CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid in Capital [Member]	Earnings Less than Distributions [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member] Consolidated Joint Ventures [Member]	Noncontrolling Interest [Member] Consolidated Real Estate Funds [Member]	Noncontrolling Interest [Member] Operating Partnership [Member]
Beginning balance (Scenario, Previously Reported) at Dec. 31, 2015	$ 5,310,550	$ 2,122	$ 3,802,858	$ (36,120)	$ (7,843)	$ 236,849	$ 414,637	$ 898,047
Beginning balance (Scenario, Adjustment, Deconsolidation of real estate fund investments upon adoption of ASU 2015-02) at Dec. 31, 2015	(351,035)						(351,035)
Beginning balance at Dec. 31, 2015	4,959,515	$ 2,122	3,802,858	(36,120)	(7,843)	236,849	63,602	898,047
Common Stock Shares Outstanding (Scenario, Previously Reported) at Dec. 31, 2015		212,112,000
Common Stock Shares Outstanding at Dec. 31, 2015		212,112,000
Net income (loss)	423			(3,306)		5,359	(752)	(878)
Common shares issued upon redemption of common units		$ 73	124,006
Redemption of minority interest in operating partnerships								(124,079)
Common shares issued upon redemption of common units		7,277,000
Common shares issued under Omnibus share plan, net of shares withheld for taxes		101,000
Dividends and distributions	(50,298)			(41,090)				(9,208)
Distributions to noncontrolling interests	(1,740)					(1,740)
Change in value of interest rate swaps	(41,614)				(33,705)			(7,909)
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	63				50			13
Amortization of equity awards	6,719		1,175					5,544
Other	(125)		(167)	20		15	7
Ending balance at Jun. 30, 2016	4,872,943	$ 2,195	3,927,872	(80,496)	(41,498)	240,483	62,857	761,530
Common stock, shares outstanding at Jun. 30, 2016		219,490,000
Beginning balance at Dec. 31, 2016	$ 4,885,947	$ 2,300	4,116,987	(129,654)	372	253,788	64,793	577,361
Common Stock Shares Outstanding at Dec. 31, 2016	230,015,356	230,015,000
Net income (loss)	$ 139,811			103,388		3,188	20,081	13,154
Common shares issued upon redemption of common units		$ 82	135,877
Redemption of minority interest in operating partnerships								(135,959)
Common shares issued upon redemption of common units		8,207,000
Common units issued under Omnibus share plan, net of shares withheld for taxes	(154)			(154)
Common shares issued under Omnibus share plan, net of shares withheld for taxes		62,000
Dividends and distributions	(50,418)			(44,617)				(5,801)
Contributions from noncontrolling interests	9,278					4,973	4,305
Distributions to noncontrolling interests	(107,162)					(32,816)	(74,346)
Change in value of interest rate swaps	(9)				(67)			58
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	(187)				(162)			(25)
Amortization of equity awards	8,805		1,522					7,283
Ending balance at Jun. 30, 2017	$ 4,885,911	$ 2,382	$ 4,254,386	$ (71,037)	$ 143	$ 229,133	$ 14,833	$ 456,071
Common stock, shares outstanding at Jun. 30, 2017	238,283,591	238,284,000