BioMed Realty L P 10-K 6 Feb 15 2014 FY Annual report Financial data

Document_Entity_Information

Document Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 06, 2015	Jun. 30, 2014
Entity Information [Line Items]
Entity Registrant Name	BioMed Realty Trust Inc
Entity Central Index Key	1289236
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		203,711,852
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$4,175,306,458
BIOMED REALTY, L.P.
Entity Information [Line Items]
Entity Registrant Name	BioMed Realty L P
Entity Central Index Key	1301932
Current Fiscal Year End Date	-19
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	Q4
Amendment Flag	FALSE

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014
Investments in real estate, net	$5,217,902	$5,416,575
Investments in unconsolidated partnerships	32,137	35,291
Parent Company
Income (Loss) from Continuing Operations, Per Basic and Diluted Share	$0.20
Investments in real estate, net	5,217,902	5,416,575
Investments in unconsolidated partnerships	32,137	35,291
Cash and cash equivalents	34,706	46,659
Accounts receivable, net	8,421	14,631
Accrued straight-line rents, net	173,779	163,716
Deferred leasing costs, net	198,067	219,713
Other assets	307,589	274,301
Total assets	5,972,601	6,170,886
Liabilities [Abstract]
Mortgage notes payable, net	709,324	496,757
Exchangeable senior notes	180,000	95,678
Unsecured senior notes, net	895,083	1,293,903
Unsecured senior term loans	758,786	749,326
Unsecured line of credit	128,000	84,000
Accounts payable, accrued expenses and other liabilities	314,383	381,280
Total liabilities	2,985,576	3,100,944
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common stock, $.01 par value, 250,000,000 shares authorized, 197,442,432 shares and 192,115,002 shares issued and outstanding at December 31, 2014 and December 31, 2013, respectively	1,921	1,975
Additional paid-in capital	3,554,558	3,649,235
Accumulated other comprehensive loss, net	-32,923	-2,214
Dividends in excess of earnings	-583,569	-645,983
Total stockholders' equity	2,939,987	3,003,013
Noncontrolling interests / Noncontrolling interests deficit	47,038	66,929
Total equity / capital	2,987,025	3,069,942
Total liabilities and equity / capital	5,972,601	6,170,886
BIOMED REALTY, L.P.
Income (Loss) from Continuing Operations, Per Basic and Diluted Share	$0.20
Investments in real estate, net	5,217,902	5,416,575
Investments in unconsolidated partnerships	32,137	35,291
Cash and cash equivalents	34,706	46,659
Accounts receivable, net	8,421	14,631
Accrued straight-line rents, net	173,779	163,716
Deferred leasing costs, net	198,067	219,713
Other assets	307,589	274,301
Total assets	5,972,601	6,170,886
Liabilities [Abstract]
Mortgage notes payable, net	709,324	496,757
Exchangeable senior notes	180,000	95,678
Unsecured senior notes, net	895,083	1,293,903
Unsecured senior term loans	758,786	749,326
Unsecured line of credit	128,000	84,000
Accounts payable, accrued expenses and other liabilities	314,383	381,280
Total liabilities	2,985,576	3,100,944
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Limited partners' capital, 5,405,474 and 5,415,974 units issued and outstanding at December 31, 2014 and December 31, 2013, respectively	45,708	45,600
General partner's capital, 197,442,432 and 192,115,002 units issued and outstanding at December 31, 2014 and December 31, 2013, respectively	2,970,650	3,002,135
Accumulated other comprehensive loss, net	-30,663	878
Total partners' capital	2,985,695	3,048,613
Noncontrolling interests / Noncontrolling interests deficit	1,330	21,329
Total equity / capital	2,987,025	3,069,942
Total liabilities and equity / capital	$5,972,601	$6,170,886

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parentheticals) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Parent Company
Common Stock, Par or Stated Value Per Share	0.01	0.01
Common Stock, Shares Authorized	250,000,000	250,000,000
Common Stock, Shares, Issued	197,442,432	192,115,002
BIOMED REALTY, L.P.
Limited Partners' Capital Account, Units Issued	5,405,474	5,415,974
Limited Partners' Capital Account, Units Outstanding	5,405,474	5,415,974
General Partners' Capital Account, Units Issued	197,442,432	192,115,002
General Partners' Capital Account, Units Outstanding	197,442,432	192,115,002
Common Stock | Parent Company
Common Stock, Shares Outstanding	197,442,432	192,115,002

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Expenses:
Equity in net loss of unconsolidated partnerships	$745	($905)	($1,389)
Income / (loss) from discontinued operations			-4,370
Parent Company
Revenues:
Rental	485,761	445,980	392,628
Tenant recoveries	162,394	141,634	120,793
Other revenue	26,454	49,700	4,746
Total revenues	674,609	637,314	518,167
Expenses:
Rental operations	214,502	184,073	152,219
Depreciation and amortization	254,341	245,000	196,844
General and administrative	49,315	44,175	38,025
Executive Severance	4,380
Acquisition-related expenses	3,831	5,282	13,077
Total expenses	526,369	478,530	400,165
Income from operations	148,240	158,784	118,002
Equity in net loss of unconsolidated partnerships	745	-905	-1,389
Interest expense, net	-95,280	-107,727	-99,608
Gain (Loss) on Sale of Properties	136,609	0	0
Other expense	11,154	-2,943	-872
Income / (loss) from continuing operations	201,468	47,209	16,133
Income / (loss) from discontinued operations			-4,370
Net income / (loss)	201,468	47,209	11,763
Net (income) / loss attributable to noncontrolling interests	-7,690	-565	62
Net income / (loss) attributable to the Company/Operating Partnership	193,778	46,644	11,825
Preferred stock dividends / unit distributions		-2,393	-14,603
Cost on redemption of preferred stock / units		-6,531
Net Income (Loss) Available to Common Stockholders	193,778	37,720	-2,778
Income (Loss) from Continuing Operations, Per Basic Share	$0.99
Income / (loss) from continuing operations per share / unit available to common stockholders / unitholders		$0.20
Income (Loss) from Continuing Operations, Per Diluted Share	$0.98
Loss from discontinued operations per share / unit available to common stockholders / unitholders			($0.03)
Earnings Per Share, Basic	$0.99
Net income / (loss) per share / unit available to common stockholders / unitholders		$0.20	($0.03)
Earnings Per Share, Diluted	$0.98
Weighted Average Number of Shares Outstanding, Basic	193,003,934	182,043,391	152,752,086
Weighted Average Number of Shares Outstanding, Diluted	207,232,960	186,397,022	155,700,387
BIOMED REALTY, L.P.
Revenues:
Rental	485,761	445,980	392,628
Tenant recoveries	162,394	141,634	120,793
Other revenue	26,454	49,700	4,746
Total revenues	674,609	637,314	518,167
Expenses:
Rental operations	214,502	184,073	152,219
Depreciation and amortization	254,341	245,000	196,844
General and administrative	49,315	44,175	38,025
Executive Severance	4,380
Acquisition-related expenses	3,831	5,282	13,077
Total expenses	526,369	478,530	400,165
Income from operations	148,240	158,784	118,002
Equity in net loss of unconsolidated partnerships	745	-905	-1,389
Interest expense, net	-95,280	-107,727	-99,608
Gain (Loss) on Sale of Properties	136,609	0	0
Other expense	11,154	-2,943	-872
Income / (loss) from continuing operations	201,468	47,209	16,133
Income / (loss) from discontinued operations			-4,370
Net income / (loss)	201,468	47,209	11,763
Net (income) / loss attributable to noncontrolling interests	-2,444	254	8
Net income / (loss) attributable to the Company/Operating Partnership	199,024	47,463	11,771
Preferred stock dividends / unit distributions		-2,393
Cost on redemption of preferred stock / units		($6,531)
Income (Loss) from Continuing Operations, Per Basic Share	$0.99
Income / (loss) from continuing operations per share / unit available to common stockholders / unitholders		$0.20
Income (Loss) from Continuing Operations, Per Diluted Share	$0.98
Loss from discontinued operations per share / unit available to common stockholders / unitholders			($0.03)
Earnings Per Share, Basic	$0.99
Net income / (loss) per share / unit available to common stockholders / unitholders		$0.20	($0.03)
Earnings Per Share, Diluted	$0.98
Weighted Average Number of Shares Outstanding, Basic	198,410,616	186,333,292	155,670,931
Weighted Average Number of Shares Outstanding, Diluted	207,232,960	186,396,309	155,670,931

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Comprehensive Income (Loss), Net of Tax	$39,313
Parent Company
Net income / (loss)	201,468	47,209	11,763
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	-1,639	395	3,611
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	-3,088	6,116	-5,144
Amortization of Other Deferred Charges	6,722	6,832	6,933
Other Comprehensive Income (Loss), Reclassification Adjustment for Write-down of Securities Included in Net Income, Net of Tax			545
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	-9,322		-38
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	46,640	10,907	-390
Other Comprehensive Income (Loss), Net of Tax	39,313	24,250	5,517
Comprehensive Income / loss, Net of Tax, Including Portion Attributable to Noncontrolling Interest	240,781	71,459	17,280
Comprehensive (income) / loss, Net of Tax, Attributable to Noncontrolling Interest	-16,294	-3,013	-42
Comprehensive income / (loss), Net of Tax, Attributable to Parent	224,487	68,446	17,238
BIOMED REALTY, L.P.
Net income / (loss)	201,468	47,209	11,763
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	-1,639	395	3,611
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	-3,088	6,116	-5,144
Amortization of Other Deferred Charges	6,722	6,832	6,933
Other Comprehensive Income (Loss), Reclassification Adjustment for Write-down of Securities Included in Net Income, Net of Tax			545
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	-9,322		-38
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	46,640	10,907	-390
Other Comprehensive Income (Loss), Net of Tax	39,313	24,250	5,517
Comprehensive Income / loss, Net of Tax, Including Portion Attributable to Noncontrolling Interest	240,781	71,459	17,280
Comprehensive (income) / loss, Net of Tax, Attributable to Noncontrolling Interest	-10,216	-1,582	8
Comprehensive income / (loss), Net of Tax, Attributable to Parent	230,565	69,877	17,288
Interest Rate Swaps | Parent Company
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	-3,088	6,116	-5,144
Interest Rate Swaps | BIOMED REALTY, L.P.
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	($3,088)

Consolidated_Statement_of_Equi

Consolidated Statement of Equity (USD $)		Parent Company	BIOMED REALTY, L.P.	Series A Preferred Stock	Series A Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss)/Income	Accumulated Other Comprehensive (Loss)/Income	Dividends in Excess of Earnings	Total Stockholders'/Partner's Equity	Total Stockholders'/Partner's Equity	Noncontrolling Interest	Noncontrolling Interest	Limited Partner	General Partner [Member]	Forward Starting Swaps	Forward Starting Swaps	Interest Rate Swaps	Interest Rate Swaps
In Thousands, except Share data				Parent Company	BIOMED REALTY, L.P.	Parent Company	Parent Company	Parent Company	BIOMED REALTY, L.P.	Parent Company	Parent Company	BIOMED REALTY, L.P.	Parent Company	BIOMED REALTY, L.P.	Common Stock	Common Stock	Parent Company	BIOMED REALTY, L.P.	Parent Company	BIOMED REALTY, L.P.
															BIOMED REALTY, L.P.	BIOMED REALTY, L.P.
Balance - value - period start at Dec. 31, 2011		$2,612,196	$2,612,196	$191,469	$191,469	$1,541	$2,773,994	($60,138)	($58,594)	($304,759)	$2,602,107	$2,612,440	$10,089	($244)	$10,332	$2,469,233
Balance - units - period start at Dec. 31, 2011					7,920,000										2,979,979	154,101,482
Balance - shares - period start at Dec. 31, 2011						154,101,482
Net issuances of unvested restricted common stock/OP units - shares						179,115										179,115
Net issuances of unvested restricted common stock/OP units - value		-3,528	-3,528			1	-3,529				-3,528	-3,528				-3,528
Conversion of OP units to common stock - shares						-47,221									-47,221	-47,221
Conversion of OP units to common stock - value						1					1		-1		-1	1
Vesting of share-based awards		11,530	11,530				11,530				11,530	11,530				11,530
Reallocation of equity to noncontrolling interests/limited partners							-146				-146		146		251	-251
Common stock dividends		-135,743								-135,743	-135,743
OP unit distributions		-2,591	-152,937		-14,603							-152,937	-2,591		-2,591	-135,743
Net income / (loss)		11,763	11,763		14,603					11,825	11,825	11,771	-62	-8	-54	-2,778
Preferred stock dividends/unit distributions		-14,603								-14,603	-14,603
Other Comprehensive Income (Loss), Foreign currency translation adjustment		3,611	3,611					3,543	3,611		3,543	3,611	68
Unrealized loss on equity securities		-390	-390					-382	-390		-382	-390	-8
Amortization of deferred interest costs			-6,933					6,803	-6,933		6,803	-6,933	130				6,933
Unrealized gain on derivative instruments, net		-5,144	-5,144					-5,048	-5,144		-5,048	-5,144	-96						-5,144
Other Comprehensive Income (Loss), Reclassification Adjustment for Write-down of Securities Included in Net Income, Net of Tax		545	545					535	545		535	545	10
Marketable Securities, Realized Gain (Loss)		-38	-38					-38	-38		-38	-38	0
Balance - value - period end at Dec. 31, 2012		2,484,541	2,484,541		191,469	1,543	2,781,849	-54,725	-53,077	-443,280	2,476,856	2,484,793	7,685	-252	7,937	2,338,464
Balance - units - period end at Dec. 31, 2012					7,920,000										2,932,758	154,327,818
Balance - shares - period end at Dec. 31, 2012						154,327,818
Net income / (loss)	[1]	17,458	17,458
Balance - value - period end at Mar. 31, 2013
Balance - value - period start at Dec. 31, 2012		2,484,541	2,484,541	191,469	191,469	1,543	2,781,849	-54,725	-53,077	-443,280	2,476,856	2,484,793	7,685	-252	7,937	2,338,464
Balance - units - period start at Dec. 31, 2012					7,920,000										2,932,758	154,327,818
Balance - shares - period start at Dec. 31, 2012						154,327,818
Stock Issued During Period, Shares, New Issues						31,855,000
Stock Issued During Period, Value, New Issues		641,097				319	640,778				641,097
Net issuances of unvested restricted common stock/OP units - shares						343,561										343,561
Net issuances of unvested restricted common stock/OP units - value		-5,050	-5,050			3	-5,053				-5,050	-5,050				-5,050
Conversion of OP units to common stock - shares						-20,396									-20,396	-20,396
Conversion of OP units to common stock - value							-87				-87		87		87	-87
Partners' Capital Account, Units, Redeemed					-7,920,000
Preferred Stock Redemption Premium		-198,000	-198,000	-191,469	-198,000					-6,531	-198,000	-198,000
Vesting of share-based awards		12,852	12,852				12,852				12,852	12,852				12,852
Stock Issued During Period, Units, Issued in Connection with Wexford Merger						5,568,227									336,960	5,568,227
Stock Issued During Period, Value, Issued in Connection with Wexford Merger		116,543	123,596			56	116,487				116,543	123,596			7,053	116,543
Noncontrolling Interest, Increase from Business Combination		48,571											48,571
Reallocation of equity to noncontrolling interests/limited partners							7,732				7,732		-7,732		-7,120	7,120
Common stock dividends		-178,009								-178,009	-178,009
OP unit distributions		-4,586	-184,988		-2,393							-184,988	-4,586		-4,586	-178,009
Net income / (loss)		47,209	47,209		8,924					46,644	46,644	47,463	565	-254	819	37,720
Preferred stock dividends/unit distributions		-2,393								-2,393	-2,393
Other Comprehensive Income (Loss), Foreign currency translation adjustment		395	395					362	395		362	395	33
Unrealized loss on equity securities		10,907	10,907					8,824	9,071		8,824	9,071	2,083	1,836
Amortization of deferred interest costs			6,832					6,665	6,832		6,665	6,832	167				6,832
Unrealized gain on derivative instruments, net		6,116	6,116					5,951	6,116		5,951	6,116	165						6,116
Balance - value - period end at Dec. 31, 2013		2,987,025	2,987,025	0	0	1,921	3,554,558	-32,923	-30,663	-583,569	2,939,987	2,985,695	47,038	1,330	45,708	2,970,650
Balance - units - period end at Dec. 31, 2013					0										5,415,974	192,115,002
Balance - shares - period end at Dec. 31, 2013						192,115,002
Balance - value - period start at Sep. 30, 2013
Net income / (loss)	[1]	10,576	10,576
Balance - value - period end at Dec. 31, 2013		2,987,025	2,987,025
Net income / (loss)	[1]	20,767	20,767
Balance - value - period end at Mar. 31, 2014
Balance - value - period start at Dec. 31, 2013		2,987,025	2,987,025			1,921	3,554,558	-32,923	-30,663	-583,569	2,939,987	2,985,695	47,038	1,330	45,708	2,970,650
Balance - units - period start at Dec. 31, 2013															5,415,974	192,115,002
Balance - shares - period start at Dec. 31, 2013						192,115,002
Stock Issued During Period, Value, New Issues		-49	-49				-49				-49	-49				-49
Net issuances of unvested restricted common stock/OP units - shares						361,553										361,553
Net issuances of unvested restricted common stock/OP units - value		-4,425	-4,425			4	-4,429				-4,425	-4,425				-4,425
Adjustments to Additional Paid in Capital, Warrant Issued		102	102				102				102	102				102
Stock Issued During Period, Shares, Conversion of Convertible Securities		4,955,377				4,955,377										4,955,377
Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments		84,234	84,234			50	84,184				84,234	84,234				84,234
Conversion of OP units to common stock - shares						-10,500									-10,500	-10,500
Conversion of OP units to common stock - value							-51				-51		51		51	-51
Vesting of share-based awards		15,763	15,763				15,763				15,763	15,763				15,763
Noncontrolling Interest, Increase from Business Combination		9,783	9,783										9,783	9,783
Reallocation of equity to noncontrolling interests/limited partners							-843				-843		843		1,675	-1,675
Common stock dividends		-256,192								-256,192	-256,192
OP unit distributions		-7,080	-263,272									-263,272	-7,080		-7,080	-256,192
Net income / (loss)		201,468	201,468							193,778	193,778	199,024	7,690	2,444	5,246	193,778
Other Comprehensive Income (Loss), Foreign currency translation adjustment		-1,639	-1,639					-1,596	-1,639		-1,596	-1,639	-43
Unrealized loss on equity securities		46,640	46,640					36,551	37,330		36,551	37,330	10,089	9,310
Amortization of deferred interest costs								6,544	-6,722		6,544	-6,722	178				6,722	-6,722
Unrealized gain on derivative instruments, net		-3,088	-3,088					-3,006	-3,088		-3,006	-3,088	-82						-3,088	-3,088
Marketable Securities, Realized Gain (Loss)		-9,322	-9,322					-7,784	-7,784		-7,784	-7,784	-1,538
Balance - value - period end at Dec. 31, 2014		3,069,942	3,069,942			1,975	3,649,235	-2,214	878	-645,983	3,003,013	3,048,613	66,929	21,329	45,600	3,002,135
Balance - units - period end at Dec. 31, 2014															5,405,474	197,442,432
Balance - shares - period end at Dec. 31, 2014						197,442,432
Balance - value - period start at Sep. 30, 2014
Net income / (loss)	[1]	144,627	144,627
Balance - value - period end at Dec. 31, 2014		$3,069,942	$3,069,942
[1]	The sum of quarterly financial data may vary from the annual data due to rounding.

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Adjustments to reconcile net income to net cash provided by operating activities
Allowance for doubtful accounts	$900	$900	$1,700
BIOMED REALTY, L.P.
Interest Paid, Capitalized	21,877	14,205
Operating Activities
Net income / (loss)	201,468	47,209	11,763
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	254,341	245,000	196,927
Allowance for doubtful accounts	900	931	1,656
Gain (Loss) on Sale of Properties	-136,609	0	0
Non-cash revenue adjustments	1,235	9,870	11,261
Other non-cash adjustments	7,947	9,095	19,027
Compensation expense related to restricted common stock and LTIP units / share-based payments	15,763	12,852	11,530
Distributions representing a return on capital from unconsolidated partnerships	1,986	237	1,202
Change in operating assets and liabilities
Accounts receivable	-6,724	-2,958	282
Accrued straight-line rents	-13,251	-22,027	-23,044
Deferred leasing costs	-15,576	-13,597	-13,993
Other assets	-24,395	-2,798	2,748
Accounts payable, accrued expenses and other liabilities	10,768	-4,025	18,876
Net cash provided by operating activities	297,853	279,789	238,235
Investing activities
Purchases of investments in real estate and related intangible assets	-133,983	-480,049	-366,492
Capital expenditures	-414,455	-252,128	-138,870
Proceeds from Sale of Property Held-for-sale	317,187
Contributions from historic tax credit transactions, net of deferred costs	48,789	34,585
Draws on construction loan receivable	-48,169	-124,048	-21,697
Proceeds from Collection of Loans Receivable	184,239
Contributions to unconsolidated partnerships, net	-5,433	-1,730	-2,410
Purchases of debt and equity securities	-31,808	-16,081	-8,645
Proceeds from the sale of debt and equity securities	14,202	6,232	132
Payments for (Proceeds from) Deposits on Real Estate Acquisitions	-24,213
Net cash used in investing activities	-93,644	-833,219	-537,982
Financing activities
Proceeds from issuance of OP units		641,097
Redemption of Series A preferred stock		-198,000
Payments of deferred loan costs	-3,546	-6,947	-5,937
Unsecured line of credit proceeds	885,000	805,000	596,000
Unsecured line of credit payments	-929,000	-795,000	-746,000
Mortgage notes proceeds	60,079	4,182
Principal payments on mortgage notes payable	-342,203	-115,542	-41,196
Proceeds from unsecured senior term loans		350,000	556,404
Unsecured senior term loan payments			-156,404
Proceeds from unsecured senior notes	397,632		247,815
Release of restriction of cash for repayment of debt		60,000
Dividends paid to common stockholders / unitholders	-260,132	-170,169	-132,796
Dividends paid to preferred stockholders / unitholders		-6,045	-14,601
Net cash provided by financing activities	-192,170	568,576	303,285
Effect of exchange rate changes on cash and cash equivalents	-86	-416	27
Net increase / (decrease) in cash and cash equivalents	11,953	14,730	3,565
Cash and cash equivalents at beginning of period	34,706	19,976	16,411
Cash and cash equivalents at end of period	46,659	34,706	19,976
Supplemental disclosure of cash flow information:
Cash paid during the period for interest (net of amounts capitalized of $21,877, $14,205 and $8,644 for the years ended December 31, 2014, 2013 and 2012, respectively)	85,245	94,938	81,868
Supplemental disclosure of non-cash investing and financing activities:
Accrual for preferred stock dividends / unit distributions declared			3,651
Accrual for common stock dividends / unit distributions declared	52,740	49,383	36,957
Accrued additions to real estate and related intangible assets	122,379	56,712	33,153
Mortgage notes assumed (includes premiums of $3,966, $8,671 and $1,802 for the years ended December 31, 2014, 2013 and 2012, respectively)	71,937	250,466	25,947
Equity issued in connection with Wexford merger and 320 Charles Street acquisition		165,114
Stock Issued During Period, Value, Conversion of Convertible Securities	84,322
equity issued in connection with 100 college street and 300 george street acquisition	21,740
Deposits applied for acquisitions			18,649
Debt Instrument, Unamortized Premium	3,966	8,671
Parent Company
Interest Paid, Capitalized	21,877	14,205
Operating Activities
Net income / (loss)	201,468	47,209	11,763
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	254,341	245,000	196,927
Allowance for doubtful accounts	900	931	1,656
Gain (Loss) on Sale of Properties	-136,609	0	0
Non-cash revenue adjustments	1,235	9,870	11,261
Other non-cash adjustments	7,947	9,095	19,027
Compensation expense related to restricted common stock and LTIP units / share-based payments	15,763	12,852	11,530
Distributions representing a return on capital from unconsolidated partnerships	1,986	237	1,202
Change in operating assets and liabilities
Accounts receivable	-6,724	-2,958	282
Accrued straight-line rents	-13,251	-22,027	-23,044
Deferred leasing costs	-15,576	-13,597	-13,993
Other assets	-24,395	-2,798	2,748
Accounts payable, accrued expenses and other liabilities	10,768	-4,025	18,876
Net cash provided by operating activities	297,853	279,789	238,235
Investing activities
Purchases of investments in real estate and related intangible assets	-133,983	-480,049	-366,492
Capital expenditures	-414,455	-252,128	-138,870
Proceeds from Sale of Property Held-for-sale	317,187
Contributions from historic tax credit transactions, net of deferred costs	48,789	34,585
Draws on construction loan receivable	-48,169	-124,048	-21,697
Proceeds from Collection of Loans Receivable	184,239
Contributions to unconsolidated partnerships, net	-5,433	-1,730	-2,410
Purchases of debt and equity securities	-31,808	-16,081	-8,645
Proceeds from the sale of debt and equity securities	14,202	6,232	132
Payments for (Proceeds from) Deposits on Real Estate Acquisitions	-24,213	0	0
Net cash used in investing activities	-93,644	-833,219	-537,982
Financing activities
Proceeds from common stock offering		668,553
Payment of offering costs		-27,456
Redemption of Series A preferred stock		-198,000
Payments of deferred loan costs	-3,546	-6,947	-5,937
Unsecured line of credit proceeds	885,000	805,000	596,000
Unsecured line of credit payments	-929,000	-795,000	-746,000
Mortgage notes proceeds	60,079	4,182
Principal payments on mortgage notes payable	-342,203	-115,542	-41,196
Proceeds from unsecured senior term loans		350,000	556,404
Unsecured senior term loan payments			-156,404
Proceeds from unsecured senior notes	397,632		247,815
Release of restriction of cash for repayment of debt		60,000
Distributions to operating partnership unit and LTIP unit holders	-7,246	-3,921	-2,498
Dividends paid to common stockholders / unitholders	-252,886	-166,248	-130,298
Dividends paid to preferred stockholders / unitholders		-6,045	-14,601
Net cash provided by financing activities	-192,170	568,576	303,285
Effect of exchange rate changes on cash and cash equivalents	-86	-416	27
Net increase / (decrease) in cash and cash equivalents	11,953	14,730	3,565
Cash and cash equivalents at beginning of period	34,706	19,976	16,411
Cash and cash equivalents at end of period	46,659	34,706	19,976
Supplemental disclosure of cash flow information:
Cash paid during the period for interest (net of amounts capitalized of $21,877, $14,205 and $8,644 for the years ended December 31, 2014, 2013 and 2012, respectively)	85,245	94,938	81,868
Supplemental disclosure of non-cash investing and financing activities:
Accrual for preferred stock dividends / unit distributions declared			3,651
Accrual for common stock dividends / unit distributions declared	51,335	48,029	36,268
Accrual for distributions declared for operating partnership unit and LTIP unit holders	1,405	1,354	689
Accrued additions to real estate and related intangible assets	122,379	56,712	33,153
Mortgage notes assumed (includes premiums of $3,966, $8,671 and $1,802 for the years ended December 31, 2014, 2013 and 2012, respectively)	71,937	250,466	25,947
Equity issued in connection with Wexford merger and 320 Charles Street acquisition		165,114
Stock Issued During Period, Value, Conversion of Convertible Securities	84,300
equity issued in connection with 100 college street and 300 george street acquisition	21,740
Deposits applied for acquisitions			18,649
Debt Instrument, Unamortized Premium	$3,966	$8,671

Organization_of_the_Parent_Com

Organization of the Parent Company and Description of Business	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization of the Parent Company and Description of Business	Organization of the Parent Company and Description of Business
	BioMed Realty Trust, Inc., a Maryland corporation (the “Parent Company”), operates as a fully integrated, self-administered and self-managed real estate investment trust (“REIT”) focused on acquiring, developing, owning, leasing and managing laboratory and office space for the life science industry principally through its subsidiary, BioMed Realty, L.P., a Maryland limited partnership (the “Operating Partnership” and together with the Parent Company referred to as the “Company”). The Company’s tenants primarily include biotechnology and pharmaceutical companies, scientific research institutions, government agencies and other entities involved in the life science industry. The Company’s properties are generally located in markets with well-established reputations as centers for scientific research, including Boston, San Francisco, San Diego, Maryland, New York/New Jersey, Pennsylvania, North Carolina, Seattle and Cambridge (United Kingdom) and research parks located near or adjacent to with universities and their related medical systems.
	The Parent Company is the sole general partner of the Operating Partnership and, as of December 31, 2014, owned a 97.4% interest in the Operating Partnership. The remaining 2.6% interest in the Operating Partnership is held by limited partners. Each partner’s percentage interest in the Operating Partnership is determined based on the number of operating partnership units and long-term incentive plan units (“LTIP units” and together with the operating partnership units, the “OP units”) owned as compared to total OP units (and potentially issuable OP units, as applicable) outstanding as of each period end and is used as the basis for the allocation of net income or loss to each partner.
	Information with respect to the square footage and the percent of rentable square feet leased to tenants is unaudited.

