Real Estate Real Estate (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Properties acquired		1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 108,000,000	$ 1,047,545,000
Disposed Properties	94	35
Disposed Units	29,180	9,012
Proceeds From Sale Of Property	4,616,073,000	1,061,334,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	2,036,505,000	548,278,000	826,489,000
Net gain on sales of land parcels	12,227,000	0	4,217,000
Consolidated Rental Properties [Member]
Properties acquired	1	9
Property Units Acquired	322	1,896
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	91,500,000	906,305,000
Disposed Properties	94	35
Disposed Units	29,180	9,012
Proceeds From Sale Of Property	4,459,339,000	1,061,334,000
Land [Member]
Property Units Acquired	0	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	16,500,000	141,240,000
Proceeds From Sale Of Property	99,650,000
Land parcels acquired	1	6
Disposed Land Parcels	7
Unconsolidated Land Parcel Disposition	1
Commercial Real Estate [Member]
Proceeds From Sale Of Property	30,734,000
Commercial Properties Disposed	1
Unconsolidated Institutional Joint Ventures [Member]
Proceeds From Sale Of Property	$ 26,350,000