Boston Properties (BXP) 10-Q 7 Nov 16 2016 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Nov. 02, 2016
Entity Information [Line Items]
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
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		153,773,460
Boston Properties Limited Partnership
Entity Information [Line Items]
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
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

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
ASSETS
Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $6,618,753 at September 30, 2016)	$ 19,902,756	$ 19,481,535
Less: accumulated depreciation (amounts related to VIEs of ($713,454) at September 30, 2016)	(4,113,553)	(3,925,894)
Total real estate	15,789,203	15,555,641
Cash and cash equivalents (amounts related to VIEs of $244,026 at September 30, 2016)	419,323	723,718
Cash held in escrows (amounts related to VIEs of $4,988 at September 30, 2016)	63,980	73,790
Investments in securities	23,022	20,380
Tenant and other receivables (amounts related to VIEs of $19,242 at September 30, 2016)	76,258	97,865
Accrued rental income (amounts related to VIEs of $221,031 at September 30, 2016)	785,569	754,883
Deferred charges, net (amounts related to VIEs of $304,358 at September 30, 2016)	680,192	704,867
Prepaid expenses and other assets (amounts related to VIEs of $76,094 at September 30, 2016)	176,693	185,118
Investments in unconsolidated joint ventures	775,659	235,224
Total assets	18,789,899	18,351,486
Liabilities:
Mortgage notes payable, net (amounts related to VIEs of $2,032,714 at September 30, 2016)	2,077,707	3,435,242
Unsecured senior notes, net	7,243,767	5,264,819
Unsecured line of credit	0	0
Mezzanine notes payable (amounts related to VIEs of $307,448 at September 30, 2016)	307,448	308,482
Outside members’ notes payable (amounts related to VIEs of $180,000 at September 30, 2016)	180,000	180,000
Accounts payable and accrued expenses (amounts related to VIEs of $127,846 at September 30, 2016)	312,979	274,709
Dividends and distributions payable	113,038	327,320
Accrued interest payable (amounts related to VIEs of $153,012 at September 30, 2016)	234,628	190,386
Other liabilities (amounts related to VIEs of $195,245 at September 30, 2016)	461,079	483,601
Total liabilities	10,930,646	10,464,559
Commitments and contingencies	0	0
Equity / Capital:
Excess stock, $0.01 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/unit, liquidation preference $2,500 per share/unit, 92,000 shares authorized, 80,000 shares/units issued and outstanding at September 30, 2016 and December 31, 2015	200,000	200,000
Common stock, $0.01 par value, 250,000,000 shares authorized, 153,851,912 and 153,658,866 issued and 153,773,012 and 153,579,966 outstanding at September 30, 2016 and December 31, 2015, respectively	1,538	1,536
Additional paid-in capital	6,326,580	6,305,687
Dividends in excess of earnings	(725,522)	(780,952)
Treasury common stock at cost, 78,900 shares at September 30, 2016 and December 31, 2015	(2,722)	(2,722)
Accumulated other comprehensive loss	(73,943)	(14,114)
Total stockholders’ equity attributable to Boston Properties, Inc.	5,725,931	5,709,435
Noncontrolling interests:
Common units of the Operating Partnership	608,280	603,092
Property partnerships	1,525,042	1,574,400
Total equity / capital	7,859,253	7,886,927
Total liabilities and equity / capital	18,789,899	18,351,486
Boston Properties Limited Partnership
ASSETS
Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $6,618,753 at September 30, 2016)	19,489,365	19,061,141
Less: accumulated depreciation (amounts related to VIEs of ($713,454) at September 30, 2016)	(4,030,172)	(3,846,816)
Total real estate	15,459,193	15,214,325
Cash and cash equivalents (amounts related to VIEs of $244,026 at September 30, 2016)	419,323	723,718
Cash held in escrows (amounts related to VIEs of $4,988 at September 30, 2016)	63,980	73,790
Investments in securities	23,022	20,380
Tenant and other receivables (amounts related to VIEs of $19,242 at September 30, 2016)	76,258	97,865
Accrued rental income (amounts related to VIEs of $221,031 at September 30, 2016)	785,569	754,883
Deferred charges, net (amounts related to VIEs of $304,358 at September 30, 2016)	680,192	704,867
Prepaid expenses and other assets (amounts related to VIEs of $76,094 at September 30, 2016)	176,693	185,118
Investments in unconsolidated joint ventures	775,659	235,224
Total assets	18,459,889	18,010,170
Liabilities:
Mortgage notes payable, net (amounts related to VIEs of $2,032,714 at September 30, 2016)	2,077,707	3,435,242
Unsecured senior notes, net	7,243,767	5,264,819
Unsecured line of credit	0	0
Mezzanine notes payable (amounts related to VIEs of $307,448 at September 30, 2016)	307,448	308,482
Outside members’ notes payable (amounts related to VIEs of $180,000 at September 30, 2016)	180,000	180,000
Accounts payable and accrued expenses (amounts related to VIEs of $127,846 at September 30, 2016)	312,979	274,709
Dividends and distributions payable	113,038	327,320
Accrued interest payable (amounts related to VIEs of $153,012 at September 30, 2016)	234,628	190,386
Other liabilities (amounts related to VIEs of $195,245 at September 30, 2016)	461,079	483,601
Total liabilities	10,930,646	10,464,559
Commitments and contingencies	0	0
Noncontrolling interest:
Redeemable partnership units—17,096,675 and 16,097,473 common units and 905,494 and 1,831,714 long term incentive units outstanding at redemption value at September 30, 2016 and December 31, 2015, respectively	2,453,516	2,286,689
Redeemable interest in property partnership	1,525,042	1,574,400
Preferred stock, $.01 par value, 50,000,000 shares authorized
5.25% Series B cumulative redeemable preferred stock/unit, liquidation preference $2,500 per share/unit, 92,000 shares authorized, 80,000 shares/units issued and outstanding at September 30, 2016 and December 31, 2015	193,623	193,623
Accumulated other comprehensive loss	(85,043)	(18,337)
Noncontrolling interests:
Boston Properties Limited Partnership partners’ capital—1,717,752 and 1,715,092 general partner units and 152,055,260 and 151,864,874 limited partner units outstanding at September 30, 2016 and December 31, 2015, respectively	3,357,062	3,490,899
Total equity / capital	5,075,727	5,258,922
Total liabilities and equity / capital	$ 18,459,889	$ 18,010,170

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
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	153,851,912	153,658,866
Common stock, shares outstanding	153,773,012	153,579,966
Treasury common stock at cost, shares	78,900	78,900
General Partners' Capital Account, Units Outstanding	1,717,752
Limited Partners' Capital Account, Units Outstanding	152,055,260
Real Estate Investment Property, at Cost	$ 19,902,756	$ 19,481,535
Construction in Progress	954,013	763,935
Accumulated depreciation	4,113,553	3,925,894
Cash and Cash Equivalents	419,323	723,718
Restricted Cash and Cash Equivalents	63,980	73,790
Accounts Receivable, Net	76,258	97,865
Deferred Rent Receivables, Net	785,569	754,883
Deferred Charges, net	680,192	704,867
Prepaid expense and other assets	176,693	185,118
Mortgage notes payable, net	2,077,707	3,435,242
Mezzanine notes payable	307,448	308,482
Accounts Payable and Accrued Liabilities	312,979	274,709
Interest Payable	234,628	190,386
Other Liabilities	$ 461,079	$ 483,601
Series B Cumulative Redeemable Preferred Stock [Member]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	92,000	92,000
Series B Dividend Rate Percentage	5.25%	5.25%
Series B, Liquidation Preference Per Share (dollars per share)	$ 2,500	$ 2,500
Series B, shares issued	80,000	80,000
Series B, Shares Outstanding (in shares)	80,000	80,000
Boston Properties Limited Partnership
NonControlling Interest Redeemable Partnership Units Common Units Shares Outstanding	17,096,675	16,097,473
NonControlling Interest Redeemable Partnership Units Common Units Long Term Incentive Units At Redemption Value Shares Outstanding	905,494	1,831,714
General Partners' Capital Account, Units Outstanding	1,717,752	1,715,092
Limited Partners' Capital Account, Units Outstanding	152,055,260	151,864,874
Real Estate Investment Property, at Cost	$ 19,489,365	$ 19,061,141
Construction in Progress	954,013	763,935
Accumulated depreciation	4,030,172	3,846,816
Cash and Cash Equivalents	419,323	723,718
Restricted Cash and Cash Equivalents	63,980	73,790
Accounts Receivable, Net	76,258	97,865
Deferred Rent Receivables, Net	785,569	754,883
Deferred Charges, net	680,192	704,867
Prepaid expense and other assets	176,693	185,118
Mortgage notes payable, net	2,077,707	3,435,242
Mezzanine notes payable	307,448	308,482
Accounts Payable and Accrued Liabilities	312,979	274,709
Interest Payable	234,628	190,386
Other Liabilities	$ 461,079	$ 483,601
Boston Properties Limited Partnership | Series B Cumulative Redeemable Preferred Stock [Member]
Series B Dividend Rate Percentage	5.25%	5.25%
Series B, Liquidation Preference Per Share (dollars per share)	$ 2,500	$ 2,500
Series B, shares issued	80,000	80,000
Series B, Shares Outstanding (in shares)	80,000	80,000
VIE
Real Estate Investment Property, at Cost	$ 6,618,753
Construction in Progress	0
Accumulated depreciation	(713,454)
Cash and Cash Equivalents	244,026
Restricted Cash and Cash Equivalents	4,988
Accounts Receivable, Net	19,242
Deferred Rent Receivables, Net	221,031
Deferred Charges, net	304,358
Prepaid expense and other assets	76,094
Mortgage notes payable, net	2,032,714
Mezzanine notes payable	307,448
Outside member's notes payable	180,000
Accounts Payable and Accrued Liabilities	127,846
Interest Payable	153,012
Other Liabilities	195,245
VIE | Boston Properties Limited Partnership
Real Estate Investment Property, at Cost	6,618,753
Construction in Progress	0
Accumulated depreciation	(713,454)
Cash and Cash Equivalents	244,026
Restricted Cash and Cash Equivalents	4,988
Accounts Receivable, Net	19,242
Deferred Rent Receivables, Net	221,031
Deferred Charges, net	304,358
Prepaid expense and other assets	76,094
Mortgage notes payable, net	2,032,714
Mezzanine notes payable	307,448
Outside member's notes payable	180,000
Accounts Payable and Accrued Liabilities	127,846
Interest Payable	153,012
Other Liabilities	$ 195,245

Consolidated Statements Of Oper

Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue
Base rent	$ 489,312	$ 494,300	$ 1,518,826	$ 1,471,591
Recoveries from tenants	92,560	91,544	267,852	266,932
Parking and other	24,638	25,509	75,576	76,849
Total rental revenue	606,510	611,353	1,862,254	1,815,372
Hotel revenue	12,354	12,619	33,919	35,107
Development and management services	6,364	5,912	18,586	16,102
Total revenue	625,228	629,884	1,914,759	1,866,581
Expenses
Rental	228,560	219,796	665,670	655,610
Hotel	8,118	8,125	23,730	24,196
General and administrative	25,165	20,944	79,936	72,019
Transaction costs	249	254	1,187	789
Impairment loss	1,783	0	1,783	0
Depreciation and amortization	203,748	153,015	516,371	475,082
Total expenses	467,623	402,134	1,288,677	1,227,696
Operating income	157,605	227,750	626,082	638,885
Other income (expense)
Income from unconsolidated joint ventures	1,464	2,647	5,489	20,559
Interest and other income	3,628	3,637	6,657	6,337
Gains (losses) from investments in securities	976	(1,515)	1,713	(1,146)
Interest expense	(104,641)	(108,727)	(314,953)	(326,018)
Losses from early extinguishments of debt	(371)	0	(371)	0
Losses from interest rate contracts	(140)	0	(140)	0
Income before gains on sales of real estate	58,521	123,792	324,477	338,617
Gains on sales of real estate	12,983	199,479	80,606	294,563
Net income	71,504	323,271	405,083	633,180
Net income attributable to noncontrolling interests
Noncontrolling interests in property partnerships	17,225	(115,240)	(53)	(139,712)
Noncontrolling interest—redeemable preferred units	0	0	0	(6)
Noncontrolling interest—common units of the Operating Partnership	(9,387)	(21,302)	(42,120)	(50,906)
Net income attributable to the Company	79,342	186,729	362,910	442,556
Preferred dividends / distributions	(2,589)	(2,647)	(7,796)	(7,854)
Net income attributable to the Company's common shareholders / unitholders	$ 76,753	$ 184,082	$ 355,114	$ 434,702
Basic earnings per common share / unit attributable to the Company's common shareholders / unitholders
Net income (in dollars per share / unit)	$ 0.50	$ 1.20	$ 2.31	$ 2.83
Weighted average number of common shares / units outstanding	153,754	153,595	153,681	153,426
Diluted earnings per common share / unit attributable to the Company's common shareholders / unitholders
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.50	$ 1.20	$ 2.31	$ 2.82
Weighted average number of common and common equivalent shares / units outstanding (in shares / units)	154,136	153,786	153,971	153,825
Dividends / Distributions, Per Share / Unit, Declared	$ 0.65	$ 0.65	$ 1.95	$ 1.95
Boston Properties Limited Partnership
Revenue
Base rent	$ 489,312	$ 494,300	$ 1,518,826	$ 1,471,591
Recoveries from tenants	92,560	91,544	267,852	266,932
Parking and other	24,638	25,509	75,576	76,849
Total rental revenue	606,510	611,353	1,862,254	1,815,372
Hotel revenue	12,354	12,619	33,919	35,107
Development and management services	6,364	5,912	18,586	16,102
Total revenue	625,228	629,884	1,914,759	1,866,581
Expenses
Rental	228,560	219,796	665,670	655,610
Hotel	8,118	8,125	23,730	24,196
General and administrative	25,165	20,944	79,936	72,019
Transaction costs	249	254	1,187	789
Impairment loss	1,783	0	1,783	0
Depreciation and amortization	198,582	151,017	507,234	469,087
Total expenses	462,457	400,136	1,279,540	1,221,701
Operating income	162,771	229,748	635,219	644,880
Other income (expense)
Income from unconsolidated joint ventures	1,464	2,647	5,489	20,559
Interest and other income	3,628	3,637	6,657	6,337
Gains (losses) from investments in securities	976	(1,515)	1,713	(1,146)
Interest expense	(104,641)	(108,727)	(314,953)	(326,018)
Losses from early extinguishments of debt	(371)	0	(371)	0
Losses from interest rate contracts	(140)	0	(140)	0
Income before gains on sales of real estate	63,687	125,790	333,614	344,612
Gains on sales of real estate	12,983	199,723	82,775	294,807
Net income	76,670	325,513	416,389	639,419
Net income attributable to noncontrolling interests
Noncontrolling interests in property partnerships	17,225	(115,240)	(53)	(139,712)
Noncontrolling interest—redeemable preferred units	0	0	0	(6)
Net income attributable to the Company	93,895	210,273	416,336	499,701
Preferred dividends / distributions	(2,589)	(2,647)	(7,796)	(7,854)
Net income attributable to the Company's common shareholders / unitholders	$ 91,306	$ 207,626	$ 408,540	$ 491,847
Basic earnings per common share / unit attributable to the Company's common shareholders / unitholders
Net income (in dollars per share / unit)	$ 0.53	$ 1.21	$ 2.38	$ 2.87
Weighted average number of common shares / units outstanding	171,379	171,160	171,353	171,131
Diluted earnings per common share / unit attributable to the Company's common shareholders / unitholders
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.53	$ 1.21	$ 2.38	$ 2.87
Weighted average number of common and common equivalent shares / units outstanding (in shares / units)	171,761	171,351	171,643	171,530
Dividends / Distributions, Per Share / Unit, Declared	$ 0.65	$ 0.65	$ 1.95	$ 1.95

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income		$ 71,504	$ 323,271	$ 405,083	$ 633,180
Other comprehensive income (loss):
Effective portion of interest rate contracts		5,712	(30,156)	(85,285)	(18,050)
Amortization of interest rate contracts	[1]	1,190	627	2,445	1,882
Other comprehensive income (loss)		6,902	(29,529)	(82,840)	(16,168)
Comprehensive income		78,406	293,742	322,243	617,012
Net income attributable to noncontrolling interests		7,838	(136,542)	(42,173)	(190,624)
Other comprehensive income (loss) attributable to noncontrolling interests		(1,097)	7,056	23,011	4,847
Comprehensive income attributable to the Company		85,147	164,256	303,081	431,235
Boston Properties Limited Partnership
Net income		76,670	325,513	416,389	639,419
Other comprehensive income (loss):
Effective portion of interest rate contracts		5,712	(30,156)	(85,285)	(18,050)
Amortization of interest rate contracts	[2]	1,190	627	2,445	1,882
Other comprehensive income (loss)		6,902	(29,529)	(82,840)	(16,168)
Comprehensive income		83,572	295,984	333,549	623,251
Net income attributable to noncontrolling interests		16,812	(110,784)	16,081	(136,178)
Comprehensive income attributable to the Company		$ 100,384	$ 185,200	$ 349,630	$ 487,073
[1]	Amounts reclassified from comprehensive income primarily to interest expense within the Boston Properties, Inc.’s Consolidated Statements of Operations.
[2]	Amounts reclassified from comprehensive income primarily to interest expense within the 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 (Income) Loss [Member]	Noncontrolling Interests [Member]
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		153,114,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units to Common Stock, shares		419,000
Conversion of operating partnership units to Common Stock, value	0	$ 5		14,152				(14,157)
Allocated net income for the year	628,053				442,556			185,497
Dividends/distributions declared	(342,453)				(307,146)
Dividends/distributions declared								(35,307)
Shares issued pursuant to stock purchase plan, shares		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	33,907	$ 0		4,600				29,307
Acquisition of redeemable noncontrolling interest in property partnership	(1,586)			(1,586)
Contributions from noncontrolling interests in property partnerships	1,758							1,758
Distributions to noncontrolling interests in property partnerships	(144,468)							(144,468)
Effective portion of interest rate contracts	(18,050)						(13,008)	(5,042)
Amortization of interest rate contracts	1,882						1,687	195
Reallocation of noncontrolling interest	0			12,577				(12,577)
Equity, value at Sep. 30, 2015	8,062,759	$ 1,536	200,000	6,300,780	(627,054)	(2,722)	(20,625)	2,210,844
Equity, shares at Sep. 30, 2015		153,575,000
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units to Common Stock, shares		173,000
Conversion of operating partnership units to Common Stock, value		$ 2		5,879				(5,881)
Allocated net income for the year	$ 405,083				362,910			42,173
Dividends/distributions declared	(342,980)				(307,480)
Dividends/distributions declared								(35,500)
Shares issued pursuant to stock purchase plan, shares		6,000
Shares issued pursuant to stock purchase plan, value	730			730
Net activity from stock option and incentive plan, shares		14,000
Net activity from stock option and incentive plan, value	24,290			2,870				21,420
Sale of interests in property partnerships				1,320				(1,320)
Contributions from noncontrolling interests in property partnerships	6,737							6,737
Distributions to noncontrolling interests in property partnerships	(38,694)							(38,694)
Effective portion of interest rate contracts	(85,285)						(62,022)	(23,263)
Amortization of interest rate contracts	2,445						2,193	252
Reallocation of noncontrolling interest				10,094				(10,094)
Equity, value at Sep. 30, 2016	$ 7,859,253	$ 1,538	$ 200,000	$ 6,326,580	$ (725,522)	$ (2,722)	$ (73,943)	$ 2,133,322
Equity, shares at Sep. 30, 2016	153,773,012	153,773,000

Consolidated Statement of Partn

Consolidated Statement of Partners' Capital Statement - USD ($) $ in Thousands	Total	Boston Properties Limited Partnership
Beginning Balance at Dec. 31, 2014		$ 3,639,916
Contributions		5,126
Acquisition of redeemable noncontrolling interest in property partnership	$ (1,586)	(1,586)
Net income allocable to general and limited partner units		448,795
Distributions		(307,146)
Accumulated other comprehensive loss		(11,321)
Unearned compensation		254
Conversion of redeemable partnership units		14,157
Adjustment to reflect redeemable partnership units at redemption value		216,037
Ending Balance at Sep. 30, 2015		4,004,232
Beginning Balance at Dec. 31, 2015		3,684,522
Contributions		3,269
Net income allocable to general and limited partner units		374,216
Distributions		(307,480)
Accumulated other comprehensive loss		(59,829)
Unearned compensation		1,651
Conversion of redeemable partnership units		5,881
Adjustment to reflect redeemable partnership units at redemption value		(151,545)
Ending Balance at Sep. 30, 2016		$ 3,550,685

