Real Estate (Details 2) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Properties acquired			1
Property Units Acquired			322
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 108,000,000		$ 108,000,000
Disposed Properties			92
Disposed Units			28,328
Proceeds From Sale Of Property			4,497,423,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	401,703,000	103,394,000	1,990,577,000	307,447,000
Net gain (loss) on sales of land parcels	(2,437,000)	0	12,179,000	0
Consolidated Rental Properties [Member]
Properties acquired			1
Property Units Acquired			322
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	91,500,000		91,500,000
Disposed Properties			92
Disposed Units			28,328
Proceeds From Sale Of Property			4,362,689,000
Land [Member]
Property Units Acquired			0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	16,500,000		16,500,000
Proceeds From Sale Of Property			77,650,000
Land parcels acquired			1
Disposed Land Parcels			6
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