CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in-Capital [Member]	Earnings (Less than) In Excess of 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, 2014	$ 5,554,953	$ 2,122	$ 3,851,432	$ 57,308		$ 347,818	$ 338,070	$ 958,203
Common stock, shares outstanding (Scenario, Previously Reported) at Dec. 31, 2014		212,107,000
Net income (loss) | Scenario, Previously Reported	21,143			(4,419)		5,459	21,173	(1,070)
Net income (loss)	21,143
Common units issued under Omnibus share plan | Scenario, Previously Reported	4		(2,127)					2,131
Common shares issued under Omnibus share plan | Scenario, Previously Reported		5,000
Dividends and distributions | Scenario, Previously Reported	(110,525)			(88,874)				(21,651)
Contributions from noncontrolling interests | Scenario, Previously Reported	167,929					2,530	165,399
Distributions to noncontrolling interests | Scenario, Previously Reported	(56,636)					(731)	(55,905)
Change in value of interest rate swaps | Scenario, Previously Reported	(9,241)				$ (7,431)			(1,810)
Change in value of interest rate swaps	(9,241)
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures | Scenario, Previously Reported	(512)				(412)			(100)
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	(512)
Acquisition of noncontrolling interests' in consolidated joint ventures and funds | Scenario, Previously Reported	(263,416)		(91,417)			(118,227)	(53,772)
Adjustments to noncontrolling interests | Scenario, Previously Reported			43,981					(43,981)
Amortization of equity awards | Scenario, Previously Reported	7,784		1,459					6,325
Other | Scenario, Previously Reported	(933)		(470)	(135)			(328)
Ending 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
Ending balance (Scenario, Adjustment, Deconsolidation of real estate fund investments upon adoption of ASU 2015-02) at Dec. 31, 2015	(351,035)						(351,035)
Ending 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)	2,069			(9,934)		15,423	(1,316)	(2,104)
Common shares issued upon redemption of common units		$ 178	312,079
Common shares issued upon redemption of common units		17,808,000
Redemption of minority interest in operating partnerships								(312,257)
Common shares issued under Omnibus share plan		95,000
Dividends and distributions	(100,601)			(83,805)				(16,796)
Contributions from noncontrolling interests	7,651					5,151	2,500
Distributions to noncontrolling interests	(3,636)					(3,636)
Change in value of interest rate swaps	8,161				8,203			(42)
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	17				12			5
Amortization of equity awards	12,528		2,034					10,494
Other	243		16	205		1	7	14
Ending 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)	$ 107,176			86,381		(10,365)	19,797	11,363
Common shares issued upon redemption of common units		$ 103	172,625
Common shares issued upon redemption of common units		10,359,000
Redemption of minority interest in operating partnerships								(172,728)
Common units issued under Omnibus share plan	(154)			(154)
Common shares issued under Omnibus share plan		53,000
Dividends and distributions	(100,840)			(90,266)				(10,574)
Contributions from noncontrolling interests	100,777					96,472	4,305
Distributions to noncontrolling interests	(119,251)					(44,905)	(74,346)
Consolidation of 50 Beale	110,007					110,007
Change in value of interest rate swaps	10,618				9,559			1,059
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	160				152			8
Amortization of equity awards	18,790		3,085					15,705
Other	8,854		5,251					3,603
Ending balance at Dec. 31, 2017	$ 5,022,084	$ 2,403	$ 4,297,948	$ (133,693)	$ 10,083	$ 404,997	$ 14,549	$ 425,797
Common stock, shares outstanding at Dec. 31, 2017	240,427,022	240,427,000