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net income	$ 405,083	$ 633,180
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	516,371	475,082
Impairment loss	1,783	0
Non-cash compensation expense	25,290	22,825
Income from unconsolidated joint ventures	(5,489)	(20,559)
Distributions of net cash flow from operations of unconsolidated joint ventures	11,645	6,484
Losses (gains) from investments in securities	(1,713)	1,146
Losses from early extinguishments of debt	371	0
Non-cash portion of interest expense	(27,386)	(32,818)
Gains on sales of real estate	(80,606)	(294,563)
Change in assets and liabilities:
Cash held in escrows	1,675	(32,750)
Tenant and other receivables, net	22,135	(19,851)
Accrued rental income, net	(14,618)	(55,941)
Prepaid expenses and other assets	4,883	20,988
Accounts payable and accrued expenses	16,852	(2,937)
Accrued interest payable	44,242	37,384
Other liabilities	(114,321)	(73,370)
Tenant leasing costs	(62,412)	(55,422)
Total adjustments	338,702	(24,302)
Net cash provided by operating activities	743,785	608,878
Cash flows from investing activities:
Acquisition of real estate	(78,000)	0
Construction in progress	(359,716)	(251,984)
Building and other capital improvements	(81,842)	(84,644)
Tenant improvements	(167,762)	(86,052)
Proceeds from sales of real estate	122,750	389,457
Proceeds from sales of real estate placed in escrow	(122,647)	(200,612)
Proceeds from sales of real estate released from escrow	122,647	634,165
Cash placed in escrow for land sale contracts	0	(7,111)
Cash released from escrow for land sale contracts	1,403	3,250
Cash released from escrow for investing activities	6,694	0
Capital contributions to unconsolidated joint ventures	(546,982)	(20,863)
Capital distributions from unconsolidated joint ventures	0	24,527
Investments in securities, net	(929)	(1,332)
Net cash provided by (used in) investing activities	(1,104,384)	398,801
Cash flows from financing activities:
Repayments of mortgage notes payable	(1,323,284)	(20,137)
Proceeds from unsecured senior notes	1,989,790	0
Proceeds from real estate financing transaction	0	6,000
Payments on real estate financing transactions	(4,712)	(2,364)
Deferred financing costs	(16,101)	(1,288)
Net proceeds from equity transactions	(270)	799
Redemption of preferred units	0	(633)
Dividends and distributions	(557,262)	(1,112,019)
Acquisition of noncontrolling interest	0	(108,499)
Contributions from noncontrolling interests in property partnerships	6,737	1,758
Distributions to noncontrolling interests in property partnerships	(38,694)	(147,368)
Net cash provided by (used in) financing activities	56,204	(1,383,751)
Net decrease in cash and cash equivalents	(304,395)	(376,072)
Cash and cash equivalents, beginning of period	723,718	1,763,079
Cash and cash equivalents, end of period	419,323	1,387,007
Supplemental disclosures:
Cash paid for interest	327,053	347,367
Interest capitalized	28,956	25,915
Non-cash investing and financing activities:
Write off of fully depreciated real estate	(168,861)	(33,532)
Additions to real estate included in accounts payable and accrued expenses	11,864	28,246
Dividends and distributions declared but not paid	113,038	112,912
Mortgage notes payable assigned in connection with the sale of real estate	0	116,993
Conversions of noncontrolling interests to stockholders’ equity	5,881	14,157
Issuance of restricted securities to employees	33,711	43,363
Boston Properties Limited Partnership
Cash flows from operating activities:
Net income	416,389	639,419
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	507,234	469,087
Impairment loss	1,783	0
Non-cash compensation expense	25,290	22,825
Income from unconsolidated joint ventures	(5,489)	(20,559)
Distributions of net cash flow from operations of unconsolidated joint ventures	11,645	6,484
Losses (gains) from investments in securities	(1,713)	1,146
Losses from early extinguishments of debt	371	0
Non-cash portion of interest expense	(27,386)	(32,818)
Gains on sales of real estate	(82,775)	(294,807)
Change in assets and liabilities:
Cash held in escrows	1,675	(32,750)
Tenant and other receivables, net	22,135	(19,851)
Accrued rental income, net	(14,618)	(55,941)
Prepaid expenses and other assets	4,883	20,988
Accounts payable and accrued expenses	16,852	(2,937)
Accrued interest payable	44,242	37,384
Other liabilities	(114,321)	(73,370)
Tenant leasing costs	(62,412)	(55,422)
Total adjustments	327,396	(30,541)
Net cash provided by operating activities	743,785	608,878
Cash flows from investing activities:
Acquisition of real estate	(78,000)	0
Construction in progress	(359,716)	(251,984)
Building and other capital improvements	(81,842)	(84,644)
Tenant improvements	(167,762)	(86,052)
Proceeds from sales of real estate	122,750	389,457
Proceeds from sales of real estate placed in escrow	(122,647)	(200,612)
Proceeds from sales of real estate released from escrow	122,647	634,165
Cash placed in escrow for land sale contracts	0	(7,111)
Cash released from escrow for land sale contracts	1,403	3,250
Cash released from escrow for investing activities	6,694	0
Capital contributions to unconsolidated joint ventures	(546,982)	(20,863)
Capital distributions from unconsolidated joint ventures	0	24,527
Investments in securities, net	(929)	(1,332)
Net cash provided by (used in) investing activities	(1,104,384)	398,801
Cash flows from financing activities:
Repayments of mortgage notes payable	(1,323,284)	(20,137)
Proceeds from unsecured senior notes	1,989,790	0
Proceeds from real estate financing transaction	0	6,000
Payments on real estate financing transactions	(4,712)	(2,364)
Deferred financing costs	(16,101)	(1,288)
Net proceeds from equity transactions	(270)	799
Redemption of preferred units	0	(633)
Dividends and distributions	(557,262)	(1,112,019)
Acquisition of noncontrolling interest	0	(108,499)
Contributions from noncontrolling interests in property partnerships	6,737	1,758
Distributions to noncontrolling interests in property partnerships	(38,694)	(147,368)
Net cash provided by (used in) financing activities	56,204	(1,383,751)
Net decrease in cash and cash equivalents	(304,395)	(376,072)
Cash and cash equivalents, beginning of period	723,718	1,763,079
Cash and cash equivalents, end of period	419,323	1,387,007
Supplemental disclosures:
Cash paid for interest	327,053	347,367
Interest capitalized	28,956	25,915
Non-cash investing and financing activities:
Write off of fully depreciated real estate	(168,861)	(33,532)
Additions to real estate included in accounts payable and accrued expenses	11,864	28,246
Dividends and distributions declared but not paid	113,038	112,912
Mortgage notes payable assigned in connection with the sale of real estate	0	116,993
Conversions of noncontrolling interests to stockholders’ equity	5,881	14,157
Issuance of restricted securities to employees	$ 33,711	$ 43,363

Organization

Organization	9 Months Ended
	Sep. 30, 2016
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, its operating partnership, and at September 30, 2016 owned an approximate 89.5% ( 89.5% at December 31, 2015 ) 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, and its consolidated subsidiaries. Partnership interests in Boston Properties Limited Partnership include: • common units of partnership interest (also referred to as “OP Units”), • long term incentive units of partnership interest (also referred to as “LTIP Units”), and • preferred units of partnership interest (also referred to as “Preferred Units”). 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. The Company uses LTIP Units as a form of equity-based award for annual long-term incentive equity compensation. The Company has also issued LTIP Units to employees in the form of (1) 2012 outperformance plan awards (“2012 OPP Units”) and (2) 2013, 2014, 2015 and 2016 multi-year, long-term incentive program awards (also referred to as “2013 MYLTIP Units,” “2014 MYLTIP Units,” “2015 MYLTIP Units” and “2016 MYLTIP Units,” respectively, and collectively as “MYLTIP Units”), each of which, upon the satisfaction of certain performance and vesting conditions, is convertible into one OP Unit. The three-year measurement periods for the 2012 OPP Units and 2013 MYLTIP Units expired on February 6, 2015 and February 4, 2016, respectively, 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 awards. Unless and until they are earned, the rights, preferences and privileges of the 2014, 2015 and 2016 MYLTIP Units differ from other LTIP Units granted to employees (including, as of February 6, 2015, the 2012 OPP Units and, as of February 4, 2016, the 2013 MYLTIP Units). Therefore, unless specifically noted otherwise, all references to LTIP Units exclude the 2014, 2015 and 2016 MYLTIP Units. LTIP Units (including the 2012 OPP Units and the 2013 MYLTIP 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 Notes 9 , 10 and 12 ). At September 30, 2016 , 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. on March 27, 2013 in connection with 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 10 ). Properties At September 30, 2016 , the Company owned or had interests in a portfolio of 174 commercial real estate properties (the “Properties”) aggregating approximately 47.7 million net rentable square feet of primarily Class A office properties, including eight properties under construction/redevelopment totaling approximately 4.0 million net rentable square feet. At September 30, 2016 , the Properties consisted of: • 164 Office properties (including six properties under construction/redevelopment); • one hotel; • five retail properties; and • four residential properties (including two properties under construction). 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.

Basis Of Presentation And Summa

Basis Of Presentation And Summary Of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Basis Of Presentation And Summary Of Significant Accounting Policies	2. Basis of Presentation and Summary of Significant Accounting Policies Boston Properties, Inc. does not have any other significant assets, liabilities or operations, other than its investment in 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. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income. The accompanying interim financial statements are unaudited; however, the financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting solely of normal recurring matters) necessary for a fair statement of the financial statements for these interim periods have been included. The results of operations for the interim periods are not necessarily indicative of the results to be obtained for other interim periods or for the full fiscal year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosure required by GAAP. These financial statements should be read in conjunction with the Company’s financial statements and notes thereto contained in the Company’s Annual Report in the Company’s Form 10-K for its fiscal year ended December 31, 2015 . Beginning on January 1, 2016, the properties that were historically included in the Company’s Office/Technical segment are now included in the Office segment (See Note 13 ). Fair Value of Financial Instruments The Company determines the fair value of its unsecured senior notes using market prices. The inputs used in determining the fair value of the Company’s unsecured senior notes are categorized at a level 1 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company uses quoted market rates to value these instruments. However, the inputs used in determining the fair value could be categorized at a level 2 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) if trading volumes are low. The Company determines the fair value of its mortgage notes payable using discounted cash flow analysis 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, and the Company’s estimated fair values for these instruments as of the end of the applicable reporting period are not necessarily indicative of estimated or actual fair values in future reporting periods. The following table presents the aggregate carrying value of the Company’s mortgage notes payable, net, mezzanine notes payable and unsecured senior notes, net and the Company’s corresponding estimate of fair value as of September 30, 2016 and December 31, 2015 (in thousands): September 30, 2016 December 31, 2015 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Mortgage notes payable, net $ 2,077,707 $ 2,111,614 $ 3,435,242 $ 3,503,746 Mezzanine notes payable 307,448 309,095 308,482 306,103 Unsecured senior notes, net 7,243,767 7,761,908 5,264,819 5,547,738 Total $ 9,628,922 $ 10,182,617 $ 9,008,543 $ 9,357,587 The Company uses interest rate swap agreements to manage its interest rate risk. The valuation of these instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. To comply with the provisions of ASC 820, the Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by the Company and its counterparties. However, as of September 30, 2016 , the Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. Variable Interest Entities (VIEs) On January 1, 2016, the Company adopted Accounting Standards Update (“ASU”) 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 (1) modifies the evaluation of whether limited partnerships and similar legal entities are VIEs or voting interest entities, (2) eliminates the presumption that a general partner should consolidate a limited partnership and (3) affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships. The Company reviewed all of its legal entities in accordance with ASU 2015-02 and concluded that certain of its legal entities, including Boston Properties Limited Partnership, which had been consolidated in accordance with the voting interest model, are now variable interest entities under the VIE model, as discussed below. The adoption of the guidance did not alter any of the Company’s consolidation conclusions, but resulted in additional disclosures. Consolidated VIEs are those where the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which 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 VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE. The Company has determined that it is the primary beneficiary for seven of the eight entities that are VIEs. Consolidated Variable Interest Entities As of September 30, 2016 , Boston Properties, Inc. has identified seven consolidated VIEs, including Boston Properties Limited Partnership. The VIEs own (1) the following five in-service properties: 767 Fifth Avenue (the General Motors Building), Time Square Tower, 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street and (2) the entity that owns Salesforce Tower, which is currently under development. The Company consolidates these VIEs as it is the primary beneficiary. The third parties’ interests in these consolidated entities, with the exception of Boston Properties Limited Partnership, are reflected as noncontrolling interest in property partnerships in the accompanying Consolidated Financial Statements (See Note 9 ). In addition, Boston Properties, Inc.’s significant asset is its investment in Boston Properties Limited Partnership and, consequently, substantially all of Boston Properties, Inc.’s assets and liabilities are the assets and liabilities of Boston Properties Limited Partnership. All of Boston Properties, Inc.’s debt is an obligation of Boston Properties Limited Partnership. Variable Interest Entities Not Consolidated The Company has determined that its BNY Tower Holdings LLC joint venture, which owns Dock72 at the Brooklyn Navy Yard, is a VIE. The Company does not consolidate this entity as the Company does not have the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and, therefore, the Company is not considered to be the primary beneficiary. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU 2014-09, “Revenue from Contract with Customers (Topic 606)” (“ASU 2014-09”). The objective of ASU 2014-09 is to establish a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and will supersede most of the existing revenue recognition guidance, including industry-specific guidance. The core principle is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In applying ASU 2014-09, companies will perform a five-step analysis of transactions to determine when and how revenue is recognized. ASU 2014-09 applies to all contracts with customers except those that are within the scope of other topics in the FASB’s Accounting Standards Codification (“ASC”). In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date (“ASU 2015-14”), which delayed the effective date of ASU 2014-09 by one year making it effective for the first interim period within annual reporting periods beginning after December 15, 2017. Early adoption is permitted as of the original effective date. The Company is currently assessing the potential impact that the adoption of ASU 2014-09 will have on its 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 is permitted for financial statements that have not been previously issued. On January 1, 2016, the Company adopted ASU 2015-03 and retrospectively applied the guidance to its Mortgage Notes Payable and Unsecured Senior Notes for all periods presented. Unamortized deferred financing costs, which were previously included in Deferred Charges, Net, totaling approximately $2.5 million and $36.8 million are included in Mortgage Notes Payable, Net and Unsecured Senior Notes, Net, respectively, as of September 30, 2016 and approximately $3.5 million and $24.5 million are included in Mortgage Notes Payable, Net and Unsecured Senior Notes, Net, respectively, as of December 31, 2015. 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 the Company for reporting periods beginning after December 15, 2017. 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. In March 2016, the FASB issued ASU 2016-05, “Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships” (“ASU 2016-05”), which provides guidance clarifying that a novation of party to a derivative instrument, whereby one of the parties to a derivative instrument is replaced with another party, does not, in and of itself, require de-designation of that hedging relationship provided that all other hedge criteria continue to be met. ASU 2016-05 is effective for the Company for reporting periods beginning after December 15, 2016, with early adoption permitted. The Company is currently assessing the potential impact that the adoption of ASU 2016-05 will have on its consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting” (“ASU 2016-09”) . ASU 2016-09 is intended to improve the accounting for share-based payments and affects all organizations that issue share-based payment awards to their employees. Several aspects of the accounting for share-based payment awards are simplified with ASU 2016-09, including income tax consequences, classification of awards as equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for the Company for reporting periods beginning after December 15, 2016, with early adoption permitted. The Company is currently assessing the potential impact that the adoption of ASU 2016-09 will have on its consolidated financial statements. In May 2016, the FASB issued ASU No. 2016-12, “Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients” (“ASU 2016-12”). ASU 2016-12 is intended to clarify and provide practical expedients for certain aspects of ASU 2014-09, which outlines a single comprehensive model for entities to use in accounting for revenues arising from contracts with customers and notes that lease contracts with customers are a scope exception. The Company may elect to adopt ASU 2016-12 as of the original effective date; however, adoption is required for annual reporting periods beginning after December 15, 2017. The Company is currently assessing the potential impact that the adoption of ASU 2016-12 will have on its consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force)” (“ASU 2016-15”). ASU 2016-15 is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The areas addressed in the new guidance related to debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned and bank-owned life insurance policies, distributions received from equity method investments, beneficial interest in securitization transactions, and separately identifiable cash flows and application of the predominance principle. ASU 2016-15 is effective for the Company for reporting periods beginning after December 15, 2017, with early adoption permitted, provided that all of the amendments are adopted in the same period. The Company is currently assessing the potential impact that the adoption of ASU 2016-15 will have on its consolidated financial statements.

Real Estate

Real Estate	9 Months Ended
	Sep. 30, 2016
Real Estate [Abstract]
Real Estate	Boston Properties, Inc. Real estate consisted of the following at September 30, 2016 and December 31, 2015 (in thousands): September 30, 2016 December 31, 2015 Land $ 4,879,020 $ 4,806,021 Land held for future development (1) 243,887 252,195 Buildings and improvements 11,792,853 11,709,285 Tenant improvements 2,001,259 1,920,247 Furniture, fixtures and equipment 31,724 29,852 Construction in progress 954,013 763,935 Total 19,902,756 19,481,535 Less: Accumulated depreciation (4,113,553 ) (3,925,894 ) $ 15,789,203 $ 15,555,641 _______________ (1) Includes pre-development costs. Boston Properties Limited Partnership Real estate consisted of the following at September 30, 2016 and December 31, 2015 (in thousands): September 30, 2016 December 31, 2015 Land $ 4,774,460 $ 4,700,793 Land held for future development (1) 243,887 252,195 Buildings and improvements 11,484,022 11,394,119 Tenant improvements 2,001,259 1,920,247 Furniture, fixtures and equipment 31,724 29,852 Construction in progress 954,013 763,935 Total 19,489,365 19,061,141 Less: Accumulated depreciation (4,030,172 ) (3,846,816 ) $ 15,459,193 $ 15,214,325 _______________ (1) Includes pre-development costs. Acquisitions On April 22, 2016, the Company acquired 3625-3635 Peterson Way located in Santa Clara, California for a purchase price of approximately $78.0 million in cash. 3625-3635 Peterson Way is an approximately 218,000 net rentable square foot office property. The property is 100% leased to a single tenant through March 2021. Following the lease expiration, the Company intends to develop the site into a Class A office campus containing an aggregate of approximately 632,000 net rentable square feet. The following table summarizes the allocation of the aggregate purchase price of 3625-3635 Peterson Way at the date of acquisition (in thousands). Land $ 63,206 Building and improvements 7,210 Tenant improvements 7,669 In-place lease intangibles 4,262 Below-market lease intangible (4,347 ) Net assets acquired $ 78,000 The following table summarizes the estimated annual amortization of the acquired below-market lease intangible and the acquired in-place lease intangibles for 3625-3635 Peterson Way for the remainder of 2016 and each of the next four succeeding fiscal years (in thousands). Acquired In-Place Lease Intangibles Acquired Below- Market Lease Intangible Period from April 22, 2016 through December 31, 2016 $ 578 $ (589 ) 2017 867 (884 ) 2018 867 (884 ) 2019 867 (884 ) 2020 867 (884 ) 3625-3635 Peterson Way contributed approximately $2.4 million of revenue and approximately $6,000 of earnings to the Company for the period from April 22, 2016 through September 30, 2016. Dispositions 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 . Net cash proceeds totaled approximately $104.9 million , resulting in a gain on sale of real estate totaling approximately $60.8 million for Boston Properties, Inc. and approximately $63.0 million for Boston Properties Limited Partnership. 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 11th lease year, which option was exercised by the tenant on October 22, 2014. 415 Main Street is an office property with approximately 231,000 net rentable square feet. 415 Main Street contributed approximately $1.2 million of net income to the Company for the period from January 1, 2016 through January 31, 2016 and contributed approximately $(35,000) and $6.2 million of net income (loss) to the Company for the three and nine months ended September 30, 2015 , respectively. On August 16, 2016, the Company completed the sale of a parcel of land within its Broad Run Business Park property located in Loudoun County, Virginia for a gross sale price of approximately $18.0 million . Net cash proceeds totaled approximately $17.9 million , resulting in a gain on sale of real estate totaling approximately $13.0 million . On September 27, 2016, the Company executed a letter of intent for the sale of the remaining parcel of land at its Washingtonian North property located in Gaithersburg, Maryland. The letter of intent caused the Company to reevaluate its strategy for the land and, based on a shorter than expected hold period, the Company reduced the carrying value of the land to the estimated net sales price and recognized an impairment loss of approximately $1.8 million during the three and nine months ended September 30, 2016. Development On May 27, 2016, the Company completed and fully placed in-service 601 Massachusetts Avenue, a Class A office project with approximately 479,000 net rentable square feet located in Washington, DC. On May 27, 2016, the Company completed and fully placed in-service 804 Carnegie Center, a Class A office project with approximately 130,000 net rentable square feet located in Princeton, New Jersey. On June 24, 2016, the Company completed and fully placed in-service 10 CityPoint, a Class A office project with approximately 241,000 net rentable square feet located in Waltham, Massachusetts. On August 19, 2016, the consolidated entity in which the Company has a 55% interest and that owns 601 Lexington Avenue located in New York City commenced the redevelopment of the six-story low-rise office and retail building component of the complex. The redeveloped portion of the low-rise building will contain approximately 195,000 net rentable square feet of Class A office space and approximately 25,000 net rentable square feet of retail space. The Company will capitalize incremental costs during the redevelopment. Boston Properties, Inc. and Boston Properties Limited Partnership recognized approximately $50.8 million and $47.6 million , respectively, of depreciation expense associated with the acceleration of depreciation on the assets being removed from service and demolished as part of the redevelopment of the property. Approximately $21.4 million of those amounts was allocated to the outside partners and is included within Noncontrolling Interests in Property Partnerships in the Company’s Consolidated Statements of Operations. On September 16, 2016, the Company partially placed in-service 888 Boylston Street, a Class A office project with approximately 425,000 net rentable square feet located in Boston, Massachusetts. Lease Terminations 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 was recognized as termination income and is included in Base Rent in the Consolidated Statements of Operations for the nine months ended September 30, 2016 .

