CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Previously Reported [Member]	Restatement Adjustment [Member]	Common Stock [Member]	Common Stock [Member] Previously Reported [Member]	Additional Paid in Capital [Member]	Additional Paid in Capital [Member] Previously Reported [Member]	Earnings Less than Distributions [Member]	Earnings Less than Distributions [Member] Previously Reported [Member]	Earnings Less than Distributions [Member] Restatement Adjustment [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Other Comprehensive Income [Member] Previously Reported [Member]	Noncontrolling Interest Consolidated Joint Ventures [Member]	Noncontrolling Interest Consolidated Joint Ventures [Member] Previously Reported [Member]	Noncontrolling Interest Consolidated Real Estate Fund [Member]	Noncontrolling Interest Consolidated Real Estate Fund [Member] Previously Reported [Member]	Noncontrolling Interest Consolidated Real Estate Fund [Member] Restatement Adjustment [Member]	Noncontrolling Interest Operating Partnership [Member]	Noncontrolling Interest Operating Partnership [Member] Previously Reported [Member]
Beginning balance at Dec. 31, 2017	$ 5,029,170	$ 5,022,084		$ 2,403	$ 2,403	$ 4,297,948	$ 4,297,948	$ (133,164)	$ (133,693)		$ 10,083	$ 10,083	$ 404,997	$ 404,997	$ 21,106	$ 14,549		$ 425,797	$ 425,797
Beginning balance (Basis adjustment upon adoption of ASU 2017-05) at Dec. 31, 2017			$ 7,086							$ 529							$ 6,557
Common stock, shares outstanding at Dec. 31, 2017				240,427,000	240,427,000
Net income	2,715							1,114					1,055		430			116
Common shares issued upon redemption of common units						123
Common shares issued upon redemption of common units				7,000
Redemption of minority interest in operating partnerships																		(123)
Common shares issued under Omnibus share plan, net of shares withheld for taxes	(213)							(213)
Common shares issued under Omnibus share plan, net of shares withheld for taxes				72,000
Dividends and distributions	(26,627)							(24,051)										(2,576)
Contributions from noncontrolling interests	29,920														29,920
Distributions to noncontrolling interests	(1,915)												(1,915)
Change in value of interest rate swaps	14,551										13,179							1,372
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	54										50							4
Amortization of equity awards	6,584					838												5,746
Other	(169)					(5,700)		(171)										5,702
Ending balance at Mar. 31, 2018	5,054,070			$ 2,403		4,293,209		(156,485)			23,312		404,137		51,456			436,038
Common stock, shares outstanding at Mar. 31, 2018				240,506,000
Beginning balance at Dec. 31, 2018	$ 4,891,664			$ 2,329		4,201,756		(219,906)			16,621		394,995		66,887			428,982
Common stock, shares outstanding at Dec. 31, 2018	233,135,704			233,136,000
Net income	$ 7,000							3,709					2,794		94			403
Common shares issued upon redemption of common units				$ 13		21,969
Common shares issued upon redemption of common units				1,288,000
Redemption of minority interest in operating partnerships																		(21,982)
Common shares issued under Omnibus share plan, net of shares withheld for taxes	(301)			$ 3				(304)
Common shares issued under Omnibus share plan, net of shares withheld for taxes				54,000
Dividends and distributions	(25,949)							(23,448)										(2,501)
Contributions from noncontrolling interests	14,496														14,496
Distributions to noncontrolling interests	(30,777)												(30,777)
Change in value of interest rate swaps	(9,026)										(8,142)							(884)
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	(108)										(58)				(43)			(7)
Amortization of equity awards	7,637					697												6,940
Other						(6,362)												6,362
Ending balance at Mar. 31, 2019	$ 4,854,636			$ 2,345		$ 4,218,060		$ (239,949)			$ 8,421		$ 367,012		$ 81,434			$ 417,313
Common stock, shares outstanding at Mar. 31, 2019	234,478,379			234,478,000