Basis_of_Presentation_and_Summ

Basis of Presentation and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies
	Principles of Consolidation
	The consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries, partnerships and limited liability companies it controls, and variable interest entities (“VIEs”) for which the Company has determined itself to be the primary beneficiary. All material intercompany transactions and balances have been eliminated. The Company consolidates entities the Company controls and records a noncontrolling interest for the portions not owned by the Company. Control is determined, where applicable, by the sufficiency of equity invested and the rights of the equity holders, and by the ownership of a majority of the voting interests, with consideration given to the existence of approval or veto rights granted to the minority stockholder. If the minority stockholder holds substantive participating rights, it overcomes the presumption of control by the majority voting interest holder. In contrast, if the minority stockholder simply holds protective rights (such as consent rights over certain actions), it does not overcome the presumption of control by the majority voting interest holder.
	Assets and liabilities of subsidiaries outside the United States with non-U.S. dollar functional currencies are translated into U.S. dollars using exchange rates as of the balance sheet dates. Income and expenses are translated using the average exchange rates for the reporting period. Foreign currency translation adjustments are recorded as a component of other comprehensive income. For the years ended December 31, 2014, 2013 and 2012, total revenues from properties outside the United States were $20.2 million, $18.2 million and $10.3 million, respectively, which represented 3.0%, 2.9% and 2.0% of the Company's total revenues during the respective periods. The Company’s net investments in properties outside the United States were $200.2 million, $190.2 million and $188.8 million at December 31, 2014, 2013 and 2012, respectively.
	Investments in Partnerships and Limited Liability Companies
	The Company evaluates its investments in limited liability companies and partnerships to determine whether such entities may be a VIE, and, if a VIE, whether the Company is the primary beneficiary. Generally, an entity is determined to be a VIE when either (1) the equity investors (if any) lack one or more of the essential characteristics of a controlling financial interest, (2) the equity investment at risk is insufficient to finance that entity's activities without additional subordinated financial support or (3) the equity investors have voting rights that are not proportionate to their economic interests and the activities of the entity involve or are conducted on behalf of an investor with a disproportionately small voting interest. The primary beneficiary is the entity that has both (1) the power to direct matters that most significantly impact the VIE's economic performance and (2) the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE. The Company considers a variety of factors in identifying the entity that holds the power to direct matters that most significantly impact the VIE's economic performance including, but not limited to, the ability to direct financing, leasing, construction and other operating decisions and activities. In addition, the Company considers the rights of other investors to participate in policy making decisions, to replace or remove the manager and to liquidate or sell the entity. The obligation to absorb losses and the right to receive benefits when a reporting entity is affiliated with a VIE must be based on ownership, contractual, and/or other pecuniary interests in that VIE. At December 31, 2014 and 2013, the Company determined that it is the primary beneficiary in six and five VIEs, respectively, (excluding certain VIEs through its ownership of Wexford Science and Technology, LLC and related entities (collectively, "Wexford") which are discussed below), consisting of single-tenant properties in which the tenant has a fixed-price purchase option, which are consolidated and reflected in the accompanying consolidated financial statements. Selected financial data of the VIEs at December 31, 2014 and 2013 consist of the following (in thousands):
		December 31,				December 31,
		2014				2013
	Investment in real estate, net	$	433,842			$	336,832
	Total assets	493,066				375,443
	Total debt	189,848				143,067
	Total liabilities	203,529				154,953
	If the foregoing conditions do not apply, the Company considers whether a general partner or managing member controls a limited partnership or limited liability company. The general partner in a limited partnership or managing member in a limited liability company is presumed to control that limited partnership or limited liability company. The presumption may be overcome if the limited partners or members have either (1) the substantive ability to dissolve the limited partnership or limited liability company or otherwise remove the general partner or managing member without cause or (2) substantive participating rights, which provide the limited partners or members with the ability to effectively participate in significant decisions that would be expected to be made in the ordinary course of the limited partnership’s or limited liability company’s business and thereby preclude the general partner or managing member from exercising unilateral control over the partnership or company. If these criteria are met and the Company is the general partner or the managing member, as applicable, the consolidation of the partnership or limited liability company is required.
	Except for investments that are consolidated, the Company accounts for investments in entities over which it exercises significant influence, but does not control, under the equity method of accounting. These investments are recorded initially at cost and subsequently adjusted for equity in earnings and cash contributions and distributions. Under the equity method of accounting, the Company’s net equity in the investment is reflected in the consolidated balance sheets and its share of net income or loss is included in the Company’s consolidated statements of operations.
	On a periodic basis, management assesses whether there are any indicators that the carrying value of the Company’s investments in unconsolidated partnerships or limited liability companies may be impaired on a more than temporary basis. An investment is impaired only if management’s estimate of the fair-value of the investment is less than the carrying value of the investment on a more than temporary basis. To the extent impairment has occurred, the loss is measured as the excess of the carrying value of the investment over the fair-value of the investment. Management does not believe that the carrying value of any of the Company’s unconsolidated investments in partnerships or limited liability companies was impaired as of December 31, 2014.
	Historic Tax Credits and New Market Tax Credits
	The Company is a party to certain contractual arrangements with tax credit investors ("TCIs") that were established to enable the TCIs to receive benefits of historic tax credits ("HTCs") and/or new market tax credits ("NMTCs") for certain properties owned by Wexford. During the years ended December 31, 2014 and 2013, Wexford owned ten and nine properties, respectively, that had syndicated HTCs or NMTCs, or both, to TCIs.
	Capital contributions are made by TCIs into special purpose entities that ultimately invest these funds in the entity that owns the subject property that generates the tax credits. The TCIs are allocated substantially all of the tax credits and hold only a noncontrolling interest in the economic risk and rewards of the special purpose entities. HTCs are delivered to the TCI upon substantial completion of the project. NMTCs are allowed for up to 39% of a qualified investment and are delivered to the TCI after the investment has been funded and spent on a qualified business. HTCs are subject to 20% recapture per year beginning one year after the completion of the historic rehabilitation of the subject property. NMTCs are subject to 100% recapture until the end of the seventh year following the qualifying investment. The Company has provided the TCIs with certain guarantees which protect the TCIs from loss should a tax credit recapture event occur. The contractual arrangements with the TCIs include a put/call provision whereby the Company may be obligated or entitled to repurchase the ownership interest of the TCIs in the special purpose entities at the end of the tax credit recapture period. The Company anticipates that either the TCIs will exercise their put rights or the Company will exercise its call rights; however, the Company believes that the put rights are more likely to be exercised.
	The portion of the TCI’s capital contribution that is attributed to the put is recorded at fair-value at inception and is accreted to the expected put price as interest expense in the consolidated statement of operations. At December 31, 2014 and 2013, approximately $5.2 million and $4.3 million of put liabilities were included in other liabilities in the consolidated balance sheets, respectively. The remaining balance of the TCI’s capital contribution is initially recorded in other liabilities in the consolidated balance sheets and will be relieved, upon delivery of the tax credit to the TCI, as a reduction in the carrying value of the subject property, net of allocated expenses. During the years ended December 31, 2014 and 2013, $48.8 million and $34.4 million of tax credits, net of costs and estimated put payments, were contributed by TCIs and were recorded as other liabilities in the consolidated balance sheets, respectively. During the years ended December 31, 2014 and 2013, $55.5 million and $22.4 million of tax credits have been delivered to the TCIs and were reclassified as a reduction of the carrying value of the subject property, respectively. Direct and incremental costs incurred in structuring the transaction are deferred and will be recognized as an increase in the cost basis of the subject property upon the recognition of the related tax credit as discussed above.
	At December 31, 2014 and 2013, the Company determined that certain special purpose entities owning one property and three properties, respectively, under development are VIEs, since there is insufficient capital to finance the remaining development activities without further subordinated financial support. The Company has determined it is the primary beneficiary of these VIEs, because it has the authority to direct the activities which most significantly impact their economic performance. Selected financial data of the VIEs at December 31, 2014 and 2013 consisted of the following (in thousands):
		December 31,			December 31,
		2014			2013
	Investment in real estate, net	$	2,507		$	177,901
	Total assets	24,478			198,968
	Total liabilities	7,467			60,197
	Investments in Real Estate, Net
	Investments in real estate are carried at depreciated cost. Depreciation and amortization are recorded on a straight-line basis over the estimated useful lives of the assets as follows:
	Buildings and improvements	Remaining useful life, not to exceed 40 years
	Tenant improvements	Shorter of the useful lives or the terms of the related leases
	Furniture, fixtures, and equipment (other assets)	Three to five years
	Acquired in-place leases	Non-cancelable term of the related lease
	Acquired management agreements	Non-cancelable term of the related agreement
	Investments in real estate, net consisted of the following (in thousands):
		December 31,				December 31,
		2014				2013
	Land	$	704,958			$	713,955
	Land under development	151,242				119,325
	Buildings and improvements	4,877,135				4,854,175
	Construction in progress	629,679				316,025
		6,363,014				6,003,480
	Accumulated depreciation	(946,439		)		(785,578		)
		$	5,416,575			$	5,217,902
	Purchase accounting is applied to the assets and liabilities of real estate properties in which the Company acquires a controlling interest or a partial interest. The fair-value of tangible assets of an acquired property (which includes land, buildings, and improvements) is determined by valuing the property as if it were vacant, and the “as-if-vacant” value is then allocated to land, buildings and improvements based on management’s determination of the fair-value of these assets. Factors considered by the Company in performing these analyses include an estimate of the carrying costs during the expected lease-up periods, current market conditions and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance and other operating expenses and estimates of lost rental revenue during the expected lease-up periods based on current market demand. Upon the acquisition of a controlling interest of an investment in an unconsolidated partnership, such partnership is consolidated and a gain is recognized equal to the amount in which the fair-value of the noncontrolling interest in such partnership exceeded its carrying value at the time of obtaining control.
	The aggregate value of other acquired intangible assets consisting of acquired in-place leases and acquired management agreements (see deferred leasing costs below) are recorded based on a variety of considerations including, but not necessarily limited to: (1) the value associated with avoiding the cost of originating the acquired in-place leases (i.e. the market cost to execute a lease, including leasing commissions and legal fees, if any); (2) the value associated with lost revenue related to tenant reimbursable operating costs estimated to be incurred during the assumed lease-up period (i.e. real estate taxes and insurance); and (3) the value associated with lost rental revenue from existing leases during the assumed lease-up period (see discussion of the recognition of acquired above-market and below-market leases in Revenue Recognition section below). The fair-value assigned to the acquired management agreements are recorded at the present value (using a discount rate which reflects the risks associated with the management agreements acquired) of the acquired management agreements with certain tenants of the acquired properties. The Company has also considered the existence of a tenant relationship intangible asset, but has not historically allocated any value to tenant relationships apart from acquired in-place leases. The values of in-place leases and management agreements are amortized to expense over the remaining non-cancelable period of the respective leases or agreements. If a lease were to be terminated or if termination is determined to be likely (e.g., in the case of a tenant bankruptcy) prior to its contractual expiration, amortization of all unamortized amounts related to that lease would be accelerated and such amounts written off.
	Costs incurred in connection with the development or construction of properties and improvements are capitalized. Capitalized costs include pre-construction costs essential to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other direct costs incurred during the period of development. The Company capitalizes costs on land and buildings under development until construction is substantially complete and the property is held available for occupancy. Determination of when a development project is substantially complete and when capitalization must cease involves a degree of judgment. The Company considers a construction project as substantially complete and held available for occupancy upon the completion of landlord-owned tenant improvements or when the lessee takes possession of the unimproved space for construction of its own improvements, but no later than one year from cessation of major construction activity. The Company ceases capitalization on the portion substantially completed and occupied or held available for occupancy, and capitalizes only those costs associated with any remaining portion under construction. Interest costs capitalized for the years ended December 31, 2014, 2013 and 2012 were $21.9 million, $14.2 million and $8.6 million, respectively. Payroll costs capitalized for the years ended December 31, 2014, 2013 and 2012 were $4.4 million, $3.6 million and $2.0 million, respectively. Costs associated with acquisitions of businesses are charged to expense.
	Repair and maintenance costs are charged to expense as incurred and significant replacements and betterments are capitalized. Repairs and maintenance costs include all costs that do not extend the useful life of an asset or increase its operating efficiency. Significant replacement and betterments represent costs that extend an asset’s useful life or increase its operating efficiency.
	Impairment of Long-Lived Assets and Long-Lived Assets to be Disposed
	The Company reviews long-lived assets and certain identifiable intangibles for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The review of recoverability is based on an estimate of the future undiscounted cash flows (excluding interest charges) expected to result from the long-lived asset’s use and eventual disposition. These cash flows consider factors such as expected future operating income, trends and prospects, as well as the effects of leasing demand, competition and other factors. If impairment exists due to the inability to recover the carrying value of a long-lived asset, an impairment loss is recorded to the extent that the carrying value exceeds the estimated fair-value of the property. The Company is required to make subjective assessments as to whether there are impairments in the values of its investments in long-lived assets. These assessments have a direct impact on the Company’s net income because recording an impairment loss results in an immediate negative adjustment to net income. The evaluation of anticipated cash flows is highly subjective and is based in part on assumptions regarding future occupancy, rental rates and capital requirements that could differ materially from actual results in future periods. Although the Company’s strategy is to hold its properties over the long-term, if the Company’s strategy changes or market conditions otherwise dictate an earlier sale date, an impairment loss may be recognized to reduce the property to the lower of the carrying amount or fair-value, and such loss could be material.
	In April 2012, the Company completed the exchange of a property for another real estate operating property. As a result, the property disposed of was reclassified as a discontinued operation. This property was written down to its estimated fair-value of $28.0 million, less costs to sell, which resulted in an impairment loss of $4.6 million that is included in loss from discontinued operations for the year ended December 31, 2012. The parties to the exchange determined and agreed upon the fair-value of the property received in the transaction, which the Company considers to be a Level 2 input in the fair-value hierarchy. See Note 12 for discussion of discontinued operations.
	Gain on Sale of Real Estate
	The Company recognizes gains on sale of real estate when a contract is in place, a closing has taken place, the buyer's initial and continuing involvement is adequate to demonstrate a commitment to pay for the property and the Company does not have a substantial involvement in the property. On December 9, 2014, the Company closed on the sale of the 9911 Belward Campus Drive property located in Rockville, Maryland for approximately $317.2 million in proceeds, net of selling costs, resulting in a gain on sale of approximately $136.6 million.
	Cash and Cash Equivalents
	Cash and cash equivalents consist of highly liquid investments with original maturities of three months or less. The Company maintains its cash at insured financial institutions. The combined account balances at each institution periodically exceed FDIC insurance coverage, and, as a result, there is a concentration of credit risk related to amounts in excess of FDIC limits. The Company believes that the risk is not significant.
	Deferred Leasing Costs, Net
	Leasing commissions and other direct costs associated with obtaining new or renewal leases are recorded at cost and amortized on a straight-line basis over the terms of the respective leases, with remaining terms ranging from less than one year to approximately 20 years as of December 31, 2014. Deferred leasing costs also include the net carrying value of acquired in-place leases and acquired management agreements.
	Deferred leasing costs, net at December 31, 2014 consisted of the following (in thousands):
		Balance at				Accumulated
		December 31, 2014				Amortization				Net
	Acquired in-place leases	$	415,389			$	(271,782	)		$	143,607
	Acquired management agreements	25,801				(22,328		)		3,473
	Deferred leasing and other direct costs	111,290				(38,657		)		72,633
		$	552,480			$	(332,767	)		$	219,713
	Deferred leasing costs, net at December 31, 2013 consisted of the following (in thousands):
		Balance at				Accumulated
	December 31, 2013				Amortization				Net
Acquired in-place leases	$	365,753			$	(233,935	)		$	131,818
Acquired management agreements	25,801				(20,053		)		5,748
Deferred leasing and other direct costs	91,142				(30,641		)		60,501
	$	482,696			$	(284,629	)		$	198,067
The estimated amortization expense for deferred leasing costs at December 31, 2014 was as follows (in thousands):
2015	$	37,121
2016	29,029
2017	26,596
2018	22,348
2019	17,571
Thereafter	87,048
Total	$	219,713
Revenue Recognition, Operating Expenses and Lease Terminations
The Company commences revenue recognition on its leases based on a number of factors. In most cases, revenue recognition under a lease begins when the lessee takes possession of or controls the physical use of the leased asset. Generally, this occurs on the lease commencement date. In determining what constitutes the leased asset, the Company evaluates whether the Company or the lessee is the owner, for accounting purposes, of the tenant improvements. If the Company is the owner, for accounting purposes, of the tenant improvements, then the leased asset is the finished space and revenue recognition begins when the lessee takes possession of the finished space, typically when the improvements are substantially complete. If the Company concludes that it is not the owner, for accounting purposes, of the tenant improvements (the lessee is the owner), then the leased asset is the unimproved space and any tenant improvement allowances funded under the lease are treated as lease incentives, which reduce revenue recognized on a straight-line basis over the remaining non-cancelable term of the respective lease. In these circumstances, the Company begins revenue recognition when the lessee takes possession of the unimproved space for the lessee to construct improvements. The determination of who is the owner, for accounting purposes, of the tenant improvements determines the nature of the leased asset and when revenue recognition under a lease begins. The Company considers a number of different factors to evaluate whether it or the lessee is the owner of the tenant improvements for accounting purposes. These factors include:
•	whether the lease stipulates how and on what a tenant improvement allowance may be spent;
•	whether the tenant or landlord retain legal title to the improvements;
•	the uniqueness of the improvements;
•	the expected economic life of the tenant improvements relative to the length of the lease;
•	the responsible party for construction cost overruns; and
•	who constructs or directs the construction of the improvements.
The determination of who owns the tenant improvements, for accounting purposes, is subject to significant judgment. In making that determination, the Company considers all of the above factors. However, no one factor is determinative in reaching a conclusion.
All leases are classified as operating leases and minimum rents are recognized on a straight-line basis over the term of the related lease. The excess of rents recognized over amounts contractually due pursuant to the underlying leases are included in accrued straight-line rents on the accompanying consolidated balance sheets and contractually due but unpaid rents are included in accounts receivable. Existing leases at acquired properties are reviewed at the time of acquisition to determine if contractual rents are above or below current market rents for the acquired property. An identifiable lease intangible asset or liability is recorded based on the present value (using a discount rate that reflects the risks associated with the acquired leases) of the difference between (1) the contractual amounts to be paid pursuant to the in-place leases and (2) the Company’s estimate of the fair market lease rates for the corresponding in-place leases at acquisition, measured over a period equal to the remaining non-cancelable term of the leases and any fixed rate renewal periods (based on the Company’s assessment of the likelihood that the renewal periods will be exercised). The capitalized above-market lease values are amortized as a reduction of rental revenue on a straight-line basis over the remaining non-cancelable terms of the respective leases. The capitalized below-market lease values are amortized as an increase to rental revenue on a straight-line basis over the remaining non-cancelable terms of the respective leases and any fixed-rate renewal periods, if applicable. If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off.
The impact of the straight-line rent revenue, acquired above and below market lease revenue, and lease incentive revenue consisted of the following (in thousands):
	Years Ended December 31,
	2014				2013				2012
Straight-line rent revenue	$	13,197			$	23,136			$	23,288
Acquired above-market lease revenue	(4,647		)		(11,913		)		(9,977		)
Acquired below-market lease revenue	6,061				4,325				1,684
Lease incentive revenue	(2,674		)		(2,295		)		(2,969		)
Net increase in revenue	$	11,937			$	13,253			$	12,026
Total estimated minimum rents under non-cancelable operating tenant leases in effect at December 31, 2014 were as follows (in thousands):
2015	$	451,321
2016	450,748
2017	433,538
2018	377,925
2019	336,180
Thereafter	2,300,692
Total	$	4,350,404
The estimated amortization for acquired above- and below-market lease revenue and lease incentive revenue at December 31, 2014 was as follows (in thousands):
	2015				2016				2017				2018				2019				Thereafter			Total
Amortization of:
Acquired above-market leases	$	(1,895	)		$	(1,307	)		$	(1,179	)		$	(1,132	)		$	(972	)		$	(4,722	)	$	(11,207	)
Acquired below-market leases	4,042				3,782				3,690				3,656				3,150				17,478			35,798
Lease incentive	(3,951		)		(3,863		)		(3,420		)		(1,615		)		(1,456		)		(10,109		)	(24,414		)
Rental operations expenses, consisting of real estate taxes, insurance and common area maintenance costs, are subject to recovery from tenants under the terms of lease agreements. Amounts recovered are dependent on several factors, including occupancy and lease terms. Revenues are recognized in the period the expenses are incurred. The reimbursements are recorded in revenues as tenant recoveries, and the expenses are recorded in rental operations expenses, as the Company is generally the primary obligor with respect to purchasing goods and services from third-party suppliers, has discretion in selecting the supplier and bears the credit risk.
On an ongoing basis, the Company evaluates the recoverability of tenant balances, including rents receivable, straight-line rents receivable, tenant improvements, deferred leasing costs and any acquisition intangibles. Factors considered by the Company as part of this evaluation include, among other things, the financial strength of the tenant and any guarantors, a review of publicly filed documents and analyst research reports, a review of the tenant's cash balance and estimated cash "burn" rate if the tenant's cash flow from operations is negative, and the tenant's payment history. When it is determined that the recoverability of tenant balances is not probable, an allowance for expected losses related to tenant receivables, including straight-line rents receivable is recorded as a charge to earnings. Upon the termination of a lease, the amortization of tenant improvements, deferred leasing costs and acquisition intangible assets and liabilities is accelerated to the expected termination date as a charge to their respective line items and tenant receivables are written off as a reduction of the allowance in the period in which the balance is deemed to be no longer collectible. For financial reporting purposes, a lease is treated as terminated upon a tenant filing for bankruptcy, when a space is abandoned and a tenant ceases rent payments, or when other circumstances indicate that termination of a tenant’s lease is probable (e.g., eviction). Lease termination fees are recognized in other income when the related leases are canceled, the amounts to be received are fixed and determinable and collectability is assured, and when the Company has no continuing obligation to provide services to such former tenants.
Allowance for Doubtful Accounts
The Company maintains an allowance for doubtful accounts for estimated losses resulting from the inability of tenants to make required rent and tenant recovery payments or defaults. The Company maintains an allowance for accrued straight-line rents. The determination of this allowance is based on the tenants’ payment history and current credit status. Bad debt expense included in rental operations expenses was approximately $900,000, $931,000 and $1.7 million for the years ended December 31, 2014, 2013 and 2012, respectively. The Company’s allowance for doubtful accounts included in accounts receivable, net and accrued straight line rent, net was approximately $2.4 million, $2.3 million and $4.2 million as of December 31, 2014, 2013 and 2012, respectively.
Investments
The Company, through its Operating Partnership, holds equity investments in certain publicly-traded companies and privately-held companies primarily involved in the life science industry. The Company may accept equity investments from tenants in lieu of cash rents, as prepaid rent pursuant to the execution of a lease, or as additional consideration for a lease termination. The Company does not acquire investments for trading purposes and, as a result, all of the Company’s investments in publicly-traded companies are considered “available-for-sale” and are recorded at fair-value. Changes in the fair-value of investments classified as available-for-sale are recorded in comprehensive income. The fair-value of the Company’s equity investments in publicly-traded companies is determined based upon the closing trading price of the equity security as of the balance sheet date, with unrealized gains and losses shown as a separate component of equity. Investments in privately-held companies are generally accounted for under the cost method, because the Company does not influence any operating or financial policies of the companies in which it invests. The classification of investments is determined at the time each investment is made, and such determination is reevaluated at each balance sheet date. The cost of investments sold is determined by the specific identification method, with net realized gains and losses included in other income. For all investments, if a decline in the fair-value of an investment below its carrying value is determined to be other-than-temporary, such investment is written down to its estimated fair-value with a non-cash charge to earnings. The factors that the Company considers in making these assessments include, but are not limited to, market prices, market conditions, available financing, prospects for favorable or unfavorable clinical trial results, new product initiatives and new collaborative agreements.
Investments in equity securities, which are included in other assets on the accompanying consolidated balance sheets, consisted of the following (in thousands):
	December 31,				December 31,
	2014				2013
Available-for-sale securities, historical cost	$	10,280			$	8,543
Unrealized gain, net	48,341				11,023
Available-for-sale securities, fair-value (1)	58,621				19,566
Privately-held securities, cost basis	43,428				18,485
Total equity securities	$	102,049			$	38,051
-1	Determination of fair-value is classified as Level 1 in the fair-value hierarchy based on the use of quoted prices in active markets.
The Company holds investments in available-for-sale securities of certain publicly-traded companies. Certain of these investments have fair-values less than the Company’s cost basis, net of previous other-than-temporary impairment in these securities due to decreases in their respective stock prices during the year ended December 31, 2014. However, management has the intent and ability to retain the investments for a period of time sufficient to allow for an anticipated recovery in their market value. Management will continue to periodically evaluate whether any investment, the fair-value of which is less than the Company’s cost basis, should be considered other-than-temporarily impaired. If other-than-temporary impairment is considered to exist, the related unrealized loss will be reclassified from accumulated other comprehensive loss and recorded as a reduction of net income.
The Company also holds investments in securities of certain privately-held companies and funds, which are recorded at cost basis due to the Company’s lack of control or significant influence over such companies and funds.
During the years ended December 31, 2014 and 2013, the Company recorded impairment charges of $2.0 million and $2.8 million, respectively. Impairment charges are included in other expense in the consolidated statements of operations and relate to the Company’s investments in two privately-held companies. Other than these investments there were no identified events or changes in circumstances that may have a significant adverse effect on the carrying value of the Company’s cost basis investments and therefore, no evaluation of impairment was performed during the year ended December 31, 2014 on the Company’s remaining cost basis investments.
Share-Based Payments
All share-based payments to employees are recognized in the consolidated statement of operations based on their fair-value. Through December 31, 2014, the Company had awarded restricted stock of the Parent Company and LTIP unit grants of the Operating Partnership under its incentive award plan, both of which are valued based on the closing market price of the underlying common stock on the date of grant, and had not granted any stock options. During the years ended December 31, 2014, 2013 and 2012, the Parent Company awarded performance units (the “Performance Units”) to certain of its executive officers. Each Performance Unit represents a contingent right to receive one share of the Parent Company’s common stock if vesting conditions are satisfied. The grant date fair-value of the Performance Units was estimated using a Monte Carlo simulation which considered the likelihood of achieving the vesting conditions (see Note 13 for further information on the fair-value of the Performance Units). The fair-value of all share-based payments is amortized to general and administrative expense and rental operations expense over the relevant service period, adjusted for anticipated forfeitures.
Assets and Liabilities Measured at Fair-Value
The Company measures financial instruments and other items at fair-value where required under GAAP, but has elected not to measure any additional financial instruments and other items at fair-value as permitted under fair-value option accounting guidance.
Fair-value measurement is determined based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering market participant assumptions in fair-value measurements, there is a fair-value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity’s own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy).
Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability, which are typically based on an entity’s own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair-value measurement is based on inputs from different levels of the fair-value hierarchy, the level in the fair-value hierarchy within which the entire fair-value measurement falls is based on the lowest level input that is significant to the fair-value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair-value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.
The Company has used interest rate swaps 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. The fair-values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. 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. In adjusting the fair-value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees.
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 itself and its counterparties. However, as of December 31, 2014, the Company has determined that the impact of the credit valuation adjustments on the overall valuation of its derivative positions is not significant. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair-value hierarchy (see Note 9).
The valuation of the Company’s investments in publicly-traded companies utilizes observable market-based inputs, based on the closing trading price of securities as of the balance sheet date, therefore, the Company has determined that valuations of available-for-sale securities are classified in Level 1 of the fair-value hierarchy.
No other assets or liabilities are measured at fair-value on a recurring basis, or have been measured at fair-value on a non-recurring basis subsequent to initial recognition, in the accompanying consolidated balance sheets as of December 31, 2014 and 2013.
Derivative Instruments
The Company records all derivatives on the consolidated balance sheets at fair-value. In determining the fair-value of its derivatives, the Company considers the credit risk of its counterparties and the Company. These counterparties are generally larger financial institutions engaged in providing a variety of financial services. These institutions generally face similar risks regarding adverse changes in market and economic conditions, including, but not limited to, fluctuations in interest rates, exchange rates, equity and commodity prices and credit spreads. The ongoing disruptions in the financial markets have heightened the risks to these institutions. While management believes that its counterparties will meet their obligations under the derivative contracts, it is possible that defaults may occur.
The accounting for changes in the fair-value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair-value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair-value hedges. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Derivatives may also be designated as hedges of the foreign currency exposure of a net investment in a foreign operation. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair-value of the hedged asset or liability that are attributable to the hedged risk in a fair-value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risks, even though hedge accounting does not apply or the Company elects not to apply hedge accounting.
For derivatives designated as cash flow hedges, the effective portion of changes in the fair-value of the derivative is initially reported in other comprehensive income (outside of earnings) and subsequently reclassified to earnings in the period in which the hedged transaction affects earnings. If charges relating to the hedged transaction are being deferred pursuant to redevelopment or development activities, the effective portion of changes in the fair-value of the derivative are also deferred in accumulated other comprehensive income on the consolidated balance sheet, and are amortized to the income statement once the deferred charges from the hedged transaction begin again to affect earnings. The ineffective portion of changes in the fair-value of the derivative is recognized directly in earnings. The Company assesses the effectiveness of each hedging relationship by comparing the changes in cash flows of the derivative hedging instrument with the changes in cash flows of the designated hedged item or transaction. For derivatives that are not classified as hedges, changes in the fair-value of the derivative are recognized directly in earnings in the period in which the change occurs.
The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of its debt funding and the use of derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known or expected cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings.
The Company’s primary objective in using derivatives is to add stability to interest expense and to manage its exposure to interest rate movements or other identified risks. To accomplish this objective, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying principal amount. During the years ended December 31, 2014, 2013 and 2012, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt and future variability in the interest-related cash flows from forecasted issuances of debt (see Note 9). The Company formally documents the hedging relationships for all derivative instruments, has historically accounted for its interest rate swap agreements as cash flow hedges, and does not use derivatives for trading or speculative purposes.
Equity Offering Costs
Underwriting commissions and offering costs are reflected as a reduction of proceeds.
Income Taxes of the Parent Company
The Parent Company has elected to be taxed as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended. The Parent Company believes it has qualified and continues to qualify as a REIT. A REIT is generally not subject to federal income tax on that portion of its taxable income that is distributed to its stockholders. Accordingly, no provision has been made for federal income taxes in the accompanying consolidated financial statements. REITs are subject to a number of organizational and operational requirements. If the Parent Company fails to qualify as a REIT in any taxable year, the Parent Company will be subject to federal income tax (including any applicable alternative minimum tax) and, in most of the states, state income tax on its taxable income at regular corporate tax rates. The Parent Company is subject to certain state and local taxes.
Income Taxes of the Operating Partnership
As a partnership, the allocated share of income of the Operating Partnership is included in the income tax returns of the general and limited partners. Accordingly, no accounting for income taxes is required in the accompanying consolidated financial statements. The Operating Partnership may be subject to certain state or local taxes on its income and property.
The Operating Partnership has formed certain taxable REIT subsidiaries (each a “TRS”) on behalf of the Parent Company. In general, each TRS may perform non-customary services for tenants, hold assets that the Parent Company cannot hold directly and, except for the operation or management of health care facilities or lodging facilities or the providing of any person, under a franchise, license or otherwise, rights to any brand name under which any lodging facility or health care facility is operated, may engage in any real estate or non-real estate related business. Each TRS is subject to corporate federal and state income taxes on its taxable income at regular corporate tax rates. There is no tax provision for any TRS for the periods presented in the accompanying consolidated statements of operations due to net operating losses incurred. No tax benefits have been recorded since it is not considered more likely than not that the deferred tax asset related to the net operating loss carryforwards will be utilized.
Dividends and Distributions
Earnings and profits, which determine the taxability of dividends and distributions to stockholders, will differ from income reported for financial reporting purposes due to the difference for federal income tax purposes in the treatment of revenue recognition, compensation expense, and in the estimated useful lives of real estate assets used to compute depreciation.
The income tax treatment for dividends was as follows:
	For the Years Ended December 31,
	2014							2013							2012
	Per Share				%			Per Share				%			Per Share				%
Common stock:
Ordinary income	$	0.5			38.46	%		$	0.94			100	%		$	0.63			74.12	%
Capital gain	0.8				61.54			—				—			—				—
Return of capital	—				—			—				—	%		0.22				25.88	%
Total	$	1.3			100	%		$	0.94			100	%		$	0.85			100	%
Preferred stock:
Ordinary income	$	—			—	%		$	0.76			100	%		$	1.84			100	%
Capital gain	—				—			—				—			—				—
Return of capital	—				—			—				—			—				—
Total	$	—			—	%		$	0.76			100	%		$	1.84			100	%
Construction Loan Receivable
The Company had a $255.0 million interest in a $355.0 million construction loan secured by first priority mortgages on a 1.1 million square foot laboratory, office and retail development project located in Boston, Massachusetts, which is 95% leased to Vertex Pharmaceuticals Incorporated to serve as its new corporate headquarters. As of December 31, 2013, the Company had invested approximately $151.8 million in the construction loan, which is included in other assets on the Company's consolidated balance sheet. In May 2014, the borrower repaid the then outstanding principal and accrued interest balance prior to maturity, of which the Company's portion was approximately $191.2 million. The Company also received prepayment fees of approximately $8.1 million, resulting in other revenue of $7.5 million, net of deferred loan fees write-offs.
Lease Termination
During the years ended December 31, 2014, 2013 and 2012, the Company recorded lease termination revenue, net of write-offs of lease intangibles, included in other revenue on the consolidated statement of operations of approximately $12.6 million, $42.8 million and $3.5 million, respectively. Lease termination revenue for the year ended December 31, 2014 primarily related to the early termination of leases at three of the Company's properties. Lease termination revenue for the year ended December 31, 2013 primarily related to the termination of a lease with Elan Corporation (“Elan”) at the Company’s Science Center at Oyster Point property for which Elan paid the Company $46.5 million, and the termination of a lease effective August 2013 with Merck at the Company's 320 Bent Street property for which Merck paid the Company $8.7 million in August 2012. Lease termination revenue for the year ended December 31, 2012 primarily related to the termination of the lease with Merck.
Management’s Estimates
Management has made a number of estimates and assumptions relating to the reporting of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reporting of revenue and expenses during the reporting period to prepare these consolidated financial statements in conformity with GAAP. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and reported amounts of revenue and expenses that are not readily apparent from other sources. Actual results could differ from those estimates under different assumptions or conditions.
New Accounting Pronouncement
In April 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2014-8, "Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity" ("ASU 2014-8"). ASU 2014-8 requires a disposal of a component to meet a higher threshold in order to be reported as a discontinued operation in an entity’s financial statements. The threshold is defined as a strategic shift that has, or will have, a major effect on an entity’s operations and financial results such as a disposal of a major geographical area or a major line of business. This new guidance is effective for the Company beginning in the first quarter of 2015, with early adoption permitted under certain circumstances. During the year ended December 31, 2014, the Company adopted the guidance early in connection with the sale of the 9911 Belward Campus Drive property, which was not determined to be a disposal of a major geographical area or a major line of business.

Equity_of_the_Parent_Company

Equity of the Parent Company	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Equity of the Parent Company	Equity of the Parent Company
	During the year ended December 31, 2014, the Parent Company issued restricted stock awards to the Company’s employees and directors totaling 565,107 and 22,555 shares of common stock, respectively (218,663 shares of common stock were surrendered to the Company and subsequently retired in lieu of cash payments for taxes due on the vesting of restricted stock and 13,114 shares were forfeited during the same period), which are included in the total of common stock outstanding as of the period end. In addition, 7,313 shares subject to performance-based vesting conditions originally issued in connection with the Company’s merger with Wexford were forfeited during the year ended December 31, 2014.
	The Parent Company awarded units to certain of its executive officers (the “Performance Units”), which represent a contingent right to receive one share of the Parent Company’s common stock if vesting conditions are satisfied. Outstanding Performance Units vest ratably over two or three year periods (each, a “Performance Period”) based upon the Parent Company’s total stockholder return relative to its peer group (the "Market Conditions"). The grant date fair-value of the Performance Units was estimated using a Monte Carlo simulation which considered the likelihood of achieving the Market Conditions. The expected value of the Performance Units on the grant date was determined by simulating the total stockholder return for the Parent Company and the peer group, considering the stock price variance for each of the peer group companies compared to each other and the Parent Company. In January 2013, 136,296 Performance Units, which were originally granted to certain executive officers in January 2012 and represent the maximum number of Performance Units that could have vested, were forfeited as a result of the Parent Company's total stockholder return relative to its peer group in 2012 being below the threshold for any payout. In January 2014, of the 136,296 Performance Units which were originally granted to certain executive officers in January 2012 and represent the maximum number of Performance Units that could have vested, 20,224 Performance Units vested (resulting in the issuance of 20,224 shares of the Parent Company’s common stock, of which 7,243 shares were surrendered to the Company and subsequently retired in lieu of cash payments for taxes due on such vesting) and the remaining 116,072 Performance Units were forfeited, based on the Parent Company’s total stockholder return relative to its peer group for the two years ending December 31, 2014. In January 2015, 136,296 Performance Units which were originally granted to certain executive officers in January 2012 and represent the maximum number of Performance Units that could have vested, were forfeited as a result of the Parent Company's total stockholder return relative to its peer group for the three years ending December 31, 2014 being below the threshold for any payout. In addition, of the 203,144 Performance Units which were originally granted to certain executive officers in January 2013 and represent the maximum number of Performance Units that could have vested, 13,215 Performance Units vested (resulting in the issuance of 13,215 shares of the Parent Company’s common stock, of which 5,504 shares were surrendered to the Company and subsequently retired in lieu of cash payments for taxes due on such vesting) and the remaining 189,929 Performance Units were forfeited, based on the Parent Company’s total stockholder return relative to its peer group for the two years ending December 31, 2014. During the year ended December 31, 2014, the Parent Company awarded 494,410 Performance Units which represent the maximum number of Performance Units that may vest over a three-year Performance Period ending December 31, 2016. The grant date fair-value of these awards of approximately $4.2 million will be recognized as compensation expense on a straight-line basis over each respective Performance Period. The total compensation remaining on the Performance Units granted during the year ended December 31, 2014 to be expensed in future periods over a weighted-average term of two years was $2.6 million as of December 31, 2014. No dividends will be paid or accrued on the Performance Units, and shares of the Parent Company's common stock will not be issued until vesting of the Performance Units occurs.
	Common Stock, Operating Partnership Units and LTIP Units
	As of December 31, 2014, the Company had outstanding 197,442,432 shares of the Parent Company’s common stock and 5,083,400 and 322,074 operating partnership and LTIP units, respectively (excluding operating partnership units held by the Parent Company). A share of the Parent Company’s common stock and the operating partnership and LTIP units have essentially the same economic characteristics as they share equally in the total net income or loss and distributions of the Operating Partnership.
	Dividends and Distributions
	The following table lists the dividends and distributions declared by the Parent Company and the Operating Partnership during the year ended December 31, 2014:
	Declaration Date		Securities Class		Amount Per				Period Covered		Dividend and		Dividend and
					Share/Unit						Distribution		Distribution Amount
											Payable Date
													(In thousands)
	March 17, 2014		Common stock and OP units		$	0.25			January 1, 2014 to March 31, 2014		April 15, 2014		$	49,479
	June 16, 2014		Common stock and OP units		$	0.25			April 1, 2014 to June 30, 2014		July 15, 2014		$	49,483
	September 15, 2014		Common stock and OP units		$	0.25			July 1, 2014 to September 30, 2014		October 15, 2014		$	50,714
	December 15, 2014		Common stock and OP units		$	0.26			October 1, 2014 to December 31, 2014		January 15, 2015		$	52,740
	In addition to the regularly scheduled quarterly dividends included in the table above, on December 11, 2014, the Company's Board of Directors declared a special cash dividend of $0.30 per share of common stock for a total distribution amount of approximately $60.9 million paid on December 29, 2014 to stockholders of record at the close of business on December 22, 2014.
	Total 2014 dividends and distributions declared on common stock and OP units through December 31, 2014 amounted to $263.3 million.
	Changes in Accumulated Other Comprehensive Loss by Component
		Foreign currency translation adjustments				Unrealized gains on available-for-sale securities				Gain / (loss) on derivative instruments				Total
	Balance at December 31, 2013	$	3,905			$	8,938			$	(45,766	)		$	(32,923	)
	Other comprehensive (loss) / income before reclassifications	(1,639		)		46,640				(6,625		)		38,376
	Amounts reclassified from accumulated other comprehensive income (1)	—				(9,322		)		10,259				937
	Net other comprehensive (loss) / income	(1,639		)		37,318				3,634				39,313
	Net other comprehensive loss / (income) allocable to noncontrolling interests	43				(8,551		)		(96		)		(8,604		)
	Balance as of December 31, 2014	$	2,309			$	37,705			$	(42,228	)		$	(2,214	)
	-1	Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of operations. See Note 9 for further information.
	Noncontrolling Interests
	Noncontrolling interests on the consolidated balance sheets of the Parent Company relate primarily to the OP units in the Operating Partnership that are not owned by the Parent Company. With respect to the noncontrolling interests in the Operating Partnership, noncontrolling interests with redemption provisions that permit the issuer to settle in either cash or common stock at the option of the issuer are further evaluated to determine whether temporary or permanent equity classification on the balance sheet is appropriate. Because the OP units comprising the noncontrolling interests contain such a provision, the Company evaluated this guidance, including the requirement to settle in unregistered shares, and determined that the OP units meet the requirements to qualify for presentation as permanent equity.
	The Company evaluates individual redeemable noncontrolling interests for the ability to continue to recognize the noncontrolling interest as permanent equity in the consolidated balance sheets. Any redeemable noncontrolling interest that fails to qualify as permanent equity will be reclassified as temporary equity and adjusted to the greater of (1) the carrying amount, or (2) its redemption value at the end of the period in which the determination is made.
	The redemption value of the OP units not owned by the Parent Company, had such units been redeemed at December 31, 2014, was approximately $116.9 million based on the average closing price of the Parent Company’s common stock of $21.62 per share for the ten consecutive trading days immediately preceding December 31, 2014.
	The following table shows the vested ownership interests in the Operating Partnership:
		December 31, 2014						December 31, 2013
		Operating Partnership Units and LTIP Units			Percentage of Total			Operating Partnership Units and LTIP Units			Percentage of Total
	BioMed Realty Trust	196,031,538			97.4	%		190,676,428			97.3	%
	Noncontrolling interest consisting of:
	Operating partnership and LTIP units held by employees and related parties	2,645,888			1.3	%		2,656,388			1.4	%
	Operating partnership and LTIP units held by third parties	2,627,145			1.3	%		2,627,145			1.3	%
	Total	201,304,571			100	%		195,959,961			100	%

Capital_of_the_Operating_Partn

Capital of the Operating Partnership	12 Months Ended
	Dec. 31, 2014
Partners' Capital [Abstract]
Capital of the Operating Partnership	Capital of the Operating Partnership
	Operating Partnership Units and LTIP Units
	As of December 31, 2014, the Operating Partnership had outstanding 202,525,832 operating partnership units and 322,074 LTIP units. The Parent Company owned 97.4% of the partnership interests in the Operating Partnership at December 31, 2014, is the Operating Partnership’s general partner and is responsible for the management of the Operating Partnership’s business. As the general partner of the Operating Partnership, the Parent Company effectively controls the ability to issue common stock of the Parent Company upon a limited partner’s notice of redemption. In addition, the Parent Company has generally acquired OP units upon a limited partner’s notice of redemption in exchange for shares of its common stock. The redemption provisions of OP units owned by limited partners that permit the Parent Company to settle in either cash or common stock at the option of the Parent Company are further evaluated in accordance with applicable accounting guidance to determine whether temporary or permanent equity classification on the balance sheet is appropriate. The Operating Partnership evaluated this guidance, including the requirement to settle in unregistered shares, and determined that these OP units meet the requirements to qualify for presentation as permanent equity.
	LTIP units represent a profits interest in the Operating Partnership for services rendered or to be rendered by the LTIP unit holder in its capacity as a partner, or in anticipation of becoming a partner, in the Operating Partnership. Upon the occurrence of specified events, LTIP units may over time achieve full parity with common units of the Operating Partnership for all purposes. Upon achieving full parity, LTIP units may be redeemed for an equal number of the Parent Company’s common stock or cash, at the Parent Company’s election.
	The redemption value of the OP units owned by the limited partners, not including the Parent Company, had such units been redeemed at December 31, 2014, was approximately $116.9 million based on the average closing price of the Parent Company’s common stock of $21.62 per share for the ten consecutive trading days immediately preceding December 31, 2014.
	Changes in Accumulated Other Comprehensive Income / (Loss) by Component
		Foreign currency translation adjustments			Unrealized gains on available- for-sale securities			Gain / (loss) on derivative instruments			Total
	Balance at December 31, 2013	$	4,006		$	9,186		$	(43,855	)	$	(30,663	)
	Other comprehensive (loss) / income before reclassifications	(1,639		)	46,640			(6,625		)	38,376
	Amounts reclassified from accumulated other comprehensive income (1)	—			(9,322		)	10,259			937
	Net other comprehensive (loss) / income	(1,639		)	37,318			3,634			39,313
	Net other comprehensive income allocable to noncontrolling interest	$	—		$	(7,772	)	$	—		$	(7,772	)
	Balance as of December 31, 2014	$	2,367		$	38,732		$	(40,221	)	$	878
	-1	Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of operations. See Note 9 for further information.

