Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Percentage of physical occupancy									95.00%
Anniversary of Completion of Development or Redevelopment (in years)									1 year
Reconciliation of NOI to net income
Net income	$ 237,486	$ 238,199	$ 165,194	$ 235,781	$ 242,183	$ 356,329	$ 197,319	$ 237,877	$ 876,660	$ 1,033,708	$ 741,733
Indirect operating expenses, net of corporate income									65,398	61,403	56,973
Investments and investment management expense									5,936	4,822	4,370
Expensed acquisition, development and other pursuit costs, net of recoveries									2,736	9,922	6,822
Interest expense, net									199,661	187,510	175,615
Loss (gain) on extinguishment of debt, net									25,472	7,075	(26,736)
General and administrative expense									50,673	45,771	42,774
Equity in income of unconsolidated real estate entities									(70,744)	(64,962)	(70,018)
Depreciation expense									584,150	531,434	477,923
Income tax expense									141	305	1,483
Casualty and impairment loss (gain), net									6,250	(3,935)	(10,542)
Gain on sale of communities									(252,599)	(374,623)	(115,625)
(Loss) gain on other real estate transactions									10,907	(10,224)	(9,647)
Net operating income from real estate assets sold or held for sale									(14,573)	(44,263)	(59,383)
Net operating income									$ 1,490,068	$ 1,383,943	$ 1,215,742