Fair Value of Financial Instruments (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010
Fair Value of Financial Instruments
Fixed rate debt	$ 4,500,000,000
Floating rate debt	1,100,000,000
Estimated fair value of debt and preferred equity investments, low end of range	495,100,000
Estimated fair value of debt and preferred equity investments, high end of range	553,300,000
Debt and preferred equity investments	582,418,000	963,772,000
Level 3
Fair Value of Financial Instruments
Fixed rate debt	4,800,000,000
Floating rate debt	$ 1,100,000,000

Represents the high end of the range of estimated fair value for investments in mortgage loans on real estate.

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- Definition

Represents the low end of the range of estimated fair value for investments in mortgage loans on real estate.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

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- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

+ Details

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- Definition

The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ Details

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- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 60
-Paragraph 47
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 7
-Section 03
-Paragraph 1
-Subparagraph c

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(c))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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