Debt

Debt	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Debt Disclosure	Debt
	Debt of the Parent Company
	The Parent Company does not hold any indebtedness. All debt is held directly or indirectly by the Operating Partnership; however, the Parent Company has guaranteed the Operating Partnership’s Exchangeable Senior Notes due 2030 (the “Exchangeable Senior Notes”), Unsecured Senior Notes due 2016 (the “Notes due 2016”), Unsecured Senior Notes due 2019 (the "Notes due 2019"), Unsecured Senior Notes due 2020 (the “Notes due 2020”), Unsecured Senior Notes due 2022 (the “Notes due 2022”), Unsecured Senior Term Loan due 2017 (the “Term Loan due 2017”), Unsecured Senior Term Loan due 2018 (the “Term Loan due 2018”) and unsecured line of credit.
	Debt of the Operating Partnership
	The following is a summary of the Operating Partnership’s outstanding consolidated debt as of December 31, 2014 and December 31, 2013 (dollars in thousands):
		Stated Interest Rate		Effective Interest Rate		Principal Balance
						December 31,			December 31,			Maturity Date
						2014			2013
	Mortgage Notes Payable
	9900 Belward Campus Drive	5.64	%	3.99	%	$	10,486		$	10,631		July 1, 2017
	9901 Belward Campus Drive	5.64	%	3.99	%	12,913			13,091			July 1, 2017
	Center for Life Science | Boston (1)	7.75	%	7.75	%	—			334,447			June 30, 2014
	100 College Street (2)	2.4	%	2.4	%	82,210			—			August 2, 2016
	4320 Forest Park Avenue	4	%	2.7	%	21,000			21,000			June 30, 2015
	300 George Street (2)	6.2	%	4.91	%	45,052			—			July 1, 2025
	Hershey Center for Applied Research	6.15	%	4.71	%	12,938			13,449			May 5, 2027
	500 Kendall Street (Kendall D)	6.38	%	5.45	%	55,545			57,927			December 1, 2018
	Shady Grove Road	5.97	%	5.97	%	141,131			143,067			September 1, 2016
	University of Maryland BioPark I	5.93	%	4.69	%	16,056			16,752			May 15, 2025
	University of Maryland BioPark II	5.2	%	4.33	%	61,905			62,946			September 5, 2021
	University of Maryland BioPark Garage	5.2	%	4.33	%	4,660			4,738			September 1, 2021
	University of Miami Life Science & Technology Park	4	%	2.89	%	20,000			20,000			February 1, 2016
						483,896			698,048
	Unamortized premiums					12,861			11,276
	Mortgage notes payable, net					496,757			709,324
	Exchangeable Senior Notes	3.75	%	3.75	%	95,678			180,000			January 30, 2015
	Notes due 2016	3.85	%	3.99	%	400,000			400,000			April 15, 2016
	Notes due 2019	2.63	%	2.72	%	400,000			—			May 1, 2019
	Notes due 2020	6.13	%	6.27	%	250,000			250,000			April 15, 2020
	Notes due 2022	4.25	%	4.36	%	250,000			250,000			July 15, 2022
						1,300,000			900,000
	Unamortized discounts					(6,097		)	(4,917		)
	Unsecured senior notes, net					1,293,903			895,083
	Term Loan due 2017 - U.S. dollar (3)	1.57	%	2.39	%	243,596			243,596			March 30, 2017
	Term Loan due 2017 - GBP (3)	1.9	%	2.14	%	155,730			165,190			March 30, 2017
	Term Loan due 2018	1.36	%	1.67	%	350,000			350,000			March 24, 2018
	Unsecured senior term loans					749,326			758,786
	Unsecured line of credit (4)	1.27	%	1.27	%	84,000			128,000			March 24, 2018
	Total consolidated debt					$	2,719,664		$	2,671,193
	-1	On April 1, 2014, the Operating Partnership repaid in full the mortgage loan secured by the Company's Center for Life Science | Boston property prior to its scheduled maturity date.
	-2	Mortgage notes payable assumed on April 4, 2014 in connection with the acquisition of the related properties.
	-3	In August 2012, the Operating Partnership converted approximately $156.4 million of outstanding borrowings into British pounds sterling (“GBP”) equal to £100.0 million, which was designated as a net investment hedge to mitigate the risk of fluctuations in foreign currency exchange rates. The principal balance represents the U.S. dollar amount based on the exchange rates of $1.56 to £1.00 and $1.65 to £1.00 at December 31, 2014 and December 31, 2013, respectively. The effective interest rate includes the impact of interest rate swap agreements (see Note 9 for further discussion of interest rate swap agreements).
	-4	At December 31, 2014, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $816.0 million.
	Mortgage Notes Payable, net
	The net carrying value of properties (investments in real estate) secured by the Operating Partnership’s mortgage notes payable was approximately $1.4 billion and $1.2 billion at December 31, 2014 and 2013, respectively.
	Premiums were recorded upon assumption of the mortgage notes payable at the time of the related property acquisition to account for above-market interest rates. Amortization of these premiums is recorded as a reduction to interest expense over the remaining term of the respective note using a method that approximates the effective-interest method.
	Exchangeable Senior Notes
	On January 11, 2010, the Operating Partnership issued $180.0 million aggregate principal amount of its Exchangeable Senior Notes. The Exchangeable Senior Notes are general senior unsecured obligations of the Operating Partnership and rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership. Interest at a rate of 3.75% per annum is payable on January 15 and July 15 of each year, beginning on July 15, 2010, until the stated maturity date of January 15, 2030. The terms of the Exchangeable Senior Notes are governed by an indenture, dated January 11, 2010, among the Operating Partnership, as issuer, the Parent Company, as guarantor, and U.S. Bank National Association, as trustee. The Exchangeable Senior Notes contain an exchange settlement feature, which provides that the Exchangeable Senior Notes may, at any time prior to the close of business on the second scheduled trading day preceding the maturity date, be exchangeable for shares of the Parent Company’s common stock at the then applicable exchange rate. As the exchange feature for the Exchangeable Senior Notes must be settled in the common stock of the Parent Company, accounting guidance applicable to convertible debt instruments that permit the issuer to settle all or a portion of the exchange feature in cash upon conversion does not apply. The initial exchange rate was 55.0782 shares per $1,000 principal amount of Exchangeable Senior Notes, representing an exchange price of approximately $18.16 per share of the Parent Company’s common stock. If certain designated events occur on or prior to January 15, 2015 and a holder elects to exchange Exchangeable Senior Notes in connection with any such transaction, the Company will increase the exchange rate by a number of additional shares of the Parent Company’s common stock based on the date the transaction becomes effective and the price paid per share of the Parent Company’s common stock in the transaction, as set forth in the indenture governing the Exchangeable Senior Notes. The exchange rate for the Exchangeable Senior Notes may be adjusted under certain circumstances, including the payment of cash dividends in excess of $0.14 per share of common stock. The increase in the quarterly cash dividend through 2014 resulted in an increase in the exchange rate of the Exchangeable Senior Notes to 60.2441 shares per $1,000 principal amount of Exchangeable Senior Notes (a conversion value of $16.60 per share), effective as of December 29, 2014, the Company’s ex-dividend date for the fourth quarter 2014 dividend.
	The Operating Partnership may redeem the Exchangeable Senior Notes, in whole or in part, at any time to preserve the Parent Company’s status as a REIT or at any time on or after January 21, 2015 for cash at 100% of the principal amount plus accrued and unpaid interest. The holders of the Exchangeable Senior Notes have the right to require the Operating Partnership to repurchase the Exchangeable Senior Notes, in whole or in part, for cash on each of January 15, 2015, January 15, 2020 and January 15, 2025, or upon the occurrence of a designated event, in each case for a repurchase price equal to 100% of the principal amount of the Exchangeable Senior Notes plus accrued and unpaid interest. The terms of the indenture for the Exchangeable Senior Notes do not require compliance with any financial covenants.
	During the year ended December 31, 2014, at the request of the holders that exercised their exchange right pursuant to the terms of the Operating Partnership's Exchangeable Senior Notes, the Parent Company issued 4,955,377 shares of its common stock in exchange for approximately $84.3 million in aggregate principal amount of the Exchangeable Senior Notes. On December 12, 2014, the Operating Partnership issued an offer to repurchase, at the option of each of the holders, any and all of the outstanding Exchangeable Senior Notes. On December 12, 2014 the Company also announced that the Operating Partnership intended to redeem all of the outstanding Exchangeable Senior Notes on January 30, 2015. Subsequent to December 31, 2014, the Parent Company issued 5,764,026 shares of its common stock in exchange for the remaining $95.7 million in aggregate principal amount of the Exchangeable Senior Notes at the request of the holders.
	Unsecured Senior Notes due 2016, net
	On March 30, 2011, the Operating Partnership issued $400.0 million aggregate principal amount of its Notes due 2016. The purchase price paid by the underwriters was 99.365% of the principal amount and the Notes due 2016 have been recorded on the consolidated balance sheet net of the discount. The Notes due 2016 are senior unsecured obligations of the Operating Partnership and rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership. However, the Notes due 2016 are effectively subordinated to the Operating Partnership’s existing and future mortgages and other secured indebtedness (to the extent of the value of the collateral securing such indebtedness) and to all existing and future preferred equity and liabilities, whether secured or unsecured, of the Operating Partnership’s subsidiaries, including guarantees provided by the Operating Partnership’s subsidiaries under the Operating Partnership’s unsecured line of credit. Interest at a rate of 3.85% per year is payable on April 15 and October 15 of each year, beginning on October 15, 2011, until the stated maturity date of April 15, 2016. The terms of the Notes due 2016 are governed by a base indenture and supplemental indenture, each dated March 30, 2011, among the Operating Partnership, as issuer, the Parent Company, as guarantor, and U.S. Bank National Association, as trustee.
	The Operating Partnership may redeem the Notes due 2016, in whole or in part, at any time for cash at a redemption price equal to the greater of (1) 100% of the principal amount of the Notes due 2016 being redeemed; or (2) the sum of the present values of the remaining scheduled payments of principal and interest thereon discounted to the redemption date on a semi-annual basis at the adjusted treasury rate plus 30 basis points, plus in each case, accrued and unpaid interest.
	The terms of the indenture for the Notes due 2016 require compliance with various financial covenants, including limits on the amount of total leverage and secured debt maintained by the Operating Partnership and which require the Operating Partnership to maintain minimum levels of debt service coverage. Management believes that it was in compliance with these covenants as of December 31, 2014.
	Unsecured Senior Notes due 2019, net
	On April 23, 2014 the Operating Partnership issued $400.0 million aggregate principal amount of its Notes due 2019. The purchase price paid by the initial purchasers was 99.408% of the principal amount and the Notes due 2019 have been recorded on the consolidated balance sheet net of the discount. The Notes due 2019 are senior unsecured obligations of the Operating Partnership and rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership. However, the Notes due 2019 are effectively subordinated to the Operating Partnership’s existing and future mortgages and other secured indebtedness (to the extent of the value of the collateral securing such indebtedness) and to all existing and future preferred equity and liabilities, whether secured or unsecured, of the Operating Partnership’s subsidiaries, including guarantees provided by the Operating Partnership’s subsidiaries under the Company’s unsecured line of credit. Interest at a rate of 2.625% per year is payable on May 1 and November 1 of each year, beginning on November 1, 2014, until the stated maturity date of May 1, 2019. The terms of the Notes due 2019 are governed by a base indenture and supplemental indenture, dated March 30, 2011 and April 23, 2014, respectively, among the Operating Partnership, as issuer, the Parent Company, as guarantor, and U.S. Bank National Association, as trustee.
	The Operating Partnership may redeem the Notes due 2019, in whole or in part, at any time for cash at a redemption price equal to the greater of (1) 100% of the principal amount of the Notes due 2019 being redeemed; or (2) the sum of the present values of the remaining scheduled payments of principal and interest thereon discounted to the redemption date on a semi-annual basis at the adjusted treasury rate plus 20 basis points, plus in each case, accrued and unpaid interest.
	The terms of the indenture for the Notes due 2019 require compliance with various financial covenants, including limits on the amount of total leverage and secured debt maintained by the Operating Partnership and which require the Operating Partnership to maintain minimum levels of debt service coverage. Management believes that it was in compliance with these covenants as of December 31, 2014.
	Unsecured Senior Notes due 2020, net
	On April 29, 2010, the Operating Partnership issued $250.0 million aggregate principal amount of its Notes due 2020. The purchase price paid by the initial purchasers was 98.977% of the principal amount and the Notes due 2020 have been recorded on the consolidated balance sheet net of the discount. The Notes due 2020 are senior unsecured obligations of the Operating Partnership and rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership. However, the Notes due 2020 are effectively subordinated to the Operating Partnership’s existing and future mortgages and other secured indebtedness (to the extent of the value of the collateral securing such indebtedness) and to all existing and future preferred equity and liabilities, whether secured or unsecured, of the Operating Partnership’s subsidiaries, including guarantees provided by the Operating Partnership’s subsidiaries under the Company’s unsecured line of credit. Interest at a rate of 6.125% per year is payable on April 15 and October 15 of each year, beginning on October 15, 2010, until the stated maturity date of April 15, 2020. The terms of the Notes due 2020 are governed by an indenture, dated April 29, 2010, among the Operating Partnership, as issuer, the Parent Company, as guarantor, and U.S. Bank National Association, as trustee.
	The Operating Partnership may redeem the Notes due 2020, in whole or in part, at any time for cash at a redemption price equal to the greater of (1) 100% of the principal amount of the Notes due 2020 being redeemed; or (2) the sum of the present values of the remaining scheduled payments of principal and interest thereon discounted to the redemption date on a semi-annual basis at the adjusted treasury rate plus 40 basis points, plus in each case, accrued and unpaid interest.
	The terms of the indenture for the Notes due 2020 require compliance with various financial covenants, including limits on the amount of total leverage and secured debt maintained by the Operating Partnership and which require the Operating Partnership to maintain minimum levels of debt service coverage. Management believes that it was in compliance with these covenants as of December 31, 2014.
	On January 12, 2011, in accordance with the registration rights agreement entered into among the Company, the Operating Partnership and the initial purchasers of the Notes due 2020, the Operating Partnership completed its exchange offer to exchange all of the outstanding unregistered Notes due 2020 for an equal principal amount of a new issue of 6.125% Senior Notes due 2020 pursuant to an effective registration statement on Form S-4 filed with the Securities and Exchange Commission. A total of $250.0 million aggregate principal amount of the original Notes due 2020, representing 100% of the outstanding principal amount of the original Notes due 2020, was tendered and received prior to the expiration of the exchange offer. The terms of the Notes due 2020 are substantially identical to the original Notes due 2020, except for transfer restrictions and registration rights relating to the original Notes due 2020.
	Unsecured Senior Notes due 2022, net
On June 28, 2012, the Operating Partnership issued $250.0 million aggregate principal amount of its Notes due 2022. The purchase price paid by the underwriters was 99.126% of the principal amount and the Notes due 2022 have been recorded on the consolidated balance sheet net of the discount. The Notes due 2022 are senior unsecured obligations of the Operating Partnership and rank equally in right of payment with all other senior unsecured indebtedness of the Operating Partnership. However, the Notes due 2022 are effectively subordinated to the Operating Partnership’s existing and future mortgages and other secured indebtedness (to the extent of the value of the collateral securing such indebtedness) and to all existing and future preferred equity and liabilities, whether secured or unsecured, of the Operating Partnership’s subsidiaries, including guarantees provided by the Operating Partnership’s subsidiaries under the Operating Partnership’s unsecured line of credit. Interest at a rate of 4.25% per year is payable on January 15 and July 15 of each year, beginning on January 15, 2013, until the stated maturity date of July 15, 2022. The terms of the Notes due 2022 are governed by a base indenture and supplemental indenture, dated March 30, 2011 and June 28, 2012, respectively, among the Operating Partnership, as issuer, the Parent Company, as guarantor, and U.S. Bank National Association, as trustee.
The Operating Partnership may redeem the Notes due 2022, in whole or in part, at any time for cash at a redemption price equal to the greater of (1) 100% of the principal amount of the Notes due 2022 being redeemed; or (2) the sum of the present values of the remaining scheduled payments of principal and interest thereon discounted to the redemption date on a semi-annual basis at the adjusted treasury rate plus 45 basis points, plus in each case, accrued and unpaid interest.
The terms of the indenture for the Notes due 2022 require compliance with various financial covenants, including limits on the amount of total leverage and secured debt maintained by the Operating Partnership and which require the Operating Partnership to maintain minimum levels of debt service coverage. Management believes that it was in compliance with these covenants as of December 31, 2014.
Unsecured Senior Term Loan due 2017
Term Loan due 2017 - U.S. dollar
On March 30, 2012, the Operating Partnership entered into the $400.0 million Term Loan due 2017 with KeyBank National Association (“KeyBank”) as administrative agent and co-lead arranger, Wells Fargo Securities, LLC as co-lead arranger and Wells Fargo Bank National Association as co-syndication agent, U.S. Bank National Association as co-syndication agent and co-lead arranger and other lenders. The Term Loan due 2017 has a maturity date of March 30, 2017. Subject to the administrative agent’s reasonable discretion, the Operating Partnership may increase the amount of the borrowings to $500.0 million under the Term Loan due 2017 upon satisfying certain conditions. Borrowings under the Term Loan due 2017 are guaranteed by the Parent Company.
Borrowings for the U.S. dollar-denominated debt under the Term Loan due 2017 bear interest at a floating rate equal to, at the Operating Partnership’s option, either (1) reserve adjusted U.S. dollar-LIBOR plus a spread which ranges from 115 to 205 basis points, depending on the Parent Company’s credit ratings, or (2) the highest of (a) the prime rate then in effect plus a spread which ranges from 15 to 120 basis points, (b) the federal funds rate then in effect plus a spread which ranges from 65 to 170 basis points or (c) one-month U.S. dollar-LIBOR plus a spread which ranges from 115 to 205 basis points, in each case, depending on the Parent Company’s credit ratings.
Concurrent with the closing of the Term Loan due 2017 in March 2012, the Operating Partnership entered into interest rate swap agreements, which are intended to have the effect of fixing interest payments associated with $200.0 million of the outstanding balance under the Term Loan due 2017 at approximately 2.39% for a five-year term, subject to change depending on the Parent Company’s credit ratings.
Term Loan due 2017 - GBP
On August 2, 2012, the Operating Partnership amended the Term Loan due 2017 agreement to convert approximately $156.4 million of outstanding borrowings of the Term Loan due 2017 into GBP equal to £100.0 million. Borrowings for the GBP-denominated debt under the Term Loan due 2017 bear interest at a floating rate equal to reserve adjusted GBP-LIBOR plus a spread which ranges from 115 to 205 basis points, depending on the Parent Company’s credit ratings.
The Operating Partnership designated the GBP-denominated debt under the Term Loan due 2017 as a net investment hedge. The Operating Partnership intended to hedge the foreign currency exchange risk attributable to changes in the GBP/U.S. dollar exchange rate on a portion of its net investment in its GBP functional currency subsidiary during the period of investment during which the hedging instrument is outstanding. Variability in the GBP/U.S. dollar exchange rate impacts the Operating Partnership as the financial statements of the GBP functional currency subsidiary are translated each period, with the effect of changes in the GBP/U.S. dollar exchange rate being recorded as foreign currency translation gain or loss in other comprehensive income.
Concurrent with the conversion to GBP denominated debt, the Operating Partnership entered into interest rate swap agreements, which are intended to have the effect of fixing interest payments associated with £100.0 million of the outstanding balance under the Term Loan due 2017 at approximately 2.14% for a five-year term of the Term Loan due 2017, subject to change depending on the Parent Company’s credit ratings.
The Term Loan due 2017 includes certain restrictions and covenants which require compliance with financial covenants relating to the minimum amounts of net worth, fixed charge coverage, unsecured debt service coverage, overall leverage and unsecured leverage ratios, the maximum amount of secured indebtedness and certain investment limitations. The Term Loan due 2017 specifies a number of events of default (some of which are subject to applicable cure periods), including, among others, the failure to make payments when due, noncompliance with covenants and defaults under other agreements or instruments of indebtedness. Upon the occurrence of an event of default, the lenders may terminate the Term Loan due 2017 and declare all amounts outstanding to be immediately due and payable.
On September 24, 2013, the Operating Partnership entered into a second amendment to the Term Loan due 2017, which changed, among other things, (1) the definition of “Capitalization Rate” to mean 7.25% with respect to all projects other than the Company's Center for Life Science | Boston property, and 6.25% with respect to the Center for Life Science | Boston property and (2) certain definitions used to calculate the financial covenants.
Management believes that the Operating Partnership was in compliance with the covenants as of December 31, 2014.
Unsecured Line of Credit and Term Loan due 2018
On July 14, 2011, the Operating Partnership entered into an unsecured credit agreement with KeyBank, as administrative agent and co-lead arranger, Wells Fargo Securities, LLC as co-lead arranger, and certain other lenders. The unsecured credit agreement provided for available borrowings under a revolving line of credit of $750.0 million with a maturity date of March 24, 2018.
On September 24, 2013, the Operating Partnership entered into an amended and restated unsecured credit agreement (the “Amended and Restated Credit Facility”), amending and restating its unsecured credit agreement dated July 14, 2011, as amended. The Amended and Restated Credit Facility provides for aggregate borrowings of up to $1.25 billion, consisting of a $900.0 million revolving line of credit and a $350.0 million Term Loan due 2018, with a maturity date of March 24, 2018. Subject to the administrative agent’s reasonable discretion, the Operating Partnership may increase the amount of the commitments under the Amended and Restated Credit Facility up to $1.8 billion upon satisfying certain conditions. In addition, the Operating Partnership, at its sole discretion, may extend the maturity date to September 24, 2018 after satisfying certain conditions and paying an extension fee. Borrowings under the unsecured line of credit and the Term Loan due 2018 are guaranteed by the Parent Company. In connection with the Amended and Restated Credit Facility, unamortized loan fees under the previous credit agreement of approximately $462,500 were charged to interest expense.
Borrowings under the Amended and Restated Credit Facility bear interest at floating rates equal to, at the Operating Partnership’s option, either (1) reserve-adjusted LIBOR plus a spread which ranges from 92.5 to 170 basis points (with respect to the unsecured line of credit) and a spread which ranges from 95 to 195 basis points (with respect to the Term Loan due 2018), in each case depending on the Parent Company’s credit ratings, or (2) the highest of (a) the prime rate then in effect plus a spread which ranges from 0 to 70 basis points, (b) the federal funds rate then in effect plus a spread which ranges from 50 to 120 basis points, or (c) one-month LIBOR plus a spread which ranges from 92.5 to 170 basis points (with respect to the unsecured line of credit) and a spread which ranges from 95 to 195 basis points (with respect to the Term Loan due 2018), in each case depending on the Parent Company’s credit ratings. In addition, a facility fee is payable on the total $900.0 million capacity of the unsecured line of credit, which ranges from 12.5 to 30 basis points per annum, depending on the Parent Company’s credit ratings.
The Amended and Restated Credit Facility includes certain restrictions and covenants which require compliance with financial covenants relating to the minimum amounts of net worth, fixed charge coverage, unsecured debt service coverage, overall leverage and unsecured leverage ratios, the maximum amount of secured indebtedness and certain investment limitations. The unsecured credit agreement specifies a number of events of default (some of which are subject to applicable cure periods), including, among others, the failure to make payments when due, noncompliance with covenants and defaults under other agreements or instruments of indebtedness. Upon the occurrence of an event of default, the lenders may terminate the revolving line of credit and declare all amounts outstanding to be immediately due and payable. Management believes that the Operating Partnership was in compliance with these covenants as of December 31, 2014.
On September 25, 2013, the Operating Partnership entered into interest rate swap agreements, which are intended to have the effect of fixing interest payments associated with $200.0 million of the Term Loan due 2018 outstanding at approximately 2.1% for a three-year term, subject to adjustment based on the Parent Company's credit ratings. See Note 9 for further details.
Net Investment Hedge
The Operating Partnership designated the GBP denominated debt under the Term Loan due 2017 as a net investment hedge. The Operating Partnership entered into this net investment hedge to protect a designated amount of the Operating Partnership’s net investment in a GBP functional currency subsidiary against the risk of adverse changes in the GBP/U.S. dollar exchange rate (foreign exchange risk). Variability in the GBP/U.S. dollar exchange rate impacts the Operating Partnership (a U.S. dollar functional currency entity) as the financial statements of the GBP functional currency subsidiary are translated each period, with the effect of changes in the GBP/U.S. dollar exchange rate being recorded in accumulated other comprehensive income. When the net investment is sold or substantially liquidated, the balance of the translation adjustment accumulated in other comprehensive income will be reclassified into earnings. The Operating Partnership is hedging the risk of changes in the U.S. dollar equivalent value of a portion of its net investment in its GBP subsidiary attributable to changes in the GBP/U.S. dollar exchange rate during the period of investment during which the hedging instrument is outstanding.
Maturities of Long-Term Debt
As of December 31, 2014, principal payments due for the Operating Partnership’s consolidated indebtedness (excluding debt premiums and discounts) were as follows (in thousands):
2015 (1)	$	127,320
2016	650,618
2017	431,632
2018	481,804
2019	405,724
Thereafter	615,802
	$	2,712,900
-1	Includes $95.7 million in principal payments of the Exchangeable Senior Notes based on the Company's previously announced redemption date of January 30, 2015, which subsequent to December 31, 2014, were exchanged in full for 5,764,026 shares of the Parent Company's common stock at the request of the holders.

Earnings_Per_Share_of_the_Pare

Earnings Per Share of the Parent Company	12 Months Ended
	Dec. 31, 2014
Earnings Per Share, Basic and Diluted [Abstract]
Earnings Per Share of the Parent Company	Earnings Per Share of the Parent Company
	Grants of restricted stock of the Parent Company and LTIP units of the Operating Partnership in share-based payment transactions are considered participating securities prior to vesting and, therefore, are considered in computing basic earnings per share under the two-class method. The two-class method is an earnings allocation method for calculating earnings per share when a company’s capital structure includes either two or more classes of common stock or common stock and participating securities. Basic earnings per share under the two-class method is calculated based on dividends declared on common shares and other participating securities (“distributed earnings”) and the rights of participating securities in any undistributed earnings, which represents net income remaining after deduction of dividends accruing during the period. The undistributed earnings are allocated to all outstanding common shares and participating securities based on the relative percentage of each security to the total number of outstanding participating securities. Basic earnings per share represents the summation of the distributed and undistributed earnings per share class divided by the total number of shares.
	Through December 31, 2014 all of the Company’s participating securities (including the OP units) received dividends/distributions at an equal dividend/distribution rate per share/unit. As a result, the portion of net income allocable to the weighted-average unvested restricted stock outstanding for the years ended December 31, 2014, 2013 and 2012 has been deducted from net income available to common stockholders to calculate basic earnings per share. The calculation of diluted earnings per share for the years ended December 31, 2014, 2013 and 2012 includes the outstanding OP units (both vested and unvested) in the weighted-average shares, and net income attributable to noncontrolling interests in the Operating Partnership has been added back to net income available to common stockholders. For the years ended December 31, 2014 and 2013, the Performance Units were dilutive to the calculation of diluted earnings per share as calculated, assuming that December 31, 2014 and December 31, 2013 was the end date of the respective Performance Units' Performance Period. For the year ended December 31, 2012, the Performance Units were anti-dilutive to the calculation of diluted earnings per share as calculated, assuming that December 31, 2012 was the end date of the Performance Units' Performance Period. For the years ended December 31, 2014, 2013 and 2012, the unvested restricted stock was anti-dilutive to the calculation of diluted earnings per share and was therefore excluded. As a result, diluted earnings per share was calculated based upon net income available to common stockholders less net income allocable to unvested restricted stock and distributions in excess of earnings attributable to unvested restricted stock. In addition, for the year ended December 31, 2014, 8,631,164 shares issuable upon settlement of the exchange feature of the Exchangeable Senior Notes were dilutive and were included in the calculation of diluted earnings per share based on the “if converted” method. For the years ended December 31, 2013 and 2012, 10,405,224 and 10,259,496 shares issuable upon settlement of the exchange feature of the Exchangeable Senior Notes were anti-dilutive and were not included in the calculation of diluted earnings per share based on the “if converted” method , respectively. No other shares were considered anti-dilutive for the years ended December 31, 2014, 2013 and 2012.
	Computations of basic and diluted earnings per share (in thousands, except share data) were as follows:
		Years Ended December 31,
		2014			2013			2012
	Basic earnings per share:
	Income from continuing operations	$	201,468		$	47,209		$	16,133
	Income from continuing operations attributable to noncontrolling interests	(7,690		)	(565		)	(20		)
	Preferred stock dividends	—			(2,393		)	(14,603		)
	Cost on redemption of preferred stock	—			(6,531		)	—
	Net income allocable and distributions in excess of earnings to participating securities (continuing operations)	(1,954		)	(1,350		)	(1,300		)
	Income from continuing operations available to common stockholders - basic	191,824			36,370			210
	Loss from discontinued operations	—			—			(4,370		)
	Loss from discontinued operations attributable to noncontrolling interests	—			—			82
	Loss from discontinued operations available to common stockholders - basic	—			—			(4,288		)
	Net income / (loss) available to common stockholders - basic	$	191,824		$	36,370		$	(4,078	)
	Diluted earnings per share:
	Income from continuing operations available to common stockholders - basic	191,824			36,370			210
	Income from continuing operations attributable to noncontrolling interests in Operating Partnership	5,246			819			29
	Interest expense on Exchangeable Senior Notes	5,533			—			—
	Income from continuing operations available to common stockholders - diluted	202,603			37,189			239
	Loss from discontinued operations available to common stockholders - basic and diluted	—			—			(4,288		)
	Loss from discontinued operations attributable to noncontrolling interests in the Operating Partnership	—			—			(82		)
	Loss from discontinued operations available to common stockholders - basic and diluted	—			—			(4,370		)
	Net income / (loss) available to common stockholders - diluted	$	202,603		$	37,189		$	(4,131	)
	Weighted-average common shares outstanding:
	Basic	193,003,934			182,043,391			152,752,086
	Incremental shares from assumed conversion:
	Performance units	191,180			63,017			—
	Operating partnership and LTIP units	5,406,682			4,290,614			2,948,301
	Shares issuable upon settlement of the exchange feature of the Exchangeable Senior Notes	8,631,164			—			—
	Diluted	207,232,960			186,397,022			155,700,387
	Basic and diluted earnings per share:
	Income from continuing operations per share available to common stockholders - basic	$	0.99		$	0.2		$	—
	Income from continuing operations per share available to common stockholders - diluted	$	0.98		$	0.2		$	—
	Loss from discontinued operations per share available to common stockholders - basic and diluted	$	—		$	—		$	(0.03	)
	Net income / (loss) per share available to common stockholders - basic	$	0.99		$	0.2		$	(0.03	)
	Net income / (loss) per share available to common stockholders - diluted	$	0.98		$	0.2		$	(0.03	)

Earnings_Per_Unit_of_the_Opera

Earnings Per Unit of the Operating Partnership	12 Months Ended
	Dec. 31, 2014
Partnership Income [Abstract]
Earnings Per Unit of the Operating Partnership	Earnings Per Unit of the Operating Partnership
	Restricted units granted in equity-based payment transactions are considered participating securities prior to vesting and, therefore, are considered in computing basic earnings per unit under the two-class method. The two-class method is an earnings allocation method for calculating earnings per unit when a company’s capital structure includes either two or more classes of common equity or common equity and participating securities. Basic earnings per unit under the two-class method is calculated based on distributions declared on the OP units and other participating securities (“distributed earnings”) and the rights of participating securities in any undistributed earnings, which represents net income remaining after deduction of distributions accruing during the period. The undistributed earnings are allocated to all outstanding OP units and participating securities based on the relative percentage of each security to the total number of outstanding participating securities. Basic earnings per unit represents the summation of the distributed and undistributed earnings per unit class divided by the total number of OP units.
	Through December 31, 2014, all of the Operating Partnership’s participating securities received distributions at an equal distribution rate per unit. As a result, the portion of net income allocable to the weighted-average unvested OP units outstanding for the years ended December 31, 2014, 2013 and 2012 has been deducted from net income available to unit holders to calculate basic earnings per unit. For the years ended December 31, 2014, 2013 and 2012, the unvested OP units were anti-dilutive to the calculation of earnings per unit and were therefore excluded from the calculation of diluted earnings per unit, and diluted earnings per unit is calculated based upon net income attributable to unit holders. For the years ended December 31, 2014 and 2013, the Performance Units were dilutive to the calculation of diluted earnings per unit as calculated, assuming that December 31, 2014 and 2013 was the end date of the respective Performance Units’ Performance Period. For the year ended December 31, 2012, the Performance Units were anti-dilutive to the calculation of diluted earnings per unit as calculated, assuming that December 31, 2012 was the end date of the Performance Units' Performance Period. In addition, for the year ended December 31, 2014, 8,631,164 units issuable upon settlement of the exchange feature of the Exchangeable Senior Notes were dilutive and were included in the calculation of diluted earnings per unit based on the “if converted” method. For the years ended December 31, 2013 and 2012, 10,405,224 and 10,259,496 units issuable upon settlement of the exchange feature of the Exchangeable Senior Notes were anti-dilutive and were not included in the calculation of diluted earnings per unit based on the “if converted” method, respectively. No other units were considered anti-dilutive for the years ended December 31, 2014, 2013 or 2012.
	Computations of basic and diluted earnings per unit (in thousands, except unit data) were as follows:
		Years Ended December 31,
		2014			2013			2012
	Basic earnings per unit:
	Income from continuing operations	$	201,468		$	47,209		$	16,133
	(Income) / Loss from continuing operations attributable to noncontrolling interests	(2,444		)	254			8
	Preferred unit distributions	—			(2,393		)	(14,603		)
	Cost on redemption of preferred units	—			(6,531		)	—
	Net income allocable and distributions in excess of earnings to participating securities (continuing operations)	(1,954		)	(1,354		)	(1,326		)
	Income from continuing operations available to unit holders - basic	197,070			37,185			212
	Loss from discontinued operations - basic	—			—			(4,370		)
	Net income / (loss) available to unit holders - basic	$	197,070		$	37,185		$	(4,158	)
	Diluted earnings per unit
	Income from continuing operations available to unit holders - basic	197,070			37,185			212
	Interest expense on Exchangeable Senior Notes	5,533			—			—
	Income from continuing operations available to unit holders - diluted	202,603			37,185			212
	Loss from discontinued operations available to unit holders - diluted	—			—			(4,370		)
	Net income / (loss) available to common unit holders - diluted	202,603			37,185			(4,158		)
	Weighted-average units outstanding:
	Basic	198,410,616			186,333,292			155,670,931
	Incremental units from assumed conversion:
	Performance units	191,180			63,017			—
	Units issuable upon settlement of the exchange feature of the Exchangeable Senior Notes	8,631,164			—			—
	Diluted	207,232,960			186,396,309			155,670,931
	Basic and diluted earnings per unit:
	Income from continuing operations per unit available to unit holders - basic	$	0.99		$	0.2		$	—
	Income from continuing operations per unit available to unit holders - diluted	$	0.98		$	0.2		$	—
	Loss from discontinued operations per share available to unit holders - basic and diluted	$	—		$	—		$	(0.03	)
	Net income / (loss) per unit available to unit holders - basic	$	0.99		$	0.2		$	(0.03	)
	Net income / (loss) per unit available to unit holders - diluted	$	0.98		$	0.2		$	(0.03	)

Investment_in_Unconsolidated_P

Investment in Unconsolidated Partnerships	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Investment in Unconsolidated Partnerships	Investment in Unconsolidated Partnerships
	The accompanying consolidated financial statements include investments in two limited liability companies with Prudential Real Estate Investors (“PREI”), 10165 McKellar Court, L.P. (“McKellar Court”), a limited partnership with Quidel Corporation, the tenant which occupies the McKellar Court property and BioPark Fremont, LLC ("BioPark Fremont"), a limited liability company with RPC Poppleton, LLC. General information on the PREI limited liability companies, the McKellar Court partnership and BioPark Fremont (each referred to in this footnote individually as a “partnership” and collectively as the “partnerships”) as of December 31, 2014 was as follows:
	Name	Partner		Company’s		Company’s		Date Acquired
				Ownership		Economic
				Interest		Interest
	PREI I LLC (1)	PREI		20%		20%		April 4, 2007
	PREI II LLC	PREI		20%		20%		April 4, 2007
	McKellar Court (2)	Quidel Corporation		22%		22%		September 30, 2004
	BioPark Fremont	RPC Poppleton, LLC		50%		50%		May 31, 2013
	-1	PREI I LLC owns two properties in Cambridge, Massachusetts. At December 31, 2014, there were $139.0 million in outstanding borrowings on a secured loan facility held by a wholly-owned subsidiary of PREI I LLC, with a contractual interest rate of 2.21% (including the applicable credit spread) and a maturity date of August 13, 2015 (with an option to extend the maturity date to August 13, 2016 at its discretion after satisfying certain conditions and paying an extension fee).
	-2	The Company’s investment in the McKellar Court partnership (maximum exposure to losses) was approximately $11.8 million at December 31, 2014. The Company’s economic interest in the McKellar Court partnership entitles it to 75% of the extraordinary cash flows after repayment of the partners’ capital contributions and 22% of the operating cash flows.
	The condensed combined balance sheets for all of the Company’s unconsolidated partnerships were as follows (in thousands):
		December 31,				December 31,
		2014				2013
	Assets:
	Investments in real estate, net	$	267,007			$	262,753
	Cash and cash equivalents (including restricted cash)	6,057				3,855
	Other assets	11,599				5,301
	Total assets	$	284,663			$	271,909
	Liabilities and members’ equity:
	Mortgage notes payable and secured loan	$	152,056			$	151,968
	Other liabilities	9,020				12,102
	Members’ equity	123,587				107,839
	Total liabilities and members equity	$	284,663			$	271,909
	Company’s net investment in unconsolidated partnerships	$	35,291			$	32,137
	The selected data and results of operations for the unconsolidated partnerships were as follows (in thousands):
			Years Ended December 31,
			2014				2013			2012
	Total revenues		$	35,495			$	12,930		$	8,823
	Total expenses		(36,013		)		(21,589		)	(19,939		)
	Net loss		$	(518	)		$	(8,659	)	$	(11,116	)
	Company’s equity in net income / (loss) of unconsolidated partnerships		$	745			$	(905	)	$	(1,389	)
	Fees earned by the Company (1)		$	999			$	260		$	90
	-1	The Company acts as the operating member or partner, as applicable, and day-to-day manager for the partnerships. The Company is entitled to receive fees for providing construction and development services (as applicable) and management services to the PREI joint ventures, which are reflected in tenant recoveries and other income in the consolidated statements of operations.

Derivatives_and_Other_Financia

Derivatives and Other Financial Instruments	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Other Financial Instruments	Derivatives and Other Financial Instruments
	The Company is exposed to the effect of changes in interest rates on the Operating Partnership’s U.S. dollar-LIBOR-based and GBP-LIBOR-based debt. The Company limits this risk by following established risk management policies and procedures including the use of derivatives. The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements related to the Operating Partnership’s LIBOR-based debt. To accomplish these objectives, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. The interest rate swaps hedge the Company’s exposure to the variability on expected cash flows attributable to changes in interest rates. These interest rate swaps are currently intended to hedge interest payments associated with the Operating Partnership’s Term Loan due 2017 and Term Loan due 2018.
	On March 30, 2012, the Company entered into four interest rate swaps with an aggregate notional amount of $200 million under which at each monthly settlement date the Company either (1) receives the difference between a fixed interest rate (the “USD Strike Rate”) and one-month U.S. dollar-LIBOR if the USD Strike Rate is less than one-month U.S. dollar-LIBOR or (2) pays such difference if the USD Strike Rate is greater than one-month U.S. dollar-LIBOR. The interest rate swaps hedge the Company’s exposure to the variability on expected cash flows attributable to changes in interest rates on the first interest payments, due on the date that is on or closest after each swap’s settlement date, associated with the amount of one-month U.S. dollar-LIBOR-based debt equal to each swap’s notional amount. These interest rate swaps, with a notional amount of $200 million are currently intended to hedge interest payments associated with the Operating Partnership’s Term Loan due 2017 - U.S. Dollar. No initial investment was made to enter into the interest rate swap agreements.
	On August 2, 2012, in connection with the conversion of a portion of the outstanding borrowings under the Term Loan due 2017 into GBP (for further discussion, see Note 5 above), the Company entered into two interest rate swaps with an aggregate notional amount of £100 million under which at each monthly settlement date the Company either (1) receives the difference between a fixed interest rate (the “GBP Strike Rate”) and one-month GBP-LIBOR if the GBP Strike Rate is less than one-month GBP-LIBOR or (2) pays such difference if the GBP Strike Rate is greater than one-month GBP-LIBOR. The interest rate swaps hedge the Company’s exposure to the variability on expected cash flows attributable to changes in interest rates on the first interest payments, due on the date that is on or closest after each swap’s settlement date, associated with the amount of one-month GBP-LIBOR-based debt equal to each swap’s notional amount. These interest rate swaps, with a notional amount of £100 million, are currently intended to hedge interest payments associated with the Operating Partnership’s Term Loan due 2017 - GBP. No initial investment was made to enter into the interest rate swap agreements.
	On September 25, 2013, the Operating Partnership entered into three interest rate swaps with an aggregate notional amount of $200.0 million under which at each monthly settlement date the Company either (1) receives the difference between a fixed interest rate (the “Strike Rate”) and one-month U.S. dollar-LIBOR if the Strike Rate is less than one-month U.S. dollar-LIBOR or (2) pays such difference if the Strike Rate is greater than one-month U.S. dollar-LIBOR. The interest rate swaps hedge the Company’s exposure to the variability on expected cash flows attributable to changes in interest rates on the first interest payment, due date on or after each swap’s settlement date, associated with the amount of one-month U.S. dollar-LIBOR-based debt equal to each swap’s notional amount. These interest rate swaps, with a notional amount of $200.0 million, are currently intended to hedge interest payments associated with the Operating Partnership’s Term Loan due 2018 for three years. No initial investment was made to enter into the interest rate swap agreements.
	As of December 31, 2014, the Company had deferred interest costs of approximately $28.6 million in accumulated other comprehensive loss related to forward starting swaps, which were settled with the corresponding counterparties in 2009. The forward starting swaps were entered into to mitigate the Company’s exposure to the variability in expected future cash flows attributable to changes in future interest rates associated with a forecasted issuance of fixed-rate debt, with interest payments for a minimum of ten years. The deferred interest costs will be amortized as additional interest expense over a remaining period of approximately four years.
	The following is a summary of the terms of the interest rate swaps and their respective fair-values (dollars in thousands):
												Fair-Value(1)
		Notional Amount										December 31,			December 31,
						Strike Rate			Effective Date	Expiration Date		2014			2013
	Interest rate swaps	$	200,000			1.163	%		March 30, 2012	March 30, 2017		$	(1,448	)	$	(1,876	)
	Interest rate swaps	200,000				0.701	%		October 1, 2013	October 1, 2016		(186		)	(288		)
	Interest rate swaps(2)	77,865				0.731	%		August 2, 2012	March 30, 2017		63			1,545
	Interest rate swaps(2)	77,865				0.7425	%		August 2, 2012	March 30, 2017		45			1,519
	Total interest rate swaps	$	555,730									$	(1,526	)	$	900
	-1	Fair-value of derivative instruments does not include any related accrued interest payable, which is included in accrued expenses on the accompanying consolidated balance sheets. Derivative valuations are classified in Level 2 of the fair-value hierarchy. Assets are included in other assets and liabilities are included in accounts payable, accrued expenses and other liabilities on the accompanying consolidated balance sheets.
	-2	Translation to U.S. dollars is based on exchange rates of $1.56 to £1.00 and $1.65 to £1.00 at December 31, 2014 and December 31, 2013, respectively.
	For derivatives designated as cash flow hedges, the effective portion of changes in the fair-value of the derivative is initially reported in other comprehensive income (outside of earnings) and subsequently reclassified to earnings in the period in which the hedged forecasted transaction affects earnings. During the years ended December 31, 2014, 2013 and 2012, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt. The ineffective portion of the change in fair-value of the derivatives is recognized directly in earnings. No portion of the derivatives designated as cash flow hedges were classified as ineffective during the years ended December 31, 2014, 2013 or 2012.
	During the year ended December 31, 2013, the Company recorded a total gain on derivative instruments of $416,000, primarily related to changes in the fair-value of other derivative instruments, which were included in other income within the consolidated statement of operations.
	Amounts reported in accumulated other comprehensive loss related to derivatives will be reclassified to earnings during the period in which the hedged forecasted transaction affects earnings. The change in net unrealized gain / (loss) on derivative instruments includes reclassifications of net unrealized losses from accumulated other comprehensive loss as (1) an increase to interest expense of $10.3 million, $9.5 million and $8.5 million for the years ended December 31, 2014, 2013 and 2012, respectively, and (2) a (loss) / gain on derivative instruments of $(23,000), $416,000 and $(9,000) for the years ended December 31, 2014, 2013 and 2012, respectively. During the next twelve months, the Company estimates that an additional $9.4 million will be reclassified from accumulated other comprehensive loss as an increase to interest expense. In addition, for the years ended December 31, 2014, 2013 and 2012, approximately $922,000, $326,000 and $118,000, respectively, of settlement payments on interest rate swaps have been deferred in accumulated other comprehensive loss and will be amortized over the useful lives of the related development or redevelopment projects.
	The following is a summary of the amount of gain / (loss) recognized in other comprehensive income related to the derivative instruments (in thousands):
			Year Ended
			December 31,
			2014				2013			2012
	Amount of (loss) / gain recognized in other comprehensive income (effective portion):
	Cash flow hedges
	Interest rate swaps		$	(6,625	)		$	3,497		$	(6,863	)
	Amount of loss reclassified from accumulated other comprehensive loss to income (effective portion):
	Cash flow hedges
	Interest rate swaps (1)		$	(3,537	)		$	(2,619	)	$	(1,578	)
	Forward starting swaps (2)		(6,722		)		(6,832		)	(6,933		)
	Total interest rate swaps		$	(10,259	)		$	(9,451	)	$	(8,511	)
	Amount of (loss) / gain recognized in income (ineffective portion and amount excluded from effectiveness testing):
	Other derivative instruments		(23		)		416			(9		)
	Total (loss) / gain on derivative instruments		$	(23	)		$	416		$	(9	)
	-1	Amount represents payments made to swap counterparties for the effective portion of interest rate swaps that were recognized as an increase to interest expense for the periods presented (the amount was recorded as an increase and corresponding decrease to accumulated other comprehensive loss in the same accounting period).
	-2	Amount represents reclassifications of deferred interest costs from accumulated other comprehensive loss to interest expense related to the Company’s previously settled forward starting swaps.