Investments in Unconsolidated J

Investments in Unconsolidated Joint Ventures	9 Months Ended
	Sep. 30, 2016
Investments In Unconsolidated Joint Ventures [Abstract]
Investments In Unconsolidated Joint Ventures	4. Investments in Unconsolidated Joint Ventures The investments in unconsolidated joint ventures consist of the following at September 30, 2016 and December 31, 2015 : Nominal % Ownership Carrying Value of Investment (1) Entity Properties September 30, 2016 December 31, 2015 (in thousands) Square 407 Limited Partnership Market Square North 50.0 % $ (8,483 ) $ (9,951 ) The Metropolitan Square Associates LLC Metropolitan Square 51.0 % 9,552 9,179 BP/CRF 901 New York Avenue LLC 901 New York Avenue 25.0 % (2) (10,898 ) (11,958 ) WP Project Developer LLC Wisconsin Place Land and Infrastructure 33.3 % (3) 42,073 43,524 Annapolis Junction NFM, LLC Annapolis Junction 50.0 % (4) 21,075 29,009 540 Madison Venture LLC 540 Madison Avenue 60.0 % 69,602 68,983 500 North Capitol Venture LLC 500 North Capitol Street, NW 30.0 % (3,395 ) (3,292 ) 501 K Street LLC 1001 6th Street 50.0 % (5) 42,541 42,584 Podium Developer LLC The Hub on Causeway 50.0 % 33,820 18,508 1265 Main Office JV LLC 1265 Main Street 50.0 % 23,757 11,916 BNY Tower Holdings LLC (6) Dock72 at the Brooklyn Navy Yard 50.0 % 25,980 11,521 CA-Colorado Center Limited Partnership Colorado Center 49.8 % 507,259 N/A $ 752,883 $ 210,023 _______________ (1) Investments with deficit balances aggregating approximately $22.8 million and $25.2 million at September 30, 2016 and December 31, 2015 , respectively, have been reflected within Other Liabilities in 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 for this land parcel, the partner will be entitled to up to two additional payments from the venture based on increases in total entitled square footage of the project above 520,000 square feet and achieving certain project returns at stabilization. (6) The entity is a VIE (See Note 2 ). 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. With limited exception, under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners. 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. The combined summarized balance sheets of the Company’s unconsolidated joint ventures are as follows: September 30, 2016 December 31, 2015 (in thousands) ASSETS Real estate and development in process, net $ 1,460,808 $ 1,072,412 Other assets 294,912 252,285 Total assets $ 1,755,720 $ 1,324,697 LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY Mortgage and notes payable, net $ 826,807 $ 830,125 Other liabilities 54,390 44,549 Members’/Partners’ equity 874,523 450,023 Total liabilities and members’/partners’ equity $ 1,755,720 $ 1,324,697 Company’s share of equity $ 449,351 $ 237,070 Basis differentials (1) 303,532 (27,047 ) Carrying value of the Company’s investments in unconsolidated joint ventures (2) $ 752,883 $ 210,023 _______________ (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 result from impairments of investments, acquisitions through joint ventures with no change in control 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. At September 30, 2016, there is an aggregate basis differential of approximately $330.1 million between the carrying value of the Company’s investment in the joint venture that owns Colorado Center and the joint venture’s basis in the assets and liabilities, which differential (excluding land) shall be amortized over the remaining lives of the related assets and liabilities. (2) Investments with deficit balances aggregating approximately $22.8 million and $25.2 million at September 30, 2016 and December 31, 2015 , respectively, have been reflected within Other Liabilities in the Company’s Consolidated Balance Sheets. The combined summarized statements of operations of the Company’s unconsolidated joint ventures are as follows: Three months ended September 30, Nine months ended September 30, 2016 2015 2016 2015 (in thousands) Total revenue (1) $ 49,002 $ 38,197 $ 125,039 $ 116,881 Expenses Operating 21,753 15,896 54,779 47,995 Depreciation and amortization 12,038 8,832 30,306 26,854 Total expenses 33,791 24,728 85,085 74,849 Operating income 15,211 13,469 39,954 42,032 Other expense Interest expense 8,400 8,019 25,172 23,985 Net income $ 6,811 $ 5,450 $ 14,782 $ 18,047 Company’s share of net income $ 3,179 $ 2,481 $ 6,830 $ 20,025 (2) Basis differential (3) (1,715 ) 166 (1,341 ) 534 Income from unconsolidated joint ventures $ 1,464 $ 2,647 $ 5,489 $ 20,559 _______________ (1) Includes straight-line rent adjustments of approximately $5.2 million and $(0.3) million for the three months ended September 30, 2016 and 2015 , respectively, and approximately $11.0 million and $1.7 million for the nine months ended September 30, 2016 and 2015 , respectively. (2) During the nine months ended September 30, 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 nine months ended September 30, 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. (3) Includes a straight-line rent adjustment of approximately $0.7 million and a net above-/below-market rent adjustment of approximately $0.5 million for the three and nine months ended September 30, 2016 . On April 4, 2016, a joint venture in which the Company has a 50% interest extended the loan collateralized by its Annapolis Junction Building Seven property. At the time of the extension, the outstanding balance of the loan totaled approximately $21.5 million and was scheduled to mature on April 4, 2016. The extended loan has a total commitment amount of $22.0 million , bears interest at a variable rate equal to LIBOR plus 1.65% per annum and matures on April 4, 2017, with one , one -year extension option, subject to certain conditions. Annapolis Junction Building Seven is a Class A office property with approximately 127,000 net rentable square feet located in Annapolis, Maryland. On April 11, 2016, a joint venture in which the Company has a 50% interest received a notice of event of default from the lender for the loan collateralized by its Annapolis Junction Building One property. The event of default relates to the loan to value ratio not being in compliance with the loan agreement. The joint venture is currently in discussions with the lender regarding the event of default, although there can be no assurance as to the outcome of those discussions. The estimated fair value of the Company’s investment in the unconsolidated joint venture exceeds its carrying value. The loan has an outstanding balance of approxim ately $39.7 million , is non -recourse to the Company, bears interest at a variable rate equal to LIBOR plus 1.75% per annum and has a stated maturity date of March 31, 2018, with one , three -year extension option, subject to certain conditions. Annapolis Junction Building One is a Class A office property with approximately 118,000 net rentable square feet located in Annapolis, Maryland. On July 1, 2016, the Company entered the Los Angeles market through its acquisition of a 49.8% interest in an existing joint venture that owns and operates Colorado Center located in Santa Monica, California for a gross purchase price of approximately $511.1 million , or approximately $503.6 million in cash net of credits for free rent, unfunded leasing costs and other adjustments. Colorado Center is a six -building office complex that sits on a 15 -acre site and contains an aggregate of approximately 1,184,000 net rentable square feet with an underground parking garage for 3,100 vehicles. The following table summarizes the allocation of the Company's aggregate purchase price for its 49.8% interest in Colorado Center at the date of acquisition (in thousands). Land and improvements $ 189,597 Site improvements 9,050 Building and improvements 259,592 Tenant improvements 17,234 In-place lease intangibles 43,157 Above-market lease intangible 819 Below-market lease intangible (16,461 ) Net assets $ 502,988

Mortgage Notes Payable (Notes)

Mortgage Notes Payable (Notes)	9 Months Ended
	Sep. 30, 2016
Mortgage Notes Payable [Abstract]
Mortgage Notes Payable Disclosure [Text Block]	5. Mortgage Notes Payable On April 11, 2016, the Company used available cash to repay the mortgage loan collateralized by its Fountain Square property located in Reston, Virginia totaling approximately $211.3 million . The mortgage loan bore interest at a fixed rate of 5.71% per annum and was scheduled to mature on October 11, 2016. There was no prepayment penalty. On September 1, 2016, the Company used a portion of the net proceeds from Boston Properties Limited Partnership’s offering of senior unsecured notes (See Note 6 ) and available cash to repay the mortgage loan collateralized by its 599 Lexington Avenue property located in New York City totaling $750.0 million . The mortgage loan bore interest at a fixed rate of 5.57% per annum ( 5.41% per annum including the impact of financing costs and interest rate hedges) and was scheduled to mature on March 1, 2017. There was no prepayment penalty. The Company recognized a gain from early extinguishment of debt totaling approximately $0.4 million consisting of the acceleration of the remaining balance related to the effective portion of a previous interest rate hedging program included within accumulated other comprehensive loss, offset by the write-off of unamortized deferred financing costs. On September 1, 2016, the Company used a portion of the net proceeds from Boston Properties Limited Partnership’s offering of senior unsecured notes (See Note 6 ) and available cash to repay the mortgage loan collateralized by its Embarcadero Center Four property located in San Francisco, California totaling approximately $344.8 million . The mortgage loan bore interest at a fixed rate of 6.10% per annum ( 7.02% per annum including the impact of financing costs and interest rate hedges)and was scheduled to mature on December 1, 2016. There was no prepayment penalty. The Company recognized a loss from early extinguishment of debt totaling approximately $0.7 million consisting of the write-off of unamortized deferred financing costs and the acceleration of the remaining balance related to the effective portion of a previous interest rate hedging program included within accumulated other comprehensive loss.

Unsecured Senior Notes Unsecure

Unsecured Senior Notes Unsecured Senior Notes	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Unsecured Senior Notes	6. Unsecured Senior Notes The following summarizes the unsecured senior notes outstanding as of September 30, 2016 (dollars in thousands): 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 10 Year Unsecured Senior Notes 3.650 % 3.766 % 1,000,000 February 1, 2026 10 Year Unsecured Senior Notes 2.750 % 3.495 % 1,000,000 October 1, 2026 Total principal 7,300,000 Net unamortized discount (19,429 ) Deferred financing costs, net (36,804 ) Total $ 7,243,767 _______________ (1) Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts 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 September 30, 2016 , Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements. 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 approximately 3.766% per annum 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 transaction expenses. On August 17, 2016, Boston Properties Limited Partnership completed a public offering of $1.0 billion in aggregate principal amount of its 2.750% senior unsecured notes due 2026. The notes were priced at 99.271% of the principal amount to yield an effective rate, including financing fees and the impact of the settlement of certain forward-starting interest rate swap contracts (See Note 7 ), of approximately 3.495% per annum to maturity. The notes will mature on October 1, 2026, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $984.7 million after deducting underwriting discounts and transaction expenses.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities (Notes)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities [Text Block]	7. Derivative Instruments and Hedging Activities Boston Properties Limited Partnership had entered into seventeen forward-starting interest rate swap contracts that fixed 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. On August 17, 2016, in conjunction with Boston Properties Limited Partnership’s offering of its 2.750% unsecured senior notes due 2026 (See Note 6 ), the Company terminated the forward-starting interest rate swap contracts and cash-settled the contracts by making cash payments to the counterparties aggregating approximately $49.3 million . The Company recognized approximately $0.1 million of losses on interest rate contracts during the three and nine months ended September 30, 2016 related to the partial ineffectiveness of the interest rate contracts. The Company will reclassify into earnings over the 10-year term of the 2.750% senior unsecured notes due 2026 as an increase to interest expense approximately $49.2 million (or approximately $4.9 million per year) of the amounts recorded in the consolidated balance sheets within accumulated other comprehensive loss, which represents the effective portion of the applicable interest rate contracts. As of September 30, 2016 , 767 Fifth Partners LLC, which is a subsidiary of the consolidated entity in which the Company has a 60% interest and owns 767 Fifth Avenue (the General Motors Building) in New York City, had entered into sixteen forward-starting interest rate swap contracts (including two contracts entered into during the nine months ended September 30, 2016 with notional amounts aggregating $50.0 million ) that fix the 10 -year swap rate at a weighted-average rate of approximately 2.619% per annum on notional amounts aggregating $450.0 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. 767 Fifth Avenue Partners LLC’s interest rate swap contracts consisted of the following at September 30, 2016 (dollars in thousands): Derivative Instrument Aggregate Notional Amount Effective Date Maturity Date Strike Rate Range Balance Sheet Location Fair Value Low High 767 Fifth Partners LLC: Interest Rate Swaps $ 450,000 June 7, 2017 June 7, 2027 2.336 % - 2.950 % Other Liabilities $ (46,405 ) 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. 767 Fifth Partners LLC 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 September 30, 2016 , the fair value of 767 Fifth Partners LLC’s derivatives is in a liability position, excluding any adjustment for nonperformance risk and excluding accrued interest, related to these agreements of approximately $46.5 million . As of September 30, 2016 , 767 Fifth Partners LLC has not posted any collateral related to these agreements. If 767 Fifth Partners LLC had breached any of these provisions at September 30, 2016 , it could have been required to settle its obligations under the agreements at their termination value of approximately $46.5 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. The Company classifies cash flows related to derivative instruments within its Consolidated Statements of Cash Flows consistent with the nature of the hedged item. 767 Fifth Partners LLC has recorded the changes in fair value of the swap contracts related to the effective portion of the interest rate contracts aggregating approximately $46.4 million in Other Liabilities and Accumulated Other Comprehensive Loss within the Company’s Consolidated Balance Sheets. During the nine months ended September 30, 2016 , 767 Fifth Partners LLC did not record any hedge ineffectiveness. 767 Fifth Partners LLC expects that within the next twelve months it will reclassify into earnings as an increase to interest expense approximately $1.5 million of the amounts recorded within Accumulated Other Comprehensive Loss relating to the forward-starting interest rate swap contracts in effect and as of September 30, 2016 . The following table presents the location in the financial statements of the losses recognized related to the Company’s cash flow hedges for the three and nine months ended September 30, 2016 and 2015 : Three months ended September 30, Nine months ended September 30, 2016 2015 2016 2015 (in thousands) Amount of gain (loss) related to the effective portion recognized in other comprehensive loss $ 5,712 $ (30,156 ) $ (85,285 ) $ (18,050 ) Amount of loss related to the effective portion subsequently reclassified to earnings $ (1,190 ) $ (627 ) $ (2,445 ) $ (1,882 ) Amount of loss related to the ineffective portion and amount excluded from effectiveness testing $ (140 ) $ — $ (140 ) $ — Boston Properties, Inc. The following table reflects the changes in accumulated other comprehensive loss for the nine months ended September 30, 2016 and 2015 (in thousands): Balance at December 31, 2015 $ (14,114 ) Effective portion of interest rate contracts (85,285 ) Amortization of interest rate contracts 2,445 Other comprehensive loss attributable to noncontrolling interests 23,011 Balance at September 30, 2016 $ (73,943 ) Balance at December 31, 2014 $ (9,304 ) Effective portion of interest rate contracts (18,050 ) Amortization of interest rate contracts 1,882 Other comprehensive loss attributable to noncontrolling interests 4,847 Balance at September 30, 2015 $ (20,625 ) Boston Properties Limited Partnership The following table reflects the changes in accumulated other comprehensive loss for the nine months ended September 30, 2016 and 2015 (in thousands): Balance at December 31, 2015 $ (18,337 ) Effective portion of interest rate contracts (85,285 ) Amortization of interest rate contracts 2,445 Other comprehensive loss attributable to noncontrolling interests 16,134 Balance at September 30, 2016 $ (85,043 ) Balance at December 31, 2014 $ (12,973 ) Effective portion of interest rate contracts (18,050 ) Amortization of interest rate contracts 1,882 Other comprehensive loss attributable to noncontrolling interests 3,540 Balance at September 30, 2015 $ (25,601 )

Commitments And Contingencies

Commitments And Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	8. 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 related to lender and development requirements that total approximately $14.0 million . 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. 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 joint venture entity, 767 Venture, LLC, the Company guaranteed the consolidated joint venture’s obligation to fund various escrows, including tenant improvements, taxes and insurance in lieu of cash deposits. As of September 30, 2016 , the maximum funding obligation under the guarantee was approximately $14.5 million . The Company earns a fee from the joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee. In connection with 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 joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee. From time to time, the Company (or the applicable joint venture) has also agreed to guarantee portions of the principal, interest or other amounts in connection with other unconsolidated joint venture borrowings. In addition to the financial guarantees referenced above, the Company has agreed to customary environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, misrepresentation and bankruptcy) on certain of its unconsolidated joint venture loans. 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 . During 2014, the Company received a distribution of approximately $7.7 million . On March 11, 2015, the Company received a second interim distribution totaling approximately $4.5 million , which is included in Base Rent in the Consolidated Statements of Operations for the nine months ended September 30, 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 Consolidated Statements of Operations for the three and nine months ended September 30, 2015. On July 5, 2016, the Company received a fourth interim distribution totaling approximately $1.4 million , which is included in Base Rent in the Consolidated Statements of Operations for the nine months ended September 30, 2016, leaving a remaining claim of approximately $28.0 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 September 30, 2016 . Insurance The Company carries insurance coverage on its properties, including those under development, of types and in amounts and with deductibles that it believes are in line with coverage customarily obtained by owners of similar properties. Certain properties owned in joint ventures with third parties are insured by the third party partner with insurance coverage of types and in amounts and with deductibles the Company 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 our portfolio, including 767 Fifth Avenue, but excluding certain other properties owned in joint ventures with third parties or which the Company manages. The per occurrence limit for NBCR Coverage is $1.0 billion . Under TRIA, after the payment of the required deductible and coinsurance, the 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 2016, the program trigger is $120 million and the coinsurance is 16% , 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 3% of the value of the affected property. Specifically, the Company currently carries earthquake insurance which covers its San Francisco and Los Angeles regions (excluding Salesforce Tower) with a $170 million per occurrence limit, and a $170 million annual aggregate limit, $20 million of which is provided by IXP, as a direct insurer. The builders risk policy maintained for the development of 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 and Los Angeles 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.

