Acquisitions of Real Estate Property (Details 4) (Lillibridge Acquisition, USD $) In Millions, unless otherwise specified	1 Months Ended
Jul. 31, 2010 property party	Jul. 01, 2010 party
Business acquisition
Number of Medical office buildings	96
Purchase price of acquisition of assets		$ 381.0
Assumption of mortgage debt		79.5
Number of institutional third parties holding majority interests of joint ventures		2
Repaid mortgage debt involved in acquisition		$ 132.7
38 MOBs
Business acquisition
Number of Medical office buildings	38
Acquired ownership interest in Lillibridge's services and development business (as a percent)		100.00%
24 MOBs
Business acquisition
Number of Medical office buildings	24
Acquired ownership interest in Lillibridge's services and development business (as a percent)		20.00%
34 MOBs
Business acquisition
Number of Medical office buildings	34
Acquired ownership interest in Lillibridge's services and development business (as a percent)		5.00%
Property management and other services
Business acquisition
Acquired ownership interest in Lillibridge's services and development business (as a percent)		100.00%

Fair Value of the liabilities incurred by the acquirer to former owners of the acquiree, including the fair value of any contingent consideration. If liabilities transferred as consideration remain within the combined entity after the business combination (for example, because the assets or liabilities were transferred to the acquiree rather than to its former owners), and the acquirer therefore retains control of them; in that situation, the acquirer measures those liabilities at their carrying amounts immediately before the acquisition date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 25

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph f(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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