FairValue_of_Financial_Instrum

Fair-Value of Financial Instruments	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Disclosures	Fair-Value of Financial Instruments
	The Company’s disclosures of estimated fair-value of financial instruments at December 31, 2014 and December 31, 2013 were determined using available market information and appropriate valuation methods. Considerable judgment is necessary to interpret market data and develop estimated fair-value. The use of different market assumptions or estimation methods may have a material effect on the estimated fair-value amounts.
	The carrying amounts for cash and cash equivalents, accounts receivable, accounts payable, accrued expenses and other liabilities approximate fair-value due to the short-term nature of these instruments.
	The Company utilizes quoted market prices to estimate the fair-value of its fixed-rate and variable-rate debt, when available. If quoted market prices are not available, the Company calculates the fair-value of its mortgage notes payable and other fixed-rate debt based on a currently available market rate assuming the loans are outstanding through maturity and considering the collateral. In determining the current market rate for fixed-rate debt, a market credit spread is added to the quoted yields on federal government treasury securities with similar terms to debt. In determining the current market rate for variable-rate debt, a market credit spread is added to the current effective interest rate. The carrying values of interest rate swaps are reflected at their fair-values.
	At December 31, 2014 and December 31, 2013, the aggregate fair-value and the carrying value of the Company’s financial instruments were as follows (in thousands):
		December 31, 2014				December 31, 2013
		Fair-Value (1)		Carrying Value		Fair-Value (1)			Carrying Value
	Mortgage notes payable, net	$	502,115	$	496,757	$	730,394		$	709,324
	Exchangeable Senior Notes	134,619		95,678		202,626			180,000
	Notes due 2016, net	411,600		399,304		417,040			398,787
	Noted due 2019, net	398,280		397,873		—			—
	Notes due 2020, net	283,250		248,450		275,600			248,210
	Notes due 2022, net	258,250		248,275		240,400			248,086
	Term Loan due 2017 - U.S. dollar	244,945		243,596		244,751			243,596
	Term Loan due 2017 - GBP (2)	156,589		155,730		165,969			165,190
	Term Loan due 2018	350,557		350,000		350,000			350,000
	Unsecured line of credit	83,866		84,000		128,000			128,000
	Derivative instruments (3)	1,132		1,132		(1,316		)	(1,316		)
	Available-for-sale securities	58,621		58,621		19,566			19,566
	-1	Fair-values of debt and derivative instruments are classified in Level 2 of the fair-value hierarchy. Fair-value of available-for-sale securities are classified in Level 1 of the fair-value hierarchy.
	-2	The principal balance represents the U.S. dollar amount based on the exchange rate of $1.56 to £1.00 and $1.65 to £1.00 at December 31, 2014 and December 31, 2013, respectively.
	-3	The Company’s derivative instruments are reflected in other assets and in accounts payable, accrued expenses and other liabilities on the accompanying consolidated balance sheets based on their respective balances (see Note 9).

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Business Combination Disclosure	Acquisitions
	The Company acquired the following properties during the year ended December 31, 2014. The table below reflects the preliminary purchase price allocation for these acquisitions (in thousands).
	Property		Acquisition Date	Investments in Real Estate		Above Market Lease		Below Market Lease			Below Market Ground Lease		In-Place Lease		Debt Premium			Acquisition Date Fair-Value
	100 College Street (1)		April 4, 2014	$	63,361	$	—	$	—		$	—	$	33,239	$	—		$	96,600
	300 George Street (2)		April 4, 2014	107,021		63		(3,926		)	—		17,808		(3,966		)	117,000
	430 Cambridge Science Park (3)		May 15, 2014	—		—		—			3,836		—		—			3,836
	Wake 60 (4)		December 17, 2014	3,525		—		—			—		—		—			3,525
	Total			$	173,907	$	63	$	(3,926	)	$	3,836	$	51,047	$	(3,966	)	$220,961
	Weighted average intangible amortization life (in months)					21		143			1500		159		135
	-1	The property is currently under construction in New Haven Connecticut and is expected to be a 510,419 square foot laboratory and office building. The total project investment was estimated to be approximately $191 million at acquisition, comprised of (a) approximately $89 million in cash, assumption of mortgage notes payable and a noncontrolling interest of Winstanley Enterprises LLC and affiliates, which will also continue to provide construction and property management services for the property, and (b) approximately $102 million of estimated remaining construction costs from the date of acquisition. As of April 4, 2014, Winstanley Enterprises, LLC and affiliates retained an approximate 25% noncontrolling interest. On June 3, 2014, Winstanley Enterprises LLC and its affiliates' noncontrolling interest was reduced to approximately 7% as a result of additional investments by the Company. Upon completion of construction and repayment of the related construction loan, the Company expects Winstanley Enterprises LLC and its affiliates' noncontrolling interest in the property to be reduced to approximately 2.5%.
	-2	The property is a 518,940 square foot laboratory and office building in New Haven, Connecticut. The total consideration also included the assumption of $46.3 million of mortgage notes payable and a 7% noncontrolling interest of Winstanley Enterprises LLC, which will also continue to provide property management services for the property.
	-3	The property is currently under construction in Cambridge, United Kingdom and is expected to be a 42,410 square foot laboratory and office building. The total project investment at acquisition was expected to be approximately $22.7 million

Discontinued_Operations

Discontinued Operations	12 Months Ended
	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations
	In April 2012, the Company completed the exchange of an operating property on Forbes Boulevard in South San Francisco for an office property located in Redwood City, California. As a result, during the year ended December 31, 2012, the Company reclassified the Forbes Boulevard property as a discontinued operation. The table below reflects the details of the property and the exchange (in thousands):
	Property		Date of Sale		Original Acquisition Date	Sales Price (1)		Impairment loss
	Forbes Boulevard		April 27, 2012		September 5, 2007	$	28,000	$	(4,552	)
	-1	The sales price was equal to the fair-value of the office property received as consideration in the exchange with the independent third party.
	The results of operations of the Forbes Boulevard property are reported as discontinued operations for all periods presented in the accompanying consolidated financial statements. The following table summarizes the revenue and expense components that comprise income / (loss) from discontinued operations (in thousands):
			Year Ended December 31, 2012
	Total revenues		$	454
	Total expenses		272
	Income from discontinued operations before impairment loss		182
	Impairment loss		(4,552		)
	Loss from discontinued operations		$	(4,370	)
	Discontinued operations have not been segregated in the consolidated statements of cash flows. Therefore, amounts for certain captions will not agree with respective data in the consolidated statements of operations.

Incentive_Award_Plan_Incentive

Incentive Award Plan Incentive Award Plan	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	Selected data of the Company’s incentive award plan is presented below (in thousands, except share and period amounts):
		Years Ended December 31,
		2014			2013		2012
	Aggregate value of restricted stock/LTIP Units granted	$	11,181		$	13,234	$	7,300
	Aggregate value of Performance Units granted	$	4,186		$	4,973	$	3,329
	Fair-value of stock/LTIP Units vested	$	11,782		$	13,321	$	9,502
	Stock-based compensation expense recognized in general and administrative expenses and rental operations expense - restricted stock/LTIP Units	$	12,188		$	10,134	$	9,556
	Stock-based compensation expense recognized in general and administrative expenses - Performance Units	$	3,574		$	2,445	$	1,974
	Shares surrendered to the Company and retired in lieu of cash payments for taxes due on the vesting of restricted stock	225,906			253,671		178,915
	Data at period end:
	Total compensation to be expensed related to unvested awards in future periods - restricted stock	$	16,926
	Weighted-average expense period (in years) - restricted stock	2.4
	Total compensation to be expensed related to unvested awards in future periods - Performance Units	$	3,179
	Weighted-average expense period (in years) - Performance Units	1.8
Incentive Award Plan Selected Data [Table Text Block]	Incentive Award Plan
	The Company has adopted the 2013 Amendment and Restatement of the BioMed Realty Trust, Inc. and BioMed Realty, L.P. 2004 Incentive Award Plan (the “Plan”). The Plan provides for grants to directors, employees and consultants of the Company and the Operating Partnership (and their respective subsidiaries) of stock options, restricted stock, LTIP units, stock appreciation rights, dividend equivalents, and other incentive awards. The Company has reserved 10,740,000 shares of common stock for issuance pursuant to the Plan, subject to adjustments as set forth in the Plan. As of December 31, 2014, 6,534,731 shares of common stock or awards convertible into or exchangeable for common stock remained available for future issuance under the Plan. Each LTIP unit and each Performance Unit issued will count as one share of common stock for purposes of calculating the limit on shares that may be issued. Compensation cost for these incentive awards is measured based on the fair-value of the award on the grant date (fair-value is calculated based on the closing price of the Company’s common stock on the date of grant) and is recognized as expense over the respective vesting period, which for restricted stock awards and LTIP units is generally four to five years. Fully vested incentive awards may be settled for either cash or stock depending on the Company’s election and the type of award granted. Participants are entitled to cash dividends and may vote such awarded shares, but the sale or transfer of such shares is limited during the restricted or vesting period. The restricted stock grants may only be settled for stock whereas the LTIP units may be redeemed for either cash or common stock, at the Company’s election.
	The Parent Company has awarded Performance Units to certain of its executive officers, which represent the maximum number of Performance Units that may vest. Each Performance Unit represents a contingent right to receive one share of the Parent Company’s common stock if vesting conditions are satisfied. Performance Units vest at the end of designated time periods (each, a “Performance Period”) based upon the Parent Company’s total stockholder return relative to its peer group (the “Market Conditions”). The grant date fair-value of the Performance Units was estimated using a Monte Carlo simulation which considered the likelihood of achieving the Market Conditions. The Monte Carlo simulation uses a statistical formula underlying the Black-Scholes and binomial formulas, and such simulation was run approximately 100,000 times. For each simulation, the value of the payoff was calculated at the end of the respective Performance Period and was then discounted to the grant date at a risk-free interest rate. The expected value of the Performance Units on the grant date was determined by simulating the total shareholder return for the Company and the peer group considering the stock price variance for each of the peer group companies, compared to each other and the Company's stock estimating the rank of the Company's stock. The valuation was performed in a risk-neutral framework, so no assumption was made with respect to an equity risk premium. Other significant assumptions used in the valuation included an expected term of 24 and 36 months, an average risk-free interest rate of 0.49%, and an average dividend yield of 4.64%. No dividends will be paid or accrued on the Performance Units, and shares of the Parent Company’s common stock will not be issued until vesting of the Performance Units occurs.
	A summary of the Company’s unvested restricted stock and LTIP units is presented below:
		Unvested Restricted Shares/LTIP Units		Weighted Average Grant-Date Fair-Value
	Balance at December 31, 2011	1,721,062		$	16.09
	Granted	395,350		18.46
	Vested	(520,258	)	15.17
	Forfeited	(35,642	)	15.97
	Balance at December 31, 2012	1,560,512		17
	Granted	657,106		20.33
	Vested	(665,808	)	15.91
	Forfeited	(39,805	)	18.15
	Balance at December 31, 2013	1,512,005		18.91
	Granted	587,662		18.94
	Vested	(602,228	)	18.18
	Forfeited	(20,427	)	19.83
	Balance at December 31, 2014	1,477,012		$	19.1
	Selected data of the Company’s incentive award plan is presented below (in thousands, except share and period amounts):
		Years Ended December 31,
		2014			2013		2012
	Aggregate value of restricted stock/LTIP Units granted	$	11,181		$	13,234	$	7,300
	Aggregate value of Performance Units granted	$	4,186		$	4,973	$	3,329
	Fair-value of stock/LTIP Units vested	$	11,782		$	13,321	$	9,502
	Stock-based compensation expense recognized in general and administrative expenses and rental operations expense - restricted stock/LTIP Units	$	12,188		$	10,134	$	9,556
	Stock-based compensation expense recognized in general and administrative expenses - Performance Units	$	3,574		$	2,445	$	1,974
	Shares surrendered to the Company and retired in lieu of cash payments for taxes due on the vesting of restricted stock	225,906			253,671		178,915
	Data at period end:
	Total compensation to be expensed related to unvested awards in future periods - restricted stock	$	16,926
	Weighted-average expense period (in years) - restricted stock	2.4
	Total compensation to be expensed related to unvested awards in future periods - Performance Units	$	3,179
	Weighted-average expense period (in years) - Performance Units	1.8

Commitments_and_Contingencies_

Commitments and Contingencies Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	Commitments and Contingencies
	Concentration of Credit Risk
	Life science entities comprise the vast majority of the Company’s tenant base. Because of the dependence on a single industry, adverse conditions affecting that industry will more adversely affect our business. Two of the Company’s tenants, Human Genome Sciences, Inc., a wholly owned subsidiary of GlaxoSmithKline plc, and Vertex Pharmaceuticals Incorporated, comprised 9.6% and 7.2%, or $46.5 million and $34.9 million, respectively, of rental revenues for the year ended December 31, 2014; 10.8% and 7.7%, or $48.0 million and $34.5 million, respectively, of rental revenues for the year ended December 31, 2013. On December 9, 2014, the Company closed on the sale of the 9911 Belward Campus Drive property, which was 100% leased to Human Genome Sciences, Inc. and comprised 4.6% or $22.5 million of rental revenues for the year ended December 31, 2014. These tenants are located in the Company's Maryland, and Boston and San Diego markets, respectively. The inability of these tenants to make lease payments could materially adversely affect the Company’s business.
	The Company generally does not require collateral or other security from our tenants, other than security deposits or letters of credit in select cases.
	Construction and Other Related Commitments
	As of December 31, 2014, the Company had approximately $511.5 million outstanding in commitments primarily related to tenant improvements, leasing commissions, and construction-related capital expenditures, with approximately $393.0 million expected to be paid in 2015, approximately $102.0 million expected to be paid in 2016 and approximately $16.5 million to be paid thereafter.
	Ground Leases
	As of December 31, 2014, the Company had approximately $508.7 million outstanding in commitments related to ground leases with approximately $4.7 million expected to be paid in 2015, approximately $10.0 million expected to be paid in 2016 and 2017, approximately $10.5 million expected to be paid in 2018 and 2019 and approximately $483.5 million expected to be paid thereafter.
	Insurance
	The Company carries insurance coverage on its properties with policy specifications and insured limits that it believes are adequate given the relative risk of loss, cost of the coverage and standard industry practice. However, certain types of losses (such as from the perils of earthquakes, windstorms, terrorism and floods) may be either uninsurable or not economically insurable. Further, certain of the properties are located in areas that are subject to earthquake activity, windstorms and floods. Should a property sustain damage as a result of an earthquake, windstorm or flood, the Company may incur losses due to insurance deductibles, co-payments on insured losses or uninsured losses. Should an uninsured loss occur, the Company could lose some or all of its capital investment, cash flow and anticipated profits related to one or more properties.
	Environmental Matters
	The Company follows a policy of monitoring its properties for the presence of hazardous or toxic substances. The Company is not aware of any environmental liability with respect to the properties that would have a material adverse effect on the Company’s business, assets or results of operations. There can be no assurance that such a material environmental liability does not exist. The existence of any such material environmental liability could have an adverse effect on the Company’s results of operations and cash flow. The Company carries environmental remediation insurance for its properties. This insurance, subject to certain exclusions and deductibles, covers the cost to remediate environmental damage caused by future spills or the historic presence of previously undiscovered hazardous substances, as well as third-party bodily injury and property damage claims related to the release of hazardous substances.
	Legal Proceedings
	Although the Company is involved in legal proceedings arising in the ordinary course of business, as of December 31, 2014, the Company is not currently a party to any legal proceedings nor, to its knowledge, is any legal proceeding threatened against it that it believes would have a material adverse effect on its financial position, results of operations or liquidity.

Quarterly_Financial_Informatio

Quarterly Financial Information of the Parent Company (Notes) (Parent Company)	12 Months Ended
	Dec. 31, 2014
Parent Company
Quarterly Financial Information Disclosure [Line Items]
Quarterly Financial Information [Text Block]	Quarterly Financial Information of the Parent Company (unaudited)
	The Company’s selected quarterly information for the years ended December 31, 2014 and 2013 (in thousands, except per share data) was as follows.
		2014 Quarter Ended(1)
		31-Dec			30-Sep			30-Jun			31-Mar
	Total revenues	$	165,656		$	168,916		$	171,161		$	168,876
	Gain on sale of real estate	136,609			—			—			—
	Net income	144,627			16,976			19,098			20,767
	Net income attributable to noncontrolling interests	(4,278		)	(1,016		)	(462		)	(1,934		)
	Net income available to common stockholders	$	140,349		$	15,960		$	18,636		$	18,833
	Income from continuing operations per share available to common stockholders-basic	$	0.71		$	0.08		$	0.1		$	0.1
	Income from continuing operations per share available to common stockholders-diluted	$	0.7		$	0.08		$	0.1		$	0.1
	Net income per share available to common stockholders-basic	$	0.71		$	0.08		$	0.1		$	0.1
	Net income per share available to common stockholders-diluted	$	0.7		$	0.08		$	0.1		$	0.1
		2013 Quarter Ended(1)
		31-Dec			30-Sep			30-Jun			31-Mar
	Total revenues	$	157,993		$	159,232		$	159,639		$	160,450
	Net income	10,576			4,136			15,037			17,458
	Net (income) / loss attributable to noncontrolling interests	(297		)	111			(234		)	(146		)
	Preferred stock dividends	—			—			—			(2,393		)
	Net income available to common stockholders	$	10,279		$	4,247		$	14,803		$	8,388
	Income from continuing operations per share available to common stockholders - basic and diluted	$	0.05		$	0.02		$	0.08		$	0.05
	Net income per share available to common stockholders - basic and diluted	$	0.05		$	0.02		$	0.08		$	0.05
	-1	The sum of quarterly financial data may vary from the annual data due to rounding.

Quarterly_Financial_Informatio1

Quarterly Financial Information of the Operating Partnership Quarterly Financial Information of the Operating Partnership (BIOMED REALTY, L.P., USD $)	3 Months Ended							12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2014												Dec. 31, 2013	Dec. 31, 2012
BIOMED REALTY, L.P.
Quarterly Financial Information Disclosure [Line Items]
Gain (Loss) on Sale of Properties	$136,609	$0		$0		$0		$136,609												$0	$0
Income (Loss) from Continuing Operations, Per Basic Share	$0.71							$0.99
Income (Loss) from Continuing Operations, Per Basic and Diluted Share		$0	[1]	$0	[1]	$0	[1]													$0.20
Income (Loss) from Continuing Operations, Per Diluted Share	$0.70							$0.98
Earnings Per Share, Basic	$0.71							$0.99
Earnings Per Share, Diluted	$0.70							$0.98
Quarterly Financial Information [Text Block]								Quarterly Financial Information of the Operating Partnership (unaudited)
								The Company’s selected quarterly information for the years ended December 31, 2014 and 2013 (in thousands, except per share data) was as follows.
									2014 Quarter Ended(1)
									31-Dec			30-Sep			30-Jun		31-Mar
								Total revenues	$	165,656		$	168,916		$	171,161	$	168,876
								Gain on sale of real estate	136,609			—			—		—
								Net income	144,627			16,976			19,098		20,767
								Net (income) / loss attributable to noncontrolling interests	(496		)	(587		)	52		(1,413		)
								Net income available to unit holders	$	144,131		$	16,389		$	19,150	$	19,354
								Income from continuing operations per unit available to unit holders-basic	$	0.71		$	0.08		$	0.1	$	0.1
								Income from continuing operations per unit available to unit holders-diluted	$	0.7		$	0.08		$	0.1	$	0.1
								Net income per unit available to unit holders-basic	$	0.71		$	0.08		$	0.1	$	0.1
								Net income per unit available to unit holders-diluted	$	0.7		$	0.08		$	0.1	$	0.1
									2013 Quarter Ended(1)
									31-Dec			30-Sep			30-Jun		31-Mar
								Total revenues	$	157,993		$	159,232		$	159,639	$	160,450
								Net income	10,576			4,136			15,037		17,458
								Net (income) / loss attributable to noncontrolling interests	(12		)	229			29		8
								Preferred unit distributions	—			—			—		(2,393		)
								Net income available to unit holders	$	10,564		$	4,365		$	15,066	$	8,542
								Income from continuing operations per unit available to unit holders - basic and diluted	$	0.05		$	0.02		$	0.08	$	0.05
								Net income per unit available to unit holders - basic and diluted	$	0.05		$	0.02		$	0.08	$	0.05
								-1	The sum of quarterly financial data may vary from the annual data due to rounding.
[1]	The sum of quarterly financial data may vary from the annual data due to rounding.

Schedule_III_Schedule_III_Note

Schedule III Schedule III (Notes)	12 Months Ended
	Dec. 31, 2013
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Text Block]	A reconciliation of historical cost and related accumulated depreciation is as follows (in thousands):
		Year Ended December 31,
		2014			2013			2012
	Investment in real estate:
	Balance at beginning of year	$	6,003,480		$	4,923,166		$	4,402,720
	Property acquisitions	173,907			835,999			395,560
	Property sales	(200,974		)	(4,155		)	(33,048		)
	Improvements	386,601			248,470			157,934
	Balance at end of year	$	6,363,014		$	6,003,480		$	4,923,166
	Accumulated Depreciation:
	Balance at beginning of year	$	(785,578	)	$	(603,450	)	$	(452,474	)
	Depreciation expense	(204,189		)	(183,502		)	(152,506		)
	Property sales	43,328			1,374			1,530
	Balance at end of year	$	(946,439	)	$	(785,578	)	$	(603,450	)