Noncontrolling Interests

Noncontrolling Interests	9 Months Ended
	Sep. 30, 2016
Noncontrolling Interest [Abstract]
Noncontrolling Interests	9. 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 September 30, 2016 , the noncontrolling interests in Boston Properties Limited Partnership consisted of 17,096,675 OP Units, 905,494 LTIP Units (including 166,629 2012 OPP Units and 93,928 2013 MYLTIP Units), 474,415 2014 MYLTIP Units, 367,218 2015 MYLTIP Units and 473,360 2016 MYLTIP Units held by parties other than Boston Properties, Inc. Noncontrolling Interest—Redeemable Preferred Units 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 the security interest was released. 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. The following table reflects the activity of the noncontrolling interests—redeemable preferred units for the nine months ended September 30, 2015 (in thousands): Balance at December 31, 2014 $ 633 Net income 6 Distributions (6 ) Redemption of redeemable preferred units (Series Four Preferred Units) (633 ) Balance at September 30, 2015 $ — Noncontrolling Interest—Redeemable Interest in Property Partnership On October 4, 2012 , the Company completed the formation of a joint venture that 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 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 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 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 entity for the nine months ended September 30, 2015 (in thousands): 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 September 30, 2015 $ — Noncontrolling Interest—Common Units During the nine months ended September 30, 2016 , 173,694 OP Units were presented by the holders for redemption (including 86,684 OP Units issued upon conversion of LTIP Units, 2012 OPP Units and 2013 MYLTIP Units) and were redeemed by Boston Properties, Inc. in exchange for an equal number of shares of Common Stock. Boston Properties Limited Partnership exercised its right under the terms of its partnership agreement to convert an aggregate of 625,043 eligible LTIP Units (including an aggregate of 32,349 2012 OPP Units and 2013 MYLTIP Units) into Common Units effective as of May 2, 2016. These conversions were effected solely for administrative efficiency and had no substantive impact on the rights of Boston Properties Limited Partnership or the holders of these LTIP Units, as the economic and other rights of the LTIP Units converted were substantively identical to those of the Common Units. In the future, Boston Properties Limited Partnership intends to convert LTIP Units (including 2012 OPP Units and MYLTIP Units) into Common Units promptly after they become eligible for conversion. The May 2016 conversions were, and future conversions will be, effected at the election of Boston Properties Limited Partnership and are without regard to the investment intentions of the holders of the units. At September 30, 2016 , Boston Properties Limited Partnership had outstanding 474,415 2014 MYLTIP Units, 367,218 2015 MYLTIP Units and 473,360 2016 MYLTIP Units. Prior to the applicable measurement date (February 3, 2017 for 2014 MYLTIP Units, February 4, 2018 for 2015 MYLTIP Units and February 9, 2019 for 2016 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 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 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 . As a result, 205,762 2013 MYLTIP Units were automatically forfeited. The following table presents Boston Properties Limited Partnership’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units and, after the February 4, 2016 measurement date, the 2013 MYLTIP Units) and its distributions on the 2013 MYLTIP Units (prior to the February 4, 2016 measurement date), 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units (after the February 10, 2016 issuance date) paid in 2016: Record Date Payment Date Distributions per OP Unit and LTIP Unit Distributions per MYLTIP Unit September 30, 2016 October 31, 2016 $0.65 $0.065 June 30, 2016 July 29, 2016 $0.65 $0.065 March 31, 2016 April 29, 2016 $0.65 $0.065 December 31, 2015 January 28, 2016 $1.90 (1) $0.065 _______________ (1) Includes a special distribution of $1.25 per unit. A holder of an OP Unit may present the 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 the 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 LTIP Units (including the 2012 OPP Units and 2013 MYLTIP Units) assuming that all conditions had been met for the conversion thereof had all of such units been redeemed at September 30, 2016 was approximately $2.5 billion based on the last reported price of a share of Common Stock on the New York Stock Exchange of $136.29 per share on September 30, 2016 . Boston Properties Limited Partnership The following table reflects the activity of noncontrolling interests—redeemable common units of Boston Properties Limited Partnership for the nine months ended September 30, 2016 and 2015 (in thousands): Balance at December 31, 2015 $ 2,286,689 Contributions 31,492 Net income 42,120 Distributions (35,500 ) Conversion of redeemable partnership units (5,881 ) Unearned compensation (10,072 ) Accumulated other comprehensive loss (6,877 ) Adjustment to reflect redeemable partnership units at redemption value 151,545 Balance at September 30, 2016 $ 2,453,516 Balance at December 31, 2014 $ 2,310,046 Contributions 39,036 Net income 50,906 Distributions (35,307 ) Conversion of redeemable partnership units (14,157 ) Unearned compensation (9,729 ) Accumulated other comprehensive loss (1,307 ) Adjustment to reflect redeemable partnership units at redemption value (216,037 ) Balance at September 30, 2015 $ 2,123,451 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 $1.5 billion at September 30, 2016 and approximately $1.6 billion at December 31, 2015 , are included in Noncontrolling Interests—Property Partnerships in the accompanying 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. 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. On May 12, 2016, the partners in the Company’s consolidated entity that owns Salesforce Tower located in San Francisco, California amended the venture agreement. Under the venture agreement, if the Company elects to fund the construction of Salesforce Tower without a construction loan (or a construction loan of less than 50% of project costs) and the venture has commenced vertical construction of the project, then the partner’s capital funding obligation shall be limited, in which event the Company shall fund up to 2.5% of the total project costs (i.e., 50% of the partner’s 5% interest in the venture) in the form of a loan to the partner. This loan would bear interest at the then prevailing market interest rates for construction loans. Under the amended agreement, the partners have agreed to structure this funding by the Company as preferred equity rather than a loan. The preferred equity contributed by the Company shall earn a preferred return equal to LIBOR plus 3.00% per annum and shall be payable to the Company out of any distributions to which the partner would otherwise be entitled until such preferred equity and preferred return have been repaid to the Company. As of September 30, 2016, approximately $2.0 million of preferred equity had been contributed by the Company to the venture. The following table reflects the activity of the noncontrolling interests in property partnerships for the nine months ended September 30, 2016 and 2015 (in thousands): Balance at December 31, 2015 $ 1,574,400 Capital contributions 5,417 Net income 53 Accumulated other comprehensive loss (16,134 ) Distributions (38,694 ) Balance at September 30, 2016 $ 1,525,042 Balance at December 31, 2014 $ 1,602,467 Capital contributions 1,758 Net income 134,591 Accumulated other comprehensive loss (3,540 ) Distributions (144,468 ) Balance at September 30, 2015 $ 1,590,808

Stockholders' Equity _ Partners

Stockholders' Equity / Partners' Capital	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Stockholders' Equity / Partners' Capital	10. Stockholders’ Equity / Partners’ Capital As of September 30, 2016 , Boston Properties, Inc. had 153,773,012 shares of Common Stock outstanding. As of September 30, 2016 , Boston Properties, Inc. owned 1,717,752 general partnership units and 152,055,260 limited partnership units of Boston Properties Limited Partnership. 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 since its inception. During the nine months ended September 30, 2016 , Boston Properties, Inc. issued 173,694 shares of Common Stock in connection with the redemption of an equal number of redeemable OP Units from third parties. The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per OP Unit and LTIP Unit paid in 2016: Record Date Payment Date Dividend (Per Share) Distribution (Per Unit) September 30, 2016 October 31, 2016 $0.65 $0.65 June 30, 2016 July 29, 2016 $0.65 $0.65 March 31, 2016 April 29, 2016 $0.65 $0.65 December 31, 2015 January 28, 2016 $1.90 (1) $1.90 (1) _______________ (1) Includes a special dividend/distribution of $1.25 per share/OP Unit and LTIP Unit. Preferred Stock As of September 30, 2016 , 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. 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 paid during 2016: Record Date Payment Date Dividend (Per Share) November 4, 2016 November 15, 2016 $32.8125 August 5, 2016 August 15, 2016 $32.8125 May 5, 2016 May 16, 2016 $32.8125 February 5, 2016 February 16, 2016 $32.8125

Earnings Per Share _ Common Uni

Earnings Per Share / Common Unit	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share / Common Unit	11. 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. 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 the Company, LTIP Units, 2012 OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic EPS of the Company using the two -class method. Participating securities are included in the computation of diluted EPS of the Company using the if-converted method if the impact is dilutive. Because the 2012 OPP Units and 2013 MYLTIP Units required and the 2014-2016 MYLTIP Units require the Company to outperform absolute and relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, the Company excludes such units from the diluted EPS calculation. Other potentially dilutive common shares, including stock options, restricted stock and other securities of Boston Properties Limited Partnership that are exchangeable for the Boston Properties, Inc.’s Common Stock, and the related impact on earnings, are considered when calculating diluted EPS. Three Months Ended September 30, 2016 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 $ 76,753 153,754 $ 0.50 Effect of Dilutive Securities: Stock Based Compensation — 382 — Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 76,753 154,136 $ 0.50 Three Months Ended September 30, 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 $ 184,082 153,595 $ 1.20 Allocation of undistributed earnings to participating securities (221 ) — — Net income attributable to Boston Properties, Inc. common shareholders $ 183,861 153,595 $ 1.20 Effect of Dilutive Securities: Stock Based Compensation — 191 — Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 183,861 153,786 $ 1.20 Nine Months Ended September 30, 2016 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 $ 355,114 153,681 $ 2.31 Allocation of undistributed earnings to participating securities (189 ) — — Net income attributable to Boston Properties, Inc. common shareholders $ 354,925 153,681 $ 2.31 Effect of Dilutive Securities: Stock Based Compensation — 290 — Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 354,925 153,971 $ 2.31 Nine Months Ended September 30, 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 $ 434,702 153,426 $ 2.83 Allocation of undistributed earnings to participating securities (361 ) — — Net income attributable to Boston Properties, Inc. common shareholders $ 434,341 153,426 $ 2.83 Effect of Dilutive Securities: Stock Based Compensation — 399 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 434,341 153,825 $ 2.82 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. 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, 2012 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 2012 OPP Units and 2013 MYLTIP Units required and the 2014-2016 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 17,625,000 and 17,565,000 redeemable common units for the three months ended September 30, 2016 and 2015 , respectively, and approximately 17,672,000 and 17,705,000 redeemable common units for the nine months ended September 30, 2016 and 2015 , respectively. Three Months Ended September 30, 2016 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 $ 91,306 171,379 $ 0.53 Effect of Dilutive Securities: Stock Based Compensation — 382 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 91,306 171,761 $ 0.53 Three Months Ended September 30, 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 $ 207,626 171,160 $ 1.21 Allocation of undistributed earnings to participating securities (246 ) — — Net income attributable to Boston Properties Limited Partnership common unitholders $ 207,380 171,160 $ 1.21 Effect of Dilutive Securities: Stock Based Compensation — 191 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 207,380 171,351 $ 1.21 Nine Months Ended September 30, 2016 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 $ 408,540 171,353 $ 2.38 Allocation of undistributed earnings to participating securities (210 ) — — Net income attributable to Boston Properties Limited Partnership common unitholders $ 408,330 171,353 $ 2.38 Effect of Dilutive Securities: Stock Based Compensation — 290 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 408,330 171,643 $ 2.38 Nine Months Ended September 30, 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 $ 491,847 171,131 $ 2.87 Allocation of undistributed earnings to participating securities (402 ) — — Net income attributable to Boston Properties Limited Partnership common unitholders $ 491,445 171,131 $ 2.87 Effect of Dilutive Securities: Stock Based Compensation — 399 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 491,445 171,530 $ 2.87

Stock Option and Incentive Plan

Stock Option and Incentive Plan	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option and Incentive Plan	12. Stock Option and Incentive Plan On January 25, 2016, Boston Properties Inc.’s Compensation Committee approved the 2016 MYLTIP awards under Boston Properties Inc.’s 2012 Stock Option and Incentive Plan (the “2012 Plan”) to certain officers and employees of Boston Properties, Inc. The 2016 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 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 OP Units and no special distributions. Under the FASB’s ASC 718 “Compensation-Stock Compensation,” 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 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 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 . As a result, 205,762 2013 MYLTIP Units were automatically forfeited. During the nine months ended September 30, 2016 , Boston Properties, Inc. issued 22,067 shares of restricted common stock and Boston Properties Limited Partnership issued 147,872 LTIP Units and 475,004 2016 MYLTIP Units to employees and non-employee directors under the 2012 Plan. Employees and non-employee directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit and 2016 MYLTIP Unit. When issued, LTIP Units are not economically equivalent in value to a share of Common Stock, but over time can increase in value to one-for-one parity with Common Stock if there is sufficient appreciation in the value of the Company’s assets. 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. The shares of restricted stock granted during the nine months ended September 30, 2016 were valued at approximately $2.5 million ( $113.51 per share weighted-average). The LTIP Units granted were valued at approximately $15.4 million ( $103.83 per unit weighted-average fair value) using a Monte Carlo simulation method model. The per unit fair values of the LTIP Units granted were estimated on the dates of grant and for a substantial majority of such units were valued using the following assumptions: an expected life of 5.7 years , a risk-free interest rate of 1.61% and an expected price volatility of 33% . As the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units are subject to both a service condition and a market condition, the Company recognizes the compensation expense related to the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units under the graded vesting attribution method. Under the graded vesting attribution method, each portion of the award that vests at a different date is accounted for as a separate award and recognized over the period appropriate to that portion so that the compensation cost for each portion should be recognized in full by the time that portion vests. Dividends paid on both vested and unvested shares of restricted stock are charged directly to Dividends in Excess of Earnings in 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, 2015 MYLTIP Units and 2016 MYLTIP Units was approximately $7.1 million and $5.9 million for the three months ended September 30, 2016 and 2015 , respectively, and approximately $23.6 million and $21.0 million for the nine months ended September 30, 2016 and 2015 , respectively. At September 30, 2016 , there was $22.8 million of unrecognized compensation expense related to unvested restricted stock, LTIP Units, 2012 OPP Units and 2013 MYLTIP Units and $22.9 million of unrecognized compensation expense related to unvested 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units that is expected to be recognized over a weighted-average period of approximately 2.5 years .

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Segment Information	13. Segment Information The following tables present reconciliations of Net Income Attributable to Boston Properties, Inc. Common Shareholders to Net Operating Income and Net Income Attributable to Boston Properties Limited Partnership Common Unitholders to Net Operating Income for the three and nine months ended September 30, 2016 and 2015 . Boston Properties, Inc. Three months ended September 30, Nine months ended September 30, 2016 2015 2016 2015 (in thousands) Net income attributable to Boston Properties, Inc. common shareholders $ 76,753 $ 184,082 $ 355,114 $ 434,702 Add: Preferred dividends 2,589 2,647 7,796 7,854 Noncontrolling interest—common units of the Operating Partnership 9,387 21,302 42,120 50,906 Noncontrolling interest—redeemable preferred units of the Operating Partnership — — — 6 Noncontrolling interests in property partnerships (17,225 ) 115,240 53 139,712 Losses from interest rate contracts 140 — 140 — Losses from early extinguishments of debt 371 — 371 — Interest expense 104,641 108,727 314,953 326,018 Depreciation and amortization expense 203,748 153,015 516,371 475,082 Impairment loss 1,783 — 1,783 — Transaction costs 249 254 1,187 789 General and administrative expense 25,165 20,944 79,936 72,019 Less: Gains on sales of real estate 12,983 199,479 80,606 294,563 Gains (losses) from investments in securities 976 (1,515 ) 1,713 (1,146 ) Interest and other income 3,628 3,637 6,657 6,337 Income from unconsolidated joint ventures 1,464 2,647 5,489 20,559 Development and management services income 6,364 5,912 18,586 16,102 Net Operating Income $ 382,186 $ 396,051 $ 1,206,773 $ 1,170,673 Boston Properties Limited Partnership Three months ended September 30, Nine months ended September 30, 2016 2015 2016 2015 (in thousands) Net income attributable to Boston Properties Limited Partnership common unitholders 91,306 207,626 408,540 491,847 Add: Preferred distributions 2,589 2,647 7,796 7,854 Noncontrolling interest—redeemable preferred units — — — 6 Noncontrolling interests in property partnerships (17,225 ) 115,240 53 139,712 Losses from interest rate contracts 140 — 140 — Losses from early extinguishments of debt 371 — 371 — Interest expense 104,641 108,727 314,953 326,018 Depreciation and amortization expense 198,582 151,017 507,234 469,087 Impairment loss 1,783 — 1,783 — Transaction costs 249 254 1,187 789 General and administrative expense 25,165 20,944 79,936 72,019 Less: Gains on sales of real estate 12,983 199,723 82,775 294,807 Gains (losses) from investments in securities 976 (1,515 ) 1,713 (1,146 ) Interest and other income 3,628 3,637 6,657 6,337 Income from unconsolidated joint ventures 1,464 2,647 5,489 20,559 Development and management services income 6,364 5,912 18,586 16,102 Net Operating Income $ 382,186 $ 396,051 $ 1,206,773 $ 1,170,673 Net Operating Income is not a measure of operating results or cash flows from operating activities as measured by GAAP, 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 performance 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. 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. Preferred dividends/distributions, noncontrolling interests, gains on sales of real estate, losses from interest rate contracts, losses from early extinguishments of debt, interest expense, gains (losses) from investments in securities, interest and other income, income from unconsolidated joint ventures, depreciation and amortization expense, impairment loss, transaction costs, general and administrative expenses and development and management services income are not included in Net Operating Income as internal reporting addresses these items on a corporate level. 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: Office, Residential and Hotel. Beginning on January 1, 2016, the properties that were historically included in the Company’s Office/Technical segment are now included in the Office segment to align with its method of internal reporting, which shifted after the disposition of 415 Main Street in Cambridge, Massachusetts. As such, the amounts previously included in Office/Technical are now included in Office for all periods presented. Information by geographic area and property type (dollars in thousands): For the three months ended September 30, 2016 : Boston New York San Francisco Washington, DC Total Rental Revenue: Office $ 183,975 $ 237,262 $ 80,235 $ 100,666 $ 602,138 Residential 1,227 — — 3,145 4,372 Hotel 12,354 — — — 12,354 Total 197,556 237,262 80,235 103,811 618,864 % of Grand Totals 31.92 % 38.34 % 12.96 % 16.78 % 100.00 % Rental Expenses: Office 71,254 95,073 26,037 33,973 226,337 Residential 1,141 — — 1,082 2,223 Hotel 8,118 — — — 8,118 Total 80,513 95,073 26,037 35,055 236,678 % of Grand Totals 34.02 % 40.17 % 11.00 % 14.81 % 100.00 % Net operating income $ 117,043 $ 142,189 $ 54,198 $ 68,756 $ 382,186 % of Grand Totals 30.62 % 37.21 % 14.18 % 17.99 % 100.00 % For the three months ended September 30, 2015 : Boston New York San Francisco Washington, DC Total Rental Revenue: Office $ 179,278 $ 253,612 $ 77,315 $ 97,037 $ 607,242 Residential 1,275 — — 2,836 4,111 Hotel 12,619 — — — 12,619 Total 193,172 253,612 77,315 99,873 623,972 % of Grand Totals 30.96 % 40.64 % 12.39 % 16.01 % 100.00 % Rental Expenses: Office 71,898 88,496 25,883 31,985 218,262 Residential 485 — — 1,049 1,534 Hotel 8,125 — — — 8,125 Total 80,508 88,496 25,883 33,034 227,921 % of Grand Totals 35.32 % 38.83 % 11.36 % 14.49 % 100.00 % Net operating income $ 112,664 $ 165,116 $ 51,432 $ 66,839 $ 396,051 % of Grand Totals 28.45 % 41.69 % 12.98 % 16.88 % 100.00 % For the nine months ended September 30, 2016 : Boston New York San Francisco Washington, DC Total Rental Revenue: Office $ 540,850 $ 773,077 $ 235,076 $ 300,742 $ 1,849,745 Residential 3,578 — — 8,931 12,509 Hotel 33,919 — — — 33,919 Total 578,347 773,077 235,076 309,673 1,896,173 % of Grand Totals 30.50 % 40.77 % 12.40 % 16.33 % 100.00 % Rental Expenses: Office 210,695 272,620 75,412 101,514 660,241 Residential 2,174 — — 3,255 5,429 Hotel 23,730 — — — 23,730 Total 236,599 272,620 75,412 104,769 689,400 % of Grand Totals 34.32 % 39.54 % 10.94 % 15.20 % 100.00 % Net operating income $ 341,748 $ 500,457 $ 159,664 $ 204,904 $ 1,206,773 % of Grand Totals 28.32 % 41.47 % 13.23 % 16.98 % 100.00 % For the nine months ended September 30, 2015 : Boston New York San Francisco Washington, DC Total Rental Revenue: Office $ 536,241 $ 753,142 $ 223,561 $ 287,652 $ 1,800,596 Residential 3,584 — — 11,192 14,776 Hotel 35,107 — — — 35,107 Total 574,932 753,142 223,561 298,844 1,850,479 % of Grand Totals 31.07 % 40.70 % 12.08 % 16.15 % 100.00 % Rental Expenses: Office 218,002 259,218 73,119 98,660 648,999 Residential 1,505 — — 5,106 6,611 Hotel 24,196 — — — 24,196 Total 243,703 259,218 73,119 103,766 679,806 % of Grand Totals 35.85 % 38.13 % 10.76 % 15.26 % 100.00 % Net operating income $ 331,229 $ 493,924 $ 150,442 $ 195,078 $ 1,170,673 % of Grand Totals 28.29 % 42.19 % 12.85 % 16.67 % 100.00 %

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2016
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events On October 1, 2016, a joint venture in which the Company has a 50% interest completed and fully placed in-service 1265 Main Street, a Class A office project with approximately 115,000 net rentable feet located in Waltham, Massachusetts. On October 20, 2016, the Company and its partner in the unconsolidated joint venture that owns Metropolitan Square located in Washington, DC, completed the sale of an 80% interest in the joint venture for a gross sale price of approximately $282.4 million , including the assumption by the buyer of its pro rata share of the mortgage loan collateralized by the property totaling approximately $133.4 million . In addition, the buyer has agreed to assume certain unfunded leasing costs totaling approximately $14.2 million . Prior to the sale, the Company owned a 51% interest and its partner owned a 49% interest in the joint venture. Following the sale, the Company continues to own a 20% interest in the joint venture with the buyer owning the remaining 80% . Metropolitan Square is an approximately 607,000 net rentable square foot Class A office property. On October 24, 2016, the Company entered into an option agreement that will allow it to ground lease and/or purchase real property adjacent to the MacArthur BART station located in Oakland, California, that could support the development of a 400 -unit residential building and supporting retail space. On November 7, 2016, the Company entered into a 15 -year lease with a tenant for approximately 476,500 net rentable square feet of Class A office space in a build-to-suit development project to be located at the Company's 145 Broadway property at Kendall Center in Cambridge, Massachusetts. 145 Broadway currently consists of an approximately 80,000 net rentable square foot Class A office property that will be redeveloped into an approximately 486,000 net rentable square foot Class A office property, including approximately 9,500 net rentable square feet of retail space. The commencement of the redevelopment project is subject to the receipt of the remaining necessary approvals, and the Company currently expects to begin the project in the second quarter of 2017 with the relocation of an existing tenant to another property within the Company’s portfolio. The Company expects the building will be available for occupancy by the new tenant during the fourth quarter of 2019. There can be no assurance that the project will commence or that the building will be available for occupancy on the anticipated schedule or at all.

