market conditions otherwise dictate an earlier sale date, an impairment loss may be recognized and such loss could be material. If the Company determines that an impairment has occurred, the affected assets must be reduced to their fair value, less cost to sell. Guidance in Accounting Standards Codification (“ASC”) 360 “Property Plant and Equipment” (“ASC 360”) requires that qualifying assets and liabilities and the results of operations that have been sold, or otherwise qualify as “held for sale,” be presented as discontinued operations in all periods presented if the property operations are expected to be eliminated and the Company will not have significant continuing involvement following the sale. The components of the property’s net income that are reflected as discontinued operations include the net gain (or loss) upon the disposition of the property held for sale, operating results, depreciation and interest expense (if the property is subject to a secured loan). The Company generally considers assets to be “held for sale” when the transaction has been approved by Boston Properties, Inc.’s Board of Directors, or a committee thereof, and there are no known significant contingencies relating to the sale, such that a sale of the property within one year is considered probable. Following the classification of a property as “held for sale,” no further depreciation is recorded on the assets, and the asset is written down to the lower of carrying value or fair market value, less cost to sell. On April 10, 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity” (“ASU 2014-08”). ASU 2014-08 clarifies that discontinued operations presentation applies only to disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results (e.g., a disposal of a major geographical area, a major line of business, a major equity method investment or other major parts of an entity). ASU 2014-08 is effective prospectively for reporting periods beginning after December 15, 2014. Early adoption is permitted, and the Company early adopted ASU 2014-08 during the first quarter of 2014. The Company’s adoption of ASU 2014-08 resulted in the operating results and gains on sales of real estate from operating properties sold during the years ended December 31, 2015 and 2014 not being reflected within Discontinued Operations in the Company’s Consolidated Statements of Operations (See Note 3 ). Real estate is stated at depreciated cost. A variety of costs are incurred in the acquisition, development and leasing of properties. The cost of buildings and improvements includes the purchase price of property, legal fees and other acquisition costs. The Company expenses costs that it incurs to effect a business combination such as legal, due diligence and other closing related costs. Costs directly related to the development of properties are capitalized. Capitalized development costs include interest, internal wages, property taxes, insurance, and other project costs incurred during the period of development. After the determination is made to capitalize a cost, it is allocated to the specific component of a project that is benefited. Determination of when a development project commences and capitalization begins, and when a development project is substantially complete and held available for occupancy and capitalization must cease, involves a degree of judgment. The Company’s capitalization policy on development properties is guided by guidance in ASC 835-20 “Capitalization of Interest” and ASC 970 “Real Estate-General.” The costs of land and buildings under development include specifically identifiable costs. The capitalized costs include pre-construction costs necessary to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. The Company begins the capitalization of costs during the pre-construction period which it defines as activities that are necessary to the development of the property. The Company considers a construction project as substantially completed and held available for occupancy upon the completion of tenant improvements, but no later than one year from cessation of major construction activity. The Company ceases capitalization on the portion (1) substantially completed, (2) occupied or held available for occupancy, and capitalizes only those costs associated with the portion under construction or (3) if activities necessary for the development of the property have been suspended. Interest costs capitalized for the years ended December 31, 2015 , 2014 and 2013 were $34.2 million , $52.5 million and $68.2 million , respectively. Salaries and related costs capitalized for the years ended December 31, 2015 , 2014 and 2013 were $10.4 million , $8.5 million and $7.7 million , respectively. Expenditures for repairs and maintenance are charged to operations as incurred. Significant betterments are capitalized. When assets are sold or retired, their costs and related accumulated depreciation are removed from the accounts with the resulting gains or losses reflected in net income or loss for the period. The Company computes depreciation and amortization on properties using the straight-line method based on estimated useful asset lives. In accordance with ASC 805 “Business Combinations,” the Company allocates the acquisition cost of real estate to its components and depreciates or amortizes these assets (or liabilities) over their useful lives. The amortization of acquired “above-” and “below-market” leases and acquired in-place leases is recorded as an adjustment to revenue and depreciation and amortization, respectively, in the Consolidated Statements of Operations. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows: Land improvements 25 to 40 years Buildings and improvements 10 to 40 years Tenant improvements Shorter of useful life or terms of related lease Furniture, fixtures, and equipment 3 to 7 years
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand and investments with maturities of three months or less from the date of purchase. The majority of the Company’s cash and cash equivalents are held at major commercial banks which may at times exceed the Federal Deposit Insurance Corporation limit of $250,000 . The Company has not experienced any losses to date on its invested cash.
Cash Held in Escrows	Cash Held in Escrows Escrows include amounts established pursuant to various agreements for security deposits, property taxes, insurance and other costs.
Investments in Securities	Investments in Securities The Company accounts for investments in trading securities at fair value, with gains or losses resulting from changes in fair value recognized currently in earnings. The designation of trading securities is generally determined at acquisition. The Company maintains a deferred compensation plan that is designed to allow officers of Boston Properties, Inc. to defer a portion of their current income on a pre-tax basis and receive a tax-deferred return on these deferrals. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2015 and 2014 , the Company had maintained approximately $20.4 million and $19.5 million , respectively, in a separate account, which is not restricted as to its use. The Company recognized gains (losses) of approximately $(0.7) million , $1.0 million and $2.9 million on its investments in the account associated with the Company’s deferred compensation plan during the years ended December 31, 2015 , 2014 and 2013 , respectively.
Tenant and Other Receivables	Tenant and Other Receivables Tenant and other accounts receivable, other than accrued rents receivable, are expected to be collected within one year.
Deferred Charges	Deferred Charges Deferred charges include leasing costs and financing fees. Leasing costs include acquired intangible in-place lease values and direct and incremental fees and costs incurred in the successful negotiation of leases, including brokerage, legal, internal leasing employee salaries and other costs which have been deferred and are being amortized on a straight-line basis over the terms of the respective leases. Internal leasing salaries and related costs capitalized for the years ended December 31, 2015 , 2014 and 2013 were $5.5 million , $6.0 million and $5.1 million , respectively. External fees and costs incurred to obtain long-term financing have been deferred and are being amortized over the terms of the respective loans and are included within interest expense. Unamortized financing and leasing costs are charged to expense upon the early repayment or significant modification of the financing or upon the early termination of the lease, respectively. Fully amortized deferred charges are removed from the books upon the expiration of the lease or maturity of the debt.
Investments in Unconsolidated Joint Ventures	Investments in Unconsolidated Joint Ventures The Company consolidates variable interest entities (“VIEs”) in which it is considered to be the primary beneficiary. VIEs are entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or that the holders of the equity investment at risk do not have a controlling financial interest. The primary beneficiary is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the variable interest entity’s performance, and (2) the obligation to absorb losses and right to receive the returns from the variable interest entity that would be significant to the variable interest entity. For ventures that are not VIEs the Company consolidates entities for which it has significant decision making control over the ventures’ operations. The Company’s judgment with respect to its level of influence or control of an entity involves the consideration of various factors including the form of the Company’s ownership interest, its representation in the entity’s governance, the size of its investment (including loans), estimates of future cash flows, its ability to participate in policy making decisions and the rights of the other investors to participate in the decision making process and to replace the Company as manager and/or liquidate the venture, if applicable. The Company’s assessment of its influence or control over an entity affects the presentation of these investments in the Company’s consolidated financial statements. In addition to evaluating control rights, the Company consolidates entities in which the outside partner has no substantive kick-out rights to remove the Company as the managing member. Accounts of the consolidated entity are included in the accounts of the Company and the noncontrolling interest is reflected on the Consolidated Balance Sheets as a component of equity or in temporary equity between liabilities and equity. Investments in unconsolidated joint ventures are recorded initially at cost, and subsequently adjusted for equity in earnings and cash contributions and distributions. Any difference between the carrying amount of these investments on the balance sheet and the underlying equity in net assets is amortized as an adjustment to equity in earnings of unconsolidated joint ventures over the life of the related asset. Under the equity method of accounting, the net equity investment of the Company is reflected within the Consolidated Balance Sheets, and the Company’s share of net income or loss from the joint ventures is included within the Consolidated Statements of Operations. The joint venture agreements may designate different percentage allocations among investors for profits and losses; however, the Company’s recognition of joint venture income or loss generally follows the joint venture’s distribution priorities, which may change upon the achievement of certain investment return thresholds. The Company may account for cash distributions in excess of its investment in an unconsolidated joint venture as income when the Company is not the general partner in a limited partnership and when the Company has neither the requirement nor the intent to provide financial support to the joint venture. The Company’s investments in unconsolidated joint ventures are reviewed for impairment periodically and the Company records impairment charges when events or circumstances change indicating that a decline in the fair values below the carrying values has occurred and such decline is other-than-temporary. The ultimate realization of the investment in unconsolidated joint ventures is dependent on a number of factors, including the performance of each investment and market conditions. The Company will record an impairment charge if it determines that a decline in the value below the carrying value of an investment in an unconsolidated joint venture is other-than-temporary. To the extent that the Company contributes assets to a joint venture, the Company’s investment in the joint venture is recorded at the Company’s cost basis in the assets that were contributed to the joint venture. To the extent that the Company’s cost basis is different than the basis reflected at the joint venture level, the basis difference is amortized over the life of the related asset and included in the Company’s share of equity in net income of the joint venture. In accordance with the provisions of ASC 970-323 “Investments—Equity Method and Joint Ventures” (“ASC 970-323”), the Company will recognize gains on the contribution of real estate to joint ventures, relating solely to the outside partner’s interest, to the extent the economic substance of the transaction is a sale. The combined summarized financial information of the unconsolidated joint ventures is disclosed in Note 5 .
Revenue Recognition	Revenue Recognition In general, the Company commences rental revenue recognition when the tenant takes possession of the leased space and the leased space is substantially ready for its intended use. Contractual rental revenue is reported on a straight-line basis over the terms of the respective leases. The impact of the straight-line rent adjustment increased revenue by approximately $80.0 million , $63.1 million and $65.8 million for the years ended December 31, 2015 , 2014 and 2013 , respectively, as the revenue recorded exceeded amounts billed. Accrued rental income, as reported on the Consolidated Balance Sheets, represents cumulative rental income earned in excess of rent payments received pursuant to the terms of the individual lease agreements. The Company maintains an allowance against accrued rental income for future potential tenant credit losses. The credit assessment is based on the estimated accrued rental income that is recoverable over the term of the lease. The Company also maintains an allowance for doubtful accounts for estimated losses resulting from the inability of tenants to make required rent payments. The computation of this allowance is based on the tenants’ payment history and current credit status, as well as certain industry or geographic specific credit considerations. If the Company’s estimates of collectability differ from the cash received, then the timing and amount of the Company’s reported revenue could be impacted. The credit risk is mitigated by the high quality of the Company’s existing tenant base, reviews of prospective tenants’ risk profiles prior to lease execution and consistent monitoring of the Company’s portfolio to identify potential problem tenants. In accordance with ASC 805, the Company recognizes acquired in-place “above-” and “below-market” leases at their fair values as rental revenue over the original term of the respective leases. The impact of the acquired in-place “above-” and “below-market” leases increased revenue by approximately $35.9 million , $48.3 million and $28.0 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands). Accrued rental income as reported on the Consolidated Balance Sheets represents rental income recognized in excess of rent payments actually received pursuant to the terms of the individual lease agreements. Acquired Above-Market Lease Intangibles Acquired Below-Market Lease Intangibles 2016 $ 14,210 $ 43,809 2017 11,756 33,112 2018 8,637 31,272 2019 7,106 26,434 2020 5,400 9,852 Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized as revenue in the period during which the expenses are incurred. Tenant reimbursements are recognized and presented in accordance with guidance in ASC 605-45 “Principal Agent Considerations” (“ASC 605-45”). ASC 605-45 requires that these reimbursements be recorded on a gross basis, as the Company is generally the primary obligor with respect to purchasing goods and services from third-party suppliers, has discretion in selecting the supplier and has credit risk. The Company also receives reimbursement of payroll and payroll related costs from third parties which the Company reflects on a net basis. The Company’s parking revenues are derived from leases, monthly parking and transient parking. The Company recognizes parking revenue as earned. The Company’s hotel revenues are derived from room rentals and other sources such as charges to guests for telephone service, movie and vending commissions, meeting and banquet room revenue and laundry services. Hotel revenues are recognized as earned. The Company receives management and development fees from third parties. Property management fees are recorded and earned based on a percentage of collected rents at the properties under management, and not on a straight-line basis, because such fees are contingent upon the collection of rents. The Company records development fees as earned depending on the risk associated with each project. Profit on development fees earned from joint venture projects is recognized as revenue to the extent of the third party partners’ ownership interest. Gains on sales of real estate are recognized pursuant to the provisions included in ASC 360-20 “Real Estate Sales” (“ASC 360-20”). The specific timing of the sale is measured against various criteria in ASC 360-20 related to the terms of the transaction and any continuing involvement in the form of management or financial assistance associated with the properties. If the sales criteria for the full accrual method are not met, the Company defers some or all of the gain recognition and accounts for the continued operations of the property by applying the finance, leasing, profit sharing, deposit, installment or cost recovery methods, as appropriate, until the sales criteria are met.
Ground Leases	Ground Leases The Company has non-cancelable ground lease obligations with various initial term expiration dates through 2114 . The Company recognizes ground rent expense on a straight-line basis over the terms of the respective ground lease agreements. The future contractual minimum lease payments to be made by the Company as of December 31, 2015 , under non-cancelable ground leases which expire on various dates through 2114 , are as follows: Years Ending December 31, (in thousands) 2016 $ 15,188 2017 30,658 2018 11,507 2019 9,693 2020 9,870 Thereafter 594,701 The table includes the Company’s 99 -year ground and air rights lease related to its 200 Clarendon Street property’s adjacent 100 Clarendon Street garage and Back Bay Station concourse level. The Company expects to incur the remaining contractual ground lease payments aggregating approximately $28.9 million over the next three years with no payments thereafter. The Company is recognizing these amounts on a straight-line basis over the 99-year term of the ground and air rights lease (See Note 3).
Earnings Per Share and Earnings Per Common Unit	Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income available to common shareholders, as adjusted for undistributed earnings (if any) of certain securities issued by Boston Properties Limited Partnership, by the weighted average number of shares of Common Stock outstanding during the year. Diluted EPS reflects the potential dilution that could occur from shares issuable in connection with awards under stock-based compensation plans, including upon the exercise of stock options, and securities of Boston Properties Limited Partnership that are exchangeable for Common Stock. Earnings Per Common Unit Basic earnings per common unit is computed by dividing net income available to common unitholders, as adjusted for undistributed earnings (if any) of certain securities issued by Boston Properties Limited Partnership, by the weighted average number of common units outstanding during the year. Diluted earnings per common unit reflects the potential dilution that could occur from units issuable in connection with awards under Boston Properties, Inc.’s stock-based compensation plans, including upon the exercise of stock options, and conversion of preferred units of Boston Properties Limited Partnership.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying values of cash and cash equivalents, marketable securities, escrows, receivables, accounts payable, accrued expenses and other assets and liabilities are reasonable estimates of their fair values because of the short maturities of these instruments. The Company follows the authoritative guidance for fair value measurements when valuing its financial instruments for disclosure purposes. Boston Properties Limited Partnership determines the fair value of its unsecured senior notes using market prices. The inputs used in determining the fair value of Boston Properties Limited Partnership’s unsecured 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 it uses quoted market rates to value these instruments. However, the inputs used in determining the fair value could be categorized at a level 2 basis if trading volumes are low. The Company determines the fair value of its mortgage notes payable using discounted cash flow analyses by discounting the spread between the future contractual interest payments and hypothetical future interest payments on mortgage debt based on current market rates for similar securities. In determining the current market rates, the Company adds its estimates of market spreads to the quoted yields on federal government treasury securities with similar maturity dates to its debt. The inputs used in determining the fair value of the Company’s mortgage notes payable and mezzanine notes payable are categorized at a level 3 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company considers the rates used in the valuation techniques to be unobservable inputs. Because the Company’s valuations of its financial instruments are based on these types of estimates, the actual fair values of its financial instruments may differ materially if the Company’s estimates do not prove to be accurate. The following table presents the aggregate carrying value of the Company’s indebtedness and the Company’s corresponding estimate of fair value as of December 31, 2015 and December 31, 2014 (in thousands): December 31, 2015 December 31, 2014 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Mortgage notes payable $ 3,438,714 $ 3,503,746 $ 4,309,484 $ 4,449,541 Mezzanine notes payable 308,482 306,103 309,796 306,156 Unsecured senior notes 5,289,317 5,547,738 5,287,704 5,645,819 Total $ 9,036,513 $ 9,357,587 $ 9,906,984 $ 10,401,516
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Derivative instruments and hedging activities require management to make judgments on the nature of its derivatives and their effectiveness as hedges. These judgments determine if the changes in fair value of the derivative instruments are reported in the Consolidated Statements of Operations as a component of net income or as a component of comprehensive income and as a component of equity on the Consolidated Balance Sheets. While management believes its judgments are reasonable, a change in a derivative’s effectiveness as a hedge could materially affect expenses, net income and equity. The Company accounts for the effective portion of changes in the fair value of a derivative in other comprehensive income (loss) and subsequently reclassifies the effective portion to earnings over the term that the hedged transaction affects earnings. The Company accounts for the ineffective portion of changes in the fair value of a derivative directly in earnings.
Stock-Based Employee Compensation Plans	Stock-Based Employee Compensation Plans At December 31, 2015 , the Company has a stock-based employee compensation plan. Effective January 1, 2005, the Company adopted early ASC 718 “Compensation – Stock Compensation” (“ASC 718”), which revised the fair value based method of accounting for share-based payment liabilities, forfeitures and modifications of stock-based awards and clarified previous guidance in several areas, including measuring fair value, classifying an award as equity or as a liability and attributing compensation cost to reporting periods.
Use of Estimatesin the Preperation of Financial Statements	Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. These estimates include such items as depreciation and allowances for doubtful accounts. Actual results could differ from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements On April 10, 2014, the FASB issued ASU 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity” (“ASU 2014-08”). ASU 2014-08 clarifies that discontinued operations presentation applies only to disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results (e.g., a disposal of a major geographical area, a major line of business, a major equity method investment or other major parts of an entity). ASU 2014-08 is effective prospectively for reporting periods beginning after December 15, 2014. Early adoption is permitted, and the Company early adopted ASU 2014-08 during the first quarter of 2014. The Company’s adoption of ASU 2014-08 resulted in the operating results and gains on sales of real estate from the operating properties sold during the years ended December 31, 2015 and 2014 not being reflected as Discontinued Operations in the Company’s Consolidated Statements of Operations (See Note 3 ). In February 2015, the FASB issued ASU 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis” (“ASU 2015-02”). ASU 2015-02 affects reporting entities that are required to evaluate whether they should consolidate certain legal entities. ASU 2015-02 modifies the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities, eliminates the presumption that a general partner should consolidate a limited partnership and affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. ASU 2015-02 is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. A reporting entity may apply the amendments in ASU 2015-02 using: (a) a modified retrospective approach by recording a cumulative-effect adjustment to equity as of the beginning of the fiscal year of adoption; or (b) by applying the amendments retrospectively. The Company expects that its consolidated joint ventures will be considered VIEs thus requiring additional disclosures beginning in the first quarter of 2016. The adoption of ASU 2015-02 will not have a material impact on the Company’s consolidated financial statements. In April 2015, the FASB issued ASU 2015-03, “Simplifying the Presentation of Debt Issuance Costs” (“ASU 2015-03”), which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs is not affected. ASU 2015-03 is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years and shall be applied on a retrospective basis, wherein the balance sheet of each individual period presented should be adjusted to reflect the period-specific effects of applying the new guidance. Early adoption was permitted for financial statements that have not been previously issued. The adoption of ASU 2015-03 will not have a material impact on the Company’s consolidated financial statements. In January 2016, the FASB issued ASU 2016-01, “Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities” (“ASU 2016-01”). ASU 2016-01 requires equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income, requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset, and eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost. ASU 2016-01 is effective for fiscal years beginning October 1, 2018. Early application is permitted. The Company is currently assessing the potential impact that the adoption of ASU 2016-01 will have on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, “ Leases ” (“ASU 2016-02”) , which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). ASU 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. ASU 2016-02 is expected to impact the Company’s consolidated financial statements as the Company has certain operating land lease arrangements for which it is the lessee. ASU 2016-02 supersedes previous leasing standards . ASU 2016-02 is effective for the Company for reporting periods beginning after December 15, 2018, with early adoption permitted. The Company is currently assessing the potential impact that the adoption of ASU 2016-02 will have on its consolidated financial statements.
Equity Offering Costs	Equity Offering Costs Underwriting commissions and offering costs have been reflected as a reduction of additional paid-in capital
Treasury Stock	Treasury Stock Boston Properties, Inc.’s share repurchases are reflected as treasury stock utilizing the cost method of accounting and are presented as a reduction to consolidated stockholders’ equity.
Dividends	Dividends Earnings and profits, which determine the taxability of dividends to stockholders, will differ from income reported for financial reporting purposes due to the differences for federal income tax purposes in the treatment of gains/losses on the sale of real property, revenue and expense recognition, compensation expense, and in the estimated useful lives and basis used to compute depreciation. The tax treatment of common dividends per share for federal income tax purposes is as follows: For the year ended December 31, 2015 2014 2013 Per Share % Per Share % Per Share % Ordinary income $ 2.34 57.97 % $ — — % $ 2.31 48.71 % Capital gain income 1.70 42.03 % 6.82 100.00 % 2.44 51.29 % Total $ 4.04 (1) 100.00 % $ 6.82 (2) 100.00 % $ 4.75 (3) 100.00 % _____________ (1) The fourth quarter 2015 dividend of $1.90 per common share consists of a $1.25 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $1.35 per common share was allocable to 2015 and approximately $0.55 per common share is allocable to 2016. (2) The fourth quarter 2014 dividend of $5.15 per common share consists of a $4.50 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $4.41 per common share was allocable to 2014 and approximately $0.74 per common share is allocable to 2015. (3) The fourth quarter 2013 dividend of $2.90 per common share consists of a $2.25 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $2.44 per common share was allocable to 2013 and approximately $0.46 per common share is allocable to 2014.
Income Taxes	Income Taxes Boston Properties, Inc. has elected to be treated as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “Code”), commencing with its taxable year ended December 31, 1997. As a result, it generally will not be subject to federal corporate income tax on its taxable income that is distributed to its stockholders. A REIT is subject to a number of organizational and operational requirements, including a requirement that it currently distribute at least 90% of its annual taxable income (with certain adjustments). Boston Properties, Inc.’s policy is to distribute at least 100% of its taxable income. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to Boston Properties, Inc.’s consolidated taxable REIT subsidiaries. Boston Properties, Inc.’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. Boston Properties, Inc. has no uncertain tax positions recognized as of December 31, 2015 and 2014 . The Company owns a hotel property which is managed through a taxable REIT subsidiary. The hotel taxable REIT subsidiary, a wholly owned subsidiary of Boston Properties Limited Partnership, is the lessee pursuant to the lease for the hotel property. As lessor, Boston Properties Limited Partnership is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of the existing management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, Boston Properties, Inc. has recorded a tax provision in its Consolidated Statements of Operations for the years ended December 31, 2015 , 2014 and 2013 . The net difference between the tax basis and the reported amounts of Boston Properties, Inc.’s assets and liabilities is approximately $1.6 billion and $2.2 billion as of December 31, 2015 and 2014 , respectively, which is primarily related to the difference in basis of contributed property and accrued rental income. Certain entities included in Boston Properties, Inc.’s consolidated financial statements are subject to certain state and local taxes. These taxes are recorded as operating expenses in the accompanying consolidated financial statements. The following table reconciles GAAP net income attributable to Boston Properties, Inc. to taxable income: For the year ended December 31, 2015 2014 2013 (in thousands) Net income attributable to Boston Properties, Inc. $ 583,106 $ 443,611 $ 749,811 Straight-line rent and net “above-” and “below-market” rent adjustments (92,483 ) (91,733 ) (74,445 ) Book/Tax differences from depreciation and amortization 307,115 239,681 170,370 Book/Tax differences from interest expense (43,349 ) (43,148 ) (7,912 ) Book/Tax differences on gains/(losses) from capital transactions (74,482 ) 943,778 (1) (124,413 ) Book/Tax differences from stock-based compensation 22,008 32,483 42,146 Tangible Property Regulations (2) (74,887 ) (442,650 ) — Other book/tax differences, net (15,259 ) (7,945 ) (4,885 ) Taxable income $ 611,769 $ 1,074,077 $ 750,672 __________ (1) Consists primarily of the gain on sale of real estate for tax purposes related to the October 2014 sale by the Company of a 45% interest in each of 601 Lexington Avenue in New York City and Atlantic Wharf Office Building and 100 Federal Street in Boston, which was accounted for as an equity transaction for GAAP purposes with no gain on sale of real estate recognized. (2) In September 2013, the Internal Revenue Service released final Regulations governing when taxpayers like Boston Properties, Inc. must capitalize and depreciate costs for acquiring, maintaining, repairing and replacing tangible property and when taxpayers can deduct such costs. These final Regulations were effective for tax years beginning on or after January 1, 2014. These Regulations permitted Boston Properties, Inc. to deduct certain types of expenditures that were previously required to be capitalized. The Regulations also allowed Boston Properties, Inc. to make a one -time election in 2014 to immediately deduct certain amounts that were capitalized in previous years that are not required to be capitalized under the new Regulations. The one -time deduction included above totaled approximately $385.6 million for the year ended December 31, 2014. Boston Properties Limited Partnership Income Taxes The partners are required to report their respective share of Boston Properties Limited Partnership’s taxable income or loss on their respective tax returns and are liable for any related taxes thereon. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to Boston Properties Limited Partnership's consolidated taxable REIT subsidiaries. Boston Properties Limited Partnership’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. Boston Properties Limited Partnership has no uncertain tax positions recognized as of December 31, 2015 and 2014 . The Company owns a hotel property which is managed through a taxable REIT subsidiary. The hotel taxable REIT subsidiary, a wholly owned subsidiary Boston Properties Limited Partnership, is the lessee pursuant to the lease for the hotel property. As lessor, Boston Properties Limited Partnership is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of the existing management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, Boston Properties Limited Partnership has recorded a tax provision in its Consolidated Statements of Operations for the years ended December 31, 2015 , 2014 and 2013 . The net difference between the tax basis and the reported amounts of Boston Properties Limited Partnership’s assets and liabilities is approximately $2.6 billion and $1.4 billion as of December 31, 2015 and 2014 , respectively, which is primarily related to the difference in basis of contributed property and accrued rental income. Certain entities included in Boston Properties Limited Partnership’s consolidated financial statements are subject to certain state and local taxes. These taxes are recorded as operating expenses in the accompanying consolidated financial statements. The following table reconciles GAAP net income attributable to Boston Properties Limited Partnership to taxable income: For the year ended December 31, 2015 2014 2013 (in thousands) Net income attributable to Boston Properties Limited Partnership $ 659,248 $ 509,629 $ 849,573 Straight-line rent and net “above-” and “below-market” rent adjustments (103,227 ) (102,319 ) (82,904 ) Book/Tax differences from depreciation and amortization 329,629 253,590 174,384 Book/Tax differences from interest expense (48,385 ) (48,128 ) (8,811 ) Book/Tax differences on gains/(losses) from capital transactions (67,602 ) 1,065,518 (1) (138,300 ) Book/Tax differences from stock-based compensation 24,565 36,232 46,935 Tangible Property Regulations (2) (83,587 ) (493,731 ) — Other book/tax differences, net (14,561 ) (11,403 ) 8,589 Taxable income $ 696,080 $ 1,209,388 $ 849,466 __________ (1) Consists primarily of the gain on sale of real estate for tax purposes related to the October 2014 sale by the Company of a 45% interest in each of 601 Lexington Avenue in New York City and Atlantic Wharf Office Building and 100 Federal Street in Boston, which was accounted for as an equity transaction for GAAP purposes with no gain on sale of real estate recognized. (2) In September 2013, the Internal Revenue Service released final Regulations governing when taxpayers like Boston Properties Limited Partnership must capitalize and depreciate costs for acquiring, maintaining, repairing and replacing tangible property and when taxpayers can deduct such costs. These final Regulations were effective for tax years beginning on or after January 1, 2014. These Regulations permitted Boston Properties Limited Partnership to deduct certain types of expenditures that were previously required to be capitalized. The Regulations also allowed Boston Properties Limited Partnership to make a one -time election in 2014 to immediately deduct certain amounts that were capitalized in previous years that are not required to be capitalized under the new Regulations. The one -time deduction included above totaled approximately $430.1 million for the year ended December 31, 2014.

Summary Of Significant Accoun31

Summary Of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment [Table Text Block]	Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows: Land improvements 25 to 40 years Buildings and improvements 10 to 40 years Tenant improvements Shorter of useful life or terms of related lease Furniture, fixtures, and equipment 3 to 7 years
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands). Accrued rental income as reported on the Consolidated Balance Sheets represents rental income recognized in excess of rent payments actually received pursuant to the terms of the individual lease agreements. Acquired Above-Market Lease Intangibles Acquired Below-Market Lease Intangibles 2016 $ 14,210 $ 43,809 2017 11,756 33,112 2018 8,637 31,272 2019 7,106 26,434 2020 5,400 9,852 The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands). Acquired In-Place Lease Intangibles 2016 $ 52,456 2017 36,438 2018 31,913 2019 26,067 2020 13,325
Schedule Of Future Contractual Minimum Lease Payments Under Non-Cancelable Ground Leases [Table Text Block]	The future contractual minimum lease payments to be made by the Company as of December 31, 2015 , under non-cancelable ground leases which expire on various dates through 2114 , are as follows: Years Ending December 31, (in thousands) 2016 $ 15,188 2017 30,658 2018 11,507 2019 9,693 2020 9,870 Thereafter 594,701 The table includes the Company’s 99 -year ground and air rights lease related to its 200 Clarendon Street property’s adjacent 100 Clarendon Street garage and Back Bay Station concourse level. The Company expects to incur the remaining contractual ground lease payments aggregating approximately $28.9 million over the next three years with no payments thereafter. The Company is recognizing these amounts on a straight-line basis over the 99-year term of the ground and air rights lease (See Note 3).
Fair Value, by Balance Sheet Grouping [Table Text Block]	The following table presents the aggregate carrying value of the Company’s indebtedness and the Company’s corresponding estimate of fair value as of December 31, 2015 and December 31, 2014 (in thousands): December 31, 2015 December 31, 2014 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Mortgage notes payable $ 3,438,714 $ 3,503,746 $ 4,309,484 $ 4,449,541 Mezzanine notes payable 308,482 306,103 309,796 306,156 Unsecured senior notes 5,289,317 5,547,738 5,287,704 5,645,819 Total $ 9,036,513 $ 9,357,587 $ 9,906,984 $ 10,401,516
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes, Table [Table Text Block]	The tax treatment of common dividends per share for federal income tax purposes is as follows: For the year ended December 31, 2015 2014 2013 Per Share % Per Share % Per Share % Ordinary income $ 2.34 57.97 % $ — — % $ 2.31 48.71 % Capital gain income 1.70 42.03 % 6.82 100.00 % 2.44 51.29 % Total $ 4.04 (1) 100.00 % $ 6.82 (2) 100.00 % $ 4.75 (3) 100.00 % _____________ (1) The fourth quarter 2015 dividend of $1.90 per common share consists of a $1.25 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $1.35 per common share was allocable to 2015 and approximately $0.55 per common share is allocable to 2016. (2) The fourth quarter 2014 dividend of $5.15 per common share consists of a $4.50 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $4.41 per common share was allocable to 2014 and approximately $0.74 per common share is allocable to 2015. (3) The fourth quarter 2013 dividend of $2.90 per common share consists of a $2.25 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $2.44 per common share was allocable to 2013 and approximately $0.46 per common share is allocable to 2014.
Gaap Reconciliation Of Net Income To Taxable Income, Table [Table Text Block]	The following table reconciles GAAP net income attributable to Boston Properties, Inc. to taxable income: For the year ended December 31, 2015 2014 2013 (in thousands) Net income attributable to Boston Properties, Inc. $ 583,106 $ 443,611 $ 749,811 Straight-line rent and net “above-” and “below-market” rent adjustments (92,483 ) (91,733 ) (74,445 ) Book/Tax differences from depreciation and amortization 307,115 239,681 170,370 Book/Tax differences from interest expense (43,349 ) (43,148 ) (7,912 ) Book/Tax differences on gains/(losses) from capital transactions (74,482 ) 943,778 (1) (124,413 ) Book/Tax differences from stock-based compensation 22,008 32,483 42,146 Tangible Property Regulations (2) (74,887 ) (442,650 ) — Other book/tax differences, net (15,259 ) (7,945 ) (4,885 ) Taxable income $ 611,769 $ 1,074,077 $ 750,672 __________ (1) Consists primarily of the gain on sale of real estate for tax purposes related to the October 2014 sale by the Company of a 45% interest in each of 601 Lexington Avenue in New York City and Atlantic Wharf Office Building and 100 Federal Street in Boston, which was accounted for as an equity transaction for GAAP purposes with no gain on sale of real estate recognized. (2) In September 2013, the Internal Revenue Service released final Regulations governing when taxpayers like Boston Properties, Inc. must capitalize and depreciate costs for acquiring, maintaining, repairing and replacing tangible property and when taxpayers can deduct such costs. These final Regulations were effective for tax years beginning on or after January 1, 2014. These Regulations permitted Boston Properties, Inc. to deduct certain types of expenditures that were previously required to be capitalized. The Regulations also allowed Boston Properties, Inc. to make a one -time election in 2014 to immediately deduct certain amounts that were capitalized in previous years that are not required to be capitalized under the new Regulations. The one -time deduction included above totaled approximately $385.6 million for the year ended December 31, 2014.
Boston Properties Limited Partnership [Member]
Summary Of Significant Accounting Policies [Line Items]
Gaap Reconciliation Of Net Income To Taxable Income, Table [Table Text Block]	The following table reconciles GAAP net income attributable to Boston Properties Limited Partnership to taxable income: For the year ended December 31, 2015 2014 2013 (in thousands) Net income attributable to Boston Properties Limited Partnership $ 659,248 $ 509,629 $ 849,573 Straight-line rent and net “above-” and “below-market” rent adjustments (103,227 ) (102,319 ) (82,904 ) Book/Tax differences from depreciation and amortization 329,629 253,590 174,384 Book/Tax differences from interest expense (48,385 ) (48,128 ) (8,811 ) Book/Tax differences on gains/(losses) from capital transactions (67,602 ) 1,065,518 (1) (138,300 ) Book/Tax differences from stock-based compensation 24,565 36,232 46,935 Tangible Property Regulations (2) (83,587 ) (493,731 ) — Other book/tax differences, net (14,561 ) (11,403 ) 8,589 Taxable income $ 696,080 $ 1,209,388 $ 849,466 __________ (1) Consists primarily of the gain on sale of real estate for tax purposes related to the October 2014 sale by the Company of a 45% interest in each of 601 Lexington Avenue in New York City and Atlantic Wharf Office Building and 100 Federal Street in Boston, which was accounted for as an equity transaction for GAAP purposes with no gain on sale of real estate recognized. (2) In September 2013, the Internal Revenue Service released final Regulations governing when taxpayers like Boston Properties Limited Partnership must capitalize and depreciate costs for acquiring, maintaining, repairing and replacing tangible property and when taxpayers can deduct such costs. These final Regulations were effective for tax years beginning on or after January 1, 2014. These Regulations permitted Boston Properties Limited Partnership to deduct certain types of expenditures that were previously required to be capitalized. The Regulations also allowed Boston Properties Limited Partnership to make a one -time election in 2014 to immediately deduct certain amounts that were capitalized in previous years that are not required to be capitalized under the new Regulations. The one -time deduction included above totaled approximately $430.1 million for the year ended December 31, 2014.

Real Estate (Tables)

Real Estate (Tables)	12 Months Ended
	Dec. 31, 2015
Real Estate Properties [Line Items]
Schedule of Property Subject to or Available for Operating Lease [Table Text Block]	Boston Properties, Inc. Real estate consisted of the following at December 31 (in thousands): 2015 2014 Land $ 4,806,021 $ 4,785,772 Land held for future development 252,195 268,114 Buildings and improvements 11,709,285 11,666,105 Tenant improvements 1,920,247 1,752,115 Furniture, fixtures and equipment 29,852 27,986 Construction in progress 763,935 736,311 Total 19,481,535 19,236,403 Less: Accumulated depreciation (3,925,894 ) (3,547,659 ) $ 15,555,641 $ 15,688,744 Boston Properties Limited Partnership Real estate consisted of the following at December 31 (in thousands): 2015 2014 Land $ 4,700,793 $ 4,680,181 Land held for future development 252,195 268,114 Buildings and improvements 11,394,119 11,349,851 Tenant improvements 1,920,247 1,752,115 Furniture, fixtures and equipment 29,852 27,986 Construction in progress 763,935 736,311 Total 19,061,141 18,814,558 Less: Accumulated depreciation (3,846,816 ) (3,476,321 ) $ 15,214,325 $ 15,338,237
Summary Of The Discontinued Operations	The following table summarizes the income from discontinued operations related to One Preserve Parkway, 10 & 20 Burlington Mall Road, 1301 New York Avenue, 303 Almaden Boulevard and Montvale Center and the related gains on sales of real estate, gain on forgiveness of debt and impairment loss for the year ended December 31, 2013: Boston Properties, Inc. For the year ended December 31, 2013 (in thousands) Total revenue $ 20,138 Expenses Operating 6,996 Depreciation and amortization 4,760 Total expenses 11,756 Operating income 8,382 Other expense Interest expense 360 Income from discontinued operations $ 8,022 Noncontrolling interest in income from discontinued operations – common units of the Operating Partnership (803 ) Income from discontinued operations attributable to Boston Properties, Inc. $ 7,219 Gains on sales of real estate from discontinued operations $ 112,829 Gain on forgiveness of debt from discontinued operations 20,182 Impairment loss from discontinued operations (3,241 ) Noncontrolling interest in gains on sales of real estate, gain on forgiveness of debt and impairment loss from discontinued operations – common units of the Operating Partnership (13,348 ) Gains on sales of real estate, gain on forgiveness of debt and impairment loss from discontinued operations attributable to Boston Properties, Inc. $ 116,422 Boston Properties Limited Partnership For the year ended December 31, 2013 (in thousands) Total revenue $ 20,138 Expenses Operating 6,996 Depreciation and amortization 4,760 Total expenses 11,756 Operating income 8,382 Other expense Interest expense 360 Income from discontinued operations attributable to Boston Properties Limited Partnership $ 8,022 Gains on sales of real estate from discontinued operations attributable to Boston Properties Limited Partnership $ 115,459 Gain on forgiveness of debt from discontinued operations attributable to Boston Properties Limited Partnership $ 20,736 Impairment loss from discontinued operations attributable to Boston Properties Limited Partnership $ (2,852 )
Pro Forma In Connection With Acquisition	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. Additional information for these transactions are provided below. Boston Properties, Inc. Pro Forma (Unaudited) Year ended December 31, 2013 (in thousands, except per share data) Total revenue $ 2,257,098 Income from continuing operations $ 302,354 Net income attributable to Boston Properties, Inc. $ 400,017 Basic earnings per share: Net income per share attributable to Boston Properties, Inc. $ 2.58 Diluted earnings per share: Net income per share attributable to Boston Properties, Inc. $ 2.57 Boston Properties Limited Partnership Pro Forma (Unaudited) Year ended December 31, 2013 (in thousands, except per unit data) Total revenue $ 2,257,098 Income from continuing operations $ 314,307 Net income attributable to Boston Properties Limited Partnership $ 452,813 Basic earnings per unit: Net income per unit attributable to Boston Properties Limited Partnership $ 2.68 Diluted earnings per unit: Net income per unit attributable to Boston Properties Limited Partnership $ 2.67
Mountain View Research And Technology Parks [Member]
Real Estate Properties [Line Items]
Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition	The following table summarizes the allocation of the aggregate purchase price of Mountain View Research Park and Mountain View Technology Park at the date of acquisition (in thousands) in accordance with the guidance in ASC 805 “Business Combinations.” Land $ 126,521 Building and improvements 82,451 Tenant improvements 7,326 In-place lease intangibles 23,279 Above-market rents 843 Below-market rents (7,336 ) Net assets acquired $ 233,084
767 Fifth Avenue (the General Motors Building)
Real Estate Properties [Line Items]
Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition	The following table summarizes the allocation of the aggregate purchase price of 767 Fifth Avenue (the General Motors Building) at the date of consolidation on May 31, 2013 (in thousands) in accordance with the guidance in ASC 805 “Business Combinations.” Real estate and related intangibles recorded upon consolidation Land $ 1,796,252 Building and improvements 1,447,446 Tenant improvements 85,208 In-place lease intangibles 357,781 Above market rents 101,897 Below market rents (239,641 ) Above market assumed debt adjustments (192,943 ) $ 3,356,000 Debt recorded upon consolidation Mortgage notes payable $ (1,300,000 ) Mezzanine notes payable (306,000 ) Members’ notes payable (450,000 ) (1) $ (2,056,000 ) Working capital recorded upon consolidation Cash and cash equivalents $ 79,468 Cash held in escrows 2,403 Tenant and other receivables 7,104 Prepaid expenses and other assets 4,269 Accounts payable and accrued expenses (2,418 ) Accrued interest payable (182,369 ) (2) Other liabilities (6,304 ) $ (97,847 ) Noncontrolling interest recorded upon consolidation Noncontrolling interests $ (520,000 ) Noncontrolling interests - working capital 39,139 $ (480,861 ) Net assets recorded upon consolidation $ 721,292 _______________ (1) The Company’s member loan totaling $270.0 million eliminates in consolidation. (2) The Company’s share of the accrued interest payable on the members’ loans totaling approximately $105.5 million eliminates in consolidation.