Basis_of_Presentation_and_Summ1

Basis of Presentation and Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Revenue Recognition, Real Estate Transactions, Policy [Policy Text Block]	Gain on Sale of Real Estate
	The Company recognizes gains on sale of real estate when a contract is in place, a closing has taken place, the buyer's initial and continuing involvement is adequate to demonstrate a commitment to pay for the property and the Company does not have a substantial involvement in the property. On December 9, 2014, the Company closed on the sale of the 9911 Belward Campus Drive property located in Rockville, Maryland for approximately $317.2 million in proceeds, net of selling costs, resulting in a gain on sale of approximately $136.6 million.
Principles of Consolidation	Principles of Consolidation
	The consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries, partnerships and limited liability companies it controls, and variable interest entities (“VIEs”) for which the Company has determined itself to be the primary beneficiary. All material intercompany transactions and balances have been eliminated. The Company consolidates entities the Company controls and records a noncontrolling interest for the portions not owned by the Company. Control is determined, where applicable, by the sufficiency of equity invested and the rights of the equity holders, and by the ownership of a majority of the voting interests, with consideration given to the existence of approval or veto rights granted to the minority stockholder. If the minority stockholder holds substantive participating rights, it overcomes the presumption of control by the majority voting interest holder. In contrast, if the minority stockholder simply holds protective rights (such as consent rights over certain actions), it does not overcome the presumption of control by the majority voting interest holder.
	Assets and liabilities of subsidiaries outside the United States with non-U.S. dollar functional currencies are translated into U.S. dollars using exchange rates as of the balance sheet dates. Income and expenses are translated using the average exchange rates for the reporting period. Foreign currency translation adjustments are recorded as a component of other comprehensive income. For the years ended December 31, 2014, 2013 and 2012, total revenues from properties outside the United States were $20.2 million, $18.2 million and $10.3 million, respectively, which represented 3.0%, 2.9% and 2.0% of the Company's total revenues during the respective periods. The Company’s net investments in properties outside the United States were $200.2 million, $190.2 million and $188.8 million at December 31, 2014, 2013 and 2012, respectively.
Investments in Partnerships and Limited Liability Companies	Investments in Partnerships and Limited Liability Companies
	The Company evaluates its investments in limited liability companies and partnerships to determine whether such entities may be a VIE, and, if a VIE, whether the Company is the primary beneficiary. Generally, an entity is determined to be a VIE when either (1) the equity investors (if any) lack one or more of the essential characteristics of a controlling financial interest, (2) the equity investment at risk is insufficient to finance that entity's activities without additional subordinated financial support or (3) the equity investors have voting rights that are not proportionate to their economic interests and the activities of the entity involve or are conducted on behalf of an investor with a disproportionately small voting interest. The primary beneficiary is the entity that has both (1) the power to direct matters that most significantly impact the VIE's economic performance and (2) the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE. The Company considers a variety of factors in identifying the entity that holds the power to direct matters that most significantly impact the VIE's economic performance including, but not limited to, the ability to direct financing, leasing, construction and other operating decisions and activities. In addition, the Company considers the rights of other investors to participate in policy making decisions, to replace or remove the manager and to liquidate or sell the entity. The obligation to absorb losses and the right to receive benefits when a reporting entity is affiliated with a VIE must be based on ownership, contractual, and/or other pecuniary interests in that VIE. At December 31, 2014 and 2013, the Company determined that it is the primary beneficiary in six and five VIEs, respectively, (excluding certain VIEs through its ownership of Wexford Science and Technology, LLC and related entities (collectively, "Wexford") which are discussed below), consisting of single-tenant properties in which the tenant has a fixed-price purchase option, which are consolidated and reflected in the accompanying consolidated financial statements. Selected financial data of the VIEs at December 31, 2014 and 2013 consist of the following (in thousands):
		December 31,				December 31,
		2014				2013
	Investment in real estate, net	$	433,842			$	336,832
	Total assets	493,066				375,443
	Total debt	189,848				143,067
	Total liabilities	203,529				154,953
	If the foregoing conditions do not apply, the Company considers whether a general partner or managing member controls a limited partnership or limited liability company. The general partner in a limited partnership or managing member in a limited liability company is presumed to control that limited partnership or limited liability company. The presumption may be overcome if the limited partners or members have either (1) the substantive ability to dissolve the limited partnership or limited liability company or otherwise remove the general partner or managing member without cause or (2) substantive participating rights, which provide the limited partners or members with the ability to effectively participate in significant decisions that would be expected to be made in the ordinary course of the limited partnership’s or limited liability company’s business and thereby preclude the general partner or managing member from exercising unilateral control over the partnership or company. If these criteria are met and the Company is the general partner or the managing member, as applicable, the consolidation of the partnership or limited liability company is required.
	Except for investments that are consolidated, the Company accounts for investments in entities over which it exercises significant influence, but does not control, under the equity method of accounting. These investments are recorded initially at cost and subsequently adjusted for equity in earnings and cash contributions and distributions. Under the equity method of accounting, the Company’s net equity in the investment is reflected in the consolidated balance sheets and its share of net income or loss is included in the Company’s consolidated statements of operations.
	On a periodic basis, management assesses whether there are any indicators that the carrying value of the Company’s investments in unconsolidated partnerships or limited liability companies may be impaired on a more than temporary basis. An investment is impaired only if management’s estimate of the fair-value of the investment is less than the carrying value of the investment on a more than temporary basis. To the extent impairment has occurred, the loss is measured as the excess of the carrying value of the investment over the fair-value of the investment. Management does not believe that the carrying value of any of the Company’s unconsolidated investments in partnerships or limited liability companies was impaired as of December 31, 2014.
	Historic Tax Credits and New Market Tax Credits
	The Company is a party to certain contractual arrangements with tax credit investors ("TCIs") that were established to enable the TCIs to receive benefits of historic tax credits ("HTCs") and/or new market tax credits ("NMTCs") for certain properties owned by Wexford. During the years ended December 31, 2014 and 2013, Wexford owned ten and nine properties, respectively, that had syndicated HTCs or NMTCs, or both, to TCIs.
	Capital contributions are made by TCIs into special purpose entities that ultimately invest these funds in the entity that owns the subject property that generates the tax credits. The TCIs are allocated substantially all of the tax credits and hold only a noncontrolling interest in the economic risk and rewards of the special purpose entities. HTCs are delivered to the TCI upon substantial completion of the project. NMTCs are allowed for up to 39% of a qualified investment and are delivered to the TCI after the investment has been funded and spent on a qualified business. HTCs are subject to 20% recapture per year beginning one year after the completion of the historic rehabilitation of the subject property. NMTCs are subject to 100% recapture until the end of the seventh year following the qualifying investment. The Company has provided the TCIs with certain guarantees which protect the TCIs from loss should a tax credit recapture event occur. The contractual arrangements with the TCIs include a put/call provision whereby the Company may be obligated or entitled to repurchase the ownership interest of the TCIs in the special purpose entities at the end of the tax credit recapture period. The Company anticipates that either the TCIs will exercise their put rights or the Company will exercise its call rights; however, the Company believes that the put rights are more likely to be exercised.
	The portion of the TCI’s capital contribution that is attributed to the put is recorded at fair-value at inception and is accreted to the expected put price as interest expense in the consolidated statement of operations. At December 31, 2014 and 2013, approximately $5.2 million and $4.3 million of put liabilities were included in other liabilities in the consolidated balance sheets, respectively. The remaining balance of the TCI’s capital contribution is initially recorded in other liabilities in the consolidated balance sheets and will be relieved, upon delivery of the tax credit to the TCI, as a reduction in the carrying value of the subject property, net of allocated expenses. During the years ended December 31, 2014 and 2013, $48.8 million and $34.4 million of tax credits, net of costs and estimated put payments, were contributed by TCIs and were recorded as other liabilities in the consolidated balance sheets, respectively. During the years ended December 31, 2014 and 2013, $55.5 million and $22.4 million of tax credits have been delivered to the TCIs and were reclassified as a reduction of the carrying value of the subject property, respectively. Direct and incremental costs incurred in structuring the transaction are deferred and will be recognized as an increase in the cost basis of the subject property upon the recognition of the related tax credit as discussed above.
	At December 31, 2014 and 2013, the Company determined that certain special purpose entities owning one property and three properties, respectively, under development are VIEs, since there is insufficient capital to finance the remaining development activities without further subordinated financial support. The Company has determined it is the primary beneficiary of these VIEs, because it has the authority to direct the activities which most significantly impact their economic performance. Selected financial data of the VIEs at December 31, 2014 and 2013 consisted of the following (in thousands):
		December 31,			December 31,
		2014			2013
	Investment in real estate, net	$	2,507		$	177,901
	Total assets	24,478			198,968
	Total liabilities	7,467			60,197
Investments in Real Estate, Net	Investments in Real Estate, Net
	Investments in real estate are carried at depreciated cost. Depreciation and amortization are recorded on a straight-line basis over the estimated useful lives of the assets as follows:
	Buildings and improvements	Remaining useful life, not to exceed 40 years
	Tenant improvements	Shorter of the useful lives or the terms of the related leases
	Furniture, fixtures, and equipment (other assets)	Three to five years
	Acquired in-place leases	Non-cancelable term of the related lease
	Acquired management agreements	Non-cancelable term of the related agreement
	Investments in real estate, net consisted of the following (in thousands):
		December 31,				December 31,
		2014				2013
	Land	$	704,958			$	713,955
	Land under development	151,242				119,325
	Buildings and improvements	4,877,135				4,854,175
	Construction in progress	629,679				316,025
		6,363,014				6,003,480
	Accumulated depreciation	(946,439		)		(785,578		)
		$	5,416,575			$	5,217,902
	Purchase accounting is applied to the assets and liabilities of real estate properties in which the Company acquires a controlling interest or a partial interest. The fair-value of tangible assets of an acquired property (which includes land, buildings, and improvements) is determined by valuing the property as if it were vacant, and the “as-if-vacant” value is then allocated to land, buildings and improvements based on management’s determination of the fair-value of these assets. Factors considered by the Company in performing these analyses include an estimate of the carrying costs during the expected lease-up periods, current market conditions and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance and other operating expenses and estimates of lost rental revenue during the expected lease-up periods based on current market demand. Upon the acquisition of a controlling interest of an investment in an unconsolidated partnership, such partnership is consolidated and a gain is recognized equal to the amount in which the fair-value of the noncontrolling interest in such partnership exceeded its carrying value at the time of obtaining control.
	The aggregate value of other acquired intangible assets consisting of acquired in-place leases and acquired management agreements (see deferred leasing costs below) are recorded based on a variety of considerations including, but not necessarily limited to: (1) the value associated with avoiding the cost of originating the acquired in-place leases (i.e. the market cost to execute a lease, including leasing commissions and legal fees, if any); (2) the value associated with lost revenue related to tenant reimbursable operating costs estimated to be incurred during the assumed lease-up period (i.e. real estate taxes and insurance); and (3) the value associated with lost rental revenue from existing leases during the assumed lease-up period (see discussion of the recognition of acquired above-market and below-market leases in Revenue Recognition section below). The fair-value assigned to the acquired management agreements are recorded at the present value (using a discount rate which reflects the risks associated with the management agreements acquired) of the acquired management agreements with certain tenants of the acquired properties. The Company has also considered the existence of a tenant relationship intangible asset, but has not historically allocated any value to tenant relationships apart from acquired in-place leases. The values of in-place leases and management agreements are amortized to expense over the remaining non-cancelable period of the respective leases or agreements. If a lease were to be terminated or if termination is determined to be likely (e.g., in the case of a tenant bankruptcy) prior to its contractual expiration, amortization of all unamortized amounts related to that lease would be accelerated and such amounts written off.
	Costs incurred in connection with the development or construction of properties and improvements are capitalized. Capitalized costs include pre-construction costs essential to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other direct costs incurred during the period of development. The Company capitalizes costs on land and buildings under development until construction is substantially complete and the property is held available for occupancy. Determination of when a development project is substantially complete and when capitalization must cease involves a degree of judgment. The Company considers a construction project as substantially complete and held available for occupancy upon the completion of landlord-owned tenant improvements or when the lessee takes possession of the unimproved space for construction of its own improvements, but no later than one year from cessation of major construction activity. The Company ceases capitalization on the portion substantially completed and occupied or held available for occupancy, and capitalizes only those costs associated with any remaining portion under construction. Interest costs capitalized for the years ended December 31, 2014, 2013 and 2012 were $21.9 million, $14.2 million and $8.6 million, respectively. Payroll costs capitalized for the years ended December 31, 2014, 2013 and 2012 were $4.4 million, $3.6 million and $2.0 million, respectively. Costs associated with acquisitions of businesses are charged to expense.
	Repair and maintenance costs are charged to expense as incurred and significant replacements and betterments are capitalized. Repairs and maintenance costs include all costs that do not extend the useful life of an asset or increase its operating efficiency. Significant replacement and betterments represent costs that extend an asset’s useful life or increase its operating efficiency.
Impairment of Long-Lived Assets and Long-Lived Assets to be Disposed	Impairment of Long-Lived Assets and Long-Lived Assets to be Disposed
	The Company reviews long-lived assets and certain identifiable intangibles for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The review of recoverability is based on an estimate of the future undiscounted cash flows (excluding interest charges) expected to result from the long-lived asset’s use and eventual disposition. These cash flows consider factors such as expected future operating income, trends and prospects, as well as the effects of leasing demand, competition and other factors. If impairment exists due to the inability to recover the carrying value of a long-lived asset, an impairment loss is recorded to the extent that the carrying value exceeds the estimated fair-value of the property. The Company is required to make subjective assessments as to whether there are impairments in the values of its investments in long-lived assets. These assessments have a direct impact on the Company’s net income because recording an impairment loss results in an immediate negative adjustment to net income. The evaluation of anticipated cash flows is highly subjective and is based in part on assumptions regarding future occupancy, rental rates and capital requirements that could differ materially from actual results in future periods. Although the Company’s strategy is to hold its properties over the long-term, if the Company’s strategy changes or market conditions otherwise dictate an earlier sale date, an impairment loss may be recognized to reduce the property to the lower of the carrying amount or fair-value, and such loss could be material.
	In April 2012, the Company completed the exchange of a property for another real estate operating property. As a result, the property disposed of was reclassified as a discontinued operation. This property was written down to its estimated fair-value of $28.0 million, less costs to sell, which resulted in an impairment loss of $4.6 million that is included in loss from discontinued operations for the year ended December 31, 2012. The parties to the exchange determined and agreed upon the fair-value of the property received in the transaction, which the Company considers to be a Level 2 input in the fair-value hierarchy. See Note 12 for discussion of discontinued operations.
Cash and Cash Equivalents	Cash and Cash Equivalents
	Cash and cash equivalents consist of highly liquid investments with original maturities of three months or less. The Company maintains its cash at insured financial institutions. The combined account balances at each institution periodically exceed FDIC insurance coverage, and, as a result, there is a concentration of credit risk related to amounts in excess of FDIC limits. The Company believes that the risk is not significant.
Deferred Leasing Costs, Net	Deferred Leasing Costs, Net
	Leasing commissions and other direct costs associated with obtaining new or renewal leases are recorded at cost and amortized on a straight-line basis over the terms of the respective leases, with remaining terms ranging from less than one year to approximately 20 years as of December 31, 2014. Deferred leasing costs also include the net carrying value of acquired in-place leases and acquired management agreements.
	Deferred leasing costs, net at December 31, 2014 consisted of the following (in thousands):
		Balance at				Accumulated
		December 31, 2014				Amortization				Net
	Acquired in-place leases	$	415,389			$	(271,782	)		$	143,607
	Acquired management agreements	25,801				(22,328		)		3,473
	Deferred leasing and other direct costs	111,290				(38,657		)		72,633
		$	552,480			$	(332,767	)		$	219,713
	Deferred leasing costs, net at December 31, 2013 consisted of the following (in thousands):
		Balance at				Accumulated
		December 31, 2013				Amortization				Net
	Acquired in-place leases	$	365,753			$	(233,935	)		$	131,818
	Acquired management agreements	25,801				(20,053		)		5,748
	Deferred leasing and other direct costs	91,142				(30,641		)		60,501
		$	482,696			$	(284,629	)		$	198,067
	The estimated amortization expense for deferred leasing costs at December 31, 2014 was as follows (in thousands):
	2015	$	37,121
	2016	29,029
	2017	26,596
	2018	22,348
	2019	17,571
	Thereafter	87,048
	Total	$	219,713
Revenue Recognition, Operating Expenses and Lease Terminations	Revenue Recognition, Operating Expenses and Lease Terminations
	The Company commences revenue recognition on its leases based on a number of factors. In most cases, revenue recognition under a lease begins when the lessee takes possession of or controls the physical use of the leased asset. Generally, this occurs on the lease commencement date. In determining what constitutes the leased asset, the Company evaluates whether the Company or the lessee is the owner, for accounting purposes, of the tenant improvements. If the Company is the owner, for accounting purposes, of the tenant improvements, then the leased asset is the finished space and revenue recognition begins when the lessee takes possession of the finished space, typically when the improvements are substantially complete. If the Company concludes that it is not the owner, for accounting purposes, of the tenant improvements (the lessee is the owner), then the leased asset is the unimproved space and any tenant improvement allowances funded under the lease are treated as lease incentives, which reduce revenue recognized on a straight-line basis over the remaining non-cancelable term of the respective lease. In these circumstances, the Company begins revenue recognition when the lessee takes possession of the unimproved space for the lessee to construct improvements. The determination of who is the owner, for accounting purposes, of the tenant improvements determines the nature of the leased asset and when revenue recognition under a lease begins. The Company considers a number of different factors to evaluate whether it or the lessee is the owner of the tenant improvements for accounting purposes. These factors include:
	•	whether the lease stipulates how and on what a tenant improvement allowance may be spent;
	•	whether the tenant or landlord retain legal title to the improvements;
	•	the uniqueness of the improvements;
	•	the expected economic life of the tenant improvements relative to the length of the lease;
	•	the responsible party for construction cost overruns; and
	•	who constructs or directs the construction of the improvements.
	The determination of who owns the tenant improvements, for accounting purposes, is subject to significant judgment. In making that determination, the Company considers all of the above factors. However, no one factor is determinative in reaching a conclusion.
	All leases are classified as operating leases and minimum rents are recognized on a straight-line basis over the term of the related lease. The excess of rents recognized over amounts contractually due pursuant to the underlying leases are included in accrued straight-line rents on the accompanying consolidated balance sheets and contractually due but unpaid rents are included in accounts receivable. Existing leases at acquired properties are reviewed at the time of acquisition to determine if contractual rents are above or below current market rents for the acquired property. An identifiable lease intangible asset or liability is recorded based on the present value (using a discount rate that reflects the risks associated with the acquired leases) of the difference between (1) the contractual amounts to be paid pursuant to the in-place leases and (2) the Company’s estimate of the fair market lease rates for the corresponding in-place leases at acquisition, measured over a period equal to the remaining non-cancelable term of the leases and any fixed rate renewal periods (based on the Company’s assessment of the likelihood that the renewal periods will be exercised). The capitalized above-market lease values are amortized as a reduction of rental revenue on a straight-line basis over the remaining non-cancelable terms of the respective leases. The capitalized below-market lease values are amortized as an increase to rental revenue on a straight-line basis over the remaining non-cancelable terms of the respective leases and any fixed-rate renewal periods, if applicable. If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off.
	The impact of the straight-line rent revenue, acquired above and below market lease revenue, and lease incentive revenue consisted of the following (in thousands):
		Years Ended December 31,
		2014				2013				2012
	Straight-line rent revenue	$	13,197			$	23,136			$	23,288
	Acquired above-market lease revenue	(4,647		)		(11,913		)		(9,977		)
	Acquired below-market lease revenue	6,061				4,325				1,684
	Lease incentive revenue	(2,674		)		(2,295		)		(2,969		)
	Net increase in revenue	$	11,937			$	13,253			$	12,026
	Total estimated minimum rents under non-cancelable operating tenant leases in effect at December 31, 2014 were as follows (in thousands):
	2015	$	451,321
	2016	450,748
	2017	433,538
	2018	377,925
	2019	336,180
	Thereafter	2,300,692
	Total	$	4,350,404
	The estimated amortization for acquired above- and below-market lease revenue and lease incentive revenue at December 31, 2014 was as follows (in thousands):
		2015				2016				2017				2018				2019				Thereafter			Total
	Amortization of:
	Acquired above-market leases	$	(1,895	)		$	(1,307	)		$	(1,179	)		$	(1,132	)		$	(972	)		$	(4,722	)	$	(11,207	)
	Acquired below-market leases	4,042				3,782				3,690				3,656				3,150				17,478			35,798
	Lease incentive	(3,951		)		(3,863		)		(3,420		)		(1,615		)		(1,456		)		(10,109		)	(24,414		)
	Rental operations expenses, consisting of real estate taxes, insurance and common area maintenance costs, are subject to recovery from tenants under the terms of lease agreements. Amounts recovered are dependent on several factors, including occupancy and lease terms. Revenues are recognized in the period the expenses are incurred. The reimbursements are recorded in revenues as tenant recoveries, and the expenses are recorded in rental operations expenses, as the Company is generally the primary obligor with respect to purchasing goods and services from third-party suppliers, has discretion in selecting the supplier and bears the credit risk.
	On an ongoing basis, the Company evaluates the recoverability of tenant balances, including rents receivable, straight-line rents receivable, tenant improvements, deferred leasing costs and any acquisition intangibles. Factors considered by the Company as part of this evaluation include, among other things, the financial strength of the tenant and any guarantors, a review of publicly filed documents and analyst research reports, a review of the tenant's cash balance and estimated cash "burn" rate if the tenant's cash flow from operations is negative, and the tenant's payment history. When it is determined that the recoverability of tenant balances is not probable, an allowance for expected losses related to tenant receivables, including straight-line rents receivable is recorded as a charge to earnings. Upon the termination of a lease, the amortization of tenant improvements, deferred leasing costs and acquisition intangible assets and liabilities is accelerated to the expected termination date as a charge to their respective line items and tenant receivables are written off as a reduction of the allowance in the period in which the balance is deemed to be no longer collectible. For financial reporting purposes, a lease is treated as terminated upon a tenant filing for bankruptcy, when a space is abandoned and a tenant ceases rent payments, or when other circumstances indicate that termination of a tenant’s lease is probable (e.g., eviction). Lease termination fees are recognized in other income when the related leases are canceled, the amounts to be received are fixed and determinable and collectability is assured, and when the Company has no continuing obligation to provide services to such former tenants.
Allowance For Doubtful Accounts	Allowance for Doubtful Accounts
	The Company maintains an allowance for doubtful accounts for estimated losses resulting from the inability of tenants to make required rent and tenant recovery payments or defaults. The Company maintains an allowance for accrued straight-line rents. The determination of this allowance is based on the tenants’ payment history and current credit status. Bad debt expense included in rental operations expenses was approximately $900,000, $931,000 and $1.7 million for the years ended December 31, 2014, 2013 and 2012, respectively. The Company’s allowance for doubtful accounts included in accounts receivable, net and accrued straight line rent, net was approximately $2.4 million, $2.3 million and $4.2 million as of December 31, 2014, 2013 and 2012, respectively.
Investments	Investments
	The Company, through its Operating Partnership, holds equity investments in certain publicly-traded companies and privately-held companies primarily involved in the life science industry. The Company may accept equity investments from tenants in lieu of cash rents, as prepaid rent pursuant to the execution of a lease, or as additional consideration for a lease termination. The Company does not acquire investments for trading purposes and, as a result, all of the Company’s investments in publicly-traded companies are considered “available-for-sale” and are recorded at fair-value. Changes in the fair-value of investments classified as available-for-sale are recorded in comprehensive income. The fair-value of the Company’s equity investments in publicly-traded companies is determined based upon the closing trading price of the equity security as of the balance sheet date, with unrealized gains and losses shown as a separate component of equity. Investments in privately-held companies are generally accounted for under the cost method, because the Company does not influence any operating or financial policies of the companies in which it invests. The classification of investments is determined at the time each investment is made, and such determination is reevaluated at each balance sheet date. The cost of investments sold is determined by the specific identification method, with net realized gains and losses included in other income. For all investments, if a decline in the fair-value of an investment below its carrying value is determined to be other-than-temporary, such investment is written down to its estimated fair-value with a non-cash charge to earnings. The factors that the Company considers in making these assessments include, but are not limited to, market prices, market conditions, available financing, prospects for favorable or unfavorable clinical trial results, new product initiatives and new collaborative agreements.
	Investments in equity securities, which are included in other assets on the accompanying consolidated balance sheets, consisted of the following (in thousands):
		December 31,				December 31,
		2014				2013
	Available-for-sale securities, historical cost	$	10,280			$	8,543
	Unrealized gain, net	48,341				11,023
	Available-for-sale securities, fair-value (1)	58,621				19,566
	Privately-held securities, cost basis	43,428				18,485
	Total equity securities	$	102,049			$	38,051
	-1	Determination of fair-value is classified as Level 1 in the fair-value hierarchy based on the use of quoted prices in active markets.
	The Company holds investments in available-for-sale securities of certain publicly-traded companies. Certain of these investments have fair-values less than the Company’s cost basis, net of previous other-than-temporary impairment in these securities due to decreases in their respective stock prices during the year ended December 31, 2014. However, management has the intent and ability to retain the investments for a period of time sufficient to allow for an anticipated recovery in their market value. Management will continue to periodically evaluate whether any investment, the fair-value of which is less than the Company’s cost basis, should be considered other-than-temporarily impaired. If other-than-temporary impairment is considered to exist, the related unrealized loss will be reclassified from accumulated other comprehensive loss and recorded as a reduction of net income.
	The Company also holds investments in securities of certain privately-held companies and funds, which are recorded at cost basis due to the Company’s lack of control or significant influence over such companies and funds.
	During the years ended December 31, 2014 and 2013, the Company recorded impairment charges of $2.0 million and $2.8 million, respectively. Impairment charges are included in other expense in the consolidated statements of operations and relate to the Company’s investments in two privately-held companies. Other than these investments there were no identified events or changes in circumstances that may have a significant adverse effect on the carrying value of the Company’s cost basis investments and therefore, no evaluation of impairment was performed during the year ended December 31, 2014 on the Company’s remaining cost basis investments.
Share-based Payments	Share-Based Payments
	All share-based payments to employees are recognized in the consolidated statement of operations based on their fair-value. Through December 31, 2014, the Company had awarded restricted stock of the Parent Company and LTIP unit grants of the Operating Partnership under its incentive award plan, both of which are valued based on the closing market price of the underlying common stock on the date of grant, and had not granted any stock options. During the years ended December 31, 2014, 2013 and 2012, the Parent Company awarded performance units (the “Performance Units”) to certain of its executive officers. Each Performance Unit represents a contingent right to receive one share of the Parent Company’s common stock if vesting conditions are satisfied. The grant date fair-value of the Performance Units was estimated using a Monte Carlo simulation which considered the likelihood of achieving the vesting conditions (see Note 13 for further information on the fair-value of the Performance Units). The fair-value of all share-based payments is amortized to general and administrative expense and rental operations expense over the relevant service period, adjusted for anticipated forfeitures.
Assets and Liabilities Measured at Fair-Value	Assets and Liabilities Measured at Fair-Value
	The Company measures financial instruments and other items at fair-value where required under GAAP, but has elected not to measure any additional financial instruments and other items at fair-value as permitted under fair-value option accounting guidance.
	Fair-value measurement is determined based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering market participant assumptions in fair-value measurements, there is a fair-value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity’s own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy).
	Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability, which are typically based on an entity’s own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair-value measurement is based on inputs from different levels of the fair-value hierarchy, the level in the fair-value hierarchy within which the entire fair-value measurement falls is based on the lowest level input that is significant to the fair-value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair-value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.
	The Company has used interest rate swaps 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. The fair-values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. 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. In adjusting the fair-value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees.
	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 itself and its counterparties. However, as of December 31, 2014, the Company has determined that the impact of the credit valuation adjustments on the overall valuation of its derivative positions is not significant. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair-value hierarchy (see Note 9).
	The valuation of the Company’s investments in publicly-traded companies utilizes observable market-based inputs, based on the closing trading price of securities as of the balance sheet date, therefore, the Company has determined that valuations of available-for-sale securities are classified in Level 1 of the fair-value hierarchy.
	No other assets or liabilities are measured at fair-value on a recurring basis, or have been measured at fair-value on a non-recurring basis subsequent to initial recognition, in the accompanying consolidated balance sheets as of December 31, 2014 and 2013.
Derivative Instruments	Derivative Instruments
	The Company records all derivatives on the consolidated balance sheets at fair-value. In determining the fair-value of its derivatives, the Company considers the credit risk of its counterparties and the Company. These counterparties are generally larger financial institutions engaged in providing a variety of financial services. These institutions generally face similar risks regarding adverse changes in market and economic conditions, including, but not limited to, fluctuations in interest rates, exchange rates, equity and commodity prices and credit spreads. The ongoing disruptions in the financial markets have heightened the risks to these institutions. While management believes that its counterparties will meet their obligations under the derivative contracts, it is possible that defaults may occur.
	The accounting for changes in the fair-value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair-value of an asset, liability, or firm commitment attributable to a particular risk, such as interest rate risk, are considered fair-value hedges. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Derivatives may also be designated as hedges of the foreign currency exposure of a net investment in a foreign operation. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair-value of the hedged asset or liability that are attributable to the hedged risk in a fair-value hedge or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risks, even though hedge accounting does not apply or the Company elects not to apply hedge accounting.
	For derivatives designated as cash flow hedges, the effective portion of changes in the fair-value of the derivative is initially reported in other comprehensive income (outside of earnings) and subsequently reclassified to earnings in the period in which the hedged transaction affects earnings. If charges relating to the hedged transaction are being deferred pursuant to redevelopment or development activities, the effective portion of changes in the fair-value of the derivative are also deferred in accumulated other comprehensive income on the consolidated balance sheet, and are amortized to the income statement once the deferred charges from the hedged transaction begin again to affect earnings. The ineffective portion of changes in the fair-value of the derivative is recognized directly in earnings. The Company assesses the effectiveness of each hedging relationship by comparing the changes in cash flows of the derivative hedging instrument with the changes in cash flows of the designated hedged item or transaction. For derivatives that are not classified as hedges, changes in the fair-value of the derivative are recognized directly in earnings in the period in which the change occurs.
	The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of its debt funding and the use of derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known or expected cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s investments and borrowings.
	The Company’s primary objective in using derivatives is to add stability to interest expense and to manage its exposure to interest rate movements or other identified risks. To accomplish this objective, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying principal amount. During the years ended December 31, 2014, 2013 and 2012, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt and future variability in the interest-related cash flows from forecasted issuances of debt (see Note 9). The Company formally documents the hedging relationships for all derivative instruments, has historically accounted for its interest rate swap agreements as cash flow hedges, and does not use derivatives for trading or speculative purposes.
Equity Offering Costs	Equity Offering Costs
	Underwriting commissions and offering costs are reflected as a reduction of proceeds.
Income Taxes of the Parent Company / Operating Partnership	Income Taxes of the Parent Company
	The Parent Company has elected to be taxed as a REIT under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended. The Parent Company believes it has qualified and continues to qualify as a REIT. A REIT is generally not subject to federal income tax on that portion of its taxable income that is distributed to its stockholders. Accordingly, no provision has been made for federal income taxes in the accompanying consolidated financial statements. REITs are subject to a number of organizational and operational requirements. If the Parent Company fails to qualify as a REIT in any taxable year, the Parent Company will be subject to federal income tax (including any applicable alternative minimum tax) and, in most of the states, state income tax on its taxable income at regular corporate tax rates. The Parent Company is subject to certain state and local taxes.
	Income Taxes of the Operating Partnership
	As a partnership, the allocated share of income of the Operating Partnership is included in the income tax returns of the general and limited partners. Accordingly, no accounting for income taxes is required in the accompanying consolidated financial statements. The Operating Partnership may be subject to certain state or local taxes on its income and property.
	The Operating Partnership has formed certain taxable REIT subsidiaries (each a “TRS”) on behalf of the Parent Company. In general, each TRS may perform non-customary services for tenants, hold assets that the Parent Company cannot hold directly and, except for the operation or management of health care facilities or lodging facilities or the providing of any person, under a franchise, license or otherwise, rights to any brand name under which any lodging facility or health care facility is operated, may engage in any real estate or non-real estate related business. Each TRS is subject to corporate federal and state income taxes on its taxable income at regular corporate tax rates. There is no tax provision for any TRS for the periods presented in the accompanying consolidated statements of operations due to net operating losses incurred. No tax benefits have been recorded since it is not considered more likely than not that the deferred tax asset related to the net operating loss carryforwards will be utilized.
Dividends and Distributions	Dividends and Distributions
	Earnings and profits, which determine the taxability of dividends and distributions to stockholders, will differ from income reported for financial reporting purposes due to the difference for federal income tax purposes in the treatment of revenue recognition, compensation expense, and in the estimated useful lives of real estate assets used to compute depreciation.
	The income tax treatment for dividends was as follows:
		For the Years Ended December 31,
		2014							2013							2012
		Per Share				%			Per Share				%			Per Share				%
	Common stock:
	Ordinary income	$	0.5			38.46	%		$	0.94			100	%		$	0.63			74.12	%
	Capital gain	0.8				61.54			—				—			—				—
	Return of capital	—				—			—				—	%		0.22				25.88	%
	Total	$	1.3			100	%		$	0.94			100	%		$	0.85			100	%
	Preferred stock:
	Ordinary income	$	—			—	%		$	0.76			100	%		$	1.84			100	%
	Capital gain	—				—			—				—			—				—
	Return of capital	—				—			—				—			—				—
	Total	$	—			—	%		$	0.76			100	%		$	1.84			100	%
Construction Loan Receivable	Construction Loan Receivable
	The Company had a $255.0 million interest in a $355.0 million construction loan secured by first priority mortgages on a 1.1 million square foot laboratory, office and retail development project located in Boston, Massachusetts, which is 95% leased to Vertex Pharmaceuticals Incorporated to serve as its new corporate headquarters. As of December 31, 2013, the Company had invested approximately $151.8 million in the construction loan, which is included in other assets on the Company's consolidated balance sheet. In May 2014, the borrower repaid the then outstanding principal and accrued interest balance prior to maturity, of which the Company's portion was approximately $191.2 million. The Company also received prepayment fees of approximately $8.1 million, resulting in other revenue of $7.5 million, net of deferred loan fees write-offs.
Lease Termination	Lease Termination
	During the years ended December 31, 2014, 2013 and 2012, the Company recorded lease termination revenue, net of write-offs of lease intangibles, included in other revenue on the consolidated statement of operations of approximately $12.6 million, $42.8 million and $3.5 million, respectively. Lease termination revenue for the year ended December 31, 2014 primarily related to the early termination of leases at three of the Company's properties. Lease termination revenue for the year ended December 31, 2013 primarily related to the termination of a lease with Elan Corporation (“Elan”) at the Company’s Science Center at Oyster Point property for which Elan paid the Company $46.5 million, and the termination of a lease effective August 2013 with Merck at the Company's 320 Bent Street property for which Merck paid the Company $8.7 million in August 2012. Lease termination revenue for the year ended December 31, 2012 primarily related to the termination of the lease with Merck.
Management's Estimates	Management’s Estimates
	Management has made a number of estimates and assumptions relating to the reporting of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reporting of revenue and expenses during the reporting period to prepare these consolidated financial statements in conformity with GAAP. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and reported amounts of revenue and expenses that are not readily apparent from other sources. Actual results could differ from those estimates under different assumptions or conditions.
New Accounting Pronouncements, Policy [Policy Text Block]	New Accounting Pronouncement
	In April 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update No. 2014-8, "Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity" ("ASU 2014-8"). ASU 2014-8 requires a disposal of a component to meet a higher threshold in order to be reported as a discontinued operation in an entity’s financial statements. The threshold is defined as a strategic shift that has, or will have, a major effect on an entity’s operations and financial results such as a disposal of a major geographical area or a major line of business. This new guidance is effective for the Company beginning in the first quarter of 2015, with early adoption permitted under certain circumstances. During the year ended December 31, 2014, the Company adopted the guidance early in connection with the sale of the 9911 Belward Campus Drive property, which was not determined to be a disposal of a major geographical area or a major line of business.

Basis_of_Presentation_and_Summ2

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Schedule of Variable Interest Entities, Wexford	Selected financial data of the VIEs at December 31, 2014 and 2013 consisted of the following (in thousands):
		December 31,			December 31,
		2014			2013
	Investment in real estate, net	$	2,507		$	177,901
	Total assets	24,478			198,968
	Total liabilities	7,467			60,197
Selected Financial Data of the VIEs	Selected financial data of the VIEs at December 31, 2014 and 2013 consist of the following (in thousands):
		December 31,				December 31,
		2014				2013
	Investment in real estate, net	$	433,842			$	336,832
	Total assets	493,066				375,443
	Total debt	189,848				143,067
	Total liabilities	203,529				154,953
Investments in Real Estate, Net	Investments in real estate, net consisted of the following (in thousands):
		December 31,				December 31,
		2014				2013
	Land	$	704,958			$	713,955
	Land under development	151,242				119,325
	Buildings and improvements	4,877,135				4,854,175
	Construction in progress	629,679				316,025
		6,363,014				6,003,480
	Accumulated depreciation	(946,439		)		(785,578		)
		$	5,416,575			$	5,217,902
Deferred Leasing Costs, Net	Deferred leasing costs, net at December 31, 2014 consisted of the following (in thousands):
		Balance at				Accumulated
		December 31, 2014				Amortization				Net
	Acquired in-place leases	$	415,389			$	(271,782	)		$	143,607
	Acquired management agreements	25,801				(22,328		)		3,473
	Deferred leasing and other direct costs	111,290				(38,657		)		72,633
		$	552,480			$	(332,767	)		$	219,713
	Deferred leasing costs, net at December 31, 2013 consisted of the following (in thousands):
		Balance at				Accumulated
		December 31, 2013				Amortization				Net
	Acquired in-place leases	$	365,753			$	(233,935	)		$	131,818
	Acquired management agreements	25,801				(20,053		)		5,748
	Deferred leasing and other direct costs	91,142				(30,641		)		60,501
		$	482,696			$	(284,629	)		$	198,067
Deferred Leasing Costs - Estimated Amortization Expense	The estimated amortization expense for deferred leasing costs at December 31, 2014 was as follows (in thousands):
	2015	$	37,121
	2016	29,029
	2017	26,596
	2018	22,348
	2019	17,571
	Thereafter	87,048
	Total	$	219,713
Impact Of Straight Line Rent Revenue Acquired Above And Below Market Lease Revenue And Lease Incentive Revenue [Table Text Block]	The impact of the straight-line rent revenue, acquired above and below market lease revenue, and lease incentive revenue consisted of the following (in thousands):
		Years Ended December 31,
		2014				2013				2012
	Straight-line rent revenue	$	13,197			$	23,136			$	23,288
	Acquired above-market lease revenue	(4,647		)		(11,913		)		(9,977		)
	Acquired below-market lease revenue	6,061				4,325				1,684
	Lease incentive revenue	(2,674		)		(2,295		)		(2,969		)
	Net increase in revenue	$	11,937			$	13,253			$	12,026
Estimated Minimum Rents	Total estimated minimum rents under non-cancelable operating tenant leases in effect at December 31, 2014 were as follows (in thousands):
	2015	$	451,321
	2016	450,748
	2017	433,538
	2018	377,925
	2019	336,180
	Thereafter	2,300,692
	Total	$	4,350,404
Revenue Recognition - Estimated Amortization Expense	The estimated amortization for acquired above- and below-market lease revenue and lease incentive revenue at December 31, 2014 was as follows (in thousands):
		2015				2016				2017				2018				2019				Thereafter			Total
	Amortization of:
	Acquired above-market leases	$	(1,895	)		$	(1,307	)		$	(1,179	)		$	(1,132	)		$	(972	)		$	(4,722	)	$	(11,207	)
	Acquired below-market leases	4,042				3,782				3,690				3,656				3,150				17,478			35,798
	Lease incentive	(3,951		)		(3,863		)		(3,420		)		(1,615		)		(1,456		)		(10,109		)	(24,414		)
Investments in Equity Securities	Investments in equity securities, which are included in other assets on the accompanying consolidated balance sheets, consisted of the following (in thousands):
		December 31,				December 31,
		2014				2013
	Available-for-sale securities, historical cost	$	10,280			$	8,543
	Unrealized gain, net	48,341				11,023
	Available-for-sale securities, fair-value (1)	58,621				19,566
	Privately-held securities, cost basis	43,428				18,485
	Total equity securities	$	102,049			$	38,051
	-1	Determination of fair-value is classified as Level 1 in the fair-value hierarchy based on the use of quoted prices in active markets.
Income Tax Treatment for Dividends	The income tax treatment for dividends was as follows:
		For the Years Ended December 31,
		2014							2013							2012
		Per Share				%			Per Share				%			Per Share				%
	Common stock:
	Ordinary income	$	0.5			38.46	%		$	0.94			100	%		$	0.63			74.12	%
	Capital gain	0.8				61.54			—				—			—				—
	Return of capital	—				—			—				—	%		0.22				25.88	%
	Total	$	1.3			100	%		$	0.94			100	%		$	0.85			100	%
	Preferred stock:
	Ordinary income	$	—			—	%		$	0.76			100	%		$	1.84			100	%
	Capital gain	—				—			—				—			—				—
	Return of capital	—				—			—				—			—				—
	Total	$	—			—	%		$	0.76			100	%		$	1.84			100	%

Equity_of_the_Parent_Company_T

Equity of the Parent Company (Tables)	12 Months Ended
	Dec. 31, 2014
Equity of the Parent Company
Dividends and Distributions	Dividends and Distributions
	The following table lists the dividends and distributions declared by the Parent Company and the Operating Partnership during the year ended December 31, 2014:
	Declaration Date		Securities Class		Amount Per				Period Covered		Dividend and		Dividend and
					Share/Unit						Distribution		Distribution Amount
											Payable Date
													(In thousands)
	March 17, 2014		Common stock and OP units		$	0.25			January 1, 2014 to March 31, 2014		April 15, 2014		$	49,479
	June 16, 2014		Common stock and OP units		$	0.25			April 1, 2014 to June 30, 2014		July 15, 2014		$	49,483
	September 15, 2014		Common stock and OP units		$	0.25			July 1, 2014 to September 30, 2014		October 15, 2014		$	50,714
	December 15, 2014		Common stock and OP units		$	0.26			October 1, 2014 to December 31, 2014		January 15, 2015		$	52,740
	In addition to the regularly scheduled quarterly dividends included in the table above, on December 11, 2014, the Company's Board of Directors declared a special cash dividend of $0.30 per share of common stock for a total distribution amount of approximately $60.9 million paid on December 29, 2014 to stockholders of record at the close of business on December 22, 2014.
	Total 2014 dividends and distributions declared on common stock and OP units through December 31, 2014 amounted to $263.3 million.
Changes in Accumulated Other Comprehensive Loss by Component	Changes in Accumulated Other Comprehensive Income / (Loss) by Component
		Foreign currency translation adjustments				Unrealized gains on available- for-sale securities				Gain / (loss) on derivative instruments				Total
	Balance at December 31, 2013	$	4,006			$	9,186			$	(43,855	)		$	(30,663	)
	Other comprehensive (loss) / income before reclassifications	(1,639		)		46,640				(6,625		)		38,376
	Amounts reclassified from accumulated other comprehensive income (1)	—				(9,322		)		10,259				937
	Net other comprehensive (loss) / income	(1,639		)		37,318				3,634				39,313
	Net other comprehensive income allocable to noncontrolling interest	$	—			$	(7,772	)		$	—			$	(7,772	)
	Balance as of December 31, 2014	$	2,367			$	38,732			$	(40,221	)		$	878
	-1	Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of operations. See Note 9 for further information.
Vested Ownership Interests	The following table shows the vested ownership interests in the Operating Partnership:
		December 31, 2014						December 31, 2013
		Operating Partnership Units and LTIP Units			Percentage of Total			Operating Partnership Units and LTIP Units			Percentage of Total
	BioMed Realty Trust	196,031,538			97.4	%		190,676,428			97.3	%
	Noncontrolling interest consisting of:
	Operating partnership and LTIP units held by employees and related parties	2,645,888			1.3	%		2,656,388			1.4	%
	Operating partnership and LTIP units held by third parties	2,627,145			1.3	%		2,627,145			1.3	%
	Total	201,304,571			100	%		195,959,961			100	%
Parent Company
Equity of the Parent Company
Changes in Accumulated Other Comprehensive Loss by Component	Changes in Accumulated Other Comprehensive Loss by Component
		Foreign currency translation adjustments				Unrealized gains on available-for-sale securities				Gain / (loss) on derivative instruments				Total
	Balance at December 31, 2013	$	3,905			$	8,938			$	(45,766	)		$	(32,923	)
	Other comprehensive (loss) / income before reclassifications	(1,639		)		46,640				(6,625		)		38,376
	Amounts reclassified from accumulated other comprehensive income (1)	—				(9,322		)		10,259				937
	Net other comprehensive (loss) / income	(1,639		)		37,318				3,634				39,313
	Net other comprehensive loss / (income) allocable to noncontrolling interests	43				(8,551		)		(96		)		(8,604		)
	Balance as of December 31, 2014	$	2,309			$	37,705			$	(42,228	)		$	(2,214	)
	-1	Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of operations. See Note 9 for further information.

Capital_of_the_Operating_Partn1

Capital of the Operating Partnership Capital of the Operating Partnership (Tables)	12 Months Ended
	Dec. 31, 2014
Statement of Partners' Capital [Abstract]
Changes in Accumulated Other Comprehensive Loss by Component	Changes in Accumulated Other Comprehensive Income / (Loss) by Component
		Foreign currency translation adjustments			Unrealized gains on available- for-sale securities			Gain / (loss) on derivative instruments			Total
	Balance at December 31, 2013	$	4,006		$	9,186		$	(43,855	)	$	(30,663	)
	Other comprehensive (loss) / income before reclassifications	(1,639		)	46,640			(6,625		)	38,376
	Amounts reclassified from accumulated other comprehensive income (1)	—			(9,322		)	10,259			937
	Net other comprehensive (loss) / income	(1,639		)	37,318			3,634			39,313
	Net other comprehensive income allocable to noncontrolling interest	$	—		$	(7,772	)	$	—		$	(7,772	)
	Balance as of December 31, 2014	$	2,367		$	38,732		$	(40,221	)	$	878
	-1	Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of operations. See Note 9 for further information.

Debt_Tables

Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Summary of the Operating Partnership's Outstanding Consolidated Debt	The following is a summary of the Operating Partnership’s outstanding consolidated debt as of December 31, 2014 and December 31, 2013 (dollars in thousands):
		Stated Interest Rate		Effective Interest Rate		Principal Balance
						December 31,			December 31,			Maturity Date
						2014			2013
	Mortgage Notes Payable
	9900 Belward Campus Drive	5.64	%	3.99	%	$	10,486		$	10,631		July 1, 2017
	9901 Belward Campus Drive	5.64	%	3.99	%	12,913			13,091			July 1, 2017
	Center for Life Science | Boston (1)	7.75	%	7.75	%	—			334,447			June 30, 2014
	100 College Street (2)	2.4	%	2.4	%	82,210			—			August 2, 2016
	4320 Forest Park Avenue	4	%	2.7	%	21,000			21,000			June 30, 2015
	300 George Street (2)	6.2	%	4.91	%	45,052			—			July 1, 2025
	Hershey Center for Applied Research	6.15	%	4.71	%	12,938			13,449			May 5, 2027
	500 Kendall Street (Kendall D)	6.38	%	5.45	%	55,545			57,927			December 1, 2018
	Shady Grove Road	5.97	%	5.97	%	141,131			143,067			September 1, 2016
	University of Maryland BioPark I	5.93	%	4.69	%	16,056			16,752			May 15, 2025
	University of Maryland BioPark II	5.2	%	4.33	%	61,905			62,946			September 5, 2021
	University of Maryland BioPark Garage	5.2	%	4.33	%	4,660			4,738			September 1, 2021
	University of Miami Life Science & Technology Park	4	%	2.89	%	20,000			20,000			February 1, 2016
						483,896			698,048
	Unamortized premiums					12,861			11,276
	Mortgage notes payable, net					496,757			709,324
	Exchangeable Senior Notes	3.75	%	3.75	%	95,678			180,000			January 30, 2015
	Notes due 2016	3.85	%	3.99	%	400,000			400,000			April 15, 2016
	Notes due 2019	2.63	%	2.72	%	400,000			—			May 1, 2019
	Notes due 2020	6.13	%	6.27	%	250,000			250,000			April 15, 2020
	Notes due 2022	4.25	%	4.36	%	250,000			250,000			July 15, 2022
						1,300,000			900,000
	Unamortized discounts					(6,097		)	(4,917		)
	Unsecured senior notes, net					1,293,903			895,083
	Term Loan due 2017 - U.S. dollar (3)	1.57	%	2.39	%	243,596			243,596			March 30, 2017
	Term Loan due 2017 - GBP (3)	1.9	%	2.14	%	155,730			165,190			March 30, 2017
	Term Loan due 2018	1.36	%	1.67	%	350,000			350,000			March 24, 2018
	Unsecured senior term loans					749,326			758,786
	Unsecured line of credit (4)	1.27	%	1.27	%	84,000			128,000			March 24, 2018
	Total consolidated debt					$	2,719,664		$	2,671,193
	-1	On April 1, 2014, the Operating Partnership repaid in full the mortgage loan secured by the Company's Center for Life Science | Boston property prior to its scheduled maturity date.
	-2	Mortgage notes payable assumed on April 4, 2014 in connection with the acquisition of the related properties.
	-3	In August 2012, the Operating Partnership converted approximately $156.4 million of outstanding borrowings into British pounds sterling (“GBP”) equal to £100.0 million, which was designated as a net investment hedge to mitigate the risk of fluctuations in foreign currency exchange rates. The principal balance represents the U.S. dollar amount based on the exchange rates of $1.56 to £1.00 and $1.65 to £1.00 at December 31, 2014 and December 31, 2013, respectively. The effective interest rate includes the impact of interest rate swap agreements (see Note 9 for further discussion of interest rate swap agreements).
	-4	At December 31, 2014, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $816.0 million.
Principal Payments Due for Operating Partnership's Consolidated Indebtedness	Maturities of Long-Term Debt
	As of December 31, 2014, principal payments due for the Operating Partnership’s consolidated indebtedness (excluding debt premiums and discounts) were as follows (in thousands):
	2015 (1)	$	127,320
	2016	650,618
	2017	431,632
	2018	481,804
	2019	405,724
	Thereafter	615,802
		$	2,712,900
	-1	Includes $95.7 million in principal payments of the Exchangeable Senior Notes based on

Earnings_Per_Share_of_the_Pare1

Earnings Per Share of the Parent Company (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share, Basic and Diluted [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Computations of basic and diluted earnings per share (in thousands, except share data) were as follows:
		Years Ended December 31,
		2014			2013			2012
	Basic earnings per share:
	Income from continuing operations	$	201,468		$	47,209		$	16,133
	Income from continuing operations attributable to noncontrolling interests	(7,690		)	(565		)	(20		)
	Preferred stock dividends	—			(2,393		)	(14,603		)
	Cost on redemption of preferred stock	—			(6,531		)	—
	Net income allocable and distributions in excess of earnings to participating securities (continuing operations)	(1,954		)	(1,350		)	(1,300		)
	Income from continuing operations available to common stockholders - basic	191,824			36,370			210
	Loss from discontinued operations	—			—			(4,370		)
	Loss from discontinued operations attributable to noncontrolling interests	—			—			82
	Loss from discontinued operations available to common stockholders - basic	—			—			(4,288		)
	Net income / (loss) available to common stockholders - basic	$	191,824		$	36,370		$	(4,078	)
	Diluted earnings per share:
	Income from continuing operations available to common stockholders - basic	191,824			36,370			210
	Income from continuing operations attributable to noncontrolling interests in Operating Partnership	5,246			819			29
	Interest expense on Exchangeable Senior Notes	5,533			—			—
	Income from continuing operations available to common stockholders - diluted	202,603			37,189			239
	Loss from discontinued operations available to common stockholders - basic and diluted	—			—			(4,288		)
	Loss from discontinued operations attributable to noncontrolling interests in the Operating Partnership	—			—			(82		)
	Loss from discontinued operations available to common stockholders - basic and diluted	—			—			(4,370		)
	Net income / (loss) available to common stockholders - diluted	$	202,603		$	37,189		$	(4,131	)
	Weighted-average common shares outstanding:
	Basic	193,003,934			182,043,391			152,752,086
	Incremental shares from assumed conversion:
	Performance units	191,180			63,017			—
	Operating partnership and LTIP units	5,406,682			4,290,614			2,948,301
	Shares issuable upon settlement of the exchange feature of the Exchangeable Senior Notes	8,631,164			—			—
	Diluted	207,232,960			186,397,022			155,700,387
	Basic and diluted earnings per share:
	Income from continuing operations per share available to common stockholders - basic	$	0.99		$	0.2		$	—
	Income from continuing operations per share available to common stockholders - diluted	$	0.98		$	0.2		$	—
	Loss from discontinued operations per share available to common stockholders - basic and diluted	$	—		$	—		$	(0.03	)
	Net income / (loss) per share available to common stockholders - basic	$	0.99		$	0.2		$	(0.03	)
	Net income / (loss) per share available to common stockholders - diluted	$	0.98		$	0.2		$	(0.03	)

Earnings_Per_Unit_of_the_Opera1

Earnings Per Unit of the Operating Partnership (Tables)	12 Months Ended
	Dec. 31, 2014
Partnership Income [Abstract]
Computations of Basic and Diluted Earnings Per Unit	Computations of basic and diluted earnings per unit (in thousands, except unit data) were as follows:
		Years Ended December 31,
		2014			2013			2012
	Basic earnings per unit:
	Income from continuing operations	$	201,468		$	47,209		$	16,133
	(Income) / Loss from continuing operations attributable to noncontrolling interests	(2,444		)	254			8
	Preferred unit distributions	—			(2,393		)	(14,603		)
	Cost on redemption of preferred units	—			(6,531		)	—
	Net income allocable and distributions in excess of earnings to participating securities (continuing operations)	(1,954		)	(1,354		)	(1,326		)
	Income from continuing operations available to unit holders - basic	197,070			37,185			212
	Loss from discontinued operations - basic	—			—			(4,370		)
	Net income / (loss) available to unit holders - basic	$	197,070		$	37,185		$	(4,158	)
	Diluted earnings per unit
	Income from continuing operations available to unit holders - basic	197,070			37,185			212
	Interest expense on Exchangeable Senior Notes	5,533			—			—
	Income from continuing operations available to unit holders - diluted	202,603			37,185			212
	Loss from discontinued operations available to unit holders - diluted	—			—			(4,370		)
	Net income / (loss) available to common unit holders - diluted	202,603			37,185			(4,158		)
	Weighted-average units outstanding:
	Basic	198,410,616			186,333,292			155,670,931
	Incremental units from assumed conversion:
	Performance units	191,180			63,017			—
	Units issuable upon settlement of the exchange feature of the Exchangeable Senior Notes	8,631,164			—			—
	Diluted	207,232,960			186,396,309			155,670,931
	Basic and diluted earnings per unit:
	Income from continuing operations per unit available to unit holders - basic	$	0.99		$	0.2		$	—
	Income from continuing operations per unit available to unit holders - diluted	$	0.98		$	0.2		$	—
	Loss from discontinued operations per share available to unit holders - basic and diluted	$	—		$	—		$	(0.03	)
	Net income / (loss) per unit available to unit holders - basic	$	0.99		$	0.2		$	(0.03	)
	Net income / (loss) per unit available to unit holders - diluted	$	0.98		$	0.2		$	(0.03	)

Investment_in_Unconsolidated_P1

Investment in Unconsolidated Partnerships (Tables)	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Summary of Unconsolidated Partnerships	The accompanying consolidated financial statements include investments in two limited liability companies with Prudential Real Estate Investors (“PREI”), 10165 McKellar Court, L.P. (“McKellar Court”), a limited partnership with Quidel Corporation, the tenant which occupies the McKellar Court property and BioPark Fremont, LLC ("BioPark Fremont"), a limited liability company with RPC Poppleton, LLC. General information on the PREI limited liability companies, the McKellar Court partnership and BioPark Fremont (each referred to in this footnote individually as a “partnership” and collectively as the “partnerships”) as of December 31, 2014 was as follows:
	Name	Partner		Company’s		Company’s		Date Acquired
				Ownership		Economic
				Interest		Interest
	PREI I LLC (1)	PREI		20%		20%		April 4, 2007
	PREI II LLC	PREI		20%		20%		April 4, 2007
	McKellar Court (2)	Quidel Corporation		22%		22%		September 30, 2004
	BioPark Fremont	RPC Poppleton, LLC		50%		50%		May 31, 2013
	-1	PREI I LLC owns two properties in Cambridge, Massachusetts. At December 31, 2014, there were $139.0 million in outstanding borrowings on a secured loan facility held by a wholly-owned subsidiary of PREI I LLC, with a contractual interest rate of 2.21% (including the applicable credit spread) and a maturity date of August 13, 2015 (with an option to extend the maturity date to August 13, 2016 at its discretion after satisfying certain conditions and paying an extension fee).
	-2	The Company’s investment in the McKellar Court partnership (maximum exposure to losses) was approximately $11.8 million at December 31, 2014. The Company’s economic interest in the McKellar Court partnership entitles it to 75% of the extraordinary cash flows after repayment of the partners’ capital contributions and 22% of the operating cash flows.
Summary of Selected Balance Sheet Information	The condensed combined balance sheets for all of the Company’s unconsolidated partnerships were as follows (in thousands):
		December 31,				December 31,
		2014				2013
	Assets:
	Investments in real estate, net	$	267,007			$	262,753
	Cash and cash equivalents (including restricted cash)	6,057				3,855
	Other assets	11,599				5,301
	Total assets	$	284,663			$	271,909
	Liabilities and members’ equity:
	Mortgage notes payable and secured loan	$	152,056			$	151,968
	Other liabilities	9,020				12,102
	Members’ equity	123,587				107,839
	Total liabilities and members equity	$	284,663			$	271,909
	Company’s net investment in unconsolidated partnerships	$	35,291			$	32,137
Schedule of Selected Income Statement Information	The selected data and results of operations for the unconsolidated partnerships were as follows (in thousands):
			Years Ended December 31,
			2014				2013			2012
	Total revenues		$	35,495			$	12,930		$	8,823
	Total expenses		(36,013		)		(21,589		)	(19,939		)
	Net loss		$	(518	)		$	(8,659	)	$	(11,116	)
	Company’s equity in net income / (loss) of unconsolidated partnerships		$	745			$	(905	)	$	(1,389	)
	Fees earned by the Company (1)		$	999			$	260		$	90
	-1	The Company acts as the operating member or partner, as applicable, and day-to-day manager for the partnerships. The Company is entitled to receive fees for providing construction and development services (as applicable) and management services to the PREI joint ventures, which are reflected in tenant recoveries and other income in the consolidated statements of operations.

