Biomed Realty Trust 10-Q 30 Oct 14 2014 Q3 Quarterly report Financial data

Document_Entity_Information

Document Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 30, 2014
Entity Information [Line Items]	'	'
Entity Registrant Name	'BioMed Realty Trust Inc	'
Entity Central Index Key	'0001289236	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	197,442,432
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'
BIOMED REALTY, L.P.	'	'
Entity Information [Line Items]	'	'
Entity Registrant Name	'BioMed Realty L P	'
Entity Central Index Key	'0001301932	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Non-accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments in real estate, net	$5,535,115	$5,217,902
Investments in unconsolidated partnerships	36,275	32,137
Parent Company	'	'
Investments in real estate, net	5,535,115	5,217,902
Investments in unconsolidated partnerships	36,275	32,137
Cash and cash equivalents	33,864	34,706
Accounts receivable, net	18,843	8,421
Accrued straight-line rents, net	183,904	173,779
Deferred leasing costs, net	224,824	198,067
Other assets	205,487	307,589
Total assets	6,238,312	5,972,601
Liabilities [Abstract]	'	'
Mortgage notes payable, net	478,543	709,324
Exchangeable senior notes	95,678	180,000
Unsecured senior notes, net	1,293,572	895,083
Unsecured senior term loans	755,876	758,786
Unsecured line of credit	229,000	128,000
Accounts payable, accrued expenses and other liabilities	375,933	314,383
Total liabilities	3,228,602	2,985,576
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]	'	'
Common stock, $.01 par value, 250,000,000 shares authorized, 197,455,157 shares and 192,115,002 shares issued and outstanding at September 30, 2014 and December 31, 2013, respectively	1,975	1,921
Additional paid-in capital	3,643,957	3,554,558
Accumulated other comprehensive loss, net	-20,915	-32,923
Dividends in excess of earnings	-675,763	-583,569
Total stockholders' equity	2,949,254	2,939,987
Noncontrolling interests / Noncontrolling interests deficit	60,456	47,038
Total equity / capital	3,009,710	2,987,025
Total liabilities and equity / capital	6,238,312	5,972,601
BIOMED REALTY, L.P.	'	'
Investments in real estate, net	5,535,115	5,217,902
Investments in unconsolidated partnerships	36,275	32,137
Cash and cash equivalents	33,864	34,706
Accounts receivable, net	18,843	8,421
Accrued straight-line rents, net	183,904	173,779
Deferred leasing costs, net	224,824	198,067
Other assets	205,487	307,589
Total assets	6,238,312	5,972,601
Liabilities [Abstract]	'	'
Mortgage notes payable, net	478,543	709,324
Exchangeable senior notes	95,678	180,000
Unsecured senior notes, net	1,293,572	895,083
Unsecured senior term loans	755,876	758,786
Unsecured line of credit	229,000	128,000
Accounts payable, accrued expenses and other liabilities	375,933	314,383
Total liabilities	3,228,602	2,985,576
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]	'	'
Limited partners' capital, 5,405,474 and 5,415,974 units issued and outstanding at September 30, 2014 and December 31, 2013, respectively	44,836	45,708
General partner's capital, 197,455,157 and 192,115,002 units issued and outstanding at September 30, 2014 and December 31, 2013, respectively	2,967,581	2,970,650
Accumulated other comprehensive loss, net	-18,327	-30,663
Total partners' capital	2,994,090	2,985,695
Noncontrolling interests / Noncontrolling interests deficit	15,620	1,330
Total equity / capital	3,009,710	2,987,025
Total liabilities and equity / capital	$6,238,312	$5,972,601

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parentheticals) (USD $)	Sep. 30, 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	197,455,157	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	197,455,157	192,115,002
General Partners' Capital Account, Units Outstanding	197,455,157	192,115,002
Common Stock | Parent Company	'	'
Common Stock, Shares Outstanding	197,455,157	192,115,002

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Expenses:	'	'	'	'
Equity in net loss of unconsolidated partnerships	$733	($112)	$585	($697)
Parent Company	'	'	'	'
Revenues:	'	'	'	'
Rental	122,838	116,884	363,788	327,932
Tenant recoveries	42,626	38,907	121,641	104,037
Other revenue	3,452	3,441	23,524	47,352
Total revenues	168,916	159,232	508,953	479,321
Expenses:	'	'	'	'
Rental operations	54,899	51,688	161,058	134,182
Depreciation and amortization	64,452	61,898	189,597	186,219
General and administrative	12,768	11,934	37,153	32,358
Acquisition-related expenses	487	907	2,871	5,263
Total expenses	132,606	126,427	390,679	358,022
Income from operations	36,310	32,805	118,274	121,299
Equity in net loss of unconsolidated partnerships	733	-112	585	-697
Interest expense, net	-22,215	-27,870	-73,356	-79,890
Other expense	2,148	-687	11,338	-4,079
Net income / (loss)	16,976	4,136	56,841	36,633
Net (income) / loss attributable to noncontrolling interests	-1,016	111	-3,412	-268
Net income / (loss) attributable to the Company/Operating Partnership	15,960	4,247	53,429	36,365
Preferred stock dividends / unit distributions	0	0	'	-2,393
Cost on redemption of preferred stock / units	0	0	'	-6,531
Net income / (loss) available to common stockholders/unitholders	15,960	4,247	53,429	27,441
Net income / (loss) per share / unit available to common stockholders / unitholders	$0.08	$0.02	$0.27	$0.15
Weighted Average Number of Shares Outstanding, Basic	194,022,619	190,646,722	191,988,661	179,138,169
Weighted Average Number of Shares Outstanding, Diluted	199,574,893	196,131,643	197,651,357	183,121,240
BIOMED REALTY, L.P.	'	'	'	'
Revenues:	'	'	'	'
Rental	122,838	116,884	363,788	327,932
Tenant recoveries	42,626	38,907	121,641	104,037
Other revenue	3,452	3,441	23,524	47,352
Total revenues	168,916	159,232	508,953	479,321
Expenses:	'	'	'	'
Rental operations	54,899	51,688	161,058	134,182
Depreciation and amortization	64,452	61,898	189,597	186,219
General and administrative	12,768	11,934	37,153	32,358
Acquisition-related expenses	487	907	2,871	5,263
Total expenses	132,606	126,427	390,679	358,022
Income from operations	36,310	32,805	118,274	121,299
Equity in net loss of unconsolidated partnerships	733	-112	585	-697
Interest expense, net	-22,215	-27,870	-73,356	-79,890
Other expense	2,148	-687	11,338	-4,079
Net income / (loss)	16,976	4,136	56,841	36,633
Net (income) / loss attributable to noncontrolling interests	-587	229	-1,948	266
Net income / (loss) attributable to the Company/Operating Partnership	16,389	4,365	54,893	36,899
Preferred stock dividends / unit distributions	'	'	'	-2,393
Cost on redemption of preferred stock / units	'	'	'	-6,531
Net income / (loss) available to common stockholders/unitholders	$16,389	$4,365	$54,893	$27,975
Net income / (loss) per share / unit available to common stockholders / unitholders	$0.08	$0.02	$0.27	$0.15
Weighted Average Number of Shares Outstanding, Basic	199,428,093	196,062,696	197,395,750	183,048,587
Weighted Average Number of Shares Outstanding, Diluted	199,574,893	196,131,643	197,651,357	183,120,286

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Parent Company	'	'	'	'
Net income / (loss)	$16,976	$4,136	$56,841	$36,633
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	-1,472	1,866	-484	-252
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	169	-771	-749	4,405
Amortization of Other Deferred Charges	1,677	1,705	5,052	5,134
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	'	'	-9,322	'
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	3,550	2,280	20,300	8,435
Other Comprehensive Income (Loss), Net of Tax	3,924	5,080	14,797	17,722
Comprehensive Income / loss, Net of Tax, Including Portion Attributable to Noncontrolling Interest	20,900	9,216	71,638	54,355
Comprehensive (income) / loss, Net of Tax, Attributable to Noncontrolling Interest	-1,767	-493	-6,201	-1,883
Comprehensive income / (loss), Net of Tax, Attributable to Parent	19,133	8,723	65,437	52,472
BIOMED REALTY, L.P.	'	'	'	'
Net income / (loss)	16,976	4,136	56,841	36,633
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	-1,472	1,866	-484	-252
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	169	-771	-749	4,405
Amortization of Other Deferred Charges	1,677	1,705	5,052	5,134
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	'	'	-9,322	'
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	3,550	2,280	20,300	8,435
Other Comprehensive Income (Loss), Net of Tax	3,924	5,080	14,797	17,722
Comprehensive Income / loss, Net of Tax, Including Portion Attributable to Noncontrolling Interest	20,900	9,216	71,638	54,355
Comprehensive (income) / loss, Net of Tax, Attributable to Noncontrolling Interest	-1,253	229	-4,409	266
Comprehensive income / (loss), Net of Tax, Attributable to Parent	19,647	9,445	67,229	54,621
Interest Rate Swaps | BIOMED REALTY, L.P.	'	'	'	'
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	'	'	($749)	'

Consolidated_Statement_of_Equi

Consolidated Statement of Equity (USD $)

Parent Company

BIOMED REALTY, L.P.

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

Interest Rate Swaps

In Thousands, except Share data

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

BIOMED REALTY, L.P.

BIOMED REALTY, L.P.

BIOMED REALTY, L.P.

BIOMED REALTY, L.P.

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

'

'

374,278

'

'

'

'

'

'

'

'

'

374,278

'

'

Net issuances of unvested restricted common stock/OP units - value

-4,425

-4,425

4

-4,429

'

'

'

-4,425

-4,425

'

'

'

-4,425

'

'

Stock Issued During Period, Shares, Conversion of Convertible Securities

'

'

4,955,377

'

'

'

'

'

'

'

'

0

4,955,377

'

'

Stock Issued During Period, Value, Conversion of Convertible Securities, Net of Adjustments

84,179

84,179

50

84,129

'

'

'

84,179

84,179

'

'

'

84,179

'

'

Conversion of OP units to common stock - shares

'

'

10,500

'

'

'

'

'

'

'

'

-10,500

10,500

'

'

Conversion of OP units to common stock - value

'

0

'

-51

'

'

'

-51

0

51

'

51

-51

'

'

Vesting of share-based awards

11,137

11,137

'

11,137

'

'

'

11,137

11,137

'

'

'

11,137

'

'

Reallocation of equity to noncontrolling interests/limited partners

'

0

'

-1,338

'

'

'

-1,338

'

1,338

'

1,666

-1,666

'

'

Common stock dividends

-145,623

'

'

'

'

'

-145,623

-145,623

'

'

'

'

'

'

'

OP unit distributions

-4,053

-149,676

'

'

'

'

'

'

-149,676

-4,053

'

-4,053

-145,623

'

'

Noncontrolling Interest, Increase from Business Combination

9,881

9,881

'

'

'

'

'

'

0

9,881

9,881

'

'

'

'

Net income / (loss)

56,841

56,841

'

'

'

'

53,429

53,429

54,893

3,412

1,948

1,464

53,429

'

'

Other Comprehensive Income (Loss), Foreign currency translation adjustment

-484

-484

'

'

-471

-484

'

-471

-484

-13

'

'

'

'

'

Marketable Securities, Realized Gain (Loss)

-9,322

-9,322

'

'

-7,784

-7,784

'

-7,784

-7,784

-1,538

-1,538

'

'

'

'

Unrealized loss on equity securities

20,300

20,300

'

'

16,073

16,301

'

16,073

16,301

4,227

3,999

'

'

'

'

Amortization of deferred interest costs

5,052

'

'

'

4,918

5,052

'

4,918

5,052

134

'

'

'

5,052

'

Unrealized gain on derivative instruments, net

-749

-749

'

'

-728

-749

'

-728

-749

-21

'

'

'

'

-749

Balance - value - period end at Sep. 30, 2014

3,009,710

3,009,710

1,975

3,643,957

-20,915

-18,327

-675,763

2,949,254

2,994,090

60,456

15,620

44,836

2,967,581

'

'

Balance - units - period end at Sep. 30, 2014

'

'

'

'

'

'

'

'

'

'

'

5,405,474

197,455,157

'

'

Balance - shares - period end at Sep. 30, 2014

'

'

197,455,157

'

'

'

'

'

'

'

'

'

'

'

'

Balance - value - period start at Jun. 30, 2014

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Issued During Period, Shares, Conversion of Convertible Securities

'

'

4,955,377

'

'

'

'

'

'

'

'

'

'

'

'

Net income / (loss)

16,976

16,976

'

'

'

'

'

'

'

'

'

'

'

'

'

Other Comprehensive Income (Loss), Foreign currency translation adjustment

-1,472

-1,472

'

'

'

'

'

'

'

'

'

'

'

'

'

Unrealized gain on derivative instruments, net

169

169

'

'

'

'

'

'

'

'

'

'

'

'

'

Balance - value - period end at Sep. 30, 2014

$3,009,710

$3,009,710

$1,975

'

'

'

'

'

'

'

'

'

'

'

'

Balance - shares - period end at Sep. 30, 2014

'

'

197,455,157

'

'

'

'

'

'

'

'

'

'

'