Basis Of Presentation And Sum23

Basis Of Presentation And Summary Of Significant Accounting Policies Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2016
Recent Accounting Pronouncements [Abstract]
Recent Accounting Pronouncement [Policy Text Block]	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued ASU 2014-09, “Revenue from Contract with Customers (Topic 606)” (“ASU 2014-09”). The objective of ASU 2014-09 is to establish a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and will supersede most of the existing revenue recognition guidance, including industry-specific guidance. The core principle is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In applying ASU 2014-09, companies will perform a five-step analysis of transactions to determine when and how revenue is recognized. ASU 2014-09 applies to all contracts with customers except those that are within the scope of other topics in the FASB’s Accounting Standards Codification (“ASC”). In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date (“ASU 2015-14”), which delayed the effective date of ASU 2014-09 by one year making it effective for the first interim period within annual reporting periods beginning after December 15, 2017. Early adoption is permitted as of the original effective date. The Company is currently assessing the potential impact that the adoption of ASU 2014-09 will have on its 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 is permitted for financial statements that have not been previously issued. On January 1, 2016, the Company adopted ASU 2015-03 and retrospectively applied the guidance to its Mortgage Notes Payable and Unsecured Senior Notes for all periods presented. Unamortized deferred financing costs, which were previously included in Deferred Charges, Net, totaling approximately $2.5 million and $36.8 million are included in Mortgage Notes Payable, Net and Unsecured Senior Notes, Net, respectively, as of September 30, 2016 and approximately $3.5 million and $24.5 million are included in Mortgage Notes Payable, Net and Unsecured Senior Notes, Net, respectively, as of December 31, 2015. 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 the Company for reporting periods beginning after December 15, 2017. 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. In March 2016, the FASB issued ASU 2016-05, “Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships” (“ASU 2016-05”), which provides guidance clarifying that a novation of party to a derivative instrument, whereby one of the parties to a derivative instrument is replaced with another party, does not, in and of itself, require de-designation of that hedging relationship provided that all other hedge criteria continue to be met. ASU 2016-05 is effective for the Company for reporting periods beginning after December 15, 2016, with early adoption permitted. The Company is currently assessing the potential impact that the adoption of ASU 2016-05 will have on its consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting” (“ASU 2016-09”) . ASU 2016-09 is intended to improve the accounting for share-based payments and affects all organizations that issue share-based payment awards to their employees. Several aspects of the accounting for share-based payment awards are simplified with ASU 2016-09, including income tax consequences, classification of awards as equity or liabilities and classification on the statement of cash flows. ASU 2016-09 is effective for the Company for reporting periods beginning after December 15, 2016, with early adoption permitted. The Company is currently assessing the potential impact that the adoption of ASU 2016-09 will have on its consolidated financial statements. In May 2016, the FASB issued ASU No. 2016-12, “Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients” (“ASU 2016-12”). ASU 2016-12 is intended to clarify and provide practical expedients for certain aspects of ASU 2014-09, which outlines a single comprehensive model for entities to use in accounting for revenues arising from contracts with customers and notes that lease contracts with customers are a scope exception. The Company may elect to adopt ASU 2016-12 as of the original effective date; however, adoption is required for annual reporting periods beginning after December 15, 2017. The Company is currently assessing the potential impact that the adoption of ASU 2016-12 will have on its consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force)” (“ASU 2016-15”). ASU 2016-15 is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The areas addressed in the new guidance related to debt prepayment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned and bank-owned life insurance policies, distributions received from equity method investments, beneficial interest in securitization transactions, and separately identifiable cash flows and application of the predominance principle. ASU 2016-15 is effective for the Company for reporting periods beginning after December 15, 2017, with early adoption permitted, provided that all of the amendments are adopted in the same period. The Company is currently assessing the potential impact that the adoption of ASU 2016-15 will have on its consolidated financial statements.

Basis Of Presentation And Sum24

Basis Of Presentation And Summary Of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value	The following table presents the aggregate carrying value of the Company’s mortgage notes payable, net, mezzanine notes payable and unsecured senior notes, net and the Company’s corresponding estimate of fair value as of September 30, 2016 and December 31, 2015 (in thousands): September 30, 2016 December 31, 2015 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Mortgage notes payable, net $ 2,077,707 $ 2,111,614 $ 3,435,242 $ 3,503,746 Mezzanine notes payable 307,448 309,095 308,482 306,103 Unsecured senior notes, net 7,243,767 7,761,908 5,264,819 5,547,738 Total $ 9,628,922 $ 10,182,617 $ 9,008,543 $ 9,357,587

Real Estate Real Estate (Tables

Real Estate Real Estate (Tables)	9 Months Ended
	Sep. 30, 2016
Entity Information [Line Items]
Schedule of Real Estate Properties [Table Text Block]	Boston Properties, Inc. Real estate consisted of the following at September 30, 2016 and December 31, 2015 (in thousands): September 30, 2016 December 31, 2015 Land $ 4,879,020 $ 4,806,021 Land held for future development (1) 243,887 252,195 Buildings and improvements 11,792,853 11,709,285 Tenant improvements 2,001,259 1,920,247 Furniture, fixtures and equipment 31,724 29,852 Construction in progress 954,013 763,935 Total 19,902,756 19,481,535 Less: Accumulated depreciation (4,113,553 ) (3,925,894 ) $ 15,789,203 $ 15,555,641 _______________ (1) Includes pre-development costs.
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The following table summarizes the allocation of the aggregate purchase price of 3625-3635 Peterson Way at the date of acquisition (in thousands). Land $ 63,206 Building and improvements 7,210 Tenant improvements 7,669 In-place lease intangibles 4,262 Below-market lease intangible (4,347 ) Net assets acquired $ 78,000
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	The following table summarizes the estimated annual amortization of the acquired below-market lease intangible and the acquired in-place lease intangibles for 3625-3635 Peterson Way for the remainder of 2016 and each of the next four succeeding fiscal years (in thousands). Acquired In-Place Lease Intangibles Acquired Below- Market Lease Intangible Period from April 22, 2016 through December 31, 2016 $ 578 $ (589 ) 2017 867 (884 ) 2018 867 (884 ) 2019 867 (884 ) 2020 867 (884 )
Boston Properties Limited Partnership
Entity Information [Line Items]
Schedule of Real Estate Properties [Table Text Block]	Boston Properties Limited Partnership Real estate consisted of the following at September 30, 2016 and December 31, 2015 (in thousands): September 30, 2016 December 31, 2015 Land $ 4,774,460 $ 4,700,793 Land held for future development (1) 243,887 252,195 Buildings and improvements 11,484,022 11,394,119 Tenant improvements 2,001,259 1,920,247 Furniture, fixtures and equipment 31,724 29,852 Construction in progress 954,013 763,935 Total 19,489,365 19,061,141 Less: Accumulated depreciation (4,030,172 ) (3,846,816 ) $ 15,459,193 $ 15,214,325 _______________ (1) Includes pre-development costs.

Investments in Unconsolidated26

Investments in Unconsolidated Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2016
Schedule of Equity Method Investments [Line Items]
Investments In Unconsolidated Joint Ventures	The investments in unconsolidated joint ventures consist of the following at September 30, 2016 and December 31, 2015 : Nominal % Ownership Carrying Value of Investment (1) Entity Properties September 30, 2016 December 31, 2015 (in thousands) Square 407 Limited Partnership Market Square North 50.0 % $ (8,483 ) $ (9,951 ) The Metropolitan Square Associates LLC Metropolitan Square 51.0 % 9,552 9,179 BP/CRF 901 New York Avenue LLC 901 New York Avenue 25.0 % (2) (10,898 ) (11,958 ) WP Project Developer LLC Wisconsin Place Land and Infrastructure 33.3 % (3) 42,073 43,524 Annapolis Junction NFM, LLC Annapolis Junction 50.0 % (4) 21,075 29,009 540 Madison Venture LLC 540 Madison Avenue 60.0 % 69,602 68,983 500 North Capitol Venture LLC 500 North Capitol Street, NW 30.0 % (3,395 ) (3,292 ) 501 K Street LLC 1001 6th Street 50.0 % (5) 42,541 42,584 Podium Developer LLC The Hub on Causeway 50.0 % 33,820 18,508 1265 Main Office JV LLC 1265 Main Street 50.0 % 23,757 11,916 BNY Tower Holdings LLC (6) Dock72 at the Brooklyn Navy Yard 50.0 % 25,980 11,521 CA-Colorado Center Limited Partnership Colorado Center 49.8 % 507,259 N/A $ 752,883 $ 210,023 _______________ (1) Investments with deficit balances aggregating approximately $22.8 million and $25.2 million at September 30, 2016 and December 31, 2015 , respectively, have been reflected within Other Liabilities in 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 for this land parcel, the partner will be entitled to up to two additional payments from the venture based on increases in total entitled square footage of the project above 520,000 square feet and achieving certain project returns at stabilization. (6) The entity is a VIE (See Note 2 ).
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: September 30, 2016 December 31, 2015 (in thousands) ASSETS Real estate and development in process, net $ 1,460,808 $ 1,072,412 Other assets 294,912 252,285 Total assets $ 1,755,720 $ 1,324,697 LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY Mortgage and notes payable, net $ 826,807 $ 830,125 Other liabilities 54,390 44,549 Members’/Partners’ equity 874,523 450,023 Total liabilities and members’/partners’ equity $ 1,755,720 $ 1,324,697 Company’s share of equity $ 449,351 $ 237,070 Basis differentials (1) 303,532 (27,047 ) Carrying value of the Company’s investments in unconsolidated joint ventures (2) $ 752,883 $ 210,023 _______________ (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 result from impairments of investments, acquisitions through joint ventures with no change in control 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. At September 30, 2016, there is an aggregate basis differential of approximately $330.1 million between the carrying value of the Company’s investment in the joint venture that owns Colorado Center and the joint venture’s basis in the assets and liabilities, which differential (excluding land) shall be amortized over the remaining lives of the related assets and liabilities. (2) Investments with deficit balances aggregating approximately $22.8 million and $25.2 million at September 30, 2016 and December 31, 2015 , respectively, have been reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.
Statements Of Operations Of The Joint Ventures	The combined summarized statements of operations of the Company’s unconsolidated joint ventures are as follows: Three months ended September 30, Nine months ended September 30, 2016 2015 2016 2015 (in thousands) Total revenue (1) $ 49,002 $ 38,197 $ 125,039 $ 116,881 Expenses Operating 21,753 15,896 54,779 47,995 Depreciation and amortization 12,038 8,832 30,306 26,854 Total expenses 33,791 24,728 85,085 74,849 Operating income 15,211 13,469 39,954 42,032 Other expense Interest expense 8,400 8,019 25,172 23,985 Net income $ 6,811 $ 5,450 $ 14,782 $ 18,047 Company’s share of net income $ 3,179 $ 2,481 $ 6,830 $ 20,025 (2) Basis differential (3) (1,715 ) 166 (1,341 ) 534 Income from unconsolidated joint ventures $ 1,464 $ 2,647 $ 5,489 $ 20,559 _______________ (1) Includes straight-line rent adjustments of approximately $5.2 million and $(0.3) million for the three months ended September 30, 2016 and 2015 , respectively, and approximately $11.0 million and $1.7 million for the nine months ended September 30, 2016 and 2015 , respectively. (2) During the nine months ended September 30, 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 nine months ended September 30, 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. (3) Includes a straight-line rent adjustment of approximately $0.7 million and a net above-/below-market rent adjustment of approximately $0.5 million for the three and nine months ended September 30, 2016 .
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	The following table summarizes the allocation of the aggregate purchase price of 3625-3635 Peterson Way at the date of acquisition (in thousands). Land $ 63,206 Building and improvements 7,210 Tenant improvements 7,669 In-place lease intangibles 4,262 Below-market lease intangible (4,347 ) Net assets acquired $ 78,000
Colorado Center [Member]
Schedule of Equity Method Investments [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	Land and improvements $ 189,597 Site improvements 9,050 Building and improvements 259,592 Tenant improvements 17,234 In-place lease intangibles 43,157 Above-market lease intangible 819 Below-market lease intangible (16,461 ) Net assets $ 502,988

Unsecured Senior Notes (Tables)

Unsecured Senior Notes (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Schedule of Senior Notes	The following summarizes the unsecured senior notes outstanding as of September 30, 2016 (dollars in thousands): 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 10 Year Unsecured Senior Notes 3.650 % 3.766 % 1,000,000 February 1, 2026 10 Year Unsecured Senior Notes 2.750 % 3.495 % 1,000,000 October 1, 2026 Total principal 7,300,000 Net unamortized discount (19,429 ) Deferred financing costs, net (36,804 ) Total $ 7,243,767 _______________ (1) Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs. (2) No principal amounts are due prior to maturity.

Derivative Instruments and He28

Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]	767 Fifth Avenue Partners LLC’s interest rate swap contracts consisted of the following at September 30, 2016 (dollars in thousands): Derivative Instrument Aggregate Notional Amount Effective Date Maturity Date Strike Rate Range Balance Sheet Location Fair Value Low High 767 Fifth Partners LLC: Interest Rate Swaps $ 450,000 June 7, 2017 June 7, 2027 2.336 % - 2.950 % Other Liabilities $ (46,405 ) 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 three and nine months ended September 30, 2016 and 2015 : Three months ended September 30, Nine months ended September 30, 2016 2015 2016 2015 (in thousands) Amount of gain (loss) related to the effective portion recognized in other comprehensive loss $ 5,712 $ (30,156 ) $ (85,285 ) $ (18,050 ) Amount of loss related to the effective portion subsequently reclassified to earnings $ (1,190 ) $ (627 ) $ (2,445 ) $ (1,882 ) Amount of loss related to the ineffective portion and amount excluded from effectiveness testing $ (140 ) $ — $ (140 ) $ —
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 the nine months ended September 30, 2016 and 2015 (in thousands): Balance at December 31, 2015 $ (14,114 ) Effective portion of interest rate contracts (85,285 ) Amortization of interest rate contracts 2,445 Other comprehensive loss attributable to noncontrolling interests 23,011 Balance at September 30, 2016 $ (73,943 ) Balance at December 31, 2014 $ (9,304 ) Effective portion of interest rate contracts (18,050 ) Amortization of interest rate contracts 1,882 Other comprehensive loss attributable to noncontrolling interests 4,847 Balance at September 30, 2015 $ (20,625 ) Boston Properties Limited Partnership The following table reflects the changes in accumulated other comprehensive loss for the nine months ended September 30, 2016 and 2015 (in thousands): Balance at December 31, 2015 $ (18,337 ) Effective portion of interest rate contracts (85,285 ) Amortization of interest rate contracts 2,445 Other comprehensive loss attributable to noncontrolling interests 16,134 Balance at September 30, 2016 $ (85,043 ) Balance at December 31, 2014 $ (12,973 ) Effective portion of interest rate contracts (18,050 ) Amortization of interest rate contracts 1,882 Other comprehensive loss attributable to noncontrolling interests 3,540 Balance at September 30, 2015 $ (25,601 )

Noncontrolling Interests (Table

Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2016
Noncontrolling Interest [Line Items]
Schedule Of redeemable preferred units	The following table reflects the activity of the noncontrolling interests—redeemable preferred units for the nine months ended September 30, 2015 (in thousands): Balance at December 31, 2014 $ 633 Net income 6 Distributions (6 ) Redemption of redeemable preferred units (Series Four Preferred Units) (633 ) Balance at September 30, 2015 $ —
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 entity for the nine months ended September 30, 2015 (in thousands): 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 September 30, 2015 $ —
Distributions Declared to OP, LTIP, OPP and MYLTIP Units [Table Text Block]	The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per OP Unit and LTIP Unit paid in 2016: Record Date Payment Date Dividend (Per Share) Distribution (Per Unit) September 30, 2016 October 31, 2016 $0.65 $0.65 June 30, 2016 July 29, 2016 $0.65 $0.65 March 31, 2016 April 29, 2016 $0.65 $0.65 December 31, 2015 January 28, 2016 $1.90 (1) $1.90 (1) _______________ (1) Includes a special dividend/distribution of $1.25 per share/OP Unit and LTIP Unit.
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 nine months ended September 30, 2016 and 2015 (in thousands): Balance at December 31, 2015 $ 2,286,689 Contributions 31,492 Net income 42,120 Distributions (35,500 ) Conversion of redeemable partnership units (5,881 ) Unearned compensation (10,072 ) Accumulated other comprehensive loss (6,877 ) Adjustment to reflect redeemable partnership units at redemption value 151,545 Balance at September 30, 2016 $ 2,453,516 Balance at December 31, 2014 $ 2,310,046 Contributions 39,036 Net income 50,906 Distributions (35,307 ) Conversion of redeemable partnership units (14,157 ) Unearned compensation (9,729 ) Accumulated other comprehensive loss (1,307 ) Adjustment to reflect redeemable partnership units at redemption value (216,037 ) Balance at September 30, 2015 $ 2,123,451
Schedule Of Noncontrolling Interest Property Partnerships [Table Text Block]	The following table reflects the activity of the noncontrolling interests in property partnerships for the nine months ended September 30, 2016 and 2015 (in thousands): Balance at December 31, 2015 $ 1,574,400 Capital contributions 5,417 Net income 53 Accumulated other comprehensive loss (16,134 ) Distributions (38,694 ) Balance at September 30, 2016 $ 1,525,042 Balance at December 31, 2014 $ 1,602,467 Capital contributions 1,758 Net income 134,591 Accumulated other comprehensive loss (3,540 ) Distributions (144,468 ) Balance at September 30, 2015 $ 1,590,808
Noncontrolling Interests [Member]
Noncontrolling Interest [Line Items]
Distributions Declared to OP, LTIP, OPP and MYLTIP Units [Table Text Block]	The following table presents Boston Properties Limited Partnership’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units and, after the February 4, 2016 measurement date, the 2013 MYLTIP Units) and its distributions on the 2013 MYLTIP Units (prior to the February 4, 2016 measurement date), 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units (after the February 10, 2016 issuance date) paid in 2016: Record Date Payment Date Distributions per OP Unit and LTIP Unit Distributions per MYLTIP Unit September 30, 2016 October 31, 2016 $0.65 $0.065 June 30, 2016 July 29, 2016 $0.65 $0.065 March 31, 2016 April 29, 2016 $0.65 $0.065 December 31, 2015 January 28, 2016 $1.90 (1) $0.065 _______________ (1) Includes a special distribution of $1.25 per unit.

Stockholders' Equity _ Partne30

Stockholders' Equity / Partners' Capital Tables (Tables)	9 Months Ended
	Sep. 30, 2016
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 OP Unit and LTIP Unit paid in 2016: Record Date Payment Date Dividend (Per Share) Distribution (Per Unit) September 30, 2016 October 31, 2016 $0.65 $0.65 June 30, 2016 July 29, 2016 $0.65 $0.65 March 31, 2016 April 29, 2016 $0.65 $0.65 December 31, 2015 January 28, 2016 $1.90 (1) $1.90 (1) _______________ (1) Includes a special dividend/distribution of $1.25 per share/OP Unit and LTIP Unit.
Series B Cumulative Redeemable 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 paid during 2016: Record Date Payment Date Dividend (Per Share) November 4, 2016 November 15, 2016 $32.8125 August 5, 2016 August 15, 2016 $32.8125 May 5, 2016 May 16, 2016 $32.8125 February 5, 2016 February 16, 2016 $32.8125

Earnings Per Share _ Common U31

Earnings Per Share / Common Unit (Tables)	9 Months Ended
	Sep. 30, 2016
Entity Information [Line Items]
Computation Of Basic And Diluted Earnings Per Share	Three Months Ended September 30, 2016 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 $ 76,753 153,754 $ 0.50 Effect of Dilutive Securities: Stock Based Compensation — 382 — Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 76,753 154,136 $ 0.50 Three Months Ended September 30, 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 $ 184,082 153,595 $ 1.20 Allocation of undistributed earnings to participating securities (221 ) — — Net income attributable to Boston Properties, Inc. common shareholders $ 183,861 153,595 $ 1.20 Effect of Dilutive Securities: Stock Based Compensation — 191 — Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 183,861 153,786 $ 1.20 Nine Months Ended September 30, 2016 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 $ 355,114 153,681 $ 2.31 Allocation of undistributed earnings to participating securities (189 ) — — Net income attributable to Boston Properties, Inc. common shareholders $ 354,925 153,681 $ 2.31 Effect of Dilutive Securities: Stock Based Compensation — 290 — Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 354,925 153,971 $ 2.31 Nine Months Ended September 30, 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 $ 434,702 153,426 $ 2.83 Allocation of undistributed earnings to participating securities (361 ) — — Net income attributable to Boston Properties, Inc. common shareholders $ 434,341 153,426 $ 2.83 Effect of Dilutive Securities: Stock Based Compensation — 399 (0.01 ) Diluted Earnings: Net income attributable to Boston Properties, Inc. common shareholders $ 434,341 153,825 $ 2.82
Boston Properties Limited Partnership
Entity Information [Line Items]
Computation Of Basic And Diluted Earnings Per Share	Three Months Ended September 30, 2016 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 $ 91,306 171,379 $ 0.53 Effect of Dilutive Securities: Stock Based Compensation — 382 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 91,306 171,761 $ 0.53 Three Months Ended September 30, 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 $ 207,626 171,160 $ 1.21 Allocation of undistributed earnings to participating securities (246 ) — — Net income attributable to Boston Properties Limited Partnership common unitholders $ 207,380 171,160 $ 1.21 Effect of Dilutive Securities: Stock Based Compensation — 191 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 207,380 171,351 $ 1.21 Nine Months Ended September 30, 2016 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 $ 408,540 171,353 $ 2.38 Allocation of undistributed earnings to participating securities (210 ) — — Net income attributable to Boston Properties Limited Partnership common unitholders $ 408,330 171,353 $ 2.38 Effect of Dilutive Securities: Stock Based Compensation — 290 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 408,330 171,643 $ 2.38 Nine Months Ended September 30, 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 $ 491,847 171,131 $ 2.87 Allocation of undistributed earnings to participating securities (402 ) — — Net income attributable to Boston Properties Limited Partnership common unitholders $ 491,445 171,131 $ 2.87 Effect of Dilutive Securities: Stock Based Compensation — 399 — Diluted Earnings: Net income attributable to Boston Properties Limited Partnership common unitholders $ 491,445 171,530 $ 2.87

