CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Restatement Adjustment	Common Stock [Member]	Common Stock [Member] Restatement Adjustment	Additional Paid in Capital [Member]	Additional Paid in Capital [Member] Restatement Adjustment	Earnings Less than Distributions [Member]	Earnings Less than Distributions [Member] Restatement Adjustment	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Restatement Adjustment	Noncontrolling Interest Consolidated Joint Ventures [Member]	Noncontrolling Interest Consolidated Joint Ventures [Member] Restatement Adjustment	Noncontrolling Interest Consolidated Real Estate Fund [Member]	Noncontrolling Interest Consolidated Real Estate Fund [Member] Restatement Adjustment	Noncontrolling Interest Operating Partnership [Member]	Noncontrolling Interest Operating Partnership [Member] Restatement Adjustment
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			230,015,000
Net income (loss)	114,408						93,174				(11,029)		20,195		12,068
Common shares issued upon redemption of common units			$ 100		166,424
Common shares issued upon redemption of common units			10,001,000
Redemption of minority interest in operating partnerships															(166,524)
Common shares 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			58,000
Dividends and distributions	(75,629)						(67,425)								(8,204)
Contributions from noncontrolling interests	100,777										96,472		4,305
Distributions to noncontrolling interests	(115,549)										(41,203)		(74,346)
Consolidation of 50 Beale Street	110,007										110,007
Change in value of interest rate swaps	729								600						129
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	39								42						(3)
Amortization of equity awards	13,126				2,244										10,882
Other	8,455				610										7,845
Ending balance at Sep. 30, 2017	5,042,156		$ 2,400		4,286,265		(104,059)		1,014		408,035		14,947		433,554
Common stock, shares outstanding at Sep. 30, 2017			240,074,000
Beginning balance at Dec. 31, 2017	5,022,084	$ 5,029,170	$ 2,403	$ 2,403	4,297,948	$ 4,297,948	(133,693)	$ (133,164)	10,083	$ 10,083	404,997	$ 404,997	14,549	$ 21,106	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	240,427,022		240,427,000	240,427,000
Net income (loss)	$ 10,398						3,829				5,520		668		381
Common shares issued upon redemption of common units			$ 2		3,459
Common shares issued upon redemption of common units			203,000
Redemption of minority interest in operating partnerships															(3,461)
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			68,000
Repurchases of common shares	(3,569)		$ (3)		(3,566)
Repurchases of common shares			(237,000)
Dividends and distributions	(79,843)						(72,149)								(7,694)
Contributions from noncontrolling interests	44,381												44,381
Distributions to noncontrolling interests	(10,583)										(10,583)
Change in value of interest rate swaps	23,738								21,492						2,246
Pro rata share of other comprehensive income (loss) of unconsolidated joint ventures	(105)								(44)				(56)		(5)
Amortization of equity awards	16,209				2,206										14,003
Other	(171)				1,282		(171)		(1)						(1,281)
Ending balance at Sep. 30, 2018	$ 5,029,412		$ 2,402		$ 4,301,329		$ (201,868)		$ 31,530		$ 399,934		$ 66,099		$ 429,986
Common stock, shares outstanding at Sep. 30, 2018	240,461,106		240,461,000