Investment in Unconsolidated Partnerships (Narrative) (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010	Jun. 30, 2011		Jun. 30, 2010	Dec. 31, 2010
Investments in unconsolidated partnerships	$ 55,313,000			$ 55,313,000			$ 57,265,000
Promissory note, maturity date				Jul. 13, 2015	[1]
PREI Joint Ventures [Member]
LOC amount outstanding	203,300,000			203,300,000
LOC Expiration date				February 10, 2012
LOC contractual interest rate				3.69%
McKellar Court [Member]
Maximum exposure to loss on investment	12,400,000			12,400,000
Percent of extraordinary cash flow entitled to company				75.00%
Percent of operating cash flows entitled to company				22.00%
McKellar Court [Member]
Percentage of the operating cash flows	22.00%			22.00%
BIOMED REALTY TRUST, INC. [Member]
Investments in unconsolidated partnerships	55,313,000			55,313,000			57,265,000
Construction and development management fees	244,000		392,000	514,000		919,000
PREI I LLC
LOC amount outstanding	205,600,000			205,600,000
LOC Expiration date				August 13, 2011
LOC contractual interest rate				1.69%
Percentage of the operating cash flows	20.00%	[2]		20.00%	[2]
PREI II LLC
Investments in unconsolidated partnerships	$ 818,000			$ 818,000
Percentage of the operating cash flows	20.00%	[3]		20.00%	[3]

[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] PREI I LLC owns a portfolio of six properties in Cambridge, Massachusetts comprised of laboratory/office buildings. At June 30, 2011, there were $203.3 million in outstanding borrowings on the PREI joint ventures' secured acquisition and interim loan facility, with a contractual interest rate of 3.69% (including the applicable credit spread) which matures on February 10, 2012. At maturity, the PREI joint ventures may refinance the secured acquisition and interim loan facility, depending on market conditions and the availability of credit, or they may repay the principal balance through capital contributions of the members. At June 30, 2011, there were $205.6 million in outstanding borrowings on the secured construction loan facility entered into by a wholly owned subsidiary of the Company's joint venture with PREI I LLC, with a contractual interest rate of 1.69% (including the applicable credit spread) which matures on August 13, 2011. At maturity, the wholly owned subsidiary may refinance the loan, depending on market conditions and the availability of credit, or it may repay the principal balance of the construction loan through capital contributions of the members.

[3] The Company's remaining investment in PREI II LLC (maximum exposure to losses) was approximately $818,000 at June 30, 2011.