Deferred Charges (Tables)

Deferred Charges (Tables)	12 Months Ended
	Dec. 31, 2015
Deferred Charges [Abstract]
Deferred Charges	Deferred charges consisted of the following at December 31 (in thousands): 2015 2014 Leasing costs, including lease related intangibles $ 1,123,105 $ 1,234,192 Financing costs 61,402 69,127 1,184,507 1,303,319 Less: Accumulated amortization (451,670 ) (471,575 ) $ 732,837 $ 831,744
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands). Accrued rental income as reported on the Consolidated Balance Sheets represents rental income recognized in excess of rent payments actually received pursuant to the terms of the individual lease agreements. Acquired Above-Market Lease Intangibles Acquired Below-Market Lease Intangibles 2016 $ 14,210 $ 43,809 2017 11,756 33,112 2018 8,637 31,272 2019 7,106 26,434 2020 5,400 9,852 The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands). Acquired In-Place Lease Intangibles 2016 $ 52,456 2017 36,438 2018 31,913 2019 26,067 2020 13,325

Investments in Unconsolidated34

Investments in Unconsolidated Joint Ventures (Tables)	12 Months Ended
	Dec. 31, 2015
Investments In Unconsolidated Joint Ventures [Abstract]
Investments In Unconsolidated Joint Ventures	The investments in unconsolidated joint ventures consist of the following at December 31, 2015 and 2014: Carrying Value of Investment (1) Entity Properties Nominal % Ownership December 31, December 31, (in thousands) Square 407 Limited Partnership Market Square North 50.0 % $ (9,951 ) $ (8,022 ) The Metropolitan Square Associates LLC Metropolitan Square 51.0 % 9,179 8,539 BP/CRF 901 New York Avenue LLC 901 New York Avenue 25.0 % (2) (11,958 ) (1,080 ) WP Project Developer LLC Wisconsin Place Land and Infrastructure 33.3 % (3) 43,524 45,514 Annapolis Junction NFM, LLC Annapolis Junction 50.0 % (4) 29,009 25,246 540 Madison Venture LLC 540 Madison Avenue 60.0 % 68,983 68,128 500 North Capitol LLC 500 North Capitol Street, NW 30.0 % (3,292 ) (2,250 ) 501 K Street LLC 1001 6th Street 50.0 % (5) 42,584 41,736 Podium Developer LLC The Hub on Causeway 50.0 % 18,508 4,231 1265 Main Office JV LLC 1265 Main Street 50.0 % 11,916 N/A BNY Tower Holdings LLC Dock72 at the Brooklyn Navy Yard 50.0 % 11,521 N/A $ 210,023 $ 182,042 _______________ (1) Investments with deficit balances aggregating approximately $25.2 million and $11.4 million at December 31, 2015 and 2014, respectively, have been reflected within Other Liabilities on the Company's Consolidated Balance Sheets. (2) The Company’s economic ownership has increased based on the achievement of certain return thresholds. (3) The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land, parking garage and infrastructure of the project. (4) The joint venture owns four in-service buildings and two undeveloped land parcels. (5) Under the joint venture agreement, the partner may be entitled to up to two additional payments from the venture based on increases in total square footage of the project above 520,000 square feet and achieving certain project returns at stabilization.
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: December 31, December 31, (in thousands) ASSETS Real estate and development in process, net $ 1,072,412 $ 1,034,552 Other assets 256,055 264,097 Total assets $ 1,328,467 $ 1,298,649 LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY Mortgage and notes payable $ 833,895 $ 830,075 Other liabilities 44,549 34,211 Members’/Partners’ equity 450,023 434,363 Total liabilities and members’/partners’ equity $ 1,328,467 $ 1,298,649 Company’s share of equity $ 237,070 $ 209,828 Basis differentials (1) (27,047 ) (27,786 ) Carrying value of the Company’s investments in unconsolidated joint ventures (2) $ 210,023 $ 182,042 _______________ (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. (2) Investments with deficit balances aggregating approximately $25.2 million and $11.4 million at December 31, 2015 and 2014 , respectively, have been reflected within Other Liabilities on the Company's Consolidated Balance Sheets.
Statements Of Operations Of The Joint Ventures	The combined summarized statements of operations of the Company’s joint ventures are as follows: For the year ended December 31, 2015 2014 2013 (in thousands) Total revenue (1) $ 155,642 $ 158,161 $ 311,548 Expenses Operating 65,093 62,974 105,319 Depreciation and amortization 36,057 37,041 86,088 Total expenses 101,150 100,015 191,407 Operating income 54,492 58,146 120,141 Other income (expense) Interest expense (32,176 ) (31,896 ) (112,535 ) Losses from early extinguishments of debt — — (1,677 ) Income from continuing operations 22,316 26,250 5,929 Gains on sales of real estate — — 14,207 Net income $ 22,316 $ 26,250 $ 20,136 Company’s share of net income $ 22,031 (2) $ 11,913 $ 4,612 Gains on sales of real estate — — 54,501 Basis differential 739 856 (1,017 ) Elimination of inter-entity interest on partner loan — — 16,978 Income from unconsolidated joint ventures $ 22,770 $ 12,769 $ 75,074 Gains on consolidation of joint ventures $ — $ — $ 385,991 _______________ (1) Includes straight-line rent adjustments of $3.9 million , $3.0 million and $7.8 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. Includes net above-/below-market rent adjustments of $(0.2) million , $(0.1) million and $33.7 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. (2) During the year ended December 31, 2015, the Company received a distribution of approximately $24.5 million , which was generated from the excess loan proceeds from the refinancing of 901 New York Avenue’s mortgage loan to a new 10 -year mortgage loan totaling $225.0 million . The Company’s allocation of income and distributions for the year ended December 31 2015 was not proportionate to its nominal ownership interest as a result of the achievement of specified investment return thresholds, as provided for in the joint venture agreement.

Mortgage Notes Payable Schedule

Mortgage Notes Payable Schedule of Aggregate Principal Payments On Mortgage Notes (Tables)	12 Months Ended
	Dec. 31, 2015
Mortgage Notes Payable [Abstract]
Schedule of Aggregate Principal Payments On Mortgage Notes [Table Text Block]	Contractual aggregate principal payments of mortgage notes payable at December 31, 2015 are as follows: Principal Payments (in thousands) 2016 $ 576,864 2017 2,067,654 2018 18,633 2019 19,670 2020 20,766 Thereafter 654,892 Total aggregate principal payments 3,358,479 Unamortized balance of historical fair value adjustments 80,235 Total carrying value of mortgage notes payable $ 3,438,714

Derivative and Hedging Instru36

Derivative and Hedging Instruments Derivatives and Hedging Activities Notional Table (Tables)	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]	Boston Properties Limited Partnership’s and 767 Fifth Avenue Partners LLC’s interest rate swap contracts consisted of the following at December 31, 2015 (dollars in thousands): Derivative Instrument Aggregate Notional Amount Effective Date Maturity Date Strike Rate Range Balance Sheet Location Fair Value Low High Boston Properties Limited Partnership: Interest Rate Swaps $ 400,000 September 1, 2016 September 1, 2026 2.348 % - 2.571 % Other Liabilities $ (5,419 ) Interest Rate Swaps 150,000 September 1, 2016 September 1, 2026 2.129 % - 2.325 % Prepaid Expenses and Other Assets 1,188 $ 550,000 $ (4,231 ) 767 Fifth Partners LLC: Interest Rate Swaps $ 250,000 June 7, 2017 June 7, 2027 2.677 % - 2.950 % Other Liabilities $ (7,247 ) Interest Rate Swaps 150,000 June 7, 2017 June 7, 2027 2.336 % - 2.430 % Prepaid Expenses and Other Assets 1,176 $ 400,000 $ (6,071 ) $ 950,000 $ (10,302 )
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table presents the location in the financial statements of the losses recognized related to the Company’s cash flow hedges for the years ended December 31, 2015 , 2014 and 2013 : Year ended December 31, 2015 2014 2013 (in thousands) Amount of loss related to the effective portion recognized in other comprehensive loss $ (10,302 ) $ — $ — Amount of loss related to the effective portion subsequently reclassified to earnings (1) $ (2,510 ) $ (2,508 ) $ (2,513 ) Amount of gain (loss) related to the ineffective portion and amount excluded from effectiveness testing $ — $ — $ — ___________ (1) Consists of amounts from interest rate hedging programs entered into prior to 2015.
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Boston Properties, Inc. The following table reflects the changes in accumulated other comprehensive loss for Boston Properties, Inc. for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ (13,817 ) Amortization of interest rate contracts (1) 2,513 Other comprehensive income attributable to noncontrolling interests (252 ) Balance at December 31, 2013 (11,556 ) Amortization of interest rate contracts (1) 2,508 Other comprehensive income attributable to noncontrolling interests (256 ) Balance at December 31, 2014 (9,304 ) Effective portion of interest rate contracts (10,302 ) Amortization of interest rate contracts (1) 2,510 Other comprehensive loss attributable to noncontrolling interests 2,982 Balance at December 31, 2015 $ (14,114 ) ___________ (1)
Boston Properties Limited Partnership [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Boston Properties Limited Partnership The following table reflects the changes in accumulated other comprehensive loss for Boston Properties Limited Partnership for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ (17,994 ) Amortization of interest rate contracts (1) 2,513 Balance at December 31, 2013 (15,481 ) Amortization of interest rate contracts (1) 2,508 Balance at December 31, 2014 (12,973 ) Effective portion of interest rate contracts (10,302 ) Amortization of interest rate contracts (1) 2,510 Other comprehensive loss attributable to noncontrolling interests in property partnership 2,428 Balance at December 31, 2015 $ (18,337 ) ___________ (1) Consists of amounts from interest rate hedging programs entered into prior to 2015.

Unsecured Senior Notes (Tables)

Unsecured Senior Notes (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Schedule of Senior Notes	The following summarizes the unsecured senior notes outstanding as of December 31, 2015 (dollars in thousands) (See also Note 20 ): Coupon/ Stated Rate Effective Rate(1) Principal Amount Maturity Date(2) 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 5,300,000 Net unamortized discount (10,683 ) Total $ 5,289,317 _______________ (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.

Noncontrolling Interests (Table

Noncontrolling Interests (Tables)	12 Months Ended
	Dec. 31, 2015
Entity Information [Line Items]
Schedule of Redeemable Interest in Property Partnerships [Table Text Block]	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 years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ 97,558 Net loss (1,839 ) Distributions (4,585 ) Adjustment to reflect redeemable interest at redemption value 8,475 Balance at December 31, 2013 99,609 Net loss (603 ) Distributions (6,000 ) Adjustment to reflect redeemable interest at redemption value 11,686 Balance at December 31, 2014 104,692 Net loss (7 ) Distributions (2,900 ) Adjustment to reflect redeemable interest at redemption value 5,128 Acquisition of interest (106,913 ) Balance at December 31, 2015 $ —
Schedule Of Noncontrolling Interest Property Partnerships [Table Text Block]	The following table reflects the activity of the noncontrolling interests—property partnerships for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ (1,964 ) Fair value of capital recorded upon consolidation 480,861 Capital contributions 257,564 Net loss (5,290 ) Distributions (5,039 ) Balance at December 31, 2013 726,132 Capital contributions 887,975 Net income 19,478 Distributions (31,118 ) Balance at December 31, 2014 1,602,467 Capital contributions 3,758 Dissolution (4,082 ) Net income 144,734 Accumulated other comprehensive loss (2,428 ) Distributions (170,049 ) Balance at December 31, 2015 $ 1,574,400
Boston Properties, Inc. [Member]
Entity Information [Line Items]
Schedule Of Redeemable Preferred Units of the Operating Partnership	The following table reflects the activity of the noncontrolling interests—redeemable preferred units of Boston Properties, Inc. for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ 110,876 Net income 6,046 Distributions (6,046 ) Redemption of redeemable preferred units (Series Four Preferred Units) (43,070 ) Conversion of redeemable preferred units (Series Two Preferred Units) to common units (16,494 ) Balance at December 31, 2013 51,312 Net income 1,023 Distributions (1,023 ) Redemption of redeemable preferred units (Series Four Preferred Units) (17,373 ) Conversion of redeemable preferred units (Series Two Preferred Units) to common units (33,306 ) Balance at December 31, 2014 633 Net income 6 Distributions (6 ) Redemption of redeemable preferred units (Series Four Preferred Units) (633 ) Balance at December 31, 2015 $ —
Boston Properties Limited Partnership [Member]
Entity Information [Line Items]
Schedule Of Redeemable Preferred Units of the Operating Partnership	The following table reflects the activity of the noncontrolling interests—redeemable preferred units of Boston Properties Limited Partnership for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ 199,378 Net income 6,046 Distributions (6,046 ) Redemption of redeemable preferred units (Series Four Preferred Units) (43,070 ) Reallocation of partnership interest (1) (50,562 ) Balance at December 31, 2013 105,746 Net income 1,023 Distributions (1,023 ) Redemption of redeemable preferred units (Series Four Preferred Units) (17,373 ) Reallocation of partnership interest (1) (87,740 ) Balance at December 31, 2014 633 Net income 6 Distributions (6 ) Redemption of redeemable preferred units (Series Four Preferred Units) (633 ) Balance at December 31, 2015 $ —
Schedule Of Noncontrolling Interest Common Units [Table Text Block]	The following table reflects the activity of noncontrolling interests—redeemable common units of Boston Properties Limited Partnership for the years ended December 31, 2015 , 2014 and 2013 (in thousands): Balance at December 31, 2012 $ 1,836,522 Contributions 26,398 Net income 84,236 Distributions (83,448 ) Conversion of redeemable partnership units (30,291 ) Unearned compensation 1,472 Other comprehensive income 252 Adjustment to reflect redeemable partnership units at redemption value (124,923 ) Balance at December 31, 2013 1,710,218 Contributions 23,990 Net income 50,862 Distributions (126,948 ) Conversion of redeemable partnership units (2,700 ) Unearned compensation (2,813 ) Other comprehensive income 256 Adjustment to reflect redeemable partnership units at redemption value 657,181 Balance at December 31, 2014 2,310,046 Contributions 39,030 Net income 66,951 Distributions (69,447 ) Conversion of redeemable partnership units (14,343 ) Unearned compensation (4,579 ) Other comprehensive loss (554 ) Adjustment to reflect redeemable partnership units at redemption value (40,415 ) Balance at December 31, 2015 $ 2,286,689

Stockholders' Equity _ Partne39

Stockholders' Equity / Partners' Capital Stockholders Equity / Partners Capital (Tables)	12 Months Ended
	Dec. 31, 2015
Class of Stock [Line Items]
Dividends Declared [Table Text Block]	The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per unit for the periods presented: Record Date Payment Date Dividend (Per Share) Distribution (Per Unit) December 31, 2015 January 28, 2016 $1.90 (1) $1.90 (1) September 30, 2015 October 30, 2015 0.65 0.65 June 30, 2015 July 31, 2015 0.65 0.65 March 31, 2015 April 30, 2015 0.65 0.65 December 31, 2014 January 28, 2015 5.15 (2) 5.15 (2) _______________ (1) Includes a special dividend/distribution of $1.25 per share/common unit. (2) Includes a special dividend/distribution of $4.50 per share/common unit.
Schedule Of Changes In Partners Capital Unit [Table Text Block] [Table Text Block]	The following table presents the changes in the issued and outstanding partners’ capital units since January 1, 2013: General Partner Units Limited Partner Units Total Partners’ Outstanding at December 31, 2012 1,689,580 149,911,629 151,601,209 Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan 50 6,392 6,442 Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net 207 26,686 26,893 Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units 7,158 922,283 929,441 Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs 3,227 415,889 419,116 Outstanding at December 31, 2013 1,700,222 151,282,879 152,983,101 Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan 555 6,409 6,964 Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net 3,476 40,158 43,634 Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units 6,391 73,855 80,246 Outstanding at December 31, 2014 1,710,644 151,403,301 153,113,945 Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan 59 6,140 6,199 Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net 340 35,246 35,586 Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units 4,049 420,187 424,236 Outstanding at December 31, 2015 1,715,092 151,864,874 153,579,966
Schedule of changes in Series B Preferred Units [Table Text Block] [Table Text Block]	The following table reflects the activity of the Series B Preferred Units for the years ended December 31, 2015 , 2014 and 2013 (in thousands), which activity is included within Boston Properties Limited Partnership’s Consolidated Statements of Partners’ Capital: Balance at December 31, 2012 $ — Issuance of Series B Preferred Units 193,623 Net income 8,057 Distributions (8,057 ) Balance at December 31, 2013 193,623 Net income 10,500 Distributions (10,500 ) Balance at December 31, 2014 193,623 Net income 10,500 Distributions (10,500 ) Balance at December 31, 2015 $ 193,623
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Dividends Declared [Table Text Block]	The following table presents Boston Properties Inc.’s dividends per share on its outstanding Series B Preferred Stock: Record Date Payment Date Dividend (Per Share) February 5, 2016 February 16, 2016 $32.8125 November 5, 2015 November 16, 2015 32.8125 August 5, 2015 August 17, 2015 32.8125 May 5, 2015 May 15, 2015 32.8125 February 5, 2015 February 17, 2015 32.8125

Future Minimum Rents (Tables)

Future Minimum Rents (Tables)	12 Months Ended
	Dec. 31, 2015
Future Minimum Rents [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	The future contractual minimum lease payments to be received (excluding operating expense reimbursements) by the Company as of December 31, 2015 , under non-cancelable operating leases which expire on various dates through 2046 , are as follows: Years Ending December 31, (in thousands) 2016 $ 1,854,538 2017 1,815,632 2018 1,733,703 2019 1,666,019 2020 1,500,843 Thereafter 8,667,163

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Schedule Of Segment Information By Geographic Area And Property Type	Information by geographic area and property type (dollars in thousands): For the year ended December 31, 2015 : Boston New York San Francisco Washington, DC Total Rental Revenue: Class A Office $ 692,419 $ 1,000,030 $ 280,005 $ 372,721 $ 2,345,175 Office/Technical 23,827 — 22,429 11,907 58,163 Residential 4,801 — — 14,082 18,883 Hotel 46,046 — — — 46,046 Total 767,093 1,000,030 302,434 398,710 2,468,267 % of Grand Totals 31.08 % 40.52 % 12.25 % 16.15 % 100.00 % Rental Expenses: Class A Office 280,307 346,897 94,268 127,291 848,763 Office/Technical 7,034 — 3,938 4,290 15,262 Residential 2,006 — — 6,221 8,227 Hotel 32,084 — — — 32,084 Total 321,431 346,897 98,206 137,802 904,336 % of Grand Totals 35.54 % 38.36 % 10.86 % 15.24 % 100.00 % Net operating income $ 445,662 $ 653,133 $ 204,228 $ 260,908 $ 1,563,931 % of Grand Totals 28.50 % 41.76 % 13.06 % 16.68 % 100.00 % For the year ended December 31, 2014 : Boston New York San Francisco Washington, DC Total Rental Revenue: Class A Office $ 692,116 $ 928,692 $ 237,381 $ 381,930 $ 2,240,119 Office/Technical 23,801 — 23,840 14,344 61,985 Residential 4,528 — — 21,665 26,193 Hotel 43,385 — — — 43,385 Total 763,830 928,692 261,221 417,939 2,371,682 % of Grand Totals 32.21 % 39.16 % 11.01 % 17.62 % 100.00 % Rental Expenses: Class A Office 270,947 315,330 85,178 131,447 802,902 Office/Technical 7,173 — 4,955 4,338 16,466 Residential 1,957 — — 13,965 15,922 Hotel 29,236 — — — 29,236 Total 309,313 315,330 90,133 149,750 864,526 % of Grand Totals 35.78 % 36.47 % 10.43 % 17.32 % 100.00 % Net operating income $ 454,517 $ 613,362 $ 171,088 $ 268,189 $ 1,507,156 % of Grand Totals 30.16 % 40.70 % 11.35 % 17.79 % 100.00 % For the year ended December 31, 2013 : Boston New York San Francisco Washington, DC Total Rental Revenue: Class A Office $ 665,991 $ 725,566 $ 214,755 $ 381,359 $ 1,987,671 Office/Technical 22,617 — 17,259 15,649 55,525 Residential 4,395 — — 17,923 22,318 Hotel 40,330 — — — 40,330 Total 733,333 725,566 232,014 414,931 2,105,844 % of Grand Totals 34.82 % 34.46 % 11.02 % 19.70 % 100.00 % Rental Expenses: Class A Office 259,997 251,640 77,905 126,507 716,049 Office/Technical 6,879 — 3,708 4,190 14,777 Residential 1,823 — — 10,307 12,130 Hotel 28,447 — — — 28,447 Total 297,146 251,640 81,613 141,004 771,403 % of Grand Totals 38.52 % 32.62 % 10.58 % 18.28 % 100.00 % Net operating income $ 436,187 $ 473,926 $ 150,401 $ 273,927 $ 1,334,441 % of Grand Totals 32.69 % 35.51 % 11.27 % 20.53 % 100.00 %
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. common shareholders (in thousands): Year ended December 31, 2015 2014 2013 Net Operating Income $ 1,563,931 $ 1,507,156 $ 1,334,441 Add: Development and management services income 22,554 25,316 29,695 Income from unconsolidated joint ventures 22,770 12,769 75,074 Gains on consolidation of joint ventures — — 385,991 Interest and other income 6,777 8,765 8,310 Gains (losses) from investments in securities (653 ) 1,038 2,911 Gains (losses) from early extinguishments of debt (22,040 ) (10,633 ) 122 Income from discontinued operations — — 8,022 Gains on sales of real estate from discontinued operations — — 112,829 Gain on forgiveness of debt from discontinued operations — — 20,182 Gains on sales of real estate 375,895 168,039 — Less: General and administrative expense 96,319 98,937 115,329 Transaction costs 1,259 3,140 1,744 Depreciation and amortization expense 639,542 628,573 560,637 Interest expense 432,196 455,743 446,880 Impairment loss — — 8,306 Impairment loss from discontinued operations — — 3,241 Noncontrolling interest in property partnerships 149,855 30,561 1,347 Noncontrolling interest—redeemable preferred units of the Operating Partnership 6 1,023 6,046 Noncontrolling interest—common units of the Operating Partnership 66,951 50,862 70,085 Noncontrolling interest in discontinued operations—common units of the Operating Partnership — — 14,151 Preferred dividends 10,500 10,500 8,057 Net income attributable to Boston Properties, Inc. common shareholders $ 572,606 $ 433,111 $ 741,754 Boston Properties Limited Partnership The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership common unitholders (in thousands): Year ended December 31, 2015 2014 2013 Net Operating Income $ 1,563,931 $ 1,507,156 $ 1,334,441 Add: Development and management services income 22,554 25,316 29,695 Income from unconsolidated joint ventures 22,770 12,769 75,074 Gains on consolidation of joint ventures — — 385,991 Interest and other income 6,777 8,765 8,310 Gains (losses) from investments in securities (653 ) 1,038 2,911 Gains (losses) from early extinguishments of debt (22,040 ) (10,633 ) 122 Income from discontinued operations — — 8,022 Gains on sales of real estate from discontinued operations — — 115,459 Gain on forgiveness of debt from discontinued operations — — 20,736 Gains on sales of real estate 377,093 174,686 — Less: General and administrative expense 96,319 98,937 115,329 Transaction costs 1,259 3,140 1,744 Depreciation and amortization expense 631,549 620,064 552,589 Interest expense 432,196 455,743 446,880 Impairment loss — — 4,401 Impairment loss from discontinued operations — — 2,852 Noncontrolling interest in property partnerships 149,855 30,561 1,347 Noncontrolling interest—redeemable preferred units 6 1,023 6,046 Preferred distributions 10,500 10,500 8,057 Net income attributable to Boston Properties Limited Partnership common unitholders $ 648,748 $ 499,129 $ 841,516

Earnings Per Share _ Common U42

Earnings Per Share / Common Unit (Tables)	12 Months Ended
	Dec. 31, 2015
Entity Information [Line Items]
Computation Of Basic And Diluted Earnings Per Share / Unit	For the Year Ended December 31, 2015 Income (Numerator) Shares (Denominator) Per Share Amount (in thousands, except for per share amounts) Basic Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 572,606 153,471 $ 3.73 Effect of Dilutive Securities: Stock Based Compensation — 373 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 572,606 153,844 $ 3.72 For the Year Ended December 31, 2014 Income (Numerator) Shares (Denominator) Per Share Amount (in thousands, except for per share amounts) Basic Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 433,111 153,089 $ 2.83 Effect of Dilutive Securities: Stock Based Compensation — 219 — Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 433,111 153,308 $ 2.83 For the Year Ended December 31, 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. $ 618,113 152,201 $ 4.06 Discontinued operations attributable to Boston Properties, Inc. 123,641 — 0.81 Allocation of undistributed earnings to participating securities (160 ) — — Net income attributable to Boston Properties, Inc. common shareholders $ 741,594 152,201 $ 4.87 Effect of Dilutive Securities: Stock Based Compensation and Exchangeable Senior Notes — 320 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 741,594 152,521 $ 4.86
Boston Properties Limited Partnership [Member]
Entity Information [Line Items]
Computation Of Basic And Diluted Earnings Per Share / Unit	Other potentially dilutive common units and the related impact on earnings are considered when calculating diluted earnings per common unit. Included in the number of units (the denominator) below are approximately 17,668,000 , 17,364,000 and 16,925,000 redeemable common units for the years ended December 31, 2015 , 2014 and 2013 , respectively. For the Year Ended December 31, 2015 Income (Numerator) Units (Denominator) Per Unit Amount (in thousands, except for per unit amounts) Basic Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 648,748 171,139 $ 3.79 Effect of Dilutive Securities: Stock Based Compensation — 373 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 648,748 171,512 $ 3.78 For the Year Ended December 31, 2014 Income (Numerator) Units (Denominator) Per Unit Amount (in thousands, except for per unit amounts) Basic Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 499,129 170,453 $ 2.93 Effect of Dilutive Securities: Stock Based Compensation — 219 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 499,129 170,672 $ 2.92 For the Year Ended December 31, 2013 Income (Numerator) Units (Denominator) Per Unit Amount (in thousands, except for per unit amounts) Basic Earnings: Income from continuing operations attributable to Boston Properties Limited Partnership $ 700,151 169,126 $ 4.14 Discontinued operations attributable to Boston Properties Limited Partnership 141,365 — 0.84 Allocation of undistributed earnings to participating securities (178 ) — (0.01 ) Net income attributable to Boston Properties Limited Partnership common unitholders $ 841,338 169,126 $ 4.97 Effect of Dilutive Securities: Stock Based Compensation and Exchangeable Senior Notes — 320 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 841,338 169,446 $ 4.97

Stock Option and Incentive Pl43

Stock Option and Incentive Plan Stock Option and Incentive Plan and Stock Purchase Plan (Tables)	12 Months Ended
	Dec. 31, 2015
Stock Option and Incentive Plan and Stock Purchase Plan [Abstract]
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	A summary of the status of Boston Properties, Inc.’s stock options as of December 31, 2015 , 2014 and 2013 and changes during the years then ended are presented below: Shares Weighted-Average Exercise Price Outstanding at December 31, 2012 294,527 $ 101.06 Granted 252,220 $ 104.50 Special dividend adjustment 12,076 $ 100.44 Outstanding at December 31, 2013 558,823 $ 100.43 Exercised (21,459 ) $ 97.04 Canceled (2,444 ) $ 103.57 Special dividend adjustment 18,392 $ 97.22 Outstanding at December 31, 2014 553,312 $ 97.21 Exercised (11,447 ) $ 92.50 Special dividend adjustment 5,264 $ 96.38 Outstanding at December 31, 2015 547,129 $ 96.38
Schedule of Stock Options Outstanding [Table Text Block]	The following table summarizes information about Boston Properties, Inc.’s stock options outstanding at December 31, 2015 : Options Outstanding Options Exercisable Number Outstanding at 12/31/15 Weighted-Average Remaining Contractual Life Exercise Price Number Exercisable at 12/31/15 Exercise Price 118,502 5.1 years $ 86.86 118,502 $ 86.86 54,282 7.3 years $ 95.69 27,141 $ 95.69 206,728 7.1 years $ 98.46 168,332 $ 98.46 167,617 6.1 years $ 100.77 151,396 $ 100.77

Selected Interim Financial In44

Selected Interim Financial Information (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	2015 Quarter Ended March 31, June 30, September 30, December 31, (in thousands, except for per share amounts) Total revenue $ 618,476 $ 618,221 $ 629,884 $ 624,240 Income before gains on sales of real estate $ 114,086 $ 100,739 $ 123,792 $ 85,406 Net income attributable to Boston Properties, Inc. common shareholders $ 171,182 $ 79,460 $ 184,082 $ 137,851 Income attributable to Boston Properties, Inc. per share—basic $ 1.12 $ 0.52 $ 1.20 $ 0.90 Income attributable to Boston Properties, Inc. per share—diluted $ 1.11 $ 0.52 $ 1.20 $ 0.90 2014 Quarter Ended March 31, June 30, September 30, December 31, (in thousands, except for per share amounts) Total revenue $ 574,694 $ 589,794 $ 618,803 $ 613,707 Income before gains on sales of real estate $ 67,756 $ 95,901 $ 109,038 $ 85,323 Net income attributable to Boston Properties, Inc. common shareholders $ 54,034 $ 76,527 $ 127,724 $ 174,510 Income attributable to Boston Properties, Inc. per share—basic $ 0.35 $ 0.50 $ 0.83 $ 1.14 Income attributable to Boston Properties, Inc. per share—diluted $ 0.35 $ 0.50 $ 0.83 $ 1.14 Boston Properties Limited Partnership The tables below reflect Boston Properties Limited Partnership’s selected quarterly information for the years ended December 31, 2015 and 2014 . 2015 Quarter Ended March 31, June 30, September 30, December 31, (in thousands, except for per unit amounts) Total revenue $ 618,476 $ 618,221 $ 629,884 $ 624,240 Income before gains on sales of real estate $ 116,085 $ 102,737 $ 125,790 $ 87,404 Net income attributable to Boston Properties Limited Partnership common unitholders $ 193,369 $ 90,852 $ 207,626 $ 156,901 Income attributable to Boston Properties Limited Partnership per unit—basic $ 1.13 $ 0.53 $ 1.21 $ 0.92 Income attributable to Boston Properties Limited Partnership per unit—diluted $ 1.12 $ 0.53 $ 1.21 $ 0.92 2014 Quarter Ended March 31, June 30, September 30, December 31, (in thousands, except for per unit amounts) Total revenue $ 574,694 $ 589,794 $ 618,803 $ 613,707 Income before gains on sales of real estate $ 69,781 $ 97,927 $ 111,066 $ 87,753 Net income attributable to Boston Properties Limited Partnership common unitholders $ 62,219 $ 87,436 $ 144,715 $ 204,759 Income attributable to Boston Properties Limited Partnership per unit—basic $ 0.37 $ 0.51 $ 0.85 $ 1.20 Income attributable to Boston Properties Limited Partnership per unit—diluted $ 0.37 $ 0.51 $ 0.85 $ 1.20

