Reportable Segments - Reconciliation of NOI from Rental Real Estate Specific to Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Rental income	$ 669,374	$ 639,620	$ 1,331,676	$ 1,272,451
Property and maintenance expense	(108,461)	(103,744)	(223,531)	(211,946)
Real estate taxes and insurance expense	(91,446)	(89,482)	(182,888)	(181,396)
Operating income	369,260	217,603	579,229	556,685
Same Store, Non-same Store and Other
Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items]
Rental income	669,374	639,620	1,331,676	1,272,451
Property and maintenance expense	(108,461)	(103,744)	(223,531)	(211,946)
Real estate taxes and insurance expense	(91,446)	(89,482)	(182,888)	(181,396)
Total operating expenses	(199,907)	(193,226)	(406,419)	(393,342)
Operating income	$ 469,467	$ 446,394	$ 925,257	$ 879,109