Debt (Outstanding Consolidated Mortgage Notes Payable) (Details) (USD $)	6 Months Ended
	Jun. 30, 2011		Dec. 31, 2010
Stated Fixed Interest Rate	1.29%	[1]
Effective Interest Rate	1.29%	[1]
Principal balance	$ 619,049,000		$ 652,317,000
Maturity Date	Jul. 13, 2015	[1]
Unamortized premiums	4,072,000		5,605,000
Mortgage notes payable, net	623,121,000		657,922,000
Exchangeable senior notes, net	199,706,000		199,522,000
Unsecured senior notes, net	645,246,000		247,571,000
Unsecured line of credit	121,200,000	[1]	392,450,000	[1]
Total consolidated debt	1,589,273,000		1,497,465,000
Carrying value of equity component recognized	14,000,000
Secured Term Loan [Member]
LOC remaining borrowing capacity	591,000,000
Outstanding letters of credit	7,800,000
New Unsecured Line Of Credit [Member]
Maturity Date	Jul. 13, 2015
LOC current borrowing capacity	750,000,000
Exchangeable Notes Due 2026, Net [Member]
Principal balance	19,800,000
Maturity Date	Oct. 01, 2026
Exchangeable Notes Due 2026, Net [Member]
Stated Fixed Interest Rate	4.50%
Effective Interest Rate	6.45%
Principal balance	19,800,000		19,800,000
Maturity Date	Oct. 01, 2026
Exchangeable senior notes, net	19,706,000	[2]	19,522,000	[2]
Unamortized discount	(94,000)	[3]	(278,000)	[3]
Exchangeable Senior Notes Due 2030 [Member]
Principal balance	180,000,000
Maturity Date	Jan. 15, 2030
Exchangeable Senior Notes Due 2030 [Member]
Stated Fixed Interest Rate	3.75%
Effective Interest Rate	3.75%
Principal balance	180,000,000		180,000,000
Maturity Date	Jan. 15, 2030
Ardentech Court [Member]
Stated Fixed Interest Rate	7.25%	[4]
Effective Interest Rate	5.06%	[4]
Principal balance		[4]	4,237,000	[4]
Maturity Date	Jul. 01, 2012	[4]
Center for Life Science|Boston [Member]
Stated Fixed Interest Rate	7.75%
Effective Interest Rate	7.75%
Principal balance	343,896,000		345,577,000
Maturity Date	Jun. 30, 2014
500 Kendall Street (Kendall D) [Member]
Stated Fixed Interest Rate	6.38%
Effective Interest Rate	5.45%
Principal balance	63,261,000		64,230,000
Maturity Date	Dec. 01, 2018
6828 Nancy Ridge Drive [Member]
Stated Fixed Interest Rate	7.15%
Effective Interest Rate	5.38%
Principal balance	6,430,000		6,488,000
Maturity Date	Sep. 01, 2012
Road to the Cure [Member]
Stated Fixed Interest Rate	6.70%	[4]
Effective Interest Rate	5.78%	[4]
Principal balance		[4]	14,696,000	[4]
Maturity Date	Jan. 31, 2014	[4]
10255 Science Center Drive [Member]
Stated Fixed Interest Rate	7.65%	[4]
Effective Interest Rate	5.04%	[4]
Principal balance		[4]	10,800,000	[4]
Maturity Date	Jul. 01, 2011	[4]
Shady Grove Road [Member]
Stated Fixed Interest Rate	5.97%
Effective Interest Rate	5.97%
Principal balance	147,000,000		147,000,000
Maturity Date	Sep. 01, 2016
Sidney Street [Member]
Stated Fixed Interest Rate	7.23%
Effective Interest Rate	5.11%
Principal balance	26,907,000		27,395,000
Maturity Date	Jun. 01, 2012
Sorrento West LLC [Member]
Stated Fixed Interest Rate	7.42%
Effective Interest Rate	2.72%
Principal balance	13,112,000		13,247,000
Maturity Date	Nov. 10, 2011
9865 Towne Centre Drive [Member]
Stated Fixed Interest Rate	7.95%	[5]
Effective Interest Rate	7.95%	[5]
Principal balance	17,528,000	[5]	17,636,000	[5]
Maturity Date	Jun. 30, 2013	[5]
Prepayment of mortgage loan	17,900,000
Prepayment of secured debt premium	351,000
900 Uniqema Boulevard [Member]
Stated Fixed Interest Rate	8.61%
Effective Interest Rate	5.61%
Principal balance	915,000		1,011,000
Maturity Date	May 01, 2015
Unsecured Senior Notes Due 2016, Net [Member]
Stated Fixed Interest Rate	3.85%
Effective Interest Rate	3.99%
Principal balance	400,000,000
Maturity Date	Apr. 15, 2016
Unsecured senior notes, net	397,576,000
Unamortized discount	(2,424,000)	[6]		[6]
Unsecured Senior Notes Due 2020, Net [Member]
Stated Fixed Interest Rate	6.13%
Effective Interest Rate	6.27%
Principal balance	250,000,000		250,000,000
Maturity Date	Apr. 15, 2020
Unsecured senior notes, net	247,670,000		247,571,000
Unamortized discount	(2,330,000)	[7]	(2,429,000)	[7]
Ardentech Court, Road To The Cure, And One Zero Two Five Five Science Center Drive Properties [Member]
Prepayment of mortgage loan	30,100,000
BIOMED REALTY TRUST, INC. [Member]
Mortgage notes payable, net	623,121,000		657,922,000
Exchangeable senior notes, net	199,706,000		199,522,000
Unsecured senior notes, net	645,246,000		247,571,000
Unsecured line of credit	$ 121,200,000		$ 392,450,000

[1] At June 30, 2011, the Operating Partnership had additional borrowing capacity under the unsecured line of credit of up to approximately $591.0 million (net of outstanding letters of credit issued by the Operating Partnership and drawable on the unsecured line of credit of approximately $7.8 million). On July 14, 2011, the Operating Partnership entered into a new $750.0 million unsecured line of credit, replacing its existing line of credit, as described below in this Note 5.

[2] As of June 30, 2011 and December 31, 2010, the carrying value of the equity component recognized was approximately $14.0 million.

[3] The unamortized debt discount will be amortized through October 1, 2011, the first date at which the holders of the Notes due 2026 may require the Operating Partnership to repurchase the Notes due 2026.

[4] During the six months ended June 30, 2011, the Operating Partnership voluntarily prepaid in full the outstanding mortgage notes totaling approximately $30.1 million pertaining to the Ardentech Court, Road to the Cure, and 10255 Science Center Drive properties, prior to their respective maturity dates.

[5] In July 2011, the Operating Partnership voluntarily prepaid in full the outstanding mortgage note pertaining to the 9865 Towne Centre Drive property, in the amount of approximately $17.9 million including a prepayment premium of $351,000, prior to its maturity date.

[6] The unamortized debt discount will be amortized through April 15, 2016, the maturity date of the Notes due 2016.

[7] The unamortized debt discount will be amortized through April 15, 2020, the maturity date of the Notes due 2020.