Real Estate and Accumulated D45

Real Estate and Accumulated Depreciation Real Estate and Accumulated Depreciation (Tables)	12 Months Ended
	Dec. 31, 2015
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, By Property [Table Text Block]	Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Property Name Type Location Encumbrances Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Land Building 767 Fifth Avenue (the General Motors Building) Office New York, NY $ 1,377,986 $ 1,796,252 $ 1,532,654 $ 45,800 $ 1,796,252 $ 1,578,454 $ — $ — $ 3,374,706 $ 128,488 1968 (1) Embarcadero Center Office San Francisco, CA 348,886 179,697 847,410 332,276 195,987 1,163,396 — — 1,359,383 542,103 1970/1989 (1) Prudential Center Office Boston, MA — 92,077 734,594 526,740 107,426 1,082,583 1,714 161,688 1,353,411 446,792 1965/1993/2002 (1) 399 Park Avenue Office New York, NY — 339,200 700,358 110,972 354,107 796,423 — — 1,150,530 265,266 1961 (1) 200 Clarendon Street and Garage (formerly the John Hancock Tower and Garage) Office Boston, MA — 219,543 667,884 112,229 219,616 776,755 3,285 — 999,656 128,815 1976 (1) 601 Lexington Avenue Office New York, NY 699,061 241,600 494,782 231,812 289,639 677,238 1,317 — 968,194 250,128 1977/1997 (1) 250 West 55th Street Office New York, NY — 285,263 603,167 16,488 285,263 619,655 — — 904,918 28,349 2014 (1) Times Square Tower Office New York, NY — 165,413 380,438 84,722 169,193 461,380 — — 630,573 164,767 2004 (1) Carnegie Center Office Princeton, NJ — 105,107 377,259 128,069 103,064 464,086 2,475 40,810 610,435 198,387 1983-1999 (1) 100 Federal Street Office Boston, MA — 131,067 435,954 15,555 131,067 450,933 576 — 582,576 60,125 1971-1975 (1) Atlantic Wharf Office Boston, MA — 63,988 454,537 16,376 63,988 470,913 — — 534,901 70,552 2011 (1) 510 Madison Avenue Office New York, NY — 103,000 253,665 19,575 103,000 273,240 — — 376,240 34,640 2012 (1) Fountain Square Office Reston, VA 213,499 56,853 306,298 12,459 56,853 318,757 — — 375,610 39,508 1986-1990 (1) 599 Lexington Avenue Office New York, NY 750,000 81,040 100,507 149,551 87,852 243,246 — — 331,098 160,354 1986 (1) 680 Folsom Street Office San Francisco, CA — 72,545 219,766 7,348 72,545 227,114 — — 299,659 13,091 2014 (1) South of Market and Democracy Tower Office Reston, VA — 13,603 237,479 11,977 13,687 249,372 — — 263,059 70,437 2008-2009 (1) Bay Colony Corporate Center Office Waltham, MA — 18,789 148,451 65,997 18,789 214,448 — — 233,237 40,812 1985-1989 (1) Gateway Center Office San Francisco, CA — 28,255 139,245 54,027 30,627 190,900 — — 221,527 94,083 1984/1986/2002 (1) 535 Mission Street Office San Francisco, CA — 40,933 148,378 — 40,933 148,378 — — 189,311 3,221 2015 (1) 2200 Pennsylvania Avenue Office Washington, DC — — 183,541 5,230 — 188,771 — — 188,771 33,039 2011 (1) Mountain View Research Park Office Mountain View, CA — 95,066 68,373 5,581 95,066 73,954 — — 169,020 9,581 1977-1981/2007-2013 (1) Reservoir Place Office Waltham, MA — 18,605 92,619 46,547 20,118 128,975 — 8,678 157,771 57,706 1955/1987 (1) 1333 New Hampshire Avenue Office Washington, DC — 34,032 85,660 10,841 35,382 95,151 — — 130,533 35,457 1996 (1) Kingstowne Towne Center Office Alexandria, VA — 18,021 109,038 1,276 18,062 110,273 — — 128,335 33,374 2003-2006 (1) 1330 Connecticut Avenue Office Washington, DC — 25,982 82,311 19,098 27,135 100,256 — — 127,391 45,063 1984 (1) Capital Gallery Office Washington, DC — 4,725 29,565 88,569 8,662 114,197 — — 122,859 57,489 1981/2006 (1) Weston Corporate Center Office Weston, MA — 25,753 92,312 (123 ) 25,854 92,088 — — 117,942 17,023 2010 (1) One Freedom Square Office Reston, VA — 9,929 84,504 19,613 11,293 102,753 — — 114,046 41,106 2000 (1) Two Freedom Square Office Reston, VA — 13,930 77,739 21,374 15,420 97,623 — — 113,043 41,164 2001 (1) Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Property Name Type Location Encumbrances Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Land Building One and Two Reston Overlook Office Reston, VA — 16,456 66,192 22,385 16,179 88,854 — — 105,033 37,165 1999 (1) Discovery Square Office Reston, VA — 11,198 71,782 21,234 12,533 91,681 — — 104,214 35,835 2001 (1) 415 Main Street Office Cambridge, MA — 3,457 97,136 2,986 4,125 99,454 — — 103,579 59,405 2006 (1) 355 Main Street Office Cambridge, MA — 18,863 53,346 28,822 21,173 79,858 — — 101,031 23,372 1981/1996/2013 (1) 140 Kendrick Street Office Needham, MA — 18,095 66,905 15,075 19,092 80,983 — — 100,075 23,191 2000 (1) 90 Broadway Office Cambridge, MA — 19,104 52,078 17,386 20,785 67,783 — — 88,568 14,394 1983/1998/2013 (1) 230 CityPoint Office Waltham, MA — 13,189 49,823 18,800 13,593 68,219 — — 81,812 20,265 1992 (1) Waltham Weston Corporate Center Office Waltham, MA — 10,385 60,694 8,907 11,097 68,889 — — 79,986 24,699 2003 (1) 77 CityPoint Office Waltham, MA — 13,847 60,383 5,605 13,873 65,962 — — 79,835 18,930 2008 (1) North First Business Park Office San Jose, CA — 58,402 13,069 4,028 23,377 16,214 35,908 — 75,499 14,139 1981 (1) 300 Binney Street Office Cambridge, MA — 18,080 51,262 140 18,080 51,402 — — 69,482 4,375 2013 (1) 2440 West El Camino Real Office Mountain View, CA — 16,741 51,285 1,422 16,741 52,707 — — 69,448 8,185 1987/2003 (1) Reston Corporate Center Office Reston, VA — 9,135 50,857 6,464 10,148 56,308 — — 66,456 23,962 1984 (1) Wisconsin Place Office Chevy Chase, MD — — 53,349 12,787 — 66,136 — — 66,136 18,272 2009 (1) New Dominion Technology Park, Bldg. Two Office Herndon, VA — 5,584 51,868 3,911 6,510 54,853 — — 61,363 20,110 2004 (1) Sumner Square Office Washington, DC — 624 28,745 26,196 1,478 54,087 — — 55,565 26,923 1985 (1) 200 West Street Office Waltham, MA — 16,148 24,983 10,102 16,813 34,420 — — 51,233 18,034 1999 (1) New Dominion Technology Park, Bldg. One Office Herndon, VA 38,494 3,880 43,227 3,883 4,583 46,407 — — 50,990 22,760 2001 (1) 191 Spring Street Office Lexington, MA — 2,850 27,166 18,610 3,151 45,475 — — 48,626 32,535 1971/1995 (1) University Place Office Cambridge, MA 10,788 — 37,091 9,483 390 46,184 — — 46,574 23,635 1985 (1) 2600 Tower Oaks Boulevard Office Rockville, MD — 4,243 31,125 8,656 4,785 39,239 — — 44,024 18,386 2001 (1) 255 Main Street Office Cambridge, MA — 134 25,110 18,559 548 43,255 — — 43,803 27,153 1987 (1) Quorum Office Park Office Chelmsford, MA — 3,750 32,454 5,814 5,187 36,831 — — 42,018 14,671 2001 (1) 500 E Street Office Washington, DC — 109 22,420 13,144 2,379 33,294 — — 35,673 22,616 1987 (1) 150 Broadway Office Cambridge, MA — 850 25,042 8,623 1,323 33,192 — — 34,515 14,073 1999 (1) 325 Main Street Office Cambridge, MA — 174 12,200 12,368 965 23,777 — — 24,742 11,339 1987/2013 (1) 105 Broadway Office Cambridge, MA — 1,299 12,943 7,177 2,395 19,024 — — 21,419 12,556 1990 (1) 40 Shattuck Road Office Andover, MA — 709 14,740 3,184 893 17,740 — — 18,633 6,846 2001 (1) Lexington Office Park Office Lexington, MA — 998 1,426 16,099 1,264 17,259 — — 18,523 11,730 1982 (1) 201 Spring Street Office Lexington, MA — 2,849 15,303 (154 ) 3,124 14,874 — — 17,998 6,987 1997 (1) The Point (formerly 99 Third Avenue Retail) Office Waltham, MA — 6,395 10,040 — 6,395 10,040 — — 16,435 76 2015 (1) 91 Hartwell Avenue Office Lexington, MA — 784 6,464 8,192 941 14,499 — — 15,440 8,525 1985 (1) 92-100 Hayden Avenue Office Lexington, MA — 594 6,748 8,034 802 14,574 — — 15,376 11,412 1985 (1) 690 Folsom Street Office San Francisco, CA — 3,219 11,038 — 3,219 11,038 — — 14,257 334 2015 (1) 195 West Street Office Waltham, MA — 1,611 6,652 4,340 1,858 10,745 — — 12,603 7,071 1990 (1) 181 Spring Street Office Lexington, MA — 1,066 9,520 1,993 1,160 11,419 — — 12,579 4,580 1999 (1) Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Property Name Type Location Encumbrances Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Land Building 33 Hayden Avenue Office Lexington, MA — 266 3,234 8,787 425 11,862 — — 12,287 6,586 1979 (1) 145 Broadway Office Cambridge, MA — 121 5,535 5,305 324 10,637 — — 10,961 7,864 1984 (1) 7501 Boston Boulevard, Building Seven Office Springfield, VA — 665 9,273 520 791 9,667 — — 10,458 4,355 1997 (1) 7435 Boston Boulevard, Building One Office Springfield, VA — 392 3,822 4,218 659 7,773 — — 8,432 6,052 1982 (1) 250 Binney Street Office Cambridge, MA — 110 4,483 3,593 273 7,913 — — 8,186 4,303 1983 (1) 7450 Boston Boulevard, Building Three Office Springfield, VA — 1,165 4,681 1,880 1,430 6,296 — — 7,726 3,226 1987 (1) 8000 Grainger Court, Building Five Office Springfield, VA — 366 4,282 2,684 601 6,731 — — 7,332 5,336 1984 (1) 453 Ravendale Drive Office Mountain View, CA — 5,477 1,090 235 5,479 1,323 — — 6,802 265 1977 (1) 7500 Boston Boulevard, Building Six Office Springfield, VA — 138 3,749 2,617 406 6,098 — — 6,504 4,499 1985 (1) 7300 Boston Boulevard, Building Thirteen Office Springfield, VA — 608 4,773 709 661 5,429 — — 6,090 4,626 2002 (1) 7601 Boston Boulevard, Building Eight Office Springfield, VA — 200 878 4,924 551 5,451 — — 6,002 3,849 1986 (1) 8000 Corporate Court, Building Eleven Office Springfield, VA — 136 3,071 1,615 775 4,047 — — 4,822 2,639 1989 (1) 7375 Boston Boulevard, Building Ten Office Springfield, VA — 23 2,685 1,003 93 3,618 — — 3,711 2,464 1988 (1) 7374 Boston Boulevard, Building Four Office Springfield, VA — 241 1,605 1,735 398 3,183 — — 3,581 2,345 1984 (1) 7451 Boston Boulevard, Building Two Office Springfield, VA — 249 1,542 1,661 613 2,839 — — 3,452 2,233 1982 (1) 32 Hartwell Avenue Office Lexington, MA — 168 1,943 1,193 314 2,990 — — 3,304 1,786 1968-1979/1987 (1) 164 Lexington Road Office Billerica, MA — 592 1,370 319 643 1,638 — — 2,281 786 1982 (1) 17 Hartwell Avenue Office Lexington, MA — 26 150 614 65 725 — — 790 323 1968 (1) The Avant at Reston Town Center Residential Reston, VA — 20,350 91,995 813 20,350 92,808 — — 113,158 4,833 2014 (1) The Lofts at Atlantic Wharf Residential Boston, MA — 3,529 54,891 1,579 3,529 56,470 — — 59,999 6,596 2011 (1) Boston Marriott Cambridge Hotel Cambridge, MA — 478 37,918 35,665 1,201 72,860 — — 74,061 48,162 1986 (1) Kendall Center Green Garage (formerly Cambridge Center East Garage) Garage Cambridge, MA — — 35,035 4,254 103 39,186 — — 39,289 8,610 1984 (1) Kendall Center Yellow Garage (formerly Cambridge Center West Garage) Garage Cambridge, MA — 1,256 15,697 1,571 1,434 17,090 — — 18,524 4,269 2006 (1) Kendall Center Blue Garage (formerly Cambridge Center North Garage) Garage Cambridge, MA — 1,163 11,633 2,770 1,579 13,987 — — 15,566 8,941 1990 (1) Salesforce Tower Development San Francisco, CA — — — 429,767 — — — 429,767 429,767 — N/A N/A 601 Massachusetts Avenue Development Washington, DC — — — 253,176 95,322 140,791 — 17,063 253,176 1,531 N/A N/A 10 CityPoint Development Waltham, MA — — — 70,389 163 — — 70,226 70,389 — N/A N/A Reston Signature Site Development Reston, VA — — — 38,886 — — 12,678 26,208 38,886 — N/A N/A Cambridge Residential / 88 Ames Development Cambridge, MA — — — 9,495 — — — 9,495 9,495 — N/A N/A Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Property Name Type Location Encumbrances Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Land Building Springfield Metro Center Land Springfield, VA — — — 34,870 — — 34,870 — 34,870 — N/A N/A Tower Oaks Master Plan Land Rockville, MD — — — 29,022 — — 29,022 — 29,022 — N/A N/A Plaza at Almaden Land San Jose, CA — — — 29,010 — — 29,010 — 29,010 — N/A N/A 6601 & 6605 Springfield Center Drive Land Springfield, VA — — — 13,866 — — 13,866 — 13,866 — N/A N/A 214 Third Avenue Land Waltham, MA — — — 13,415 — 132 13,283 — 13,415 — N/A N/A 103 Fourth Avenue Land Waltham, MA — — — 11,927 — — 11,927 — 11,927 — N/A N/A Reston Gateway Land Reston, VA — — — 10,294 — — 10,294 — 10,294 — N/A N/A 20 CityPoint Land Waltham, MA — — — 10,258 — — 10,258 — 10,258 — N/A N/A Reston Eastgate Land Reston, VA — — — 9,215 — — 9,215 — 9,215 — N/A N/A Washingtonian North Land Gaithersburg, MD — — — 8,836 — — 8,836 — 8,836 — N/A N/A Crane Meadow Land Marlborough, MA — — — 8,727 — — 8,727 — 8,727 — N/A N/A Broad Run Business Park Land Loudoun County, VA — — — 6,399 — — 6,399 — 6,399 — N/A N/A North First Master Plan Land San Jose, CA — — — 2,999 — — 2,999 — 2,999 — N/A N/A Fourth and Harrison (formerly 425 Fourth Street) Land San Francisco, CA — — — 2,920 — — 2,920 — 2,920 — N/A N/A Kendall Center Master Plan (formerly Cambridge Master Plan) Land Cambridge, MA — — — 1,403 — — 1,403 — 1,403 — N/A N/A 30 Shattuck Road Land Andover, MA — — — 1,213 — — 1,213 — 1,213 — N/A N/A $ 3,438,714 (2 ) $ 4,602,809 $ 11,248,289 $ 3,600,585 $ 4,806,021 $ 13,629,532 $ 252,195 $ 763,935 $ 19,451,683 $ 3,905,940 Note: Total Real Estate does not include Furniture, Fixtures and Equipment totaling approximately $29,852 . Accumulated Depreciation does not include approximately $19,954 of accumulated depreciation related to Furniture, Fixtures and Equipment. The aggregate cost and accumulated depreciation for tax purposes was approximately $15.0 billion and $3.0 billion , respectively. (1) Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years. (2) Includes the unamortized balance of the historical fair value adjustment totaling approximately $80.2 million .
Activity of Real Estate and Accumulated Depreciation [Table Text Block]	A summary of activity for real estate and accumulated depreciation is as follows: 2015 2014 2013 Real Estate: Balance at the beginning of the year $ 19,208,417 $ 18,953,601 $ 14,869,887 Additions to/improvements of real estate 700,792 594,296 4,410,622 Assets sold/written-off (457,526 ) (339,480 ) (326,908 ) Balance at the end of the year $ 19,451,683 $ 19,208,417 $ 18,953,601 Accumulated Depreciation: Balance at the beginning of the year $ 3,529,978 $ 3,145,701 $ 2,919,479 Depreciation expense 486,450 456,176 419,908 Assets sold/written-off (110,488 ) (71,899 ) (193,686 ) Balance at the end of the year $ 3,905,940 $ 3,529,978 $ 3,145,701 Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.
Boston Properties Limited Partnership [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, By Property [Table Text Block]	Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Property Name Type Location Encumbrances Land Building 767 Fifth Avenue (the General Motors Building) Office New York, NY $ 1,377,986 $ 1,796,252 $ 1,532,654 $ 45,800 $ 1,796,252 $ 1,578,454 $ — $ — $ 3,374,706 $ 128,488 1968 (1) Prudential Center Office Boston, MA — 92,077 734,594 466,370 92,328 1,037,311 1,714 161,688 1,293,041 435,437 1965/1993/2002 (1) Embarcadero Center Office San Francisco, CA 348,886 179,697 847,410 269,895 180,420 1,116,582 — — 1,297,002 530,307 1970/1989 (1) 399 Park Avenue Office New York, NY — 339,200 700,358 51,364 339,200 751,722 — — 1,090,922 254,028 1961 (1) 200 Clarendon Street and Garage (formerly the John Hancock Tower and Garage) Office Boston, MA — 219,543 667,884 112,229 219,616 776,755 3,285 — 999,656 128,815 1976 (1) 601 Lexington Avenue Office New York, NY 699,061 241,600 494,782 190,393 279,281 646,177 1,317 — 926,775 242,358 1977/1997 (1) 250 West 55th Street Office New York, NY — 285,263 603,167 16,488 285,263 619,655 — — 904,918 28,349 2014 (1) Carnegie Center Office Princeton, NJ — 105,107 377,259 110,751 98,733 451,099 2,475 40,810 593,117 195,128 1983-1999 (1) Times Square Tower Office New York, NY — 165,413 380,438 46,743 159,694 432,900 — — 592,594 157,622 2004 (1) 100 Federal Street Office Boston, MA — 131,067 435,954 15,555 131,067 450,933 576 — 582,576 60,125 1971-1975 (1) Atlantic Wharf Office Boston, MA — 63,988 454,537 16,376 63,988 470,913 — — 534,901 70,552 2011 (1) 510 Madison Avenue Office New York, NY — 103,000 253,665 19,575 103,000 273,240 — — 376,240 34,640 2012 (1) Fountain Square Office Reston, VA 213,499 56,853 306,298 12,459 56,853 318,757 — — 375,610 39,508 1986-1990 (1) 599 Lexington Avenue Office New York, NY 750,000 81,040 100,507 122,309 81,040 222,816 — — 303,856 155,235 1986 (1) 680 Folsom Street Office San Francisco, CA — 72,545 219,766 7,348 72,545 227,114 — — 299,659 13,091 2014 (1) South of Market and Democracy Tower Office Reston, VA — 13,603 237,479 11,641 13,603 249,120 — — 262,723 70,389 2008-2009 (1) Bay Colony Corporate Center Office Waltham, MA — 18,789 148,451 65,997 18,789 214,448 — — 233,237 40,812 1985-1989 (1) Gateway Center Office San Francisco, CA — 28,255 139,245 47,638 29,029 186,109 — — 215,138 92,882 1984/1986/2002 (1) 535 Mission Street Office San Francisco, CA — 40,933 148,378 — 40,933 148,378 — — 189,311 3,221 2015 (1) 2200 Pennsylvania Avenue Office Washington, DC — — 183,541 5,230 — 188,771 — — 188,771 33,039 2011 (1) Mountain View Research Park Office Mountain View, CA — 95,066 68,373 5,581 95,066 73,954 — — 169,020 9,581 1977-1981/2007-2013 (1) Reservoir Place Office Waltham, MA — 18,605 92,619 42,472 19,099 125,919 — 8,678 153,696 56,939 1955/1987 (1) Kingstowne Towne Center Office Alexandria, VA — 18,021 109,038 1,112 18,021 110,150 — — 128,171 33,350 2003-2006 (1) 1333 New Hampshire Avenue Office Washington, DC — 34,032 85,660 5,447 34,032 91,107 — — 125,139 34,441 1996 (1) 1330 Connecticut Avenue Office Washington, DC — 25,982 82,311 14,485 25,982 96,796 — — 122,778 44,193 1984 (1) Weston Corporate Center Office Weston, MA — 25,753 92,312 (123 ) 25,854 92,088 — — 117,942 17,023 2010 (1) Capital Gallery Office Washington, DC — 4,725 29,565 78,438 6,128 106,600 — — 112,728 55,581 1981/2006 (1) One Freedom Square Office Reston, VA — 9,929 84,504 13,976 9,883 98,526 — — 108,409 40,044 2000 (1) Two Freedom Square Office Reston, VA — 13,930 77,739 15,162 13,866 92,965 — — 106,831 39,996 2001 (1) 415 Main Street Office Cambridge, MA — 3,457 97,136 316 3,457 97,452 — — 100,909 58,907 2006 (1) 355 Main Street Office Cambridge, MA — 18,863 53,346 28,524 21,098 79,635 — — 100,733 23,319 1981/1996/2013 (1) One and Two Reston Overlook Office Reston, VA — 16,456 66,192 17,967 15,074 85,541 — — 100,615 36,334 1999 (1) Discovery Square Office Reston, VA — 11,198 71,782 15,689 11,146 87,523 — — 98,669 34,789 2001 (1) 140 Kendrick Street Office Needham, MA — 18,095 66,905 11,085 18,095 77,990 — — 96,085 22,441 2000 (1) Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Property Name Type Location Encumbrances Land Building 90 Broadway Office Cambridge, MA — 19,104 52,078 17,207 20,741 67,648 — — 88,389 14,366 1983/1998/2013 (1) 230 CityPoint Office Waltham, MA — 13,189 49,823 17,183 13,189 67,006 — — 80,195 19,965 1992 (1) 77 CityPoint Office Waltham, MA — 13,847 60,383 5,500 13,847 65,883 — — 79,730 18,914 2008 (1) Waltham Weston Corporate Center Office Waltham, MA — 10,385 60,694 5,920 10,350 66,649 — — 76,999 24,136 2003 (1) North First Business Park Office San Jose, CA — 58,402 13,069 4,005 23,371 16,197 35,908 — 75,476 14,139 1981 (1) 300 Binney Street Office Cambridge, MA — 18,080 51,262 140 18,080 51,402 — — 69,482 4,375 2013 (1) 2440 West El Camino Real Office Mountain View, CA — 16,741 51,285 1,422 16,741 52,707 — — 69,448 8,185 1987/2003 (1) Wisconsin Place Office Chevy Chase, MD — — 53,349 12,787 — 66,136 — — 66,136 18,272 2009 (1) Reston Corporate Center Office Reston, VA — 9,135 50,857 3,853 9,496 54,349 — — 63,845 23,471 1984 (1) New Dominion Technology Park, Bldg. Two Office Herndon, VA — 5,584 51,868 166 5,574 52,044 — — 57,618 19,401 2004 (1) Sumner Square Office Washington, DC — 624 28,745 24,116 958 52,527 — — 53,485 26,534 1985 (1) 200 West Street Office Waltham, MA — 16,148 24,983 7,441 16,148 32,424 — — 48,572 17,532 1999 (1) New Dominion Technology Park, Bldg. One Office Herndon, VA 38,494 3,880 43,227 1,074 3,880 44,301 — — 48,181 22,230 2001 (1) 191 Spring Street Office Lexington, MA — 2,850 27,166 17,411 2,850 44,577 — — 47,427 32,307 1971/1995 (1) University Place Office Cambridge, MA 10,788 — 37,091 8,033 27 45,097 — — 45,124 23,365 1985 (1) 255 Main Street Office Cambridge, MA — 134 25,110 16,903 134 42,013 — — 42,147 26,843 1987 (1) 2600 Tower Oaks Boulevard Office Rockville, MD — 4,243 31,125 6,493 4,244 37,617 — — 41,861 17,977 2001 (1) Quorum Office Park Office Chelmsford, MA — 3,750 32,454 4,115 4,762 35,557 — — 40,319 14,352 2001 (1) 150 Broadway Office Cambridge, MA — 850 25,042 6,618 822 31,688 — — 32,510 13,693 1999 (1) 500 E Street Office Washington, DC — 109 22,420 9,904 1,569 30,864 — — 32,433 22,008 1987 (1) 325 Main Street Office Cambridge, MA — 174 12,200 11,597 772 23,199 — — 23,971 11,192 1987/2013 (1) 105 Broadway Office Cambridge, MA — 1,299 12,943 5,071 1,868 17,445 — — 19,313 12,158 1990 (1) 40 Shattuck Road Office Andover, MA — 709 14,740 2,448 709 17,188 — — 17,897 6,707 2001 (1) Lexington Office Park Office Lexington, MA — 998 1,426 15,335 1,073 16,686 — — 17,759 11,589 1982 (1) 201 Spring Street Office Lexington, MA — 2,849 15,303 (1,253 ) 2,849 14,050 — — 16,899 6,779 1997 (1) The Point (formerly 99 Third Avenue Retail) Office Waltham, MA — 6,395 10,040 — 6,395 10,040 — — 16,435 76 2015 (1) 91 Hartwell Avenue Office Lexington, MA — 784 6,464 7,565 784 14,029 — — 14,813 8,405 1985 (1) 92-100 Hayden Avenue Office Lexington, MA — 594 6,748 7,305 619 14,028 — — 14,647 11,274 1985 (1) 690 Folsom Street Office San Francisco, CA — 3,219 11,038 — 3,219 11,038 — — 14,257 334 2015 (1) 181 Spring Street Office Lexington, MA — 1,066 9,520 1,616 1,066 11,136 — — 12,202 4,509 1999 (1) 33 Hayden Avenue Office Lexington, MA — 266 3,234 8,150 266 11,384 — — 11,650 6,466 1979 (1) 195 West Street Office Waltham, MA — 1,611 6,652 3,351 1,611 10,003 — — 11,614 6,882 1990 (1) 145 Broadway Office Cambridge, MA — 121 5,535 4,492 121 10,027 — — 10,148 7,713 1984 (1) 7501 Boston Boulevard, Building Seven Office Springfield, VA — 665 9,273 15 665 9,288 — — 9,953 4,259 1997 (1) 7435 Boston Boulevard, Building One Office Springfield, VA — 392 3,822 3,525 486 7,253 — — 7,739 5,922 1982 (1) Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Property Name Type Location Encumbrances Land Building 250 Binney Street Office Cambridge, MA — 110 4,483 2,939 110 7,422 — — 7,532 4,183 1983 (1) 7450 Boston Boulevard, Building Three Office Springfield, VA — 1,165 4,681 1,466 1,327 5,985 — — 7,312 3,145 1987 (1) 453 Ravendale Drive Office Mountain View, CA — 5,477 1,090 233 5,477 1,323 — — 6,800 265 1977 (1) 8000 Grainger Court, Building Five Office Springfield, VA — 366 4,282 2,090 453 6,285 — — 6,738 5,225 1984 (1) 7500 Boston Boulevard, Building Six Office Springfield, VA — 138 3,749 2,084 273 5,698 — — 5,971 4,399 1985 (1) 7300 Boston Boulevard, Building Thirteen Office Springfield, VA — 608 4,773 497 608 5,270 — — 5,878 4,586 2002 (1) 7601 Boston Boulevard, Building Eight Office Springfield, VA — 200 878 4,231 378 4,931 — — 5,309 3,719 1986 (1) 8000 Corporate Court, Building Eleven Office Springfield, VA — 136 3,071 1,264 687 3,784 — — 4,471 2,570 1989 (1) 7375 Boston Boulevard, Building Ten Office Springfield, VA — 23 2,685 822 47 3,483 — — 3,530 2,432 1988 (1) 7374 Boston Boulevard, Building Four Office Springfield, VA — 241 1,605 1,352 303 2,895 — — 3,198 2,275 1984 (1) 7451 Boston Boulevard, Building Two Office Springfield, VA — 249 1,542 1,348 535 2,604 — — 3,139 2,173 1982 (1) 32 Hartwell Avenue Office Lexington, MA — 168 1,943 607 168 2,550 — — 2,718 1,674 1968-1979/1987 (1) 164 Lexington Road Office Billerica, MA — 592 1,370 117 592 1,487 — — 2,079 745 1982 (1) 17 Hartwell Avenue Office Lexington, MA — 26 150 457 26 607 — — 633 293 1968 (1) The Avant at Reston Town Center Residential Reston, VA — 20,350 91,995 813 20,350 92,808 — — 113,158 4,833 2014 (1) The Lofts at Atlantic Wharf Residential Boston, MA — 3,529 54,891 1,579 3,529 56,470 — — 59,999 6,596 2011 (1) Boston Marriott Cambridge Hotel Cambridge, MA — 478 37,918 32,774 478 70,692 — — 71,170 47,620 1986 (1) Kendall Center Green Garage (formerly Cambridge Center East Garage) Garage Cambridge, MA — — 35,035 3,840 — 38,875 — — 38,875 8,534 1984 (1) Kendall Center Yellow Garage (formerly Cambridge Center West Garage) Garage Cambridge, MA — 1,256 15,697 859 1,256 16,556 — — 17,812 4,140 2006 (1) Kendall Center Blue Garage (formerly Cambridge Center North Garage) Garage Cambridge, MA — 1,163 11,633 1,105 1,163 12,738 — — 13,901 8,630 1990 (1) Salesforce Tower Development San Francisco, CA — — — 429,767 — — — 429,767 429,767 — N/A N/A 601 Massachusetts Avenue Development Washington, DC — — — 253,166 95,312 140,791 — 17,063 253,166 1,531 N/A N/A 10 CityPoint Development Waltham, MA — — — 70,226 — — — 70,226 70,226 — N/A N/A Reston Signature Site Development Reston, VA — — — 38,886 — — 12,678 26,208 38,886 — N/A N/A Cambridge Residential / 88 Ames Development Cambridge, MA — — — 9,495 — — — 9,495 9,495 — N/A N/A Springfield Metro Center Land Springfield, VA — — — 34,870 — — 34,870 — 34,870 — N/A N/A Tower Oaks Master Plan Land Rockville, MD — — — 29,022 — — 29,022 — 29,022 — N/A N/A Plaza at Almaden Land San Jose, CA — — — 29,010 — — 29,010 — 29,010 — N/A N/A Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2015 (dollars in thousands) Original Costs Capitalized Subsequent to Acquisition Land and Improvements Building and Improvements Land Held for Development Development and Construction in Progress Total Accumulated Depreciation Year(s) Built/ Renovated Depreciable Lives (Years) Property Name Type Location Encumbrances Land Building 6601 & 6605 Springfield Center Drive Land Springfield, VA — — — 13,866 — — 13,866 — 13,866 — N/A N/A 214 Third Avenue Land Waltham, MA — — — 13,415 — 132 13,283 — 13,415 — N/A N/A 103 Fourth Avenue Land Waltham, MA — — — 11,927 — — 11,927 — 11,927 — N/A N/A Reston Gateway Land Reston, VA — — — 10,294 — — 10,294 — 10,294 — N/A N/A 20 CityPoint Land Waltham, MA — — — 10,258 — — 10,258 — 10,258 — N/A N/A Reston Eastgate Land Reston, VA — — — 9,215 — — 9,215 — 9,215 — N/A N/A Washingtonian North Land Gaithersburg, MD — — — 8,836 — — 8,836 — 8,836 — N/A N/A Crane Meadow Land Marlborough, MA — — — 8,727 — — 8,727 — 8,727 — N/A N/A Broad Run Business Park Land Loudoun County, VA — — — 6,399 — — 6,399 — 6,399 — N/A N/A North First Master Plan Land San Jose, CA — — — 2,999 — — 2,999 — 2,999 — N/A N/A Fourth and Harrison (formerly 425 Fourth Street) Land San Francisco, CA — — — 2,920 — — 2,920 — 2,920 — N/A N/A Kendall Center Master Plan (formerly Cambridge Master Plan) Land Cambridge, MA — — — 1,403 — — 1,403 — 1,403 — N/A N/A 30 Shattuck Road Land Andover, MA — — — 1,213 — — 1,213 — 1,213 — N/A N/A $ 3,438,714 (2 ) $ 4,602,809 $ 11,248,289 $ 3,180,191 $ 4,700,793 $ 13,314,366 $ 252,195 $ 763,935 $ 19,031,289 $ 3,826,862 Note: Total Real Estate does not include Furniture, Fixtures and Equipment totaling approximately $29,852 . Accumulated Depreciation does not include approximately $19,954 of accumulated depreciation related to Furniture, Fixtures and Equipment. The aggregate cost and accumulated depreciation for tax purposes was approximately $16.8 billion and $3.4 billion , respectively. (1) Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years. (2) Includes the unamortized balance of the historical fair value adjustment totaling approximately
Activity of Real Estate and Accumulated Depreciation [Table Text Block]	A summary of activity for real estate and accumulated depreciation is as follows: 2015 2014 2013 Real Estate: Balance at the beginning of the year $ 18,786,572 $ 18,523,277 $ 14,431,521 Additions to/improvements of real estate 700,792 594,296 4,410,622 Assets sold/written-off (456,075 ) (331,001 ) (318,866 ) Balance at the end of the year $ 19,031,289 $ 18,786,572 $ 18,523,277 Accumulated Depreciation: Balance at the beginning of the year $ 3,458,640 $ 3,081,040 $ 2,862,302 Depreciation expense 478,457 447,667 411,860 Assets sold/written-off (110,235 ) (70,067 ) (193,122 ) Balance at the end of the year $ 3,826,862 $ 3,458,640 $ 3,081,040 Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

Organization (Details)

Organization (Details) ft² in Millions	12 Months Ended
	Dec. 31, 2015ft²aReal_Estate_Propertiesyrshares	Dec. 31, 2014shares
Real Estate Properties [Line Items]
Restriction on redemption of OP units from date of issuance (years) | yr	1
One OP unit is equivalent to one share of Common Stock (in shares) | shares	1
OP unit conversion rate (in shares) | shares	1
Number Of series Of preferred units outstanding	1
Area of undeveloped land parcels owned (in acres) | a	457.1
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	168
Net Rentable Area | ft²	46.5
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	11
Net Rentable Area | ft²	4.6
Total Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	158
Class A Office Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	127
Office Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	9
Office Technical Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	31
Hotel Property [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	1
Retail Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	5
Residential Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	4
Residential Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties	2
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Real Estate Properties [Line Items]
Preferred stock / units, shares / units outstanding (in shares / units) | shares	80,000	80,000
Preferred Stock, Dividend Rate, Percentage	5.25%
Depositary shares of Series B Cumulative Redeemable Preferred [Member]
Real Estate Properties [Line Items]
Preferred stock / units, shares / units outstanding (in shares / units) | shares	8,000,000
Series B Preferred Units [Member]
Real Estate Properties [Line Items]
Preferred stock / units, shares / units outstanding (in shares / units) | shares	80,000
Boston Properties, Inc. [Member]
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)	89.50%	89.50%

Summary Of Significant Accoun47

Summary Of Significant Accounting Policies (Narrative) (Details)	Jul. 31, 2015yr	Dec. 31, 2015USD ($)yr	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Entity Information [Line Items]
Probable Sale Term of Property After Classified As Held For Sale (Years) | yr		1
Maximum Period After Construction The Company Considers A Construction Project As Substantially Completed (In Years) | yr		1
Interest costs capitalized		$ 34,213,000	$ 52,476,000	$ 68,152,000
Salaries And Related Costs Capitalized		10,400,000	8,500,000	7,700,000
Cash FDIC Insured Limit		250,000
Separate Unrestricted Cash For Deferred Compensation Plan.		20,400,000	19,500,000
Gains (losses) from investments in securities		(653,000)	1,038,000	2,911,000
Internal Leasing Salaries And Related Costs Capitalized		5,500,000	6,000,000	5,100,000
Straight-line rent adjustments		(80,000,000)	(63,100,000)	(65,800,000)
Above and below market rent adjustments, net		$ 35,900,000	48,300,000	28,000,000
Ground Lease Expiration Date, Maximum		2,114
REIT Annual Taxable Income Distribution Requirement Percentage, Minimum		90.00%
Boston Properties Limited Partnership [Member]
Entity Information [Line Items]
Interest costs capitalized		$ 34,213,000	52,476,000	68,152,000
Gains (losses) from investments in securities		(653,000)	1,038,000	$ 2,911,000
Net Difference Between Tax Basis And Company's Assets And Liabilities.		$ 2,600,000,000	1,400,000,000
Boston Properties, Inc. [Member]
Entity Information [Line Items]
Company Annual Taxable Income Distribution Percentage		100.00%
Net Difference Between Tax Basis And Company's Assets And Liabilities.		$ 1,600,000,000	$ 2,200,000,000
Clarendon Garage [Member]
Entity Information [Line Items]
Ground Lease Term (in years) | yr	99	99
Operating Leases, Future Minimum Payments Due		$ 28,900,000

Summary Of Significant Accoun48

Summary Of Significant Accounting Policies Schedule of Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2015
Land Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	25 years
Land Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	40 years
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	10 years
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	40 years
Tenant Improvement [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, description	Shorter of useful life or terms of related lease
Furniture, fixtures and equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	3 years
Furniture, fixtures and equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	7 years

Summary Of Significant Accoun49

Summary Of Significant Accounting Policies Schedule of Finite Lived Intangible Assets Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2015USD ($)
Finite-Lived Intangible Assets [Line Items]
2,016	$ 52,456
2,017	36,438
2,018	31,913
2,019	26,067
2,020	13,325
Acquired Above-Market Lease Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
2,016	14,210
2,017	11,756
2,018	8,637
2,019	7,106
2,020	5,400
Acquired Below-Market Lease Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
2,016	43,809
2,017	33,112
2,018	31,272
2,019	26,434
2,020	$ 9,852

Summary Of Significant Accoun50

Summary Of Significant Accounting Policies Schedule Of Future Contractual Minimum Lease Payments Under Non-Cancelable Ground Leases (Details) $ in Thousands	Dec. 31, 2015USD ($)
Summary of Significant Accounting Policies [Abstract]
2,016	$ 15,188
2,017	30,658
2,018	11,507
2,019	9,693
2,020	9,870
Thereafter	$ 594,701

Summary Of Significant Accoun51

Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	$ 3,438,714	$ 4,309,484
Mezzanine notes payable	308,482	309,796
Unsecured senior notes	5,289,317	5,287,704
Total	3,358,479
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	3,438,714	4,309,484
Mezzanine notes payable	308,482	309,796
Unsecured senior notes	5,289,317	5,287,704
Total	9,036,513	9,906,984
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable	3,503,746	4,449,541
Mezzanine notes payable	306,103	306,156
Unsecured senior notes	5,547,738	5,645,819
Total	$ 9,357,587	$ 10,401,516

Summary Of Significant Accoun52

Summary Of Significant Accounting Policies Schedule of Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes (Details) - $ / shares		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013		Jan. 28, 2016	Jan. 28, 2015
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share	[1]							$ 1.90
Special dividend (per share amount)								$ 1.25	$ 4.50
Boston Properties, Inc. [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Special dividend (per share amount)		$ 1.25		$ 4.50		$ 2.25
Dividends Treatment For Federal Tax Purposes, Percentage		100.00%		100.00%		100.00%
Dividends treatment for federal tax purposes.		$ 4.04	[2]	$ 6.82	[3]	$ 4.75	[4]
Boston Properties, Inc. [Member] | Dividend Declared [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share		1.90		5.15		2.90
Boston Properties, Inc. [Member] | non-special dividend [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share		0.65		0.65		0.65
Boston Properties, Inc. [Member] | Allocated to fiscal 2013[Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share						2.44
Boston Properties, Inc. [Member] | Allocated to fiscal 2014 [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share				4.41		$ 0.46
Boston Properties, Inc. [Member] | Allocated to fiscal 2015 [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Payable, Amount Per Share				$ 0.74
Special dividend (per share amount)		1.35
Boston Properties, Inc. [Member] | Allocated to fiscal 2016 [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Special dividend (per share amount)		$ 0.55
Boston Properties, Inc. [Member] | Capital Gains Income [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Treatment For Federal Tax Purposes, Percentage		42.03%		100.00%		51.29%
Dividends treatment for federal tax purposes.		$ 1.70		$ 6.82		$ 2.44
Boston Properties, Inc. [Member] | Ordinary Income [Member]
Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]
Dividends Treatment For Federal Tax Purposes, Percentage		57.97%		0.00%		48.71%
Dividends treatment for federal tax purposes.		$ 2.34		$ 0		$ 2.31
[1]	Includes a special dividend/distribution of $1.25 per share/common unit.
[2]	The fourth quarter 2015 dividend of $1.90 per common share consists of a $1.25 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $1.35 per common share was allocable to 2015 and approximately $0.55 per common share is allocable to 2016.
[3]	The fourth quarter 2014 dividend of $5.15 per common share consists of a $4.50 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $4.41 per common share was allocable to 2014 and approximately $0.74 per common share is allocable to 2015.
[4]	The fourth quarter 2013 dividend of $2.90 per common share consists of a $2.25 per common share special dividend and a $0.65 per common share regular quarterly dividend, approximately $2.44 per common share was allocable to 2013 and approximately $0.46 per common share is allocable to 2014.

Summary Of Significant Accoun53

Summary Of Significant Accounting Policies GAAP Reconciliation Of Net Income To Taxable Income (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Entity Information [Line Items]
Net income attributable to the Company		$ 137,851	$ 184,082	$ 79,460	$ 171,182	$ 174,510	$ 127,724	$ 76,527	$ 54,034	$ 583,106	$ 443,611		$ 749,811
Straight line rent and net above and below-market rent adjustments										(92,483)	(91,733)		(74,445)
Book/tax differences from depreciation and amortization										307,115	239,681		170,370
Book/Tax differences from interest expense										(43,349)	(43,148)		(7,912)
Book/tax differences on gains/(losses) from capital transactions										(74,482)	943,778	[1]	(124,413)
Book/tax differences from stock-based compensation										22,008	32,483		42,146
Tangible Property Regulations	[2]									(74,887)	(442,650)		0
Other book/tax differences, net										(15,259)	(7,945)		(4,885)
Taxable Income										611,769	1,074,077		750,672
One-time deduction for Tangible Repair Regulations											385,600
Boston Properties Limited Partnership [Member]
Entity Information [Line Items]
Net income attributable to the Company		$ 156,901	$ 207,626	$ 90,852	$ 193,369	$ 204,759	$ 144,715	$ 87,436	$ 62,219	659,248	509,629		849,573
Straight line rent and net above and below-market rent adjustments										(103,227)	(102,319)		(82,904)
Book/tax differences from depreciation and amortization										329,629	253,590		174,384
Book/Tax differences from interest expense										(48,385)	(48,128)		(8,811)
Book/tax differences on gains/(losses) from capital transactions										(67,602)	1,065,518	[3]	(138,300)
Book/tax differences from stock-based compensation										24,565	36,232		46,935
Tangible Property Regulations	[4]									(83,587)	(493,731)		0
Other book/tax differences, net										(14,561)	(11,403)		8,589
Taxable Income										$ 696,080	1,209,388		$ 849,466
One-time deduction for Tangible Repair Regulations											$ 430,100
[1]	Consists primarily of the gain on sale of real estate for tax purposes related to the October 2014 sale by the Company of a 45% interest in each of 601 Lexington Avenue in New York City and Atlantic Wharf Office Building and 100 Federal Street in Boston, which was accounted for as an equity transaction for GAAP purposes with no gain on sale of real estate recognized
[2]	In September 2013, the Internal Revenue Service released final Regulations governing when taxpayers like Boston Properties, Inc. must capitalize and depreciate costs for acquiring, maintaining, repairing and replacing tangible property and when taxpayers can deduct such costs. These final Regulations were effective for tax years beginning on or after January 1, 2014. These Regulations permitted Boston Properties, Inc. to deduct certain types of expenditures that were previously required to be capitalized. The Regulations also allowed Boston Properties, Inc. to make a one-time election in 2014 to immediately deduct certain amounts that were capitalized in previous years that are not required to be capitalized under the new Regulations. The one-time deduction included above totaled approximately $385.6 million for the year ended December 31, 2014.
[3]	Consists primarily of the gain on sale of real estate for tax purposes related to the October 2014 sale by the Company of a 45% interest in each of 601 Lexington Avenue in New York City and Atlantic Wharf Office Building and 100 Federal Street in Boston, which was accounted for as an equity transaction for GAAP purposes with no gain on sale of real estate recognized
[4]	In September 2013, the Internal Revenue Service released final Regulations governing when taxpayers like Boston Properties Limited Partnership must capitalize and depreciate costs for acquiring, maintaining, repairing and replacing tangible property and when taxpayers can deduct such costs. These final Regulations were effective for tax years beginning on or after January 1, 2014. These Regulations permitted Boston Properties Limited Partnership to deduct certain types of expenditures that were previously required to be capitalized. The Regulations also allowed Boston Properties Limited Partnership to make a one-time election in 2014 to immediately deduct certain amounts that were capitalized in previous years that are not required to be capitalized under the new Regulations. The one-time deduction included above totaled approximately $430.1 million for the year ended December 31, 2014.

