Real Estate (Details 2) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Properties acquired			1
Property Units Acquired			322
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 108,000,000		$ 108,000,000
Disposed Properties			82
Disposed Units			24,197
Proceeds From Sale Of Property			3,795,566,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	389,952,000	71,097,000	1,588,874,000	204,053,000
Net gain on sales of land parcels	14,616,000	0	14,616,000	0
Consolidated Rental Properties [Member]
Properties acquired			1
Property Units Acquired			322
Business Acquisition, Cost of Acquired Entity, Purchase Price	91,500,000		91,500,000
Disposed Properties			82
Disposed Units			24,197
Proceeds From Sale Of Property			3,705,082,000
Land [Member]
Property Units Acquired			0
Business Acquisition, Cost of Acquired Entity, Purchase Price	16,500,000		16,500,000
Proceeds From Sale Of Property			59,750,000
Land parcels acquired			1
Disposed Land Parcels			5
Commercial Real Estate [Member]
Proceeds From Sale Of Property			$ 30,734,000
Commercial Properties Disposed			1