Real Estate (Details 2) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) property	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Acquired Properties | property			1
Apartment Units			202
Purchase Price	$ 158,075		$ 158,075
Disposed Properties | property			7
Apartment Units			1,707
Sales Price			$ 464,812
Net gain on sales of real estate properties	66,939	$ 113,641	295,692	$ 128,544
Real Estate Investment Property, Net	22,244,786		22,244,786		$ 22,242,578
Noncontrolling Interests – Partially Owned Properties/Partners' equity	4,643		4,643		124,909
Deposits – restricted	135,674		135,674		$ 72,303
Joint Venture Partner [Member]
Purchase Price	75,700		75,700
Land purchase price	57,900		57,900
Real Estate Investment Property, Net	116,700		116,700
Noncontrolling Interests – Partially Owned Properties/Partners' equity	117,300		117,300
Accrued Liabilities	(1,100)		(1,100)
Deposits – restricted	1,700		1,700
Company's Portion [Member]
Purchase Price	102,500		102,500
Land purchase price	76,100		$ 76,100
Rental Properties
Acquired Properties | property			1
Apartment Units			202
Purchase Price	130,275		$ 130,275
Disposed Properties | property			7
Apartment Units			1,707
Sales Price			$ 464,812
Land [Member]
Land Parcels Acquired | property			3
Purchase Price	$ 27,800		$ 27,800
Commercial Real Estate [Member]
Sales Price			$ 123,300