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Schedule Of Reconciliation Of Net Operating Income To Net Income	Boston Properties, Inc. Three months ended September 30, Nine months ended September 30, 2016 2015 2016 2015 (in thousands) Net income attributable to Boston Properties, Inc. common shareholders $ 76,753 $ 184,082 $ 355,114 $ 434,702 Add: Preferred dividends 2,589 2,647 7,796 7,854 Noncontrolling interest—common units of the Operating Partnership 9,387 21,302 42,120 50,906 Noncontrolling interest—redeemable preferred units of the Operating Partnership — — — 6 Noncontrolling interests in property partnerships (17,225 ) 115,240 53 139,712 Losses from interest rate contracts 140 — 140 — Losses from early extinguishments of debt 371 — 371 — Interest expense 104,641 108,727 314,953 326,018 Depreciation and amortization expense 203,748 153,015 516,371 475,082 Impairment loss 1,783 — 1,783 — Transaction costs 249 254 1,187 789 General and administrative expense 25,165 20,944 79,936 72,019 Less: Gains on sales of real estate 12,983 199,479 80,606 294,563 Gains (losses) from investments in securities 976 (1,515 ) 1,713 (1,146 ) Interest and other income 3,628 3,637 6,657 6,337 Income from unconsolidated joint ventures 1,464 2,647 5,489 20,559 Development and management services income 6,364 5,912 18,586 16,102 Net Operating Income $ 382,186 $ 396,051 $ 1,206,773 $ 1,170,673 Boston Properties Limited Partnership Three months ended September 30, Nine months ended September 30, 2016 2015 2016 2015 (in thousands) Net income attributable to Boston Properties Limited Partnership common unitholders 91,306 207,626 408,540 491,847 Add: Preferred distributions 2,589 2,647 7,796 7,854 Noncontrolling interest—redeemable preferred units — — — 6 Noncontrolling interests in property partnerships (17,225 ) 115,240 53 139,712 Losses from interest rate contracts 140 — 140 — Losses from early extinguishments of debt 371 — 371 — Interest expense 104,641 108,727 314,953 326,018 Depreciation and amortization expense 198,582 151,017 507,234 469,087 Impairment loss 1,783 — 1,783 — Transaction costs 249 254 1,187 789 General and administrative expense 25,165 20,944 79,936 72,019 Less: Gains on sales of real estate 12,983 199,723 82,775 294,807 Gains (losses) from investments in securities 976 (1,515 ) 1,713 (1,146 ) Interest and other income 3,628 3,637 6,657 6,337 Income from unconsolidated joint ventures 1,464 2,647 5,489 20,559 Development and management services income 6,364 5,912 18,586 16,102 Net Operating Income $ 382,186 $ 396,051 $ 1,206,773 $ 1,170,673
Schedule Of Segment Information By Geographic Area And Property Type	Information by geographic area and property type (dollars in thousands): For the three months ended September 30, 2016 : Boston New York San Francisco Washington, DC Total Rental Revenue: Office $ 183,975 $ 237,262 $ 80,235 $ 100,666 $ 602,138 Residential 1,227 — — 3,145 4,372 Hotel 12,354 — — — 12,354 Total 197,556 237,262 80,235 103,811 618,864 % of Grand Totals 31.92 % 38.34 % 12.96 % 16.78 % 100.00 % Rental Expenses: Office 71,254 95,073 26,037 33,973 226,337 Residential 1,141 — — 1,082 2,223 Hotel 8,118 — — — 8,118 Total 80,513 95,073 26,037 35,055 236,678 % of Grand Totals 34.02 % 40.17 % 11.00 % 14.81 % 100.00 % Net operating income $ 117,043 $ 142,189 $ 54,198 $ 68,756 $ 382,186 % of Grand Totals 30.62 % 37.21 % 14.18 % 17.99 % 100.00 % For the three months ended September 30, 2015 : Boston New York San Francisco Washington, DC Total Rental Revenue: Office $ 179,278 $ 253,612 $ 77,315 $ 97,037 $ 607,242 Residential 1,275 — — 2,836 4,111 Hotel 12,619 — — — 12,619 Total 193,172 253,612 77,315 99,873 623,972 % of Grand Totals 30.96 % 40.64 % 12.39 % 16.01 % 100.00 % Rental Expenses: Office 71,898 88,496 25,883 31,985 218,262 Residential 485 — — 1,049 1,534 Hotel 8,125 — — — 8,125 Total 80,508 88,496 25,883 33,034 227,921 % of Grand Totals 35.32 % 38.83 % 11.36 % 14.49 % 100.00 % Net operating income $ 112,664 $ 165,116 $ 51,432 $ 66,839 $ 396,051 % of Grand Totals 28.45 % 41.69 % 12.98 % 16.88 % 100.00 % For the nine months ended September 30, 2016 : Boston New York San Francisco Washington, DC Total Rental Revenue: Office $ 540,850 $ 773,077 $ 235,076 $ 300,742 $ 1,849,745 Residential 3,578 — — 8,931 12,509 Hotel 33,919 — — — 33,919 Total 578,347 773,077 235,076 309,673 1,896,173 % of Grand Totals 30.50 % 40.77 % 12.40 % 16.33 % 100.00 % Rental Expenses: Office 210,695 272,620 75,412 101,514 660,241 Residential 2,174 — — 3,255 5,429 Hotel 23,730 — — — 23,730 Total 236,599 272,620 75,412 104,769 689,400 % of Grand Totals 34.32 % 39.54 % 10.94 % 15.20 % 100.00 % Net operating income $ 341,748 $ 500,457 $ 159,664 $ 204,904 $ 1,206,773 % of Grand Totals 28.32 % 41.47 % 13.23 % 16.98 % 100.00 % For the nine months ended September 30, 2015 : Boston New York San Francisco Washington, DC Total Rental Revenue: Office $ 536,241 $ 753,142 $ 223,561 $ 287,652 $ 1,800,596 Residential 3,584 — — 11,192 14,776 Hotel 35,107 — — — 35,107 Total 574,932 753,142 223,561 298,844 1,850,479 % of Grand Totals 31.07 % 40.70 % 12.08 % 16.15 % 100.00 % Rental Expenses: Office 218,002 259,218 73,119 98,660 648,999 Residential 1,505 — — 5,106 6,611 Hotel 24,196 — — — 24,196 Total 243,703 259,218 73,119 103,766 679,806 % of Grand Totals 35.85 % 38.13 % 10.76 % 15.26 % 100.00 % Net operating income $ 331,229 $ 493,924 $ 150,442 $ 195,078 $ 1,170,673 % of Grand Totals 28.29 % 42.19 % 12.85 % 16.67 % 100.00 %

Organization (Details)

Organization (Details) ft² in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2016ft²Real_Estate_Propertiesseriesyrshares	Dec. 31, 2015shares
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 | series	1
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	174
Net Rentable Area (in sf) | ft²	47.7
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	8
Net Rentable Area (in sf) | ft²	4
Total Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	164
Office Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	6
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 [Member]
Real Estate Properties [Line Items]
Ratio of depository shares to shares of Series B Preferred Stock	0.01
Series B, Shares Outstanding (in shares) | shares	80,000	80,000
Series B, Dividend Rate, Percentage	5.25%
Depository shares of Series B Cumulative Redeemable Preferred [Member]
Real Estate Properties [Line Items]
Series B, Shares Outstanding (in shares) | shares	8,000,000
Series B Preferred Units [Member]
Real Estate Properties [Line Items]
Series B, Shares Outstanding (in shares) | shares	80,000
Boston Properties Inc
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)	89.50%	89.50%

Basis Of Presentation And Sum34

Basis Of Presentation And Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Mortgages [Member]
Debt Instrument [Line Items]
Deferred Finance Costs, Net	$ 2.5	$ 3.5
Unsecured Debt [Member]
Debt Instrument [Line Items]
Deferred Finance Costs, Net	$ 36.8	$ 24.5

Basis Of Presentation And Sum35

Basis Of Presentation And Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	$ 2,077,707	$ 3,435,242
Mezzanine notes payable	307,448	308,482
Unsecured senior notes, net	7,243,767	5,264,819
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	2,111,614	3,503,746
Mezzanine notes payable	309,095	306,103
Unsecured senior notes, net	7,761,908	5,547,738
Total	10,182,617	9,357,587
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Mortgage notes payable, net	2,077,707	3,435,242
Mezzanine notes payable	307,448	308,482
Unsecured senior notes, net	7,243,767	5,264,819
Total	$ 9,628,922	$ 9,008,543

Real Estate Real Estate Propert

Real Estate Real Estate Properties Table (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Land		$ 4,879,020	$ 4,806,021
Land held for future development	[1]	243,887	252,195
Buildings and improvements		11,792,853	11,709,285
Tenant improvements		2,001,259	1,920,247
Furniture, fixtures and equipment		31,724	29,852
Construction in Progress		954,013	763,935
Total		19,902,756	19,481,535
Accumulated depreciation		(4,113,553)	(3,925,894)
Total real estate		15,789,203	15,555,641
Boston Properties Limited Partnership
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Land		4,774,460	4,700,793
Land held for future development	[1]	243,887	252,195
Buildings and improvements		11,484,022	11,394,119
Tenant improvements		2,001,259	1,920,247
Furniture, fixtures and equipment		31,724	29,852
Construction in Progress		954,013	763,935
Total		19,489,365	19,061,141
Accumulated depreciation		(4,030,172)	(3,846,816)
Total real estate		$ 15,459,193	$ 15,214,325
[1]	Includes pre-development costs.

Real Estate (Narrative) (Detail

Real Estate (Narrative) (Details)	Aug. 19, 2016USD ($)ft²	Aug. 16, 2016USD ($)	Feb. 03, 2016USD ($)ft²	Feb. 01, 2016USD ($)ft²	Jan. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 16, 2016ft²	Jun. 24, 2016ft²	May 27, 2016ft²	Apr. 22, 2016USD ($)ft²
Real Estate Properties [Line Items]
Net income (loss)						$ 157,605,000	$ 227,750,000		$ 626,082,000	$ 638,885,000
Proceeds from sales of real estate									122,750,000	389,457,000
Gains on sales of real estate						12,983,000	199,479,000		80,606,000	294,563,000
Impairment loss						1,783,000	0		1,783,000	0
Depreciation and amortization						203,748,000	153,015,000		516,371,000	475,082,000
Revenues						625,228,000	629,884,000		1,914,759,000	1,866,581,000
415 Main Street [Member]
Real Estate Properties [Line Items]
Net income (loss)					$ 1,200,000		(35,000)			6,200,000
Sale Price Of Sold Property				$ 105,400,000
Proceeds from sales of real estate				$ 104,900,000
Net Rentable Area (in sf) | ft²				231,000
Broad Run Business Park [Member]
Real Estate Properties [Line Items]
Sale Price Of Sold Property		$ 18,000,000
Proceeds from sales of real estate		17,900,000
Gains on sales of real estate		$ 13,000,000
601 Massachusetts Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf) | ft²													479,000
804 Carnegie Center [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf) | ft²													130,000
10 CityPoint [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf) | ft²												241,000
888 Boylston Street [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf) | ft²											425,000
Terminated lease at 250 West 55thStreet in NYC [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf) | ft²			85,000
Revenues			$ 45,000,000
Boston Properties Inc | 415 Main Street [Member]
Real Estate Properties [Line Items]
Gains on sales of real estate				$ 60,800,000
Boston Properties Limited Partnership
Real Estate Properties [Line Items]
Net income (loss)						162,771,000	229,748,000		635,219,000	644,880,000
Proceeds from sales of real estate									122,750,000	389,457,000
Gains on sales of real estate						12,983,000	199,723,000		82,775,000	294,807,000
Impairment loss						1,783,000	0		1,783,000	0
Depreciation and amortization						198,582,000	151,017,000		507,234,000	469,087,000
Revenues						625,228,000	$ 629,884,000		$ 1,914,759,000	$ 1,866,581,000
Boston Properties Limited Partnership | 415 Main Street [Member]
Real Estate Properties [Line Items]
Gains on sales of real estate				$ 63,000,000
Consolidated Properties [Member] | 601 Lexington Avenue [Member]
Real Estate Properties [Line Items]
Ownership Percentage by the Company	55.00%
Peterson Way [Member]
Real Estate Properties [Line Items]
Purchase price														$ 78,000,000
Net income (loss)								$ 6,000
Net Rentable Area (in sf) | ft²														218,000
Portion of Building Leased (percentage)														100.00%
Revenues								$ 2,400,000
Future development [Member] | Peterson Way [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf) | ft²														632,000
Land [Member] | Washingtonian North [Member]
Real Estate Properties [Line Items]
Impairment loss						$ 1,800,000
Property Partnerships Member | 601 Lexington Avenue [Member]
Real Estate Properties [Line Items]
Depreciation and amortization	$ 21,400,000
Property Partnerships Member | Boston Properties Inc | 601 Lexington Avenue [Member]
Real Estate Properties [Line Items]
Depreciation and amortization	50,800,000
Property Partnerships Member | Boston Properties Limited Partnership | 601 Lexington Avenue [Member]
Real Estate Properties [Line Items]
Depreciation and amortization	$ 47,600,000
Property Partnerships Member | Office [Member] | 601 Lexington Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf) | ft²	195,000
Property Partnerships Member | Retail Member] | 601 Lexington Avenue [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf) | ft²	25,000

Real Estate Real estate intangi

Real Estate Real estate intangible assets amortization table (Details) - Peterson Way [Member] $ in Thousands	Apr. 22, 2016USD ($)
Acquired-in-Place Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Period from April 22, 2016 through December 31, 2016	$ 578
2,017	867
2,018	867
2,019	867
2,020	867
Acquired Below-Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Period from April 22, 2016 through December 31, 2016	(589)
2,017	(884)
2,018	(884)
2,019	(884)
2,020	$ (884)

Real Estate Real estate activit

Real Estate Real estate activity purchase price allocation (Details) - Peterson Way [Member] $ in Thousands	Apr. 22, 2016USD ($)
Business Acquisition [Line Items]
Land	$ 63,206
Buildings and improvements	7,210
Tenant Improvements	7,669
In-place lease intangibles	4,262
Below-market lease intangible	(4,347)
Net assets acquired	$ 78,000

Investments in Unconsolidated40

Investments in Unconsolidated Joint Ventures (Investments in Unconsolidated Joint Ventures) (Details) $ in Thousands		9 Months Ended
		Sep. 30, 2016USD ($)ft²Land_ParcelsBuildingspayments	Dec. 31, 2015USD ($)
Schedule of Equity Method Investments [Line Items]
Carrying value of the Company's investments in unconsolidated joint ventures		$ 775,659	$ 235,224
Square 407 Limited Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Market Square North
Ownership Percentage		50.00%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ (8,483)	(9,951)
The Metropolitan Square Associates LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Metropolitan Square
Ownership Percentage		51.00%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 9,552	9,179
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%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ (10,898)	(11,958)
WP Project Developer LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Wisconsin Place Land and Infrastructure
Ownership Percentage	[3]	33.30%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 42,073	43,524
Entity Owning Land And Infrastructure Of Project [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		33.30%
Annapolis Junction NFM, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Annapolis Junction
Ownership Percentage	[4]	50.00%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 21,075	29,009
Number of real estate properties | Buildings		4
Parcels of undeveloped land | Land_Parcels		2
540 Madison Venture LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		540 Madison Avenue
Ownership Percentage		60.00%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 69,602	68,983
500 North Capitol LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		500 North Capitol Street, NW
Ownership Percentage		30.00%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ (3,395)	(3,292)
501 K Street LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		1001 6th Street
Ownership Percentage	[5]	50.00%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 42,541	42,584
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%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 33,820	18,508
1265 Main Office JV LLC [Member]
Schedule of Equity Method Investments [Line Items]
Properties		1265 Main Street
Ownership Percentage		50.00%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 23,757	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%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 25,980	11,521
CA-Colorado Center Limited Partnership [Member]
Schedule of Equity Method Investments [Line Items]
Properties		Colorado Center
Ownership Percentage		49.80%
Carrying value of the Company's investments in unconsolidated joint ventures	[1]	$ 507,259
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value of the Company's investments in unconsolidated joint ventures		(22,800)	(25,200)
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value of the Company's investments in unconsolidated joint ventures	[1],[6]	$ 752,883	$ 210,023
[1]	Investments with deficit balances aggregating approximately $22.8 million and $25.2 million at September 30, 2016 and December 31, 2015, respectively, have been reflected within Other Liabilities in 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 for this land parcel, the partner will be entitled to up to two additional payments from the venture based on increases in total entitled square footage of the project above 520,000 square feet and achieving certain project returns at stabilization.
[6]	Investments with deficit balances aggregating approximately $22.8 million and $25.2 million at September 30, 2016 and December 31, 2015, respectively, have been reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

Investments in Unconsolidated41

Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
ASSETS
Real estate and development in process, net		$ 15,789,203	$ 15,555,641
Liabilities and Members'/Partners' Equity [Abstract]
Mortgage notes payable, net		2,077,707	3,435,242
Other Liabilities		461,079	483,601
Total liabilities and equity / capital		18,789,899	18,351,486
Carrying value of the Company's investments in unconsolidated joint ventures		775,659	235,224
Unconsolidated Joint Ventures [Member]
ASSETS
Real estate and development in process, net		1,460,808	1,072,412
Other assets		294,912	252,285
Total assets		1,755,720	1,324,697
Liabilities and Members'/Partners' Equity [Abstract]
Mortgage notes payable, net		826,807	830,125
Other Liabilities		54,390	44,549
Members'/Partners' equity		874,523	450,023
Total liabilities and equity / capital		1,755,720	1,324,697
Company's share of equity		449,351	237,070
Basis differentials	[1]	303,532	(27,047)
Carrying value of the Company's investments in unconsolidated joint ventures	[2],[3]	752,883	210,023
Unconsolidated Joint Ventures [Member]
Liabilities and Members'/Partners' Equity [Abstract]
Carrying value of the Company's investments in unconsolidated joint ventures		(22,800)	$ (25,200)
Colorado Center [Member]
Liabilities and Members'/Partners' Equity [Abstract]
Basis differentials		$ 330,100
[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 result from impairments of investments, acquisitions through joint ventures with no change in control 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. At September 30, 2016, there is an aggregate basis differential of approximately $330.1 million between the carrying value of the Company’s investment in the joint venture that owns Colorado Center and the joint venture’s basis in the assets and liabilities, which differential (excluding land) shall be amortized over the remaining lives of the related assets and liabilities.
[2]	Investments with deficit balances aggregating approximately $22.8 million and $25.2 million at September 30, 2016 and December 31, 2015, respectively, have been reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.
[3]	Investments with deficit balances aggregating approximately $22.8 million and $25.2 million at September 30, 2016 and December 31, 2015, respectively, have been reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

Investments in Unconsolidated42

Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015		Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Total revenue		$ 625,228		$ 629,884	$ 1,914,759		$ 1,866,581
Expenses
Depreciation and amortization		203,748		153,015	516,371		475,082
Total expenses		467,623		402,134	1,288,677		1,227,696
Operating income		157,605		227,750	626,082		638,885
Other expense
Interest expense		104,641		108,727	314,953		326,018
Losses on Extinguishment of Debt		371		0	371		0
Net income		71,504		323,271	405,083		633,180
Income from unconsolidated joint ventures		1,464		2,647	5,489		20,559
Distribution related to excess loan proceeds					0		24,527
Mortgage notes payable, net		2,077,707			2,077,707				$ 3,435,242
Unconsolidated Joint Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Total revenue	[1]	49,002		38,197	125,039		116,881
Expenses
Operating		21,753		15,896	54,779		47,995
Depreciation and amortization		12,038		8,832	30,306		26,854
Total expenses		33,791		24,728	85,085		74,849
Operating income		15,211		13,469	39,954		42,032
Other expense
Interest expense		8,400		8,019	25,172		23,985
Net income		6,811		5,450	14,782		18,047
Company's share of net income		3,179		2,481	6,830		20,025	[2]
Basis differential		(1,715)	[3]	166	(1,341)	[3]	534
Income from unconsolidated joint ventures		1,464		2,647	5,489		20,559
Straight-line rent adjustments		5,200		(300)	11,000		1,700
Mortgage notes payable, net		826,807			826,807				$ 830,125
Colorado Center [Member]
Other expense
Straight-line rent adjustments		700			700	[3]
"Above" and "below" market rent adjustments, net		$ 500			$ 500	[3]
BP/CRF 901 New York Avenue LLC [Member]
Other expense
Distribution related to excess loan proceeds							24,500
Mortgage notes payable, net				$ 225,000			$ 225,000
[1]	Includes straight-line rent adjustments of approximately $5.2 million and $(0.3) million for the three months ended September 30, 2016 and 2015, respectively, and approximately $11.0 million and $1.7 million for the nine months ended September 30, 2016 and 2015, respectively.
[2]	During the nine months ended September 30, 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 nine months ended September 30, 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.
[3]	Includes a straight-line rent adjustment of approximately $0.7 million and a net above-/below-market rent adjustment of approximately $0.5 million for the three and nine months ended September 30, 2016.