Real Estate Schedule of Real Es

Real Estate Schedule of Real Estate Properties (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Real Estate Properties [Line Items]
Land	$ 4,806,021	$ 4,785,772
Land held for future development	252,195	268,114
Buildings and improvements	11,709,285	11,666,105
Tenant improvements	1,920,247	1,752,115
Furniture, fixtures and equipment	29,852	27,986
Construction in progress	763,935	736,311
Total	19,481,535	19,236,403
Less: accumulated depreciation	(3,925,894)	(3,547,659)
Total real estate	15,555,641	15,688,744
Boston Properties Limited Partnership [Member]
Real Estate Properties [Line Items]
Land	4,700,793	4,680,181
Land held for future development	252,195	268,114
Buildings and improvements	11,394,119	11,349,851
Tenant improvements	1,920,247	1,752,115
Furniture, fixtures and equipment	29,852	27,986
Construction in progress	763,935	736,311
Total	19,061,141	18,814,558
Less: accumulated depreciation	(3,846,816)	(3,476,321)
Total real estate	$ 15,214,325	$ 15,338,237

Real Estate (Narrative) (Detail

Real Estate (Narrative) (Details) $ in Thousands	Dec. 17, 2015USD ($)ft²aspacesBuildings	Oct. 01, 2015USD ($)a	Sep. 18, 2015USD ($)ft²	Aug. 13, 2015USD ($)ft²	Jul. 31, 2015USD ($)yr	Mar. 17, 2015USD ($)ft²apartments	Feb. 19, 2015USD ($)a	May. 31, 2013USD ($)ft²partners	Apr. 10, 2013USD ($)ft²Buildings	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Mar. 16, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Sep. 17, 2015USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)yr	Dec. 16, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 02, 2015ft²	Nov. 01, 2015ft²	Sep. 10, 2015ft²	Aug. 14, 2015ft²	Jul. 23, 2015ft²apartments	May. 01, 2015ft²
Real Estate Properties [Line Items]
Gain on consolidation of joint ventures																						$ 0		$ 0	$ 385,991
Payments to Acquire and Develop Real Estate																						0		4,670	522,900
Total revenue										$ 624,240	$ 629,884	$ 618,221	$ 618,476		$ 613,707	$ 618,803	$ 589,794	$ 574,694				2,490,821		2,396,998	2,135,539
Earnings																						849,365		801,822	678,120
Proceeds from sales of real estate																						602,600		419,864	250,078
Impairment loss																						0		0	8,306
Gains on sales of real estate																						$ 375,895		168,039	0
Mountain View Research And Technology Parks [Member]
Real Estate Properties [Line Items]
Gain on consolidation of joint ventures									$ 26,500
Total revenue																					$ 16,700
Earnings																					$ 400
Aggregate purchase price									$ 233,084
Mountain View Research Park
Real Estate Properties [Line Items]
Number of real estate properties | Buildings									16
Net Rentable Area | ft²									604,000
Mountain View Technology [Member]
Real Estate Properties [Line Items]
Number of real estate properties | Buildings									7
Net Rentable Area | ft²									135,000
767 Fifth Avenue (the General Motors Building)
Real Estate Properties [Line Items]
Gain on consolidation of joint ventures								$ 359,500
Total revenue																			$ 168,400
Earnings																			$ 8,400
Net Rentable Area | ft²								1,800,000
Number of Joint Venture Partners | partners								2
Ownership Percentage								40.00%
Washingtonian North land parcel [Member]
Real Estate Properties [Line Items]
Proceeds from sales of real estate		$ 13,800					$ 8,400
Sale Price Of Sold Property		$ 13,300					$ 8,700
Area of Land | a		18.3					27
Gains on sales of real estate		$ 2,000					$ 3,500
Land sold (in acres) | a		5.8					8.5
Innovation Place [Member]
Real Estate Properties [Line Items]
Earnings																							$ (3,500)	(3,100)	400
Proceeds from sales of real estate	$ 199,300
Net Rentable Area | ft²	574,000
Parking spaces | spaces	1,699
Sale Price Of Sold Property	$ 207,000
Area of Land | a	26
Gains on sales of real estate	$ 79,100
Residences on The Avenue [Member]
Real Estate Properties [Line Items]
Earnings														$ 1,100										2,700	4,400
Proceeds from sales of real estate						$ 192,500
Sale Price Of Sold Property						$ 196,000
Number of apartment units | apartments						335
Gains on sales of real estate						$ 91,400
Rental revenue supoprt payments to buyer maximum						$ 6,000
505 9th Street [Member] | Consolidated Properties [Member]
Real Estate Properties [Line Items]
Earnings																				$ 2,300				2,300	1,900
Ownership Percentage by Parent			50.00%
Proceeds from sales of real estate			$ 194,600
Net Rentable Area | ft²			322,000
Sale Price Of Sold Property			$ 318,000
Mortgage Loan Related to Property Sales			117,000
Gains on sales of real estate			199,500
Reservoir Place North [Member]
Real Estate Properties [Line Items]
Net Rentable Area | ft²																															73,000
Cambridge Residential / 88 Ames
Real Estate Properties [Line Items]
Net Rentable Area | ft²																														164,000
Area of Land | ft²				8,700
Number of apartment units | apartments																														274
Payments to Acquire Land				$ 2,000
Reston Signature Site
Real Estate Properties [Line Items]
Net Rentable Area | ft²																														514,000
Number of apartment units | apartments																														508
601 Massachusetts Avenue
Real Estate Properties [Line Items]
Net Rentable Area | ft²																													478,000
690 Folsom Street
Real Estate Properties [Line Items]
Net Rentable Area | ft²																										26,000
The Point (formerly 99 Third Avenue Retail)
Real Estate Properties [Line Items]
Net Rentable Area | ft²																												16,000
535 Mission Street
Real Estate Properties [Line Items]
Net Rentable Area | ft²																											307,000
Retail Site [Member] | Residences on The Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area | ft²						50,000
Retail Site [Member] | Cambridge Residential / 88 Ames
Real Estate Properties [Line Items]
Net Rentable Area | ft²																														9,000
Retail Site [Member] | Reston Signature Site
Real Estate Properties [Line Items]
Net Rentable Area | ft²																														24,000
Occupied [Member] | Innovation Place [Member]
Real Estate Properties [Line Items]
Number of real estate properties | Buildings	1
Vacant [Member] | Innovation Place [Member]
Real Estate Properties [Line Items]
Number of real estate properties | Buildings	3
Net Rentable Area | ft²	463,000
Future potential [Member] | Innovation Place [Member]
Real Estate Properties [Line Items]
Net Rentable Area | ft²	537,000
Parking structures | Buildings	2
Parking spaces | spaces	3,000
Clarendon Garage [Member]
Real Estate Properties [Line Items]
Ground Lease Term (in years) | yr					99																	99
Operating Lease Ground Rent Expense					$ 5,000
Maximum [Member] | Clarendon Garage [Member]
Real Estate Properties [Line Items]
Operating Lease Ground Rent Expense					$ 37,000
Previous ground lease remaining term [Member] | Clarendon Garage [Member]
Real Estate Properties [Line Items]
Ground Lease Term (in years) | yr					45
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] | 505 9th Street [Member] | Consolidated Properties [Member]
Real Estate Properties [Line Items]
Proceeds from sales of real estate			97,300
Gains on sales of real estate			101,100
Boston Properties Limited Partnership [Member]
Real Estate Properties [Line Items]
Gain on consolidation of joint ventures																						$ 0		0	385,991
Payments to Acquire and Develop Real Estate																						0		4,670	522,900
Total revenue										$ 624,240	$ 629,884	$ 618,221	$ 618,476		$ 613,707	$ 618,803	$ 589,794	$ 574,694				2,490,821		2,396,998	2,135,539
Earnings																						857,358		810,331	690,073
Proceeds from sales of real estate																						602,600		419,864	250,078
Impairment loss																						0		0	4,401
Gains on sales of real estate																						$ 377,093		$ 174,686	$ 0
Boston Properties Limited Partnership [Member] | Innovation Place [Member]
Real Estate Properties [Line Items]
Gains on sales of real estate	$ 80,100
Boston Properties Limited Partnership [Member] | 505 9th Street [Member] | Consolidated Properties [Member]
Real Estate Properties [Line Items]
Gains on sales of real estate			$ 199,700

Real Estate (Summary Of The Dis

Real Estate (Summary Of The Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue	$ 624,240	$ 629,884	$ 618,221	$ 618,476	$ 613,707	$ 618,803	$ 589,794	$ 574,694	$ 2,490,821	$ 2,396,998	$ 2,135,539
Expenses
Depreciation and amortization									639,542	628,573	560,637
Total expenses									1,641,456	1,595,176	1,457,419
Operating income									849,365	801,822	678,120
Other Expenses
Interest expense									432,196	455,743	446,880
Noncontrolling interest in income (loss) from discontinued operations - common units of the Operating Partnership									0	0	(14,151)
Income from discontinued operations attributable to Boston Properties, Inc.											123,641
Gain on sale of real estate from discontinued operations									0	0	112,829
Gain on forgiveness of debt from discontinued operations									0	0	20,182
Impairment loss from discontinued operations									0	0	(3,241)
Boston Properties Limited Partnership [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue	$ 624,240	$ 629,884	$ 618,221	$ 618,476	$ 613,707	$ 618,803	$ 589,794	$ 574,694	2,490,821	2,396,998	2,135,539
Expenses
Depreciation and amortization									631,549	620,064	552,589
Total expenses									1,633,463	1,586,667	1,445,466
Operating income									857,358	810,331	690,073
Other Expenses
Interest expense									432,196	455,743	446,880
Income from discontinued operations attributable to Boston Properties, Inc.											141,365
Gain on sale of real estate from discontinued operations									0	0	115,459
Gain on forgiveness of debt from discontinued operations									0	0	20,736
Impairment loss from discontinued operations									$ 0	$ 0	(2,852)
Montvale Center, 303 Almaden Blvd, 1301 New York Avenue, One Preserve Parkway and 10 & 20 Burlington Mall Road [Member] | Boston Properties, Inc. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue											20,138
Expenses
Operating											6,996
Depreciation and amortization											4,760
Total expenses											11,756
Operating income											8,382
Other Expenses
Interest expense											360
Income from discontinued operations											8,022
Noncontrolling interest in income (loss) from discontinued operations - common units of the Operating Partnership											(803)
Income from discontinued operations attributable to Boston Properties, Inc.											7,219
Gain on sale of real estate from discontinued operations											112,829
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											(13,348)
Gain on sale of real estate, gain on forgiveness of debt and impairment loss from discontinued operations attributable to Boston Properties, Inc											116,422
Montvale Center, 303 Almaden Blvd, 1301 New York Avenue, One Preserve Parkway and 10 & 20 Burlington Mall Road [Member] | Boston Properties Limited Partnership [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue											20,138
Expenses
Operating											6,996
Depreciation and amortization											4,760
Total expenses											11,756
Operating income											8,382
Other Expenses
Interest expense											360
Income from discontinued operations											8,022
Gain on sale of real estate from discontinued operations											115,459
Gain on forgiveness of debt from discontinued operations											20,736
Impairment loss from discontinued operations											$ (2,852)

Real Estate (Pro Forma In Conne

Real Estate (Pro Forma In Connection With Acquisition) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2013USD ($)$ / shares
Real Estate Properties [Line Items]
Total revenue	$ 2,257,098
Income from continuing operations	302,354
Net income attributable to the Company	$ 400,017
Basic earnings per share / unit: Net income per share / unit attributable to the Company (in dollars per share / unit) | $ / shares	$ 2.58
Diluted earnings per share / unit: Net income per share / unit attributable to the Company(in dollars per share / unit) | $ / shares	$ 2.57
Boston Properties Limited Partnership [Member]
Real Estate Properties [Line Items]
Total revenue	$ 2,257,098
Income from continuing operations	314,307
Net income attributable to the Company	$ 452,813
Basic earnings per share / unit: Net income per share / unit attributable to the Company (in dollars per share / unit) | $ / shares	$ 2.68
Diluted earnings per share / unit: Net income per share / unit attributable to the Company(in dollars per share / unit) | $ / shares	$ 2.67

Real Estate (Schedule Of Alloca

Real Estate (Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition) (Details) - USD ($) $ in Thousands		May. 31, 2013	Apr. 10, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Real estate and related intangibles recorded upon consolidation				$ 0	$ 0	$ 3,356,000
Mortgage notes payable				(3,438,714)	(4,309,484)
Mezzanine notes payable				(308,482)	(309,796)
Outside members' notes payable				(180,000)	(180,000)
Debt recorded upon consolidation				0	0	(2,056,000)
Cash and cash equivalents					0	79,468
Accrued interest payable				(190,386)	(163,532)
Working capital recorded upon consolidation				0	0	(177,315)
Noncontrolling interest in property partnerships recorded upon consolidation				$ 0	$ 0	$ (480,861)
Mountain View Research And Technology Parks [Member]
Restructuring Cost and Reserve [Line Items]
Land			$ 126,521
Building and improvements			82,451
Tenant Improvements			7,326
In-place lease Intangibles			23,279
Above market rents			843
Below market rents			(7,336)
Aggregate purchase price			$ 233,084
767 Fifth Avenue (the General Motors Building)
Restructuring Cost and Reserve [Line Items]
Land		$ 1,796,252
Building and improvements		1,447,446
Tenant Improvements		85,208
In-place lease Intangibles		357,781
Above market rents		101,897
Below market rents		(239,641)
Above Market Assumed Debt Adjustments		(192,943)
Real estate and related intangibles recorded upon consolidation		3,356,000
Mortgage notes payable		(1,300,000)
Mezzanine notes payable		(306,000)
Outside members' notes payable	[1]	(450,000)
Debt recorded upon consolidation		(2,056,000)
Cash and cash equivalents		79,468
Cash held in escrows		2,403
Tenant and other receivables		7,104
Prepaid expenses and other assets		4,269
Accounts payable and accrued expenses		(2,418)
Accrued interest payable	[2]	(182,369)
Other liabilities		(6,304)
Working capital recorded upon consolidation		(97,847)
Noncontrolling Interest		(520,000)
Noncontrolling Interest working capital		39,139
Noncontrolling interest in property partnerships recorded upon consolidation		(480,861)
Net Assets Recorded Upon Consolidation		721,292
Consolidation, Eliminations [Member] | 767 Fifth Avenue (the General Motors Building)
Restructuring Cost and Reserve [Line Items]
Outside members' notes payable		(270,000)
Accrued interest payable		$ (105,500)
[1]	The Company’s member loan totaling $270.0 million eliminates in consolidation.
[2]	The Company’s share of the accrued interest payable on the members’ loans totaling approximately $105.5 million eliminates in consolidation.

Deferred Charges (Details)

Deferred Charges (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred Charges [Abstract]
Leasing costs, including lease related intangibles	$ 1,123,105	$ 1,234,192
Financing costs	61,402	69,127
Deferred charges, gross	1,184,507	1,303,319
Less: Accumulated amortization	(451,670)	(471,575)
Deferred charges, total	$ 732,837	$ 831,744

Deferred Charges Schedule of Ac

Deferred Charges Schedule of Acquired In-Place Lease Intangibles (Details) $ in Thousands	Dec. 31, 2015USD ($)
Deferred Charges [Abstract]
2,016	$ 52,456
2,017	36,438
2,018	31,913
2,019	26,067
2,020	$ 13,325

Investments in Unconsolidated61

Investments in Unconsolidated Joint Ventures (Investments in Unconsolidated Joint Ventures) (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2015USD ($)ft²Land_ParcelsBuildingspayments	Dec. 31, 2014USD ($)
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures		$ 235,224	$ 193,394
Investments In Affiliates Subsidiaries Associates And Joint Ventures net	[1]	210,023	182,042
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated joint ventures		$ (25,200)	(11,400)
Square 407 Limited Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Market Square North
Ownership Percentage		50.00%
Investments in unconsolidated joint ventures	[1]	$ (9,951)	(8,022)
The Metropolitan Square Associates LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Metropolitan Square
Ownership Percentage		51.00%
Investments in unconsolidated joint ventures	[1]	$ 9,179	8,539
BP/CRF 901 New York Avenue LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		901 New York Avenue
Ownership Percentage	[2]	25.00%
Investments in unconsolidated joint ventures	[1]	$ (11,958)	(1,080)
WP Project Developer LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Wisconsin Place Land and Infrastructure
Ownership Percentage	[3]	33.30%
Investments in unconsolidated joint ventures	[1]	$ 43,524	45,514
Annapolis Junction NFM, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Annapolis Junction
Ownership Percentage	[4]	50.00%
Number of real estate properties | Buildings		4
Parcels of undeveloped land | Land_Parcels		2
Investments in unconsolidated joint ventures	[1]	$ 29,009	25,246
540 Madison Venture LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		540 Madison Avenue
Ownership Percentage		60.00%
Investments in unconsolidated joint ventures	[1]	$ 68,983	68,128
500 North Capitol LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		500 North Capitol Street, NW
Ownership Percentage		30.00%
Investments in unconsolidated joint ventures	[1]	$ (3,292)	(2,250)
501 K Street LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		1001 6th Street
Ownership Percentage	[5]	50.00%
Investments in unconsolidated joint ventures	[1]	$ 42,584	41,736
Potential additonal payments to joint venture partner | payments		2
Minimum square footage to make a potential additional payment to joint venture partner (in sqft) | ft²		520,000
Podium Developer LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		The Hub on Causeway
Ownership Percentage		50.00%
Investments in unconsolidated joint ventures	[1]	$ 18,508	$ 4,231
Entity Owning Land And Infrastructure Of Project [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		33.30%
1265 Main Office JV LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		1265 Main Street
Ownership Percentage		50.00%
Investments in unconsolidated joint ventures	[1]	$ 11,916
BNY Tower Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Dock72 at the Brooklyn Navy Yard
Ownership Percentage		50.00%
Investments in unconsolidated joint ventures	[1]	$ 11,521
[1]	Investments with deficit balances aggregating approximately $25.2 million and $11.4 million at December 31, 2015 and 2014, respectively, have been reflected within Other Liabilities on the Company's Consolidated Balance Sheets.
[2]	The Company’s economic ownership has increased based on the achievement of certain return thresholds.
[3]	The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land, parking garage and infrastructure of the project.
[4]	The joint venture owns four in-service buildings and two undeveloped land parcels
[5]	Under the joint venture agreement, the partner may be entitled to up to two additional payments from the venture based on increases in total square footage of the project above 520,000 square feet and achieving certain project returns at stabilization.

Investments in Unconsolidated62

Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
ASSETS
Real estate and development in process, net		$ 15,555,641	$ 15,688,744
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable		3,438,714	4,309,484
Other liabilities		483,601	502,255
Total liabilities and equity / capital		18,379,456	19,886,767
Carrying value of the Company's investments in unconsolidated joint ventures		235,224	193,394
Unconsolidated Joint Ventures [Member]
ASSETS
Real estate and development in process, net		1,072,412	1,034,552
Other assets		256,055	264,097
Total assets		1,328,467	1,298,649
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Mortgage and notes payable		833,895	830,075
Other liabilities		44,549	34,211
Members'/Partners' equity		450,023	434,363
Total liabilities and equity / capital		1,328,467	1,298,649
Company's share of equity		237,070	209,828
Basis differentials	[1]	(27,047)	(27,786)
Carrying value of the Company's investments in unconsolidated joint ventures	[2]	210,023	182,042
Unconsolidated Joint Ventures [Member]
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY
Carrying value of the Company's investments in unconsolidated joint ventures		$ (25,200)	$ (11,400)
[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.
[2]	Investments with deficit balances aggregating approximately $25.2 million and $11.4 million at December 31, 2015 and 2014, respectively, have been reflected within Other Liabilities on the Company's Consolidated Balance Sheets.

Investments in Unconsolidated63

Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Mortgage notes payable		$ 3,438,714				$ 4,309,484				$ 3,438,714		$ 4,309,484
Total revenue		624,240	$ 629,884	$ 618,221	$ 618,476	613,707	$ 618,803	$ 589,794	$ 574,694	2,490,821		2,396,998	$ 2,135,539
Expenses
Depreciation and amortization										639,542		628,573	560,637
Total expenses										1,641,456		1,595,176	1,457,419
Operating income										849,365		801,822	678,120
Other income (expense)
Interest expense										(432,196)		(455,743)	(446,880)
(Losses) gains from early extinguishments of debt										(22,040)		(10,633)	122
Income (loss) from continuing operations		85,406	$ 123,792	$ 100,739	$ 114,086	85,323	$ 109,038	$ 95,901	$ 67,756	424,023		358,018	703,648
Net income (loss)										799,918		526,057	841,440
Income from unconsolidated joint ventures										22,770		12,769	75,074
Straight-line rent adjustments										80,000		63,100	65,800
Above and below market rent adjustments, net										35,900		48,300	28,000
Proceeds from Sale of Equity Method Investments										24,527		1,491	225,862
Gain on consolidation of joint ventures										0		0	385,991
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Mortgage notes payable		833,895				$ 830,075				833,895		830,075
Total revenue	[1]									155,642		158,161	311,548
Expenses
Operating										65,093		62,974	105,319
Depreciation and amortization										36,057		37,041	86,088
Total expenses										101,150		100,015	191,407
Operating income										54,492		58,146	120,141
Other income (expense)
Interest expense										(32,176)		(31,896)	(112,535)
(Losses) gains from early extinguishments of debt										0		0	(1,677)
Income (loss) from continuing operations										22,316		26,250	5,929
Gains on sale of real estate										0		0	14,207
Net income (loss)										22,316		26,250	20,136
Company's share of net income (loss)										22,031	[2]	11,913	4,612
Gains on sale of real estate										0		0	54,501
Basis differential										739		856	(1,017)
Elimination of inter-entity interest on partner loan										0		0	16,978
Income from unconsolidated joint ventures										22,770		12,769	75,074
Straight-line rent adjustments										3,900		3,000	7,800
Above and below market rent adjustments, net										(200)		(100)	33,700
Gain on consolidation of joint ventures										0		$ 0	$ 385,991
BP/CRF 901 New York Avenue LLC [Member]
Schedule of Equity Method Investments [Line Items]
Mortgage notes payable		$ 225,000								225,000
Other income (expense)
Proceeds from Sale of Equity Method Investments										$ 24,500
[1]	Includes straight-line rent adjustments of $3.9 million, $3.0 million and $7.8 million for the years ended December 31, 2015, 2014 and 2013, respectively. Includes net above-/below-market rent adjustments of $(0.2) million, $(0.1) million and $33.7 million for the years ended December 31, 2015, 2014 and 2013, respectively.
[2]	During the year ended December 31, 2015, the Company received a distribution of approximately $24.5 million, which was generated from the excess loan proceeds from the refinancing of 901 New York Avenue’s mortgage loan to a new 10-year mortgage loan totaling $225.0 million. The Company’s allocation of income and distributions for the year ended December 31 2015 was not proportionate to its nominal ownership interest as a result of the achievement of specified investment return thresholds, as provided for in the joint venture agreement.

Investment in unconsolidated Jo

Investment in unconsolidated Joint Ventures (Narrative) (Details) $ in Thousands	Jun. 26, 2015USD ($)ft²yr	May. 08, 2015USD ($)ft²yr	May. 31, 2013partners	Sep. 30, 2015USD ($)ft²	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 22, 2015ft²	Oct. 22, 2015ft²	Sep. 22, 2015ft²
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Equity Method Investments					$ 38,207	$ 52,052	$ 0
Gains (losses) from early extinguishments of debt					(22,040)	(10,633)	122
Repayments of Secured Debt					54,801	87,758	80,311
Gain on consolidation of joint ventures					$ 0	$ 0	$ 385,991
1265 Main Office JV LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage					50.00%
Net Rentable Area | ft²		115,000
Term of Lease Signed (in years) | yr		15
Portion of Building Leased (percentage)		100.00%
767 Fifth Avenue (the General Motors Building)
Schedule of Equity Method Investments [Line Items]
Number of Joint Venture Partners | partners			2
Annapolis Junction Building Eight [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage								50.00%
Net Rentable Area | ft²								126,000
Annapolis Junction Building Seven [Member]
Schedule of Equity Method Investments [Line Items]
Net Rentable Area | ft²										127,000
BNY Tower Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage					50.00%
Net Rentable Area | ft²	670,000
Term of Lease Signed (in years) | yr	20
Square Footage Of Signed Lease | ft²	222,000
BNY Tower Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Non refundable option payment	$ 1,000
Annapolis Junction Building Six [Member]
Schedule of Equity Method Investments [Line Items]
Net Rentable Area | ft²				119,000
Construction Loan Facility Borrowing Capacity				$ 15,900
Debt Instrument, Basis Spread on Variable Rate				2.25%
Construction Loan				$ 13,400
Hub on Causeway [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage									50.00%
Net Rentable Area | ft²									385,000
joint venture partner [Member] | 1265 Main Office JV LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%
Payments to Acquire Equity Method Investments		$ 9,400
joint venture partner [Member] | BNY Tower Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%
Payments to Acquire Equity Method Investments	$ 9,100
Company [Member] | 1265 Main Office JV LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%
Company [Member] | Annapolis Junction Building Seven [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage										50.00%
Company [Member] | BNY Tower Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%
Payments to Acquire Equity Method Investments	$ 9,100
Company [Member] | Annapolis Junction Building Six [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage				50.00%
Maximum [Member] | BNY Tower Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ground Lease Term (in years) | yr	96
Maximum [Member] | BNY Tower Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Net Rentable Area | ft²	1,000,000
Maximum [Member] | Company [Member] | 1265 Main Office JV LLC [Member]
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Equity Method Investments		$ 9,400
Minimum [Member] | BNY Tower Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ground Lease Term (in years) | yr	46
Minimum [Member] | BNY Tower Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Net Rentable Area | ft²	600,000

Mortgage Notes Payable Schedu65

Mortgage Notes Payable Schedule Of Aggregate Principal Payments On Mortgage Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Mortgage Notes Payable [Abstract]
2,016	$ 576,864
2,017	2,067,654
2,018	18,633
2,019	19,670
2,020	20,766
Thereafter	654,892
Total	3,358,479
Unamortized balance of historical fair value adjustments	80,235
Total carrying value of mortgage notes payable	$ 3,438,714	$ 4,309,484

Mortgage Notes Payable (Narrati

Mortgage Notes Payable (Narrative) (Details) $ in Thousands	Dec. 15, 2015USD ($)	Oct. 01, 2015USD ($)	Sep. 18, 2015USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Mortgage Notes Payable [Line Items]
Mortgage notes payable				$ 3,438,714	$ 4,309,484
Final maturity date of mortgage notes				Apr. 10, 2022
Repayments of mortgage notes payable				$ 54,801	87,758	$ 80,311
Investment in Marketable Securities Related to Defeasance				667,335	0	0
Mortgage note payable legally defeased				640,500	0	0
Gains (losses) from early extinguishments of debt				$ (22,040)	$ (10,633)	122
Number Of Mortgage Loans Accounted For Fair Value				2	4
Outstanding balance of mortgage loans accounted for at fair value				$ 1,500,000	$ 2,200,000
Interest Expense Decrease Due To Recording Mortgage Loans At Fair Value				55,000	52,500	34,400
Cumulative Liability Related to the Fair Value of Debt Adjustment				80,200	138,700
Financing costs				61,402	69,127
Unamortized balance of historical fair value adjustments				80,235
Interest expense				$ 432,196	$ 455,743	$ 446,880
Minimum [Member]
Mortgage Notes Payable [Line Items]
Number Real Estate Assets Used For Mortgage Loan Collateral				1	1
Fixed Rate Mortgages [Member]
Mortgage Notes Payable [Line Items]
Mortgage notes payable				$ 3,400,000	$ 4,300,000
Contractual interest rate range, minimum				4.75%	4.75%
Contractual interest rate range, maximum				7.69%	7.69%
Contractual interest rate, weighted average interest rate				5.69%	5.70%
Variable Rate Mortgages [Member]
Mortgage Notes Payable [Line Items]
Number of variable rate mortgage loans				0	0
London Interbank Offered Rate				0.43%	0.17%
Secured Debt [Member] | Kingstowne Two and Kingstowne Retail [Member]
Mortgage Notes Payable [Line Items]
Repayments of mortgage notes payable		$ 29,800
Interest at a fixed rate		5.99%
Secured Debt [Member] | Two Hundred Clarendon Street and Garage [Member]
Mortgage Notes Payable [Line Items]
Interest at a fixed rate	5.68%
Investment in Marketable Securities Related to Defeasance	$ 667,300
Mortgage note payable legally defeased	640,500
Gains (losses) from early extinguishments of debt	(22,000)
Consolidated Properties [Member] | 505 9th Street [Member]
Mortgage Notes Payable [Line Items]
Ownership Percentage by Parent			50.00%
Mortgage Loan Related to Property Sales			$ 117,000
Consolidated Properties [Member] | Secured Debt [Member] | 505 9th Street [Member]
Mortgage Notes Payable [Line Items]
Ownership Percentage by Parent			50.00%
Mortgage Loan Related to Property Sales			$ 117,000
Interest at a fixed rate			5.73%
Mortgages [Member] | Secured Debt [Member] | Two Hundred Clarendon Street and Garage [Member]
Mortgage Notes Payable [Line Items]
Difference between US Treasuries and outstanding principal balance	26,800
Financing costs	1,400
Unamortized balance of historical fair value adjustments	4,800
Interest expense	$ 1,400

Derivative and Hedging Instru67

Derivative and Hedging Instruments (Details)	12 Months Ended
	Dec. 31, 2015USD ($)yrswaps	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ (141,000)
Fair Value	(10,302,000)	$ 0	$ 0
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount	950,000,000
Derivative, Net Liability Position, Aggregate Fair Value	11,700,000
Assets Needed for Immediate Settlement, Aggregate Fair Value	11,700,000
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion	12,700,000
Derivative Instruments, Gain Recognized in Other Comprehensive Income (Loss), Effective Portion	2,400,000
Fair Value	$ (10,302,000)
Boston Properties Limited Partnership [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Number of interest rate swap agreements entered into | swaps	17
Term of anticipated mortgage loan (in years) | yr	10
Derivative, Average Fixed Interest Rate	2.423%
Derivative, Notional Amount	$ 550,000,000
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) | yr	10
Fair Value	$ (4,231,000)
767 Fifth Partners LLC [Member]
Derivative [Line Items]
Ownership Percentage by Parent	60.00%
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Number of interest rate swap agreements entered into | swaps	14
Term of anticipated mortgage loan (in years) | yr	10
Derivative, Average Fixed Interest Rate	2.646%
Derivative, Notional Amount	$ 400,000,000
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) | yr	10
Fair Value	$ (6,071,000)
Boston Properties Limited Partnership [Member]
Derivative [Line Items]
Fair Value	$ (10,302,000)	$ 0	$ 0

Derivative and Hedging Instru68

Derivative and Hedging Instruments Derivative Instrument and Hedging Activities Notional Table (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fair Value	$ (10,302)	$ 0	$ 0
Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	950,000
Fair Value	(10,302)
Boston Properties Limited Partnership [Member] | Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	550,000
Fair Value	(4,231)
Boston Properties Limited Partnership [Member] | Interest Rate Swap [Member] | Interest Rate Swap Range 2.348% - 2.571% [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Liability, Notional Amount	$ 400,000
Derivative, Lower Fixed Interest Rate Range	2.348%
Derivative, Higher Fixed Interest Rate Range	2.571%
Fair Value	$ (5,419)
Boston Properties Limited Partnership [Member] | Interest Rate Swap [Member] | Interest Rate Swap Range 2.129% - 2.325% [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Notional Amount	$ 150,000
Derivative, Lower Fixed Interest Rate Range	2.129%
Derivative, Higher Fixed Interest Rate Range	2.325%
Fair Value	$ 1,188
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	400,000
Fair Value	(6,071)
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] | Interest Rate Swap Range 2.677% - 2.950% [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Liability, Notional Amount	$ 250,000
Derivative, Lower Fixed Interest Rate Range	2.677%
Derivative, Higher Fixed Interest Rate Range	2.95%
Fair Value	$ (7,247)
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] | Interest Rate Swap Range 2.336% - 2.430% [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Notional Amount	$ 150,000
Derivative, Lower Fixed Interest Rate Range	2.336%
Derivative, Higher Fixed Interest Rate Range	2.43%
Fair Value	$ 1,176

Derivative and Hedging Instru69

Derivative and Hedging Instruments Derivative Instruments and Hedging Activities Gain or Loss Recognized Related to Cash Flow Hedges (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Amount of loss related to the effective portion recognized in other comprehensive loss		$ (10,302)	$ 0	$ 0
Amount of loss related to the effective portion subsequently reclassified to earnings (1)	[1]	(2,510)	(2,508)	(2,513)
Amount of gain (loss) related to the ineffective portion and amount excluded from effectiveness testing		$ 0	$ 0	$ 0
[1]	Consists of amounts from interest rate hedging programs entered into prior to 2015.

Derivative and Hedging Instru70

Derivative and Hedging Instruments Derivative Instruments and Hedging Activities Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Beginning Balance		$ (9,304)	$ (11,556)	$ (13,817)
Amortization of interest rate contracts	[1],[2]	2,510	2,508	2,513
Effective portion of interest rate contracts		(10,302)	0	0
Other comprehensive (income) loss attributable to noncontrolling interests		2,982	(256)	(252)
Ending Balance		(14,114)	(9,304)	(11,556)
Boston Properties Limited Partnership [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Beginning Balance		(12,973)	(15,481)	(17,994)
Amortization of interest rate contracts	[2],[3]	2,510	2,508	2,513
Effective portion of interest rate contracts		(10,302)	0	0
Other comprehensive loss attributable to noncontrolling interests		2,428
Ending Balance		$ (18,337)	$ (12,973)	$ (15,481)
[1]	Amounts reclassified from comprehensive income primarily to interest expense within Boston Properties, Inc.’s Consolidated Statements of Operations
[2]	Consists of amounts from interest rate hedging programs entered into prior to 2015.
[3]	Amounts reclassified from comprehensive income primarily to interest expense within Boston Properties Limited Partnership's Consolidated Statements of Operations.

Unsecured Senior Notes Schedule

Unsecured Senior Notes Schedule of Unsecured Senior Notes (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Net unamortized discount		$ (10,683)	$ (12,296)
Total		5,289,317	5,287,704
Boston Properties Limited Partnership [Member]
Debt Instrument [Line Items]
Net unamortized discount		(10,683)	(12,296)
Total		5,289,317	$ 5,287,704
Boston Properties Limited Partnership [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Principal Amount		5,300,000
Net unamortized discount		(10,683)
Total		$ 5,289,317
Boston Properties Limited Partnership [Member] | Senior Notes [Member] | Unsecured Senior Notes 5.967%
Debt Instrument [Line Items]
Coupon/Stated Rate		5.875%
Effective Rate	[1]	5.967%
Principal Amount		$ 700,000
Maturity date	[2]	Oct. 15, 2019
Boston Properties Limited Partnership [Member] | Senior Notes [Member] | Unsecured Senior Notes 5.708%
Debt Instrument [Line Items]
Coupon/Stated Rate		5.625%
Effective Rate	[1]	5.708%
Principal Amount		$ 700,000
Maturity date	[2]	Nov. 15, 2020
Boston Properties Limited Partnership [Member] | Senior Notes [Member] | Unsecured Senior Notes 4.289%
Debt Instrument [Line Items]
Coupon/Stated Rate		4.125%
Effective Rate	[1]	4.289%
Principal Amount		$ 850,000
Maturity date	[2]	May 15, 2021
Boston Properties Limited Partnership [Member] | Senior Notes [Member] | Unsecured Senior Notes 3.853%
Debt Instrument [Line Items]
Coupon/Stated Rate		3.70%
Effective Rate	[1]	3.853%
Principal Amount		$ 850,000
Maturity date	[2]	Nov. 15, 2018
Boston Properties Limited Partnership [Member] | Senior Notes [Member] | Unsecured Senior Notes 3.954%
Debt Instrument [Line Items]
Coupon/Stated Rate		3.85%
Effective Rate	[1]	3.954%
Principal Amount		$ 1,000,000
Maturity date	[2]	Feb. 1, 2023
Boston Properties Limited Partnership [Member] | Senior Notes [Member] | Unsecured Senior Notes 3.279%
Debt Instrument [Line Items]
Coupon/Stated Rate		3.125%
Effective Rate	[1]	3.279%
Principal Amount		$ 500,000
Maturity date	[2]	Sep. 1, 2023
Boston Properties Limited Partnership [Member] | Senior Notes [Member] | Unsecured Senior Notes 3.916%
Debt Instrument [Line Items]
Coupon/Stated Rate		3.80%
Effective Rate	[1]	3.916%
Principal Amount		$ 700,000
Maturity date	[2]	Feb. 1, 2024
[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 Unsecure

Unsecured Senior Notes Unsecured Senior Notes (Narrative) (Details)	12 Months Ended
	Dec. 31, 2015
Debt Instrument [Line Items]
Maximum Secured Debt Leverage Ratio	55.00%
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%

Unsecured Line of Credit (Detai

Unsecured Line of Credit (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)yrmo	Dec. 31, 2014USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,000,000
Line of Credit Facility, Expiration Date	Jul. 26, 2018
Line of Credit Facility, Frequency of Commitment Fee Payment	quarterly
Line of Credit Facility, Amount Outstanding	$ 0	$ 0
Leverage Ratio, Maximum	60.00%
Leverage Ratio Maximum Increasing Limit	65.00%
Leverage Ratio Reduction Limit	60.00%
Leverage Ratio Reduction Period, Years | yr	1
Maximum Secured Debt Leverage Ratio	55.00%
Fixed Charge Coverage Ratio Minimum.	1.40
Maximum Unsecured Debt Leverage Ratio	60.00%
Unsecured Debt Leverage Ratio Maximum Increasing Limit	65.00%
Unsecured Debt Leverage Ratio Reduction Limit	60.00%
Unsecured Debt Leverage Ratio Reduction Period, Years | yr	1
Unsecured Debt Interest Coverage Ratio Minimum.	1.75
Alternative Base Interest Rate Calculation [Member]
Line of Credit Facility [Line Items]
Amount added to Federal Funds Rate to Calculate Interest Rate	0.50%
LIBOR Period Used to Calculate Interest Rate (in months) | mo	1
Amount added to LIBOR to Calculate Interest Rate	1.00%
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,500,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.35%
Maximum [Member] | Interest Rate Based on LIBOR or CDOR [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	1.70%
Maximum [Member] | Alternative Base Interest Rate Calculation [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	0.70%
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.125%
Minimum [Member] | Interest Rate Based on LIBOR or CDOR [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	0.925%
Minimum [Member] | Alternative Base Interest Rate Calculation [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	0.00%
Rate Based on Current Credit Rating [Member]
Line of Credit Facility [Line Items]
Line Of Credit Facility Extension Fee	0.15%
Rate Based on Current Credit Rating [Member] | Interest Rate Based on LIBOR or CDOR [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	1.00%
Rate Based on Current Credit Rating [Member] | Alternative Base Interest Rate Calculation [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate	0.00%

Commitments And Contingencies (

Commitments And Contingencies (Details) - USD ($) $ in Millions	2 Months Ended	10 Months Ended	12 Months Ended
	Feb. 28, 2015	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2009	Sep. 09, 2015	Mar. 11, 2015	Sep. 18, 2014	Jan. 10, 2014
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations		$ 22.8	$ 22.8
Property insurance program per occurrence limits		1,000	1,000
Per occurrence limit for NBCR Coverage			1,000
Value of program trigger		100	$ 100
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	170
Annual aggregate limit of the earthquake insurance which covers San Francisco region	$ 120	170
Amount of earthquake insurance provided by IXP, LLC as direct insurer San Francisco			$ 20
Earthquake Coverage Included In Builders Risk Policy For Below Grade improvements for Transbay Tower			60
Operating partnership guarantee to cover liabilities of IXP		20	20
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Property insurance program per occurrence limits		1,625	1,625
Fountain Square
Commitments And Contingencies [Line Items]
Guarantee Obligation Related To Tenant Re-Leasing Costs			0.7
601 Lexington Avenue
Commitments And Contingencies [Line Items]
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP			250
Lehman [Member]
Commitments And Contingencies [Line Items]
Bankruptcy claim, amount filed by general creditor				$ 45.3
Bankruptcy claim amount allowed by court to creditor		$ 29.4	$ 29.4					$ 45.2
Bankruptcy Claims, Amount of Claims Settled					$ 3.6	$ 4.5	$ 7.7

Noncontrolling Interests (Narra

Noncontrolling Interests (Narrative) (Details)	Dec. 31, 2015shares
Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Operating Partnership (OP) Units (in shares)	16,097,473
Long-Term Incentive Plan (LTIP) Units (in shares)	1,831,714
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Long-Term Incentive Plan (LTIP) Units (in shares)	216,854
MYLTIP 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	309,818
MYLTIP 2014[Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	476,320
MYLTIP 2015 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	368,415

Noncontrolling Interests (Redee

Noncontrolling Interests (Redeemable Preferred Units) (Narrative) (Details) $ / shares in Units, $ in Millions	Jun. 25, 2015USD ($)$ / sharesshares	May. 12, 2014$ / sharesshares	Dec. 31, 2014shares	Dec. 31, 2013shares	May. 15, 2015$ / shares	Feb. 17, 2015$ / shares	Nov. 05, 2014USD ($)	Oct. 16, 2014shares	Jul. 03, 2014USD ($)	May. 19, 2014shares	Aug. 29, 2013dshares
Series Two Preferred Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Units converted (in shares)			666,116	329,881
Series Two Preferred Units [Member] | Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Liquidation preference percentage		6.00%
Operating Units liquidation preference (in dollars per share) | $ / shares		$ 38.10
OP Units for each Preferred Unit (in shares)		1.312336
Units converted (in shares)		666,116		329,881
Series Two Preferred Units On Converted Basis		874,168		432,914
Preferred Units Liquidation Preference | $ / shares		$ 50
Series Four Preferred Units [Member] | Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Series Four Preferred Units Redeemed	12,667										861,400
Series Four Preferred Units Released from Escrow								27,773		319,687
Redemption of Series Four Preferred Units | $	$ 0.6						$ 1.4		$ 16
Distributions to Series Two and Four Preferred Units (in dollars per share) | $ / shares					$ 0.25	$ 0.25
Series Four Preferred Units Annual Dividend Payable Rate	2.00%
Preferred Units Liquidation Preference | $ / shares	$ 50
First opportunity to redeem Series Four Preferred Units (in days) | d											30
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Units converted (in shares)			874,168	432,914

Noncontrolling Interests (Red77

Noncontrolling Interests (Redeemable Preferred Units) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning Balance	$ 633
Net income	6	$ 1,023	$ 6,046
Redemption of redeemable preferred units (Series Four Preferred Units)	(633)	(17,373)	(43,070)
Conversion of redeemable preferred units (Series Two Preferred Units) to common units		33,306	16,494
Ending Balance	0	633
Redeemable Preferred Units [Member]
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning Balance	633	51,312	110,876
Net income	6	1,023	6,046
Distributions	(6)	(1,023)	(6,046)
Redemption of redeemable preferred units (Series Four Preferred Units)	(633)	(17,373)	(43,070)
Conversion of redeemable preferred units (Series Two Preferred Units) to common units		(33,306)	(16,494)
Ending Balance	$ 0	$ 633	$ 51,312

Noncontrolling Interests Redeem

Noncontrolling Interests Redeemable interest in property partnerships (narrative) (Details) - USD ($) $ in Thousands	Sep. 15, 2015	Aug. 06, 2015	Oct. 04, 2012	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Payments for Repurchase of Redeemable Noncontrolling Interest				$ 108,499	$ 0	$ 0
Fountain Square
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Aggregate purchase price			$ 385,000
Debt recorded upon consolidation			$ 211,300
Ownership Percentage	50.00%	50.00%	50.00%
Fixed Price to Acquire Remaining Portion of Joint venture		$ 100,900
Consideration paid			$ 87,000
Ownership Percentage by Parent			50.00%
Future Fixed Price to Acquire Remaining Portion of Joint venture			$ 102,000
Payments for Repurchase of Redeemable Noncontrolling Interest	$ 100,900
Mortgage debt assumed upon acquisition of noncontrolling interest	$ 105,600

Noncontrolling Interests Rede79

Noncontrolling Interests Redeemable Property Partnerships (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning Balance	$ 104,692	$ 99,609	$ 97,558
Net Loss	(7)	(603)	(1,839)
Distributions	(2,900)	(6,000)	(4,585)
Adjustment to reflect redeemable partnership units at redemption value	5,128	11,686	8,475
Acquisition of interest	(106,913)
Ending Balance	$ 0	$ 104,692	$ 99,609

(Common Units) (Narrative) (Det

(Common Units) (Narrative) (Details) $ / shares in Units, $ in Millions	Oct. 30, 2015$ / shares	Jul. 31, 2015$ / shares	Apr. 30, 2015$ / shares	Feb. 06, 2015USD ($)shares	Jan. 28, 2015$ / shares	Dec. 31, 2015USD ($)yr$ / sharesshares	Dec. 31, 2014USD ($)shares	Dec. 17, 2015$ / shares
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distributions Declared To OP And LTIP Units Per Unit								$ 0.65
Distributions Declared To OPP and MYLTIP Units Per Unit								0.065
OP Units for redemption (in shares) | shares						424,236	80,246
Redemption of OP units issued on conversion of Series Two Preferred Units (in shares) | shares						0	3,734
Redemption of OP units issued on conversion of LTIP Units (in shares) | shares						65,192	67,857
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)	$ 0.65	$ 0.65	$ 0.65		$ 0.65
Distribution paid to outperformance awards, OPP Units and MYLTIP Units (in dollars per share)	$ 0.065	$ 0.065	0.065		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 | $						$ 2,300
Closing price of common stock (in dollars per share)						$ 127.54
OPP Units 2011 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Accelerated Compensation Expenses Related To 2011 OPP Units | $							$ 1.2
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distributions made to OP and LTIP units per unit (in dollars per share)			$ 0.416
special dividend [Member] | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distributions Declared To OP And LTIP Units Per Unit								$ 1.25
Distributions made to OP and LTIP units per unit (in dollars per share)					$ 4.50
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards earned | $				$ 32.1
Potential maximum amount of Outperformance Awards earned (percent)				80.00%
Potential Awards Earned | $				$ 40
2012 OPP Units forfeited | shares				174,549

Noncontrolling Interests (Prope

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) $ in Thousands	Sep. 18, 2015USD ($)ft²	Oct. 30, 2014USD ($)ft²floor	May. 31, 2013USD ($)ft²partners	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 10, 2015USD ($)	Oct. 09, 2013USD ($)ft²
Noncontrolling Interest [Line Items]
Property partnerships				$ 1,574,400	$ 1,602,467
Noncontrolling interest in property partnerships recorded upon consolidation				0	0	$ 480,861
Proceeds from sales of real estate				602,600	419,864	250,078
Gains on sales of real estate				$ 375,895	$ 168,039	$ 0
505 9th Street [Member] | Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Ownership Percentage by Parent	50.00%
Sale Price Of Sold Property	$ 318,000
Mortgage Loan Related to Property Sales	$ 117,000
Net Rentable Area | ft²	322,000
Proceeds from sales of real estate	$ 194,600
Gains on sales of real estate	199,500
Noncontroling interest for a dissolved entity relcassed to accounts payable and and accrued expenses							$ 4,100
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member] | 505 9th Street [Member] | Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Proceeds from sales of real estate	97,300
Gains on sales of real estate	$ 101,100
767 Fifth Avenue (the General Motors Building)
Noncontrolling Interest [Line Items]
Number of Joint Venture Partners | partners			2
Ownership Percentage			40.00%
Noncontrolling interest in property partnerships recorded upon consolidation			$ 480,861
Net Rentable Area | ft²			1,800,000
Time Square Tower [Member]
Noncontrolling Interest [Line Items]
Sale Price Of Sold Property								$ 684,000
Portion allocation to noncontrolling interest based on carrying value of the total equity of the property prior to the sale								243,500
Difference between net cash proceeds received and noncontrolling interest recognized								429,600
Proceeds from sale of an interest in a real estate asset								$ 673,100
Ownership Percentage								45.00%
Net Rentable Area | ft²								1,246,000
601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member]
Noncontrolling Interest [Line Items]
Sale Price Of Sold Property		$ 1,827,000
Portion allocation to noncontrolling interest based on carrying value of the total equity of the property prior to the sale		849,000
Difference between net cash proceeds received and noncontrolling interest recognized		648,400
Proceeds from sale of an interest in a real estate asset		$ 1,497,000
Ownership Percentage		45.00%
Disposa Group Including Discontinued Operations Secured Debt		$ 712,900
601 Lexington Avenue | 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member]
Noncontrolling Interest [Line Items]
Net Rentable Area | ft²		1,669,000
Atlantic Wharf | 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member]
Noncontrolling Interest [Line Items]
Net Rentable Area | ft²		791,000
100 Federal Street | 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member]
Noncontrolling Interest [Line Items]
Net Rentable Area | ft²		1,323,000
Office Tower [Member] | 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member]
Noncontrolling Interest [Line Items]
Number of floors in building | floor		59
Low Rise Building [Member] | 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street [Member]
Noncontrolling Interest [Line Items]
Number of floors in building | floor		6

Noncontrolling Interests Rede82

Noncontrolling Interests Redeemable preferred units of Boston Properties Limited Partnership (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Noncontrolling Interest [Line Items]
Beginning Balance		$ 633
Net income		6	$ 1,023	$ 6,046
Redemption of redeemable preferred units (Series Four Preferred Units)		(633)	(17,373)	(43,070)
Reallocation of partnership interest (1)		0	0	0
Ending Balance		0	633
Boston Properties Limited Partnership [Member]
Noncontrolling Interest [Line Items]
Net income		6	1,023	6,046
Redemption of redeemable preferred units (Series Four Preferred Units)		(633)	(17,373)	(43,070)
Reallocation of partnership interest (1)		(14,343)	$ (2,700)	$ (30,291)
Series Two Preferred Units [Member]
Noncontrolling Interest [Line Items]
Units converted (in shares)			666,116	329,881
OP Units [Member]
Noncontrolling Interest [Line Items]
Units converted (in shares)			874,168	432,914
Redeemable Preferred Units [Member] | Boston Properties Limited Partnership [Member]
Noncontrolling Interest [Line Items]
Beginning Balance		633	$ 105,746	$ 199,378
Net income		6	1,023	6,046
Distributions		(6)	(1,023)	(6,046)
Redemption of redeemable preferred units (Series Four Preferred Units)		(633)	(17,373)	(43,070)
Reallocation of partnership interest (1)	[1]		(87,740)	(50,562)
Ending Balance		$ 0	$ 633	$ 105,746
[1]	Includes the conversion of 666,116 and 329,881 Series Two Preferred Units into 874,168 and 432,914 OP Units during the years ended December 31, 2014 and 2013, respectively.