'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
BIOMED REALTY, L.P.	'	'
Interest Paid, Capitalized	$15,734	$9,999
Operating Activities	'	'
Net income / (loss)	56,841	36,633
Adjustments to reconcile net income to net cash provided by operating activities	'	'
Depreciation and amortization	189,597	186,219
Allowance for doubtful accounts	526	730
Non-cash revenue adjustments	942	9,590
Other non-cash adjustments	5,146	9,903
Compensation expense related to restricted common stock and LTIP units / share-based payments	11,137	9,567
Distributions representing a return on capital from unconsolidated partnerships	399	178
Change in operating assets and liabilities	'	'
Accounts receivable	-10,607	-5,573
Accrued straight-line rents	-10,466	-17,470
Deferred leasing costs	-10,526	-12,833
Other assets	-24,478	-14,001
Accounts payable, accrued expenses and other liabilities	15,355	1,759
Net cash provided by operating activities	223,866	204,702
Investing activities	'	'
Purchases of investments in real estate and related intangible assets	-130,458	-471,910
Capital expenditures	-300,716	-142,833
Contributions from historic tax credit transactions, net of deferred costs	22,557	8,620
Contributions From New Market Tax Credit Transaction Net Of Deferred Costs	'	4,078
Draws on construction loan receivable	-39,769	-95,303
Proceeds from Collection of Loans Receivable	184,239	'
Contributions to unconsolidated partnerships, net	-4,760	-983
Purchases of debt and equity securities	-15,725	-12,674
Proceeds from the sale of debt and equity securities	13,952	6,103
Net cash used in investing activities	-270,680	-704,902
Financing activities	'	'
Proceeds from issuance of OP units	'	641,130
Redemption of Series A preferred stock	'	-198,000
Payments of Debt Issuance Costs	3,101	7,172
Unsecured line of credit proceeds	732,000	687,000
Unsecured line of credit payments	-631,000	-785,000
Proceeds from Sale and Collection of Mortgage Notes Receivable	39,237	4,182
Principal payments on mortgage notes payable	-340,124	-112,837
Proceeds from Issuance of Other Long-term Debt	0	350,000
Proceeds from Issuance of Senior Long-term Debt	397,632	0
Proceeds from (Repayments of) Restricted Cash, Financing Activities	'	60,000
Dividends paid to common stockholders / unitholders	-148,464	-123,751
Dividends paid to preferred stockholders / unitholders	'	-6,045
Net cash provided by financing activities	46,180	509,507
Effect of exchange rate changes on cash and cash equivalents	-208	-53
Net increase / (decrease) in cash and cash equivalents	-842	9,254
Cash and cash equivalents at beginning of period	34,706	19,976
Cash and cash equivalents at end of period	33,864	29,230
Supplemental disclosure of cash flow information:	'	'
Cash paid during the period for interest (net of amounts capitalized of $15,734 and $9,999 during the nine months ended September 30, 2014 and 2013, respectively)	59,233	67,079
Supplemental disclosure of non-cash investing and financing activities:	'	'
Accrual for common stock dividends / unit distributions declared	50,714	46,418
Accrued additions to real estate and related intangible assets	113,704	60,246
Debt Instrument, Unamortized Premium	3,966	8,671
Equity issued in connection with Wexford Merger and 320 Charles Street acquisition	0	165,114
Notes Assumed	71,937	254,660
Stock Issued During Period, Value, Conversion of Convertible Securities	84,322	0
Equity issued in connection with 100 College Street and 300 George Street acquisition	21,740	'
Parent Company	'	'
Interest Paid, Capitalized	15,734	9,999
Operating Activities	'	'
Net income / (loss)	56,841	36,633
Adjustments to reconcile net income to net cash provided by operating activities	'	'
Depreciation and amortization	189,597	186,219
Allowance for doubtful accounts	526	730
Non-cash revenue adjustments	942	9,590
Other non-cash adjustments	5,146	9,903
Compensation expense related to restricted common stock and LTIP units / share-based payments	11,137	9,567
Distributions representing a return on capital from unconsolidated partnerships	399	178
Change in operating assets and liabilities	'	'
Accounts receivable	-10,607	-5,573
Accrued straight-line rents	-10,466	-17,470
Deferred leasing costs	-10,526	-12,833
Other assets	-24,478	-14,001
Accounts payable, accrued expenses and other liabilities	15,355	1,759
Net cash provided by operating activities	223,866	204,702
Investing activities	'	'
Purchases of investments in real estate and related intangible assets	-130,458	-471,910
Capital expenditures	-300,716	-142,833
Contributions from historic tax credit transactions, net of deferred costs	22,557	8,620
Contributions From New Market Tax Credit Transaction Net Of Deferred Costs	'	4,078
Draws on construction loan receivable	-39,769	-95,303
Proceeds from Collection of Loans Receivable	184,239	'
Contributions to unconsolidated partnerships, net	-4,760	-983
Purchases of debt and equity securities	-15,725	-12,674
Proceeds from the sale of debt and equity securities	13,952	6,103
Net cash used in investing activities	-270,680	-704,902
Financing activities	'	'
Proceeds from common stock offering	'	668,553
Payment of offering costs	'	-27,423
Redemption of Series A preferred stock	'	-198,000
Payments of Debt Issuance Costs	3,101	7,172
Unsecured line of credit proceeds	732,000	687,000
Unsecured line of credit payments	-631,000	-785,000
Proceeds from Sale and Collection of Mortgage Notes Receivable	39,237	4,182
Principal payments on mortgage notes payable	-340,124	-112,837
Proceeds from Issuance of Other Long-term Debt	'	350,000
Proceeds from Issuance of Senior Long-term Debt	397,632	'
Proceeds from (Repayments of) Restricted Cash, Financing Activities	'	60,000
Distributions to operating partnership unit and LTIP unit holders	-4,175	-2,648
Dividends paid to common stockholders / unitholders	-144,289	-121,103
Dividends paid to preferred stockholders / unitholders	'	-6,045
Net cash provided by financing activities	46,180	509,507
Effect of exchange rate changes on cash and cash equivalents	-208	-53
Net increase / (decrease) in cash and cash equivalents	-842	9,254
Cash and cash equivalents at beginning of period	34,706	19,976
Cash and cash equivalents at end of period	33,864	29,230
Supplemental disclosure of cash flow information:	'	'
Cash paid during the period for interest (net of amounts capitalized of $15,734 and $9,999 during the nine months ended September 30, 2014 and 2013, respectively)	59,233	67,079
Supplemental disclosure of non-cash investing and financing activities:	'	'
Accrual for common stock dividends / unit distributions declared	49,363	45,145
Accrual for distributions declared for operating partnership unit and LTIP unit holders	1,351	1,273
Accrued additions to real estate and related intangible assets	113,704	60,246
Debt Instrument, Unamortized Premium	3,966	8,671
Equity issued in connection with Wexford Merger and 320 Charles Street acquisition	0	165,114
Notes Assumed	71,937	254,660
Stock Issued During Period, Value, Conversion of Convertible Securities	84,322	0
Equity issued in connection with 100 College Street and 300 George Street acquisition	$21,740	'

Organization_of_the_Parent_Com

Organization of the Parent Company and Description of Business	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	'
	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, through Wexford Science & Technology, LLC and related entities (collectively, "Wexford"), with universities and their related medical systems.
	The Parent Company is the sole general partner of the Operating Partnership and, as of September 30, 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.

Basis_of_Presentation_and_Summ

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Basis of Presentation and Summary of Significant Accounting Policies	'
	Basis of Presentation and Summary of Significant Accounting Policies
	The accompanying interim financial statements are unaudited, but have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and in conjunction with the rules and regulations of the U.S. Securities and Exchange Commission. Accordingly, they do not include all the disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments and eliminations, consisting of normal recurring adjustments necessary for a fair presentation of the financial statements for these interim periods have been recorded. These financial statements should be read in conjunction with the audited consolidated financial statements and notes therein included in the Company’s annual report on Form 10-K for the year ended December 31, 2013.
	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 three months ended September 30, 2014 and 2013, total revenues from properties outside the United States were $6.5 million and $4.5 million, respectively, which represented 3.8% and 2.8% of the Company's total revenues during the respective periods. For the nine months ended September 30, 2014 and 2013, total revenues from properties outside the United States were $16.1 million and $13.5 million, respectively, which represented 3.2% and 2.8% of the Company's total revenues during the respective periods. The Company’s net investments in properties outside the United States were $198.2 million and $190.2 million at September 30, 2014 and December 31, 2013, respectively.
	Investments in Partnerships and Limited Liability Companies
	The Company has determined that it is the primary beneficiary in six VIEs (excluding certain VIEs associated with tax credits discussed below), consisting of properties in which a tenant has a fixed-price purchase option, which are consolidated and reflected in the accompanying consolidated financial statements. Selected financial data of these VIEs at September 30, 2014 and December 31, 2013 consist of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Investment in real estate, net	$	437,927		$	336,832
	Total assets	498,975			375,443
	Total debt	190,878			143,067
	Total liabilities	204,323			154,953
	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 the benefits of historic tax credits (“HTCs”) and/or new market tax credits (“NMTCs”) for certain properties owned by Wexford. At September 30, 2014, Wexford owned nine properties 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 Company has determined that the special purpose entities are VIEs, since there is insufficient capital to finance their activities without further subordinated financial support. The Company has determined that it is the primary beneficiary of these VIEs, because it has the authority to direct the activities which most significantly impact their economic performance.
	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 income. At September 30, 2014, approximately $4.4 million of put liabilities were included in other liabilities in the consolidated balance sheets. The remaining balance of the TCI’s capital contribution is initially recorded in other liabilities in the consolidated balance sheets and is reclassified, upon delivery of the tax credit to the TCI, to reduce the carrying value of the subject property, net of allocated expenses. Direct and incremental costs incurred in structuring the transaction, consisting of third-party legal, accounting and other professional fees 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. During the nine months ended September 30, 2014, $22.6 million of tax credits, net of costs and estimated put payments, were contributed by TCIs and recorded as other liabilities in the consolidated balance sheets and $29.2 million in tax credits were delivered to the TCIs and reclassified as a reduction of the carrying value of the subject property.
	The Company has determined that certain special purpose entities owning properties 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 September 30, 2014 and December 31, 2013 consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Investment in real estate, net	$	200,536		$	177,901
	Total assets	217,889			198,968
	Total liabilities	67,636			60,197
	Investments in Real Estate, Net
	Investments in real estate, net consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Land	$	701,977		$	713,955
	Land under development	158,389			119,325
	Buildings and improvements	5,018,091			4,854,175
	Construction in progress	595,273			316,025
		6,473,730			6,003,480
	Accumulated depreciation	(938,615		)	(785,578		)
		$	5,535,115		$	5,217,902
	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. As of and for the three and nine months ended September 30, 2014, no assets have been identified as impaired and no such impairment losses have been recognized.
	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 September 30, 2014. Deferred leasing costs also include the net carrying value of acquired in-place leases and acquired management agreements.
	Deferred leasing costs, net at September 30, 2014 consisted of the following (in thousands):
		Balance at			Accumulated
		September 30, 2014			Amortization			Net
	Acquired in-place leases	$	416,366		$	(262,123	)	$	154,243
	Acquired management agreements	25,801			(21,540		)	4,261
	Deferred leasing and other direct costs	102,848			(36,528		)	66,320
		$	545,015		$	(320,191	)	$	224,824
	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
	Investments
	Investments in equity securities, which are included in other assets on the accompanying consolidated balance sheets, consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Available-for-sale securities, historical cost	$	7,297		$	8,543
	Unrealized gain, net	22,109			11,023
	Available-for-sale securities, fair-value (1)	29,406			19,566
	Privately-held securities, cost basis	30,929			18,485
	Total equity securities	$	60,335		$	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. 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 are based upon the closing trading price of the equity security as of the balance sheet date. At September 30, 2014, none of these investments have fair-values less than the Company’s cost basis, net of previous other-than-temporary impairment. However, 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 nine months ended September 30, 2014, the Company recorded a $1.3 million impairment charge, which is included in other expense in the consolidated statements of income. The impairment charge related to the Company’s investment in a privately-held company. Other than this investment 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 nine months ended September 30, 2014 on the Company’s remaining cost basis investments.
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 (the "Construction Loan"). 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 sheets. 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 three and nine months ended September 30, 2014, the Company recorded lease termination revenue, net of write-offs of lease intangibles, included in other revenue on the consolidated statements of income of approximately $3.3 million and $9.8 million, respectively. Lease termination revenue for the three months ended September 30, 2014 primarily related to the early termination of leases at two of the Company's properties. For the nine months ended September 30, 2014, lease termination revenue also included the early termination of leases at the Company's 4570 Executive Drive property. During the three and nine months ended September 30, 2013, the Company recorded lease termination revenue, net of write-offs of lease intangibles, included in other revenue on the consolidated statements of income of approximately $1.5 million and $42.8 million, respectively. Lease termination revenue for the nine months ended September 30, 2013 primarily related to the termination of a lease with Elan Corporation at the Company’s Science Center at Oyster Point property for which Elan paid the Company $46.5 million. The impact of the Elan lease termination was recognized through the date of the termination of the lease in April 2013.
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.