Investments in Unconsolidated43

Investments in Unconsolidated Joint Ventures Investments in Unconsolidated Joint Ventures (Narrative) (Details) $ in Thousands	Jul. 01, 2016USD ($)ft²aVehiclesBuildings	Apr. 11, 2016USD ($)ft²yr	Apr. 04, 2016USD ($)ft²yr	Sep. 30, 2016USD ($)	Dec. 31, 2015USD ($)
Schedule of Equity Method Investments [Line Items]
Secured Debt				$ 2,077,707	$ 3,435,242
Construction Loans [Member] | Annapolis Junction Building Seven [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage			50.00%
Construction Loan			$ 21,500
Construction Loan Facility Borrowing Capacity			$ 22,000
Debt Instrument, Basis Spread on Variable Rate			1.65%
Number of extensions			1
Extension Option (in years) | yr			1
Net Rentable Area (in sf) | ft²			127,000
Secured Debt [Member] | Annapolis Junction Buidling One [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%
Secured Debt		$ 39,700
Debt Instrument, Basis Spread on Variable Rate		1.75%
Number of extensions		1
Extension Option (in years) | yr		3
Net Rentable Area (in sf) | ft²		118,000
Colorado Center [Member] | Colorado Center [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	49.80%
Net Rentable Area (in sf) | ft²	1,184,000
Aggregate purchase price	$ 511,100
Purchase price, net	$ 503,600
Number of buildings | Buildings	6
Land acquired (in acres) | a	15
Vehicles In Structured Parking | Vehicles	3,100

Investments in Unconsolidated44

Investments in Unconsolidated Joint Ventures Business acquisition purchase price table (Details) - Colorado Center [Member] - Colorado Center [Member] $ in Thousands	Jul. 01, 2016USD ($)
Schedule of Equity Method Investments [Line Items]
Land	$ 189,597
Site Improvements	9,050
Buildings and improvements	259,592
Tenant Improvements	17,234
In-place lease intangibles	43,157
Above-market lease, acquired	819
Below-market lease, acquired	(16,461)
Net assets acquired	$ 502,988

Mortgage Notes Payable (Details

Mortgage Notes Payable (Details) - USD ($) $ in Thousands	Sep. 01, 2016	Apr. 11, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Repayments of Secured Debt					$ 1,323,284	$ 20,137
Gains (Losses) on Extinguishment of Debt			$ (371)	$ 0	$ (371)	$ 0
Fountain Square [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of Secured Debt		$ 211,300
Coupon/Stated Rate		5.71%
599 Lexington Avenue [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of Secured Debt	$ 750,000
Coupon/Stated Rate	5.57%
Effective Rate	5.41%
Gains (Losses) on Extinguishment of Debt	$ 400
Embarcadero Center Four [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of Secured Debt	$ 344,800
Coupon/Stated Rate	6.10%
Effective Rate	7.02%
Gains (Losses) on Extinguishment of Debt	$ (700)

Unsecured Senior Notes Schedule

Unsecured Senior Notes Schedule of Unsecured Senior Notes (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2016		Aug. 17, 2016	Jan. 20, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total		$ 7,243,767				$ 5,264,819
Boston Properties Limited Partnership
Debt Instrument [Line Items]
Total		7,243,767				$ 5,264,819
Boston Properties Limited Partnership | Senior Notes [Member]
Debt Instrument [Line Items]
Principal Amount		7,300,000
Net unamortized discount		(19,429)
Deferred Finance Costs, Net		(36,804)
Total		$ 7,243,767
Boston Properties Limited Partnership | 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 | 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 | 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 | 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 | 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 | 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 | 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
Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Notes 3.766%
Debt Instrument [Line Items]
Coupon/Stated Rate		3.65%			3.65%
Effective Rate		3.766%	[1]		3.766%
Principal Amount		$ 1,000,000			$ 1,000,000
Maturity Date	[2]	Feb. 1, 2026
Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Notes 3.495%
Debt Instrument [Line Items]
Coupon/Stated Rate		2.75%		2.75%
Effective Rate		3.495%	[1]	3.495%
Principal Amount		$ 1,000,000		$ 1,000,000
Maturity Date	[2]	Oct. 1, 2026
[1]	Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.
[2]	No principal amounts are due prior to maturity.

Unsecured Senior Notes Unsecu47

Unsecured Senior Notes Unsecured Senior Notes (Narrative) (Details) - USD ($) $ in Thousands	Aug. 17, 2016	Jan. 20, 2016	Sep. 30, 2016		Sep. 30, 2015
Debt Instrument [Line Items]
Proceeds from Issuance of Unsecured Debt			$ 1,989,790		$ 0
Boston Properties Limited Partnership
Debt Instrument [Line Items]
Proceeds from Issuance of Unsecured Debt			$ 1,989,790		$ 0
Boston Properties Limited Partnership | 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%
Principal Amount			$ 7,300,000
Unsecured Senior Notes 3.766% | Boston Properties Limited Partnership | Senior Notes [Member]
Debt Instrument [Line Items]
Principal Amount		$ 1,000,000	$ 1,000,000
Coupon/Stated Rate		3.65%	3.65%
Senior Notes Pricing		99.708%
Effective Rate		3.766%	3.766%	[1]
Proceeds from Issuance of Unsecured Debt		$ 988,900
Unsecured Senior Notes 3.495% | Boston Properties Limited Partnership | Senior Notes [Member]
Debt Instrument [Line Items]
Principal Amount	$ 1,000,000		$ 1,000,000
Coupon/Stated Rate	2.75%		2.75%
Senior Notes Pricing	99.271%
Effective Rate	3.495%		3.495%	[1]
Proceeds from Issuance of Unsecured Debt	$ 984,700
[1]	Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.

Derivative Instruments and He48

Derivative Instruments and Hedging Activities (Details) $ in Thousands	Aug. 17, 2016USD ($)swapsyr	Jan. 06, 2016USD ($)swapsyr	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)swapsyr	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax			$ 5,712	$ (30,156)	$ (85,285)	$ (18,050)
Cash payment to settle interest rate swap contracts					(114,321)	(73,370)
Losses from interest rate contracts			$ (140)	0	$ (140)	0
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax							$ (10,302)
Notional Amount							950,000
Boston Properties Limited Partnership | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax							(4,231)
Number of interest rate swap agreements entered into (swap contracts) | swaps	17
Term of anticipated mortgage loan (in years) | yr	10
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) | yr	10
Average Fixed Interest Rate	2.423%
Notional Amount	$ 550,000						550,000
767 Fifth Partners LLC [Member]
Debt Instrument [Line Items]
Ownership Percentage by the Company			60.00%		60.00%
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax							(6,071)
Number of interest rate swap agreements entered into (swap contracts) | swaps		2			16
Term of anticipated mortgage loan (in years) | yr					10
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) | yr		10			10
Derivative, Net Liability Position, Aggregate Fair Value			$ 46,500		$ 46,500
Assets Needed for Immediate Settlement, Aggregate Fair Value			$ 46,500		46,500
Amount of loss related to the effective portion recognized in accumulated other comprehensive loss					$ 46,400
Average Fixed Interest Rate			2.619%		2.619%
Notional Amount		$ 50,000	$ 450,000		$ 450,000		$ 400,000
Estimated current balance held in Accumulated Other Comprehensive Loss to be reclassified into earnings within the next twelve months					(1,500)
Boston Properties Limited Partnership
Debt Instrument [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax			5,712	(30,156)	(85,285)	(18,050)
Cash payment to settle interest rate swap contracts					(114,321)	(73,370)
Losses from interest rate contracts			$ (140)	$ 0	$ (140)	$ 0
Boston Properties Limited Partnership | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Cash payment to settle interest rate swap contracts	49,300
Losses from interest rate contracts	(100)
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion	49,200
Derivative Instruments Loss Reclassified From Accumulated OCI Into Income Effective yearly amount	$ 4,900
Boston Properties Limited Partnership | Unsecured Senior Notes 3.495% | Senior Notes [Member]
Debt Instrument [Line Items]
Coupon/Stated Rate	2.75%		2.75%		2.75%

Derivative Instruments and He49

Derivative Instruments and Hedging Activities Derivative Instrument and Hedging Activities Notional Table (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Aug. 17, 2016	Jan. 06, 2016
Derivative [Line Items]
Fair Value	$ 5,712	$ (30,156)	$ (85,285)	$ (18,050)
Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount					$ 950,000
Fair Value					(10,302)
Boston Properties Limited Partnership | Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount					550,000	$ 550,000
Fair Value					(4,231)
Boston Properties Limited Partnership | Interest Rate Swap [Member] | Interest Rate Swap Range 2.348% - 2.571% [Member]
Derivative [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 | Interest Rate Swap [Member] | Interest Rate Swap Range 2.129% - 2.325% [Member]
Derivative [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 [Line Items]
Notional Amount	450,000		450,000		400,000		$ 50,000
Fair Value					(6,071)
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] | Interest Rate Swap Range 2.336% - 2.950% [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	$ 450,000		$ 450,000
Derivative, Lower Fixed Interest Rate Range	2.336%		2.336%
Derivative, Higher Fixed Interest Rate Range	2.95%		2.95%
Fair Value			$ (46,405)
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] | Interest Rate Swap Range 2.677% - 2.950% [Member]
Derivative [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 [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 Instruments and He50

Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities Gain or Loss Recognized Related to Cash Flow hedges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative [Line Items]
Amount of gain (loss) related to the effective portion recognized in other comprehensive loss	$ 5,712	$ (30,156)	$ (85,285)	$ (18,050)
Amount of loss related to the effective portion subsequently reclassified to earnings	(1,190)	(627)	(2,445)	(1,882)
Amount of loss related to the ineffective portion and amount excluded from effectiveness testing	$ (140)	$ 0	$ (140)	$ 0

Derivative Instruments and He51

Derivative Instruments and Hedging Activities Derivative Instruments and Hedging Activities Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Accumulated Other Comprehensive Income or Loss [Roll Forward]
Beginning Balance				$ (14,114)	$ (9,304)	$ (9,304)
Effective portion of interest rate contracts		$ 5,712	$ (30,156)	(85,285)	(18,050)
Amortization of interest rate contracts	[1]	1,190	627	2,445	1,882
Other comprehensive loss attributable to noncontrolling interests		(1,097)	7,056	23,011	4,847
Ending Balance		(73,943)	(20,625)	(73,943)	(20,625)	(14,114)
Boston Properties Limited Partnership
Accumulated Other Comprehensive Income or Loss [Roll Forward]
Beginning Balance				(18,337)	(12,973)	(12,973)
Effective portion of interest rate contracts		5,712	(30,156)	(85,285)	(18,050)
Amortization of interest rate contracts	[2]	1,190	627	2,445	1,882
Other comprehensive loss attributable to noncontrolling interests				16,134	3,540
Ending Balance		$ (85,043)	$ (25,601)	$ (85,043)	$ (25,601)	$ (18,337)
[1]	Amounts reclassified from comprehensive income primarily to interest expense within the Boston Properties, Inc.’s Consolidated Statements of Operations.
[2]	Amounts reclassified from comprehensive income primarily to interest expense within the Boston Properties Limited Partnership's Consolidated Statements of Operations.

Commitments And Contingencies (

Commitments And Contingencies (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2009	Jul. 05, 2016	Sep. 09, 2015	Mar. 11, 2015	Dec. 31, 2014	Jan. 10, 2014
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations	$ 14
Property insurance program per occurrence limits	1,000
Per occurrence limit for NBCR Coverage	1,000
Value of program trigger	$ 120
Coinsurance of program trigger	16.00%
Deductible in insurance as a percentage of the value of the affected property, San Francisco and Los Angeles	3.00%
Per occurrence limit of the earthquake insurance which covers San Francisco and Los Angeles regions	$ 170
Annual aggregate limit of the earthquake insurance which covers San Francisco and Los Angeles regions	170
Amount of earthquake insurance provided by IXP, LLC as direct insurer San Francisco and Los Angeles	20
Earthquake Coverage Included In Builders Risk Policy For Salesforce Tower	60
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation	$ 14.5
Ownership Percentage by the Company	60.00%
Property insurance program per occurrence limits	$ 1,625
Lehman [Member]
Commitments And Contingencies [Line Items]
Bankruptcy claim, amount filed by general creditor		$ 45.3
Bankruptcy claim amount allowed by court to creditor							$ 45.2
Bankruptcy Claims, Amount of Claims Settled			$ 1.4	$ 3.6	$ 4.5	$ 7.7
Bankruptcy remaining claim amount allowed by court to creditor	28
601 Lexington Avenue [Member]
Commitments And Contingencies [Line Items]
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP	250
Boston Properties Limited Partnership
Commitments And Contingencies [Line Items]
Operating partnership guarantee to cover liabilities of IXP	$ 20

Noncontrolling Interests (Narra

Noncontrolling Interests (Narrative) (Details) - Boston Properties Limited Partnership	Sep. 30, 2016shares
Noncontrolling Interests [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Operating Partnership (OP) Units (in shares)	17,096,675
Long-Term Incentive Plan (LTIP) Units (in shares)	905,494
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	166,629
2013 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2013 MYLTIP (in units)	93,928
MYLTIP 2014 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2014 MYLTIP (in units)	474,415
2015 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2015 MYLTIPS (in units)	367,218
2016 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2016 MYLTIPs (in units)	473,360

Noncontrolling Interests (Redee

Noncontrolling Interests (Redeemable Preferred Units) (Narrative) (Details) - Series Four Preferred Units [Member] - Noncontrolling Interests [Member] $ / shares in Units, $ in Millions	Jun. 25, 2015USD ($)$ / sharesshares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Preferred Units Liquidation Preference | $ / shares	$ 50
Series Four Preferred Units Redeemed (in shares) | shares	12,667
Redemption of Series Four Preferred Units | $	$ 0.6
Series Four Preferred Units Annual Dividend Payable Rate	2.00%

Noncontrolling Interests (Red55

Noncontrolling Interests (Redeemable Preferred Units) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Activity of Noncontrolling Interests [Roll Forward]
Net Income	$ 0	$ 0	$ 0	$ (6)
Redeemable Preferred Units [Member]
Activity of Noncontrolling Interests [Roll Forward]
Beginning Balance				633
Net Income				6
Distributions				(6)
Redemption of redeemable preferred units (Series Four Preferred Units)				(633)
Ending Balance		$ 0		$ 0

Noncontrolling Interests Redeem

Noncontrolling Interests Redeemable interest in property partnership (Narrative) (Details) - USD ($) $ in Thousands	Sep. 15, 2015	Aug. 06, 2015	Oct. 04, 2012	Sep. 30, 2016	Sep. 30, 2015
Noncontrolling Interest [Line Items]
Payments for Repurchase of Redeemable Noncontrolling Interest				$ 0	$ 108,499
Fountain Square [Member]
Noncontrolling Interest [Line Items]
Aggregate purchase price			$ 385,000
Indebtedness assumed			$ 211,300
Ownership Percentage	50.00%	50.00%	50.00%
Fixed Price to Acquire Remaining Portion of Joint venture		$ 100,900
Payments to Acquire Businesses, Gross			$ 87,000
Ownership Percentage by the Company			50.00%
Future Fixed Price to Acquire Remaining Portion of Joint venture			$ 102,000
Fixed Price Option Expiration Date			Jan. 31, 2016
Payments for Repurchase of Redeemable Noncontrolling Interest	$ 100,900
Mortgage debt assumed upon acquisition of noncontrolling interest	$ 105,600

Noncontrolling Interests Noncon

Noncontrolling Interests Noncontrolling Redeemable Property Partnerships (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Noncontrolling Interest Redeemable Property Partnership [Abstract]
Beginning Balance		$ 104,692
Net loss		(7)
Distributions		(2,900)
Adjustment to Reflect Redeemable Interest at Redemption Value		5,128
Acquisition of interest	$ (106,913)
Ending Balance		$ 0

(Common Units) (Narrative) (Det

(Common Units) (Narrative) (Details) $ / shares in Units, $ in Millions	Feb. 04, 2016USD ($)shares	Feb. 06, 2015USD ($)shares	Sep. 30, 2016USD ($)yr$ / sharesshares	May 02, 2016shares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Conversion of LTIP Units to OP Units (in units)				625,043
2012 OPP Units and 2013 MYLTIP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Conversion of LTIP Units to OP Units (in units)				32,349
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares)			173,694
Redemption of OP units issued on conversion of LTIP Units (in shares)			86,684
Restriction on redemption of OP Unit to Common Stock (in years) | yr			1
Redemption of OP Unit equivalence to Common Stock (in shares)			1
Common units of operating partnership if converted value | $			$ 2,500
Closing price of common stock (in dollars per share) | $ / shares			$ 136.29
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		174,549
2013 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target	109.50%
Value of MYLTIP Awards | $	$ 13.5
2013 MYLTIP Units Forfeited	205,762
Boston Properties Limited Partnership | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance Awards LTIP Units distribution as percentage of OP Unit distribution prior to measurement date			10.00%
Boston Properties Limited Partnership | MYLTIP 2014 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2014 MYLTIP (in units)			474,415
Boston Properties Limited Partnership | 2015 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2015 MYLTIPS (in units)			367,218
Boston Properties Limited Partnership | 2016 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2016 MYLTIPs (in units)			473,360

Noncontrolling Interests Common

Noncontrolling Interests Common units distributions (Details) - $ / shares	Jul. 29, 2016	Apr. 29, 2016	Jan. 28, 2016		Sep. 01, 2016
special dividend [Member]
Dividends Payable [Line Items]
Distributions made to OP and LTIP units per unit (in dollars per unit)			$ 1.25
Boston Properties Limited Partnership
Dividends Payable [Line Items]
Distributions Declared To OP And LTIP Units Per Unit					$ 0.65
Distributions Declared To MYLTIP Units Per Unit (in dollars per unit)					$ 0.065
Distributions made to OP and LTIP units per unit (in dollars per unit)	$ 0.65	$ 0.65	1.90	[1]
Distribution paid to outperformance awards, MYLTIP Units (in dollars per unit)	$ 0.065	$ 0.065	$ 0.065
[1]	Includes a special distribution of $1.25 per unit.