Noncontrolling Interests Rede83

Noncontrolling Interests Redeemable common units of Boston Properties Limited Partnership (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Noncontrolling Interest [Line Items]
Conversion of redeemable partnership units	$ 0	$ 0	$ 0
Adjustment to reflect redeemable partnership units at redemption value	5,128	11,686	8,475
Boston Properties Limited Partnership [Member]
Noncontrolling Interest [Line Items]
Beginning Balance	2,310,046	1,710,218	1,836,522
Contributions	39,030	23,990	26,398
Net income	66,951	50,862	84,236
Distributions	(69,447)	(126,948)	(83,448)
Conversion of redeemable partnership units	(14,343)	(2,700)	(30,291)
Unearned compensation	(4,579)	(2,813)	1,472
Other comprehensive income (loss)	(554)	256	252
Adjustment to reflect redeemable partnership units at redemption value	(40,415)	657,181	(124,923)
Ending Balance	$ 2,286,689	$ 2,310,046	$ 1,710,218

Noncontrolling Interests noncon

Noncontrolling Interests noncontrolling interests—property partnerships table (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Noncontrolling Interest [Line Items]
Beginning Balance	$ 1,602,467
Capital contributions	2,705
Dissolution	(4,082)
Net income (loss)	149,855	$ 30,561	$ 1,347
Accumulated other comprehensive loss	(2,982)	256	252
Ending Balance	1,574,400	1,602,467
Property Partnerships Member
Noncontrolling Interest [Line Items]
Beginning Balance	1,602,467	726,132	(1,964)
Fair value of capital recorded upon consolidation			480,861
Capital contributions	3,758	887,975	257,564
Dissolution	(4,082)
Net income (loss)	144,734	19,478	(5,290)
Accumulated other comprehensive loss	(2,428)
Distributions	(170,049)	(31,118)	(5,039)
Ending Balance	$ 1,574,400	$ 1,602,467	$ 726,132

Stockholders' Equity _ Partne85

Stockholders' Equity / Partners' Capital (Details)	12 Months Ended
	Dec. 31, 2015USD ($)yr$ / sharesshares	Dec. 31, 2014$ / sharesshares	Dec. 31, 2013shares	Mar. 27, 2018$ / shares
Class of Stock [Line Items]
General Partners' Capital Account, Units Outstanding (in units)	1,715,092
Limited Partners' Capital Account, Units Outstanding	151,864,874
Common stock, shares outstanding	153,579,966	153,113,945
Shares of Common Stock upon the exercise of options to purchase Common Stock by certain employees	11,447	21,459
Shares of its Common Stock in connection with the redemption of an equal number of OP Units	424,236	80,246
Atm Program [Member]
Class of Stock [Line Items]
At the market stock offering program, aggregate value of common stock | $	$ 600,000,000
At Market Stock Offering Program Maximum Length Of Program In Years | yr	3
ATM program amount issued | $	$ 0
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	80,000	80,000
Preferred Stock, Dividend Rate, Percentage	5.25%
Series B Liquidation Preference Per Share | $ / shares	$ 2,500	$ 2,500		$ 2,500
Depositary shares of Series B Cumulative Redeemable Preferred [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	8,000,000
Series B Liquidation Preference Per Share | $ / shares	$ 25			$ 25
Boston Properties Limited Partnership [Member]
Class of Stock [Line Items]
General Partners' Capital Account, Units Outstanding (in units)	1,715,092	1,710,644
Limited Partners' Capital Account, Units Outstanding	151,864,874	151,403,301
Shares of its Common Stock in connection with the redemption of an equal number of OP Units	424,236	80,246	929,441

Stockholders' Equity _ Partne86

Stockholders' Equity / Partners' Capital Dividends / distributions (Details) - $ / shares

Nov. 16, 2015

Oct. 30, 2015

Aug. 17, 2015

Jul. 31, 2015

May. 15, 2015

Apr. 30, 2015

Feb. 17, 2015

Jan. 28, 2015

Feb. 16, 2016

Jan. 28, 2016

Dividends / Distributions [Line Items]

Special dividend / distribution (per share / common unit amount)

$ 4.50

$ 1.25

Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid

$ 0.65

$ 0.65

$ 0.65

5.15

[1]

Dividends Payable, Amount Per Share / Unit

[2]

1.90

Boston Properties Limited Partnership [Member]

Dividends / Distributions [Line Items]

Special dividend / distribution (per share / common unit amount)

4.50

1.25

Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid

$ 0.65

$ 0.65

$ 0.65

$ 5.15

[1]

Dividends Payable, Amount Per Share / Unit

[2]

$ 1.90

Series B Cumulative Redeemable Preferred Stock / Unit [Member]

Dividends / Distributions [Line Items]

Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid

$ 32.8125

$ 32.8125

$ 32.8125

$ 32.8125

Dividends Payable, Amount Per Share / Unit

$ 32.8125

[1]

Includes a special dividend/distribution of $4.50 per share/common unit.

[2]

Includes a special dividend/distribution of $1.25 per share/common unit.

Stockholders' Equity _ Partne87

Stockholders' Equity / Partners' Capital Partners' Capital Changes in Issued and Outstanding Partners' Capital Units (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Limited Partners' Capital Account [Line Items]
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	424,236	80,246
Limited Partners' Ending Balance	151,864,874
General Partners' Ending Balance	1,715,092
Boston Properties Limited Partnership [Member]
Limited Partners' Capital Account [Line Items]
General Partners' Beginning Balance	1,710,644
Limited Partners Beginning Balance	151,403,301
Partners' Capital Beginning Balance	153,113,945	152,983,101	151,601,209
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	6,199	6,964	6,442
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	35,586	43,634	26,893
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	424,236	80,246	929,441
Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs			419,116
Limited Partners' Ending Balance	151,864,874	151,403,301
Partners' Capital Ending Balance	153,579,966	153,113,945	152,983,101
General Partners' Ending Balance	1,715,092	1,710,644
Boston Properties Limited Partnership [Member] | General Partner [Member]
Limited Partners' Capital Account [Line Items]
General Partners' Beginning Balance	1,710,644	1,700,222	1,689,580
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	59	555	50
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	340	3,476	207
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	4,049	6,391	7,158
Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs			3,227
General Partners' Ending Balance	1,715,092	1,710,644	1,700,222
Boston Properties Limited Partnership [Member] | Limited Partner [Member]
Limited Partners' Capital Account [Line Items]
Limited Partners Beginning Balance	151,403,301	151,282,879	149,911,629
Units issued to Boston Properties, Inc. related to Common Stock issued under the Employee Stock Purchase Plan	6,140	6,409	6,392
Units issued to Boston Properties, Inc. related to Common Stock issued under the Stock Option and Incentive Plan, net	35,246	40,158	26,686
Units issued to Boston Properties, Inc. related to Common Stock issued in exchange for OP Units	420,187	73,855	922,283
Units issued to Boston Properties, Inc. related to Common Stock issued under the “at the market” (ATM) stock offering programs			415,889
Limited Partners' Ending Balance	151,864,874	151,403,301	151,282,879

Stockholders' Equity _ Partne88

Stockholders' Equity / Partners' Capital Partners' Capital Change in Series B Preferred Units (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Entity Information [Line Items]
Beginning Balance	$ 200,000
Ending Balance	200,000	$ 200,000
Boston Properties Limited Partnership [Member]
Entity Information [Line Items]
Beginning Balance	193,623	193,623	$ 0
Issuance of Series B Preferred Units			193,623
Net Income	10,500	10,500	8,057
Distributions	(10,500)	(10,500)	(8,057)
Ending Balance	$ 193,623	$ 193,623	$ 193,623

Future Minimum Rents Narrative

Future Minimum Rents Narrative (Details) - tenants	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Future Minimum Rent [Line Items]
Number Of Tenants Above Concentration Amount.	0	0	0
Concentration Risk, Percentage	10.00%	10.00%	10.00%
Minimum [Member]
Future Minimum Rent [Line Items]
Initial Term Lease Expiration Date	2,016
Maximum [Member]
Future Minimum Rent [Line Items]
Initial Term Lease Expiration Date	2,046

Future Minimum Rents Future min

Future Minimum Rents Future minimum rent under non-cancelable operating leases (Details) $ in Thousands	Dec. 31, 2015USD ($)
Future minimum rent [Abstract]
2,016	$ 1,854,538
2,017	1,815,632
2,018	1,733,703
2,019	1,666,019
2,020	1,500,843
Thereafter	$ 8,667,163

Segment Information (Schedule O

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 2,345,175	$ 2,240,119	$ 1,987,671
Rental Revenue: Office/Technical	58,163	61,985	55,525
Rental Revenue: Residential	18,883	26,193	22,318
Rental Revenue: Hotel	46,046	43,385	40,330
Rental Revenue Total	$ 2,468,267	$ 2,371,682	$ 2,105,844
Rental Revenue: % of Grand Totals	100.00%	100.00%	100.00%
Rental Expenses: Class A Office	$ 848,763	$ 802,902	$ 716,049
Rental Expenses: Office/Technical	15,262	16,466	14,777
Rental Expenses: Residential	8,227	15,922	12,130
Rental Expenses: Hotel	32,084	29,236	28,447
Rental Expenses: Total	$ 904,336	$ 864,526	$ 771,403
Rental Expenses: % Of Grand Totals	100.00%	100.00%	100.00%
Net operating Income	$ 1,563,931	$ 1,507,156	$ 1,334,441
Net operating Income: % of Grand Totals	100.00%	100.00%	100.00%
Boston [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 692,419	$ 692,116	$ 665,991
Rental Revenue: Office/Technical	23,827	23,801	22,617
Rental Revenue: Residential	4,801	4,528	4,395
Rental Revenue: Hotel	46,046	43,385	40,330
Rental Revenue Total	$ 767,093	$ 763,830	$ 733,333
Rental Revenue: % of Grand Totals	31.08%	32.21%	34.82%
Rental Expenses: Class A Office	$ 280,307	$ 270,947	$ 259,997
Rental Expenses: Office/Technical	7,034	7,173	6,879
Rental Expenses: Residential	2,006	1,957	1,823
Rental Expenses: Hotel	32,084	29,236	28,447
Rental Expenses: Total	$ 321,431	$ 309,313	$ 297,146
Rental Expenses: % Of Grand Totals	35.54%	35.78%	38.52%
Net operating Income	$ 445,662	$ 454,517	$ 436,187
Net operating Income: % of Grand Totals	28.50%	30.16%	32.69%
New York [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 1,000,030	$ 928,692	$ 725,566
Rental Revenue: Office/Technical	0	0	0
Rental Revenue: Residential	0	0	0
Rental Revenue: Hotel	0	0	0
Rental Revenue Total	$ 1,000,030	$ 928,692	$ 725,566
Rental Revenue: % of Grand Totals	40.52%	39.16%	34.46%
Rental Expenses: Class A Office	$ 346,897	$ 315,330	$ 251,640
Rental Expenses: Office/Technical	0	0	0
Rental Expenses: Residential	0	0	0
Rental Expenses: Hotel	0	0	0
Rental Expenses: Total	$ 346,897	$ 315,330	$ 251,640
Rental Expenses: % Of Grand Totals	38.36%	36.47%	32.62%
Net operating Income	$ 653,133	$ 613,362	$ 473,926
Net operating Income: % of Grand Totals	41.76%	40.70%	35.51%
San Francisco [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 280,005	$ 237,381	$ 214,755
Rental Revenue: Office/Technical	22,429	23,840	17,259
Rental Revenue: Residential	0	0	0
Rental Revenue: Hotel	0	0	0
Rental Revenue Total	$ 302,434	$ 261,221	$ 232,014
Rental Revenue: % of Grand Totals	12.25%	11.01%	11.02%
Rental Expenses: Class A Office	$ 94,268	$ 85,178	$ 77,905
Rental Expenses: Office/Technical	3,938	4,955	3,708
Rental Expenses: Residential	0	0	0
Rental Expenses: Hotel	0	0	0
Rental Expenses: Total	$ 98,206	$ 90,133	$ 81,613
Rental Expenses: % Of Grand Totals	10.86%	10.43%	10.58%
Net operating Income	$ 204,228	$ 171,088	$ 150,401
Net operating Income: % of Grand Totals	13.06%	11.35%	11.27%
Washington, DC [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 372,721	$ 381,930	$ 381,359
Rental Revenue: Office/Technical	11,907	14,344	15,649
Rental Revenue: Residential	14,082	21,665	17,923
Rental Revenue: Hotel	0	0	0
Rental Revenue Total	$ 398,710	$ 417,939	$ 414,931
Rental Revenue: % of Grand Totals	16.15%	17.62%	19.70%
Rental Expenses: Class A Office	$ 127,291	$ 131,447	$ 126,507
Rental Expenses: Office/Technical	4,290	4,338	4,190
Rental Expenses: Residential	6,221	13,965	10,307
Rental Expenses: Hotel	0	0	0
Rental Expenses: Total	$ 137,802	$ 149,750	$ 141,004
Rental Expenses: % Of Grand Totals	15.24%	17.32%	18.28%
Net operating Income	$ 260,908	$ 268,189	$ 273,927
Net operating Income: % of Grand Totals	16.68%	17.79%	20.53%

Segment Information (Schedule92

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Development and management services income	$ 22,554	$ 25,316	$ 29,695
Income from unconsolidated joint ventures	22,770	12,769	75,074
Gains on consolidation of joint ventures	0	0	385,991
Interest and other income	6,777	8,765	8,310
Gains (losses) from investments in securities	(653)	1,038	2,911
Gains (losses) from early extinguishments of debt	(22,040)	(10,633)	122
Income from discontinued operations	0	0	8,022
Gain on sale of real estate from discontinued operations	0	0	112,829
Gain on forgiveness of debt from discontinued operations	0	0	20,182
General and administrative expense	96,319	98,937	115,329
Transaction costs	1,259	3,140	1,744
Depreciation and amortization expense	639,542	628,573	560,637
Interest expense	432,196	455,743	446,880
Impairment loss	0	0	8,306
Impairment loss from discontinued operations	0	0	3,241
Noncontrolling interest in property partnerships	149,855	30,561	1,347
Noncontrolling interest - redeemable preferred units	6	1,023	6,046
Noncontrolling interest-common units of the Operating Partnership	66,951	50,862	70,085
Noncontrolling interest in discontinued operations-common units of the Operating Partnership	0	0	14,151
Preferred dividends / distributions	10,500	10,500	8,057
Net income attributable to the Company''s common shareholders / unitholders	572,606	433,111	741,754
Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Operating Income	1,563,931	1,507,156	1,334,441
Development and management services income	22,554	25,316	29,695
Income from unconsolidated joint ventures	22,770	12,769	75,074
Gains on consolidation of joint ventures	0	0	385,991
Interest and other income	6,777	8,765	8,310
Gains (losses) from investments in securities	(653)	1,038	2,911
Gains (losses) from early extinguishments of debt	(22,040)	(10,633)	122
Income from discontinued operations	0	0	8,022
Gain on sale of real estate from discontinued operations	0	0	112,829
Gain on forgiveness of debt from discontinued operations	0	0	20,182
Gains on sales of real estate	375,895	168,039	0
General and administrative expense	96,319	98,937	115,329
Transaction costs	1,259	3,140	1,744
Depreciation and amortization expense	639,542	628,573	560,637
Interest expense	432,196	455,743	446,880
Impairment loss	0	0	8,306
Impairment loss from discontinued operations	0	0	3,241
Noncontrolling interest in property partnerships	149,855	30,561	1,347
Noncontrolling interest - redeemable preferred units	6	1,023	6,046
Noncontrolling interest-common units of the Operating Partnership	66,951	50,862	70,085
Noncontrolling interest in discontinued operations-common units of the Operating Partnership	0	0	14,151
Preferred dividends / distributions	10,500	10,500	8,057
Net income attributable to the Company''s common shareholders / unitholders	572,606	433,111	741,754
Boston Properties Limited Partnership [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Development and management services income	22,554	25,316	29,695
Income from unconsolidated joint ventures	22,770	12,769	75,074
Gains on consolidation of joint ventures	0	0	385,991
Interest and other income	6,777	8,765	8,310
Gains (losses) from investments in securities	(653)	1,038	2,911
Gains (losses) from early extinguishments of debt	(22,040)	(10,633)	122
Income from discontinued operations	0	0	8,022
Gain on sale of real estate from discontinued operations	0	0	115,459
Gain on forgiveness of debt from discontinued operations	0	0	20,736
General and administrative expense	96,319	98,937	115,329
Transaction costs	1,259	3,140	1,744
Depreciation and amortization expense	631,549	620,064	552,589
Interest expense	432,196	455,743	446,880
Impairment loss	0	0	4,401
Impairment loss from discontinued operations	0	0	2,852
Noncontrolling interest in property partnerships	149,855	30,561	1,347
Noncontrolling interest - redeemable preferred units	6	1,023	6,046
Preferred dividends / distributions	10,500	10,500	8,057
Net income attributable to the Company''s common shareholders / unitholders	648,748	499,129	841,516
Boston Properties Limited Partnership [Member] | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Operating Income	1,563,931	1,507,156	1,334,441
Development and management services income	22,554	25,316	29,695
Income from unconsolidated joint ventures	22,770	12,769	75,074
Gains on consolidation of joint ventures	0	0	385,991
Interest and other income	6,777	8,765	8,310
Gains (losses) from investments in securities	(653)	1,038	2,911
Gains (losses) from early extinguishments of debt	(22,040)	(10,633)	122
Income from discontinued operations	0	0	8,022
Gain on sale of real estate from discontinued operations	0	0	115,459
Gain on forgiveness of debt from discontinued operations	0	0	20,736
Gains on sales of real estate	377,093	174,686	0
General and administrative expense	96,319	98,937	115,329
Transaction costs	1,259	3,140	1,744
Depreciation and amortization expense	631,549	620,064	552,589
Interest expense	432,196	455,743	446,880
Impairment loss	0	0	4,401
Impairment loss from discontinued operations	0	0	2,852
Noncontrolling interest in property partnerships	149,855	30,561	1,347
Noncontrolling interest - redeemable preferred units	6	1,023	6,046
Preferred dividends / distributions	10,500	10,500	8,057
Net income attributable to the Company''s common shareholders / unitholders	$ 648,748	$ 499,129	$ 841,516

Segment Information Segment rep

Segment Information Segment reporting (narrative) (Details)	May. 31, 2013partners
767 Fifth Avenue (the General Motors Building)
Segment Reporting Information [Line Items]
Number of Joint Venture Partners	2

Earnings Per Share _ Common U94

Earnings Per Share / Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Basic Earnings:
Income from continuing operations attributable to the Company (Numerator)									$ 572,606	$ 433,111	$ 618,113
Net income attributable to the Company in Shares / Units (Denominator)									153,471,000	153,089,000	152,201,000
Income from continuing operations attributable to the Company Per Share / Per Unit Amount (in dollars per share / unit)									$ 3.73	$ 2.83	$ 4.06
Discontinued operations attributable to the Company Income (Numerator)											$ 123,641
Discontinued Operations (in shares)											0
Discontinued operations attributable to the Company Per Share / Unit Amount (in dollars per share / unit)											$ 0.81
Net Income Loss Available To the Company's Common Stockholders / Unitholders											$ 741,594
Allocation of undistributed earnings to participating securities											$ (160)
Allocation of undistributed earnings to participating securities (in shares)											0
Allocation of undistributed earnings to participating securities (in shares)											$ 0
Net income attributable to the Company Per Share / Unit Amount (in dollars per share / unit)	$ 0.90	$ 1.20	$ 0.52	$ 1.12	$ 1.14	$ 0.83	$ 0.50	$ 0.35	$ 3.73	$ 2.83	$ 4.87
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes, Income (Numerator)									$ 0	$ 0	$ 0
Stock Based Compensation and Exchangeable Senior Notes, Shares / Units (Denominator)									373,000	219,000	320,000
Stock Based Compensation and Exchangeable Senior Notes Per Share / Unit Amount									$ (0.01)	$ 0	$ (0.01)
Diluted Earnings:
Diluted Earnings: Net income, Income (Numerator)									$ 572,606	$ 433,111	$ 741,594
Diluted Earnings: Net income, Shares / Units (Denominator)									153,844,000	153,308,000	152,521,000
Diluted Earnings: Net income, Per Share / Unit Amount (in dollars per share / unit)	0.90	1.20	0.52	1.11	1.14	0.83	0.50	0.35	$ 3.72	$ 2.83	$ 4.86
Boston Properties Limited Partnership [Member]
Redeemable Common Units									17,668,000	17,364,000	16,925,000
Basic Earnings:
Income from continuing operations attributable to the Company (Numerator)									$ 648,748	$ 499,129	$ 700,151
Net income attributable to the Company in Shares / Units (Denominator)									171,139,000	170,453,000	169,126,000
Income from continuing operations attributable to the Company Per Share / Per Unit Amount (in dollars per share / unit)									$ 3.79	$ 2.93	$ 4.14
Discontinued operations attributable to the Company Income (Numerator)											$ 141,365
Discontinued Operations (in shares)											0
Discontinued operations attributable to the Company Per Share / Unit Amount (in dollars per share / unit)											$ 0.84
Net Income Loss Available To the Company's Common Stockholders / Unitholders											$ 841,338
Allocation of undistributed earnings to participating securities											$ (178)
Allocation of undistributed earnings to participating securities (in shares)											0
Allocation of undistributed earnings to participating securities (in shares)											$ (0.01)
Net income attributable to the Company Per Share / Unit Amount (in dollars per share / unit)	0.92	1.21	0.53	1.13	1.20	0.85	0.51	0.37	$ 3.79	$ 2.93	$ 4.97
Effect of Dilutive Securities:
Stock Based Compensation and Exchangeable Senior Notes, Income (Numerator)									$ 0	$ 0	$ 0
Stock Based Compensation and Exchangeable Senior Notes, Shares / Units (Denominator)									373,000	219,000	320,000
Stock Based Compensation and Exchangeable Senior Notes Per Share / Unit Amount									$ (0.01)	$ (0.01)	$ 0
Diluted Earnings:
Diluted Earnings: Net income, Income (Numerator)									$ 648,748	$ 499,129	$ 841,338
Diluted Earnings: Net income, Shares / Units (Denominator)									171,512,000	170,672,000	169,446,000
Diluted Earnings: Net income, Per Share / Unit Amount (in dollars per share / unit)	$ 0.92	$ 1.21	$ 0.53	$ 1.12	$ 1.20	$ 0.85	$ 0.51	$ 0.37	$ 3.78	$ 2.92	$ 4.97

Employee Benefit Plans (Details

Employee Benefit Plans (Details)	12 Months Ended			180 Months Ended	192 Months Ended
	Dec. 31, 2015USD ($)mo	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)yrage	Dec. 31, 2015USD ($)
Employee Benefit Plans [Abstract]
Eligibility Period For 401K Savings Plan In Months | mo	3
Employer Matching Contribution, Percent of Match					200.00%
Employer Matching Contribution, Percent of Employees' Gross Pay					3.00%
Maximum Eligible Earnings As Established By IRS For Matching Contributions	$ 265,000	$ 260,000	$ 255,000
Employer Contribution Amount	3,700,000	3,500,000	3,400,000
Years Of Service For Supplemental Retirement Contribution | yr				10
Age Of Employee For Supplemental Retirement Contribution | age				40
Annual Supplemental Retirement Contribution And Credit Total.	42,000	52,000	$ 60,000
Separate Unrestricted Cash For Deferred Compensation Plan.	20,400,000	19,500,000		$ 20,400,000	$ 20,400,000
Deferred Compensation Liability	$ 20,400,000	$ 19,500,000		$ 20,400,000	$ 20,400,000

Stock Option and Incentive Pl96

Stock Option and Incentive Plan (Narrative) (Details)	Feb. 06, 2015USD ($)shares	Jan. 21, 2015USD ($)yrtiersindices	May. 15, 2012yrshares	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015shares	Apr. 02, 2013shares	Mar. 11, 2013USD ($)
OPP Units 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned	$ 40,000,000
Outperformance awards earned	$ 32,100,000
Potential maximum amount of Outperformance Awards earned (percent)	80.00%
2012 OPP Units forfeited | shares	174,549
2012 Stock Option and Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Additional Shares Authorized | shares			13,000,000
Other Than Stock Options Awards Conversion Ratio			2.32
Stock Option Awards Conversion Ratio			1
Stock Option and Incentive Plan Term Period | yr			10
MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Tiers | tiers		3
TSR measurement (in years) | yr		3
Distributions percent before measurement date		10.00%
Indices Used to Compare TSR | indices		2
Percentage of annualized TSR for Reduction of Earned Awards		0.00%
Percentage to Cause Some Awards to be Earned Even if on a Relative Basis it Would Not Result in any Earned Awards		12.00%
MYLTIP units issued | shares						375,000
Value of MYLTIP Awards		$ 15,700,000
MYLTIP Value Amortized Into Earnings, Years | yr		4
Minimum [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned		$ 0
Maximum [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned		40,800,000
Threshold [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier		8,200,000
Target [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier		16,300,000
High [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier		$ 40,800,000
Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares) | shares							24,231
MYLTIP units issued | shares							38,926
Non-qualified stock options issued (in shares) | shares							50,847
Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash Payment Related to Transition Agreement								$ 6,700,000
Target Equity Award Compensation Associated with Transition Agreement								$ 11,100,000
Compensation Expense associated with Transition Agreement				$ 3,900,000	$ 13,800,000
Acceleration of Stock Based Compensation in Association with Transition Agreement					$ 12,900,000
Cohen & Steers Realty Majors Portfolio Index [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Percentage of Index Used to Compare to TSR		50.00%
NAREIT Office Index adjusted [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Percentage of Index Used to Compare to TSR		50.00%
MYLTIP Vesting 2018 [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage		50.00%
MYLTIP vesting 2019 [Member] | MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage		50.00%

Stock Option and Incentive Pl97

Stock Option and Incentive Plan (Restricted Stock) (Narrative) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)dVestingInstallments$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)$ / sharesshares	May. 20, 2014shares	Apr. 02, 2013shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued	153,658,866	153,192,845		7,542
Stock-based compensation associated with restricted stock, non-qualified options, LTIP Units, 2012 OPP Units, and 2013, 2014 and 2015 MYLTIP Units | $	$ 26,900	$ 26,000	$ 43,900
Value of shares of common stock | $	1,536	$ 1,531
Weighted-average grant date fair value (in dollars per share) | $ / shares			$ 104.50
Exercisable, Weighted Average Exercise Price | $ / shares		$ 96.91	$ 98.83
Total intrinsic value of the outstanding and exercisable stock options | $	$ 14,600
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued	34,150	23,968	36,730
Employee and director payment per share (in dollars per share) | $ / shares	$ 0.01
Value of shares of common stock | $	$ 4,800	$ 2,600	$ 3,900
Employee's weighted average cost per share (in dollars per share) | $ / shares	$ 140.88	$ 109.27	$ 105.30
LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares)	190,563	127,094	184,733
Value of LTIP units issued | $	$ 13,500	$ 12,800	$ 17,800
Per unit fair value weighted-average (in dollars per share) | $ / shares	$ 128.94	$ 100.61	$ 96.13
Expected life assumed to calculate per unit fair value per LTIP unit (years)	5 years 8 months 12 days	5 years 8 months 12 days	5 years 8 months 12 days
Risk-free rate	1.47%	1.84%	1.03%
Expected price volatility	26.00%	27.00%	26.00%
LTIPs And Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting annual installments | VestingInstallments	4
LTIPS, Restricted Stock and 2012 OPP Units [Member] [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses | $	$ 18,300
2013, 2014 and 2015 MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses | $	$ 17,800
Weighted-average period (years)	2 years 4 months 24 days
LTIPs, OPP and MYLTIP Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share) | $ / shares	$ 0.25
MYLTIP 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued			318,926
MYLTIP 2014[Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued		485,459
MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued	375,000
Non Qualified Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-qualified stock options issued (in shares)			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%
Weighted-average grant date fair value (in dollars per share) | $ / shares			$ 18.46
Weighted-average exercise price (in dollars per share) | $ / shares			$ 105.10
Non-Qualified Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum Common Stock available for issuance	250,000
Employee Common Stock options, percent of average closing price	85.00%
Number Of Days Used In Calculation, Average Closing Prices Of Common Stock | d	10
Shares issued	6,199	6,964	6,442
Shares issued, weighted-average purchase price per share | $ / shares	$ 108.73	$ 93.37	$ 89.65
Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares)					24,231
Non-qualified stock options issued (in shares)					50,847
MYLTIP units issued					38,926
Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation associated with restricted stock, non-qualified options, LTIP Units, 2012 OPP Units, and 2013, 2014 and 2015 MYLTIP Units | $		$ 2,500	$ 21,500
Non-executive Chairman of the Board of Directors [Member] | LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares)	85,962

Stock Option and Incentive Pl98

Stock Option and Incentive Plan Schedule of Stock Options Status (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning Outstanding, Shares	553,312	558,823	294,527
Beginning Oustanding, Weighted Average Exercise Price	$ 97.21	$ 100.43	$ 101.06
Granted, Shares			252,220
Granted, Weighted Average Exercise Price			$ 104.50
Exercised, Shares	(11,447)	(21,459)
Exercised, Weighted Averge Exercise Price	$ 92.50	$ 97.04
Canceled, Shares		(2,444)
Canceled, Weighted Average Exercise Price		$ 103.57
Special dividend adjustment (shares)	5,264	18,392	12,076
Special dividend adjustment weighted average exercise price	$ 96.38	$ 97.22	$ 100.44
Ending Outstanding, Shares	547,129	553,312	558,823
Ending Oustanding, Weighted Average Exercise Pric	$ 96.38	$ 97.21	$ 100.43

Stock Option and Incentive Pl99

Stock Option and Incentive Plan Schedule of Stock Options Outstanding (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding at period end	547,129	553,312	558,823	294,527
Outstanding, Weighted Average Exercise Price	$ 96.38	$ 97.21	$ 100.43	$ 101.06
Number Exercisable		411,143	199,868
Exercisable, Weighted Average Exercise Price		$ 96.91	$ 98.83
Exercise Price of $86.86 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life (Years)	5 years 1 month 6 days
Number Outstanding at period end	118,502
Outstanding, Weighted Average Exercise Price	$ 86.86
Number Exercisable	118,502
Exercisable, Weighted Average Exercise Price	$ 86.86
Exercise Price of $95.69 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life (Years)	7 years 3 months 18 days
Number Outstanding at period end	54,282
Outstanding, Weighted Average Exercise Price	$ 95.69
Number Exercisable	27,141
Exercisable, Weighted Average Exercise Price	$ 95.69
Exercise Price of $98.46 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life (Years)	7 years 1 month 6 days
Number Outstanding at period end	206,728
Outstanding, Weighted Average Exercise Price	$ 98.46
Number Exercisable	168,332
Exercisable, Weighted Average Exercise Price	$ 98.46
Exercise Price of $100.77 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life (Years)	6 years 1 month 6 days
Number Outstanding at period end	167,617
Outstanding, Weighted Average Exercise Price	$ 100.77
Number Exercisable	151,396
Exercisable, Weighted Average Exercise Price	$ 100.77

Related Party Transactions (Det

Related Party Transactions (Details)	12 Months Ended
	Dec. 31, 2015USD ($)nonemployeedirectorsshares	Dec. 31, 2014USD ($)shares	Dec. 31, 2013USD ($)	May. 20, 2014shares
Related Party Transaction [Line Items]
Number Of Non employee Directors Electing To Receive Deferred Stock Units | nonemployeedirectors	6
Shares issued | shares	153,658,866	153,192,845		7,542
Deferred Stock Units Outstanding	93,044	84,435
Executive Vice President and New York regional manager [Member]
Related Party Transaction [Line Items]
Aggregate leasing commissions paid to related parties	$ 616,000	$ 1,214,000	$ 592,000
Brother of Senior Executive Vice President [Member]
Related Party Transaction [Line Items]
Aggregate leasing commissions paid to related parties	$ 384,000	$ 674,000	$ 868,000

Selected Interim Financial I101

Selected Interim Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Total revenue	$ 624,240	$ 629,884	$ 618,221	$ 618,476	$ 613,707	$ 618,803	$ 589,794	$ 574,694	$ 2,490,821	$ 2,396,998	$ 2,135,539
Income before gains on sales of real estate	85,406	123,792	100,739	114,086	85,323	109,038	95,901	67,756	424,023	358,018	703,648
Net income attributable to the Company	$ 137,851	$ 184,082	$ 79,460	$ 171,182	$ 174,510	$ 127,724	$ 76,527	$ 54,034	$ 583,106	$ 443,611	$ 749,811
Net income (in dollars per share / unit) - Basic	$ 0.90	$ 1.20	$ 0.52	$ 1.12	$ 1.14	$ 0.83	$ 0.50	$ 0.35	$ 3.73	$ 2.83	$ 4.87
Net income (in dollars per share / unit) - Diluted	$ 0.90	$ 1.20	$ 0.52	$ 1.11	$ 1.14	$ 0.83	$ 0.50	$ 0.35	$ 3.72	$ 2.83	$ 4.86
Boston Properties Limited Partnership [Member]
Total revenue	$ 624,240	$ 629,884	$ 618,221	$ 618,476	$ 613,707	$ 618,803	$ 589,794	$ 574,694	$ 2,490,821	$ 2,396,998	$ 2,135,539
Income before gains on sales of real estate	87,404	125,790	102,737	116,085	87,753	111,066	97,927	69,781	432,016	366,527	715,601
Net income attributable to the Company	$ 156,901	$ 207,626	$ 90,852	$ 193,369	$ 204,759	$ 144,715	$ 87,436	$ 62,219	$ 659,248	$ 509,629	$ 849,573
Net income (in dollars per share / unit) - Basic	$ 0.92	$ 1.21	$ 0.53	$ 1.13	$ 1.20	$ 0.85	$ 0.51	$ 0.37	$ 3.79	$ 2.93	$ 4.97
Net income (in dollars per share / unit) - Diluted	$ 0.92	$ 1.21	$ 0.53	$ 1.12	$ 1.20	$ 0.85	$ 0.51	$ 0.37	$ 3.78	$ 2.92	$ 4.97