Equity_of_the_Parent_Company

Equity of the Parent Company	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Equity of the Parent Company	'
	Equity of the Parent Company
	During the nine months ended September 30, 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 7,702 shares were forfeited during the same period), which are included in the total of common stock outstanding as of the period end.
	During the three months ended September 30, 2014, at the request of the holders that exercised their exchange right pursuant to the terms of the Operating Partnership's Exchangeable Senior Notes due 2030 (the "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.
	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 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, 7,243 shares of which were surrendered to the Company and subsequently retired in lieu of cash payments for taxes due on the vesting of the Performance Units) 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 ended December 31, 2013. During the nine months ended September 30, 2014, the Parent Company awarded 494,410 Performance Units which represent the maximum number of Performance Units that may vest and which vest over a three-year Performance Period. The grant date fair-value of these awards of approximately $3.8 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 nine months ended September 30, 2014 to be expensed in future periods over a weighted-average term of approximately 2.3 years was $2.9 million as of September 30, 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 September 30, 2014, the Company had outstanding 197,455,157 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 nine months ended September 30, 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
	Changes in Accumulated Other Comprehensive Loss by Component
	The following table shows the changes in accumulated other comprehensive loss for the Parent Company for the nine months ended September 30, 2014, by component (in thousands):
		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	(484		)		20,300				(3,426		)		16,390
	Amounts reclassified from accumulated other comprehensive income (1)	—				(9,322		)		7,729				(1,593		)
	Net other comprehensive (loss) / income	$	(484	)		$	10,978			$	4,303			$	14,797
	Net other comprehensive loss / (income) allocable to noncontrolling interests	13				(2,689		)		(113		)		(2,789		)
	Balance as of September 30, 2014	$	3,434			$	17,227			$	(41,576	)		$	(20,915	)
	-1	Amounts reclassified from unrealized gain on available-for-sale securities are included in other income, net in the consolidated statements of income. Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of income. See Note 9 for further information on derivative instruments.
	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 September 30, 2014, was approximately $110.8 million based on the average closing price of the Parent Company’s common stock of $20.50 per share for the ten consecutive trading days immediately preceding September 30, 2014.
	The following table shows the vested ownership interests in the Operating Partnership:
		September 30, 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	196,034,482			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	201,307,515			100	%		195,959,961			100	%

Capital_of_the_Operating_Partn

Capital of the Operating Partnership	9 Months Ended
	Sep. 30, 2014
Partners' Capital [Abstract]	'
Capital of the Operating Partnership	'
	Capital of the Operating Partnership
	Operating Partnership Units and LTIP Units
	As of September 30, 2014, the Operating Partnership had outstanding 202,538,557 operating partnership units and 322,074 LTIP units. The Parent Company owned 97.4% of the partnership interests in the Operating Partnership at September 30, 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.
	The redemption value of the OP units owned by the limited partners, not including the Parent Company, had such units been redeemed at September 30, 2014, was approximately $110.8 million based on the average closing price of the Parent Company’s common stock of $20.50 per share for the ten consecutive trading days immediately preceding September 30, 2014.
	Changes in Accumulated Other Comprehensive Loss by Component
	The following table shows the changes in accumulated other comprehensive loss for the Operating Partnership for the nine months ended September 30, 2014, by component (in thousands):
		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	(484		)	20,300			$	(3,426	)	16,390
	Amounts reclassified from accumulated other comprehensive income (1)	—			(9,322		)	$	7,729		(1,593		)
	Net other comprehensive (loss) / income	$	(484	)	$	10,978		$	4,303		$	14,797
	Net other comprehensive income allocable to noncontrolling interest	—			(2,461		)	—			(2,461		)
	Balance as of September 30, 2014	$	3,522		$	17,703		$	(39,552	)	$	(18,327	)
	-1	Amounts reclassified from unrealized gain on available-for-sale securities are included in other income, net in the consolidated statements of income. Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of income. See Note 9 for further information on derivative instruments.

Debt

Debt	9 Months Ended
	Sep. 30, 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, 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 September 30, 2014 and December 31, 2013 (dollars in thousands):
		Stated Interest Rate		Effective Interest Rate		Principal Balance
						September 30,			December 31,			Maturity Date
						2014			2013
	Mortgage Notes Payable
	9900 Belward Campus Drive	5.64	%	3.99	%	$	10,523		$	10,631		July 1, 2017
	9901 Belward Campus Drive	5.64	%	3.99	%	12,959			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	%	61,224			—			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	%	45,481			—			July 1, 2025
	Hershey Center for Applied Research	6.15	%	4.71	%	13,072			13,449			May 5, 2027
	500 Kendall Street (Kendall D)	6.38	%	5.45	%	56,155			57,927			December 1, 2018
	Shady Grove Road	5.97	%	5.97	%	141,631			143,067			September 1, 2016
	University of Maryland BioPark I	5.93	%	4.69	%	16,237			16,752			May 15, 2025
	University of Maryland BioPark II	5.2	%	4.33	%	62,170			62,946			September 5, 2021
	University of Maryland BioPark Garage	5.2	%	4.33	%	4,679			4,738			September 1, 2021
	University of Miami Life Science & Technology Park	4	%	2.89	%	20,000			20,000			February 1, 2016
						465,131			698,048
	Unamortized premiums					13,412			11,276
	Mortgage notes payable, net					478,543			709,324
	Exchangeable Senior Notes	3.75	%	3.75	%	95,678			180,000			January 15, 2030
	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					(6,428		)	(4,917		)
	Unsecured senior notes, net					1,293,572			895,083
	Term Loan due 2017 - U.S. dollar (3)	1.55	%	2.38	%	243,596			243,596			March 30, 2017
	Term Loan due 2017 - GBP (3)	1.9	%	2.14	%	162,280			165,190			March 30, 2017
	Term Loan due 2018	1.35	%	1.67	%	350,000			350,000			March 24, 2018
	Unsecured senior term loans					755,876			758,786
	Unsecured line of credit (4)	1.25	%	1.25	%	229,000			128,000			March 24, 2018
	Total consolidated debt					$	2,852,669		$	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 $1.62 to £1.00 and $1.65 to £1.00 at September 30, 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 September 30, 2014, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $671.0 million.
	Exchangeable Senior Notes
	During the three months ended September 30, 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.
	Notes due 2019
	On April 23, 2014, the Operating Partnership issued $400.0 million aggregate principal amount of its Notes due 2019. 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. The Notes due 2019 bear interest at 2.625% per annum, priced at 99.408% of the principal amount to yield 2.752% to maturity. Interest is payable on May 1 and November 1 of each year beginning November 1, 2014 until the maturity date of May 1, 2019. The Operating Partnership’s obligations under the Notes due 2019 are fully and unconditionally guaranteed by the Parent Company.
	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 September 30, 2014, principal payments due for the Operating Partnership’s consolidated indebtedness (excluding debt premiums and discounts) were as follows (in thousands):
	2014	$	2,080
	2015	31,784
	2016	629,632
	2017	438,182
	2018	626,804
	Thereafter (1)	1,117,203
		$	2,845,685
	-1	Includes approximately $95.7 million in remaining principal payments of the Exchangeable Senior Notes based on a contractual maturity date of January 15, 2030.

Earnings_Per_Share_of_the_Pare

Earnings Per Share of the Parent Company	9 Months Ended
	Sep. 30, 2014
Earnings Per Share, Basic and Diluted [Abstract]	'
Earnings Per Share of the Parent Company	'
	Earnings Per Share of the Parent Company
	Through September 30, 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 three and nine months ended September 30, 2014 and 2013 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 three and nine months ended September 30, 2014 and 2013 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 three and nine months ended September 30, 2014 and 2013, the Performance Units were dilutive to the calculation of diluted earnings per share as calculated, assuming that September 30, 2014 and 2013 were the end dates of the respective Performance Units' Performance Periods. For the three and nine months ended September 30, 2014 and 2013, 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. Additionally, 7,589,600 and 9,571,008 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 for the three and nine months ended September 30, 2014, respectively. For the three and nine months ended September 30, 2013, 10,405,224 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 for each period. No other shares were considered anti-dilutive for the three and nine months ended September 30, 2014 or 2013.
	Computations of basic and diluted earnings per share (in thousands, except share data) were as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Basic earnings per share:
	Net income	$	16,976		$	4,136		$	56,841		$	36,633
	Net (income) / loss attributable to noncontrolling interests	(1,016		)	111			(3,412		)	(268		)
	Preferred stock dividends	—			—			—			(2,393		)
	Cost on redemption of preferred stock	—			—			—			(6,531		)
	Net income allocable and distributions in excess of earnings to participating securities	(375		)	(333		)	(1,130		)	(989		)
	Net income available to common stockholders - basic	$	15,585		$	3,914		$	52,299		$	26,452
	Diluted earnings per share:
	Net income available to common stockholders - basic	15,585			3,914			52,299			26,452
	Net income attributable to noncontrolling interests in Operating Partnership	429			118			1,464			534
	Net income available to common stockholders - diluted	$	16,014		$	4,032		$	53,763		$	26,986
	Weighted-average common shares outstanding:
	Basic	194,022,619			190,646,722			191,988,661			179,138,169
	Incremental shares from:
	Performance units	146,800			68,947			255,607			71,699
	Operating partnership and LTIP units	5,405,474			5,415,974			5,407,089			3,911,372
	Diluted	199,574,893			196,131,643			197,651,357			183,121,240
	Basic and diluted earnings per share:
	Net income per share available to common stockholders - basic and diluted	$	0.08		$	0.02		$	0.27		$	0.15

Earnings_Per_Unit_of_the_Opera

Earnings Per Unit of the Operating Partnership	9 Months Ended
	Sep. 30, 2014
Partnership Income [Abstract]	'
Earnings Per Unit of the Operating Partnership	'
	Earnings Per Unit of the Operating Partnership
	Through September 30, 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 three and nine months ended September 30, 2014 and 2013, has been deducted from net income available to unitholders to calculate basic earnings per unit. For the three and nine months ended September 30, 2014 and 2013, 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 was calculated based upon net income attributable to unitholders. For the three and nine months ended September 30, 2014 and 2013, the Performance Units were dilutive to the calculation of diluted earnings per unit as calculated, assuming that September 30, 2014 and 2013 were the end dates of the respective Performance Units’ Performance Periods. Additionally, 7,589,600 and 9,571,008 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 for the three and nine months ended September 30, 2014, respectively. For the three and nine months ended September 30, 2013, 10,405,224 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 for each period. No other units were considered anti-dilutive for the three and nine months ended September 30, 2014 or 2013.
	Computations of basic and diluted earnings per unit (in thousands, except unit data) were as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Basic and diluted earnings per unit:
	Net income	$	16,976		$	4,136		$	56,841		$	36,633
	(Income) / loss attributable to noncontrolling interests	(587		)	229			(1,948		)	266
	Preferred unit distributions	—			—			—			(2,393		)
	Cost on redemption of preferred units	—			—			—			(6,531		)
	Net income allocable and distributions in excess of earnings to participating securities	(375		)	(333		)	(1,130		)	(993		)
	Net income available to unitholders - basic and diluted	$	16,014		$	4,032		$	53,763		$	26,982
	Weighted-average units outstanding:
	Basic	199,428,093			196,062,696			197,395,750			183,048,587
	Incremental units from:
	Performance units	146,800			68,947			255,607			71,699
	Diluted	199,574,893			196,131,643			197,651,357			183,120,286
	Basic and diluted earnings per unit:
	Net income per unit available to unitholders - basic and diluted	$	0.08		$	0.02		$	0.27		$	0.15

Investment_in_Unconsolidated_P

Investment in Unconsolidated Partnerships	9 Months Ended
	Sep. 30, 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 September 30, 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 September 30, 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 $11.9 million at September 30, 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):
		September 30,				December 31,
		2014				2013
	Assets:
	Investments in real estate, net	$	270,040			$	262,753
	Cash and cash equivalents (including restricted cash)	12,235				3,855
	Other assets	10,530				5,301
	Total assets	$	292,805			$	271,909
	Liabilities and members’ equity:
	Mortgage notes payable and secured loan	$	152,036			$	151,968
	Other liabilities	11,425				12,102
	Members’ equity	129,344				107,839
	Total liabilities and members' equity	$	292,805			$	271,909
	Company’s net investment in unconsolidated partnerships	$	36,275			$	32,137
	The selected data and condensed results of operations for the unconsolidated partnerships were as follows (in thousands):
			Three Months Ended							Nine Months Ended
			September 30,							September 30,
			2014				2013			2014			2013
	Total revenues		$	18,173			$	3,778		$	27,386		$	9,486
	Total expenses		(15,693		)		(5,328		)	(27,681		)	(16,013		)
	Net income / (loss)		$	2,480			$	(1,550	)	$	(295	)	$	(6,527	)
	Company’s equity in net income / (loss) of unconsolidated partnerships		$	733			$	(112	)	$	585		$	(697	)
	Fees earned by the Company (1)		$	140			$	35		$	678		$	121
	-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 income.

Derivatives_and_Other_Financia

Derivatives and Other Financial Instruments	9 Months Ended
	Sep. 30, 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.
	As of September 30, 2014, the Company had deferred interest costs of approximately $30.3 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, other derivatives and their respective fair-values (dollars in thousands):
												Fair-Value(1)
		Notional Amount										September 30,				December 31,
						Strike Rate			Effective Date	Expiration Date		2014				2013
	Interest rate swaps	$	200,000			1.163	%		March 30, 2012	March 30, 2017		$	(1,259	)		$	(1,876	)
	Interest rate swaps	200,000				0.701	%		October 1, 2013	October 1, 2016		(68		)		(288		)
	Interest rate swaps(2)	81,140				0.731	%		August 2, 2012	March 30, 2017		968				1,545
	Interest rate swaps(2)	81,140				0.7425	%		August 2, 2012	March 30, 2017		943				1,519
	Total interest rate swaps	$	562,280									584				900
	Other derivatives											118				416
	Total											$	702			$	1,316
	-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	Translations to U.S. dollars are based on exchange rates of $1.62 to £1.00 and $1.65 to £1.00 at September 30, 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 three and nine months ended September 30, 2014 and 2013, 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 three and nine months ended September 30, 2014 and 2013.
	The following is a summary of the amount of loss recognized in other comprehensive income related to the derivative instruments (in thousands):
			Three Months Ended							Nine Months Ended
			September 30,							September 30,
			2014				2013			2014				2013
	Amount of (loss) / income recognized in other comprehensive income (effective portion):
	Cash flow hedges
	Interest rate swaps		$	(726	)		$	(1,371	)	$	(3,426	)		$	2,653
	Amount of loss reclassified from accumulated other comprehensive loss to earnings(effective portion):
	Cash flow hedges
	Interest rate swaps (1)		$	895			$	600		$	2,677			$	1,752
	Forward starting swaps (2)		1,677				1,705			5,052				5,134
	Total interest rate swaps		$	2,572			$	2,305		$	7,729			$	6,886
	-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.
	During the next twelve months, the Company estimates that an additional $9.5 million will be reclassified from accumulated other comprehensive loss as an increase to interest expense.
	During the three and nine months ended September 30, 2014, the Company recorded total unrealized loss on derivative instruments of $190,000 and $298,000, respectively, related to changes in the fair-value of other derivative instruments, included in other income, net in the consolidated statements of income.