Noncontrolling Interests Comm60

Noncontrolling Interests Common units for Boston Properties LImited Partnership (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Noncontrolling Interest [Line Items]
Conversion of redeemable partnership units		$ 0
Accumulated Other Comprehensive Income (Loss)	$ (73,943)	(20,625)	$ (14,114)	$ (9,304)
Noncontrolling Interests [Member]
Noncontrolling Interest [Line Items]
Conversion of redeemable partnership units	(10,094)	(12,577)
Boston Properties Limited Partnership
Noncontrolling Interest [Line Items]
Accumulated Other Comprehensive Income (Loss)	(85,043)	(25,601)	$ (18,337)	$ (12,973)
Boston Properties Limited Partnership | Noncontrolling Interests [Member]
Noncontrolling Interest [Line Items]
Beginning balance	2,286,689	2,310,046
Contributions	31,492	39,036
Net Income	42,120	50,906
Distributions	(35,500)	(35,307)
Conversion of redeemable partnership units	(5,881)	(14,157)
Unearned Compensation	(10,072)	(9,729)
Accumulated Other Comprehensive Income (Loss)	(6,877)	(1,307)
Adjustments To Reflect Redeemable Preferred Units At Redemption Value	151,545	(216,037)
Ending balance	$ 2,453,516	$ 2,123,451

Noncontrolling Interests (Prope

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) $ in Thousands	May 12, 2016	Sep. 18, 2015USD ($)ft²	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Noncontrolling Interest [Line Items]
Proceeds from sales of real estate					$ 122,750	$ 389,457
Property partnerships			$ 1,525,042		1,525,042		$ 1,574,400
Gains on sales of real estate			12,983	$ 199,479	80,606	294,563
505 9th Street [Member] | Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Proceeds from sales of real estate		$ 194,600
Ownership Percentage by the Company		50.00%
Sale Price Of Sold Property		$ 318,000
Mortgage notes payable assigned in connection with the sale of real estate		$ 117,000
Net Rentable Area (in sf) | ft²		322,000
Gains on sales of real estate		$ 199,500
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
Boston Properties Limited Partnership
Noncontrolling Interest [Line Items]
Proceeds from sales of real estate					122,750	389,457
Gains on sales of real estate			12,983	$ 199,723	82,775	$ 294,807
Boston Properties Limited Partnership | 505 9th Street [Member] | Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Gains on sales of real estate		$ 199,700
Salesforece Tower[Member] | Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Ownership Percentage	5.00%
Portion of project costs covered by a construction loan	50.00%
Portion of costs funded (in percentage)	50.00%
Debt Instrument, Basis Spread on Variable Rate	3.00%
Salesforece Tower[Member] | Boston Properties, Inc [Member] | Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Costs funded (in percentage)	2.50%
Preferred equity funded			$ 2,000		$ 2,000

Noncontrolling Interests Proper

Noncontrolling Interests Property Partnerships (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Activity of Noncontrolling Interests [Roll Forward]
Beginning Balance			$ 1,574,400
Capital contributions			(6,737)	$ (1,758)
Net income	$ (17,225)	$ 115,240	53	139,712
Accumulated other comprehensive loss	(1,097)	7,056	23,011	4,847
Ending Balance	1,525,042		1,525,042
Property Partnerships Member
Activity of Noncontrolling Interests [Roll Forward]
Beginning Balance			1,574,400	1,602,467
Capital contributions			5,417	1,758
Net income			53	134,591
Accumulated other comprehensive loss			(16,134)	(3,540)
Distributions			(38,694)	(144,468)
Ending Balance	$ 1,525,042	$ 1,590,808	$ 1,525,042	$ 1,590,808

Stockholders' Equity _ Partne63

Stockholders' Equity / Partners' Capital Narrative (Details)	Jun. 03, 2014USD ($)yr	Sep. 30, 2016USD ($)$ / sharesshares	Mar. 27, 2018$ / shares	Dec. 31, 2015USD ($)$ / sharesshares
Class of Stock [Line Items]
Common stock, shares outstanding		153,773,012		153,579,966
General Partners' Capital Account, Units Outstanding		1,717,752
Limited Partners' Capital Account, Units Outstanding		152,055,260
Shares of Common Stock in connection with the redemption of an equal number of OP Units (in shares)		173,694
Common Stock, Value, Issued | $		$ 1,538,000		$ 1,536,000
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 Sale In Years | yr	3
Common Stock, Value, Issued | $		$ 0
Series B Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding (in shares)		80,000		80,000
Series B, Dividend Rate, Percentage		5.25%
Series B, Liquidation Preference Per Share (dollars per share) | $ / shares		$ 2,500		$ 2,500
Ratio of depository shares to shares of Series B Preferred Stock		0.01
Depository shares of Series B Cumulative Redeemable Preferred [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding (in shares)		8,000,000
Series B, Liquidation Preference Per Share (dollars per share) | $ / shares		$ 25
Subsequent Event [Member] | Series B Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Series B, Liquidation Preference Per Share (dollars per share) | $ / shares			$ 2,500
Subsequent Event [Member] | Depository shares of Series B Cumulative Redeemable Preferred [Member]
Class of Stock [Line Items]
Series B, Liquidation Preference Per Share (dollars per share) | $ / shares			$ 25
Boston Properties Limited Partnership
Class of Stock [Line Items]
General Partners' Capital Account, Units Outstanding		1,717,752		1,715,092
Limited Partners' Capital Account, Units Outstanding		152,055,260		151,864,874
Boston Properties Limited Partnership | Series B Cumulative Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding (in shares)		80,000		80,000
Series B, Liquidation Preference Per Share (dollars per share) | $ / shares		$ 2,500		$ 2,500

Stockholders' Equity _ Partne64

Stockholders' Equity / Partners' Capital Stockholders' Equity / Partners' Capital Dividends / Distributions (Details) - $ / shares	Aug. 15, 2016	Jul. 29, 2016	May 16, 2016	Apr. 29, 2016	Feb. 16, 2016	Jan. 28, 2016		Sep. 01, 2016
Entity Information [Line Items]
Dividends Payable, Amount Per Share / Unit								$ 0.65
Dividends, Per Share / Unit		$ 0.65		$ 0.65		$ 1.90	[1]
Special dividend / distribution (per share / common unit amount)						1.25
Boston Properties Limited Partnership
Entity Information [Line Items]
Dividends Payable, Amount Per Share / Unit								0.65
Dividends, Per Share / Unit		$ 0.65		$ 0.65		1.90	[1]
Special dividend / distribution (per share / common unit amount)						$ 1.25
Series B Cumulative Redeemable Preferred Stock [Member]
Entity Information [Line Items]
Dividends Payable, Amount Per Share / Unit								$ 32.8125
Dividends, Per Share / Unit	$ 32.8125		$ 32.8125		$ 32.8125
[1]	Includes a special dividend/distribution of $1.25 per share/OP Unit and LTIP Unit.

Earnings Per Share _ Common U65

Earnings Per Share / Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Basic Earnings:
Net income attributable to the Company's common shareholders / unitholders	$ 76,753	$ 184,082	$ 355,114	$ 434,702
Net income attributable to the Company's common shareholders / unitholders (in shares / units)	153,754,000	153,595,000	153,681,000	153,426,000
Net income (in dollars per share / unit)	$ 0.50	$ 1.20	$ 2.31	$ 2.83
Allocation of undistributed earnings to participating securities (numerator)		$ (221)	$ (189)	$ (361)
Allocation of undistributed earnings to participating securities (in shares / units)		0	0	0
Allocation of undistributed earnings to participating securities (in dollars per shares / units)		$ 0	$ 0	$ 0
Net income attributable to the Company's common shareholders / unitholders		$ 183,861	$ 354,925	$ 434,341
Net income attributable to the Company's common shareholders / unitholders (in shares / units)		153,595,000	153,681,000	153,426,000
Net income attributable to the Company's common shareholders / unitholders (in dollars per share / unit)		$ 1.20	$ 2.31	$ 2.83
Effect of Dilutive Securities:
Stock Based Compensation, Income (Numerator)	$ 0	$ 0	$ 0	$ 0
Stock Based Compensation, Shares / Units (Denominator)	382,000	191,000	290,000	399,000
Stock Based Compensation, Per Share / Unit Amount (in dollars per share / unit)	$ 0	$ 0	$ 0	$ (0.01)
Diluted Earnings:
Net income attributable to the Company's common shareholders / unitholders (Numerator)	$ 76,753	$ 183,861	$ 354,925	$ 434,341
Net income attributable to the Company's common shareholders / unitholders (in shares / units) (Denominator)	154,136,000	153,786,000	153,971,000	153,825,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.50	$ 1.20	$ 2.31	$ 2.82
Boston Properties Limited Partnership
Entity Information [Line Items]
Redeemable Common Units	17,625,000	17,565,000	17,672,000	17,705,000
Basic Earnings:
Net income attributable to the Company's common shareholders / unitholders	$ 91,306	$ 207,626	$ 408,540	$ 491,847
Net income attributable to the Company's common shareholders / unitholders (in shares / units)	171,379,000	171,160,000	171,353,000	171,131,000
Net income (in dollars per share / unit)	$ 0.53	$ 1.21	$ 2.38	$ 2.87
Allocation of undistributed earnings to participating securities (numerator)		$ (246)	$ (210)	$ (402)
Allocation of undistributed earnings to participating securities (in shares / units)		0	0	0
Allocation of undistributed earnings to participating securities (in dollars per shares / units)		$ 0	$ 0	$ 0
Net income attributable to the Company's common shareholders / unitholders		$ 207,380	$ 408,330	$ 491,445
Net income attributable to the Company's common shareholders / unitholders (in shares / units)		171,160,000	171,353,000	171,131,000
Net income attributable to the Company's common shareholders / unitholders (in dollars per share / unit)		$ 1.21	$ 2.38	$ 2.87
Effect of Dilutive Securities:
Stock Based Compensation, Income (Numerator)	$ 0	$ 0	$ 0	$ 0
Stock Based Compensation, Shares / Units (Denominator)	382,000	191,000	290,000	399,000
Stock Based Compensation, Per Share / Unit Amount (in dollars per share / unit)	$ 0	$ 0	$ 0	$ 0
Diluted Earnings:
Net income attributable to the Company's common shareholders / unitholders (Numerator)	$ 91,306	$ 207,380	$ 408,330	$ 491,445
Net income attributable to the Company's common shareholders / unitholders (in shares / units) (Denominator)	171,761,000	171,351,000	171,643,000	171,530,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.53	$ 1.21	$ 2.38	$ 2.87

Stock Option and Incentive Pl66

Stock Option and Incentive Plan Stock Option and Incentive Plan (Narrative) (Details)	Feb. 04, 2016USD ($)shares	Jan. 25, 2016USD ($)yrtiersindices	Feb. 06, 2015USD ($)shares
2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
TSR Measurement, Years | yr		3
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
OPP Units 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned			$ 40,000,000
2012 OPP Units Forfeited | shares			174,549
Outperformance awards earned			$ 32,100,000
Potential maximum amount of Outperformance Awards earned (percent)			80.00%
2013 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards	$ 13,500,000
Final awards percentage of target	109.50%
2013 MYLTIP Units Forfeited | shares	205,762
Cohen & Steers Realty Majors Portfolio Index [Member] | 2016 MYLTIP [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] | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Percentage of Index Used to Compare to TSR		50.00%
Threshold [Member] | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier		$ 9,900,000
Target [Member] | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier		19,700,000
High [Member] | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of Each Tier		49,300,000
Maximum [Member] | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned		49,300,000
Minimum [Member] | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Potential Awards Earned		$ 0
MYLTIP vesting 2019 [Member] | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage		50.00%
MYLTIP vesting 2020 [Member] | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Percentage		50.00%

Stock Option and Incentive Pl67

Stock Option and Incentive Plan (Restricted Stock) (Narrative) (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)$ / sharesshares	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)VestingInstallments$ / sharesshares	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued | shares	153,851,912		153,851,912		153,658,866
Stock based Compensation Expense	$ 7,100	$ 5,900	$ 23,600	$ 21,000
Common Stock, Value, Issued	$ 1,538		$ 1,538		$ 1,536
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued | shares	22,067		22,067
Employee and director payment per share (in dollars per share) | $ / shares			$ 0.01
Common Stock, Value, Issued	$ 2,500		$ 2,500
Employee's weighted average cost per share (in dollars per share) | $ / shares	$ 113.51		$ 113.51
LTIPs (including 2012 OPP and 2013 MYLTIPS) And Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting annual installments | VestingInstallments			4
Unrecognized compensation expenses	$ 22,800		$ 22,800
Unvested MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses	$ 22,900		$ 22,900
Weighted-average period (years)	2 years 6 months
Boston Properties Limited Partnership | LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares) | shares	147,872		147,872
Value of LTIP units issued			$ 15,400
Per unit fair value weighted-average (in dollars per share) | $ / shares	$ 103.83		$ 103.83
Expected life assumed to calculate per unit fair value per LTIP unit (years)			5 years 8 months 12 days
Risk-free rate			1.61%
Expected price volatility			33.00%
Boston Properties Limited Partnership | 2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued (in shares) | shares	475,004		475,004
Boston Properties Limited Partnership | LTIPs and 2016 MYLTIP Units [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

Segment Information (Schedule O

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Rental Revenue: Office	$ 602,138	$ 607,242	$ 1,849,745	$ 1,800,596
Rental Revenue: Residential	4,372	4,111	12,509	14,776
Rental Revenue: Hotel	12,354	12,619	33,919	35,107
Total revenue	$ 618,864	$ 623,972	$ 1,896,173	$ 1,850,479
Rental Revenue: % of Grand Totals	100.00%	100.00%	100.00%	100.00%
Rental Expenses: Office	$ 226,337	$ 218,262	$ 660,241	$ 648,999
Rental Expenses: Residential	2,223	1,534	5,429	6,611
Rental Expenses: Hotel	8,118	8,125	23,730	24,196
Rental Expenses: Total	$ 236,678	$ 227,921	$ 689,400	$ 679,806
Rental Expenses: % Of Grand Totals	100.00%	100.00%	100.00%	100.00%
Net operating Income	$ 382,186	$ 396,051	$ 1,206,773	$ 1,170,673
Net operating Income: % of Grand Totals	100.00%	100.00%	100.00%	100.00%
Boston [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Office	$ 183,975	$ 179,278	$ 540,850	$ 536,241
Rental Revenue: Residential	1,227	1,275	3,578	3,584
Rental Revenue: Hotel	12,354	12,619	33,919	35,107
Total revenue	$ 197,556	$ 193,172	$ 578,347	$ 574,932
Rental Revenue: % of Grand Totals	31.92%	30.96%	30.50%	31.07%
Rental Expenses: Office	$ 71,254	$ 71,898	$ 210,695	$ 218,002
Rental Expenses: Residential	1,141	485	2,174	1,505
Rental Expenses: Hotel	8,118	8,125	23,730	24,196
Rental Expenses: Total	$ 80,513	$ 80,508	$ 236,599	$ 243,703
Rental Expenses: % Of Grand Totals	34.02%	35.32%	34.32%	35.85%
Net operating Income	$ 117,043	$ 112,664	$ 341,748	$ 331,229
Net operating Income: % of Grand Totals	30.62%	28.45%	28.32%	28.29%
New York [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Office	$ 237,262	$ 253,612	$ 773,077	$ 753,142
Rental Revenue: Residential	0	0	0	0
Rental Revenue: Hotel	0	0	0	0
Total revenue	$ 237,262	$ 253,612	$ 773,077	$ 753,142
Rental Revenue: % of Grand Totals	38.34%	40.64%	40.77%	40.70%
Rental Expenses: Office	$ 95,073	$ 88,496	$ 272,620	$ 259,218
Rental Expenses: Residential	0	0	0	0
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	$ 95,073	$ 88,496	$ 272,620	$ 259,218
Rental Expenses: % Of Grand Totals	40.17%	38.83%	39.54%	38.13%
Net operating Income	$ 142,189	$ 165,116	$ 500,457	$ 493,924
Net operating Income: % of Grand Totals	37.21%	41.69%	41.47%	42.19%
San Francisco [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Office	$ 80,235	$ 77,315	$ 235,076	$ 223,561
Rental Revenue: Residential	0	0	0	0
Rental Revenue: Hotel	0	0	0	0
Total revenue	$ 80,235	$ 77,315	$ 235,076	$ 223,561
Rental Revenue: % of Grand Totals	12.96%	12.39%	12.40%	12.08%
Rental Expenses: Office	$ 26,037	$ 25,883	$ 75,412	$ 73,119
Rental Expenses: Residential	0	0	0	0
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	$ 26,037	$ 25,883	$ 75,412	$ 73,119
Rental Expenses: % Of Grand Totals	11.00%	11.36%	10.94%	10.76%
Net operating Income	$ 54,198	$ 51,432	$ 159,664	$ 150,442
Net operating Income: % of Grand Totals	14.18%	12.98%	13.23%	12.85%
Washington, DC [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Office	$ 100,666	$ 97,037	$ 300,742	$ 287,652
Rental Revenue: Residential	3,145	2,836	8,931	11,192
Rental Revenue: Hotel	0	0	0	0
Total revenue	$ 103,811	$ 99,873	$ 309,673	$ 298,844
Rental Revenue: % of Grand Totals	16.78%	16.01%	16.33%	16.15%
Rental Expenses: Office	$ 33,973	$ 31,985	$ 101,514	$ 98,660
Rental Expenses: Residential	1,082	1,049	3,255	5,106
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	$ 35,055	$ 33,034	$ 104,769	$ 103,766
Rental Expenses: % Of Grand Totals	14.81%	14.49%	15.20%	15.26%
Net operating Income	$ 68,756	$ 66,839	$ 204,904	$ 195,078
Net operating Income: % of Grand Totals	17.99%	16.88%	16.98%	16.67%

Segment Information (Schedule69

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	$ 76,753	$ 184,082	$ 355,114	$ 434,702
Preferred Stock Dividends / Distributions	(2,589)	(2,647)	(7,796)	(7,854)
Noncontrolling interest-common units of the Operating Partnership	(9,387)	(21,302)	(42,120)	(50,906)
Noncontrolling interest—redeemable preferred units	0	0	0	(6)
Noncontrolling interest in property partnerships	17,225	(115,240)	(53)	(139,712)
Losses from interest rate contracts	(140)	0	(140)	0
Losses from early extinguishments of debt	(371)	0	(371)	0
Interest expense	(104,641)	(108,727)	(314,953)	(326,018)
Depreciation and amortization expense	(203,748)	(153,015)	(516,371)	(475,082)
Impairment loss	(1,783)	0	(1,783)	0
Transaction costs	(249)	(254)	(1,187)	(789)
General and administrative expense	(25,165)	(20,944)	(79,936)	(72,019)
Gains (losses) from investments in securities	(976)	1,515	(1,713)	1,146
Interest and other income	(3,628)	(3,637)	(6,657)	(6,337)
Income from unconsolidated joint ventures	(1,464)	(2,647)	(5,489)	(20,559)
Development and management services income	(6,364)	(5,912)	(18,586)	(16,102)
Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	76,753	184,082	355,114	434,702
Preferred Stock Dividends / Distributions	2,589	2,647	7,796	7,854
Noncontrolling interest-common units of the Operating Partnership	9,387	21,302	42,120	50,906
Noncontrolling interest—redeemable preferred units	0	0	0	6
Noncontrolling interest in property partnerships	(17,225)	115,240	53	139,712
Losses from interest rate contracts	140	0	140	0
Losses from early extinguishments of debt	371	0	371	0
Interest expense	104,641	108,727	314,953	326,018
Depreciation and amortization expense	203,748	153,015	516,371	475,082
Impairment loss	1,783	0	1,783	0
Transaction costs	249	254	1,187	789
General and administrative expense	25,165	20,944	79,936	72,019
Gains on sales of real estate	12,983	199,479	80,606	294,563
Gains (losses) from investments in securities	976	(1,515)	1,713	(1,146)
Interest and other income	3,628	3,637	6,657	6,337
Income from unconsolidated joint ventures	1,464	2,647	5,489	20,559
Development and management services income	6,364	5,912	18,586	16,102
Net Operating Income	382,186	396,051	1,206,773	1,170,673
Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	91,306	207,626	408,540	491,847
Preferred Stock Dividends / Distributions	(2,589)	(2,647)	(7,796)	(7,854)
Noncontrolling interest—redeemable preferred units	0	0	0	(6)
Noncontrolling interest in property partnerships	17,225	(115,240)	(53)	(139,712)
Losses from interest rate contracts	(140)	0	(140)	0
Losses from early extinguishments of debt	(371)	0	(371)	0
Interest expense	(104,641)	(108,727)	(314,953)	(326,018)
Depreciation and amortization expense	(198,582)	(151,017)	(507,234)	(469,087)
Impairment loss	(1,783)	0	(1,783)	0
Transaction costs	(249)	(254)	(1,187)	(789)
General and administrative expense	(25,165)	(20,944)	(79,936)	(72,019)
Gains (losses) from investments in securities	(976)	1,515	(1,713)	1,146
Interest and other income	(3,628)	(3,637)	(6,657)	(6,337)
Income from unconsolidated joint ventures	(1,464)	(2,647)	(5,489)	(20,559)
Development and management services income	(6,364)	(5,912)	(18,586)	(16,102)
Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	91,306	207,626	408,540	491,847
Preferred Stock Dividends / Distributions	2,589	2,647	7,796	7,854
Noncontrolling interest—redeemable preferred units	0	0	0	6
Noncontrolling interest in property partnerships	(17,225)	115,240	53	139,712
Losses from interest rate contracts	140	0	140	0
Losses from early extinguishments of debt	371	0	371	0
Interest expense	104,641	108,727	314,953	326,018
Depreciation and amortization expense	198,582	151,017	507,234	469,087
Impairment loss	1,783	0	1,783	0
Transaction costs	249	254	1,187	789
General and administrative expense	25,165	20,944	79,936	72,019
Gains on sales of real estate	12,983	199,723	82,775	294,807
Gains (losses) from investments in securities	976	(1,515)	1,713	(1,146)
Interest and other income	3,628	3,637	6,657	6,337
Income from unconsolidated joint ventures	1,464	2,647	5,489	20,559
Development and management services income	6,364	5,912	18,586	16,102
Net Operating Income	$ 382,186	$ 396,051	$ 1,206,773	$ 1,170,673

Subsequent Events subsequent Ev

Subsequent Events subsequent Events (Details) - Subsequent Event [Member] $ in Millions	Oct. 20, 2016USD ($)ft²	Nov. 07, 2016ft²yr	Oct. 24, 2016apartments	Oct. 21, 2016	Oct. 01, 2016ft²
Subsequent Event [Line Items]
Number of apartment units | apartments			400
1265 Main Street [Member]
Subsequent Event [Line Items]
Ownership Percentage					50.00%
Net Rentable Area (in sf)					115,000
Metropolitian Square [Member]
Subsequent Event [Line Items]
Ownership Percentage	51.00%			20.00%
Net Rentable Area (in sf)	607,000
Contractual Sales Price | $	$ 282.4
Carrying Value of Debt Assumed in Sale | $	133.4
Unfunded leasing costs | $	$ 14.2
Ownership percentage in equity method investment, joint venture partner [Member] | Metropolitian Square [Member]
Subsequent Event [Line Items]
Ownership Percentage	49.00%			80.00%
145 Broadway [Member]
Subsequent Event [Line Items]
Net Rentable Area (in sf)		80,000
Term of Lease Signed (in years) | yr		15
build to suit [Member] | 145 Broadway [Member]
Subsequent Event [Line Items]
Net Rentable Area (in sf)		476,500
Future development [Member] | 145 Broadway [Member]
Subsequent Event [Line Items]
Net Rentable Area (in sf)		486,000
Retail Properties [ Member] | 145 Broadway [Member]
Subsequent Event [Line Items]
Net Rentable Area (in sf)		9,500