Subsequent Events subsequent Ev

Subsequent Events subsequent Events (Details)	Feb. 04, 2016USD ($)	Feb. 03, 2016USD ($)ft²	Jan. 25, 2016USD ($)yrtiersindices	Jan. 20, 2016USD ($)	Jan. 06, 2016USD ($)yrswaps	Dec. 31, 2015USD ($)shares	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)shares	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)yrswapsshares	Dec. 31, 2014USD ($)shares	Dec. 31, 2013USD ($)	Feb. 08, 2016shares	Feb. 01, 2016USD ($)ft²	May. 20, 2014shares
Subsequent Event [Line Items]
Common stock, shares issued | shares						153,658,866				153,192,845				153,658,866	153,192,845				7,542
Proceeds from unsecured senior notes														$ 0	$ 0	$ 1,194,753,000
Repayments of Unsecured Debt														0	548,016,000	0
Revenue from a terminated tenant						$ 624,240,000	$ 629,884,000	$ 618,221,000	$ 618,476,000	$ 613,707,000	$ 618,803,000	$ 589,794,000	$ 574,694,000	$ 2,490,821,000	2,396,998,000	2,135,539,000
Subsequent Event [Member]
Subsequent Event [Line Items]
LTIP units issued (in shares) | shares																	139,435
Subsequent Event [Member] | MYLTIP 2016 [Member]
Subsequent Event [Line Items]
Indices Used to Compare TSR | indices			2
Number of Tiers | tiers			3
Percentage of annualized TSR for Reduction of Earned Awards			0.00%
Percentage to Cause Some Awards to be Earned Even if on a Relative Basis it Would Not Result in any Earned Awards			12.00%
Distributions percent before measurement date			10.00%
Value of MYLTIP Awards			$ 17,300,000
MYLTIP Value Amortized Into Earnings, Years | yr			4
TSR measurement (in years) | yr			3
Subsequent Event [Member] | MYLTIP 2016 [Member] | Cohen & Steers Realty Majors Portfolio Index [Member]
Subsequent Event [Line Items]
Weighted Percentage of Index Used to Compare to TSR			50.00%
Subsequent Event [Member] | MYLTIP 2016 [Member] | NAREIT Office Index adjusted [Member]
Subsequent Event [Line Items]
Weighted Percentage of Index Used to Compare to TSR			50.00%
Subsequent Event [Member] | MYLTIP 2013 [Member]
Subsequent Event [Line Items]
Final awards percentage of target	109.50%
Value of MYLTIP Awards	$ 13,500,000
TSR performance on an annualized compounded basis	8.50%
Subsequent Event [Member] | MYLTIP 2013 [Member] | Cohen & Steers Realty Majors Portfolio Index [Member]
Subsequent Event [Line Items]
TSR performance on an annualized compounded basis	9.40%
Subsequent Event [Member] | MYLTIP 2013 [Member] | NAREIT Office Index adjusted [Member]
Subsequent Event [Line Items]
TSR performance on an annualized compounded basis	6.20%
Subsequent Event [Member] | High [Member] | MYLTIP 2016 [Member]
Subsequent Event [Line Items]
Amount of Each Tier			$ 49,300,000
Subsequent Event [Member] | Minimum [Member] | MYLTIP 2016 [Member]
Subsequent Event [Line Items]
Potential Awards Earned			0
Subsequent Event [Member] | Maximum [Member] | MYLTIP 2016 [Member]
Subsequent Event [Line Items]
Potential Awards Earned			49,300,000
Subsequent Event [Member] | Threshold [Member] | MYLTIP 2016 [Member]
Subsequent Event [Line Items]
Amount of Each Tier			9,900,000
Subsequent Event [Member] | Target [Member] | MYLTIP 2016 [Member]
Subsequent Event [Line Items]
Amount of Each Tier			$ 19,700,000
Subsequent Event [Member] | MYLTIP vesting 2019 | MYLTIP 2016 [Member]
Subsequent Event [Line Items]
Vesting Percentage			50.00%
Subsequent Event [Member] | MYLTIP vesting 2020 | MYLTIP 2016 [Member]
Subsequent Event [Line Items]
Vesting Percentage			50.00%
Subsequent Event [Member] | Restricted Stock [Member]
Subsequent Event [Line Items]
Common stock, shares issued | shares																	18,521
415 Main Street | Subsequent Event [Member]
Subsequent Event [Line Items]
Sale Price Of Sold Property																		$ 105,400,000
Net Rentable Area | ft²																		231,000
767 Fifth Partners LLC [Member]
Subsequent Event [Line Items]
Ownership Percentage by Parent						60.00%								60.00%
767 Fifth Partners LLC [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Ownership Percentage by Parent					60.00%
Interest Rate Swap [Member]
Subsequent Event [Line Items]
Derivative, Notional Amount						$ 950,000,000								$ 950,000,000
Interest Rate Swap [Member] | 767 Fifth Partners LLC [Member]
Subsequent Event [Line Items]
Number of interest rate swap agreements entered into | swaps														14
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) | yr														10
Derivative, Average Fixed Interest Rate						2.646%								2.646%
Derivative, Notional Amount						$ 400,000,000								$ 400,000,000
Interest Rate Swap [Member] | 767 Fifth Partners LLC [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of interest rate swap agreements entered into | swaps					2
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) | yr					10
Derivative, Average Fixed Interest Rate					2.403%
Derivative, Notional Amount					$ 50,000,000
Boston Properties Limited Partnership [Member]
Subsequent Event [Line Items]
Proceeds from unsecured senior notes														0	0	1,194,753,000
Repayments of Unsecured Debt														0	548,016,000	0
Revenue from a terminated tenant						624,240,000	$ 629,884,000	$ 618,221,000	$ 618,476,000	$ 613,707,000	$ 618,803,000	$ 589,794,000	$ 574,694,000	2,490,821,000	$ 2,396,998,000	$ 2,135,539,000
Senior Notes [Member] | Boston Properties Limited Partnership [Member]
Subsequent Event [Line Items]
Principal Amount						$ 5,300,000,000								$ 5,300,000,000
Senior Notes [Member] | Unsecured senior note 3.766% [Member] | Boston Properties Limited Partnership [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Coupon/Stated Rate				3.65%
Proceeds from unsecured senior notes				$ 988,900,000
Principal Amount				$ 1,000,000,000
Senior Notes Pricing				99.708%
Effective Rate				3.766%
Terminated lease at 250 West 55th Street in NYC [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Net Rentable Area | ft²		85,000
Revenue from a terminated tenant		$ 45,000,000

Real Estate and Accumulated 103

Real Estate and Accumulated Depreciation Schedule of Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	[1]	$ 3,438,714
Original Land		4,602,809
Original Building		11,248,289
Costs Capitalized Subsequent to Acquisition		3,600,585
Land and improvements		4,806,021
Buildings and Improvements		13,629,532
Land Held for Development		252,195
Development and Construction in Progress		763,935
Total		19,451,683
Accumulated Depreciation		3,905,940
Furniture, fixtures and equipment		29,852	$ 27,986
Furniture, fixtures and equipment accumulated depreciation		19,954
Real Estate Aggregate Cost For Tax Purposes		15,000,000
Real Estate Aggregate Accumulated Depreciation For Tax Purposes		$ 3,000,000
Real Estate and Accumulated Depreciation, Life Used for Depreciation		40 years
Unamortized balance of historical fair value adjustments		$ 80,235
767 Fifth Avenue (the General Motors Building)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		767 Fifth Avenue (the General Motors Building)
Type		Office
Location		New York, NY
Encumbrances		$ 1,377,986
Original Land		1,796,252
Original Building		1,532,654
Costs Capitalized Subsequent to Acquisition		45,800
Land and improvements		1,796,252
Buildings and Improvements		1,578,454
Land Held for Development		0
Development and Construction in Progress		0
Total		3,374,706
Accumulated Depreciation		$ 128,488
Year(s) built / renovated		1,968
Depreciable Lives (Years)	[2]	(1)
Embarcadero Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Embarcadero Center
Type		Office
Location		San Francisco, CA
Encumbrances		$ 348,886
Original Land		179,697
Original Building		847,410
Costs Capitalized Subsequent to Acquisition		332,276
Land and improvements		195,987
Buildings and Improvements		1,163,396
Land Held for Development		0
Development and Construction in Progress		0
Total		1,359,383
Accumulated Depreciation		$ 542,103
Year(s) built / renovated		1970/1989
Depreciable Lives (Years)	[2]	(1)
Prudential Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Prudential Center
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		92,077
Original Building		734,594
Costs Capitalized Subsequent to Acquisition		526,740
Land and improvements		107,426
Buildings and Improvements		1,082,583
Land Held for Development		1,714
Development and Construction in Progress		161,688
Total		1,353,411
Accumulated Depreciation		$ 446,792
Year(s) built / renovated		1965/1993/2002
Depreciable Lives (Years)	[2]	(1)
399 Park Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		399 Park Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		339,200
Original Building		700,358
Costs Capitalized Subsequent to Acquisition		110,972
Land and improvements		354,107
Buildings and Improvements		796,423
Land Held for Development		0
Development and Construction in Progress		0
Total		1,150,530
Accumulated Depreciation		$ 265,266
Year(s) built / renovated		1,961
Depreciable Lives (Years)	[2]	(1)
200 Clarendon Street and Garage (formerly The John Hancock Tower and Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		200 Clarendon Street and Garage (formerly the John Hancock Tower and Garage)
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		219,543
Original Building		667,884
Costs Capitalized Subsequent to Acquisition		112,229
Land and improvements		219,616
Buildings and Improvements		776,755
Land Held for Development		3,285
Development and Construction in Progress		0
Total		999,656
Accumulated Depreciation		$ 128,815
Year(s) built / renovated		1,976
Depreciable Lives (Years)	[2]	(1)
601 Lexington Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		601 Lexington Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 699,061
Original Land		241,600
Original Building		494,782
Costs Capitalized Subsequent to Acquisition		231,812
Land and improvements		289,639
Buildings and Improvements		677,238
Land Held for Development		1,317
Development and Construction in Progress		0
Total		968,194
Accumulated Depreciation		$ 250,128
Year(s) built / renovated		1977/1997
Depreciable Lives (Years)	[2]	(1)
250 West 55th Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		250 West 55th Street
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		285,263
Original Building		603,167
Costs Capitalized Subsequent to Acquisition		16,488
Land and improvements		285,263
Buildings and Improvements		619,655
Land Held for Development		0
Development and Construction in Progress		0
Total		904,918
Accumulated Depreciation		$ 28,349
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[2]	(1)
Times Square Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Times Square Tower
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		165,413
Original Building		380,438
Costs Capitalized Subsequent to Acquisition		84,722
Land and improvements		169,193
Buildings and Improvements		461,380
Land Held for Development		0
Development and Construction in Progress		0
Total		630,573
Accumulated Depreciation		$ 164,767
Year(s) built / renovated		2,004
Depreciable Lives (Years)	[2]	(1)
Carnegie Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Carnegie Center
Type		Office
Location		Princeton, NJ
Encumbrances		$ 0
Original Land		105,107
Original Building		377,259
Costs Capitalized Subsequent to Acquisition		128,069
Land and improvements		103,064
Buildings and Improvements		464,086
Land Held for Development		2,475
Development and Construction in Progress		40,810
Total		610,435
Accumulated Depreciation		$ 198,387
Year(s) built / renovated		1983-1999
Depreciable Lives (Years)	[2]	(1)
100 Federal Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		100 Federal Street
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		131,067
Original Building		435,954
Costs Capitalized Subsequent to Acquisition		15,555
Land and improvements		131,067
Buildings and Improvements		450,933
Land Held for Development		576
Development and Construction in Progress		0
Total		582,576
Accumulated Depreciation		$ 60,125
Year(s) built / renovated		1971-1975
Depreciable Lives (Years)	[2]	(1)
Atlantic Wharf
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Atlantic Wharf
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		63,988
Original Building		454,537
Costs Capitalized Subsequent to Acquisition		16,376
Land and improvements		63,988
Buildings and Improvements		470,913
Land Held for Development		0
Development and Construction in Progress		0
Total		534,901
Accumulated Depreciation		$ 70,552
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[2]	(1)
510 Madison Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		510 Madison Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		103,000
Original Building		253,665
Costs Capitalized Subsequent to Acquisition		19,575
Land and improvements		103,000
Buildings and Improvements		273,240
Land Held for Development		0
Development and Construction in Progress		0
Total		376,240
Accumulated Depreciation		$ 34,640
Year(s) built / renovated		2,012
Depreciable Lives (Years)	[2]	(1)
Fountain Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Fountain Square
Type		Office
Location		Reston, VA
Encumbrances		$ 213,499
Original Land		56,853
Original Building		306,298
Costs Capitalized Subsequent to Acquisition		12,459
Land and improvements		56,853
Buildings and Improvements		318,757
Land Held for Development		0
Development and Construction in Progress		0
Total		375,610
Accumulated Depreciation		$ 39,508
Year(s) built / renovated		1986-1990
Depreciable Lives (Years)	[2]	(1)
599 Lexington Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		599 Lexington Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 750,000
Original Land		81,040
Original Building		100,507
Costs Capitalized Subsequent to Acquisition		149,551
Land and improvements		87,852
Buildings and Improvements		243,246
Land Held for Development		0
Development and Construction in Progress		0
Total		331,098
Accumulated Depreciation		$ 160,354
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[2]	(1)
680 Folsom Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		680 Folsom Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		72,545
Original Building		219,766
Costs Capitalized Subsequent to Acquisition		7,348
Land and improvements		72,545
Buildings and Improvements		227,114
Land Held for Development		0
Development and Construction in Progress		0
Total		299,659
Accumulated Depreciation		$ 13,091
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[2]	(1)
South of Market and Democracy Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		South of Market and Democracy Tower
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		13,603
Original Building		237,479
Costs Capitalized Subsequent to Acquisition		11,977
Land and improvements		13,687
Buildings and Improvements		249,372
Land Held for Development		0
Development and Construction in Progress		0
Total		263,059
Accumulated Depreciation		$ 70,437
Year(s) built / renovated		2008-2009
Depreciable Lives (Years)	[2]	(1)
Bay Colony Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Bay Colony Corporate Center
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		18,789
Original Building		148,451
Costs Capitalized Subsequent to Acquisition		65,997
Land and improvements		18,789
Buildings and Improvements		214,448
Land Held for Development		0
Development and Construction in Progress		0
Total		233,237
Accumulated Depreciation		$ 40,812
Year(s) built / renovated		1985-1989
Depreciable Lives (Years)	[2]	(1)
Gateway Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Gateway Center
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		28,255
Original Building		139,245
Costs Capitalized Subsequent to Acquisition		54,027
Land and improvements		30,627
Buildings and Improvements		190,900
Land Held for Development		0
Development and Construction in Progress		0
Total		221,527
Accumulated Depreciation		$ 94,083
Year(s) built / renovated		1984/1986/2002
Depreciable Lives (Years)	[2]	(1)
535 Mission Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		535 Mission Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		40,933
Original Building		148,378
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		40,933
Buildings and Improvements		148,378
Land Held for Development		0
Development and Construction in Progress		0
Total		189,311
Accumulated Depreciation		$ 3,221
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[2]	(1)
2200 Pennsylvania Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2200 Pennsylvania Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		0
Original Building		183,541
Costs Capitalized Subsequent to Acquisition		5,230
Land and improvements		0
Buildings and Improvements		188,771
Land Held for Development		0
Development and Construction in Progress		0
Total		188,771
Accumulated Depreciation		$ 33,039
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[2]	(1)
Mountain View Research Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Mountain View Research Park
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		95,066
Original Building		68,373
Costs Capitalized Subsequent to Acquisition		5,581
Land and improvements		95,066
Buildings and Improvements		73,954
Land Held for Development		0
Development and Construction in Progress		0
Total		169,020
Accumulated Depreciation		$ 9,581
Year(s) built / renovated		1977-1981/2007-2013
Depreciable Lives (Years)	[2]	(1)
Reservoir Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reservoir Place
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		18,605
Original Building		92,619
Costs Capitalized Subsequent to Acquisition		46,547
Land and improvements		20,118
Buildings and Improvements		128,975
Land Held for Development		0
Development and Construction in Progress		8,678
Total		157,771
Accumulated Depreciation		$ 57,706
Year(s) built / renovated		1955/1987
Depreciable Lives (Years)	[2]	(1)
1333 New Hampshire Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		1333 New Hampshire Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		34,032
Original Building		85,660
Costs Capitalized Subsequent to Acquisition		10,841
Land and improvements		35,382
Buildings and Improvements		95,151
Land Held for Development		0
Development and Construction in Progress		0
Total		130,533
Accumulated Depreciation		$ 35,457
Year(s) built / renovated		1,996
Depreciable Lives (Years)	[2]	(1)
Kingstowne Towne Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kingstowne Towne Center
Type		Office
Location		Alexandria, VA
Encumbrances		$ 0
Original Land		18,021
Original Building		109,038
Costs Capitalized Subsequent to Acquisition		1,276
Land and improvements		18,062
Buildings and Improvements		110,273
Land Held for Development		0
Development and Construction in Progress		0
Total		128,335
Accumulated Depreciation		$ 33,374
Year(s) built / renovated		2003-2006
Depreciable Lives (Years)	[2]	(1)
1330 Connecticut Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		1330 Connecticut Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		25,982
Original Building		82,311
Costs Capitalized Subsequent to Acquisition		19,098
Land and improvements		27,135
Buildings and Improvements		100,256
Land Held for Development		0
Development and Construction in Progress		0
Total		127,391
Accumulated Depreciation		$ 45,063
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
Capital Gallery
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Capital Gallery
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		4,725
Original Building		29,565
Costs Capitalized Subsequent to Acquisition		88,569
Land and improvements		8,662
Buildings and Improvements		114,197
Land Held for Development		0
Development and Construction in Progress		0
Total		122,859
Accumulated Depreciation		$ 57,489
Year(s) built / renovated		1981/2006
Depreciable Lives (Years)	[2]	(1)
Weston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Weston Corporate Center
Type		Office
Location		Weston, MA
Encumbrances		$ 0
Original Land		25,753
Original Building		92,312
Costs Capitalized Subsequent to Acquisition		(123)
Land and improvements		25,854
Buildings and Improvements		92,088
Land Held for Development		0
Development and Construction in Progress		0
Total		117,942
Accumulated Depreciation		$ 17,023
Year(s) built / renovated		2,010
Depreciable Lives (Years)	[2]	(1)
One Freedom Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		One Freedom Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		9,929
Original Building		84,504
Costs Capitalized Subsequent to Acquisition		19,613
Land and improvements		11,293
Buildings and Improvements		102,753
Land Held for Development		0
Development and Construction in Progress		0
Total		114,046
Accumulated Depreciation		$ 41,106
Year(s) built / renovated		2,000
Depreciable Lives (Years)	[2]	(1)
Two Freedom Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Two Freedom Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		13,930
Original Building		77,739
Costs Capitalized Subsequent to Acquisition		21,374
Land and improvements		15,420
Buildings and Improvements		97,623
Land Held for Development		0
Development and Construction in Progress		0
Total		113,043
Accumulated Depreciation		$ 41,164
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
One and Two Reston Overlook
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		One and Two Reston Overlook
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		16,456
Original Building		66,192
Costs Capitalized Subsequent to Acquisition		22,385
Land and improvements		16,179
Buildings and Improvements		88,854
Land Held for Development		0
Development and Construction in Progress		0
Total		105,033
Accumulated Depreciation		$ 37,165
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[2]	(1)
Discovery Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Discovery Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		11,198
Original Building		71,782
Costs Capitalized Subsequent to Acquisition		21,234
Land and improvements		12,533
Buildings and Improvements		91,681
Land Held for Development		0
Development and Construction in Progress		0
Total		104,214
Accumulated Depreciation		$ 35,835
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
415 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		415 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		3,457
Original Building		97,136
Costs Capitalized Subsequent to Acquisition		2,986
Land and improvements		4,125
Buildings and Improvements		99,454
Land Held for Development		0
Development and Construction in Progress		0
Total		103,579
Accumulated Depreciation		$ 59,405
Year(s) built / renovated		2,006
Depreciable Lives (Years)	[2]	(1)
355 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		355 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		18,863
Original Building		53,346
Costs Capitalized Subsequent to Acquisition		28,822
Land and improvements		21,173
Buildings and Improvements		79,858
Land Held for Development		0
Development and Construction in Progress		0
Total		101,031
Accumulated Depreciation		$ 23,372
Year(s) built / renovated		1981/1996/2013
Depreciable Lives (Years)	[2]	(1)
140 Kendrick Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		140 Kendrick Street
Type		Office
Location		Needham, MA
Encumbrances		$ 0
Original Land		18,095
Original Building		66,905
Costs Capitalized Subsequent to Acquisition		15,075
Land and improvements		19,092
Buildings and Improvements		80,983
Land Held for Development		0
Development and Construction in Progress		0
Total		100,075
Accumulated Depreciation		$ 23,191
Year(s) built / renovated		2,000
Depreciable Lives (Years)	[2]	(1)
90 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		90 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		19,104
Original Building		52,078
Costs Capitalized Subsequent to Acquisition		17,386
Land and improvements		20,785
Buildings and Improvements		67,783
Land Held for Development		0
Development and Construction in Progress		0
Total		88,568
Accumulated Depreciation		$ 14,394
Year(s) built / renovated		1983/1998/2013
Depreciable Lives (Years)	[2]	(1)
230 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		230 CityPoint
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		13,189
Original Building		49,823
Costs Capitalized Subsequent to Acquisition		18,800
Land and improvements		13,593
Buildings and Improvements		68,219
Land Held for Development		0
Development and Construction in Progress		0
Total		81,812
Accumulated Depreciation		$ 20,265
Year(s) built / renovated		1,992
Depreciable Lives (Years)	[2]	(1)
Waltham Weston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Waltham Weston Corporate Center
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		10,385
Original Building		60,694
Costs Capitalized Subsequent to Acquisition		8,907
Land and improvements		11,097
Buildings and Improvements		68,889
Land Held for Development		0
Development and Construction in Progress		0
Total		79,986
Accumulated Depreciation		$ 24,699
Year(s) built / renovated		2,003
Depreciable Lives (Years)	[2]	(1)
77 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		77 CityPoint
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		13,847
Original Building		60,383
Costs Capitalized Subsequent to Acquisition		5,605
Land and improvements		13,873
Buildings and Improvements		65,962
Land Held for Development		0
Development and Construction in Progress		0
Total		79,835
Accumulated Depreciation		$ 18,930
Year(s) built / renovated		2,008
Depreciable Lives (Years)	[2]	(1)
North First Business Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		North First Business Park
Type		Office
Location		San Jose, CA
Encumbrances		$ 0
Original Land		58,402
Original Building		13,069
Costs Capitalized Subsequent to Acquisition		4,028
Land and improvements		23,377
Buildings and Improvements		16,214
Land Held for Development		35,908
Development and Construction in Progress		0
Total		75,499
Accumulated Depreciation		$ 14,139
Year(s) built / renovated		1,981
Depreciable Lives (Years)	[2]	(1)
300 Binney Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		300 Binney Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		18,080
Original Building		51,262
Costs Capitalized Subsequent to Acquisition		140
Land and improvements		18,080
Buildings and Improvements		51,402
Land Held for Development		0
Development and Construction in Progress		0
Total		69,482
Accumulated Depreciation		$ 4,375
Year(s) built / renovated		2,013
Depreciable Lives (Years)	[2]	(1)
2440 West El Camino Real
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2440 West El Camino Real
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		16,741
Original Building		51,285
Costs Capitalized Subsequent to Acquisition		1,422
Land and improvements		16,741
Buildings and Improvements		52,707
Land Held for Development		0
Development and Construction in Progress		0
Total		69,448
Accumulated Depreciation		$ 8,185
Year(s) built / renovated		1987/2003
Depreciable Lives (Years)	[2]	(1)
Reston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Corporate Center
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		9,135
Original Building		50,857
Costs Capitalized Subsequent to Acquisition		6,464
Land and improvements		10,148
Buildings and Improvements		56,308
Land Held for Development		0
Development and Construction in Progress		0
Total		66,456
Accumulated Depreciation		$ 23,962
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
Wisconsin Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Wisconsin Place
Type		Office
Location		Chevy Chase, MD
Encumbrances		$ 0
Original Land		0
Original Building		53,349
Costs Capitalized Subsequent to Acquisition		12,787
Land and improvements		0
Buildings and Improvements		66,136
Land Held for Development		0
Development and Construction in Progress		0
Total		66,136
Accumulated Depreciation		$ 18,272
Year(s) built / renovated		2,009
Depreciable Lives (Years)	[2]	(1)
New Dominion Technology Park, Bldg. Two
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		New Dominion Technology Park, Bldg. Two
Type		Office
Location		Herndon, VA
Encumbrances		$ 0
Original Land		5,584
Original Building		51,868
Costs Capitalized Subsequent to Acquisition		3,911
Land and improvements		6,510
Buildings and Improvements		54,853
Land Held for Development		0
Development and Construction in Progress		0
Total		61,363
Accumulated Depreciation		$ 20,110
Year(s) built / renovated		2,004
Depreciable Lives (Years)	[2]	(1)
Sumner Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Sumner Square
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		624
Original Building		28,745
Costs Capitalized Subsequent to Acquisition		26,196
Land and improvements		1,478
Buildings and Improvements		54,087
Land Held for Development		0
Development and Construction in Progress		0
Total		55,565
Accumulated Depreciation		$ 26,923
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
200 West Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		200 West Street
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		16,148
Original Building		24,983
Costs Capitalized Subsequent to Acquisition		10,102
Land and improvements		16,813
Buildings and Improvements		34,420
Land Held for Development		0
Development and Construction in Progress		0
Total		51,233
Accumulated Depreciation		$ 18,034
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[2]	(1)
New Dominion Technology Park, Bldg. One
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		New Dominion Technology Park, Bldg. One
Type		Office
Location		Herndon, VA
Encumbrances		$ 38,494
Original Land		3,880
Original Building		43,227
Costs Capitalized Subsequent to Acquisition		3,883
Land and improvements		4,583
Buildings and Improvements		46,407
Land Held for Development		0
Development and Construction in Progress		0
Total		50,990
Accumulated Depreciation		$ 22,760
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
191 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		191 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		2,850
Original Building		27,166
Costs Capitalized Subsequent to Acquisition		18,610
Land and improvements		3,151
Buildings and Improvements		45,475
Land Held for Development		0
Development and Construction in Progress		0
Total		48,626
Accumulated Depreciation		$ 32,535
Year(s) built / renovated		1971/1995
Depreciable Lives (Years)	[2]	(1)
University Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		University Place
Type		Office
Location		Cambridge, MA
Encumbrances		$ 10,788
Original Land		0
Original Building		37,091
Costs Capitalized Subsequent to Acquisition		9,483
Land and improvements		390
Buildings and Improvements		46,184
Land Held for Development		0
Development and Construction in Progress		0
Total		46,574
Accumulated Depreciation		$ 23,635
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
Quorum Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2600 Tower Oaks Boulevard
Type		Office
Location		Rockville, MD
Encumbrances		$ 0
Original Land		4,243
Original Building		31,125
Costs Capitalized Subsequent to Acquisition		8,656
Land and improvements		4,785
Buildings and Improvements		39,239
Land Held for Development		0
Development and Construction in Progress		0
Total		44,024
Accumulated Depreciation		$ 18,386
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
255 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		255 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		134
Original Building		25,110
Costs Capitalized Subsequent to Acquisition		18,559
Land and improvements		548
Buildings and Improvements		43,255
Land Held for Development		0
Development and Construction in Progress		0
Total		43,803
Accumulated Depreciation		$ 27,153
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[2]	(1)
Quorum Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Quorum Office Park
Type		Office
Location		Chelmsford, MA
Encumbrances		$ 0
Original Land		3,750
Original Building		32,454
Costs Capitalized Subsequent to Acquisition		5,814
Land and improvements		5,187
Buildings and Improvements		36,831
Land Held for Development		0
Development and Construction in Progress		0
Total		42,018
Accumulated Depreciation		$ 14,671
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
500 E Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		500 E Street
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		109
Original Building		22,420
Costs Capitalized Subsequent to Acquisition		13,144
Land and improvements		2,379
Buildings and Improvements		33,294
Land Held for Development		0
Development and Construction in Progress		0
Total		35,673
Accumulated Depreciation		$ 22,616
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[2]	(1)
150 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		150 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		850
Original Building		25,042
Costs Capitalized Subsequent to Acquisition		8,623
Land and improvements		1,323
Buildings and Improvements		33,192
Land Held for Development		0
Development and Construction in Progress		0
Total		34,515
Accumulated Depreciation		$ 14,073
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[2]	(1)
325 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		325 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		174
Original Building		12,200
Costs Capitalized Subsequent to Acquisition		12,368
Land and improvements		965
Buildings and Improvements		23,777
Land Held for Development		0
Development and Construction in Progress		0
Total		24,742
Accumulated Depreciation		$ 11,339
Year(s) built / renovated		1987/2013
Depreciable Lives (Years)	[2]	(1)
105 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		105 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,299
Original Building		12,943
Costs Capitalized Subsequent to Acquisition		7,177
Land and improvements		2,395
Buildings and Improvements		19,024
Land Held for Development		0
Development and Construction in Progress		0
Total		21,419
Accumulated Depreciation		$ 12,556
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[2]	(1)
40 Shattuck Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		40 Shattuck Road
Type		Office
Location		Andover, MA
Encumbrances		$ 0
Original Land		709
Original Building		14,740
Costs Capitalized Subsequent to Acquisition		3,184
Land and improvements		893
Buildings and Improvements		17,740
Land Held for Development		0
Development and Construction in Progress		0
Total		18,633
Accumulated Depreciation		$ 6,846
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
Lexington Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Lexington Office Park
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		998
Original Building		1,426
Costs Capitalized Subsequent to Acquisition		16,099
Land and improvements		1,264
Buildings and Improvements		17,259
Land Held for Development		0
Development and Construction in Progress		0
Total		18,523
Accumulated Depreciation		$ 11,730
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[2]	(1)
201 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		201 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		2,849
Original Building		15,303
Costs Capitalized Subsequent to Acquisition		(154)
Land and improvements		3,124
Buildings and Improvements		14,874
Land Held for Development		0
Development and Construction in Progress		0
Total		17,998
Accumulated Depreciation		$ 6,987
Year(s) built / renovated		1,997
Depreciable Lives (Years)	[2]	(1)
The Point (formerly 99 Third Avenue Retail)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Point (formerly 99 Third Avenue Retail)
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		6,395
Original Building		10,040
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		6,395
Buildings and Improvements		10,040
Land Held for Development		0
Development and Construction in Progress		0
Total		16,435
Accumulated Depreciation		$ 76
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[2]	(1)
91 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		91 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		784
Original Building		6,464
Costs Capitalized Subsequent to Acquisition		8,192
Land and improvements		941
Buildings and Improvements		14,499
Land Held for Development		0
Development and Construction in Progress		0
Total		15,440
Accumulated Depreciation		$ 8,525
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
92-100 Hayden Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		92-100 Hayden Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		594
Original Building		6,748
Costs Capitalized Subsequent to Acquisition		8,034
Land and improvements		802
Buildings and Improvements		14,574
Land Held for Development		0
Development and Construction in Progress		0
Total		15,376
Accumulated Depreciation		$ 11,412
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
690 Folsom Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		690 Folsom Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		3,219
Original Building		11,038
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		3,219
Buildings and Improvements		11,038
Land Held for Development		0
Development and Construction in Progress		0
Total		14,257
Accumulated Depreciation		$ 334
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[2]	(1)
195 West Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		195 West Street
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		1,611
Original Building		6,652
Costs Capitalized Subsequent to Acquisition		4,340
Land and improvements		1,858
Buildings and Improvements		10,745
Land Held for Development		0
Development and Construction in Progress		0
Total		12,603
Accumulated Depreciation		$ 7,071
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[2]	(1)
181 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		181 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		1,066
Original Building		9,520
Costs Capitalized Subsequent to Acquisition		1,993
Land and improvements		1,160
Buildings and Improvements		11,419
Land Held for Development		0
Development and Construction in Progress		0
Total		12,579
Accumulated Depreciation		$ 4,580
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[2]	(1)
33 Hayden Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		33 Hayden Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		266
Original Building		3,234
Costs Capitalized Subsequent to Acquisition		8,787
Land and improvements		425
Buildings and Improvements		11,862
Land Held for Development		0
Development and Construction in Progress		0
Total		12,287
Accumulated Depreciation		$ 6,586
Year(s) built / renovated		1,979
Depreciable Lives (Years)	[2]	(1)
145 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		145 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		121
Original Building		5,535
Costs Capitalized Subsequent to Acquisition		5,305
Land and improvements		324
Buildings and Improvements		10,637
Land Held for Development		0
Development and Construction in Progress		0
Total		10,961
Accumulated Depreciation		$ 7,864
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
7501 Boston Boulevard, Building Seven
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7501 Boston Boulevard, Building Seven
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		665
Original Building		9,273
Costs Capitalized Subsequent to Acquisition		520
Land and improvements		791
Buildings and Improvements		9,667
Land Held for Development		0
Development and Construction in Progress		0
Total		10,458
Accumulated Depreciation		$ 4,355
Year(s) built / renovated		1,997
Depreciable Lives (Years)	[2]	(1)
7435 Boston Boulevard, Building One
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7435 Boston Boulevard, Building One
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		392
Original Building		3,822
Costs Capitalized Subsequent to Acquisition		4,218
Land and improvements		659
Buildings and Improvements		7,773
Land Held for Development		0
Development and Construction in Progress		0
Total		8,432
Accumulated Depreciation		$ 6,052
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[2]	(1)
250 Binney Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		250 Binney Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		110
Original Building		4,483
Costs Capitalized Subsequent to Acquisition		3,593
Land and improvements		273
Buildings and Improvements		7,913
Land Held for Development		0
Development and Construction in Progress		0
Total		8,186
Accumulated Depreciation		$ 4,303
Year(s) built / renovated		1,983
Depreciable Lives (Years)	[2]	(1)
7450 Boston Boulevard, Building Three
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7450 Boston Boulevard, Building Three
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		1,165
Original Building		4,681
Costs Capitalized Subsequent to Acquisition		1,880
Land and improvements		1,430
Buildings and Improvements		6,296
Land Held for Development		0
Development and Construction in Progress		0
Total		7,726
Accumulated Depreciation		$ 3,226
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[2]	(1)
8000 Grainger Court, Building Five
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		8000 Grainger Court, Building Five
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		366
Original Building		4,282
Costs Capitalized Subsequent to Acquisition		2,684
Land and improvements		601
Buildings and Improvements		6,731
Land Held for Development		0
Development and Construction in Progress		0
Total		7,332
Accumulated Depreciation		$ 5,336
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
453 Ravendale Drive
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		453 Ravendale Drive
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		5,477
Original Building		1,090
Costs Capitalized Subsequent to Acquisition		235
Land and improvements		5,479
Buildings and Improvements		1,323
Land Held for Development		0
Development and Construction in Progress		0
Total		6,802
Accumulated Depreciation		$ 265
Year(s) built / renovated		1,977
Depreciable Lives (Years)	[2]	(1)
7500 Boston Boulevard, Building Six
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7500 Boston Boulevard, Building Six
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		138
Original Building		3,749
Costs Capitalized Subsequent to Acquisition		2,617
Land and improvements		406
Buildings and Improvements		6,098
Land Held for Development		0
Development and Construction in Progress		0
Total		6,504
Accumulated Depreciation		$ 4,499
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
7300 Boston Boulevard, Building Thirteen
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7300 Boston Boulevard, Building Thirteen
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		608
Original Building		4,773
Costs Capitalized Subsequent to Acquisition		709
Land and improvements		661
Buildings and Improvements		5,429
Land Held for Development		0
Development and Construction in Progress		0
Total		6,090
Accumulated Depreciation		$ 4,626
Year(s) built / renovated		2,002
Depreciable Lives (Years)	[2]	(1)
7601 Boston Boulevard, Building Eight
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7601 Boston Boulevard, Building Eight
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		200
Original Building		878
Costs Capitalized Subsequent to Acquisition		4,924
Land and improvements		551
Buildings and Improvements		5,451
Land Held for Development		0
Development and Construction in Progress		0
Total		6,002
Accumulated Depreciation		$ 3,849
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[2]	(1)
8000 Corporate Court, Building Eleven
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		8000 Corporate Court, Building Eleven
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		136
Original Building		3,071
Costs Capitalized Subsequent to Acquisition		1,615
Land and improvements		775
Buildings and Improvements		4,047
Land Held for Development		0
Development and Construction in Progress		0
Total		4,822
Accumulated Depreciation		$ 2,639
Year(s) built / renovated		1,989
Depreciable Lives (Years)	[2]	(1)
7375 Boston Boulevard, Building Ten
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7375 Boston Boulevard, Building Ten
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		23
Original Building		2,685
Costs Capitalized Subsequent to Acquisition		1,003
Land and improvements		93
Buildings and Improvements		3,618
Land Held for Development		0
Development and Construction in Progress		0
Total		3,711
Accumulated Depreciation		$ 2,464
Year(s) built / renovated		1,988
Depreciable Lives (Years)	[2]	(1)
7374 Boston Boulevard, Building Four
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7374 Boston Boulevard, Building Four
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		241
Original Building		1,605
Costs Capitalized Subsequent to Acquisition		1,735
Land and improvements		398
Buildings and Improvements		3,183
Land Held for Development		0
Development and Construction in Progress		0
Total		3,581
Accumulated Depreciation		$ 2,345
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
7451 Boston Boulevard, Building Two
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7451 Boston Boulevard, Building Two
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		249
Original Building		1,542
Costs Capitalized Subsequent to Acquisition		1,661
Land and improvements		613
Buildings and Improvements		2,839
Land Held for Development		0
Development and Construction in Progress		0
Total		3,452
Accumulated Depreciation		$ 2,233
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[2]	(1)
32 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		32 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		168
Original Building		1,943
Costs Capitalized Subsequent to Acquisition		1,193
Land and improvements		314
Buildings and Improvements		2,990
Land Held for Development		0
Development and Construction in Progress		0
Total		3,304
Accumulated Depreciation		$ 1,786
Year(s) built / renovated		1968-1979/1987
Depreciable Lives (Years)	[2]	(1)
164 Lexington Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		164 Lexington Road
Type		Office
Location		Billerica, MA
Encumbrances		$ 0
Original Land		592
Original Building		1,370
Costs Capitalized Subsequent to Acquisition		319
Land and improvements		643
Buildings and Improvements		1,638
Land Held for Development		0
Development and Construction in Progress		0
Total		2,281
Accumulated Depreciation		$ 786
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[2]	(1)
17 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		17 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		26
Original Building		150
Costs Capitalized Subsequent to Acquisition		614
Land and improvements		65
Buildings and Improvements		725
Land Held for Development		0
Development and Construction in Progress		0
Total		790
Accumulated Depreciation		$ 323
Year(s) built / renovated		1,968
Depreciable Lives (Years)	[2]	(1)
The Avant at Reston Town Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Avant at Reston Town Center
Type		Residential
Location		Reston, VA
Encumbrances		$ 0
Original Land		20,350
Original Building		91,995
Costs Capitalized Subsequent to Acquisition		813
Land and improvements		20,350
Buildings and Improvements		92,808
Land Held for Development		0
Development and Construction in Progress		0
Total		113,158
Accumulated Depreciation		$ 4,833
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[2]	(1)
The Lofts at Atlantic Wharf
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Lofts at Atlantic Wharf
Type		Residential
Location		Boston, MA
Encumbrances		$ 0
Original Land		3,529
Original Building		54,891
Costs Capitalized Subsequent to Acquisition		1,579
Land and improvements		3,529
Buildings and Improvements		56,470
Land Held for Development		0
Development and Construction in Progress		0
Total		59,999
Accumulated Depreciation		$ 6,596
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[2]	(1)
Boston Marriott Cambridge
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Boston Marriott Cambridge
Type		Hotel
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		478
Original Building		37,918
Costs Capitalized Subsequent to Acquisition		35,665
Land and improvements		1,201
Buildings and Improvements		72,860
Land Held for Development		0
Development and Construction in Progress		0
Total		74,061
Accumulated Depreciation		$ 48,162
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[2]	(1)
Kendall Center Green Garage (formerly Cambridge Center East Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Green Garage (formerly Cambridge Center East Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		35,035
Costs Capitalized Subsequent to Acquisition		4,254
Land and improvements		103
Buildings and Improvements		39,186
Land Held for Development		0
Development and Construction in Progress		0
Total		39,289
Accumulated Depreciation		$ 8,610
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
Kendall Center Yellow Garage (formerly Cambridge Center West Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Yellow Garage (formerly Cambridge Center West Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,256
Original Building		15,697
Costs Capitalized Subsequent to Acquisition		1,571
Land and improvements		1,434
Buildings and Improvements		17,090
Land Held for Development		0
Development and Construction in Progress		0
Total		18,524
Accumulated Depreciation		$ 4,269
Year(s) built / renovated		2,006
Depreciable Lives (Years)	[2]	(1)
Kendall Center Blue Garage (formerly Cambridge Center North Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Blue Garage (formerly Cambridge Center North Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,163
Original Building		11,633
Costs Capitalized Subsequent to Acquisition		2,770
Land and improvements		1,579
Buildings and Improvements		13,987
Land Held for Development		0
Development and Construction in Progress		0
Total		15,566
Accumulated Depreciation		$ 8,941
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[2]	(1)
Salesforce Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Salesforce Tower
Type		Development
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		429,767
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		429,767
Total		429,767
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
601 Massachusetts Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		601 Massachusetts Avenue
Type		Development
Location		Washington, DC
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		253,176
Land and improvements		95,322
Buildings and Improvements		140,791
Land Held for Development		0
Development and Construction in Progress		17,063
Total		253,176
Accumulated Depreciation		$ 1,531
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
10 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		10 CityPoint
Type		Development
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		70,389
Land and improvements		163
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		70,226
Total		70,389
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Reston Signature Site
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Signature Site
Type		Development
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		38,886
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		12,678
Development and Construction in Progress		26,208
Total		38,886
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Cambridge Residential / 88 Ames
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Cambridge Residential / 88 Ames
Type		Development
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		9,495
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		9,495
Total		9,495
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Springfield Metro Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Springfield Metro Center
Type		Land
Location		Springfield, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		34,870
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		34,870
Development and Construction in Progress		0
Total		34,870
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Tower Oaks Master Plan
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Tower Oaks Master Plan
Type		Land
Location		Rockville, MD
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		29,022
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		29,022
Development and Construction in Progress		0
Total		29,022
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Plaza at Almaden
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Plaza at Almaden
Type		Land
Location		San Jose, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		29,010
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		29,010
Development and Construction in Progress		0
Total		29,010
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
6601 & 6605 Springfield Center Drive
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		6601 & 6605 Springfield Center Drive
Type		Land
Location		Springfield, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		13,866
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		13,866
Development and Construction in Progress		0
Total		13,866
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
214 Third Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		214 Third Avenue
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		13,415
Land and improvements		0
Buildings and Improvements		132
Land Held for Development		13,283
Development and Construction in Progress		0
Total		13,415
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
103 Fourth Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		103 Fourth Avenue
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		11,927
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		11,927
Development and Construction in Progress		0
Total		11,927
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Reston Gateway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Gateway
Type		Land
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		10,294
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		10,294
Development and Construction in Progress		0
Total		10,294
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
20 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		20 CityPoint
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		10,258
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		10,258
Development and Construction in Progress		0
Total		10,258
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Reston Eastgate
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Eastgate
Type		Land
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		9,215
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		9,215
Development and Construction in Progress		0
Total		9,215
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Washingtonian North
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Washingtonian North
Type		Land
Location		Gaithersburg, MD
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		8,836
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		8,836
Development and Construction in Progress		0
Total		8,836
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Crane Meadow
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Crane Meadow
Type		Land
Location		Marlborough, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		8,727
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		8,727
Development and Construction in Progress		0
Total		8,727
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Broad Run Business Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Broad Run Business Park
Type		Land
Location		Loudoun County, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		6,399
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		6,399
Development and Construction in Progress		0
Total		6,399
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
North First Master Plan
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		North First Master Plan
Type		Land
Location		San Jose, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		2,999
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		2,999
Development and Construction in Progress		0
Total		2,999
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Fourth and Harrison (formerly 425 Fourth Street)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Fourth and Harrison (formerly 425 Fourth Street)
Type		Land
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		2,920
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		2,920
Development and Construction in Progress		0
Total		2,920
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Kendall Center Master Plan (formerly Cambridge Master Plan)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Master Plan (formerly Cambridge Master Plan)
Type		Land
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		1,403
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		1,403
Development and Construction in Progress		0
Total		1,403
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
30 Shattuck Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		30 Shattuck Road
Type		Land
Location		Andover, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		1,213
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		1,213
Development and Construction in Progress		0
Total		1,213
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life Used for Depreciation		life of the lease
[1]	Includes the unamortized balance of the historical fair value adjustment totaling approximately $80.2 million.
[2]	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.