FairValue_of_Financial_Instrum

Fair-Value of Financial Instruments	9 Months Ended
	Sep. 30, 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 September 30, 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 fixed-rate 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 September 30, 2014 and December 31, 2013, the aggregate fair-value and the carrying value of the Company’s financial instruments were as follows (in thousands):
		September 30, 2014						December 31, 2013
		Fair-Value (1)			Carrying Value			Fair-Value (1)			Carrying Value
	Mortgage notes payable, net	$	484,685		$	478,543		$	730,394		$	709,324
	Exchangeable Senior Notes	113,259			95,678			202,626			180,000
	Notes due 2016, net	415,680			399,171			417,040			398,787
	Notes due 2019, net	414,800			397,785			—			—
	Notes due 2020, net	285,025			248,388			275,600			248,210
	Notes due 2022, net	256,000			248,227			240,400			248,086
	Term Loan due 2017 - U.S. dollar	243,000			243,596			244,751			243,596
	Term Loan due 2017 - GBP (2)	161,885			162,280			165,969			165,190
	Term Loan due 2018	346,431			350,000			350,000			350,000
	Unsecured line of credit	227,438			229,000			128,000			128,000
	Derivative instruments (3)	(702		)	(702		)	(1,316		)	(1,316		)
	Available-for-sale securities	29,406			29,406			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 $1.62 to £1.00 and $1.65 to £1.00 at September 30, 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	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Business Combination Disclosure	'
	Acquisitions
	The Company acquired the following properties during the nine months ended September 30, 2014. The table below reflects the preliminary purchase price allocation for these acquisitions (in thousands). The Company expects the purchase price allocations to be finalized within one year of the acquisition date.
	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 Center (3)	May 15, 2014	—		—		—			3,836		—		—			3,836
	Total		$	170,382	$	63	$	(3,926	)	$	3,836	$	51,047	$	(3,966	)	$	217,436
	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 is expected to be approximately $191.0 million, comprised of (1) approximately $89.0 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 (2) approximately $102.0 million of remaining construction costs. As of April 4, 2014, Winstanley Enterprises LLC and affiliates retained an approximate 25% noncontrolling interest. On June 3, 2014, Winstanley Enterprises LLC's 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’s 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 is expected to be approximately $24.4 million.
	Revenues of approximately $4.7 million and net loss of approximately $40,000 associated with properties acquired in 2014 listed above are included in the consolidated statements of income for the three months ended September 30, 2014 for both the Parent Company and the Operating Partnership.
	Revenues of approximately $9.2 million and net loss of approximately $318,000 associated with properties acquired in 2014 listed above are included in the consolidated statements of income for the nine months ended September 30, 2014 for both the Parent Company and the Operating Partnership.

Basis_of_Presentation_and_Summ1

Basis of Presentation and Summary of Significant Accounting Policies (Policy)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
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 three months ended September 30, 2014 and 2013, total revenues from properties outside the United States were $6.5 million and $4.5 million, respectively, which represented 3.8% and 2.8% of the Company's total revenues during the respective periods. For the nine months ended September 30, 2014 and 2013, total revenues from properties outside the United States were $16.1 million and $13.5 million, respectively, which represented 3.2% and 2.8% of the Company's total revenues during the respective periods. The Company’s net investments in properties outside the United States were $198.2 million and $190.2 million at September 30, 2014 and December 31, 2013, respectively.
Investments in Partnerships and Limited Liability Companies	'
	Investments in Partnerships and Limited Liability Companies
	The Company has determined that it is the primary beneficiary in six VIEs (excluding certain VIEs associated with tax credits discussed below), consisting of properties in which a tenant has a fixed-price purchase option, which are consolidated and reflected in the accompanying consolidated financial statements. Selected financial data of these VIEs at September 30, 2014 and December 31, 2013 consist of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Investment in real estate, net	$	437,927		$	336,832
	Total assets	498,975			375,443
	Total debt	190,878			143,067
	Total liabilities	204,323			154,953
	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 the benefits of historic tax credits (“HTCs”) and/or new market tax credits (“NMTCs”) for certain properties owned by Wexford. At September 30, 2014, Wexford owned nine properties 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 Company has determined that the special purpose entities are VIEs, since there is insufficient capital to finance their activities without further subordinated financial support. The Company has determined that it is the primary beneficiary of these VIEs, because it has the authority to direct the activities which most significantly impact their economic performance.
	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 income. At September 30, 2014, approximately $4.4 million of put liabilities were included in other liabilities in the consolidated balance sheets. The remaining balance of the TCI’s capital contribution is initially recorded in other liabilities in the consolidated balance sheets and is reclassified, upon delivery of the tax credit to the TCI, to reduce the carrying value of the subject property, net of allocated expenses. Direct and incremental costs incurred in structuring the transaction, consisting of third-party legal, accounting and other professional fees 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. During the nine months ended September 30, 2014, $22.6 million of tax credits, net of costs and estimated put payments, were contributed by TCIs and recorded as other liabilities in the consolidated balance sheets and $29.2 million in tax credits were delivered to the TCIs and reclassified as a reduction of the carrying value of the subject property.
	The Company has determined that certain special purpose entities owning properties 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 September 30, 2014 and December 31, 2013 consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Investment in real estate, net	$	200,536		$	177,901
	Total assets	217,889			198,968
	Total liabilities	67,636			60,197
Investments in Real Estate, Net	'
	Investments in Real Estate, Net
	Investments in real estate, net consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Land	$	701,977		$	713,955
	Land under development	158,389			119,325
	Buildings and improvements	5,018,091			4,854,175
	Construction in progress	595,273			316,025
		6,473,730			6,003,480
	Accumulated depreciation	(938,615		)	(785,578		)
		$	5,535,115		$	5,217,902
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. As of and for the three and nine months ended September 30, 2014, no assets have been identified as impaired and no such impairment losses have been recognized.
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 September 30, 2014. Deferred leasing costs also include the net carrying value of acquired in-place leases and acquired management agreements.
	Deferred leasing costs, net at September 30, 2014 consisted of the following (in thousands):
		Balance at			Accumulated
		September 30, 2014			Amortization			Net
	Acquired in-place leases	$	416,366		$	(262,123	)	$	154,243
	Acquired management agreements	25,801			(21,540		)	4,261
	Deferred leasing and other direct costs	102,848			(36,528		)	66,320
		$	545,015		$	(320,191	)	$	224,824
	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
Investments	'
	Investments
	Investments in equity securities, which are included in other assets on the accompanying consolidated balance sheets, consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Available-for-sale securities, historical cost	$	7,297		$	8,543
	Unrealized gain, net	22,109			11,023
	Available-for-sale securities, fair-value (1)	29,406			19,566
	Privately-held securities, cost basis	30,929			18,485
	Total equity securities	$	60,335		$	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. 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 are based upon the closing trading price of the equity security as of the balance sheet date. At September 30, 2014, none of these investments have fair-values less than the Company’s cost basis, net of previous other-than-temporary impairment. However, 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 nine months ended September 30, 2014, the Company recorded a $1.3 million impairment charge, which is included in other expense in the consolidated statements of income. The impairment charge related to the Company’s investment in a privately-held company. Other than this investment 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 nine months ended September 30, 2014 on the Company’s remaining cost basis investments.
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 (the "Construction Loan"). 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 sheets. 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 three and nine months ended September 30, 2014, the Company recorded lease termination revenue, net of write-offs of lease intangibles, included in other revenue on the consolidated statements of income of approximately $3.3 million and $9.8 million, respectively. Lease termination revenue for the three months ended September 30, 2014 primarily related to the early termination of leases at two of the Company's properties. For the nine months ended September 30, 2014, lease termination revenue also included the early termination of leases at the Company's 4570 Executive Drive property. During the three and nine months ended September 30, 2013, the Company recorded lease termination revenue, net of write-offs of lease intangibles, included in other revenue on the consolidated statements of income of approximately $1.5 million and $42.8 million, respectively. Lease termination revenue for the nine months ended September 30, 2013 primarily related to the termination of a lease with Elan Corporation at the Company’s Science Center at Oyster Point property for which Elan paid the Company $46.5 million. The impact of the Elan lease termination was recognized through the date of the termination of the lease in April 2013.
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.

Basis_of_Presentation_and_Summ2

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Selected Financial Data of the VIEs	'
	The Company has determined that certain special purpose entities owning properties 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 September 30, 2014 and December 31, 2013 consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Investment in real estate, net	$	200,536		$	177,901
	Total assets	217,889			198,968
	Total liabilities	67,636			60,197
	Selected financial data of these VIEs at September 30, 2014 and December 31, 2013 consist of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Investment in real estate, net	$	437,927		$	336,832
	Total assets	498,975			375,443
	Total debt	190,878			143,067
	Total liabilities	204,323			154,953
Investments in Real Estate, Net	'
	Investments in real estate, net consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Land	$	701,977		$	713,955
	Land under development	158,389			119,325
	Buildings and improvements	5,018,091			4,854,175
	Construction in progress	595,273			316,025
		6,473,730			6,003,480
	Accumulated depreciation	(938,615		)	(785,578		)
		$	5,535,115		$	5,217,902
Deferred Leasing Costs, Net	'
	Deferred leasing costs, net at September 30, 2014 consisted of the following (in thousands):
		Balance at			Accumulated
		September 30, 2014			Amortization			Net
	Acquired in-place leases	$	416,366		$	(262,123	)	$	154,243
	Acquired management agreements	25,801			(21,540		)	4,261
	Deferred leasing and other direct costs	102,848			(36,528		)	66,320
		$	545,015		$	(320,191	)	$	224,824
	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
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):
		September 30,			December 31,
		2014			2013
	Available-for-sale securities, historical cost	$	7,297		$	8,543
	Unrealized gain, net	22,109			11,023
	Available-for-sale securities, fair-value (1)	29,406			19,566
	Privately-held securities, cost basis	30,929			18,485
	Total equity securities	$	60,335		$	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.

Equity_of_the_Parent_Company_T

Equity of the Parent Company (Tables)	9 Months Ended
	Sep. 30, 2014
Equity of the Parent Company	'
Dividends and Distributions	'
	The following table lists the dividends and distributions declared by the Parent Company and the Operating Partnership during the nine months ended September 30, 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
Changes in Accumulated Other Comprehensive Loss by Component	'
	Changes in Accumulated Other Comprehensive Loss by Component
	The following table shows the changes in accumulated other comprehensive loss for the Operating Partnership for the nine months ended September 30, 2014, by component (in thousands):
		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	(484		)		20,300				$	(3,426	)		16,390
	Amounts reclassified from accumulated other comprehensive income (1)	—				(9,322		)		$	7,729			(1,593		)
	Net other comprehensive (loss) / income	$	(484	)		$	10,978			$	4,303			$	14,797
	Net other comprehensive income allocable to noncontrolling interest	—				(2,461		)		—				(2,461		)
	Balance as of September 30, 2014	$	3,522			$	17,703			$	(39,552	)		$	(18,327	)
	-1	Amounts reclassified from unrealized gain on available-for-sale securities are included in other income, net in the consolidated statements of income. Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of income. See Note 9 for further information on derivative instruments.
Vested Ownership Interests	'
	The following table shows the vested ownership interests in the Operating Partnership:
		September 30, 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	196,034,482			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	201,307,515			100	%		195,959,961			100	%
Parent Company	'
Equity of the Parent Company	'
Changes in Accumulated Other Comprehensive Loss by Component	'
	The following table shows the changes in accumulated other comprehensive loss for the Parent Company for the nine months ended September 30, 2014, by component (in thousands):
		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	(484		)		20,300				(3,426		)		16,390
	Amounts reclassified from accumulated other comprehensive income (1)	—				(9,322		)		7,729				(1,593		)
	Net other comprehensive (loss) / income	$	(484	)		$	10,978			$	4,303			$	14,797
	Net other comprehensive loss / (income) allocable to noncontrolling interests	13				(2,689		)		(113		)		(2,789		)
	Balance as of September 30, 2014	$	3,434			$	17,227			$	(41,576	)		$	(20,915	)
	-1	Amounts reclassified from unrealized gain on available-for-sale securities are included in other income, net in the consolidated statements of income. Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of income. See Note 9 for further information on derivative instruments.

Capital_of_the_Operating_Partn1

Capital of the Operating Partnership Capital of the Operating Partnership (Tables)	9 Months Ended
	Sep. 30, 2014
Statement of Partners' Capital [Abstract]	'
Changes in Accumulated Other Comprehensive Loss by Component	'
	Changes in Accumulated Other Comprehensive Loss by Component
	The following table shows the changes in accumulated other comprehensive loss for the Operating Partnership for the nine months ended September 30, 2014, by component (in thousands):
		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	(484		)	20,300			$	(3,426	)	16,390
	Amounts reclassified from accumulated other comprehensive income (1)	—			(9,322		)	$	7,729		(1,593		)
	Net other comprehensive (loss) / income	$	(484	)	$	10,978		$	4,303		$	14,797
	Net other comprehensive income allocable to noncontrolling interest	—			(2,461		)	—			(2,461		)
	Balance as of September 30, 2014	$	3,522		$	17,703		$	(39,552	)	$	(18,327	)
	-1	Amounts reclassified from unrealized gain on available-for-sale securities are included in other income, net in the consolidated statements of income. Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of income. See Note 9 for further information on derivative instruments.

