Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
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	$ 385,636	$ 192,407	$ 254,543	$ 141,590	$ 237,486	$ 238,199	$ 165,194	$ 235,781	$ 974,175	$ 876,660	$ 1,033,708
Indirect operating expenses, net of corporate income									76,522	65,398	61,403
Investment Income, Investment Expense									7,709	5,936	4,822
Expensed transaction, development and other pursuit costs, net of recoveries									4,309	2,736	9,922
Interest expense, net									220,974	199,661	187,510
Loss on extinguishment of debt, net									17,492	25,472	7,075
General and administrative expense									56,365	50,673	45,771
Equity in income of unconsolidated real estate entities									(15,270)	(70,744)	(64,962)
Depreciation expense									631,196	584,150	531,434
Income tax (benefit) expense									(160)	141	305
Casualty and impairment loss (gain), net									215	6,250	(3,935)
Gain on sale of communities									(374,976)	(252,599)	(374,623)
(Loss) gain on other real estate transactions									(345)	10,907	(10,224)
Net operating income from real estate assets sold or held for sale									(58,620)	(84,650)	(114,219)
Net operating income									$ 1,539,586	$ 1,419,991	$ 1,313,987