Real Estate and Accumulated 104

Real Estate and Accumulated Depreciation Activity of Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Real Estate, Balance at the beginning of the year	$ 19,208,417	$ 18,953,601	$ 14,869,887
Real Estate, Additions to / improvements of real estate	700,792	594,296	4,410,622
Real Estate, Assets sold / written off	(457,526)	(339,480)	(326,908)
Real Estate, Balance at the end of the year	19,451,683	19,208,417	18,953,601
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Accumulated depreciation, Balance at beginning of the year	3,529,978	3,145,701	2,919,479
Accumulated depreciation, Depreciation expense	486,450	456,176	419,908
Accumulated depreciation, Assets sold / written off	(110,488)	(71,899)	(193,686)
Accumulated depreciation, Balance at end of the year	$ 3,905,940	$ 3,529,978	$ 3,145,701

Real Estate and Accumulated 105

Real Estate and Accumulated Depreciation Schedule of Real Estate and Accumulated Depreciation (BPLP) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	[1]	$ 3,438,714
Original Land		4,602,809
Original Building		11,248,289
Costs Capitalized Subsequent to Acquisition		3,600,585
Land and improvements		4,806,021
Buildings and Improvements		13,629,532
Land Held for Development		252,195
Development and Construction in Progress		763,935
Total		19,451,683
Accumulated Depreciation		3,905,940
Furniture, fixtures and equipment		29,852	$ 27,986
Furniture, fixtures and equipment accumulated depreciation		19,954
Real Estate Aggregate Cost For Tax Purposes		15,000,000
Real Estate Aggregate Accumulated Depreciation For Tax Purposes		$ 3,000,000
Real Estate and Accumulated Depreciation, Life Used for Depreciation		40 years
Unamortized balance of historical fair value adjustments		$ 80,235
767 Fifth Avenue (the General Motors Building)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		767 Fifth Avenue (the General Motors Building)
Type		Office
Location		New York, NY
Encumbrances		$ 1,377,986
Original Land		1,796,252
Original Building		1,532,654
Costs Capitalized Subsequent to Acquisition		45,800
Land and improvements		1,796,252
Buildings and Improvements		1,578,454
Land Held for Development		0
Development and Construction in Progress		0
Total		3,374,706
Accumulated Depreciation		$ 128,488
Year(s) built / renovated		1,968
Depreciable Lives (Years)	[2]	(1)
Prudential Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Prudential Center
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		92,077
Original Building		734,594
Costs Capitalized Subsequent to Acquisition		526,740
Land and improvements		107,426
Buildings and Improvements		1,082,583
Land Held for Development		1,714
Development and Construction in Progress		161,688
Total		1,353,411
Accumulated Depreciation		$ 446,792
Year(s) built / renovated		1965/1993/2002
Depreciable Lives (Years)	[2]	(1)
Embarcadero Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Embarcadero Center
Type		Office
Location		San Francisco, CA
Encumbrances		$ 348,886
Original Land		179,697
Original Building		847,410
Costs Capitalized Subsequent to Acquisition		332,276
Land and improvements		195,987
Buildings and Improvements		1,163,396
Land Held for Development		0
Development and Construction in Progress		0
Total		1,359,383
Accumulated Depreciation		$ 542,103
Year(s) built / renovated		1970/1989
Depreciable Lives (Years)	[2]	(1)
399 Park Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		399 Park Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		339,200
Original Building		700,358
Costs Capitalized Subsequent to Acquisition		110,972
Land and improvements		354,107
Buildings and Improvements		796,423
Land Held for Development		0
Development and Construction in Progress		0
Total		1,150,530
Accumulated Depreciation		$ 265,266
Year(s) built / renovated		1,961
Depreciable Lives (Years)	[2]	(1)
200 Clarendon Street and Garage (formerly The John Hancock Tower and Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		200 Clarendon Street and Garage (formerly the John Hancock Tower and Garage)
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		219,543
Original Building		667,884
Costs Capitalized Subsequent to Acquisition		112,229
Land and improvements		219,616
Buildings and Improvements		776,755
Land Held for Development		3,285
Development and Construction in Progress		0
Total		999,656
Accumulated Depreciation		$ 128,815
Year(s) built / renovated		1,976
Depreciable Lives (Years)	[2]	(1)
601 Lexington Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		601 Lexington Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 699,061
Original Land		241,600
Original Building		494,782
Costs Capitalized Subsequent to Acquisition		231,812
Land and improvements		289,639
Buildings and Improvements		677,238
Land Held for Development		1,317
Development and Construction in Progress		0
Total		968,194
Accumulated Depreciation		$ 250,128
Year(s) built / renovated		1977/1997
Depreciable Lives (Years)	[2]	(1)
250 West 55th Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		250 West 55th Street
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		285,263
Original Building		603,167
Costs Capitalized Subsequent to Acquisition		16,488
Land and improvements		285,263
Buildings and Improvements		619,655
Land Held for Development		0
Development and Construction in Progress		0
Total		904,918
Accumulated Depreciation		$ 28,349
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[2]	(1)
Carnegie Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Carnegie Center
Type		Office
Location		Princeton, NJ
Encumbrances		$ 0
Original Land		105,107
Original Building		377,259
Costs Capitalized Subsequent to Acquisition		128,069
Land and improvements		103,064
Buildings and Improvements		464,086
Land Held for Development		2,475
Development and Construction in Progress		40,810
Total		610,435
Accumulated Depreciation		$ 198,387
Year(s) built / renovated		1983-1999
Depreciable Lives (Years)	[2]	(1)
Times Square Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Times Square Tower
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		165,413
Original Building		380,438
Costs Capitalized Subsequent to Acquisition		84,722
Land and improvements		169,193
Buildings and Improvements		461,380
Land Held for Development		0
Development and Construction in Progress		0
Total		630,573
Accumulated Depreciation		$ 164,767
Year(s) built / renovated		2,004
Depreciable Lives (Years)	[2]	(1)
100 Federal Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		100 Federal Street
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		131,067
Original Building		435,954
Costs Capitalized Subsequent to Acquisition		15,555
Land and improvements		131,067
Buildings and Improvements		450,933
Land Held for Development		576
Development and Construction in Progress		0
Total		582,576
Accumulated Depreciation		$ 60,125
Year(s) built / renovated		1971-1975
Depreciable Lives (Years)	[2]	(1)
Atlantic Wharf
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Atlantic Wharf
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		63,988
Original Building		454,537
Costs Capitalized Subsequent to Acquisition		16,376
Land and improvements		63,988
Buildings and Improvements		470,913
Land Held for Development		0
Development and Construction in Progress		0
Total		534,901
Accumulated Depreciation		$ 70,552
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[2]	(1)
510 Madison Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		510 Madison Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		103,000
Original Building		253,665
Costs Capitalized Subsequent to Acquisition		19,575
Land and improvements		103,000
Buildings and Improvements		273,240
Land Held for Development		0
Development and Construction in Progress		0
Total		376,240
Accumulated Depreciation		$ 34,640
Year(s) built / renovated		2,012
Depreciable Lives (Years)	[2]	(1)
Fountain Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Fountain Square
Type		Office
Location		Reston, VA
Encumbrances		$ 213,499
Original Land		56,853
Original Building		306,298
Costs Capitalized Subsequent to Acquisition		12,459
Land and improvements		56,853
Buildings and Improvements		318,757
Land Held for Development		0
Development and Construction in Progress		0
Total		375,610
Accumulated Depreciation		$ 39,508
Year(s) built / renovated		1986-1990
Depreciable Lives (Years)	[2]	(1)
599 Lexington Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		599 Lexington Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 750,000
Original Land		81,040
Original Building		100,507
Costs Capitalized Subsequent to Acquisition		149,551
Land and improvements		87,852
Buildings and Improvements		243,246
Land Held for Development		0
Development and Construction in Progress		0
Total		331,098
Accumulated Depreciation		$ 160,354
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[2]	(1)
680 Folsom Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		680 Folsom Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		72,545
Original Building		219,766
Costs Capitalized Subsequent to Acquisition		7,348
Land and improvements		72,545
Buildings and Improvements		227,114
Land Held for Development		0
Development and Construction in Progress		0
Total		299,659
Accumulated Depreciation		$ 13,091
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[2]	(1)
South of Market and Democracy Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		South of Market and Democracy Tower
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		13,603
Original Building		237,479
Costs Capitalized Subsequent to Acquisition		11,977
Land and improvements		13,687
Buildings and Improvements		249,372
Land Held for Development		0
Development and Construction in Progress		0
Total		263,059
Accumulated Depreciation		$ 70,437
Year(s) built / renovated		2008-2009
Depreciable Lives (Years)	[2]	(1)
Bay Colony Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Bay Colony Corporate Center
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		18,789
Original Building		148,451
Costs Capitalized Subsequent to Acquisition		65,997
Land and improvements		18,789
Buildings and Improvements		214,448
Land Held for Development		0
Development and Construction in Progress		0
Total		233,237
Accumulated Depreciation		$ 40,812
Year(s) built / renovated		1985-1989
Depreciable Lives (Years)	[2]	(1)
Gateway Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Gateway Center
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		28,255
Original Building		139,245
Costs Capitalized Subsequent to Acquisition		54,027
Land and improvements		30,627
Buildings and Improvements		190,900
Land Held for Development		0
Development and Construction in Progress		0
Total		221,527
Accumulated Depreciation		$ 94,083
Year(s) built / renovated		1984/1986/2002
Depreciable Lives (Years)	[2]	(1)
535 Mission Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		535 Mission Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		40,933
Original Building		148,378
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		40,933
Buildings and Improvements		148,378
Land Held for Development		0
Development and Construction in Progress		0
Total		189,311
Accumulated Depreciation		$ 3,221
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[2]	(1)
2200 Pennsylvania Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2200 Pennsylvania Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		0
Original Building		183,541
Costs Capitalized Subsequent to Acquisition		5,230
Land and improvements		0
Buildings and Improvements		188,771
Land Held for Development		0
Development and Construction in Progress		0
Total		188,771
Accumulated Depreciation		$ 33,039
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[2]	(1)
Mountain View Research Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Mountain View Research Park
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		95,066
Original Building		68,373
Costs Capitalized Subsequent to Acquisition		5,581
Land and improvements		95,066
Buildings and Improvements		73,954
Land Held for Development		0
Development and Construction in Progress		0
Total		169,020
Accumulated Depreciation		$ 9,581
Year(s) built / renovated		1977-1981/2007-2013
Depreciable Lives (Years)	[2]	(1)
Reservoir Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reservoir Place
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		18,605
Original Building		92,619
Costs Capitalized Subsequent to Acquisition		46,547
Land and improvements		20,118
Buildings and Improvements		128,975
Land Held for Development		0
Development and Construction in Progress		8,678
Total		157,771
Accumulated Depreciation		$ 57,706
Year(s) built / renovated		1955/1987
Depreciable Lives (Years)	[2]	(1)
Kingstowne Towne Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kingstowne Towne Center
Type		Office
Location		Alexandria, VA
Encumbrances		$ 0
Original Land		18,021
Original Building		109,038
Costs Capitalized Subsequent to Acquisition		1,276
Land and improvements		18,062
Buildings and Improvements		110,273
Land Held for Development		0
Development and Construction in Progress		0
Total		128,335
Accumulated Depreciation		$ 33,374
Year(s) built / renovated		2003-2006
Depreciable Lives (Years)	[2]	(1)
1333 New Hampshire Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		1333 New Hampshire Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		34,032
Original Building		85,660
Costs Capitalized Subsequent to Acquisition		10,841
Land and improvements		35,382
Buildings and Improvements		95,151
Land Held for Development		0
Development and Construction in Progress		0
Total		130,533
Accumulated Depreciation		$ 35,457
Year(s) built / renovated		1,996
Depreciable Lives (Years)	[2]	(1)
1330 Connecticut Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		1330 Connecticut Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		25,982
Original Building		82,311
Costs Capitalized Subsequent to Acquisition		19,098
Land and improvements		27,135
Buildings and Improvements		100,256
Land Held for Development		0
Development and Construction in Progress		0
Total		127,391
Accumulated Depreciation		$ 45,063
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
Weston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Weston Corporate Center
Type		Office
Location		Weston, MA
Encumbrances		$ 0
Original Land		25,753
Original Building		92,312
Costs Capitalized Subsequent to Acquisition		(123)
Land and improvements		25,854
Buildings and Improvements		92,088
Land Held for Development		0
Development and Construction in Progress		0
Total		117,942
Accumulated Depreciation		$ 17,023
Year(s) built / renovated		2,010
Depreciable Lives (Years)	[2]	(1)
Capital Gallery
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Capital Gallery
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		4,725
Original Building		29,565
Costs Capitalized Subsequent to Acquisition		88,569
Land and improvements		8,662
Buildings and Improvements		114,197
Land Held for Development		0
Development and Construction in Progress		0
Total		122,859
Accumulated Depreciation		$ 57,489
Year(s) built / renovated		1981/2006
Depreciable Lives (Years)	[2]	(1)
One Freedom Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		One Freedom Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		9,929
Original Building		84,504
Costs Capitalized Subsequent to Acquisition		19,613
Land and improvements		11,293
Buildings and Improvements		102,753
Land Held for Development		0
Development and Construction in Progress		0
Total		114,046
Accumulated Depreciation		$ 41,106
Year(s) built / renovated		2,000
Depreciable Lives (Years)	[2]	(1)
Two Freedom Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Two Freedom Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		13,930
Original Building		77,739
Costs Capitalized Subsequent to Acquisition		21,374
Land and improvements		15,420
Buildings and Improvements		97,623
Land Held for Development		0
Development and Construction in Progress		0
Total		113,043
Accumulated Depreciation		$ 41,164
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
415 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		415 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		3,457
Original Building		97,136
Costs Capitalized Subsequent to Acquisition		2,986
Land and improvements		4,125
Buildings and Improvements		99,454
Land Held for Development		0
Development and Construction in Progress		0
Total		103,579
Accumulated Depreciation		$ 59,405
Year(s) built / renovated		2,006
Depreciable Lives (Years)	[2]	(1)
355 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		355 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		18,863
Original Building		53,346
Costs Capitalized Subsequent to Acquisition		28,822
Land and improvements		21,173
Buildings and Improvements		79,858
Land Held for Development		0
Development and Construction in Progress		0
Total		101,031
Accumulated Depreciation		$ 23,372
Year(s) built / renovated		1981/1996/2013
Depreciable Lives (Years)	[2]	(1)
One and Two Reston Overlook
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		One and Two Reston Overlook
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		16,456
Original Building		66,192
Costs Capitalized Subsequent to Acquisition		22,385
Land and improvements		16,179
Buildings and Improvements		88,854
Land Held for Development		0
Development and Construction in Progress		0
Total		105,033
Accumulated Depreciation		$ 37,165
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[2]	(1)
Discovery Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Discovery Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		11,198
Original Building		71,782
Costs Capitalized Subsequent to Acquisition		21,234
Land and improvements		12,533
Buildings and Improvements		91,681
Land Held for Development		0
Development and Construction in Progress		0
Total		104,214
Accumulated Depreciation		$ 35,835
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
140 Kendrick Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		140 Kendrick Street
Type		Office
Location		Needham, MA
Encumbrances		$ 0
Original Land		18,095
Original Building		66,905
Costs Capitalized Subsequent to Acquisition		15,075
Land and improvements		19,092
Buildings and Improvements		80,983
Land Held for Development		0
Development and Construction in Progress		0
Total		100,075
Accumulated Depreciation		$ 23,191
Year(s) built / renovated		2,000
Depreciable Lives (Years)	[2]	(1)
90 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		90 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		19,104
Original Building		52,078
Costs Capitalized Subsequent to Acquisition		17,386
Land and improvements		20,785
Buildings and Improvements		67,783
Land Held for Development		0
Development and Construction in Progress		0
Total		88,568
Accumulated Depreciation		$ 14,394
Year(s) built / renovated		1983/1998/2013
Depreciable Lives (Years)	[2]	(1)
230 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		230 CityPoint
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		13,189
Original Building		49,823
Costs Capitalized Subsequent to Acquisition		18,800
Land and improvements		13,593
Buildings and Improvements		68,219
Land Held for Development		0
Development and Construction in Progress		0
Total		81,812
Accumulated Depreciation		$ 20,265
Year(s) built / renovated		1,992
Depreciable Lives (Years)	[2]	(1)
77 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		77 CityPoint
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		13,847
Original Building		60,383
Costs Capitalized Subsequent to Acquisition		5,605
Land and improvements		13,873
Buildings and Improvements		65,962
Land Held for Development		0
Development and Construction in Progress		0
Total		79,835
Accumulated Depreciation		$ 18,930
Year(s) built / renovated		2,008
Depreciable Lives (Years)	[2]	(1)
Waltham Weston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Waltham Weston Corporate Center
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		10,385
Original Building		60,694
Costs Capitalized Subsequent to Acquisition		8,907
Land and improvements		11,097
Buildings and Improvements		68,889
Land Held for Development		0
Development and Construction in Progress		0
Total		79,986
Accumulated Depreciation		$ 24,699
Year(s) built / renovated		2,003
Depreciable Lives (Years)	[2]	(1)
North First Business Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		North First Business Park
Type		Office
Location		San Jose, CA
Encumbrances		$ 0
Original Land		58,402
Original Building		13,069
Costs Capitalized Subsequent to Acquisition		4,028
Land and improvements		23,377
Buildings and Improvements		16,214
Land Held for Development		35,908
Development and Construction in Progress		0
Total		75,499
Accumulated Depreciation		$ 14,139
Year(s) built / renovated		1,981
Depreciable Lives (Years)	[2]	(1)
300 Binney Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		300 Binney Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		18,080
Original Building		51,262
Costs Capitalized Subsequent to Acquisition		140
Land and improvements		18,080
Buildings and Improvements		51,402
Land Held for Development		0
Development and Construction in Progress		0
Total		69,482
Accumulated Depreciation		$ 4,375
Year(s) built / renovated		2,013
Depreciable Lives (Years)	[2]	(1)
2440 West El Camino Real
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2440 West El Camino Real
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		16,741
Original Building		51,285
Costs Capitalized Subsequent to Acquisition		1,422
Land and improvements		16,741
Buildings and Improvements		52,707
Land Held for Development		0
Development and Construction in Progress		0
Total		69,448
Accumulated Depreciation		$ 8,185
Year(s) built / renovated		1987/2003
Depreciable Lives (Years)	[2]	(1)
Wisconsin Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Wisconsin Place
Type		Office
Location		Chevy Chase, MD
Encumbrances		$ 0
Original Land		0
Original Building		53,349
Costs Capitalized Subsequent to Acquisition		12,787
Land and improvements		0
Buildings and Improvements		66,136
Land Held for Development		0
Development and Construction in Progress		0
Total		66,136
Accumulated Depreciation		$ 18,272
Year(s) built / renovated		2,009
Depreciable Lives (Years)	[2]	(1)
Reston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Corporate Center
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		9,135
Original Building		50,857
Costs Capitalized Subsequent to Acquisition		6,464
Land and improvements		10,148
Buildings and Improvements		56,308
Land Held for Development		0
Development and Construction in Progress		0
Total		66,456
Accumulated Depreciation		$ 23,962
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
New Dominion Technology Park, Bldg. Two
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		New Dominion Technology Park, Bldg. Two
Type		Office
Location		Herndon, VA
Encumbrances		$ 0
Original Land		5,584
Original Building		51,868
Costs Capitalized Subsequent to Acquisition		3,911
Land and improvements		6,510
Buildings and Improvements		54,853
Land Held for Development		0
Development and Construction in Progress		0
Total		61,363
Accumulated Depreciation		$ 20,110
Year(s) built / renovated		2,004
Depreciable Lives (Years)	[2]	(1)
Sumner Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Sumner Square
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		624
Original Building		28,745
Costs Capitalized Subsequent to Acquisition		26,196
Land and improvements		1,478
Buildings and Improvements		54,087
Land Held for Development		0
Development and Construction in Progress		0
Total		55,565
Accumulated Depreciation		$ 26,923
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
200 West Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		200 West Street
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		16,148
Original Building		24,983
Costs Capitalized Subsequent to Acquisition		10,102
Land and improvements		16,813
Buildings and Improvements		34,420
Land Held for Development		0
Development and Construction in Progress		0
Total		51,233
Accumulated Depreciation		$ 18,034
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[2]	(1)
New Dominion Technology Park, Bldg. One
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		New Dominion Technology Park, Bldg. One
Type		Office
Location		Herndon, VA
Encumbrances		$ 38,494
Original Land		3,880
Original Building		43,227
Costs Capitalized Subsequent to Acquisition		3,883
Land and improvements		4,583
Buildings and Improvements		46,407
Land Held for Development		0
Development and Construction in Progress		0
Total		50,990
Accumulated Depreciation		$ 22,760
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
191 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		191 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		2,850
Original Building		27,166
Costs Capitalized Subsequent to Acquisition		18,610
Land and improvements		3,151
Buildings and Improvements		45,475
Land Held for Development		0
Development and Construction in Progress		0
Total		48,626
Accumulated Depreciation		$ 32,535
Year(s) built / renovated		1971/1995
Depreciable Lives (Years)	[2]	(1)
University Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		University Place
Type		Office
Location		Cambridge, MA
Encumbrances		$ 10,788
Original Land		0
Original Building		37,091
Costs Capitalized Subsequent to Acquisition		9,483
Land and improvements		390
Buildings and Improvements		46,184
Land Held for Development		0
Development and Construction in Progress		0
Total		46,574
Accumulated Depreciation		$ 23,635
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
255 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		255 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		134
Original Building		25,110
Costs Capitalized Subsequent to Acquisition		18,559
Land and improvements		548
Buildings and Improvements		43,255
Land Held for Development		0
Development and Construction in Progress		0
Total		43,803
Accumulated Depreciation		$ 27,153
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[2]	(1)
Quorum Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2600 Tower Oaks Boulevard
Type		Office
Location		Rockville, MD
Encumbrances		$ 0
Original Land		4,243
Original Building		31,125
Costs Capitalized Subsequent to Acquisition		8,656
Land and improvements		4,785
Buildings and Improvements		39,239
Land Held for Development		0
Development and Construction in Progress		0
Total		44,024
Accumulated Depreciation		$ 18,386
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
Quorum Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Quorum Office Park
Type		Office
Location		Chelmsford, MA
Encumbrances		$ 0
Original Land		3,750
Original Building		32,454
Costs Capitalized Subsequent to Acquisition		5,814
Land and improvements		5,187
Buildings and Improvements		36,831
Land Held for Development		0
Development and Construction in Progress		0
Total		42,018
Accumulated Depreciation		$ 14,671
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
150 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		150 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		850
Original Building		25,042
Costs Capitalized Subsequent to Acquisition		8,623
Land and improvements		1,323
Buildings and Improvements		33,192
Land Held for Development		0
Development and Construction in Progress		0
Total		34,515
Accumulated Depreciation		$ 14,073
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[2]	(1)
500 E Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		500 E Street
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		109
Original Building		22,420
Costs Capitalized Subsequent to Acquisition		13,144
Land and improvements		2,379
Buildings and Improvements		33,294
Land Held for Development		0
Development and Construction in Progress		0
Total		35,673
Accumulated Depreciation		$ 22,616
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[2]	(1)
325 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		325 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		174
Original Building		12,200
Costs Capitalized Subsequent to Acquisition		12,368
Land and improvements		965
Buildings and Improvements		23,777
Land Held for Development		0
Development and Construction in Progress		0
Total		24,742
Accumulated Depreciation		$ 11,339
Year(s) built / renovated		1987/2013
Depreciable Lives (Years)	[2]	(1)
105 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		105 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,299
Original Building		12,943
Costs Capitalized Subsequent to Acquisition		7,177
Land and improvements		2,395
Buildings and Improvements		19,024
Land Held for Development		0
Development and Construction in Progress		0
Total		21,419
Accumulated Depreciation		$ 12,556
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[2]	(1)
40 Shattuck Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		40 Shattuck Road
Type		Office
Location		Andover, MA
Encumbrances		$ 0
Original Land		709
Original Building		14,740
Costs Capitalized Subsequent to Acquisition		3,184
Land and improvements		893
Buildings and Improvements		17,740
Land Held for Development		0
Development and Construction in Progress		0
Total		18,633
Accumulated Depreciation		$ 6,846
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[2]	(1)
Lexington Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Lexington Office Park
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		998
Original Building		1,426
Costs Capitalized Subsequent to Acquisition		16,099
Land and improvements		1,264
Buildings and Improvements		17,259
Land Held for Development		0
Development and Construction in Progress		0
Total		18,523
Accumulated Depreciation		$ 11,730
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[2]	(1)
201 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		201 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		2,849
Original Building		15,303
Costs Capitalized Subsequent to Acquisition		(154)
Land and improvements		3,124
Buildings and Improvements		14,874
Land Held for Development		0
Development and Construction in Progress		0
Total		17,998
Accumulated Depreciation		$ 6,987
Year(s) built / renovated		1,997
Depreciable Lives (Years)	[2]	(1)
The Point (formerly 99 Third Avenue Retail)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Point (formerly 99 Third Avenue Retail)
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		6,395
Original Building		10,040
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		6,395
Buildings and Improvements		10,040
Land Held for Development		0
Development and Construction in Progress		0
Total		16,435
Accumulated Depreciation		$ 76
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[2]	(1)
91 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		91 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		784
Original Building		6,464
Costs Capitalized Subsequent to Acquisition		8,192
Land and improvements		941
Buildings and Improvements		14,499
Land Held for Development		0
Development and Construction in Progress		0
Total		15,440
Accumulated Depreciation		$ 8,525
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
92-100 Hayden Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		92-100 Hayden Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		594
Original Building		6,748
Costs Capitalized Subsequent to Acquisition		8,034
Land and improvements		802
Buildings and Improvements		14,574
Land Held for Development		0
Development and Construction in Progress		0
Total		15,376
Accumulated Depreciation		$ 11,412
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
690 Folsom Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		690 Folsom Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		3,219
Original Building		11,038
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		3,219
Buildings and Improvements		11,038
Land Held for Development		0
Development and Construction in Progress		0
Total		14,257
Accumulated Depreciation		$ 334
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[2]	(1)
181 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		181 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		1,066
Original Building		9,520
Costs Capitalized Subsequent to Acquisition		1,993
Land and improvements		1,160
Buildings and Improvements		11,419
Land Held for Development		0
Development and Construction in Progress		0
Total		12,579
Accumulated Depreciation		$ 4,580
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[2]	(1)
33 Hayden Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		33 Hayden Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		266
Original Building		3,234
Costs Capitalized Subsequent to Acquisition		8,787
Land and improvements		425
Buildings and Improvements		11,862
Land Held for Development		0
Development and Construction in Progress		0
Total		12,287
Accumulated Depreciation		$ 6,586
Year(s) built / renovated		1,979
Depreciable Lives (Years)	[2]	(1)
195 West Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		195 West Street
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		1,611
Original Building		6,652
Costs Capitalized Subsequent to Acquisition		4,340
Land and improvements		1,858
Buildings and Improvements		10,745
Land Held for Development		0
Development and Construction in Progress		0
Total		12,603
Accumulated Depreciation		$ 7,071
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[2]	(1)
145 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		145 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		121
Original Building		5,535
Costs Capitalized Subsequent to Acquisition		5,305
Land and improvements		324
Buildings and Improvements		10,637
Land Held for Development		0
Development and Construction in Progress		0
Total		10,961
Accumulated Depreciation		$ 7,864
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
7501 Boston Boulevard, Building Seven
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7501 Boston Boulevard, Building Seven
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		665
Original Building		9,273
Costs Capitalized Subsequent to Acquisition		520
Land and improvements		791
Buildings and Improvements		9,667
Land Held for Development		0
Development and Construction in Progress		0
Total		10,458
Accumulated Depreciation		$ 4,355
Year(s) built / renovated		1,997
Depreciable Lives (Years)	[2]	(1)
7435 Boston Boulevard, Building One
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7435 Boston Boulevard, Building One
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		392
Original Building		3,822
Costs Capitalized Subsequent to Acquisition		4,218
Land and improvements		659
Buildings and Improvements		7,773
Land Held for Development		0
Development and Construction in Progress		0
Total		8,432
Accumulated Depreciation		$ 6,052
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[2]	(1)
250 Binney Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		250 Binney Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		110
Original Building		4,483
Costs Capitalized Subsequent to Acquisition		3,593
Land and improvements		273
Buildings and Improvements		7,913
Land Held for Development		0
Development and Construction in Progress		0
Total		8,186
Accumulated Depreciation		$ 4,303
Year(s) built / renovated		1,983
Depreciable Lives (Years)	[2]	(1)
7450 Boston Boulevard, Building Three
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7450 Boston Boulevard, Building Three
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		1,165
Original Building		4,681
Costs Capitalized Subsequent to Acquisition		1,880
Land and improvements		1,430
Buildings and Improvements		6,296
Land Held for Development		0
Development and Construction in Progress		0
Total		7,726
Accumulated Depreciation		$ 3,226
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[2]	(1)
453 Ravendale Drive
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		453 Ravendale Drive
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		5,477
Original Building		1,090
Costs Capitalized Subsequent to Acquisition		235
Land and improvements		5,479
Buildings and Improvements		1,323
Land Held for Development		0
Development and Construction in Progress		0
Total		6,802
Accumulated Depreciation		$ 265
Year(s) built / renovated		1,977
Depreciable Lives (Years)	[2]	(1)
8000 Grainger Court, Building Five
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		8000 Grainger Court, Building Five
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		366
Original Building		4,282
Costs Capitalized Subsequent to Acquisition		2,684
Land and improvements		601
Buildings and Improvements		6,731
Land Held for Development		0
Development and Construction in Progress		0
Total		7,332
Accumulated Depreciation		$ 5,336
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
7500 Boston Boulevard, Building Six
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7500 Boston Boulevard, Building Six
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		138
Original Building		3,749
Costs Capitalized Subsequent to Acquisition		2,617
Land and improvements		406
Buildings and Improvements		6,098
Land Held for Development		0
Development and Construction in Progress		0
Total		6,504
Accumulated Depreciation		$ 4,499
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[2]	(1)
7300 Boston Boulevard, Building Thirteen
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7300 Boston Boulevard, Building Thirteen
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		608
Original Building		4,773
Costs Capitalized Subsequent to Acquisition		709
Land and improvements		661
Buildings and Improvements		5,429
Land Held for Development		0
Development and Construction in Progress		0
Total		6,090
Accumulated Depreciation		$ 4,626
Year(s) built / renovated		2,002
Depreciable Lives (Years)	[2]	(1)
7601 Boston Boulevard, Building Eight
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7601 Boston Boulevard, Building Eight
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		200
Original Building		878
Costs Capitalized Subsequent to Acquisition		4,924
Land and improvements		551
Buildings and Improvements		5,451
Land Held for Development		0
Development and Construction in Progress		0
Total		6,002
Accumulated Depreciation		$ 3,849
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[2]	(1)
8000 Corporate Court, Building Eleven
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		8000 Corporate Court, Building Eleven
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		136
Original Building		3,071
Costs Capitalized Subsequent to Acquisition		1,615
Land and improvements		775
Buildings and Improvements		4,047
Land Held for Development		0
Development and Construction in Progress		0
Total		4,822
Accumulated Depreciation		$ 2,639
Year(s) built / renovated		1,989
Depreciable Lives (Years)	[2]	(1)
7375 Boston Boulevard, Building Ten
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7375 Boston Boulevard, Building Ten
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		23
Original Building		2,685
Costs Capitalized Subsequent to Acquisition		1,003
Land and improvements		93
Buildings and Improvements		3,618
Land Held for Development		0
Development and Construction in Progress		0
Total		3,711
Accumulated Depreciation		$ 2,464
Year(s) built / renovated		1,988
Depreciable Lives (Years)	[2]	(1)
7374 Boston Boulevard, Building Four
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7374 Boston Boulevard, Building Four
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		241
Original Building		1,605
Costs Capitalized Subsequent to Acquisition		1,735
Land and improvements		398
Buildings and Improvements		3,183
Land Held for Development		0
Development and Construction in Progress		0
Total		3,581
Accumulated Depreciation		$ 2,345
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
7451 Boston Boulevard, Building Two
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7451 Boston Boulevard, Building Two
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		249
Original Building		1,542
Costs Capitalized Subsequent to Acquisition		1,661
Land and improvements		613
Buildings and Improvements		2,839
Land Held for Development		0
Development and Construction in Progress		0
Total		3,452
Accumulated Depreciation		$ 2,233
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[2]	(1)
32 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		32 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		168
Original Building		1,943
Costs Capitalized Subsequent to Acquisition		1,193
Land and improvements		314
Buildings and Improvements		2,990
Land Held for Development		0
Development and Construction in Progress		0
Total		3,304
Accumulated Depreciation		$ 1,786
Year(s) built / renovated		1968-1979/1987
Depreciable Lives (Years)	[2]	(1)
164 Lexington Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		164 Lexington Road
Type		Office
Location		Billerica, MA
Encumbrances		$ 0
Original Land		592
Original Building		1,370
Costs Capitalized Subsequent to Acquisition		319
Land and improvements		643
Buildings and Improvements		1,638
Land Held for Development		0
Development and Construction in Progress		0
Total		2,281
Accumulated Depreciation		$ 786
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[2]	(1)
17 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		17 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		26
Original Building		150
Costs Capitalized Subsequent to Acquisition		614
Land and improvements		65
Buildings and Improvements		725
Land Held for Development		0
Development and Construction in Progress		0
Total		790
Accumulated Depreciation		$ 323
Year(s) built / renovated		1,968
Depreciable Lives (Years)	[2]	(1)
The Avant at Reston Town Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Avant at Reston Town Center
Type		Residential
Location		Reston, VA
Encumbrances		$ 0
Original Land		20,350
Original Building		91,995
Costs Capitalized Subsequent to Acquisition		813
Land and improvements		20,350
Buildings and Improvements		92,808
Land Held for Development		0
Development and Construction in Progress		0
Total		113,158
Accumulated Depreciation		$ 4,833
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[2]	(1)
The Lofts at Atlantic Wharf
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Lofts at Atlantic Wharf
Type		Residential
Location		Boston, MA
Encumbrances		$ 0
Original Land		3,529
Original Building		54,891
Costs Capitalized Subsequent to Acquisition		1,579
Land and improvements		3,529
Buildings and Improvements		56,470
Land Held for Development		0
Development and Construction in Progress		0
Total		59,999
Accumulated Depreciation		$ 6,596
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[2]	(1)
Boston Marriott Cambridge
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Boston Marriott Cambridge
Type		Hotel
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		478
Original Building		37,918
Costs Capitalized Subsequent to Acquisition		35,665
Land and improvements		1,201
Buildings and Improvements		72,860
Land Held for Development		0
Development and Construction in Progress		0
Total		74,061
Accumulated Depreciation		$ 48,162
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[2]	(1)
Kendall Center Green Garage (formerly Cambridge Center East Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Green Garage (formerly Cambridge Center East Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		35,035
Costs Capitalized Subsequent to Acquisition		4,254
Land and improvements		103
Buildings and Improvements		39,186
Land Held for Development		0
Development and Construction in Progress		0
Total		39,289
Accumulated Depreciation		$ 8,610
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[2]	(1)
Kendall Center Yellow Garage (formerly Cambridge Center West Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Yellow Garage (formerly Cambridge Center West Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,256
Original Building		15,697
Costs Capitalized Subsequent to Acquisition		1,571
Land and improvements		1,434
Buildings and Improvements		17,090
Land Held for Development		0
Development and Construction in Progress		0
Total		18,524
Accumulated Depreciation		$ 4,269
Year(s) built / renovated		2,006
Depreciable Lives (Years)	[2]	(1)
Kendall Center Blue Garage (formerly Cambridge Center North Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Blue Garage (formerly Cambridge Center North Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,163
Original Building		11,633
Costs Capitalized Subsequent to Acquisition		2,770
Land and improvements		1,579
Buildings and Improvements		13,987
Land Held for Development		0
Development and Construction in Progress		0
Total		15,566
Accumulated Depreciation		$ 8,941
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[2]	(1)
Salesforce Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Salesforce Tower
Type		Development
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		429,767
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		429,767
Total		429,767
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
601 Massachusetts Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		601 Massachusetts Avenue
Type		Development
Location		Washington, DC
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		253,176
Land and improvements		95,322
Buildings and Improvements		140,791
Land Held for Development		0
Development and Construction in Progress		17,063
Total		253,176
Accumulated Depreciation		$ 1,531
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
10 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		10 CityPoint
Type		Development
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		70,389
Land and improvements		163
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		70,226
Total		70,389
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Reston Signature Site
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Signature Site
Type		Development
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		38,886
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		12,678
Development and Construction in Progress		26,208
Total		38,886
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Cambridge Residential / 88 Ames
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Cambridge Residential / 88 Ames
Type		Development
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		9,495
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		9,495
Total		9,495
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Springfield Metro Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Springfield Metro Center
Type		Land
Location		Springfield, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		34,870
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		34,870
Development and Construction in Progress		0
Total		34,870
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Tower Oaks Master Plan
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Tower Oaks Master Plan
Type		Land
Location		Rockville, MD
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		29,022
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		29,022
Development and Construction in Progress		0
Total		29,022
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Plaza at Almaden
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Plaza at Almaden
Type		Land
Location		San Jose, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		29,010
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		29,010
Development and Construction in Progress		0
Total		29,010
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
6601 & 6605 Springfield Center Drive
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		6601 & 6605 Springfield Center Drive
Type		Land
Location		Springfield, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		13,866
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		13,866
Development and Construction in Progress		0
Total		13,866
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
214 Third Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		214 Third Avenue
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		13,415
Land and improvements		0
Buildings and Improvements		132
Land Held for Development		13,283
Development and Construction in Progress		0
Total		13,415
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
103 Fourth Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		103 Fourth Avenue
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		11,927
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		11,927
Development and Construction in Progress		0
Total		11,927
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Reston Gateway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Gateway
Type		Land
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		10,294
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		10,294
Development and Construction in Progress		0
Total		10,294
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
20 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		20 CityPoint
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		10,258
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		10,258
Development and Construction in Progress		0
Total		10,258
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Reston Eastgate
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Eastgate
Type		Land
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		9,215
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		9,215
Development and Construction in Progress		0
Total		9,215
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Washingtonian North
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Washingtonian North
Type		Land
Location		Gaithersburg, MD
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		8,836
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		8,836
Development and Construction in Progress		0
Total		8,836
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Crane Meadow
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Crane Meadow
Type		Land
Location		Marlborough, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		8,727
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		8,727
Development and Construction in Progress		0
Total		8,727
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Broad Run Business Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Broad Run Business Park
Type		Land
Location		Loudoun County, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		6,399
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		6,399
Development and Construction in Progress		0
Total		6,399
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
North First Master Plan
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		North First Master Plan
Type		Land
Location		San Jose, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		2,999
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		2,999
Development and Construction in Progress		0
Total		2,999
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Fourth and Harrison (formerly 425 Fourth Street)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Fourth and Harrison (formerly 425 Fourth Street)
Type		Land
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		2,920
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		2,920
Development and Construction in Progress		0
Total		2,920
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Kendall Center Master Plan (formerly Cambridge Master Plan)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Master Plan (formerly Cambridge Master Plan)
Type		Land
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		1,403
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		1,403
Development and Construction in Progress		0
Total		1,403
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
30 Shattuck Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		30 Shattuck Road
Type		Land
Location		Andover, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		1,213
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		1,213
Development and Construction in Progress		0
Total		1,213
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	[3]	$ 3,438,714
Original Land		4,602,809
Original Building		11,248,289
Costs Capitalized Subsequent to Acquisition		3,180,191
Land and improvements		4,700,793
Buildings and Improvements		13,314,366
Land Held for Development		252,195
Development and Construction in Progress		763,935
Total		19,031,289
Accumulated Depreciation		3,826,862
Furniture, fixtures and equipment		29,852	$ 27,986
Furniture, fixtures and equipment accumulated depreciation		19,954
Real Estate Aggregate Cost For Tax Purposes		16,800,000
Real Estate Aggregate Accumulated Depreciation For Tax Purposes		$ 3,400,000
Real Estate and Accumulated Depreciation, Life Used for Depreciation		40 years
Unamortized balance of historical fair value adjustments		$ 80,200
Boston Properties Limited Partnership [Member] | 767 Fifth Avenue (the General Motors Building)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		767 Fifth Avenue (the General Motors Building)
Type		Office
Location		New York, NY
Encumbrances		$ 1,377,986
Original Land		1,796,252
Original Building		1,532,654
Costs Capitalized Subsequent to Acquisition		45,800
Land and improvements		1,796,252
Buildings and Improvements		1,578,454
Land Held for Development		0
Development and Construction in Progress		0
Total		3,374,706
Accumulated Depreciation		$ 128,488
Year(s) built / renovated		1,968
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Prudential Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Prudential Center
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		92,077