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2014 and December 31, 2013 (dollars in thousands):
		Stated Interest Rate		Effective Interest Rate		Principal Balance
						September 30,			December 31,			Maturity Date
						2014			2013
	Mortgage Notes Payable
	9900 Belward Campus Drive	5.64	%	3.99	%	$	10,523		$	10,631		July 1, 2017
	9901 Belward Campus Drive	5.64	%	3.99	%	12,959			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	%	61,224			—			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	%	45,481			—			July 1, 2025
	Hershey Center for Applied Research	6.15	%	4.71	%	13,072			13,449			May 5, 2027
	500 Kendall Street (Kendall D)	6.38	%	5.45	%	56,155			57,927			December 1, 2018
	Shady Grove Road	5.97	%	5.97	%	141,631			143,067			September 1, 2016
	University of Maryland BioPark I	5.93	%	4.69	%	16,237			16,752			May 15, 2025
	University of Maryland BioPark II	5.2	%	4.33	%	62,170			62,946			September 5, 2021
	University of Maryland BioPark Garage	5.2	%	4.33	%	4,679			4,738			September 1, 2021
	University of Miami Life Science & Technology Park	4	%	2.89	%	20,000			20,000			February 1, 2016
						465,131			698,048
	Unamortized premiums					13,412			11,276
	Mortgage notes payable, net					478,543			709,324
	Exchangeable Senior Notes	3.75	%	3.75	%	95,678			180,000			January 15, 2030
	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					(6,428		)	(4,917		)
	Unsecured senior notes, net					1,293,572			895,083
	Term Loan due 2017 - U.S. dollar (3)	1.55	%	2.38	%	243,596			243,596			March 30, 2017
	Term Loan due 2017 - GBP (3)	1.9	%	2.14	%	162,280			165,190			March 30, 2017
	Term Loan due 2018	1.35	%	1.67	%	350,000			350,000			March 24, 2018
	Unsecured senior term loans					755,876			758,786
	Unsecured line of credit (4)	1.25	%	1.25	%	229,000			128,000			March 24, 2018
	Total consolidated debt					$	2,852,669		$	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 $1.62 to £1.00 and $1.65 to £1.00 at September 30, 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 September 30, 2014, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $671.0 million.
Principal Payments Due for Operating Partnership's Consolidated Indebtedness	'
	As of September 30, 2014, principal payments due for the Operating Partnership’s consolidated indebtedness (excluding debt premiums and discounts) were as follows (in thousands):
	2014	$	2,080
	2015	31,784
	2016	629,632
	2017	438,182
	2018	626,804
	Thereafter (1)	1,117,203
		$	2,845,685
	-1	Includes approximately $95.7 million in remaining principal payments of the Exchangeable Senior Notes based on a contractual maturity date of January 15, 2030.

Earnings_Per_Share_of_the_Pare1

Earnings Per Share of the Parent Company (Tables)	9 Months Ended
	Sep. 30, 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:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Basic earnings per share:
	Net income	$	16,976		$	4,136		$	56,841		$	36,633
	Net (income) / loss attributable to noncontrolling interests	(1,016		)	111			(3,412		)	(268		)
	Preferred stock dividends	—			—			—			(2,393		)
	Cost on redemption of preferred stock	—			—			—			(6,531		)
	Net income allocable and distributions in excess of earnings to participating securities	(375		)	(333		)	(1,130		)	(989		)
	Net income available to common stockholders - basic	$	15,585		$	3,914		$	52,299		$	26,452
	Diluted earnings per share:
	Net income available to common stockholders - basic	15,585			3,914			52,299			26,452
	Net income attributable to noncontrolling interests in Operating Partnership	429			118			1,464			534
	Net income available to common stockholders - diluted	$	16,014		$	4,032		$	53,763		$	26,986
	Weighted-average common shares outstanding:
	Basic	194,022,619			190,646,722			191,988,661			179,138,169
	Incremental shares from:
	Performance units	146,800			68,947			255,607			71,699
	Operating partnership and LTIP units	5,405,474			5,415,974			5,407,089			3,911,372
	Diluted	199,574,893			196,131,643			197,651,357			183,121,240
	Basic and diluted earnings per share:
	Net income per share available to common stockholders - basic and diluted	$	0.08		$	0.02		$	0.27		$	0.15

Earnings_Per_Unit_of_the_Opera1

Earnings Per Unit of the Operating Partnership (Tables)	9 Months Ended
	Sep. 30, 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:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Basic and diluted earnings per unit:
	Net income	$	16,976		$	4,136		$	56,841		$	36,633
	(Income) / loss attributable to noncontrolling interests	(587		)	229			(1,948		)	266
	Preferred unit distributions	—			—			—			(2,393		)
	Cost on redemption of preferred units	—			—			—			(6,531		)
	Net income allocable and distributions in excess of earnings to participating securities	(375		)	(333		)	(1,130		)	(993		)
	Net income available to unitholders - basic and diluted	$	16,014		$	4,032		$	53,763		$	26,982
	Weighted-average units outstanding:
	Basic	199,428,093			196,062,696			197,395,750			183,048,587
	Incremental units from:
	Performance units	146,800			68,947			255,607			71,699
	Diluted	199,574,893			196,131,643			197,651,357			183,120,286
	Basic and diluted earnings per unit:
	Net income per unit available to unitholders - basic and diluted	$	0.08		$	0.02		$	0.27		$	0.15

Investment_in_Unconsolidated_P1

Investment in Unconsolidated Partnerships (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 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 September 30, 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 $11.9 million at September 30, 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):
		September 30,				December 31,
		2014				2013
	Assets:
	Investments in real estate, net	$	270,040			$	262,753
	Cash and cash equivalents (including restricted cash)	12,235				3,855
	Other assets	10,530				5,301
	Total assets	$	292,805			$	271,909
	Liabilities and members’ equity:
	Mortgage notes payable and secured loan	$	152,036			$	151,968
	Other liabilities	11,425				12,102
	Members’ equity	129,344				107,839
	Total liabilities and members' equity	$	292,805			$	271,909
	Company’s net investment in unconsolidated partnerships	$	36,275			$	32,137
Schedule of Selected Income Statement Information	'
	The selected data and condensed results of operations for the unconsolidated partnerships were as follows (in thousands):
			Three Months Ended							Nine Months Ended
			September 30,							September 30,
			2014				2013			2014			2013
	Total revenues		$	18,173			$	3,778		$	27,386		$	9,486
	Total expenses		(15,693		)		(5,328		)	(27,681		)	(16,013		)
	Net income / (loss)		$	2,480			$	(1,550	)	$	(295	)	$	(6,527	)
	Company’s equity in net income / (loss) of unconsolidated partnerships		$	733			$	(112	)	$	585		$	(697	)
	Fees earned by the Company (1)		$	140			$	35		$	678		$	121
	-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 income.

Derivatives_and_Other_Financia1

Derivatives and Other Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Summary of Derivative Instruments	'
	The following is a summary of the terms of the interest rate swaps, other derivatives and their respective fair-values (dollars in thousands):
												Fair-Value(1)
		Notional Amount										September 30,				December 31,
						Strike Rate			Effective Date	Expiration Date		2014				2013
	Interest rate swaps	$	200,000			1.163	%		March 30, 2012	March 30, 2017		$	(1,259	)		$	(1,876	)
	Interest rate swaps	200,000				0.701	%		October 1, 2013	October 1, 2016		(68		)		(288		)
	Interest rate swaps(2)	81,140				0.731	%		August 2, 2012	March 30, 2017		968				1,545
	Interest rate swaps(2)	81,140				0.7425	%		August 2, 2012	March 30, 2017		943				1,519
	Total interest rate swaps	$	562,280									584				900
	Other derivatives											118				416
	Total											$	702			$	1,316
	-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	Translations to U.S. dollars are based on exchange rates of $1.62 to £1.00 and $1.65 to £1.00 at September 30, 2014 and December 31, 2013, respectively.
Summary of Derivative Instruments, Effect on OCI	'
	The following is a summary of the amount of loss recognized in other comprehensive income related to the derivative instruments (in thousands):
			Three Months Ended							Nine Months Ended
			September 30,							September 30,
			2014				2013			2014				2013
	Amount of (loss) / income recognized in other comprehensive income (effective portion):
	Cash flow hedges
	Interest rate swaps		$	(726	)		$	(1,371	)	$	(3,426	)		$	2,653
	Amount of loss reclassified from accumulated other comprehensive loss to earnings(effective portion):
	Cash flow hedges
	Interest rate swaps (1)		$	895			$	600		$	2,677			$	1,752
	Forward starting swaps (2)		1,677				1,705			5,052				5,134
	Total interest rate swaps		$	2,572			$	2,305		$	7,729			$	6,886
	-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)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair-Value and Carrying Value of the Company's Financial Instruments	'
	At September 30, 2014 and December 31, 2013, the aggregate fair-value and the carrying value of the Company’s financial instruments were as follows (in thousands):
		September 30, 2014						December 31, 2013
		Fair-Value (1)			Carrying Value			Fair-Value (1)			Carrying Value
	Mortgage notes payable, net	$	484,685		$	478,543		$	730,394		$	709,324
	Exchangeable Senior Notes	113,259			95,678			202,626			180,000
	Notes due 2016, net	415,680			399,171			417,040			398,787
	Notes due 2019, net	414,800			397,785			—			—
	Notes due 2020, net	285,025			248,388			275,600			248,210
	Notes due 2022, net	256,000			248,227			240,400			248,086
	Term Loan due 2017 - U.S. dollar	243,000			243,596			244,751			243,596
	Term Loan due 2017 - GBP (2)	161,885			162,280			165,969			165,190
	Term Loan due 2018	346,431			350,000			350,000			350,000
	Unsecured line of credit	227,438			229,000			128,000			128,000
	Derivative instruments (3)	(702		)	(702		)	(1,316		)	(1,316		)
	Available-for-sale securities	29,406			29,406			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 $1.62 to £1.00 and $1.65 to £1.00 at September 30, 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)	9 Months Ended
	Sep. 30, 2014
Business Acquisition	'
Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	'
	Note 11. Acquisitions
	The Company acquired the following properties during the nine months ended September 30, 2014. The table below reflects the preliminary purchase price allocation for these acquisitions (in thousands). The Company expects the purchase price allocations to be finalized within one year of the acquisition date.
	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 Center (3)		May 15, 2014	—			—		—			3,836		—		—			3,836
	Total			$	170,382		$	63	$	(3,926	)	$	3,836	$	51,047	$	(3,966	)	$	217,436
	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 is expected to be approximately $191.0 million, comprised of (1) approximately $89.0 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 (2) approximately $102.0 million of remaining construction costs. As of April 4, 2014, Winstanley Enterprises LLC and affiliates retained an approximate 25% noncontrolling interest. On June 3, 2014, Winstanley Enterprises LLC's 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’s 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 is expected to be approximately $24.4 million.
Selected Financial Data of the VIEs	'
	The Company has determined that certain special purpose entities owning properties 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 September 30, 2014 and December 31, 2013 consisted of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Investment in real estate, net	$	200,536		$	177,901
	Total assets	217,889			198,968
	Total liabilities	67,636			60,197
	Selected financial data of these VIEs at September 30, 2014 and December 31, 2013 consist of the following (in thousands):
		September 30,			December 31,
		2014			2013
	Investment in real estate, net	$	437,927		$	336,832
	Total assets	498,975			375,443
	Total debt	190,878			143,067
	Total liabilities	204,323			154,953

Organization_of_the_Parent_Com1

Organization of the Parent Company and Description of Business (Details)	Sep. 30, 2014	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements	'	'
Equity Method Investment, Ownership Percentage	100.00%	100.00%
Remaining Ownership Interest Held by Limited Partners	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

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

VIEs

Foreign

Foreign

Foreign

Foreign

Foreign

Boston Development Project

Boston Development Project

Science Center at Oyster Point

Historic and New Market Tax Credits [Member]

Historic tax credit [Member]

New Market Tax Credits [Member]

Maximum [Member]

sqft

properties

Deferred Leasing and Other Direct Costs

Basis of Presentation and Summary of Significant Accounting Policies [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Finite-Lived Intangible Assets, Remaining Amortization Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'20 years

Syndicated Historic Tax Credits and New Market Tax Credits

'

'

'

'

'

'

'

'

'

'

'

'

'

9

'

'

'

Revenue from properties outside the United States, net

'

'

'

'

'

$6,500,000

$4,500,000

$16,100,000

$13,500,000

'

'

'

'

'

'

'

'

Percentage of Company's total revenue

'

'

'

'

'

3.80%

2.80%

3.20%

2.80%

'

'

'

'

'

'

'

'

Real Estate Investment Property, Net

5,535,115,000

'

5,535,115,000

'

5,217,902,000

198,200,000

'

198,200,000

'

190,200,000

'

'

'

'

'

'

'

Number of Variable Interest Entities that the Company is the Primary Beneficiary

'

'

6

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net

'

'

-1,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

BioMed Realty Trust Interest in Construction Loan

'

'

'

'

'

'

'

'

'

'

255,000,000

'

'

'

'

'

'

Construction Loan

'

'

'

'

'

'

'

'

'

'

355,000,000

'

'

'

'

'

'

Square Footage of Real Estate Property

'

'

'

'

'

'

'

'

'

'

1,100,000

'

'

'

'

'

'

Percent Leased

'

'

'

'

'

'

'

'

'

'

95.00%

'

'

'

'