Derivatives_and_Other_Financia1

Derivatives and Other Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Derivative Instruments
												Fair-Value(1)
		Notional Amount										December 31,			December 31,
						Strike Rate			Effective Date	Expiration Date		2014			2013
	Interest rate swaps	$	200,000			1.163	%		March 30, 2012	March 30, 2017		$	(1,448	)	$	(1,876	)
	Interest rate swaps	200,000				0.701	%		October 1, 2013	October 1, 2016		(186		)	(288		)
	Interest rate swaps(2)	77,865				0.731	%		August 2, 2012	March 30, 2017		63			1,545
	Interest rate swaps(2)	77,865				0.7425	%		August 2, 2012	March 30, 2017		45			1,519
	Total interest rate swaps	$	555,730									$	(1,526	)	$	900
	-1	Fair-value of derivative instruments does not include any related accrued interest payable, which is included in accrued expenses on the accompanying consolidated balance sheets. Derivative valuations are classified in Level 2 of the fair-value hierarchy. Assets are included in other assets and liabilities are included in accounts payable, accrued expenses and other liabilities on the accompanying consolidated balance sheets.
	-2	Translation to U.S. dollars is based on exchange rates of $1.56 to £1.00 and $1.65 to £1.00 at December 31, 2014 and December 31, 2013, respectively.
Summary of Derivative Instruments, Effect on OCI	The following is a summary of the amount of gain / (loss) recognized in other comprehensive income related to the derivative instruments (in thousands):
			Year Ended
			December 31,
			2014				2013			2012
	Amount of (loss) / gain recognized in other comprehensive income (effective portion):
	Cash flow hedges
	Interest rate swaps		$	(6,625	)		$	3,497		$	(6,863	)
	Amount of loss reclassified from accumulated other comprehensive loss to income (effective portion):
	Cash flow hedges
	Interest rate swaps (1)		$	(3,537	)		$	(2,619	)	$	(1,578	)
	Forward starting swaps (2)		(6,722		)		(6,832		)	(6,933		)
	Total interest rate swaps		$	(10,259	)		$	(9,451	)	$	(8,511	)
	Amount of (loss) / gain recognized in income (ineffective portion and amount excluded from effectiveness testing):
	Other derivative instruments		(23		)		416			(9		)
	Total (loss) / gain on derivative instruments		$	(23	)		$	416		$	(9	)
	-1	Amount represents payments made to swap counterparties for the effective portion of interest rate swaps that were recognized as an increase to interest expense for the periods presented (the amount was recorded as an increase and corresponding decrease to accumulated other comprehensive loss in the same accounting period).
	-2	Amount represents reclassifications of deferred interest costs from accumulated other comprehensive loss to interest expense related to the Company’s previously settled forward starting swaps.

FairValue_of_Financial_Instrum1

Fair-Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair-Value and Carrying Value of the Company's Financial Instruments	At December 31, 2014 and December 31, 2013, the aggregate fair-value and the carrying value of the Company’s financial instruments were as follows (in thousands):
		December 31, 2014				December 31, 2013
		Fair-Value (1)		Carrying Value		Fair-Value (1)			Carrying Value
	Mortgage notes payable, net	$	502,115	$	496,757	$	730,394		$	709,324
	Exchangeable Senior Notes	134,619		95,678		202,626			180,000
	Notes due 2016, net	411,600		399,304		417,040			398,787
	Noted due 2019, net	398,280		397,873		—			—
	Notes due 2020, net	283,250		248,450		275,600			248,210
	Notes due 2022, net	258,250		248,275		240,400			248,086
	Term Loan due 2017 - U.S. dollar	244,945		243,596		244,751			243,596
	Term Loan due 2017 - GBP (2)	156,589		155,730		165,969			165,190
	Term Loan due 2018	350,557		350,000		350,000			350,000
	Unsecured line of credit	83,866		84,000		128,000			128,000
	Derivative instruments (3)	1,132		1,132		(1,316		)	(1,316		)
	Available-for-sale securities	58,621		58,621		19,566			19,566
	-1	Fair-values of debt and derivative instruments are classified in Level 2 of the fair-value hierarchy. Fair-value of available-for-sale securities are classified in Level 1 of the fair-value hierarchy.
	-2	The principal balance represents the U.S. dollar amount based on the exchange rate of $1.56 to £1.00 and $1.65 to £1.00 at December 31, 2014 and December 31, 2013, respectively.
	-3	The Company’s derivative instruments are reflected in other assets and in accounts payable, accrued expenses and other liabilities on the accompanying consolidated balance sheets based on their respective balances (see Note 9).

Acquisitions_Tables

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2014
Business Acquisition
Schedule of Purchase Price Allocation	Acquisitions
	The Company acquired the following properties during the year ended December 31, 2014. The table below reflects the preliminary purchase price allocation for these acquisitions (in thousands).
	Property		Acquisition Date	Investments in Real Estate		Above Market Lease		Below Market Lease			Below Market Ground Lease		In-Place Lease		Debt Premium			Acquisition Date Fair-Value
	100 College Street (1)		April 4, 2014	$	63,361	$	—	$	—		$	—	$	33,239	$	—		$	96,600
	300 George Street (2)		April 4, 2014	107,021		63		(3,926		)	—		17,808		(3,966		)	117,000
	430 Cambridge Science Park (3)		May 15, 2014	—		—		—			3,836		—		—			3,836
	Wake 60 (4)		December 17, 2014	3,525		—		—			—		—		—			3,525
	Total			$	173,907	$	63	$	(3,926	)	$	3,836	$	51,047	$	(3,966	)	$220,961
	Weighted average intangible amortization life (in months)					21		143			1500		159		135
	-1	The property is currently under construction in New Haven Connecticut and is expected to be a 510,419 square foot laboratory and office building. The total project investment was estimated to be approximately $191 million at acquisition, comprised of (a) approximately $89 million in cash, assumption of mortgage notes payable and a noncontrolling interest of Winstanley Enterprises LLC and affiliates, which will also continue to provide construction and property management services for the property, and (b) approximately $102 million of estimated remaining construction costs from the date of acquisition. As of April 4, 2014, Winstanley Enterprises, LLC and affiliates retained an approximate 25% noncontrolling interest. On June 3, 2014, Winstanley Enterprises LLC and its affiliates' noncontrolling interest was reduced to approximately 7% as a result of additional investments by the Company. Upon completion of construction and repayment of the related construction loan, the Company expects Winstanley Enterprises LLC and its affiliates' noncontrolling interest in the property to be reduced to approximately 2.5%.
	-2	The property is a 518,940 square foot laboratory and office building in New Haven, Connecticut. The total consideration also included the assumption of $46.3 million of mortgage notes payable and a 7% noncontrolling interest of Winstanley Enterprises LLC, which will also continue to provide property management services for the property.
	-3	The property is currently under construction in Cambridge, United Kingdom and is expected to be a 42,410 square foot laboratory and office building. The total project investment at acquisition was expected to be approximately $22.7 million.
	-4	The property is currently under construction in Winston-Salem, North Carolina and is expected to be a 283,250 square foot laboratory and office building.
	Revenues of approximately $13.9 million and net loss of $307,000 associated with properties acquired in 2014 listed above are included in the consolidated statements of operations for the year ended December 31, 2014 for both the Parent Company and the Operating Partnership.

Discontinued_Operations_Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	The table below reflects the details of the property and the exchange (in thousands):
	Property		Date of Sale		Original Acquisition Date	Sales Price (1)		Impairment loss
	Forbes Boulevard		April 27, 2012		September 5, 2007	$	28,000	$	(4,552	)
	-1	The sales price was equal to the fair-value of the office property received as consideration in the exchange with the independent third party.
	The results of operations of the Forbes Boulevard property are reported as discontinued operations for all periods presented in the accompanying consolidated financial statements. The following table summarizes the revenue and expense components that comprise income / (loss) from discontinued operations (in thousands):
			Year Ended December 31, 2012
	Total revenues		$	454
	Total expenses		272
	Income from discontinued operations before impairment loss		182
	Impairment loss		(4,552		)
	Loss from discontinued operations		$	(4,370	)

Incentive_Award_Plan_Incentive1

Incentive Award Plan Incentive Award Plan (Tables)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Summary of Unvested Restricted Stock and LTIP Units [Abstract]	A summary of the Company’s unvested restricted stock and LTIP units is presented below:
		Unvested Restricted Shares/LTIP Units		Weighted Average Grant-Date Fair-Value
	Balance at December 31, 2011	1,721,062		$	16.09
	Granted	395,350		18.46
	Vested	(520,258	)	15.17
	Forfeited	(35,642	)	15.97
	Balance at December 31, 2012	1,560,512		17
	Granted	657,106		20.33
	Vested	(665,808	)	15.91
	Forfeited	(39,805	)	18.15
	Balance at December 31, 2013	1,512,005		18.91
	Granted	587,662		18.94
	Vested	(602,228	)	18.18
	Forfeited	(20,427	)	19.83
	Balance at December 31, 2014	1,477,012		$	19.1
Incentive Award Plan Selected Data [Line Items]	Incentive Award Plan
	The Company has adopted the 2013 Amendment and Restatement of the BioMed Realty Trust, Inc. and BioMed Realty, L.P. 2004 Incentive Award Plan (the “Plan”). The Plan provides for grants to directors, employees and consultants of the Company and the Operating Partnership (and their respective subsidiaries) of stock options, restricted stock, LTIP units, stock appreciation rights, dividend equivalents, and other incentive awards. The Company has reserved 10,740,000 shares of common stock for issuance pursuant to the Plan, subject to adjustments as set forth in the Plan. As of December 31, 2014, 6,534,731 shares of common stock or awards convertible into or exchangeable for common stock remained available for future issuance under the Plan. Each LTIP unit and each Performance Unit issued will count as one share of common stock for purposes of calculating the limit on shares that may be issued. Compensation cost for these incentive awards is measured based on the fair-value of the award on the grant date (fair-value is calculated based on the closing price of the Company’s common stock on the date of grant) and is recognized as expense over the respective vesting period, which for restricted stock awards and LTIP units is generally four to five years. Fully vested incentive awards may be settled for either cash or stock depending on the Company’s election and the type of award granted. Participants are entitled to cash dividends and may vote such awarded shares, but the sale or transfer of such shares is limited during the restricted or vesting period. The restricted stock grants may only be settled for stock whereas the LTIP units may be redeemed for either cash or common stock, at the Company’s election.
	The Parent Company has awarded Performance Units to certain of its executive officers, which represent the maximum number of Performance Units that may vest. Each Performance Unit represents a contingent right to receive one share of the Parent Company’s common stock if vesting conditions are satisfied. Performance Units vest at the end of designated time periods (each, a “Performance Period”) based upon the Parent Company’s total stockholder return relative to its peer group (the “Market Conditions”). The grant date fair-value of the Performance Units was estimated using a Monte Carlo simulation which considered the likelihood of achieving the Market Conditions. The Monte Carlo simulation uses a statistical formula underlying the Black-Scholes and binomial formulas, and such simulation was run approximately 100,000 times. For each simulation, the value of the payoff was calculated at the end of the respective Performance Period and was then discounted to the grant date at a risk-free interest rate. The expected value of the Performance Units on the grant date was determined by simulating the total shareholder return for the Company and the peer group considering the stock price variance for each of the peer group companies, compared to each other and the Company's stock estimating the rank of the Company's stock. The valuation was performed in a risk-neutral framework, so no assumption was made with respect to an equity risk premium. Other significant assumptions used in the valuation included an expected term of 24 and 36 months, an average risk-free interest rate of 0.49%, and an average dividend yield of 4.64%. No dividends will be paid or accrued on the Performance Units, and shares of the Parent Company’s common stock will not be issued until vesting of the Performance Units occurs.
	A summary of the Company’s unvested restricted stock and LTIP units is presented below:
		Unvested Restricted Shares/LTIP Units		Weighted Average Grant-Date Fair-Value
	Balance at December 31, 2011	1,721,062		$	16.09
	Granted	395,350		18.46
	Vested	(520,258	)	15.17
	Forfeited	(35,642	)	15.97
	Balance at December 31, 2012	1,560,512		17
	Granted	657,106		20.33
	Vested	(665,808	)	15.91
	Forfeited	(39,805	)	18.15
	Balance at December 31, 2013	1,512,005		18.91
	Granted	587,662		18.94
	Vested	(602,228	)	18.18
	Forfeited	(20,427	)	19.83
	Balance at December 31, 2014	1,477,012		$	19.1
	Selected data of the Company’s incentive award plan is presented below (in thousands, except share and period amounts):
		Years Ended December 31,
		2014			2013		2012
	Aggregate value of restricted stock/LTIP Units granted	$	11,181		$	13,234	$	7,300
	Aggregate value of Performance Units granted	$	4,186		$	4,973	$	3,329
	Fair-value of stock/LTIP Units vested	$	11,782		$	13,321	$	9,502
	Stock-based compensation expense recognized in general and administrative expenses and rental operations expense - restricted stock/LTIP Units	$	12,188		$	10,134	$	9,556
	Stock-based compensation expense recognized in general and administrative expenses - Performance Units	$	3,574		$	2,445	$	1,974
	Shares surrendered to the Company and retired in lieu of cash payments for taxes due on the vesting of restricted stock	225,906			253,671		178,915
	Data at period end:
	Total compensation to be expensed related to unvested awards in future periods - restricted stock	$	16,926
	Weighted-average expense period (in years) - restricted stock	2.4
	Total compensation to be expensed related to unvested awards in future periods - Performance Units	$	3,179
	Weighted-average expense period (in years) - Performance Units	1.8

Quarterly_Financial_Informatio2

Quarterly Financial Information of the Parent Company Quarterly Financial Information of the Parent Company (Tables) (Parent Company)	12 Months Ended
	Dec. 31, 2014
Parent Company
Quarterly Financial Information Disclosure [Line Items]
Schedule of Quarterly Financial Information [Table Text Block]	The Company’s selected quarterly information for the years ended December 31, 2014 and 2013 (in thousands, except per share data) was as follows.
		2014 Quarter Ended(1)
		31-Dec			30-Sep			30-Jun			31-Mar
	Total revenues	$	165,656		$	168,916		$	171,161		$	168,876
	Gain on sale of real estate	136,609			—			—			—
	Net income	144,627			16,976			19,098			20,767
	Net income attributable to noncontrolling interests	(4,278		)	(1,016		)	(462		)	(1,934		)
	Net income available to common stockholders	$	140,349		$	15,960		$	18,636		$	18,833
	Income from continuing operations per share available to common stockholders-basic	$	0.71		$	0.08		$	0.1		$	0.1
	Income from continuing operations per share available to common stockholders-diluted	$	0.7		$	0.08		$	0.1		$	0.1
	Net income per share available to common stockholders-basic	$	0.71		$	0.08		$	0.1		$	0.1
	Net income per share available to common stockholders-diluted	$	0.7		$	0.08		$	0.1		$	0.1
		2013 Quarter Ended(1)
		31-Dec			30-Sep			30-Jun			31-Mar
	Total revenues	$	157,993		$	159,232		$	159,639		$	160,450
	Net income	10,576			4,136			15,037			17,458
	Net (income) / loss attributable to noncontrolling interests	(297		)	111			(234		)	(146		)
	Preferred stock dividends	—			—			—			(2,393		)
	Net income available to common stockholders	$	10,279		$	4,247		$	14,803		$	8,388
	Income from continuing operations per share available to common stockholders - basic and diluted	$	0.05		$	0.02		$	0.08		$	0.05
	Net income per share available to common stockholders - basic and diluted	$	0.05		$	0.02		$	0.08		$	0.05
	-1	The sum of quarterly financial data may vary from the annual data due to rounding.

Quarterly_Financial_Informatio3

Quarterly Financial Information of the Operating Partnership Quarterly Financial Information of the Operating Partnership (Tables) (BIOMED REALTY, L.P.)	12 Months Ended
	Dec. 31, 2014
BIOMED REALTY, L.P.
Quarterly Financial Information Disclosure [Line Items]
Schedule of Quarterly Financial Information [Table Text Block]	The Company’s selected quarterly information for the years ended December 31, 2014 and 2013 (in thousands, except per share data) was as follows.
		2014 Quarter Ended(1)
		31-Dec			30-Sep			30-Jun		31-Mar
	Total revenues	$	165,656		$	168,916		$	171,161	$	168,876
	Gain on sale of real estate	136,609			—			—		—
	Net income	144,627			16,976			19,098		20,767
	Net (income) / loss attributable to noncontrolling interests	(496		)	(587		)	52		(1,413		)
	Net income available to unit holders	$	144,131		$	16,389		$	19,150	$	19,354
	Income from continuing operations per unit available to unit holders-basic	$	0.71		$	0.08		$	0.1	$	0.1
	Income from continuing operations per unit available to unit holders-diluted	$	0.7		$	0.08		$	0.1	$	0.1
	Net income per unit available to unit holders-basic	$	0.71		$	0.08		$	0.1	$	0.1
	Net income per unit available to unit holders-diluted	$	0.7		$	0.08		$	0.1	$	0.1
		2013 Quarter Ended(1)
		31-Dec			30-Sep			30-Jun		31-Mar
	Total revenues	$	157,993		$	159,232		$	159,639	$	160,450
	Net income	10,576			4,136			15,037		17,458
	Net (income) / loss attributable to noncontrolling interests	(12		)	229			29		8
	Preferred unit distributions	—			—			—		(2,393		)
	Net income available to unit holders	$	10,564		$	4,365		$	15,066	$	8,542
	Income from continuing operations per unit available to unit holders - basic and diluted	$	0.05		$	0.02		$	0.08	$	0.05
	Net income per unit available to unit holders - basic and diluted	$	0.05		$	0.02		$	0.08	$	0.05
	-1	The sum of quarterly financial data may vary from the annual data due to rounding.

Organization_of_the_Parent_Com1

Organization of the Parent Company and Description of Business (Details)	Dec. 31, 2014	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements
Equity Method Investment, Ownership Percentage	100.00%	100.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	2.60%
Parent Company
Organization, Consolidation and Presentation of Financial Statements
Equity Method Investment, Ownership Percentage	97.40%	97.30%

Basis_of_Presentation_and_Summ3

Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Deferred Costs and Other Assets	$5,200,000								$4,300,000								$5,200,000	$4,300,000
Tax credits, net of costs and estimated put paments																	48,800,000	34,400,000
Tax Credits Delivered																	-55,500,000	-22,400,000
Provision for Doubtful Accounts																	900,000	900,000	1,700,000
Real Estate Inventory, Capitalized Interest Costs	-21,900,000								-14,200,000								-21,900,000	-14,200,000	-8,600,000
Real Estate Investment Property, Net	5,416,575,000								5,217,902,000								5,416,575,000	5,217,902,000
Number of Variable Interest Entities that the Company is the Primary Beneficiary																	6	5
Fair Value																			28,000,000	[1]
Impairment of Long-Lived Assets to be Disposed of																			4,552,000
Reclassification Of Other Than Temporary Unrealized Loss From Accumulated Other Comprehensive Income To General And Administrative Expense																	-2,000,000	-2,800,000
Extension options																	1 year
Investment In Construction Loan																		151,800,000
Lease Termination Revenue																	12,600,000	42,800,000
Capitalized Payroll	-4,400,000								-3,600,000								-4,400,000	-3,600,000	-2,000,000
Finite-Lived Intangible Assets, Net	219,713,000								198,067,000								219,713,000	198,067,000
Allowance for Doubtful Accounts Receivable	-2,400,000								-2,300,000								-2,400,000	-2,300,000	-4,200,000
Foreign
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Revenue from properties outside the United States, net																	20,200,000	18,200,000	10,300,000
Percentage of Company's total revenue																	3.00%	2.90%	2.00%
Real Estate Investment Property, Net	200,200,000								190,200,000								200,200,000	190,200,000	188,800,000
Boston Development Project
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
BioMed Realty Trust Interest in Construction Loan																	255,000,000
Construction Loan																	355,000,000
Square Footage of Real Estate Property	1,100,000																1,100,000
Percent Leased	95.00%																95.00%
Investment In Construction Loan																	191,200,000
Other revenue																	7,500,000
Science Center at Oyster Point
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Real Estate Investment Property, Net	101,866,000																101,866,000
Lease Termination Revenue																	46,500,000
320 Bent Street
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Real Estate Investment Property, Net	87,859,000																87,859,000
Lease Termination Revenue																	8,700,000
Deferred Leasing and Other Direct Costs [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Net	72,633,000								60,501,000								72,633,000	60,501,000
Deferred Leasing Costs [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	37,121,000																37,121,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	29,029,000																29,029,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	26,596,000																26,596,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	22,348,000																22,348,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	17,571,000																17,571,000
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	87,048,000																87,048,000
Finite-Lived Intangible Assets, Net	219,713,000																219,713,000
Historic and New Market Tax Credits [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Syndicated Historic Tax Credits and New Market Tax Credits																	10	9
New Market Tax Credits [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Percentage Of Tax Credit Recapture																	100.00%
Historical Tax Credit Recapture Period																	1 year
Historic tax credit [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Percentage Of Qualified Investments																	39.00%
Percentage Of Tax Credit Recapture																	20.00%
Maximum [Member] | Deferred Leasing and Other Direct Costs [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Remaining Amortization Period																	20 years
Parent Company
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Proceeds from Sale of Property Held-for-sale																	317,187,000
Gain (Loss) on Sale of Properties	136,609,000		0		0		0										136,609,000	0	0
Provision for Doubtful Accounts																	900,000	931,000	1,656,000
Revenue from properties outside the United States, net	165,656,000	[2]	168,916,000	[2]	171,161,000	[2]	168,876,000	[2]	157,993,000	[2]	159,232,000	[2]	159,639,000	[2]	160,450,000	[2]	674,609,000	637,314,000	518,167,000
Real Estate Investment Property, Net	5,416,575,000								5,217,902,000								5,416,575,000	5,217,902,000
Other revenue																	$26,454,000	$49,700,000	$4,746,000
[1]	The sales price was equal to the fair-value of the office property received as consideration in the exchange with the independent third party.
[2]	The sum of quarterly financial data may vary from the annual data due to rounding.

Basis_of_Presentation_and_Summ4

Basis of Presentation and Summary of Significant Accounting Policies (Selected Financial Data of the VIEs) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]
Variable Interest Entity Carrying Amount Of Collateralized Investment In Real Estate Net	$433,842	$336,832
Variable Interest Entity, Consolidated, Carrying Amount, Assets	493,066	375,443
Total Debt	189,848	143,067
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	203,529	154,953
Wexford Merger [Member]
Accounting Policies [Abstract]
Variable Interest Entity Carrying Amount Of Collateralized Investment In Real Estate Net	2,507	177,901
Variable Interest Entity, Consolidated, Carrying Amount, Assets	24,478	198,968
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$7,467	$60,197

Basis_of_Presentation_and_Summ5

Basis of Presentation and Summary of Significant Accounting Policies (Investments in Real Estate, Net) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]
Land	$704,958	$713,955
Land Under Development	151,242	119,325
Buildings and Improvements	4,877,135	4,854,175
Construction in Progress	629,679	316,025
Real Estate Investment Property, at Cost	6,363,014	6,003,480
Accumulated Depreciation	-946,439	-785,578
Real Estate Investment Property, Net	$5,416,575	$5,217,902

Basis_of_Presentation_and_Summ6

Basis of Presentation and Summary of Significant Accounting Policies (Deferred Leasing Costs, Net) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred Leasing Costs
Finite-Lived Intangible Assets, Gross	$552,480	$482,696
Finite-Lived Intangible Assets, Accumulated Amortization	-332,767	-284,629
Finite-Lived Intangible Assets, Net	219,713	198,067
Leases, Acquired-in-Place [Member]
Deferred Leasing Costs
Finite-Lived Intangible Assets, Gross	415,389	365,753
Finite-Lived Intangible Assets, Accumulated Amortization	-271,782	-233,935
Finite-Lived Intangible Assets, Net	143,607	131,818
Acquired Management Agreements
Deferred Leasing Costs
Finite-Lived Intangible Assets, Gross	25,801	25,801
Finite-Lived Intangible Assets, Accumulated Amortization	-22,328	-20,053
Finite-Lived Intangible Assets, Net	3,473	5,748
Deferred Leasing and Other Direct Costs [Member]
Deferred Leasing Costs
Finite-Lived Intangible Assets, Gross	111,290	91,142
Finite-Lived Intangible Assets, Accumulated Amortization	-38,657	-30,641
Finite-Lived Intangible Assets, Net	$72,633	$60,501

Basis_of_Presentation_and_Summ7

Basis of Presentation and Summary of Significant Accounting Policies (Deferred Leasing Costs-Estimated Amortization) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Net	$219,713	$198,067
Deferred Leasing Costs [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	37,121
Finite-Lived Intangible Assets, Amortization Expense, Year Two	29,029
Finite-Lived Intangible Assets, Amortization Expense, Year Three	26,596
Finite-Lived Intangible Assets, Amortization Expense, Year Four	22,348
Finite-Lived Intangible Assets, Amortization Expense, Year Five	17,571
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	87,048
Finite-Lived Intangible Assets, Net	$219,713

Basis_of_Presentation_and_Summ8

Basis of Presentation and Summary of Significant Accounting Policies (Impact of Straight Line Rent Revenue, Acquired above-market lease revenue, Acquired below-market lease revenue and Lease incentive revenue) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Straight-line rent revenue	$13,197	$23,136	$23,288
Acquired Above Market Lease Revenue	-4,647	-11,913	-9,977
Acquired Below Market Lease Revenue	6,061	4,325	1,684
Lease Incentive Revenue	-2,674	-2,295	-2,969
Lease Revenue Net	$11,937	$13,253	$12,026

Basis_of_Presentation_and_Summ9

Basis of Presentation and Summary of Significant Accounting Policies (Estimated Minimum Rents) (Details) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Accounting Policies [Abstract]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$451,321
Operating Leases, Future Minimum Payments, Due in Two Years	450,748
Operating Leases, Future Minimum Payments, Due in Three Years	433,538
Operating Leases, Future Minimum Payments, Due in Four Years	377,925
Operating Leases, Future Minimum Payments, Due in Five Years	336,180
Operating Leases, Future Minimum Payments, Due Thereafter	2,300,692
Operating Leases, Future Minimum Payments Due	$4,350,404

Recovered_Sheet1

Basis of Presentation and Summary of Significant Accounting Policies (Revenue Recognition-Estimated Amortization) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Net	$219,713	$198,067
Acquired Above Market Leases [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	-1,895
Finite-Lived Intangible Assets, Amortization Expense, Year Two	-1,307
Finite-Lived Intangible Assets, Amortization Expense, Year Three	-1,179
Finite-Lived Intangible Assets, Amortization Expense, Year Four	-1,132
Finite-Lived Intangible Assets, Amortization Expense, Year Five	-972
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	-4,722
Finite-Lived Intangible Assets, Net	-11,207
Acquired Below Market Leases [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	4,042
Finite-Lived Intangible Assets, Amortization Expense, Year Two	3,782
Finite-Lived Intangible Assets, Amortization Expense, Year Three	3,690
Finite-Lived Intangible Assets, Amortization Expense, Year Four	3,656
Finite-Lived Intangible Assets, Amortization Expense, Year Five	3,150
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	17,478
Finite-Lived Intangible Assets, Net	35,798
Lease Incentives [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	-3,951
Finite-Lived Intangible Assets, Amortization Expense, Year Two	-3,863
Finite-Lived Intangible Assets, Amortization Expense, Year Three	-3,420
Finite-Lived Intangible Assets, Amortization Expense, Year Four	-1,615
Finite-Lived Intangible Assets, Amortization Expense, Year Five	-1,456
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	-10,109
Finite-Lived Intangible Assets, Net	($24,414)

Recovered_Sheet2

Basis of Presentation and Summary of Significant Accounting Policies (Investments) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]
Available-for-sale securities, historical cost	$10,280		$8,543
Unrealized gain, net	48,341		11,023
Available-for-sale securities, fair-value	58,621	[1]	19,566	[1]
Privately-held securities, cost basis	43,428		18,485
Total equity securities	$102,049		$38,051
[1]	Determination of fair-value is classified as Level 1 in the fair-value hierarchy based on the use of quoted prices in active markets.

Recovered_Sheet3

Basis of Presentation and Summary of Significant Accounting Policies (Income Tax Treatment for Dividends) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common Stock, Dividends, Per Share, Cash Paid	$1.30	$0.94	$0.85
Percentage Of Common Stock Dividend	100.00%	100.00%	100.00%
Preferred Stock, Dividends, Per Share, Cash Paid		$0.76	$1.84
Percentage Of Preferred Stock Dividend		100.00%	100.00%
Ordinary Income [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common Stock, Dividends, Per Share, Cash Paid	$0	$0.94	$0.63
Percentage Of Common Stock Dividend	38.46%	100.00%	74.12%
Preferred Stock, Dividends, Per Share, Cash Paid		$0.76	$1.84
Percentage Of Preferred Stock Dividend		100.00%	100.00%
Capital Gains [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common Stock, Dividends, Per Share, Cash Paid	$0.80	$0	$0
Percentage Of Common Stock Dividend	61.54%
Preferred Stock, Dividends, Per Share, Cash Paid	$0	$0	$0
Percentage Of Preferred Stock Dividend	0.00%	0.00%	0.00%
Return On Capital [Member]
Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Common Stock, Dividends, Per Share, Cash Paid			$0.22
Percentage Of Common Stock Dividend			25.88%
Preferred Stock, Dividends, Per Share, Cash Paid	$0	$0	$0
Percentage Of Preferred Stock Dividend	0.00%	0.00%	0.00%

Recovered_Sheet4

Basis of Presentation and Summary of Significant Accounting Policies Selected Financial Data of the VIEs, Wexford (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Variable Interest Entity Carrying Amount Of Collateralized Investment In Real Estate Net	$433,842	$336,832
Variable Interest Entity, Consolidated, Carrying Amount, Assets	493,066	375,443
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	203,529	154,953
Wexford Merger [Member]
Variable Interest Entity Carrying Amount Of Collateralized Investment In Real Estate Net	2,507	177,901
Variable Interest Entity, Consolidated, Carrying Amount, Assets	24,478	198,968
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$7,467	$60,197

Equity_of_the_Parent_Company_N

Equity of the Parent Company (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Dec. 31, 2011
Equity of the Parent Company
Performance units forfeited during the period	-20,427	-39,805	-35,642
Performance units	587,662	657,106	395,350
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	602,228	665,808	520,258
Parent Company
Equity of the Parent Company
Shares surrendered to the Company and retired in lieu of cash payments for taxes due on the vesting of restricted stock	-218,663
Shares forfeited during the period	13,114
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	4.2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	2.6
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	2 years
Performance units forfeited during the period	-7,313
Noncontrolling Interest Redemption Value	116.9
Average Closing Price Per Common Share				$21.62
Noncontrolling Interest Redemption Value Calculation Days				10 days
Parent Company | Common Stock
Equity of the Parent Company
Common Stock, Shares Outstanding	197,442,432	192,115,002	154,327,818		154,101,482
Parent Company | Operating Partnership Units and LTIP Units
Equity of the Parent Company
Partnership Units, Shares Outstanding	5,083,400
LTIP Units, Shares Outstanding	322,074
Parent Company | Restricted Stock Issued to Employees
Equity of the Parent Company
Restricted Stock Awards Issued	565,107
Parent Company | Restricted Stock Issued to Board Members
Equity of the Parent Company
Restricted Stock Awards Issued	22,555
Performance Shares 2012 [Member] | Parent Company
Equity of the Parent Company
Shares surrendered to the Company and retired in lieu of cash payments for taxes due on the vesting of restricted stock	-7,243
Performance units forfeited during the period	-116,072
Performance units			136,296
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	20,224
Performance Shares 2013 [Member] | Parent Company
Equity of the Parent Company
Shares surrendered to the Company and retired in lieu of cash payments for taxes due on the vesting of restricted stock	-5,504
Performance units forfeited during the period	-189,929
Performance units		203,144
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	13,215
Performance Shares | Parent Company
Equity of the Parent Company
Performance units	494,410

Equity_of_the_Parent_Company_D

Equity of the Parent Company (Dividends and Distributions) (Details) (Common Stock And Op Units [Member], USD $)	3 Months Ended				12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014
Common Stock And Op Units [Member]
Equity of the Parent Company
Common Stock, Dividends, Per Share, Declared	$0.26	$0.25	$0.25	$0.25	$0.30
Payment of Special Dividend					$60,854
Dividends Payable, Date to be Paid	15-Jan-15	15-Oct-14	15-Jul-14	15-Apr-14
Payments of Dividends	$52,740	$50,714	$49,483	$49,479	$263,270
Dividends Payable, Date Declared	15-Dec-14	15-Sep-14	16-Jun-14	17-Mar-14

Equity_of_the_Parent_Company_E

Equity of the Parent Company Equity of the Parent Company (Changes in Accumulated Other Comprehensive Loss by Component) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), Net of Tax	$39,313
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	-8,604
Parent Company
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss, net	-2,214		-32,923
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	-38,376
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	937	[1]
Other Comprehensive Income (Loss), Net of Tax	39,313		24,250	5,517
Accumulated Translation Adjustment [Member] | Parent Company
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss, net	2,309		3,905
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	1,639
Other Comprehensive Income (Loss), Net of Tax	-1,639
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	43
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Parent Company
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss, net	37,705		8,938
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	-46,640
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	9,322
Other Comprehensive Income (Loss), Net of Tax	37,318
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	-8,551
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Parent Company
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss, net	-42,228		-45,766
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	10,259
Other Comprehensive Income (Loss), Net of Tax	3,634
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	-96
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Interest Rate Swaps | Parent Company
Accumulated Other Comprehensive Income Loss [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	($6,625)
[1]	Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of operations. See Note 9 for further information.

Equity_of_the_Parent_Company_V

Equity of the Parent Company (Vested Ownership Interests) (Details)	Dec. 31, 2014	Dec. 31, 2013
Equity of the Parent Company
Operating Partnership Units and LTIP Units	201,304,571	195,959,961
Equity Method Investment, Ownership Percentage	100.00%	100.00%
Parent Company
Equity of the Parent Company
Operating Partnership Units and LTIP Units	196,031,538	190,676,428
Equity Method Investment, Ownership Percentage	97.40%	97.30%
Operating Partnership and LTIP Units Held By Employees and Related Parties
Equity of the Parent Company
Operating Partnership Units and LTIP Units	2,645,888	2,656,388
Equity Method Investment, Ownership Percentage	1.30%	1.40%
Operating Partnership and LTIP Units Held By Third Parties
Equity of the Parent Company
Operating Partnership Units and LTIP Units	2,627,145	2,627,145
Equity Method Investment, Ownership Percentage	1.30%	1.30%

Capital_of_the_Operating_Partn2

Capital of the Operating Partnership (Narrative) (Details) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Capital of the Operating Partnership [Line Items]
Equity Method Investment, Ownership Percentage		100.00%	100.00%
BIOMED REALTY, L.P.
Capital of the Operating Partnership [Line Items]
Partners' Capital Account, Units		202,525,832
LTIP Units, Shares Outstanding		322,074
Parent Company
Capital of the Operating Partnership [Line Items]
Noncontrolling Interest Redemption Value		116.9
Average Closing Price Per Common Share	$21.62
Noncontrolling Interest Redemption Value Calculation Days	10 days
Parent Company
Capital of the Operating Partnership [Line Items]
Equity Method Investment, Ownership Percentage		97.40%	97.30%

Capital_of_the_Operating_Partn3

Capital of the Operating Partnership Capital of the Operating Partnership (Changes in Accumulated Other Comprehensive Loss by Component) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Capital of the Operating Partnership [Line Items]
Other Comprehensive Income (Loss), Net of Tax	$39,313
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	-8,604
BIOMED REALTY, L.P.
Capital of the Operating Partnership [Line Items]
Accumulated other comprehensive loss, net	878		-30,663
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	38,376
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	937	[1]
Other Comprehensive Income (Loss), Net of Tax	39,313		24,250	5,517
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	-7,772
Accumulated Translation Adjustment [Member] | BIOMED REALTY, L.P.
Capital of the Operating Partnership [Line Items]
Accumulated other comprehensive loss, net	2,367		4,006
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	-1,639
Other Comprehensive Income (Loss), Net of Tax	-1,639
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	0
Accumulated Net Unrealized Investment Gain (Loss) [Member] | BIOMED REALTY, L.P.
Capital of the Operating Partnership [Line Items]
Accumulated other comprehensive loss, net	38,732		9,186
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	46,640
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	-9,322
Other Comprehensive Income (Loss), Net of Tax	37,318
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	-7,772
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | BIOMED REALTY, L.P.
Capital of the Operating Partnership [Line Items]
Accumulated other comprehensive loss, net	-40,221		-43,855
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	-6,625
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	10,259
Other Comprehensive Income (Loss), Net of Tax	3,634
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	$0
[1]	Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of operations. See Note 9 for further information.

