Segment Reporting (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting [Abstract]
Percentage of physical occupancy	90.00%
Anniversary of Completion of Development or Redevelopment (in years)	1 year
Reconciliation of NOI to net income
Net income	$ 827,706	$ 786,103	$ 974,175
Indirect operating expenses, net of corporate income	97,443	83,008	80,227
Other Nonoperating Expense	12,399	4,991	3,265
Interest expense, net	214,151	203,585	220,974
Loss on extinguishment of debt, net	9,333	602	17,492
General and administrative expense	60,343	58,042	60,369
Equity in income of unconsolidated real estate entities	(6,422)	(8,652)	(15,270)
Depreciation expense	707,331	661,578	631,196
Income Tax Expense (Benefit)	(3,247)	13,003	(160)
Casualty and impairment loss, net	0	0	215
Gain on sale of communities	(340,444)	(166,105)	(374,976)
(Loss) gain on other real estate transactions	(440)	(439)	(345)
Gain (Loss) on Sale of Other Investments, Net of Marketing and Administrative Costs	(2,551)	3,812	1,044
Other Selling, General and Administrative Expense	5,662	3,812	1,044
Net operating income from real estate assets sold or held for sale	(28,412)	(45,354)	(113,074)
Net operating income	$ 1,547,190	$ 1,594,174	$ 1,485,132