'

'

Investment In Construction Loan

'

'

'

'

'

'

'

'

'

'

191,200,000

151,800,000

'

'

'

'

'

Lease Termination Revenue

3,300,000

1,500,000

9,800,000

42,800,000

'

'

'

'

'

'

'

'

46,500,000

'

'

'

'

Percentage Of Qualified Investments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

39.00%

'

'

Percentage Of Tax Credit Recapture

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20.00%

100.00%

'

Deferred Costs and Other Assets

4,400,000

'

4,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Tax credits, net of costs and estimated put paments

'

'

22,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Tax Credits Delivered

'

'

-29,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Prepayment Fee

'

'

'

'

'

'

'

'

'

'

8,100,000

'

'

'

'

'

'

Other revenue

'

'

'

'

'

'

'

'

'

'

$7,500,000

'

'

'

'

'

'

Basis_of_Presentation_and_Summ4

Basis of Presentation and Summary of Significant Accounting Policies (Selected Financial Data of the VIEs) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]	'	'
Investment in Real Estate, Net	$437,927	$336,832
Total Assets	498,975	375,443
Total Debt	190,878	143,067
Total Liabilities	$204,323	$154,953

Basis_of_Presentation_and_Summ5

Basis of Presentation and Summary of Significant Accounting Policies (Investments in Real Estate, Net) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]	'	'
Land	$701,977	$713,955
Land Under Development	158,389	119,325
Buildings and Improvements	5,018,091	4,854,175
Construction in Progress	595,273	316,025
Real Estate Investment Property, at Cost	6,473,730	6,003,480
Accumulated Depreciation	-938,615	-785,578
Real Estate Investment Property, Net	$5,535,115	$5,217,902

Basis_of_Presentation_and_Summ6

Basis of Presentation and Summary of Significant Accounting Policies (Deferred Leasing Costs, Net) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred Leasing Costs	'	'
Finite-Lived Intangible Assets, Gross	$545,015	$482,696
Finite-Lived Intangible Assets, Accumulated Amortization	-320,191	-284,629
Finite-Lived Intangible Assets, Net	224,824	198,067
Leases, Acquired-in-Place	'	'
Deferred Leasing Costs	'	'
Finite-Lived Intangible Assets, Gross	416,366	365,753
Finite-Lived Intangible Assets, Accumulated Amortization	-262,123	-233,935
Finite-Lived Intangible Assets, Net	154,243	131,818
Acquired Management Agreements	'	'
Deferred Leasing Costs	'	'
Finite-Lived Intangible Assets, Gross	25,801	25,801
Finite-Lived Intangible Assets, Accumulated Amortization	-21,540	-20,053
Finite-Lived Intangible Assets, Net	4,261	5,748
Deferred Leasing and Other Direct Costs	'	'
Deferred Leasing Costs	'	'
Finite-Lived Intangible Assets, Gross	102,848	91,142
Finite-Lived Intangible Assets, Accumulated Amortization	-36,528	-30,641
Finite-Lived Intangible Assets, Net	$66,320	$60,501

Basis_of_Presentation_and_Summ7

Basis of Presentation and Summary of Significant Accounting Policies (Investments) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]	'		'
Available-for-sale securities, historical cost	$7,297		$8,543
Unrealized gain, net	22,109		11,023
Available-for-sale securities, fair-value	29,406	[1]	19,566	[1]
Privately-held securities, cost basis	30,929		18,485
Total equity securities	$60,335		$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.

Basis_of_Presentation_and_Summ8

Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation and Summary of Significant Accounting Policies (Selected Financial Data and VIEs, Wexford) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity Carrying Amount Of Collateralized Investment In Real Estate Net	$437,927	$336,832
Variable Interest Entity, Consolidated, Carrying Amount, Assets	498,975	375,443
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	204,323	154,953
Wexford Merger [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity Carrying Amount Of Collateralized Investment In Real Estate Net	200,536	177,901
Variable Interest Entity, Consolidated, Carrying Amount, Assets	217,889	198,968
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$67,636	$60,197

Equity_of_the_Parent_Company_N

Equity of the Parent Company (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Mar. 31, 2012

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

BIOMED REALTY, L.P.

BIOMED REALTY, L.P.

Performance Shares

Performance Shares

Limited Partner

Limited Partner

Additional Paid-In Capital

Additional Paid-In Capital

Common Stock

Common Stock

Common Stock

Operating Partnership Units and LTIP Units

Restricted Stock Issued to Employees

Restricted stock issued to board members [Member]

Parent Company

Parent Company

BIOMED REALTY, L.P.

BIOMED REALTY, L.P.

Common Stock

Common Stock

Equity of the Parent Company

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted Stock Awards Issued

'

'

'

'

'

'

'

'

'

'

565,107

22,555

'

'

'

'

'

'

Shares surrendered to the Company and retired in lieu of cash payments for taxes due on the vesting of restricted stock

'

'

-218,663

'

'

'

'

'

'

'

'

'

'

'

'

-7,243

'

'

Shares forfeited during the period

'

'

7,702

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Issued During Period, Shares, Conversion of Convertible Securities

'

'

'

'

'

'

4,955,377

4,955,377

'

'

'

'

'

'

'

'

0

'

Stock Issued During Period, Value, Conversion of Convertible Securities

'

'

$84,322,000

$0

$84,322,000

'

'

'

'

'

'

'

$84,322,000

$0

'

'

$0

'

Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures

'

'

'

'

'

'

'

374,278

'

'

'

'

'

'

'

'

'

'

Performance units forfeited during the period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

116,072

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value

3,800,000

'

3,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition

'

'

'2 years 3 months

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value

2,900,000

'

2,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Performance units

'

'

'

'

'

'

'

'

'

'

'

'

'

'

136,296

494,410

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20,224

'

'

Stock Issued During Period, Value, New Issues

'

'

-49,000

'

'

-49,000

'

'

'

'

'

'

-49,000

'

'

'

'

'

Proceeds from Issuance of Common Stock

'

'

'

668,553,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common Stock, Shares Outstanding

'

'

'

'

'

'

197,455,157

197,455,157

192,115,002

'

'

'

'

'

'

'

'

'

Partnership Units, Shares Outstanding

'

'

'

'

'

'

'

'

'

5,083,400

'

'

'

'

'

'

5,405,474

5,415,974

LTIP Units, Shares Outstanding

'

'

'

'

'

'

'

'

'

322,074

'

'

'

'

'

'

'

'

Payments of Ordinary Dividends, Preferred Stock and Preference Stock

'

'

'

6,045,000

'

'

'

'

'

'

'

'

'

6,045,000

'

'

'

'

Cost on redemption of preferred stock / units

0

0

'

-6,531,000

'

'

'

'

'

'

'

'

'

-6,531,000

'

'

'

'

Noncontrolling Interest Redemption Value

$110,800,000

'

$110,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Average Closing Price Per Common Share

'

'

$20.50

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity_of_the_Parent_Company_D

Equity of the Parent Company (Dividends and Distributions) (Details) (USD $)	3 Months Ended			9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2013
	Common stock and OP units	Common stock and OP units	Common stock and OP units	Parent Company
Equity of the Parent Company	'	'	'	'
Declaration Date	15-Sep-14	16-Jun-14	17-Mar-14	'
Amount Per Common Share/Unit	$0.25	$0.25	$0.25	'
Dividend and Distribution Payable Date	15-Oct-14	15-Jul-14	15-Apr-14	'
Dividend and Distribution Amount	$50,714	$49,483	$49,479	'
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	'	'	'	$6,045

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) (Parent Company, USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Accumulated Other Comprehensive Income Loss [Line Items]	'	'	'		'	'
Accumulated other comprehensive loss, net	($20,915)	'	($20,915)		'	($32,923)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	16,390		'	'
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	3,009,710	'	3,009,710		'	2,987,025
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	'	'	20,300		'	'
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	'	'	5,052		'	'
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	'	'	-1,593	[1]	'	'
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	3,550	2,280	20,300		8,435	'
Other Comprehensive Income (Loss), Net of Tax	3,924	5,080	14,797		17,722	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	1,767	493	6,201		1,883	'
Accumulated Translation Adjustment [Member]	'	'	'		'	'
Accumulated Other Comprehensive Income Loss [Line Items]	'	'	'		'	'
Accumulated other comprehensive loss, net	3,434	'	3,434		'	3,905
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	-484		'	'
Other Comprehensive Income (Loss), Net of Tax	'	'	-484		'	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	'	'	13		'	'
Accumulated Other Comprehensive Income (Loss)	'	'	'		'	'
Accumulated Other Comprehensive Income Loss [Line Items]	'	'	'		'	'
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	-20,915	'	-20,915		'	-32,923
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	'	'	16,073		'	'
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	'	'	4,918		'	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	'	'	-2,789		'	'
Accumulated Net Unrealized Investment Gain (Loss) [Member]	'	'	'		'	'
Accumulated Other Comprehensive Income Loss [Line Items]	'	'	'		'	'
Accumulated other comprehensive loss, net	17,227	'	17,227		'	8,938
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	20,300		'	'
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	'	'	-9,322	[1]	'	'
Other Comprehensive Income (Loss), Net of Tax	'	'	10,978		'	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	'	'	-2,689		'	'
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'	'		'	'
Accumulated Other Comprehensive Income Loss [Line Items]	'	'	'		'	'
Accumulated other comprehensive loss, net	-41,576	'	-41,576		'	-45,766
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	'	'	7,729	[1]	'	'
Other Comprehensive Income (Loss), Net of Tax	'	'	4,303		'	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	'	'	-113		'	'
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Interest Rate Swaps	'	'	'		'	'
Accumulated Other Comprehensive Income Loss [Line Items]	'	'	'		'	'
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	($3,426)		'	'
[1]	Amounts reclassified from unrealized gain on available-for-sale securities are included in other income, net in the consolidated statements of income. Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of income. See Note 9 for further information on derivative instruments.

Equity_of_the_Parent_Company_V

Equity of the Parent Company (Vested Ownership Interests) (Details)	Sep. 30, 2014	Dec. 31, 2013
Equity of the Parent Company	'	'
Operating Partnership Units and LTIP Units	201,307,515	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	196,034,482	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 $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified			BIOMED REALTY, L.P.	BIOMED REALTY, L.P.	Parent Company	Parent Company	Parent Company	Parent Company
Capital of the Operating Partnership [Line Items]	'	'	'	'	'	'	'	'
Partners' Capital Account, Units	'	'	202,538,557	'	'	'	'	'
LTIP Units, Shares Outstanding	'	'	322,074	'	'	'	'	'
Equity Method Investment, Ownership Percentage	100.00%	100.00%	'	'	'	'	97.40%	97.30%
Noncontrolling Interest Redemption Value	'	'	'	'	$110.80	$110.80	'	'
Average Closing Price Per Common Share	'	'	'	'	'	$20.50	'	'
Noncontrolling Interest Redemption Value Calculation Days	'	'	'	'10 days	'10 days	'	'	'

Capital_of_the_Operating_Partn3

Capital of the Operating Partnership Capital of the Operating Partnership (Changes in Accumulated Other Comprehensive Loss by Component) (Details) (BIOMED REALTY, L.P., USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Capital of the Operating Partnership [Line Items]	'	'	'		'	'
Accumulated other comprehensive loss, net	($18,327)	'	($18,327)		'	($30,663)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	16,390		'	'
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	'	'	-1,593	[1]	'	'
Other Comprehensive Income (Loss), Net of Tax	3,924	5,080	14,797		17,722	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	1,253	-229	4,409		-266	'
Accumulated Translation Adjustment [Member]	'	'	'		'	'
Capital of the Operating Partnership [Line Items]	'	'	'		'	'
Accumulated other comprehensive loss, net	3,522	'	3,522		'	4,006
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	-484		'	'
Other Comprehensive Income (Loss), Net of Tax	'	'	-484		'	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	'	'	0		'	'
Accumulated Net Unrealized Investment Gain (Loss) [Member]	'	'	'		'	'
Capital of the Operating Partnership [Line Items]	'	'	'		'	'
Accumulated other comprehensive loss, net	17,703	'	17,703		'	9,186
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	20,300		'	'
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	'	'	-9,322	[1]	'	'
Other Comprehensive Income (Loss), Net of Tax	'	'	10,978		'	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	'	'	-2,461		'	'
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'	'		'	'
Capital of the Operating Partnership [Line Items]	'	'	'		'	'
Accumulated other comprehensive loss, net	-39,552	'	-39,552		'	-43,855
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	-3,426		'	'
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	'	'	7,729	[1]	'	'
Other Comprehensive Income (Loss), Net of Tax	'	'	4,303		'	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	'	'	0		'	'
Accumulated Other Comprehensive Income (Loss)	'	'	'		'	'
Capital of the Operating Partnership [Line Items]	'	'	'		'	'
Comprehensive (Income) Loss, Net of Tax, Attributable to Noncontrolling Interest	'	'	($2,461)		'	'
[1]	Amounts reclassified from unrealized gain on available-for-sale securities are included in other income, net in the consolidated statements of income. Amounts reclassified from loss on derivative instruments are included in interest expense, net in the consolidated statements of income. See Note 9 for further information on derivative instruments.

