Real Estate Real Estate Dispositions (Details) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Disposed Properties	63
Disposed Units	18,452
Proceeds From Sale Of Property	$ 2,975,187,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	1,198,922,000	132,956,000
Consolidated Rental Properties [Member]
Disposed Properties	63
Disposed Units	18,452
Proceeds From Sale Of Property	$ 2,975,187,000

Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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