Original Building		734,594
Costs Capitalized Subsequent to Acquisition		466,370
Land and improvements		92,328
Buildings and Improvements		1,037,311
Land Held for Development		1,714
Development and Construction in Progress		161,688
Total		1,293,041
Accumulated Depreciation		$ 435,437
Year(s) built / renovated		1965/1993/2002
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Embarcadero Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Embarcadero Center
Type		Office
Location		San Francisco, CA
Encumbrances		$ 348,886
Original Land		179,697
Original Building		847,410
Costs Capitalized Subsequent to Acquisition		269,895
Land and improvements		180,420
Buildings and Improvements		1,116,582
Land Held for Development		0
Development and Construction in Progress		0
Total		1,297,002
Accumulated Depreciation		$ 530,307
Year(s) built / renovated		1970/1989
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 399 Park Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		399 Park Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		339,200
Original Building		700,358
Costs Capitalized Subsequent to Acquisition		51,364
Land and improvements		339,200
Buildings and Improvements		751,722
Land Held for Development		0
Development and Construction in Progress		0
Total		1,090,922
Accumulated Depreciation		$ 254,028
Year(s) built / renovated		1,961
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 200 Clarendon Street and Garage (formerly The John Hancock Tower and Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		200 Clarendon Street and Garage (formerly the John Hancock Tower and Garage)
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		219,543
Original Building		667,884
Costs Capitalized Subsequent to Acquisition		112,229
Land and improvements		219,616
Buildings and Improvements		776,755
Land Held for Development		3,285
Development and Construction in Progress		0
Total		999,656
Accumulated Depreciation		$ 128,815
Year(s) built / renovated		1,976
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 601 Lexington Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		601 Lexington Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 699,061
Original Land		241,600
Original Building		494,782
Costs Capitalized Subsequent to Acquisition		190,393
Land and improvements		279,281
Buildings and Improvements		646,177
Land Held for Development		1,317
Development and Construction in Progress		0
Total		926,775
Accumulated Depreciation		$ 242,358
Year(s) built / renovated		1977/1997
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 250 West 55th Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		250 West 55th Street
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		285,263
Original Building		603,167
Costs Capitalized Subsequent to Acquisition		16,488
Land and improvements		285,263
Buildings and Improvements		619,655
Land Held for Development		0
Development and Construction in Progress		0
Total		904,918
Accumulated Depreciation		$ 28,349
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Carnegie Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Carnegie Center
Type		Office
Location		Princeton, NJ
Encumbrances		$ 0
Original Land		105,107
Original Building		377,259
Costs Capitalized Subsequent to Acquisition		110,751
Land and improvements		98,733
Buildings and Improvements		451,099
Land Held for Development		2,475
Development and Construction in Progress		40,810
Total		593,117
Accumulated Depreciation		$ 195,128
Year(s) built / renovated		1983-1999
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Times Square Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Times Square Tower
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		165,413
Original Building		380,438
Costs Capitalized Subsequent to Acquisition		46,743
Land and improvements		159,694
Buildings and Improvements		432,900
Land Held for Development		0
Development and Construction in Progress		0
Total		592,594
Accumulated Depreciation		$ 157,622
Year(s) built / renovated		2,004
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 100 Federal Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		100 Federal Street
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		131,067
Original Building		435,954
Costs Capitalized Subsequent to Acquisition		15,555
Land and improvements		131,067
Buildings and Improvements		450,933
Land Held for Development		576
Development and Construction in Progress		0
Total		582,576
Accumulated Depreciation		$ 60,125
Year(s) built / renovated		1971-1975
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Atlantic Wharf
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Atlantic Wharf
Type		Office
Location		Boston, MA
Encumbrances		$ 0
Original Land		63,988
Original Building		454,537
Costs Capitalized Subsequent to Acquisition		16,376
Land and improvements		63,988
Buildings and Improvements		470,913
Land Held for Development		0
Development and Construction in Progress		0
Total		534,901
Accumulated Depreciation		$ 70,552
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 510 Madison Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		510 Madison Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 0
Original Land		103,000
Original Building		253,665
Costs Capitalized Subsequent to Acquisition		19,575
Land and improvements		103,000
Buildings and Improvements		273,240
Land Held for Development		0
Development and Construction in Progress		0
Total		376,240
Accumulated Depreciation		$ 34,640
Year(s) built / renovated		2,012
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Fountain Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Fountain Square
Type		Office
Location		Reston, VA
Encumbrances		$ 213,499
Original Land		56,853
Original Building		306,298
Costs Capitalized Subsequent to Acquisition		12,459
Land and improvements		56,853
Buildings and Improvements		318,757
Land Held for Development		0
Development and Construction in Progress		0
Total		375,610
Accumulated Depreciation		$ 39,508
Year(s) built / renovated		1986-1990
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 599 Lexington Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		599 Lexington Avenue
Type		Office
Location		New York, NY
Encumbrances		$ 750,000
Original Land		81,040
Original Building		100,507
Costs Capitalized Subsequent to Acquisition		122,309
Land and improvements		81,040
Buildings and Improvements		222,816
Land Held for Development		0
Development and Construction in Progress		0
Total		303,856
Accumulated Depreciation		$ 155,235
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 680 Folsom Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		680 Folsom Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		72,545
Original Building		219,766
Costs Capitalized Subsequent to Acquisition		7,348
Land and improvements		72,545
Buildings and Improvements		227,114
Land Held for Development		0
Development and Construction in Progress		0
Total		299,659
Accumulated Depreciation		$ 13,091
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | South of Market and Democracy Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		South of Market and Democracy Tower
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		13,603
Original Building		237,479
Costs Capitalized Subsequent to Acquisition		11,641
Land and improvements		13,603
Buildings and Improvements		249,120
Land Held for Development		0
Development and Construction in Progress		0
Total		262,723
Accumulated Depreciation		$ 70,389
Year(s) built / renovated		2008-2009
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Bay Colony Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Bay Colony Corporate Center
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		18,789
Original Building		148,451
Costs Capitalized Subsequent to Acquisition		65,997
Land and improvements		18,789
Buildings and Improvements		214,448
Land Held for Development		0
Development and Construction in Progress		0
Total		233,237
Accumulated Depreciation		$ 40,812
Year(s) built / renovated		1985-1989
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Gateway Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Gateway Center
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		28,255
Original Building		139,245
Costs Capitalized Subsequent to Acquisition		47,638
Land and improvements		29,029
Buildings and Improvements		186,109
Land Held for Development		0
Development and Construction in Progress		0
Total		215,138
Accumulated Depreciation		$ 92,882
Year(s) built / renovated		1984/1986/2002
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 535 Mission Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		535 Mission Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		40,933
Original Building		148,378
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		40,933
Buildings and Improvements		148,378
Land Held for Development		0
Development and Construction in Progress		0
Total		189,311
Accumulated Depreciation		$ 3,221
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 2200 Pennsylvania Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2200 Pennsylvania Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		0
Original Building		183,541
Costs Capitalized Subsequent to Acquisition		5,230
Land and improvements		0
Buildings and Improvements		188,771
Land Held for Development		0
Development and Construction in Progress		0
Total		188,771
Accumulated Depreciation		$ 33,039
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Mountain View Research Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Mountain View Research Park
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		95,066
Original Building		68,373
Costs Capitalized Subsequent to Acquisition		5,581
Land and improvements		95,066
Buildings and Improvements		73,954
Land Held for Development		0
Development and Construction in Progress		0
Total		169,020
Accumulated Depreciation		$ 9,581
Year(s) built / renovated		1977-1981/2007-2013
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Reservoir Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reservoir Place
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		18,605
Original Building		92,619
Costs Capitalized Subsequent to Acquisition		42,472
Land and improvements		19,099
Buildings and Improvements		125,919
Land Held for Development		0
Development and Construction in Progress		8,678
Total		153,696
Accumulated Depreciation		$ 56,939
Year(s) built / renovated		1955/1987
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Kingstowne Towne Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kingstowne Towne Center
Type		Office
Location		Alexandria, VA
Encumbrances		$ 0
Original Land		18,021
Original Building		109,038
Costs Capitalized Subsequent to Acquisition		1,112
Land and improvements		18,021
Buildings and Improvements		110,150
Land Held for Development		0
Development and Construction in Progress		0
Total		128,171
Accumulated Depreciation		$ 33,350
Year(s) built / renovated		2003-2006
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 1333 New Hampshire Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		1333 New Hampshire Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		34,032
Original Building		85,660
Costs Capitalized Subsequent to Acquisition		5,447
Land and improvements		34,032
Buildings and Improvements		91,107
Land Held for Development		0
Development and Construction in Progress		0
Total		125,139
Accumulated Depreciation		$ 34,441
Year(s) built / renovated		1,996
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 1330 Connecticut Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		1330 Connecticut Avenue
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		25,982
Original Building		82,311
Costs Capitalized Subsequent to Acquisition		14,485
Land and improvements		25,982
Buildings and Improvements		96,796
Land Held for Development		0
Development and Construction in Progress		0
Total		122,778
Accumulated Depreciation		$ 44,193
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Weston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Weston Corporate Center
Type		Office
Location		Weston, MA
Encumbrances		$ 0
Original Land		25,753
Original Building		92,312
Costs Capitalized Subsequent to Acquisition		(123)
Land and improvements		25,854
Buildings and Improvements		92,088
Land Held for Development		0
Development and Construction in Progress		0
Total		117,942
Accumulated Depreciation		$ 17,023
Year(s) built / renovated		2,010
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Capital Gallery
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Capital Gallery
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		4,725
Original Building		29,565
Costs Capitalized Subsequent to Acquisition		78,438
Land and improvements		6,128
Buildings and Improvements		106,600
Land Held for Development		0
Development and Construction in Progress		0
Total		112,728
Accumulated Depreciation		$ 55,581
Year(s) built / renovated		1981/2006
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | One Freedom Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		One Freedom Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		9,929
Original Building		84,504
Costs Capitalized Subsequent to Acquisition		13,976
Land and improvements		9,883
Buildings and Improvements		98,526
Land Held for Development		0
Development and Construction in Progress		0
Total		108,409
Accumulated Depreciation		$ 40,044
Year(s) built / renovated		2,000
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Two Freedom Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Two Freedom Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		13,930
Original Building		77,739
Costs Capitalized Subsequent to Acquisition		15,162
Land and improvements		13,866
Buildings and Improvements		92,965
Land Held for Development		0
Development and Construction in Progress		0
Total		106,831
Accumulated Depreciation		$ 39,996
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 415 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		415 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		3,457
Original Building		97,136
Costs Capitalized Subsequent to Acquisition		316
Land and improvements		3,457
Buildings and Improvements		97,452
Land Held for Development		0
Development and Construction in Progress		0
Total		100,909
Accumulated Depreciation		$ 58,907
Year(s) built / renovated		2,006
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 355 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		355 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		18,863
Original Building		53,346
Costs Capitalized Subsequent to Acquisition		28,524
Land and improvements		21,098
Buildings and Improvements		79,635
Land Held for Development		0
Development and Construction in Progress		0
Total		100,733
Accumulated Depreciation		$ 23,319
Year(s) built / renovated		1981/1996/2013
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | One and Two Reston Overlook
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		One and Two Reston Overlook
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		16,456
Original Building		66,192
Costs Capitalized Subsequent to Acquisition		17,967
Land and improvements		15,074
Buildings and Improvements		85,541
Land Held for Development		0
Development and Construction in Progress		0
Total		100,615
Accumulated Depreciation		$ 36,334
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Discovery Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Discovery Square
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		11,198
Original Building		71,782
Costs Capitalized Subsequent to Acquisition		15,689
Land and improvements		11,146
Buildings and Improvements		87,523
Land Held for Development		0
Development and Construction in Progress		0
Total		98,669
Accumulated Depreciation		$ 34,789
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 140 Kendrick Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		140 Kendrick Street
Type		Office
Location		Needham, MA
Encumbrances		$ 0
Original Land		18,095
Original Building		66,905
Costs Capitalized Subsequent to Acquisition		11,085
Land and improvements		18,095
Buildings and Improvements		77,990
Land Held for Development		0
Development and Construction in Progress		0
Total		96,085
Accumulated Depreciation		$ 22,441
Year(s) built / renovated		2,000
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 90 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		90 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		19,104
Original Building		52,078
Costs Capitalized Subsequent to Acquisition		17,207
Land and improvements		20,741
Buildings and Improvements		67,648
Land Held for Development		0
Development and Construction in Progress		0
Total		88,389
Accumulated Depreciation		$ 14,366
Year(s) built / renovated		1983/1998/2013
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 230 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		230 CityPoint
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		13,189
Original Building		49,823
Costs Capitalized Subsequent to Acquisition		17,183
Land and improvements		13,189
Buildings and Improvements		67,006
Land Held for Development		0
Development and Construction in Progress		0
Total		80,195
Accumulated Depreciation		$ 19,965
Year(s) built / renovated		1,992
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 77 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		77 CityPoint
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		13,847
Original Building		60,383
Costs Capitalized Subsequent to Acquisition		5,500
Land and improvements		13,847
Buildings and Improvements		65,883
Land Held for Development		0
Development and Construction in Progress		0
Total		79,730
Accumulated Depreciation		$ 18,914
Year(s) built / renovated		2,008
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Waltham Weston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Waltham Weston Corporate Center
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		10,385
Original Building		60,694
Costs Capitalized Subsequent to Acquisition		5,920
Land and improvements		10,350
Buildings and Improvements		66,649
Land Held for Development		0
Development and Construction in Progress		0
Total		76,999
Accumulated Depreciation		$ 24,136
Year(s) built / renovated		2,003
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | North First Business Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		North First Business Park
Type		Office
Location		San Jose, CA
Encumbrances		$ 0
Original Land		58,402
Original Building		13,069
Costs Capitalized Subsequent to Acquisition		4,005
Land and improvements		23,371
Buildings and Improvements		16,197
Land Held for Development		35,908
Development and Construction in Progress		0
Total		75,476
Accumulated Depreciation		$ 14,139
Year(s) built / renovated		1,981
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 300 Binney Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		300 Binney Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		18,080
Original Building		51,262
Costs Capitalized Subsequent to Acquisition		140
Land and improvements		18,080
Buildings and Improvements		51,402
Land Held for Development		0
Development and Construction in Progress		0
Total		69,482
Accumulated Depreciation		$ 4,375
Year(s) built / renovated		2,013
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 2440 West El Camino Real
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2440 West El Camino Real
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		16,741
Original Building		51,285
Costs Capitalized Subsequent to Acquisition		1,422
Land and improvements		16,741
Buildings and Improvements		52,707
Land Held for Development		0
Development and Construction in Progress		0
Total		69,448
Accumulated Depreciation		$ 8,185
Year(s) built / renovated		1987/2003
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Wisconsin Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Wisconsin Place
Type		Office
Location		Chevy Chase, MD
Encumbrances		$ 0
Original Land		0
Original Building		53,349
Costs Capitalized Subsequent to Acquisition		12,787
Land and improvements		0
Buildings and Improvements		66,136
Land Held for Development		0
Development and Construction in Progress		0
Total		66,136
Accumulated Depreciation		$ 18,272
Year(s) built / renovated		2,009
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Reston Corporate Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Corporate Center
Type		Office
Location		Reston, VA
Encumbrances		$ 0
Original Land		9,135
Original Building		50,857
Costs Capitalized Subsequent to Acquisition		3,853
Land and improvements		9,496
Buildings and Improvements		54,349
Land Held for Development		0
Development and Construction in Progress		0
Total		63,845
Accumulated Depreciation		$ 23,471
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | New Dominion Technology Park, Bldg. Two
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		New Dominion Technology Park, Bldg. Two
Type		Office
Location		Herndon, VA
Encumbrances		$ 0
Original Land		5,584
Original Building		51,868
Costs Capitalized Subsequent to Acquisition		166
Land and improvements		5,574
Buildings and Improvements		52,044
Land Held for Development		0
Development and Construction in Progress		0
Total		57,618
Accumulated Depreciation		$ 19,401
Year(s) built / renovated		2,004
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Sumner Square
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Sumner Square
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		624
Original Building		28,745
Costs Capitalized Subsequent to Acquisition		24,116
Land and improvements		958
Buildings and Improvements		52,527
Land Held for Development		0
Development and Construction in Progress		0
Total		53,485
Accumulated Depreciation		$ 26,534
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 200 West Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		200 West Street
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		16,148
Original Building		24,983
Costs Capitalized Subsequent to Acquisition		7,441
Land and improvements		16,148
Buildings and Improvements		32,424
Land Held for Development		0
Development and Construction in Progress		0
Total		48,572
Accumulated Depreciation		$ 17,532
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | New Dominion Technology Park, Bldg. One
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		New Dominion Technology Park, Bldg. One
Type		Office
Location		Herndon, VA
Encumbrances		$ 38,494
Original Land		3,880
Original Building		43,227
Costs Capitalized Subsequent to Acquisition		1,074
Land and improvements		3,880
Buildings and Improvements		44,301
Land Held for Development		0
Development and Construction in Progress		0
Total		48,181
Accumulated Depreciation		$ 22,230
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 191 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		191 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		2,850
Original Building		27,166
Costs Capitalized Subsequent to Acquisition		17,411
Land and improvements		2,850
Buildings and Improvements		44,577
Land Held for Development		0
Development and Construction in Progress		0
Total		47,427
Accumulated Depreciation		$ 32,307
Year(s) built / renovated		1971/1995
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | University Place
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		University Place
Type		Office
Location		Cambridge, MA
Encumbrances		$ 10,788
Original Land		0
Original Building		37,091
Costs Capitalized Subsequent to Acquisition		8,033
Land and improvements		27
Buildings and Improvements		45,097
Land Held for Development		0
Development and Construction in Progress		0
Total		45,124
Accumulated Depreciation		$ 23,365
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 255 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		255 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		134
Original Building		25,110
Costs Capitalized Subsequent to Acquisition		16,903
Land and improvements		134
Buildings and Improvements		42,013
Land Held for Development		0
Development and Construction in Progress		0
Total		42,147
Accumulated Depreciation		$ 26,843
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Quorum Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		2600 Tower Oaks Boulevard
Type		Office
Location		Rockville, MD
Encumbrances		$ 0
Original Land		4,243
Original Building		31,125
Costs Capitalized Subsequent to Acquisition		6,493
Land and improvements		4,244
Buildings and Improvements		37,617
Land Held for Development		0
Development and Construction in Progress		0
Total		41,861
Accumulated Depreciation		$ 17,977
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Quorum Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Quorum Office Park
Type		Office
Location		Chelmsford, MA
Encumbrances		$ 0
Original Land		3,750
Original Building		32,454
Costs Capitalized Subsequent to Acquisition		4,115
Land and improvements		4,762
Buildings and Improvements		35,557
Land Held for Development		0
Development and Construction in Progress		0
Total		40,319
Accumulated Depreciation		$ 14,352
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 150 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		150 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		850
Original Building		25,042
Costs Capitalized Subsequent to Acquisition		6,618
Land and improvements		822
Buildings and Improvements		31,688
Land Held for Development		0
Development and Construction in Progress		0
Total		32,510
Accumulated Depreciation		$ 13,693
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 500 E Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		500 E Street
Type		Office
Location		Washington, DC
Encumbrances		$ 0
Original Land		109
Original Building		22,420
Costs Capitalized Subsequent to Acquisition		9,904
Land and improvements		1,569
Buildings and Improvements		30,864
Land Held for Development		0
Development and Construction in Progress		0
Total		32,433
Accumulated Depreciation		$ 22,008
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 325 Main Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		325 Main Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		174
Original Building		12,200
Costs Capitalized Subsequent to Acquisition		11,597
Land and improvements		772
Buildings and Improvements		23,199
Land Held for Development		0
Development and Construction in Progress		0
Total		23,971
Accumulated Depreciation		$ 11,192
Year(s) built / renovated		1987/2013
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 105 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		105 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,299
Original Building		12,943
Costs Capitalized Subsequent to Acquisition		5,071
Land and improvements		1,868
Buildings and Improvements		17,445
Land Held for Development		0
Development and Construction in Progress		0
Total		19,313
Accumulated Depreciation		$ 12,158
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 40 Shattuck Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		40 Shattuck Road
Type		Office
Location		Andover, MA
Encumbrances		$ 0
Original Land		709
Original Building		14,740
Costs Capitalized Subsequent to Acquisition		2,448
Land and improvements		709
Buildings and Improvements		17,188
Land Held for Development		0
Development and Construction in Progress		0
Total		17,897
Accumulated Depreciation		$ 6,707
Year(s) built / renovated		2,001
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Lexington Office Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Lexington Office Park
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		998
Original Building		1,426
Costs Capitalized Subsequent to Acquisition		15,335
Land and improvements		1,073
Buildings and Improvements		16,686
Land Held for Development		0
Development and Construction in Progress		0
Total		17,759
Accumulated Depreciation		$ 11,589
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 201 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		201 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		2,849
Original Building		15,303
Costs Capitalized Subsequent to Acquisition		(1,253)
Land and improvements		2,849
Buildings and Improvements		14,050
Land Held for Development		0
Development and Construction in Progress		0
Total		16,899
Accumulated Depreciation		$ 6,779
Year(s) built / renovated		1,997
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | The Point (formerly 99 Third Avenue Retail)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Point (formerly 99 Third Avenue Retail)
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		6,395
Original Building		10,040
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		6,395
Buildings and Improvements		10,040
Land Held for Development		0
Development and Construction in Progress		0
Total		16,435
Accumulated Depreciation		$ 76
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 91 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		91 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		784
Original Building		6,464
Costs Capitalized Subsequent to Acquisition		7,565
Land and improvements		784
Buildings and Improvements		14,029
Land Held for Development		0
Development and Construction in Progress		0
Total		14,813
Accumulated Depreciation		$ 8,405
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 92-100 Hayden Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		92-100 Hayden Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		594
Original Building		6,748
Costs Capitalized Subsequent to Acquisition		7,305
Land and improvements		619
Buildings and Improvements		14,028
Land Held for Development		0
Development and Construction in Progress		0
Total		14,647
Accumulated Depreciation		$ 11,274
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 690 Folsom Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		690 Folsom Street
Type		Office
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		3,219
Original Building		11,038
Costs Capitalized Subsequent to Acquisition		0
Land and improvements		3,219
Buildings and Improvements		11,038
Land Held for Development		0
Development and Construction in Progress		0
Total		14,257
Accumulated Depreciation		$ 334
Year(s) built / renovated		2,015
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 181 Spring Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		181 Spring Street
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		1,066
Original Building		9,520
Costs Capitalized Subsequent to Acquisition		1,616
Land and improvements		1,066
Buildings and Improvements		11,136
Land Held for Development		0
Development and Construction in Progress		0
Total		12,202
Accumulated Depreciation		$ 4,509
Year(s) built / renovated		1,999
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 33 Hayden Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		33 Hayden Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		266
Original Building		3,234
Costs Capitalized Subsequent to Acquisition		8,150
Land and improvements		266
Buildings and Improvements		11,384
Land Held for Development		0
Development and Construction in Progress		0
Total		11,650
Accumulated Depreciation		$ 6,466
Year(s) built / renovated		1,979
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 195 West Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		195 West Street
Type		Office
Location		Waltham, MA
Encumbrances		$ 0
Original Land		1,611
Original Building		6,652
Costs Capitalized Subsequent to Acquisition		3,351
Land and improvements		1,611
Buildings and Improvements		10,003
Land Held for Development		0
Development and Construction in Progress		0
Total		11,614
Accumulated Depreciation		$ 6,882
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 145 Broadway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		145 Broadway
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		121
Original Building		5,535
Costs Capitalized Subsequent to Acquisition		4,492
Land and improvements		121
Buildings and Improvements		10,027
Land Held for Development		0
Development and Construction in Progress		0
Total		10,148
Accumulated Depreciation		$ 7,713
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7501 Boston Boulevard, Building Seven
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7501 Boston Boulevard, Building Seven
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		665
Original Building		9,273
Costs Capitalized Subsequent to Acquisition		15
Land and improvements		665
Buildings and Improvements		9,288
Land Held for Development		0
Development and Construction in Progress		0
Total		9,953
Accumulated Depreciation		$ 4,259
Year(s) built / renovated		1,997
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7435 Boston Boulevard, Building One
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7435 Boston Boulevard, Building One
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		392
Original Building		3,822
Costs Capitalized Subsequent to Acquisition		3,525
Land and improvements		486
Buildings and Improvements		7,253
Land Held for Development		0
Development and Construction in Progress		0
Total		7,739
Accumulated Depreciation		$ 5,922
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 250 Binney Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		250 Binney Street
Type		Office
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		110
Original Building		4,483
Costs Capitalized Subsequent to Acquisition		2,939
Land and improvements		110
Buildings and Improvements		7,422
Land Held for Development		0
Development and Construction in Progress		0
Total		7,532
Accumulated Depreciation		$ 4,183
Year(s) built / renovated		1,983
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7450 Boston Boulevard, Building Three
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7450 Boston Boulevard, Building Three
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		1,165
Original Building		4,681
Costs Capitalized Subsequent to Acquisition		1,466
Land and improvements		1,327
Buildings and Improvements		5,985
Land Held for Development		0
Development and Construction in Progress		0
Total		7,312
Accumulated Depreciation		$ 3,145
Year(s) built / renovated		1,987
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 453 Ravendale Drive
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		453 Ravendale Drive
Type		Office
Location		Mountain View, CA
Encumbrances		$ 0
Original Land		5,477
Original Building		1,090
Costs Capitalized Subsequent to Acquisition		233
Land and improvements		5,477
Buildings and Improvements		1,323
Land Held for Development		0
Development and Construction in Progress		0
Total		6,800
Accumulated Depreciation		$ 265
Year(s) built / renovated		1,977
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 8000 Grainger Court, Building Five
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		8000 Grainger Court, Building Five
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		366
Original Building		4,282
Costs Capitalized Subsequent to Acquisition		2,090
Land and improvements		453
Buildings and Improvements		6,285
Land Held for Development		0
Development and Construction in Progress		0
Total		6,738
Accumulated Depreciation		$ 5,225
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7500 Boston Boulevard, Building Six
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7500 Boston Boulevard, Building Six
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		138
Original Building		3,749
Costs Capitalized Subsequent to Acquisition		2,084
Land and improvements		273
Buildings and Improvements		5,698
Land Held for Development		0
Development and Construction in Progress		0
Total		5,971
Accumulated Depreciation		$ 4,399
Year(s) built / renovated		1,985
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7300 Boston Boulevard, Building Thirteen
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7300 Boston Boulevard, Building Thirteen
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		608
Original Building		4,773
Costs Capitalized Subsequent to Acquisition		497
Land and improvements		608
Buildings and Improvements		5,270
Land Held for Development		0
Development and Construction in Progress		0
Total		5,878
Accumulated Depreciation		$ 4,586
Year(s) built / renovated		2,002
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7601 Boston Boulevard, Building Eight
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7601 Boston Boulevard, Building Eight
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		200
Original Building		878
Costs Capitalized Subsequent to Acquisition		4,231
Land and improvements		378
Buildings and Improvements		4,931
Land Held for Development		0
Development and Construction in Progress		0
Total		5,309
Accumulated Depreciation		$ 3,719
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 8000 Corporate Court, Building Eleven
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		8000 Corporate Court, Building Eleven
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		136
Original Building		3,071
Costs Capitalized Subsequent to Acquisition		1,264
Land and improvements		687
Buildings and Improvements		3,784
Land Held for Development		0
Development and Construction in Progress		0
Total		4,471
Accumulated Depreciation		$ 2,570
Year(s) built / renovated		1,989
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7375 Boston Boulevard, Building Ten
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7375 Boston Boulevard, Building Ten
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		23
Original Building		2,685
Costs Capitalized Subsequent to Acquisition		822
Land and improvements		47
Buildings and Improvements		3,483
Land Held for Development		0
Development and Construction in Progress		0
Total		3,530
Accumulated Depreciation		$ 2,432
Year(s) built / renovated		1,988
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7374 Boston Boulevard, Building Four
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7374 Boston Boulevard, Building Four
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		241
Original Building		1,605
Costs Capitalized Subsequent to Acquisition		1,352
Land and improvements		303
Buildings and Improvements		2,895
Land Held for Development		0
Development and Construction in Progress		0
Total		3,198
Accumulated Depreciation		$ 2,275
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 7451 Boston Boulevard, Building Two
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		7451 Boston Boulevard, Building Two
Type		Office
Location		Springfield, VA
Encumbrances		$ 0
Original Land		249
Original Building		1,542
Costs Capitalized Subsequent to Acquisition		1,348
Land and improvements		535
Buildings and Improvements		2,604
Land Held for Development		0
Development and Construction in Progress		0
Total		3,139
Accumulated Depreciation		$ 2,173
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 32 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		32 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		168
Original Building		1,943
Costs Capitalized Subsequent to Acquisition		607
Land and improvements		168
Buildings and Improvements		2,550
Land Held for Development		0
Development and Construction in Progress		0
Total		2,718
Accumulated Depreciation		$ 1,674
Year(s) built / renovated		1968-1979/1987
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 164 Lexington Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		164 Lexington Road
Type		Office
Location		Billerica, MA
Encumbrances		$ 0
Original Land		592
Original Building		1,370
Costs Capitalized Subsequent to Acquisition		117
Land and improvements		592
Buildings and Improvements		1,487
Land Held for Development		0
Development and Construction in Progress		0
Total		2,079
Accumulated Depreciation		$ 745
Year(s) built / renovated		1,982
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | 17 Hartwell Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		17 Hartwell Avenue
Type		Office
Location		Lexington, MA
Encumbrances		$ 0
Original Land		26
Original Building		150
Costs Capitalized Subsequent to Acquisition		457
Land and improvements		26
Buildings and Improvements		607
Land Held for Development		0
Development and Construction in Progress		0
Total		633
Accumulated Depreciation		$ 293
Year(s) built / renovated		1,968
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | The Avant at Reston Town Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Avant at Reston Town Center
Type		Residential
Location		Reston, VA
Encumbrances		$ 0
Original Land		20,350
Original Building		91,995
Costs Capitalized Subsequent to Acquisition		813
Land and improvements		20,350
Buildings and Improvements		92,808
Land Held for Development		0
Development and Construction in Progress		0
Total		113,158
Accumulated Depreciation		$ 4,833
Year(s) built / renovated		2,014
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | The Lofts at Atlantic Wharf
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		The Lofts at Atlantic Wharf
Type		Residential
Location		Boston, MA
Encumbrances		$ 0
Original Land		3,529
Original Building		54,891
Costs Capitalized Subsequent to Acquisition		1,579
Land and improvements		3,529
Buildings and Improvements		56,470
Land Held for Development		0
Development and Construction in Progress		0
Total		59,999
Accumulated Depreciation		$ 6,596
Year(s) built / renovated		2,011
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Boston Marriott Cambridge
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Boston Marriott Cambridge
Type		Hotel
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		478
Original Building		37,918
Costs Capitalized Subsequent to Acquisition		32,774
Land and improvements		478
Buildings and Improvements		70,692
Land Held for Development		0
Development and Construction in Progress		0
Total		71,170
Accumulated Depreciation		$ 47,620
Year(s) built / renovated		1,986
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Kendall Center Green Garage (formerly Cambridge Center East Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Green Garage (formerly Cambridge Center East Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		35,035
Costs Capitalized Subsequent to Acquisition		3,840
Land and improvements		0
Buildings and Improvements		38,875
Land Held for Development		0
Development and Construction in Progress		0
Total		38,875
Accumulated Depreciation		$ 8,534
Year(s) built / renovated		1,984
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Kendall Center Yellow Garage (formerly Cambridge Center West Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Yellow Garage (formerly Cambridge Center West Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,256
Original Building		15,697
Costs Capitalized Subsequent to Acquisition		859
Land and improvements		1,256
Buildings and Improvements		16,556
Land Held for Development		0
Development and Construction in Progress		0
Total		17,812
Accumulated Depreciation		$ 4,140
Year(s) built / renovated		2,006
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Kendall Center Blue Garage (formerly Cambridge Center North Garage)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Blue Garage (formerly Cambridge Center North Garage)
Type		Garage
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		1,163
Original Building		11,633
Costs Capitalized Subsequent to Acquisition		1,105
Land and improvements		1,163
Buildings and Improvements		12,738
Land Held for Development		0
Development and Construction in Progress		0
Total		13,901
Accumulated Depreciation		$ 8,630
Year(s) built / renovated		1,990
Depreciable Lives (Years)	[4]	(1)
Boston Properties Limited Partnership [Member] | Salesforce Tower
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Salesforce Tower
Type		Development
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		429,767
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		429,767
Total		429,767
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | 601 Massachusetts Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		601 Massachusetts Avenue
Type		Development
Location		Washington, DC
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		253,166
Land and improvements		95,312
Buildings and Improvements		140,791
Land Held for Development		0
Development and Construction in Progress		17,063
Total		253,166
Accumulated Depreciation		$ 1,531
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | 10 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		10 CityPoint
Type		Development
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		70,226
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		70,226
Total		70,226
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Reston Signature Site
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Signature Site
Type		Development
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		38,886
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		12,678
Development and Construction in Progress		26,208
Total		38,886
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Cambridge Residential / 88 Ames
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Cambridge Residential / 88 Ames
Type		Development
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		9,495
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		0
Development and Construction in Progress		9,495
Total		9,495
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Springfield Metro Center
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Springfield Metro Center
Type		Land
Location		Springfield, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		34,870
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		34,870
Development and Construction in Progress		0
Total		34,870
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Tower Oaks Master Plan
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Tower Oaks Master Plan
Type		Land
Location		Rockville, MD
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		29,022
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		29,022
Development and Construction in Progress		0
Total		29,022
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Plaza at Almaden
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Plaza at Almaden
Type		Land
Location		San Jose, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		29,010
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		29,010
Development and Construction in Progress		0
Total		29,010
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | 6601 & 6605 Springfield Center Drive
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		6601 & 6605 Springfield Center Drive
Type		Land
Location		Springfield, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		13,866
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		13,866
Development and Construction in Progress		0
Total		13,866
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | 214 Third Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		214 Third Avenue
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		13,415
Land and improvements		0
Buildings and Improvements		132
Land Held for Development		13,283
Development and Construction in Progress		0
Total		13,415
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | 103 Fourth Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		103 Fourth Avenue
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		11,927
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		11,927
Development and Construction in Progress		0
Total		11,927
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Reston Gateway
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Gateway
Type		Land
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		10,294
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		10,294
Development and Construction in Progress		0
Total		10,294
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | 20 CityPoint
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		20 CityPoint
Type		Land
Location		Waltham, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		10,258
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		10,258
Development and Construction in Progress		0
Total		10,258
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Reston Eastgate
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Reston Eastgate
Type		Land
Location		Reston, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		9,215
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		9,215
Development and Construction in Progress		0
Total		9,215
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Washingtonian North
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Washingtonian North
Type		Land
Location		Gaithersburg, MD
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		8,836
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		8,836
Development and Construction in Progress		0
Total		8,836
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Crane Meadow
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Crane Meadow
Type		Land
Location		Marlborough, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		8,727
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		8,727
Development and Construction in Progress		0
Total		8,727
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Broad Run Business Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Broad Run Business Park
Type		Land
Location		Loudoun County, VA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		6,399
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		6,399
Development and Construction in Progress		0
Total		6,399
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | North First Master Plan
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		North First Master Plan
Type		Land
Location		San Jose, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		2,999
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		2,999
Development and Construction in Progress		0
Total		2,999
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Fourth and Harrison (formerly 425 Fourth Street)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Fourth and Harrison (formerly 425 Fourth Street)
Type		Land
Location		San Francisco, CA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		2,920
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		2,920
Development and Construction in Progress		0
Total		2,920
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | Kendall Center Master Plan (formerly Cambridge Master Plan)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		Kendall Center Master Plan (formerly Cambridge Master Plan)
Type		Land
Location		Cambridge, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		1,403
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		1,403
Development and Construction in Progress		0
Total		1,403
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Boston Properties Limited Partnership [Member] | 30 Shattuck Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Property Name		30 Shattuck Road
Type		Land
Location		Andover, MA
Encumbrances		$ 0
Original Land		0
Original Building		0
Costs Capitalized Subsequent to Acquisition		1,213
Land and improvements		0
Buildings and Improvements		0
Land Held for Development		1,213
Development and Construction in Progress		0
Total		1,213
Accumulated Depreciation		$ 0
Year(s) built / renovated		N/A
Depreciable Lives (Years)		N/A
Minimum [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life Used for Depreciation		life of the lease
Minimum [Member] | Boston Properties Limited Partnership [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life Used for Depreciation		life of the lease
[1]	Includes the unamortized balance of the historical fair value adjustment totaling approximately $80.2 million.
[2]	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.
[3]	Includes the unamortized balance of the historical fair value adjustment totaling approximately $80.2 million.
[4]	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.

Real Estate and Accumulated 106

Real Estate and Accumulated Depreciation Activity of Real Estate and Accumulated Depreciation (BPLP) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Real Estate, Balance at the beginning of the year	$ 19,208,417	$ 18,953,601	$ 14,869,887
Real Estate, Additions to / improvements of real estate	700,792	594,296	4,410,622
Real Estate, Assets sold / written off	(457,526)	(339,480)	(326,908)
Real Estate, Balance at the end of the year	19,451,683	19,208,417	18,953,601
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Accumulated depreciation, Balance at beginning of the year	3,529,978	3,145,701	2,919,479
Accumulated depreciation, Depreciation expense	486,450	456,176	419,908
Accumulated depreciation, Assets sold / written off	(110,488)	(71,899)	(193,686)
Accumulated depreciation, Balance at end of the year	3,905,940	3,529,978	3,145,701
Boston Properties Limited Partnership [Member]
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Real Estate, Balance at the beginning of the year	18,786,572	18,523,277	14,431,521
Real Estate, Additions to / improvements of real estate	700,792	594,296	4,410,622
Real Estate, Assets sold / written off	(456,075)	(331,001)	(318,866)
Real Estate, Balance at the end of the year	19,031,289	18,786,572	18,523,277
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Accumulated depreciation, Balance at beginning of the year	3,458,640	3,081,040	2,862,302
Accumulated depreciation, Depreciation expense	478,457	447,667	411,860
Accumulated depreciation, Assets sold / written off	(110,235)	(70,067)	(193,122)
Accumulated depreciation, Balance at end of the year	$ 3,826,862	$ 3,458,640	$ 3,081,040