Debt_Debt_Narrative_Details

Debt Debt (Narrative) (Details) (USD $)

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Sep. 30, 2014

Apr. 23, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

In Thousands, except Share data, unless otherwise specified

Exchangeable Senior Notes

Exchangeable Senior Notes

Mortgage Notes Payable

Mortgage Notes Payable

Unsecured Line of Credit

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 Due 2018 [Member]

Unsecured Term Loan Due 2018 [Member]

Unsecured Term Loans

Unsecured Term Loans

Unsecured Senior Notes Due Twenty Nineteen [Member]

Unsecured Senior Notes Due Twenty Nineteen [Member]

Unsecured Senior Notes Due Twenty Nineteen [Member]

Unsecured Senior Notes Due Twenty Twenty [Member]

Unsecured Senior Notes Due Twenty Twenty-Two [Member]

Unsecured Senior Notes Due Twenty Sixteen [Member]

ThreeHundredGeorgeStreet [Member]

OneHundredCollegeStreet [Member]

OneHundredCollegeStreet [Member]

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

Parent Company

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 Debt [Member]

Unsecured Debt [Member]

Mortgage Notes Payable

Mortgage Notes Payable

Mortgage Notes Payable

Common Stock

Common Stock

Additional Paid-In Capital

Debt Instruments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Convertible Debt

'

$95,678

$180,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$95,678

'

$180,000

'

'

'

Foreign Currency Exchange Rate, Translation

'

'

'

'

'

'

'

'

1.62

1.65

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Interest Rate, Stated Percentage

'

3.75%

'

'

'

1.25%

[1]

'

'

'

'

1.90%

[2]

'

1.35%

'

1.55%

[2]

'

'

2.63%

2.63%

6.13%

4.25%

3.85%

6.20%

2.40%

'

'

'

'

'

'

'

Percentage Of Long Term Debt Principal Paid By Underwriters

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

99.41%

'

'

'

'

'

'

'

'

'

'

'

'

Effective Interest Rate

'

3.75%

'

'

'

1.25%

[1]

'

'

'

'

2.14%

[2]

'

1.67%

'

2.38%

[2]

'

'

2.72%

2.75%

6.27%

4.36%

3.99%

4.91%

2.40%

'

'

'

'

'

'

'

Debt Instrument Payable Dates

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

' May 1 and November 1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Date of First Required Payment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1-Nov-14

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Maturity Date

'

15-Jan-30

'

'

'

24-Mar-18

[1]

'

'

'

'

30-Mar-17

[2]

'

24-Mar-18

'

30-Mar-17

[2]

'

1-May-19

1-May-19

'

15-Apr-20

15-Jul-22

15-Apr-16

1-Jul-25

2-Aug-16

'

'

'

'

'

'

'

Principal Balance

2,845,685

'

'

465,131

698,048

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

45,481

61,224

0

'

'

'

'

'

'

Unsecured Term Loans

'

'

'

'

'

'

755,876

758,786

'

'

162,280

[2]

165,190

[2]

350,000

350,000

243,596

[2]

243,596

[2]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock Issued During Period, Shares, Other

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,955,377

4,955,377

'

Stock Issued During Period, Value, Conversion of Convertible Securities

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

84,322

0

'

'

'

84,322

Debt Instrument, Issuance Date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

23-Apr-14

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Face Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$400,000

'

'

'

'

'

'

'

'

'

'

'

'

[1]

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 $1.62 to £1.00 and $1.65 to £1.00 at SeptemberB 30, 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).

[2]

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)

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Sep. 30, 2014

Apr. 23, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

USD ($)

USD ($)

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 Senior Notes

Unsecured Senior Notes

Unsecured Term Loans

Unsecured Term Loans

Unsecured Line of Credit

Unsecured Line of Credit

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

OneHundredCollegeStreet [Member]

OneHundredCollegeStreet [Member]

4320 Forest Park Avenue

4320 Forest Park Avenue

ThreeHundredGeorgeStreet [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 Nineteen [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 ($)

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

GBP [Member]

USD ($)

USD ($)

USD ($)

GBP (£)

Debt Instruments

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'

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'

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'

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'

'

'

'

'

'

'

Stated Interest Rate

'

'

'

'

5.64%

'

5.64%

'

7.75%

'

2.40%

'

4.00%

'

6.20%

6.15%

'

6.38%

'

5.97%

'

5.93%

[1]

'

5.20%

[1]

'

5.20%

[1]

'

4.00%

[1]

'

3.75%

'

'

'

3.85%

'

'

2.63%

2.63%

6.13%

'

4.25%

'

'

'

1.25%

[2]

'

'

1.55%

[3]

'

'

'

1.90%

[3]

'

'

'

1.35%

'

Effective Interest Rate

'

'

'

'

3.99%

'

3.99%

'

7.75%

'

2.40%

'

2.70%

'

4.91%

4.71%

'

5.45%

'

5.97%

'

4.69%

[1]

'

4.33%

[1]

'

4.33%

[1]

'

2.89%

[1]

'

3.75%

'

'

'

3.99%

'

'

2.72%

2.75%

6.27%

'

4.36%

'

'

'

1.25%

[2]

'

'

2.38%

[3]

'

'

'

2.14%

[3]

'

'

'

1.67%

'

Principal Balance

$2,845,685,000

'

$465,131,000

$698,048,000

$10,523,000

$10,631,000

$12,959,000

$13,091,000

'

$334,447,000

$61,224,000

$0

$21,000,000

$21,000,000

$45,481,000

$13,072,000

$13,449,000

$56,155,000

$57,927,000

$141,631,000

$143,067,000

$16,237,000

[1]

$16,752,000

[1]

$62,170,000

[1]

$62,946,000

[1]

$4,679,000

[1]

$4,738,000

[1]

$20,000,000

[1]

$20,000,000

[1]

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unamortized Premiums

'

'

13,412,000

11,276,000

'

'

'

'

'

'

'

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'

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'

'

Mortgage Notes Payable, net

'

'

478,543,000

709,324,000

'

'

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Exchangeable Senior Notes

'

'

'

'

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'

'

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'

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'

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'

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'

'

'

95,678,000

180,000,000

'

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'

'

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'

'

'

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'

'

'

'

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'

'

Unsecured Senior Notes

'

'

'

'

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'

'

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'

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'

'

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

'

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Unamortized Discounts

'

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'

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-6,428,000

-4,917,000

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Unsecured Senior Notes, net

'

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'

1,293,572,000

895,083,000

'

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Unsecured Term Loans

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'

'

'

755,876,000

758,786,000

'

'

'

243,596,000

[3]

243,596,000

[3]

'

'

162,280,000

[3]

165,190,000

[3]

156,400,000

[3]

100,000,000

[3]

350,000,000

350,000,000

Unsecured Line of Credit

'

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229,000,000

[2]

128,000,000

[2]

'

'

'

'

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'

'

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'

'

Total Consolidated Debt

2,852,669,000

2,671,193,000

'

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Maturity Date

'

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'

1-Jul-17

'

1-Jul-17

'

30-Jun-14

'

2-Aug-16

'

30-Jun-15

'

1-Jul-25

5-May-27

'

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

1-May-19

'

15-Apr-20

'

15-Jul-22

'

'

'

24-Mar-18

[2]

'

'

30-Mar-17

[3]

'

'

'

30-Mar-17

[3]

'

'

'

24-Mar-18

'

Foreign Currency Exchange Rate, Translation

'

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1.62

1.65

'

'

'

'

'

'

LOC Remaining Borrowing Capacity

'

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$671,000,000

'

'

'

'

'

'

'

'

'

'

[1]

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

[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 $1.62 to £1.00 and $1.65 to £1.00 at SeptemberB 30, 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_Principal_Payments_Due_fo

Debt (Principal Payments Due for Operating Partnership's Consolidated Indebtedness) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Year 1	$2,080		'
Year 2	31,784		'
Year 3	629,632		'
Year 4	438,182		'
Year 5	626,804		'
Thereafter	1,117,203	[1]	'
Principal Balance	2,845,685		'
Exchangeable Senior Notes	'		'
Exchangeable senior notes	$95,678		$180,000
Maturity Date	15-Jan-30		'
[1]	Includes approximately $95.7 million in remaining principal payments of the Exchangeable Senior Notes based on a contractual maturity date of JanuaryB 15, 2030.

Earnings_Per_Share_of_the_Pare2

Earnings Per Share of the Parent Company (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
BIOMED REALTY, L.P.	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	'	'	'	'
Exchangeable Senior Notes Due 2030	7,589,600	10,405,224	9,571,008	10,405,224
Parent Company	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	'	'	'	'
Exchangeable Senior Notes Due 2030	7,589,600	'	9,571,008	10,405,224

Earnings_Per_Share_of_the_Pare3

Earnings Per Share of the Parent Company (Schedule of Earnings Per Share, Basic and Diluted) (Details) (Parent Company, USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Parent Company	'	'	'	'
Schedule of Earnings Per Share Basic and Diluted	'	'	'	'
Income from continuing operations and noncontrolling interests	$16,976	$4,136	$56,841	$36,633
Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest	-1,016	111	-3,412	-268
Preferred Stock Dividends and Other Adjustments	'	'	'	-2,393
Cost On Redemption Of Preferred Stock	0	0	'	-6,531
Participating Securities, Distributed and Undistributed Earnings	-375	-333	-1,130	-989
Net Income (Loss) Available to Common Stockholders, Basic	15,585	3,914	52,299	26,452
Income (loss) from continuing operations attributable to noncontrollinginterests diluted	429	118	1,464	534
Net Income (Loss) Available to Common Stockholders, Diluted	$16,014	$4,032	$53,763	$26,986
Weighted Average Number of Shares Outstanding, Basic	194,022,619	190,646,722	191,988,661	179,138,169
Amount of Dilutive Securities Performance Units	146,800	68,947	255,607	71,699
Amount Of Dilutive Securities Operating Partnership And Ltip Units	5,405,474	5,415,974	5,407,089	3,911,372
Basic and Diluted	199,574,893	196,131,643	197,651,357	183,121,240
Earnings Per Share, Basic and Diluted	$0.08	$0.02	$0.27	$0.15

Earnings_Per_Unit_of_the_Opera2

Earnings Per Unit of the Operating Partnership Earnings Per Unit of the Operating Partnership (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Parent Company	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	'	'	'	'
Exchangeable Senior Notes Due 2030	7,589,600	'	9,571,008	10,405,224
BIOMED REALTY, L.P.	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share	'	'	'	'
Exchangeable Senior Notes Due 2030	7,589,600	10,405,224	9,571,008	10,405,224

Earnings_Per_Unit_of_the_Opera3

Earnings Per Unit of the Operating Partnership (Computations of Basic and Diluted Earnings Per Unit) (Details) (BIOMED REALTY, L.P., USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
BIOMED REALTY, L.P.	'	'	'	'
Earnings Per Unit of the Operating Partnership	'	'	'	'
Income from continuing operations and noncontrolling interests	$16,976	$4,136	$56,841	$36,633
Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest	-587	229	-1,948	266
Preferred Stock Dividends and Other Adjustments	'	'	'	-2,393
Cost On Redemption Of Preferred Stock	'	'	'	-6,531
Participating Securities, Distributed and Undistributed Earnings	-375	-333	-1,130	-993
Net Income Loss Attributable To Unit Holders Basic and Diluted	$16,014	$4,032	$53,763	$26,982
Weighted Average Number of Shares Outstanding, Basic	199,428,093	196,062,696	197,395,750	183,048,587
Amount of Dilutive Securities Performance Units	146,800	68,947	255,607	71,699
Basic and Diluted	199,574,893	196,131,643	197,651,357	183,120,286
Net Income per Unit Attributable to Unitholders, Basic and Diluted	$0.08	$0.02	$0.27	$0.15

Investment_in_Unconsolidated_P2

Investment in Unconsolidated Partnerships (Narrative) (Details)	Sep. 30, 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 $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014		Sep. 30, 2014	Sep. 30, 2014		Sep. 30, 2014
In Millions, unless otherwise specified			PREI I LLC		PREI II LLC	McKellar Court		BioPark Fremont
			properties
Investment In Unconsolidated Partnerships	'	'	'		'	'		'
Equity Method Investment, Ownership Percentage	100.00%	100.00%	20.00%	[1]	20.00%	22.00%	[2]	50.00%
Company's Economic Interest	'	'	20.00%	[1]	20.00%	22.00%	[2]	50.00%
Date Acquired	'	'	4-Apr-07	[1]	4-Apr-07	30-Sep-04	[2]	31-May-13
Number Of Properties In Portfolio Of Prei I Llc	'	'	2		'	'		'
Line of Credit Facility, Amount Outstanding	'	'	$139		'	'		'
Line Of Credit Facility Weighted Average Interest Rate	'	'	2.21%		'	'		'
Line of Credit Facility, Expiration Date	'	'	13-Aug-15		'	'		'
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	'	'	'		'	$11.90		'
Percent Of Extraordinary Cash Flow Entitled From Variable Interest Entity	'	'	'		'	75.00%		'
Percent Of Operating Cash Flows Entitled From Variable Interest Entity	'	'	'		'	22.00%		'
[1]	PREI I LLC owns two properties in Cambridge, Massachusetts. At SeptemberB 30, 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 $11.9 million at SeptemberB 30, 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.

Investment_in_Unconsolidated_P4

Investment in Unconsolidated Partnerships (Summary of Selected Balance Sheet Information) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Equity Method Investments and Joint Ventures [Abstract]	'	'
Investments in real estate, net	$270,040	$262,753
Cash and cash equivalents (including restricted cash)	12,235	3,855
Other assets	10,530	5,301
Total assets	292,805	271,909
Mortgage notes payable and secured loan	152,036	151,968
Other liabilities	11,425	12,102
Members' equity	129,344	107,839
Total liabilities and equity	292,805	271,909
Company's net investment in unconsolidated partnerships	$36,275	$32,137

Investment_in_Unconsolidated_P5

Investment in Unconsolidated Partnerships (Summary of Selected Income Statement Information) (Details) (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Equity Method Investments and Joint Ventures [Abstract]	'		'		'		'
Total revenues	$18,173		$3,778		$27,386		$9,486
Total expenses	-15,693		-5,328		-27,681		-16,013
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	2,480		-1,550		-295		-6,527
Company's equity in net loss of unconsolidated partnerships	733		-112		585		-697
Fees earned by the Company	$140	[1]	$35	[1]	$678	[1]	$121	[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 income.

