Real Estate Real Estate (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity Method Investment, Ownership Percentage	20.00%
Properties acquired			1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 498,640,000	$ 108,000,000
Adjusted purchase price of partner's interest in joint venture	64,200,000
Payments to Acquire Interest in Subsidiaries and Affiliates	44,800,000
Revaluation Loss	3,500,000
Disposed Properties	11	94
Disposed Units	3,480	29,180
Proceeds From Sale Of Property	592,070,000	4,616,073,000
Net gain on sales of real estate properties	212,685,000	0	0
Net gain on sales of land parcels	5,277,000	12,227,000	0
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		2,000,000,000
Consolidated Rental Properties [Member]
Properties acquired	6	1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	469,850,000	91,500,000
Disposed Properties	10	94
Disposed Units	3,092	29,180
Proceeds From Sale Of Property	466,968,000	4,459,339,000
Land [Member]
Land parcels acquired	2	1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	28,790,000	16,500,000
Disposed Land Parcels	3	7
Proceeds From Sale Of Property	62,602,000	99,650,000
Unconsolidated Land Parcel Disposition	0	1
Commercial Real Estate [Member]
Proceeds From Sale Of Property		30,734,000
Commercial Properties Disposed	0	1
Unconsolidated Properties [Member]
Disposed Properties	1
Disposed Units	388
Proceeds From Sale Of Property	62,500,000	26,350,000
anticipated stabilized real estate value at completion [Member]
Real Estate Investments, Other	87,500,000
Unconsolidated Properties [Member]
Disposed Properties	1
San Norterra [Domain]
Equity Method Investment, Ownership Percentage	85.00%
Unconsolidated Properties [Member]
Net gain on sales of real estate properties	4,899,000
Series P [Domain]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage	95.00%
Liquidation Value Preferred Interests	$ 18,400,000