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 Real Estate Funds [Member]	Noncontrolling Interest [Member] Consolidated Joint Ventures [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)	$ 414,637	$ 236,849	$ 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)	63,602	236,849	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 (loss) income	(7,487)			(6,494)		(674)	1,252	(1,571)
Common shares issued upon redemption of common units		$ 8	14,419
Redemption of minority interest in operating partnerships								(14,427)
Common shares issued upon redemption of common units		830,000
Common shares issued under Omnibus share plan, net of shares withheld for taxes		95,000
Dividends and distributions	(25,147)			(20,239)				(4,908)
Change in value of interest rate swaps	(29,867)				(24,058)			(5,809)
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	107				86			21
Amortization of equity awards	3,845		747					3,098
Other	345		320	18		7
Ending balance at Mar. 31, 2016	4,901,311	$ 2,130	3,818,344	(62,835)	(31,815)	62,935	238,101	874,451
Common stock, shares outstanding at Mar. 31, 2016		213,037,000
Beginning balance at Dec. 31, 2016	$ 4,885,947	$ 2,300	4,116,987	(129,654)	372	64,793	253,788	577,361
Common Stock Shares Outstanding at Dec. 31, 2016	230,015,356	230,015,000
Net (loss) income	$ 1,629			372		(88)	1,291	54
Common shares issued upon redemption of common units		$ 13	21,803
Redemption of minority interest in operating partnerships								(21,816)
Common shares issued upon redemption of common units		1,304,000
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		61,000
Dividends and distributions	(25,207)			(21,981)				(3,226)
Contributions from noncontrolling interests in joint ventures and funds	7,472					2,500	4,972
Distributions to noncontrolling interests	(32,012)						(32,012)
Change in value of interest rate swaps	4,032				3,518			514
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	(222)				(194)			(28)
Amortization of equity awards	3,873		633					3,240
Ending balance at Mar. 31, 2017	$ 4,845,358	$ 2,313	$ 4,139,423	$ (151,417)	$ 3,696	$ 67,205	$ 228,039	$ 556,099
Common stock, shares outstanding at Mar. 31, 2017	231,379,820	231,380,000