Derivatives_and_Other_Financia2

Derivatives and Other Financial Instruments (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Derivative	'	'	'		'
Derivative, Deferred Interest Costs Amortization Period	'	'	'4 years		'
Other Income	$2,572,000	$2,305,000	$7,729,000		$6,886,000
Derivative, Gain (Loss) on Derivative, Net	-190,000	'	-298,000		'
Forward Starting Swaps	'	'	'		'
Derivative	'	'	'		'
Derivative, Deferred Interest Costs	30,300,000	'	30,300,000		'
Derivative, Lower Remaining Maturity Range	'	'	'10 years		'
Other Income	1,677,000	1,705,000	5,052,000	[1]	5,134,000
Interest Rate Swaps	'	'	'		'
Derivative	'	'	'		'
Derivative, Notional Amount	562,280,000	'	562,280,000		'
Other Income	895,000	600,000	2,677,000	[2]	1,752,000
Interest Rate Swaps - $200M [Member] | Interest Rate Swaps	'	'	'		'
Derivative	'	'	'		'
Derivative, Maturity Date	'	'	30-Mar-17		'
Derivative, Inception Date	'	'	30-Mar-12		'
Derivative, Notional Amount	200,000,000	'	200,000,000		'
Interest Rate Swaps - $200M (2) | Interest Rate Swaps	'	'	'		'
Derivative	'	'	'		'
Derivative, Maturity Date	'	'	1-Oct-16		'
Derivative, Inception Date	'	'	1-Oct-13		'
Derivative, Notional Amount	200,000,000	'	200,000,000		'
Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'		'
Derivative	'	'	'		'
Other Comprehensive Income (Loss), Net of Tax	'	'	$9,500,000		'
[1]	Amount represents reclassifications of deferred interest costs from accumulated other comprehensive loss to interest expense related to the Companybs previously settled forward starting swaps.
[2]	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).

Derivatives_and_Other_Financia3

Derivatives and Other Financial Instruments (Summary of Derivative Instruments) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Derivative	'		'
Derivative, Fair Value, Net	$702	[1]	$1,316	[1]
Unsecured Term Loan Due 2017 GBP Portion	'		'
Derivative	'		'
Foreign Currency Exchange Rate, Translation	1.62		1.65
Interest Rate Swaps	'		'
Derivative	'		'
Derivative, Notional Amount	562,280		'
Derivative, Fair Value, Net	584	[1]	900	[1]
Interest Rate Swaps | Interest Rate Swaps - $200M (1)	'		'
Derivative	'		'
Derivative, Notional Amount	200,000		'
Derivative, Fixed Interest Rate	1.16%		'
Derivative, Effective Date	30-Mar-12		'
Derivative, Maturity Date	30-Mar-17		'
Derivative, Fair Value, Net	-1,259	[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	1-Oct-13		'
Derivative, Maturity Date	1-Oct-16		'
Derivative, Fair Value, Net	-68	[1]	-288	[1]
Interest Rate Swaps | Interest Rate Swap - 50M GBP (1)	'		'
Derivative	'		'
Derivative, Notional Amount	81,140	[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	968	[1],[2]	1,545	[1],[2]
Interest Rate Swaps | Interest Rate Swap - 50M GBP (2)	'		'
Derivative	'		'
Derivative, Notional Amount	81,140	[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	943	[1],[2]	1,519	[1],[2]
Interest Rate Swaps | Other Derivatives [Domain]	'		'
Derivative	'		'
Derivative, Fair Value, Net	$118	[1]	$416	[1]
[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]	Translations to U.S. dollars are based on exchange rates of $1.62 to £1.00 and $1.65 to £1.00 at SeptemberB 30, 2014 and DecemberB 31, 2013, respectively.

Derivatives_and_Other_Financia4

Derivatives and Other Financial Instruments (Summary of Derivative Instruments, Effect on OCI) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Derivative	'	'	'		'
Other Income	$2,572	$2,305	$7,729		$6,886
Interest Rate Swaps	'	'	'		'
Derivative	'	'	'		'
Other Income	895	600	2,677	[1]	1,752
Forward Starting Swaps	'	'	'		'
Derivative	'	'	'		'
Other Income	1,677	1,705	5,052	[2]	5,134
Parent Company	'	'	'		'
Derivative	'	'	'		'
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	'	'	16,390		'
Parent Company | Interest Rate Swaps	'	'	'		'
Derivative	'	'	'		'
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	-726	-1,371	'		2,653
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	'	'	($3,426)		'
[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 Companybs previously settled forward starting swaps.

FairValue_of_Financial_Instrum2

Fair-Value of Financial Instruments (Fair-Value and Carrying Value of the Company's Financial Instruments) (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Fair-Value of Financial Instruments	'		'
Available-for-sale securities	$29,406	[1]	$19,566	[1]
Unsecured Term Loan Due 2017 GBP Portion	'		'
Fair-Value of Financial Instruments	'		'
Foreign Currency Exchange Rate, Translation	1.62		1.65
Mortgage Notes Payable	'		'
Fair-Value of Financial Instruments	'		'
Mortgage notes payable, net	478,543		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	1,293,572		895,083
Unsecured Line of Credit	'		'
Fair-Value of Financial Instruments	'		'
Unsecured line of credit	229,000	[2]	128,000	[2]
Fair-Value	'		'
Fair-Value of Financial Instruments	'		'
Available-for-sale securities	29,406	[3]	19,566	[3]
Fair-Value | Mortgage Notes Payable	'		'
Fair-Value of Financial Instruments	'		'
Mortgage notes payable, net	484,685	[3]	730,394	[3]
Fair-Value | Exchangeable Senior Notes	'		'
Fair-Value of Financial Instruments	'		'
Exchangeable senior notes	113,259	[3]	202,626	[3]
Fair-Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Sixteen [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior notes, net	415,680	[3]	417,040	[3]
Fair-Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Nineteen [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior notes, net	414,800	[3]	'
Fair-Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Twenty [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior notes, net	285,025	[3]	275,600	[3]
Fair-Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Twenty-Two [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior notes, net	256,000	[3]	240,400	[3]
Fair-Value | Unsecured Term Loans | Unsecured Term Loan USD Portion [Member] | USD	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior term loans	243,000	[3]	244,751	[3]
Fair-Value | Unsecured Term Loans | Unsecured Term Loan Due 2017 GBP Portion | GBP [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior term loans	161,885	[3],[4]	165,969	[3],[4]
Fair-Value | Unsecured Term Loans | Unsecured Term Loan Due 2018 [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior term loans	346,431	[3]	350,000	[3]
Fair-Value | Unsecured Line of Credit	'		'
Fair-Value of Financial Instruments	'		'
Unsecured line of credit	227,438	[3]	128,000	[3]
Carrying Value	'		'
Fair-Value of Financial Instruments	'		'
Derivative Instruments	-702	[3],[5]	-1,316	[3],[5]
Available-for-sale securities	29,406		19,566
Carrying Value | Mortgage Notes Payable	'		'
Fair-Value of Financial Instruments	'		'
Mortgage notes payable, net	478,543		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	399,171		398,787
Carrying Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Nineteen [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior notes, net	397,785		'
Carrying Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Twenty [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior notes, net	248,388		248,210
Carrying Value | Unsecured Senior Notes | Unsecured Senior Notes Due Twenty Twenty-Two [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior notes, net	248,227		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 [Member]	'		'
Fair-Value of Financial Instruments	'		'
Unsecured senior term loans	162,280	[4]	165,190	[4]
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	$229,000		$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]	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 $1.62 to £1.00 and $1.65 to £1.00 at SeptemberB 30, 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]	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.
[4]	The principal balance represents the U.S. dollar amount based on the exchange rate of $1.62 to £1.00 and $1.65 to £1.00 at SeptemberB 30, 2014 and DecemberB 31, 2013, respectively.
[5]	The Companybs 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_Narrative_Details

Acquisitions (Narrative) (Details) (USD $)

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Apr. 04, 2014

Sep. 30, 2014

Dec. 31, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

OneHundredCollegeStreet [Member]

ThreeHundredGeorgeStreet [Member]

FourThirty Cambridge Science Center [Member]

BIOMED REALTY, L.P.

BIOMED REALTY, L.P.

BIOMED REALTY, L.P.

BIOMED REALTY, L.P.

Winstanley Enterprises LLC [Domain]

Winstanley Enterprises LLC [Domain]

Winstanley Enterprises LLC [Domain]

Winstanley Enterprises LLC [Domain]

Parent Company

Parent Company

Parent Company

Parent Company

sqft

sqft

sqft

OneHundredCollegeStreet [Member]

OneHundredCollegeStreet [Member]

ThreeHundredGeorgeStreet [Member]

Scenario, Forecast [Member]

OneHundredCollegeStreet [Member]

Business Acquisition

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Area of Real Estate Property

'

510,419

[1]

518,940

[1]

42,410

[1]

'

'

'

'

'

'

'

'

'

'

'

'

Expected Total Project Investment

'

$191,000,000

'

$24,400,000

'

'

'

'

'

'

'

'

'

'

'

'

Business Combination, Separately Recognized Transactions, Revenues and Gains Recognized

'

'

'

'

4,700,000

'

9,200,000

'

'

'

'

'

4,700,000

'

9,200,000

'

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net

'

89,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

remaining construction costs

'

102,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition, Effective Date of Acquisition

'

4-Apr-14

[1]

4-Apr-14

[2]

15-May-14

[3]

'

'

'

'

'

'

'

'

'

'

'

'

Noncontrolling Interest in Limited Partnerships

2.60%

'

'

'

'

'

'

'

7.00%

25.00%

7.00%

3.00%

'

'

'

'

BusinessAcquisitionPurchasePriceAllocationMortgageNotesPayable

'

'

46,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Revenues

'

'

'

'

168,916,000

159,232,000

508,953,000

479,321,000

'

'

'

'

168,916,000

159,232,000

508,953,000

479,321,000

Net income / (loss)

'

'

'

'

($40,000)

'

($318,000)

'

'

'

'

'

($40,000)

'

($318,000)

'

[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 is expected to be approximately $191.0 million, comprised of (1) approximately $89.0 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 (2) approximately $102.0 million of remaining construction costs. As of AprilB 4, 2014, Winstanley Enterprises LLC and affiliates retained an approximate 25% noncontrolling interest. On June 3, 2014, Winstanley Enterprises LLC's 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 LLCbs 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 is expected to be approximately $24.4 million.

Acquisitions_Schedule_of_Purch

Acquisitions (Schedule of Purchase Price Allocation) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014
Business Acquisition	'
Business Acquisition, Purchase Price Allocation, Property	$170,382
Business Acquisition, Cost of Acquired Entity, Cash Paid	217,436
OneHundredCollegeStreet [Member]	'
Business Acquisition	'
Business Acquisition, Description of Acquired Entity	'100 College Street (1)	[1]
Business Acquisition, Effective Date of Acquisition	4-Apr-14	[1]
Business Acquisition, Purchase Price Allocation, Property	63,361	[1]
Business Acquisition, Cost of Acquired Entity, Cash Paid	96,600	[1]
ThreeHundredGeorgeStreet [Member]	'
Business Acquisition	'
Business Acquisition, Description of Acquired Entity	'300 George Street (2)	[2]
Business Acquisition, Effective Date of Acquisition	4-Apr-14	[2]
Business Acquisition, Purchase Price Allocation, Property	107,021	[2]
Business Acquisition, Cost of Acquired Entity, Cash Paid	117,000	[2]
FourThirty Cambridge Science Center [Member]	'
Business Acquisition	'
Business Acquisition, Description of Acquired Entity	'430 Cambridge Science Center (3)	[3]
Business Acquisition, Effective Date of Acquisition	15-May-14	[3]
Business Acquisition, Cost of Acquired Entity, Cash Paid	3,836	[3]
Above Market Leases [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	63
Finite-Lived Intangible Asset, Useful Life	'21 months
Above Market Leases [Member] | ThreeHundredGeorgeStreet [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	63	[2]
Leases, Acquired-in-Place, Market Adjustment	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	-3,926
Finite-Lived Intangible Asset, Useful Life	'143 months
Leases, Acquired-in-Place, Market Adjustment | ThreeHundredGeorgeStreet [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	-3,926	[2]
Acquired Below Market Ground Leases [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	3,836
Finite-Lived Intangible Asset, Useful Life	'1500 months
Acquired Below Market Ground Leases [Member] | FourThirty Cambridge Science Center [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	3,836	[3]
Leases, Acquired-in-Place	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	51,047
Finite-Lived Intangible Asset, Useful Life	'159 months
Leases, Acquired-in-Place | OneHundredCollegeStreet [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	33,239	[1]
Leases, Acquired-in-Place | ThreeHundredGeorgeStreet [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	17,808	[2]
Acquired Debt Premium [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	-3,966
Finite-Lived Intangible Asset, Useful Life	'135 months
Acquired Debt Premium [Member] | ThreeHundredGeorgeStreet [Member]	'
Business Acquisition	'
Acquired Finite-lived Intangible Asset, Amount	($3,966)	[2]
[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 is expected to be approximately $191.0 million, comprised of (1) approximately $89.0 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 (2) approximately $102.0 million of remaining construction costs. As of AprilB 4, 2014, Winstanley Enterprises LLC and affiliates retained an approximate 25% noncontrolling interest. On June 3, 2014, Winstanley Enterprises LLC's 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 LLCbs 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 is expected to be approximately $24.4 million.