Debt_Debt_Narrative_Details

Debt Debt (Narrative) (Details)

Dec. 31, 2014

Sep. 26, 2013

Dec. 31, 2014

Sep. 30, 2014

Dec. 31, 2014

Sep. 30, 2014

Dec. 31, 2014

Sep. 30, 2014

Dec. 31, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2014

Dec. 31, 2013

Sep. 30, 2011

Dec. 31, 2014

Sep. 30, 2014

Sep. 30, 2014

Mar. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Mar. 31, 2015

USD ($)

USD ($)

Interest Rate Swaps

Interest Rate Swaps

Interest Rate Swaps

Exchangeable Senior Notes

Exchangeable Senior Notes

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Mortgage Notes Payable

Mortgage Notes Payable

Unsecured Line of Credit

Unsecured Line of Credit

Unsecured Line of Credit

Unsecured Line of Credit

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan Due 2018 [Member]

Unsecured Term Loan Due 2018 [Member]

Unsecured Term Loan USD Portion [Member]

Unsecured Term Loan USD Portion [Member]

Unsecured Senior Notes Due Twenty Nineteen [Member]

Unsecured Senior Notes Due Twenty Twenty [Member]

Unsecured Senior Notes Due Twenty Twenty [Member]

Unsecured Senior Notes Due Twenty Twenty-Two [Member]

Unsecured Senior Notes Due Twenty Sixteen [Member]

Prime Rate [Member]

Prime Rate [Member]

Federal Funds Rate [Member]

Federal Funds Rate [Member]

Reserve-Adjusted LIBOR [Member]

Reserve-Adjusted LIBOR [Member]

Reserve-Adjusted LIBOR [Member]

Reserve-Adjusted LIBOR [Member]

Parent Company

Subsequent Event [Member]

USD ($)

Interest Rate Swaps - $200M (2)

Interest Rate Swaps - $200M (2)

USD ($)

USD ($)

USD ($)

London Interbank Offered Rate (LIBOR)

London Interbank Offered Rate (LIBOR)

Prime Rate [Member]

Federal Funds Rate

Federal Funds Rate

Projects Excluding CFLS

CFLS

USD ($)

USD ($)

USD ($)

London Interbank Offered Rate (LIBOR)

London Interbank Offered Rate (LIBOR)

USD ($)

USD ($)

Minimum [Member]

Maximum [Member]

London Interbank Offered Rate (LIBOR)

London Interbank Offered Rate (LIBOR)

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Debt [Member]

Unsecured Term Loan USD Portion [Member]

Unsecured Term Loan USD Portion [Member]

Unsecured Term Loan USD Portion [Member]

Unsecured Term Loan USD Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan USD Portion [Member]

Unsecured Term Loan USD Portion [Member]

USD ($)

Parent Company

number_of_years

USD ($)

One-Month LIBOR

One-Month LIBOR

Maximum [Member]

Minimum [Member]

Maximum [Member]

Reserve-Adjusted LIBOR [Member]

Reserve-Adjusted LIBOR [Member]

Rate

Rate

Reserve-Adjusted LIBOR [Member]

Reserve-Adjusted LIBOR [Member]

USD ($)

GBP (£)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

number_of_years

number_of_years

number_of_years

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Maximum [Member]

Debt Instruments

Debt Instrument Payable Dates

January 15 and July 15

May 1 and November 1

April 15 and October 15

January 15 and July 15

April 15 and October 15

Debt Instrument, Date of First Required Payment

15-Jul-10

1-Nov-14

15-Oct-10

15-Jan-13

15-Oct-11

Foreign Currency Exchange Rate, Translation

1.56

1.65

Investment In Real Estate Property Mortgaged

$1,400,000,000

$1,200,000,000

Increment of Dividends per Common Share Increase Exchange Rate

$0.14

Debt Instrument, Convertible, Conversion Ratio

60.2441

Debt Conversion, Original Debt, Amount

1,000

Exchange Price

$18.16

Exchangeable Note Exchange Date

1/15/15

Debt Instrument, Convertible, Conversion Price

$16.60

Dividends Payable Date of Ex-Dividend

29-Dec-14

exchangeable note redemption date

1/21/15

Long Term Debt Redemption Percentage Of Principal

100.00%

100.00%

100.00%

100.00%

100.00%

Stock Issued During Period, Shares, Conversion of Convertible Securities

4,955,377

5,764,026

Stock Issued During Period, Value, Conversion of Convertible Securities

84,300,000

Debt Instrument, Issuance Date

11-Jan-10

24-Sep-13

14-Jul-11

30-Mar-12

23-Apr-14

29-Apr-10

28-Jun-12

30-Mar-11

Line of Credit Facility, Current Borrowing Capacity

750,000,000

Initial Exchange Rate

55.0782

Debt Instrument, Face Amount

1,250,000,000

900,000,000

400,000,000

400,000,000

250,000,000

250,000,000

400,000,000

Percentage Of Long Term Debt Principal Paid By Underwriters

99.41%

98.98%

99.13%

99.37%

Debt Instrument, Interest Rate, Stated Percentage

3.75%

1.27%

[1],[2]

1.90%

[3]

1.90%

[3]

1.36%

[2]

1.57%

[3]

2.63%

6.13%

6.13%

4.25%

3.85%

Debt Instrument, Maturity Date

15-Jan-30

24-Mar-18

24-Mar-18

[1],[2]

30-Mar-17

30-Mar-17

[3]

30-Mar-17

[3]

24-Mar-18

[2]

30-Mar-17

[3]

1-May-19

15-Apr-20

15-Jul-22

15-Apr-16

Debt Instrument, Maximum Borrowing Capacity

1,800,000,000

Debt Instrument, Maturity Date Range, End

24-Sep-18

Debt Instrument, Basis Spread on Variable Rate

92.50%

170.00%

70.00%

50.00%

120.00%

92.50%

170.00%

95.00%

195.00%

20.00%

40.00%

45.00%

30.00%

15.00%

120.00%

65.00%

170.00%

115.00%

205.00%

115.00%

205.00%

Senior Notes Due Twenty Twenty Exchange Date

1/12/11

Line of Credit Facility, Unused Capacity, Commitment Fee Percentage

12.50%

30.00%

Fair Value Inputs, Cap Rate

7.25%

6.25%

Derivative, Inception Date

25-Sep-13

1-Oct-13

Derivative, Notional Amount

555,730,000

200,000,000

100,000,000

200,000,000

Derivative, Fixed Interest Rate

2.10%

0.00%

0.00%

0.00%

Derivative, Number Of Years

3

5

5

5

Principal Balance

2,712,900,000

483,896,000

698,048,000

Unsecured Senior Term Loan Maximum Borrowing Capacity

500,000,000

Unsecured Term Loans

$749,326,000

$758,786,000

$155,730,000

[3]

$165,190,000

[3]

$350,000,000

[2]

$350,000,000

[2]

$243,596,000

[3]

$243,596,000

[3]

Tender Offer Redemption Date

30-Jan-15

[1]

At DecemberB 31, 2014, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $816.0 million.

[2]

In August 2012, the Operating Partnership converted approximately $156.4 million of outstanding borrowings into British pounds sterling (bGBPb) equal to £100.0 million, which was designated as a net investment hedge to mitigate the risk of fluctuations in foreign currency exchange rates. The principal balance represents the U.S. dollar amount based on the exchange rates of $1.56 to £1.00 and $1.65 to £1.00 at DecemberB 31, 2014 and DecemberB 31, 2013, respectively. The effective interest rate includes the impact of interest rate swap agreements (see Note 9 for further discussion of interest rate swap agreements).

[3]

Mortgage notes payable assumed on April 4, 2014 in connection with the acquisition of the related properties.

Debt_Summary_of_the_Operating_

Debt (Summary of the Operating Partnership's Outstanding Consolidated Debt) (Details)

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Mar. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2011

Dec. 31, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

USD ($)

USD ($)

Unsecured Senior Notes Due Twenty Twenty [Member]

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Exchangeable Senior Notes

Exchangeable Senior Notes

Unsecured Senior Notes

Unsecured Senior Notes

Unsecured Senior Notes

Unsecured Senior Notes

Unsecured Senior Notes

Unsecured Senior Notes

Unsecured Senior Notes

Unsecured Senior Notes

Unsecured Senior Notes

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Line of Credit

Unsecured Line of Credit

Unsecured Line of Credit

Unsecured Line of Credit

Unsecured Line of Credit and Term Loan

Unsecured Line of Credit and Term Loan

Unsecured Term Loan USD Portion [Member]

Unsecured Term Loan USD Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan GBP Portion [Member]

Unsecured Term Loan Due 2018 [Member]

Unsecured Term Loan Due 2018 [Member]

USD ($)

USD ($)

9900 Belward Campus Drive

9900 Belward Campus Drive

9901 Belward Campus Drive

9901 Belward Campus Drive

Center for Life Science Boston

Center for Life Science Boston

100 College Street [Member]

100 College Street [Member]

4320 Forest Park Avenue

4320 Forest Park Avenue

300 George Street [Member]

300 George Street [Member]

Hershey Center for Applied Research

Hershey Center for Applied Research

500 Kendall Street (Kendall D)

500 Kendall Street (Kendall D)

Shady Grove Road

Shady Grove Road

University of Maryland BioPark I

University of Maryland BioPark I

University of Maryland BioPark II

University of Maryland BioPark II

University of Maryland BioPark Garage

University of Maryland BioPark Garage

University of Miami Life Science & Technology Park

University of Miami Life Science & Technology Park

USD ($)

USD ($)

USD ($)

USD ($)

Unsecured Senior Notes Due Twenty Sixteen [Member]

Unsecured Senior Notes Due Twenty Sixteen [Member]

Unsecured Senior Notes Due Twenty Nineteen [Member]

Unsecured Senior Notes Due Twenty Twenty [Member]

Unsecured Senior Notes Due Twenty Twenty [Member]

Unsecured Senior Notes Due Twenty Twenty-Two [Member]

Unsecured Senior Notes Due Twenty Twenty-Two [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

Unsecured Term Loans

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD

GBP

USD ($)

USD ($)

USD ($)

GBP (£)

Debt Instruments

Stated Interest Rate

6.13%

5.64%

5.64%

7.75%

2.40%

4.00%

[1]

6.20%

6.15%

[1]

6.38%

5.97%

5.93%

[1]

5.20%

[1]

5.20%

[1]

4.00%

[1]

3.75%

3.85%

2.63%

6.13%

4.25%

1.27%

[2],[3]

1.57%

[4]

1.90%

[4]

1.36%

[3]

Effective Interest Rate

3.99%

3.99%

7.75%

2.40%

2.70%

[1]

4.91%

4.71%

[1]

5.45%

5.97%

4.69%

[1]

4.33%

[1]

4.33%

[1]

2.89%

[1]

3.75%

3.99%

2.72%

6.27%

4.36%

1.27%

[2],[3]

2.39%

[4]

2.14%

[4]

1.67%

[3]

Principal Balance

$2,712,900,000

$483,896,000

$698,048,000

$10,486,000

$10,631,000

$12,913,000

$13,091,000

$334,447,000

$82,210,000

$0

$21,000,000

[1]

$21,000,000

[1]

$45,052,000

$0

$12,938,000

[1]

$13,449,000

[1]

$55,545,000

$57,927,000

$141,131,000

$143,067,000

$16,056,000

[1]

$16,752,000

[1]

$61,905,000

[1]

$62,946,000

[1]

$4,660,000

[1]

$4,738,000

[1]

$20,000,000

[1]

$20,000,000

[1]

Unamortized Premiums

12,861,000

11,276,000

Mortgage Notes Payable, net

496,757,000

709,324,000

Exchangeable Senior Notes

95,678,000

180,000,000

Tender Offer Redemption Date

30-Jan-15

Unsecured Senior Notes

1,300,000,000

900,000,000

400,000,000

400,000,000

400,000,000

250,000,000

250,000,000

250,000,000

250,000,000

Unamortized Discounts

-6,097,000

-4,917,000

Unsecured Senior Notes, net

1,293,903,000

895,083,000

Unsecured Term Loans

749,326,000

758,786,000

243,596,000

[4]

243,596,000

[4]

155,730,000

[4]

165,190,000

[4]

156,400,000

[4]

100,000,000

[4]

350,000,000

[3]

350,000,000

[3]

Unsecured Line of Credit

84,000,000

[2],[3]

128,000,000

[2],[3]

Total Consolidated Debt

2,719,664,000

2,671,193,000

Maturity Date

1-Jul-17

1-Jul-17

30-Jun-14

2-Aug-16

30-Jun-15

[1]

1-Jul-25

5-May-27

[1]

1-Dec-18

1-Sep-16

15-May-25

[1]

5-Sep-21

[1]

1-Sep-21

[1]

1-Feb-16

[1]

15-Jan-30

15-Apr-16

1-May-19

15-Apr-20

15-Jul-22

30-Mar-17

24-Mar-18

[2],[3]

24-Mar-18

30-Mar-17

[4]

30-Mar-17

[4]

24-Mar-18

[3]

Foreign Currency Exchange Rate, Translation

1.56

1.65

Debt Instrument, Issuance Date

11-Jan-10

30-Mar-11

23-Apr-14

29-Apr-10

28-Jun-12

30-Mar-12

14-Jul-11

24-Sep-13

Debt Instrument, Face Amount

400,000,000

400,000,000

250,000,000

250,000,000

400,000,000

900,000,000

1,250,000,000

Amortization of Financing Costs

462,500

LOC Remaining Borrowing Capacity

$816,000,000

[1]

On April 1, 2014, the Operating Partnership repaid in full the mortgage loan secured by the Company's Center for Life Science | Boston property prior to its scheduled maturity date.

[2]

At DecemberB 31, 2014, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $816.0 million.

[3]

In August 2012, the Operating Partnership converted approximately $156.4 million of outstanding borrowings into British pounds sterling (bGBPb) equal to £100.0 million, which was designated as a net investment hedge to mitigate the risk of fluctuations in foreign currency exchange rates. The principal balance represents the U.S. dollar amount based on the exchange rates of $1.56 to £1.00 and $1.65 to £1.00 at DecemberB 31, 2014 and DecemberB 31, 2013, respectively. The effective interest rate includes the impact of interest rate swap agreements (see Note 9 for further discussion of interest rate swap agreements).

[4]

Mortgage notes payable assumed on April 4, 2014 in connection with the acquisition of the related properties.

Debt_Principal_Payments_Due_fo

Debt (Principal Payments Due for Operating Partnership's Consolidated Indebtedness) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Year 1	$127,320
Year 2	650,618
Year 3	431,632
Year 4	481,804
Year 5	405,724
Thereafter	615,802	[1]
Principal Balance	2,712,900
Exchangeable Senior Notes
Exchangeable Senior Notes	$95,678		$180,000
Maturity Date	15-Jan-30
[1]	Includes $95.7 million in principal payments of the Exchangeable Senior Notes based on the Company's previously announced redemption date of JanuaryB 30, 2015, which subsequent to DecemberB 31, 2014, were exchanged in full for 5,764,026 shares of the Parent Company's common stock at the request of the holders.

Earnings_Per_Share_of_the_Pare2

Earnings Per Share of the Parent Company (Narrative) (Details) (Parent Company)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Parent Company
Antidilutive Securities Excluded from Computation of Earnings Per Share
Exchangeable Senior Notes Due 2030	8,631,164	10,405,224	10,259,496

Earnings_Per_Share_of_the_Pare3

Earnings Per Share of the Parent Company (Schedule of Earnings Per Share, Basic and Diluted) (Details) (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Earnings Per Share Basic and Diluted
Income / (loss) from discontinued operations																			($4,370)
Parent Company
Schedule of Earnings Per Share Basic and Diluted
Income from continuing operations and noncontrolling interests																	201,468	47,209	16,133
Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest																	-7,690	-565	-20
Preferred Stock Dividends and Other Adjustments																		-2,393	-14,603
Cost On Redemption Of Preferred Stock																		-6,531
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic																	1,954	1,350	1,300
Income from continuing operations available to common stockholders - basic																	191,824	36,370	210
Income (Loss) from Continuing Operations Attributable to Parent																	191,824	36,370	210
Income / (loss) from discontinued operations																			-4,370
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest																			82
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent																			-4,288
Net Income (Loss) Available to Common Stockholders, Basic	140,349	[1]	15,960	[1]	18,636	[1]	18,833	[1]	10,279	[1]	4,247	[1]	14,803	[1]	8,388	[1]	191,824	36,370	-4,078
Income Loss From Discontinued Operations Net Of Tax Attributable To Noncontrolling Interest diluted																	0	0	-82
Income Loss From Discontinued Operations Net Of Tax Diluted																	0	0	-4,370
Income (loss) from continuing operations attributable to noncontrollinginterests diluted																	5,246	819	29
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities																	5,533
Income from continuing operations attributable to common stockholders - diluted																	202,603	37,189	239
Net Income (Loss) Available to Common Stockholders, Diluted																	$202,603	$37,189	($4,131)
Weighted Average Number of Shares Outstanding, Basic																	193,003,934	182,043,391	152,752,086
Amount of Dilutive Securities Performance Units																	191,180	63,017
Amount Of Dilutive Securities Operating Partnership And Ltip Units																	5,406,682	4,290,614	2,948,301
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities																	8,631,164
Basic and Diluted																	207,232,960	186,397,022	155,700,387
Income (Loss) from Continuing Operations, Per Basic Share	$0.71																$0.99
Income (Loss) from Continuing Operations, Per Basic and Diluted Share			$0.08	[1]	$0.10	[1]	$0.10	[1]										$0.20
Income (Loss) from Continuing Operations, Per Diluted Share	$0.70																$0.98
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic and Diluted Share									$0.05	[1]	$0.02	[1]	$0.08	[1]	$0.05	[1]			($0.03)
Earnings Per Share, Basic	$0	[1]															$0.99
Earnings Per Share, Basic and Diluted	$0	[1]															$0.98
Earnings Per Share, Basic and Diluted			$0.08	[1]	$0.10	[1]	$0.10	[1]	$0.05	[1]	$0.02	[1]	$0.08	[1]	$0.05	[1]		$0.20	($0.03)
[1]	The sum of quarterly financial data may vary from the annual data due to rounding.

Earnings_Per_Unit_of_the_Opera2

Earnings Per Unit of the Operating Partnership Earnings Per Unit of the Operating Partnership (Narrative) (Details) (BIOMED REALTY, L.P.)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
BIOMED REALTY, L.P.
Antidilutive Securities Excluded from Computation of Earnings Per Share
Exchangeable Senior Notes Due 2030	8,631,164	10,405,224	10,259,496

Earnings_Per_Unit_of_the_Opera3

Earnings Per Unit of the Operating Partnership (Computations of Basic and Diluted Earnings Per Unit) (Details) (USD $)	3 Months Ended															12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Unit of the Operating Partnership
Income / (loss) from discontinued operations																		($4,370)
BIOMED REALTY, L.P.
Earnings Per Unit of the Operating Partnership
Income from continuing operations and noncontrolling interests																201,468	47,209	16,133
Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest																-2,444	254	8
Preferred Stock Dividends and Other Adjustments																	-2,393	-14,603
Cost On Redemption Of Preferred Stock																	-6,531
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic																1,954	1,354	1,326
Income from continuing operations available to common stockholders - basic																197,070	37,185	212
Income (Loss) from Continuing Operations Attributable to Parent																197,070	37,185	212
Income / (loss) from discontinued operations																		-4,370
Net Income (Loss) Available to Common Stockholders, Diluted																202,603	37,185	-4,158
Net Income Loss Attributable To Stock/Unit Holders Basic																197,070	37,185	-4,158
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities																5,533
Income from continuing operations available to common stockholders - diluted																$202,603	$37,185	$212
Weighted Average Number of Shares Outstanding, Basic																198,410,616	186,333,292	155,670,931
Amount of Dilutive Securities Performance Units																191,180	63,017
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities																8,631,164
Basic and Diluted																207,232,960	186,396,309	155,670,931
Income (Loss) from Continuing Operations, Per Basic and Diluted Share		$0	[1]	$0	[1]	$0	[1]										$0.20
Income (Loss) from Continuing Operations, Per Diluted Share	$0.70															$0.98
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic and Diluted Share								$0.05	[1]	$0.02	[1]	$0.08	[1]	$0.05	[1]			($0.03)
Earnings Per Share, Basic	$0.71															$0.99
Income (Loss) from Continuing Operations, Per Basic Share	$0.71															$0.99
Net Income per Unit Attributable to Unitholders, Basic and Diluted		$0.08	[1]	$0.10	[1]	$0.10	[1]	$0.05	[1]	$0.02	[1]	$0.08	[1]	$0.05	[1]		$0.20	($0.03)
Earnings Per Share, Diluted	$0.70															$0.98
[1]	The sum of quarterly financial data may vary from the annual data due to rounding.

Investment_in_Unconsolidated_P2

Investment in Unconsolidated Partnerships (Narrative) (Details)	Dec. 31, 2014
	PREI_LLCs
Equity Method Investments and Joint Ventures [Abstract]
Number of Investments in Limited Liability Companies	2

Investment_in_Unconsolidated_P3

Investment in Unconsolidated Partnerships (Summary of Unconsolidated Partnerships) (Details) (USD $)	3 Months Ended		12 Months Ended
	Sep. 30, 2014		Dec. 31, 2014		Dec. 31, 2013
			properties
Investment In Unconsolidated Partnerships
Equity Method Investment, Ownership Percentage			100.00%		100.00%
PREI I LLC
Investment In Unconsolidated Partnerships
Equity Method Investment, Ownership Percentage			20.00%	[1]
Company's Economic Interest			20.00%	[1]
Date Acquired	4-Apr-07	[1]
Number Of Properties In Portfolio Of Prei I Llc			2
Unsecured line of credit			$139,000,000
Line Of Credit Facility Weighted Average Interest Rate			2.21%
Line of Credit Facility, Expiration Date			13-Aug-15
PREI II LLC
Investment In Unconsolidated Partnerships
Equity Method Investment, Ownership Percentage			20.00%
Company's Economic Interest			20.00%
Date Acquired	4-Apr-07
McKellar Court
Investment In Unconsolidated Partnerships
Equity Method Investment, Ownership Percentage			22.00%	[2]
Company's Economic Interest			22.00%	[2]
Date Acquired	30-Sep-04	[2]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount			$11,800,000
Percent Of Extraordinary Cash Flow Entitled From Variable Interest Entity			75.00%
Percent Of Operating Cash Flows Entitled From Variable Interest Entity			22.00%
BioPark Fremont
Investment In Unconsolidated Partnerships
Equity Method Investment, Ownership Percentage			50.00%	[3]
Company's Economic Interest			50.00%	[3]
Date Acquired	31-May-13	[3]
[1]	PREI I LLC owns two properties in Cambridge, Massachusetts. At DecemberB 31, 2014, there were $139.0 million in outstanding borrowings on a secured loan facility held by a wholly-owned subsidiary of PREI I LLC, with a contractual interest rate of 2.21% (including the applicable credit spread) and a maturity date of AugustB 13, 2015 (with an option to extend the maturity date to August 13, 2016 at its discretion after satisfying certain conditions and paying an extension fee).
[2]	The Companybs investment in the McKellar Court partnership (maximum exposure to losses) was approximately $11.8 million at DecemberB 31, 2014. The Companybs economic interest in the McKellar Court partnership entitles it to 75% of the extraordinary cash flows after repayment of the partnersb capital contributions and 22% of the operating cash flows.
[3]	.

Investment_in_Unconsolidated_P4

Investment in Unconsolidated Partnerships (Summary of Selected Balance Sheet Information) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Equity Method Investments and Joint Ventures [Abstract]
Investments in real estate, net	$267,007	$262,753
Cash and cash equivalents (including restricted cash)	6,057	3,855
Other assets	11,599	5,301
Total assets	284,663	271,909
Mortgage notes payable and secured loan	152,056	151,968
Other liabilities	9,020	12,102
Members' equity	123,587	107,839
Total liabilities and equity	284,663	271,909
Company's net investment in unconsolidated partnerships	$35,291	$32,137

Investment_in_Unconsolidated_P5

Investment in Unconsolidated Partnerships (Summary of Selected Income Statement Information) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Equity Method Investments and Joint Ventures [Abstract]
Total revenues	$35,495		$12,930		$8,823
Total expenses	-36,013		-21,589		-19,939
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	-518		-8,659		-11,116
Company's equity in net loss of unconsolidated partnerships	745		-905		-1,389
Fees earned by the Company	$999	[1]	$260	[1]	$90	[1]
[1]	The Company acts as the operating member or partner, as applicable, and day-to-day manager for the partnerships. The Company is entitled to receive fees for providing construction and development services (as applicable) and management services to the PREI joint ventures, which are reflected in tenant recoveries and other income in the consolidated statements of operations.

Derivatives_and_Other_Financia2

Derivatives and Other Financial Instruments (Narrative) (Details)

12 Months Ended

3 Months Ended

12 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Sep. 30, 2014

Dec. 31, 2014

Dec. 31, 2014

USD ($)

USD ($)

USD ($)

InterestRateSwaps [Member]

InterestRateSwaps [Member]

InterestRateSwaps [Member]

Interest Rate Swaps

Interest Rate Swaps

Interest Rate Swaps

Forward Starting Swaps

Forward Starting Swaps

Forward Starting Swaps

Interest Rate Swaps - $200M [Member]

Interest Rate Swaps - $200M [Member]

Interest Rate Swaps - 100M GBP [Member]

Interest Rate Swaps - $200M (2)

Interest Rate Swaps - $200M (2)

GBP

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

InterestRateSwaps [Member]

Interest Rate Swaps

InterestRateSwaps [Member]

Interest Rate Swaps

Interest Rate Swaps

Interest Rate Swaps - 100M GBP [Member]

USD ($)

GBP_interest_rate_swaps

USD ($)

InterestRateSwaps [Member]

USD_interest_rate_swaps

USD_interest_rate_swaps

GBP (£)

Derivative

Derivative, Maturity Date

30-Mar-17

1-Oct-16

Derivative, Gain (Loss) on Derivative, Net

($23,000)

$416,000

($9,000)

Derivative, Inception Date

30-Mar-12

2-Aug-12

25-Sep-13

1-Oct-13

Number Of Interest Rate Swaps

4

2

Derivative, Number of Instruments Held

3

Derivative, Notional Amount

555,730,000

200,000,000

200,000,000

100,000,000

Derivative, Deferred Interest Costs

28,600,000

Derivative, Lower Remaining Maturity Range

10 years

Derivative, Deferred Interest Costs Amortization Period

4 years

Other Income

-10,259,000

-9,451,000

-8,511,000

-3,537,000

-2,619,000

-1,578,000

-6,722,000

-6,832,000

-6,933,000

Reclassification of Accumulated Other Comprehensive Loss

9,400,000

Derivative Instruments Deferred Settlement Payments

$922,000

$326,000

$118,000

Derivatives_and_Other_Financia3

Derivatives and Other Financial Instruments (Summary of Derivative Instruments) (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2014		Dec. 31, 2013
Unsecured Term Loan Due 2017 GBP Portion
Derivative
Foreign Currency Exchange Rate, Translation		1.56		1.65
Interest Rate Swaps
Derivative
Derivative, Notional Amount		$555,730
Derivative, Fair Value, Net		-1,526	[1]	900	[1]
Interest Rate Swaps | Interest Rate Swaps - $200M (1)
Derivative
Derivative, Fixed Interest Rate		1.16%
Derivative, Maturity Date		30-Mar-17
Derivative, Fair Value, Net		-1,448	[1]	-1,876	[1]
Interest Rate Swaps | Interest Rate Swaps - $200M (2)
Derivative
Derivative, Notional Amount		200,000
Derivative, Fixed Interest Rate		0.70%
Derivative, Effective Date	25-Sep-13	1-Oct-13
Derivative, Maturity Date		1-Oct-16
Derivative, Fair Value, Net		-186	[1]	-288	[1]
Interest Rate Swaps | Interest Rate Swap - 50M GBP (1)
Derivative
Derivative, Notional Amount		77,865	[2]
Derivative, Fixed Interest Rate		0.73%	[2]
Derivative, Effective Date		2-Aug-12	[2]
Derivative, Maturity Date		30-Mar-17	[2]
Derivative, Fair Value, Net		63	[1],[2]	1,545	[1],[2]
Interest Rate Swaps | Interest Rate Swap - 50M GBP (2)
Derivative
Derivative, Notional Amount		77,865	[2]
Derivative, Fixed Interest Rate		0.74%	[2]
Derivative, Effective Date		2-Aug-12	[2]
Derivative, Maturity Date		30-Mar-17	[2]
Derivative, Fair Value, Net		$45	[1],[2]	$1,519	[1],[2]
[1]	Fair-value of derivative instruments does not include any related accrued interest payable, which is included in accrued expenses on the accompanying consolidated balance sheets. Derivative valuations are classified in Level 2 of the fair-value hierarchy. Assets are included in other assets and liabilities are included in accounts payable, accrued expenses and other liabilities on the accompanying consolidated balance sheets.
[2]	Translation to U.S. dollars is based on exchange rates of $1.56 to £1.00 and $1.65 to £1.00 at DecemberB 31, 2014 and DecemberB 31, 2013, respectively.

Derivatives_and_Other_Financia4

Derivatives and Other Financial Instruments (Summary of Derivative Instruments, Effect on OCI) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative
Other Income	($10,259,000)	($9,451,000)	($8,511,000)
Derivative, Gain (Loss) on Derivative, Net	-23,000	416,000	-9,000
Interest Rate Swaps
Derivative
Other Income	-3,537,000	-2,619,000	-1,578,000
Forward Starting Swaps
Derivative
Other Income	-6,722,000	-6,832,000	-6,933,000
Effective Interest Rate Swaps [Member]
Derivative
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net			-9,000
Parent Company
Derivative
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	38,376,000
Parent Company | Interest Rate Swaps
Derivative
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax		3,497,000	-6,863,000
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Parent Company | Interest Rate Swaps
Derivative
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	$6,625,000

FairValue_of_Financial_Instrum2

Fair-Value of Financial Instruments (Fair-Value and Carrying Value of the Company's Financial Instruments) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Fair-Value of Financial Instruments
Available-for-sale securities	$58,621	[1]	$19,566	[1]
Unsecured Term Loan Due 2017 GBP Portion
Fair-Value of Financial Instruments
Foreign Currency Exchange Rate, Translation	1.56		1.65
Mortgage Notes Payable
Fair-Value of Financial Instruments
Mortgage notes payable, net	496,757		709,324
Exchangeable Senior Notes
Fair-Value of Financial Instruments
Exchangeable senior notes	95,678		180,000
Unsecured Senior Notes
Fair-Value of Financial Instruments
Unsecured senior notes, net	1,293,903		895,083
Unsecured Line of Credit
Fair-Value of Financial Instruments
Unsecured line of credit	84,000	[2],[3]	128,000	[2],[3]
Fair-Value
Fair-Value of Financial Instruments
Derivative Instruments			-1,316
Available-for-sale securities	58,621	[4]	19,566	[4]
Fair-Value | Mortgage Notes Payable
Fair-Value of Financial Instruments
Mortgage notes payable, net	502,115	[4]	730,394	[4]
Fair-Value | Exchangeable Senior Notes
Fair-Value of Financial Instruments
Exchangeable senior notes	134,619	[4]	202,626	[4]
Fair-Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Sixteen [Member]
Fair-Value of Financial Instruments
Unsecured senior notes, net	411,600	[4]	417,040	[4]
Fair-Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Nineteen [Member]
Fair-Value of Financial Instruments
Unsecured senior notes, net	398,280	[4]
Fair-Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Twenty [Member]
Fair-Value of Financial Instruments
Unsecured senior notes, net	283,250	[4]	275,600	[4]
Fair-Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Twenty-Two [Member]
Fair-Value of Financial Instruments
Unsecured senior notes, net	258,250	[4]	240,400	[4]
Fair-Value | Unsecured Term Loans | Unsecured Term Loan USD Portion [Member] | USD
Fair-Value of Financial Instruments
Unsecured senior term loans	244,945	[4]	244,751	[4]
Fair-Value | Unsecured Term Loans | Unsecured Term Loan Due 2017 GBP Portion | GBP
Fair-Value of Financial Instruments
Unsecured senior term loans	156,589	[4],[5]	165,969	[4],[5]
Fair-Value | Unsecured Term Loans | Unsecured Term Loan Due 2018 [Member]
Fair-Value of Financial Instruments
Unsecured senior term loans	350,557	[4]	350,000	[4]
Fair-Value | Unsecured Line of Credit
Fair-Value of Financial Instruments
Unsecured line of credit	83,866	[4]	128,000	[4]
Carrying Value
Fair-Value of Financial Instruments
Derivative Instruments	1,132
Available-for-sale securities	58,621		19,566
Carrying Value | Mortgage Notes Payable
Fair-Value of Financial Instruments
Mortgage notes payable, net	496,757		709,324
Carrying Value | Exchangeable Senior Notes
Fair-Value of Financial Instruments
Exchangeable senior notes	95,678		180,000
Carrying Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Sixteen [Member]
Fair-Value of Financial Instruments
Unsecured senior notes, net	399,304		398,787
Carrying Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Nineteen [Member]
Fair-Value of Financial Instruments
Unsecured senior notes, net	397,873
Carrying Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Twenty [Member]
Fair-Value of Financial Instruments
Unsecured senior notes, net	248,450		248,210
Carrying Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Twenty-Two [Member]
Fair-Value of Financial Instruments
Unsecured senior notes, net	248,275		248,086
Carrying Value | Unsecured Term Loans | Unsecured Term Loan USD Portion [Member] | USD
Fair-Value of Financial Instruments
Unsecured senior term loans	243,596		243,596
Carrying Value | Unsecured Term Loans | Unsecured Term Loan Due 2017 GBP Portion | GBP
Fair-Value of Financial Instruments
Unsecured senior term loans	155,730	[5]	165,190	[5]
Carrying Value | Unsecured Term Loans | Unsecured Term Loan Due 2018 [Member]
Fair-Value of Financial Instruments
Unsecured senior term loans	350,000		350,000
Carrying Value | Unsecured Line of Credit
Fair-Value of Financial Instruments
Unsecured line of credit	$84,000		$128,000
[1]	Determination of fair-value is classified as Level 1 in the fair-value hierarchy based on the use of quoted prices in active markets.
[2]	At DecemberB 31, 2014, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $816.0 million.
[3]	In August 2012, the Operating Partnership converted approximately $156.4 million of outstanding borrowings into British pounds sterling (bGBPb) equal to £100.0 million, which was designated as a net investment hedge to mitigate the risk of fluctuations in foreign currency exchange rates. The principal balance represents the U.S. dollar amount based on the exchange rates of $1.56 to £1.00 and $1.65 to £1.00 at DecemberB 31, 2014 and DecemberB 31, 2013, respectively. The effective interest rate includes the impact of interest rate swap agreements (see Note 9 for further discussion of interest rate swap agreements).
[4]	Fair-values of debt and derivative instruments are classified in Level 2 of the fair-value hierarchy. Fair-value of available-for-sale securities are classified in Level 1 of the fair-value hierarchy.
[5]	The principal balance represents the U.S. dollar amount based on the exchange rate of $1.56 to £1.00 and $1.65 to £1.00 at DecemberB 31, 2014 and DecemberB 31, 2013, respectively.

Acquisitions_Narrative_Details

Acquisitions (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Apr. 04, 2014
			Rate
Business Acquisition
Real Estate Investments, Net	$173,907,000
Payments to Acquire Businesses, Gross	220,961,000
Business Acquisition, Effective Date of Acquisition		5-Sep-07
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	2.60%
100 College Street [Member]
Business Acquisition
Business Acquisition, Description of Acquired Entity	100 College Street (1)
Square Footage of Real Estate Property	510,419
Combinations, Consideration Transferred and Additional Development Cost Required	191,000,000
CashAssumptionOfMortgageNCI	89,000,000
Remaining Construction Costs	102,000,000
Real Estate Investments, Net	63,361,000
Payments to Acquire Businesses, Gross	96,600,000
Business Acquisition, Effective Date of Acquisition	4-Apr-14
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners			0.00%
300 George Street [Member]
Business Acquisition
Business Acquisition, Description of Acquired Entity	300 George Street (2)
Square Footage of Real Estate Property	518,940
Real Estate Investments, Net	107,021,000
Payments to Acquire Businesses, Gross	117,000,000
Business Acquisition, Effective Date of Acquisition	4-Apr-14
BusinessAcquisitionPurchasePriceAllocationMortgageNotesPayable	46,300,000
430 Cambridge Science Center [Member]
Business Acquisition
Business Acquisition, Description of Acquired Entity	430 Cambridge Science Park (3)
Square Footage of Real Estate Property	42,410
Combinations, Consideration Transferred and Additional Development Cost Required	22,700,000
Payments to Acquire Businesses, Gross	3,836,000
Business Acquisition, Effective Date of Acquisition	15-May-14
Wake 60 [Member] [Domain]
Business Acquisition
Business Acquisition, Description of Acquired Entity	Wake 60 (4)
Square Footage of Real Estate Property	283,250
Real Estate Investments, Net	3,525,000
Payments to Acquire Businesses, Gross	3,525,000
Business Acquisition, Effective Date of Acquisition	17-Dec-14
Above Market Leases [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	63,000
Finite-Lived Intangible Asset, Useful Life	21 months
Above Market Leases [Member] | 300 George Street [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	63,000
Leases, Acquired-in-Place, Market Adjustment [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	-3,926,000
Finite-Lived Intangible Asset, Useful Life	143 months
Leases, Acquired-in-Place, Market Adjustment [Member] | 300 George Street [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	-3,926,000
Acquired Below Market Ground Leases [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	3,836,000
Finite-Lived Intangible Asset, Useful Life	1500 months
Acquired Below Market Ground Leases [Member] | 430 Cambridge Science Center [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	3,836,000
Leases, Acquired-in-Place [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	51,047,000
Finite-Lived Intangible Asset, Useful Life	159 months
Leases, Acquired-in-Place [Member] | 100 College Street [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	33,239,000
Leases, Acquired-in-Place [Member] | 300 George Street [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	17,808,000
Acquired Debt Premium [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	-3,966,000
Finite-Lived Intangible Asset, Useful Life	135 months
Acquired Debt Premium [Member] | 300 George Street [Member]
Business Acquisition
Finite-lived Intangible Assets Acquired	-3,966,000
Winstanley Enterprises LLC [Domain] | 100 College Street [Member]
Business Acquisition
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	0.00%
Winstanley Enterprises LLC [Domain] | 300 George Street [Member]
Business Acquisition
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	0.00%
Parent Company
Business Acquisition
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	13,900,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	($300,000)
Scenario, Forecast [Member] | 100 College Street [Member]
Business Acquisition
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	0.00%

Discontinued_Operations_Discon

Discontinued Operations (Discontinued Operations) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Disposal Group, Including Discontinued Operation, Revenue		$454
Disposal Group, Including Discontinued Operation, Operating Expense		272
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax		182
Date of Sale	27-Apr-12
Original Acquisition Date	5-Sep-07
Sales Price		28,000	[1]
Impairment Loss		-4,552
Income / (loss) from discontinued operations		-4,370
Forbes Boulevard
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Impairment Loss	-4,552
[1]	The sales price was equal to the fair-value of the office property received as consideration in the exchange with the independent third party.

Incentive_Award_Plan_Incentive2

Incentive Award Plan Incentive Award Plan (Narrative) (Details)	12 Months Ended
	Dec. 31, 2014
	runs
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	6,534,731
Approximate Number Of Times Simulation Was Run	100,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	0.49%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	4.64%
One Year [Member]
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Two Years [Member]
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years
Share Based Compensation Arrangement By Share Based Payment Award Vesting Percentage Unvested As Of Date Expected Term	24
Three Years [Member]
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Share Based Compensation Arrangement By Share Based Payment Award Vesting Percentage Unvested As Of Date Expected Term	36
Incentive Award Plan [Member]
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	10,740,000
BIOMED REALTY, L.P.
Incentive Award Plan Selected Data [Line Items]
Deferred Compensation Arrangement with Individual, Requisite Service Period	5 years
Minimum [Member]
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Maximum [Member]
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years

Incentive_Award_Plan_Incentive3

Incentive Award Plan Incentive Award Plan (Summary of Unvested Restricted Stock and LTIP Units) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,477,012	1,512,005	1,560,512	1,721,062
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	587,662	657,106	395,350
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	602,228	665,808	520,258
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	20,427	39,805	35,642
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$19.10	$18.91	$17	$16.09
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$18.94	$20.33	$18.46
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$18.18	$15.91	$15.17
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$19.83	$18.15	$15.97

Incentive_Award_Plan_Incentive4

Incentive Award Plan Incentive Award Plan (Incentive Award Plan Selected Data) (Details) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	years
Incentive Award Plan [Member]
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation	$11,181	$13,234	$7,300
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	11,782	13,321	9,502
Allocated Share-based Compensation Expense	12,188	10,134	9,556
Shares surrendered to the Company and retired in lieu of cash payments for taxes due on the vesting of restricted stock	225,906,000	253,671,000	178,915,000
Employee Benefits and Share-based Compensation	16,926
Share Based Compensation Arrangement Recognized Over Weighted Average Period	2.4
Performance Shares
Incentive Award Plan Selected Data [Line Items]
Share-based Compensation	4,186	4,973	3,329
Allocated Share-based Compensation Expense	3,574	2,445	1,974
Employee Benefits and Share-based Compensation	$3,179
Share Based Compensation Arrangement Recognized Over Weighted Average Period	1.8

Commitments_and_Contingencies_1

Commitments and Contingencies Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Commitment And Contingencies [Line Items]
Construction And Other Related Commitments, Current Fiscal	$511,500,000
Construction And Other Related Commitments With In One Year	393,000,000
Construction And Other Related Commitments With In Two Years	102,000,000
Construction And Other Related Commitments With In Four Years	16,500,000
Ground Lease Commitments	508,700,000
Ground lease commitments Within One Year	4,700,000
Ground Lease Commitments Within Three Years	10,000,000
Ground Lease Commitments Within Five Years	10,500,000
Ground Lease Commitments Thereafter	483,500,000
Vertex Pharmaceuticals Incorporated [Member]
Commitment And Contingencies [Line Items]
Percentage Of Revenues To Total Rental Revenues	7.20%	7.70%
Rental	34,900,000	34,500,000
Human Genome Sciences [Member]
Commitment And Contingencies [Line Items]
Percentage Of Revenues To Total Rental Revenues	9.60%	10.80%
Rental	46,500,000	48,000,000
Percent of Rental Revenue for Property Sold	4.60%
Revenue related to property sold	$22,500,000

Quarterly_Financial_Informatio4

Quarterly Financial Information of the Parent Company Quarterly Financial Information of the Parent Company (Details) (Parent Company, USD $)	3 Months Ended																12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Parent Company
Quarterly Financial Information Disclosure [Line Items]
Revenues	$165,656	[1]	$168,916	[1]	$171,161	[1]	$168,876	[1]	$157,993	[1]	$159,232	[1]	$159,639	[1]	$160,450	[1]	$674,609	$637,314	$518,167
Gain (Loss) on Sale of Properties	136,609		0		0		0										136,609	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	144,627	[1]	16,976	[1]	19,098	[1]	20,767	[1]	10,576	[1]	4,136	[1]	15,037	[1]	17,458	[1]	201,468	47,209	11,763
Net Income (Loss) Attributable to Noncontrolling Interest	-4,278	[1]	-1,016	[1]	-462	[1]	-1,934	[1]	-297	[1]	111	[1]	-234	[1]	-146	[1]	7,690	565	-62
Preferred Stock Dividends, Income Statement Impact									0	[1]	0	[1]	0	[1]	-2,393	[1]		2,393	14,603
Net Income (Loss) Available to Common Stockholders, Basic	$140,349	[1]	$15,960	[1]	$18,636	[1]	$18,833	[1]	$10,279	[1]	$4,247	[1]	$14,803	[1]	$8,388	[1]	$191,824	$36,370	($4,078)
Income (Loss) from Continuing Operations, Per Basic Share	$0.71																$0.99
Income (Loss) from Continuing Operations, Per Basic and Diluted Share			$0.08	[1]	$0.10	[1]	$0.10	[1]										$0.20
Income (Loss) from Continuing Operations, Per Diluted Share	$0.70																$0.98
Earnings Per Share, Basic	$0	[1]															$0.99
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic and Diluted Share									$0.05	[1]	$0.02	[1]	$0.08	[1]	$0.05	[1]			($0.03)
Earnings Per Share, Basic and Diluted			$0.08	[1]	$0.10	[1]	$0.10	[1]	$0.05	[1]	$0.02	[1]	$0.08	[1]	$0.05	[1]		$0.20	($0.03)
Earnings Per Share, Diluted	$0	[1]															$0.98
[1]	The sum of quarterly financial data may vary from the annual data due to rounding.

Quarterly_Financial_Informatio5

Quarterly Financial Information of the Operating Partnership Quarterly Financial Information of the Operating Partnership (Details) (BIOMED REALTY, L.P., USD $)	3 Months Ended																12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
BIOMED REALTY, L.P.
Quarterly Financial Information Disclosure [Line Items]
Revenues	$165,656	[1]	$168,916	[1]	$171,161	[1]	$168,876	[1]	$157,993	[1]	$159,232	[1]	$159,639	[1]	$160,450	[1]	$674,609	$637,314	$518,167
Gain (Loss) on Sale of Properties	136,609		0		0		0										136,609	0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	144,627	[1]	16,976	[1]	19,098	[1]	20,767	[1]	10,576	[1]	4,136	[1]	15,037	[1]	17,458	[1]	201,468	47,209	11,763
Net Income (Loss) Attributable to Noncontrolling Interest	-496	[1]	-587	[1]	52	[1]	-1,413	[1]	-12	[1]	229	[1]	29	[1]	8	[1]	2,444	-254	-8
Preferred Stock Dividends, Income Statement Impact															-2,393	[1]		2,393
Net Income (Loss) Available to Common Stockholders, Basic	$144,131	[1]	$16,389	[1]	$19,150	[1]	$19,354	[1]	$10,564	[1]	$4,365	[1]	$15,066	[1]	$8,542	[1]	$199,024	$38,539	($2,832)
Earnings Per Share, Basic	$0.71																$0.99
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic and Diluted Share									$0.05	[1]	$0.02	[1]	$0.08	[1]	$0.05	[1]			($0.03)
Earnings Per Share, Basic and Diluted			$0.08	[1]	$0.10	[1]	$0.10	[1]	$0.05	[1]	$0.02	[1]	$0.08	[1]	$0.05	[1]		$0.20	($0.03)
Earnings Per Share, Diluted	$0.70																$0.98
Income (Loss) from Continuing Operations, Per Basic Share	$0.71																$0.99
Income (Loss) from Continuing Operations, Per Basic and Diluted Share			$0	[1]	$0	[1]	$0	[1]										$0.20
Income (Loss) from Continuing Operations, Per Diluted Share	$0.70																$0.98
[1]	The sum of quarterly financial data may vary from the annual data due to rounding.

Schedule_III_Schedule_III_Deta

Schedule III Schedule III (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	$483,896
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	839,255
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	14,210
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	3,754,171
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,769,588
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	856,198
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	5,506,816
SEC Schedule III, Real Estate, Gross	6,363,014	6,003,480	4,923,166	4,402,720
SEC Schedule III, Real Estate Accumulated Depreciation	-946,439	-785,578	-603,450	-452,474
Real Estate Investment Property, Net	5,416,575	5,217,902
Albany Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,942
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	31,293
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,169
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,942
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	32,462
SEC Schedule III, Real Estate, Gross	34,404
SEC Schedule III, Real Estate Accumulated Depreciation	-7,628
Real Estate Investment Property, Net	26,776
Ardentech Court [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,742
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	5,379
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	9,406
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,742
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	14,785
SEC Schedule III, Real Estate, Gross	17,527
SEC Schedule III, Real Estate Accumulated Depreciation	-7,160
Real Estate Investment Property, Net	10,367
Ardenwood Venture [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,550
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	10,603
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	5,717
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,550
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	16,320
SEC Schedule III, Real Estate, Gross	19,870
SEC Schedule III, Real Estate Accumulated Depreciation	-5,022
Real Estate Investment Property, Net	14,848
Ardsley Park [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	6,581
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	9,088
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	33,661
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	6,581
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	42,749
SEC Schedule III, Real Estate, Gross	49,330
SEC Schedule III, Real Estate Accumulated Depreciation	-5,947
Real Estate Investment Property, Net	43,383
Balboa Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,316
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	9,493
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,217
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,316
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	10,710
SEC Schedule III, Real Estate, Gross	12,026
SEC Schedule III, Real Estate Accumulated Depreciation	-2,870
Real Estate Investment Property, Net	9,156
Bayshore Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,667
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	22,593
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	7,486
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,667
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	30,079
SEC Schedule III, Real Estate, Gross	33,746
SEC Schedule III, Real Estate Accumulated Depreciation	-11,658
Real Estate Investment Property, Net	22,088
Beckley Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,480
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	17,590
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,480
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	17,590
SEC Schedule III, Real Estate, Gross	19,070
SEC Schedule III, Real Estate Accumulated Depreciation	-4,416
Real Estate Investment Property, Net	14,654
Bernardo Center Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,580
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	13,714
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	492
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,580
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	14,206
SEC Schedule III, Real Estate, Gross	16,786
SEC Schedule III, Real Estate Accumulated Depreciation	-3,463
Real Estate Investment Property, Net	13,323
9900 Belward Campus Drive
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	10,486
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,038
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	8,274
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	953
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,038
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	9,227
SEC Schedule III, Real Estate, Gross	11,265
SEC Schedule III, Real Estate Accumulated Depreciation	-839
Real Estate Investment Property, Net	10,426
9901 Belward Campus Drive
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	12,913
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,362
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	12,185
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	14
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,362
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	12,199
SEC Schedule III, Real Estate, Gross	14,561
SEC Schedule III, Real Estate Accumulated Depreciation	-1,049
Real Estate Investment Property, Net	13,512
Nine Thousand Nine Hundred And Twenty Belward Campus Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,935
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	11,206
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,935
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	11,206
SEC Schedule III, Real Estate, Gross	15,141
SEC Schedule III, Real Estate Accumulated Depreciation	-2,539
Real Estate Investment Property, Net	12,602
320 Bent Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	88,254
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	14,136
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	102,390
SEC Schedule III, Real Estate, Gross	102,390
SEC Schedule III, Real Estate Accumulated Depreciation	-14,531
Real Estate Investment Property, Net	87,859
301 Binney Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	217,073
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	6,015
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	223,088
SEC Schedule III, Real Estate, Gross	223,088
SEC Schedule III, Real Estate Accumulated Depreciation	-40,282
Real Estate Investment Property, Net	182,806
301 Binney Garage [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	15,805
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	131
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	15,936
SEC Schedule III, Real Estate, Gross	15,936
SEC Schedule III, Real Estate Accumulated Depreciation	-1,295
Real Estate Investment Property, Net	14,641
BRDG Park Danforth Plant Science Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	31,048
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	2,896
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	33,944
SEC Schedule III, Real Estate, Gross	33,944
SEC Schedule III, Real Estate Accumulated Depreciation	-2,271
Real Estate Investment Property, Net	31,673
Bridgeview Technology Park One [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,494
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	14,716
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	19,084
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,494
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	33,800
SEC Schedule III, Real Estate, Gross	36,294
SEC Schedule III, Real Estate Accumulated Depreciation	-13,868
Real Estate Investment Property, Net	22,426
Bridgeview Technology Park Two [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,522
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	13,066
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	27
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,522
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	13,093
SEC Schedule III, Real Estate, Gross	14,615
SEC Schedule III, Real Estate Accumulated Depreciation	-3,219
Real Estate Investment Property, Net	11,396
210 Broadway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	6,917
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	16,272
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	5,934
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	6,917
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	22,206
SEC Schedule III, Real Estate, Gross	29,123
SEC Schedule III, Real Estate Accumulated Depreciation	-2,535
Real Estate Investment Property, Net	26,588
550 Broadway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,700
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	24,300
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,700
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	24,300
SEC Schedule III, Real Estate, Gross	28,000
SEC Schedule III, Real Estate Accumulated Depreciation	-3,012
Real Estate Investment Property, Net	24,988
430 Cambridge Science Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	11,911
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	11,911
SEC Schedule III, Real Estate, Gross	11,911
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	11,911
Center for Life Science Boston
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	60,000
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	407,747
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	259,943
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	60,000
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	667,690
SEC Schedule III, Real Estate, Gross	727,690
SEC Schedule III, Real Estate Accumulated Depreciation	-144,222
Real Estate Investment Property, Net	583,468
Charles Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	5,000
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	7,033
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	57
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	5,000
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	7,090
SEC Schedule III, Real Estate, Gross	12,090
SEC Schedule III, Real Estate Accumulated Depreciation	-1,639
Real Estate Investment Property, Net	10,451
320 Charles Street
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	14,020
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	32,998
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	14,020
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	32,998
SEC Schedule III, Real Estate, Gross	47,018
SEC Schedule III, Real Estate Accumulated Depreciation	-2,994
Real Estate Investment Property, Net	44,024
Chesterfield [Member] [Domain]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,350
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	6,853
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	2,598
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,350
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	9,451
SEC Schedule III, Real Estate, Gross	10,801
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	10,801
Coast 9 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	13,455
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	12,786
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	25,878
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	13,455
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	38,664
SEC Schedule III, Real Estate, Gross	52,119
SEC Schedule III, Real Estate Accumulated Depreciation	-7,472
Real Estate Investment Property, Net	44,647
100 College Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	82,210
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	13,700
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	49,661
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	62,440
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	13,700
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	112,101
SEC Schedule III, Real Estate, Gross	125,801
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	125,801
Coolidge Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,760
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	7,102
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	3,898
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,760
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	11,000
SEC Schedule III, Real Estate, Gross	13,760
SEC Schedule III, Real Estate Accumulated Depreciation	-2,348
Real Estate Investment Property, Net	11,412
Dumbarton Circle [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,723
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	3,167
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	2,819
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,723
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	5,986
SEC Schedule III, Real Estate, Gross	8,709
SEC Schedule III, Real Estate Accumulated Depreciation	-3,258
Real Estate Investment Property, Net	5,451
Eccles Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	21,257
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	608
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	9,901
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	21,257
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	10,509
SEC Schedule III, Real Estate, Gross	31,766
SEC Schedule III, Real Estate Accumulated Depreciation	-608
Real Estate Investment Property, Net	31,158
Elliott Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	10,124
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	38,911
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	63,201
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	10,124
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	102,112
SEC Schedule III, Real Estate, Gross	112,236
SEC Schedule III, Real Estate Accumulated Depreciation	-18,185
Real Estate Investment Property, Net	94,051
Twenty One Erie Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,366
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	18,372
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	148
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,366
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	18,520
SEC Schedule III, Real Estate, Gross	21,886
SEC Schedule III, Real Estate Accumulated Depreciation	-4,467
Real Estate Investment Property, Net	17,419
Forty Erie Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	7,593
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	33,765
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	4,434
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	7,593
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	38,199
SEC Schedule III, Real Estate, Gross	45,792
SEC Schedule III, Real Estate Accumulated Depreciation	-8,816
Real Estate Investment Property, Net	36,976
Four Thousand Five Hundred And Seventy Executive Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	7,685
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	9,126
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	54,018
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	7,685
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	63,144
SEC Schedule III, Real Estate, Gross	70,829
SEC Schedule III, Real Estate Accumulated Depreciation	-9,000
Real Estate Investment Property, Net	61,829
Four Thousand Seven Hundred And Seventy Five Over Four Thousand Seven Hundred And Eighty Five Executive Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	10,180
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	17,100
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	13,760
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	10,180
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	30,860
SEC Schedule III, Real Estate, Gross	41,040
SEC Schedule III, Real Estate Accumulated Depreciation	-570
Real Estate Investment Property, Net	40,470
Five Hundred Fairview Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	3,285
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	14,853
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	18,138
SEC Schedule III, Real Estate, Gross	18,138
SEC Schedule III, Real Estate Accumulated Depreciation	-3,298
Real Estate Investment Property, Net	14,840
Five Hundred And Thirty Fairview Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,703
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	694
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	46,425
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,703
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	47,119
SEC Schedule III, Real Estate, Gross	49,822
SEC Schedule III, Real Estate Accumulated Depreciation	-14,499
Real Estate Investment Property, Net	35,323
Faraday Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,370
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	7,201
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,370
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	7,201
SEC Schedule III, Real Estate, Gross	8,571
SEC Schedule III, Real Estate Accumulated Depreciation	-1,687
Real Estate Investment Property, Net	6,884
3701 Filbert Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	1,524
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	372
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	1,896
SEC Schedule III, Real Estate, Gross	1,896
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	1,896
4320 Forest Park Avenue
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	21,000
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	26,105
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	559
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	26,664
SEC Schedule III, Real Estate, Gross	26,664
SEC Schedule III, Real Estate Accumulated Depreciation	-1,969
Real Estate Investment Property, Net	24,695
Fresh Pond Research Park [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,500
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	18,322
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	23,620
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,500
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	41,942
SEC Schedule III, Real Estate, Gross	45,442
SEC Schedule III, Real Estate Accumulated Depreciation	-9,726
Real Estate Investment Property, Net	35,716
Gateway Business Park [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	116,851
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	10,981
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	12,093
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	116,851
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	23,074
SEC Schedule III, Real Estate, Gross	139,925
SEC Schedule III, Real Estate Accumulated Depreciation	-10,264
Real Estate Investment Property, Net	129,661
Gazelle Court [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	10,100
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	1,769
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	55,893
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	10,100
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	57,662
SEC Schedule III, Real Estate, Gross	67,762
SEC Schedule III, Real Estate Accumulated Depreciation	-9,408
Real Estate Investment Property, Net	58,354
George Patterson Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,575
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	11,029
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	2,128
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,575
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	13,157
SEC Schedule III, Real Estate, Gross	14,732
SEC Schedule III, Real Estate Accumulated Depreciation	-3,026
Real Estate Investment Property, Net	11,706
300 George Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	45,052
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	14,000
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	93,021
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	14,000
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	93,021
SEC Schedule III, Real Estate, Gross	107,021
SEC Schedule III, Real Estate Accumulated Depreciation	-3,790
Real Estate Investment Property, Net	103,231
Granta Park [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	32,610
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	144,050
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	322
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	32,610
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	144,372
SEC Schedule III, Real Estate, Gross	176,982
SEC Schedule III, Real Estate Accumulated Depreciation	-11,088
Real Estate Investment Property, Net	165,894
Graphics Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	800
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	6,577
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	6,972
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	800
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	13,549
SEC Schedule III, Real Estate, Gross	14,349
SEC Schedule III, Real Estate Accumulated Depreciation	-6,363
Real Estate Investment Property, Net	7,986
Fifty Hampshire [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	19,537
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	58,205
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	371
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	19,537
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	58,576
SEC Schedule III, Real Estate, Gross	78,113
SEC Schedule III, Real Estate Accumulated Depreciation	-5,552
Real Estate Investment Property, Net	72,561
Sixty Hampshire [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	4,164
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	181
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	10,986
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	4,164
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	11,167
SEC Schedule III, Real Estate, Gross	15,331
SEC Schedule III, Real Estate Accumulated Depreciation	-160
Real Estate Investment Property, Net	15,171
Heritage @ 4240 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	12,964
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	16,452
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	29,416
SEC Schedule III, Real Estate, Gross	29,416
SEC Schedule III, Real Estate Accumulated Depreciation	-989
Real Estate Investment Property, Net	28,427
Hershey Center for Applied Research
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	12,938
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	16,653
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	956
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	17,609
SEC Schedule III, Real Estate, Gross	17,609
SEC Schedule III, Real Estate Accumulated Depreciation	-1,072
Real Estate Investment Property, Net	16,537
Industrial Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	12,000
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	41,717
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	16,326
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	12,000
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	58,043
SEC Schedule III, Real Estate, Gross	70,043
SEC Schedule III, Real Estate Accumulated Depreciation	-24,172
Real Estate Investment Property, Net	45,871
Innovation Research Park at ODU I [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	26,426
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	26,426
SEC Schedule III, Real Estate, Gross	26,426
SEC Schedule III, Real Estate Accumulated Depreciation	-2,041
Real Estate Investment Property, Net	24,385
Innovation Research Park at ODU II [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	25,060
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,245
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	26,305
SEC Schedule III, Real Estate, Gross	26,305
SEC Schedule III, Real Estate Accumulated Depreciation	-1,687
Real Estate Investment Property, Net	24,618
Three Thousand Five Hundred And Twenty Five John Hopkins Court [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,993
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	18,183
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	298
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,993
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	18,481
SEC Schedule III, Real Estate, Gross	22,474
SEC Schedule III, Real Estate Accumulated Depreciation	-2,344
Real Estate Investment Property, Net	20,130
Three Thousand Five Hundred Forty Five To Three Thousand Five Hundred And Seventy Five John Hopkins Court [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,560
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	19,495
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	20,471
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,560
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	39,966
SEC Schedule III, Real Estate, Gross	43,526
SEC Schedule III, Real Estate Accumulated Depreciation	-9,476
Real Estate Investment Property, Net	34,050
Kaiser Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,430
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	6,093
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	12,751
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,430
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	18,844
SEC Schedule III, Real Estate, Gross	22,274
SEC Schedule III, Real Estate Accumulated Depreciation	-5,581
Real Estate Investment Property, Net	16,693
450 Kendall Street (Kendall G) [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	8,259
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	27,764
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	36,023
SEC Schedule III, Real Estate, Gross	36,023
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	36,023
500 Kendall Street (Kendall D)
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	55,545
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,572
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	166,308
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	690
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,572
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	166,998
SEC Schedule III, Real Estate, Gross	170,570
SEC Schedule III, Real Estate Accumulated Depreciation	-40,245
Real Estate Investment Property, Net	130,325
Kendall Crossing Apartments [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	6,665
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	782
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	7,447
SEC Schedule III, Real Estate, Gross	7,447
SEC Schedule III, Real Estate Accumulated Depreciation	-754
Real Estate Investment Property, Net	6,693
King Of Prussia Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	12,813
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	22,834
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	50,879
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	12,813
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	73,713
SEC Schedule III, Real Estate, Gross	86,526
SEC Schedule III, Real Estate Accumulated Depreciation	-23,934
Real Estate Investment Property, Net	62,592
3750 Lancaster Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	288
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	70
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	358
SEC Schedule III, Real Estate, Gross	358
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	358
Landmark At Eastview [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	14,210
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	57,526
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	417,752
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	16,943
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	458,335
SEC Schedule III, Real Estate, Gross	475,278
SEC Schedule III, Real Estate Accumulated Depreciation	-66,325
Real Estate Investment Property, Net	408,953
The Campus at Lincoln Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	37,000
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	6,278
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	37,000
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	6,278
SEC Schedule III, Real Estate, Gross	43,278
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	43,278
Thirtyseven Eleven Market Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	85,343
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,890
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	87,233
SEC Schedule III, Real Estate, Gross	87,233
SEC Schedule III, Real Estate Accumulated Depreciation	-5,579
Real Estate Investment Property, Net	81,654
Thirty Seven Thirty Seven Market Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	24,588
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	65,040
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	89,628
SEC Schedule III, Real Estate, Gross	89,628
SEC Schedule III, Real Estate Accumulated Depreciation	-1,028
Real Estate Investment Property, Net	88,600
Medical Center Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	9,620
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	43,561
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	15,010
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	9,620
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	58,571
SEC Schedule III, Real Estate, Gross	68,191
SEC Schedule III, Real Estate Accumulated Depreciation	-7,997
Real Estate Investment Property, Net	60,194
Monte Villa Parkway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,020
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	10,711
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	4,457
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,020
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	15,168
SEC Schedule III, Real Estate, Gross	16,188
SEC Schedule III, Real Estate Accumulated Depreciation	-3,044
Real Estate Investment Property, Net	13,144
Six Thousand One Hundred And Fourteen To Six Thousand One Hundred And Fifty Four Nancy Ridge Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	10,100
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	28,611
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	16,378
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	10,100
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	44,989
SEC Schedule III, Real Estate, Gross	55,089
SEC Schedule III, Real Estate Accumulated Depreciation	-8,183
Real Estate Investment Property, Net	46,906
Six thousand one hundred and twenty two NancyRidge [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,344
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	5,322
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	7,153
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,344
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	12,475
SEC Schedule III, Real Estate, Gross	14,819
SEC Schedule III, Real Estate Accumulated Depreciation	-3,169
Real Estate Investment Property, Net	11,650
Six Thousand Eight Hundred And Twenty Eight Nancy Ridge Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	4,174
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	10,592
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	4,174
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	10,592
SEC Schedule III, Real Estate, Gross	14,766
SEC Schedule III, Real Estate Accumulated Depreciation	-1,045
Real Estate Investment Property, Net	13,721
225 North 38th Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	2,360
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	606
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	2,966
SEC Schedule III, Real Estate, Gross	2,966
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	2,966
Science Center at Oyster Point
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	19,464
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	89,762
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	5,122
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	19,464
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	94,884
SEC Schedule III, Real Estate, Gross	114,348
SEC Schedule III, Real Estate Accumulated Depreciation	-12,482
Real Estate Investment Property, Net	101,866
One Research Way [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,813
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	983
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	12,931
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,813
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	13,914
SEC Schedule III, Real Estate, Gross	15,727
SEC Schedule III, Real Estate Accumulated Depreciation	-2,078
Real Estate Investment Property, Net	13,649
Pacific Center Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	5,400
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	11,493
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	3,399
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	5,400
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	14,892
SEC Schedule III, Real Estate, Gross	20,292
SEC Schedule III, Real Estate Accumulated Depreciation	-4,262
Real Estate Investment Property, Net	16,030
Pacific Research Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	74,147
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	246,167
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	61,099
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	74,147
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	307,266
SEC Schedule III, Real Estate, Gross	381,413
SEC Schedule III, Real Estate Accumulated Depreciation	-70,843
Real Estate Investment Property, Net	310,570
Three Thousand Five Hundred Paramount Parkway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,080
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	14,535
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	26
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,080
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	14,561
SEC Schedule III, Real Estate, Gross	15,641
SEC Schedule III, Real Estate Accumulated Depreciation	-2,362
Real Estate Investment Property, Net	13,279
Patriot [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	848
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	6,906
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	595
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	848
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	7,501
SEC Schedule III, Real Estate, Gross	8,349
SEC Schedule III, Real Estate Accumulated Depreciation	-1,372
Real Estate Investment Property, Net	6,977
Phoenixville Pike [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,204
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	10,880
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	13,472
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,204
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	24,352
SEC Schedule III, Real Estate, Gross	25,556
SEC Schedule III, Real Estate Accumulated Depreciation	-8,916
Real Estate Investment Property, Net	16,640
Wake 60 [Member] [Domain]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,363
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,144
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,363
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	1,144
SEC Schedule III, Real Estate, Gross	2,507
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	2,507
Piedmont Triad Research Wake 90 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,160
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	41,198
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	23,329
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,160
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	64,527
SEC Schedule III, Real Estate, Gross	66,687
SEC Schedule III, Real Estate Accumulated Depreciation	-2,409
Real Estate Investment Property, Net	64,278
1701 / 1711 Research Blvd [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	7,492
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	8,834
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	19,104
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	7,492
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	27,938
SEC Schedule III, Real Estate, Gross	35,430
SEC Schedule III, Real Estate Accumulated Depreciation	-1,938
Real Estate Investment Property, Net	33,492
Road Tothe Cure [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	4,430
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	19,128
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	15,079
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	4,430
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	34,207
SEC Schedule III, Real Estate, Gross	38,637
SEC Schedule III, Real Estate Accumulated Depreciation	-7,177
Real Estate Investment Property, Net	31,460
San Diego Science Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,871
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	21,875
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	3,508
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,871
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	25,383
SEC Schedule III, Real Estate, Gross	29,254
SEC Schedule III, Real Estate Accumulated Depreciation	-6,852
Real Estate Investment Property, Net	22,402
Ten Thousand Two Hundred And Forty Science Center Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	4,079
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	12,124
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	22
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	4,079
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	12,146
SEC Schedule III, Real Estate, Gross	16,225
SEC Schedule III, Real Estate Accumulated Depreciation	-1,887
Real Estate Investment Property, Net	14,338
Science Center Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,630
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	16,029
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,737
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,630
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	17,766
SEC Schedule III, Real Estate, Gross	20,396
SEC Schedule III, Real Estate Accumulated Depreciation	-4,161
Real Estate Investment Property, Net	16,235
Shady Grove Road
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	141,131
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	28,895
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	197,548
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	3,371
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	28,895
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	200,919
SEC Schedule III, Real Estate, Gross	229,814
SEC Schedule III, Real Estate Accumulated Depreciation	-44,840
Real Estate Investment Property, Net	184,974
Sidney Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	7,579
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	50,459
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	202
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	7,579
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	50,661
SEC Schedule III, Real Estate, Gross	58,240
SEC Schedule III, Real Estate Accumulated Depreciation	-12,148
Real Estate Investment Property, Net	46,092
Sorrento Plaza [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,364
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	5,946
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	874
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,364
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	6,820
SEC Schedule III, Real Estate, Gross	9,184
SEC Schedule III, Real Estate Accumulated Depreciation	-1,178
Real Estate Investment Property, Net	8,006
One One Three Eight Eight Sorrento Valley Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,366
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	8,514
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	604
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,366
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	9,118
SEC Schedule III, Real Estate, Gross	11,484
SEC Schedule III, Real Estate Accumulated Depreciation	-1,439
Real Estate Investment Property, Net	10,045
Sorrento Valley Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	4,140
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	2,700
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	17,228
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	4,140
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	19,928
SEC Schedule III, Real Estate, Gross	24,068
SEC Schedule III, Real Estate Accumulated Depreciation	-2,700
Real Estate Investment Property, Net	21,368
ThreeEleven South Sarah [Member] [Domain]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	5,180
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	460
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	5,180
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	460
SEC Schedule III, Real Estate, Gross	5,640
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	5,640
Spring Mill Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,074
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	7,948
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,262
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,074
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	9,210
SEC Schedule III, Real Estate, Gross	10,284
SEC Schedule III, Real Estate Accumulated Depreciation	-2,410
Real Estate Investment Property, Net	7,874
Summers Ridge [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	47,301
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	47,301
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	0
SEC Schedule III, Real Estate, Gross	47,301
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	47,301
Trade Centre Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	3,275
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	15,404
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	3,275
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	15,404
SEC Schedule III, Real Estate, Gross	18,679
SEC Schedule III, Real Estate Accumulated Depreciation	-3,980
Real Estate Investment Property, Net	14,699
Torreyana Road [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	7,660
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	24,468
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	4,258
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	7,660
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	28,726
SEC Schedule III, Real Estate, Gross	36,386
SEC Schedule III, Real Estate Accumulated Depreciation	-5,906
Real Estate Investment Property, Net	30,480
Nine Thousand Eight Hundred And Sixty Five Towne Centre Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	5,738
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	2,991
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	20,206
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	5,738
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	23,197
SEC Schedule III, Real Estate, Gross	28,935
SEC Schedule III, Real Estate Accumulated Depreciation	-6,188
Real Estate Investment Property, Net	22,747
Nine Thousand Eight Hundred And Eighty Five Towne Centre Drive [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	4,982
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	28,513
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	4,982
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	28,513
SEC Schedule III, Real Estate, Gross	33,495
SEC Schedule III, Real Estate Accumulated Depreciation	-7,396
Real Estate Investment Property, Net	26,099
Tributary Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,060
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	10,597
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,060
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	10,597
SEC Schedule III, Real Estate, Gross	12,657
SEC Schedule III, Real Estate Accumulated Depreciation	-2,660
Real Estate Investment Property, Net	9,997
Nine Hundred Uniqema Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	404
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	3,692
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	69
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	404
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	3,761
SEC Schedule III, Real Estate, Gross	4,165
SEC Schedule III, Real Estate Accumulated Depreciation	-1,227
Real Estate Investment Property, Net	2,938
One Thousand Uniqema Boulevard [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,350
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	13,229
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	201
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,350
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	13,430
SEC Schedule III, Real Estate, Gross	14,780
SEC Schedule III, Real Estate Accumulated Depreciation	-4,310
Real Estate Investment Property, Net	10,470
Baltimore Garage, LLC [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	4,660
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	16,234
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	16,234
SEC Schedule III, Real Estate, Gross	16,234
SEC Schedule III, Real Estate Accumulated Depreciation	-941
Real Estate Investment Property, Net	15,293
University of Maryland BioPark I
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	77,961
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	19,784
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	83
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	19,867
SEC Schedule III, Real Estate, Gross	19,867
SEC Schedule III, Real Estate Accumulated Depreciation	-1,322
Real Estate Investment Property, Net	18,545
University of Maryland BioPark II
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	98,559
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	4,657
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	103,216
SEC Schedule III, Real Estate, Gross	103,216
SEC Schedule III, Real Estate Accumulated Depreciation	-6,516
Real Estate Investment Property, Net	96,700
University of Maryland BioPark III [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	6,061
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	8,915
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	6,061
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	8,915
SEC Schedule III, Real Estate, Gross	14,976
SEC Schedule III, Real Estate Accumulated Depreciation	0
Real Estate Investment Property, Net	14,976
University of Maryland BioPark Garage
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	20,000
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	754
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	76,760
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	4,186
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	754
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	80,946
SEC Schedule III, Real Estate, Gross	81,700
SEC Schedule III, Real Estate Accumulated Depreciation	-5,038
Real Estate Investment Property, Net	76,662
University Tech Park at IIT [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	44,525
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	4,620
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	49,145
SEC Schedule III, Real Estate, Gross	49,145
SEC Schedule III, Real Estate Accumulated Depreciation	-2,260
Real Estate Investment Property, Net	46,885
Vassar Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,040
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	13,841
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	13,123
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,040
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	26,964
SEC Schedule III, Real Estate, Gross	29,004
SEC Schedule III, Real Estate Accumulated Depreciation	-8,543
Real Estate Investment Property, Net	20,461
Waples Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,470
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	5,473
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	9,183
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,470
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	14,656
SEC Schedule III, Real Estate, Gross	17,126
SEC Schedule III, Real Estate Accumulated Depreciation	-8,158
Real Estate Investment Property, Net	8,968
Wateridge Circle [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	6,536
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	34,462
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	7,157
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	6,536
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	41,619
SEC Schedule III, Real Estate, Gross	48,155
SEC Schedule III, Real Estate Accumulated Depreciation	-5,003
Real Estate Investment Property, Net	43,152
Wake Forest Biotech Place [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,266
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	87,812
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	48
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,266
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	87,860
SEC Schedule III, Real Estate, Gross	89,126
SEC Schedule III, Real Estate Accumulated Depreciation	-4,160
Real Estate Investment Property, Net	84,966
Walnut Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	5,200
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	36,067
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	5,200
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	36,067
SEC Schedule III, Real Estate, Gross	41,267
SEC Schedule III, Real Estate Accumulated Depreciation	-9,098
Real Estate Investment Property, Net	32,169
Weston Parkway [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	536
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	5,022
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	130
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	536
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	5,152
SEC Schedule III, Real Estate, Gross	5,688
SEC Schedule III, Real Estate Accumulated Depreciation	-716
Real Estate Investment Property, Net	4,972
Six Hundred And Seventy Five Only West Kendall Street Kendalla [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	4,922
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	121,182
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	2,470
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	4,922
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	123,652
SEC Schedule III, Real Estate, Gross	128,574
SEC Schedule III, Real Estate Accumulated Depreciation	-29,620
Real Estate Investment Property, Net	98,954
Fifty West Watkins Mill [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,451
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	11,611
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	263
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,451
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	11,874
SEC Schedule III, Real Estate, Gross	13,325
SEC Schedule III, Real Estate Accumulated Depreciation	1,887
Real Estate Investment Property, Net	11,438
West Watkins Mill [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	2,320
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	10,393
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	206
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	2,320
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	10,599
SEC Schedule III, Real Estate, Gross	12,919
SEC Schedule III, Real Estate Accumulated Depreciation	-2,017
Real Estate Investment Property, Net	10,902
Woodside Technology Park
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	13,350
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	57,310
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	9,261
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	13,350
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	66,571
SEC Schedule III, Real Estate, Gross	79,921
SEC Schedule III, Real Estate Accumulated Depreciation	-6,203
Real Estate Investment Property, Net	73,718
Two Hundred And Seventeenth Place [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	7,125
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	3,529
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	14,798
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	7,125
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	18,327
SEC Schedule III, Real Estate, Gross	25,452
SEC Schedule III, Real Estate Accumulated Depreciation	-5,158
Real Estate Investment Property, Net	$20,294

Schedule_III_Schedule_III_Cons

Schedule III Schedule III Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	$483,896
SEC Schedule III, Real Estate, Gross	6,363,014	6,003,480	4,923,166	4,402,720
SEC Schedule III, Real Estate Accumulated Depreciation, Real Estate Sold	43,328	1,374	1,530
SEC Schedule III, Real Estate Accumulated Depreciation, Depreciation Expense	-204,189	-183,502	-152,506
SEC Schedule III, Real Estate, Other Acquisitions	173,907	835,999	395,560
SEC Schedule III, Real Estate, Cost of Real Estate Sold	-200,974	-4,155	-33,048
SEC Schedule III, Real Estate, Other Additions	386,601	248,470	157,934
Real Estate Investment Property, at Cost	6,363,014	6,003,480
Real Estate Investment Property, Accumulated Depreciation	946,439	785,578
SEC Schedule III, Real Estate Accumulated Depreciation	-946,439	-785,578	-603,450	-452,474
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	839,255
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	14,210
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	3,754,171
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,769,588
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	856,198
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	5,506,816
3750 Lancaster Avenue [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate, Gross	358
SEC Schedule III, Real Estate Accumulated Depreciation	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	288
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	70
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	358
225 North 38th Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate, Gross	2,966
SEC Schedule III, Real Estate Accumulated Depreciation	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	2,360
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	606
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	2,966
Wake 60 [Member] [Domain]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate, Gross	2,507
SEC Schedule III, Real Estate Accumulated Depreciation	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	1,363
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,144
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	1,363
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	1,144
300 George Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	45,052
SEC Schedule III, Real Estate, Gross	107,021
SEC Schedule III, Real Estate Accumulated Depreciation	-3,790
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	14,000
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	93,021
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	14,000
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	93,021
100 College Street [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	82,210
SEC Schedule III, Real Estate, Gross	125,801
SEC Schedule III, Real Estate Accumulated Depreciation	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	13,700
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	49,661
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	62,440
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	13,700
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	112,101
430 Cambridge Science Center [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation, Amount of Encumbrances	0
SEC Schedule III, Real Estate, Gross	11,911
SEC Schedule III, Real Estate Accumulated Depreciation	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Land	0
Real Estate And Accumulated Depreciation Initial Cost Of Ground Lease	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	11,911
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Land	0
SEC Schedule III, Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	$11,911