Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Common Stock Additional Paid-in Capital [Member]	Common Stock Distributions in Excess of Earnings [Member]	Total Stockholders' Equity [Member]	Noncontrolling Interests [Member]
Beginning balance at Dec. 31, 2016	$ 3,759,317	$ 192,411	$ 932	$ 3,457,649	$ (107,997)	$ 3,542,995	$ 216,322
Beginning balance (in shares) at Dec. 31, 2016			93,219,439
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	148,075				136,083	136,083	11,992
Redemption of Series G and H Preferred stock	(200,000)	(192,411)			(7,589)	(200,000)
Issuance of common stock (in shares)			4,427,500
Issuance of common stock	308,812		$ 44	308,768		308,812
Issuance of share-based compensation awards	5,291			5,291		5,291
Non-cash amortization of share-based compensation	19,013			19,013		19,013
Exercise of stock options (in shares)			282,000
Exercise of stock options	12,051		$ 4	12,047		12,051
Settlement of restricted stock units for shares of common stock (in shares)			317,848
Settlement of restricted stock units for shares of common stock	0		$ 3	(3)		0
Repurchase of common stock, stock options and restricted stock units (in shares)			(168,881)
Repurchase of common stock, stock options and restricted stock units	(12,986)		$ (2)	(12,984)		(12,986)
Exchange of common units of the Operating Partnership (in shares)			304,350
Exchange of common units of the Operating Partnership	0		$ 3	10,936		10,939	(10,939)
Contributions from noncontrolling interests in consolidated property partnerships	250					0	250
Distributions to noncontrolling interests in consolidated property partnerships	(12,234)					0	(12,234)
Adjustment for noncontrolling interest	0			(3,171)		(3,171)	3,171
Preferred dividends	(5,774)				(5,774)	(5,774)
Dividends declared per common share and common unit ($1.335 and $1.225 per share/unit for the nine months ended September 2018 and 2017, respectively)	(125,935)				(123,390)	(123,390)	(2,545)
Ending balance at Sep. 30, 2017	3,895,880	$ 0	$ 984	3,797,546	(108,667)	3,689,863	206,017
Ending balance (in shares) at Sep. 30, 2017			98,382,256
Beginning balance at Dec. 31, 2017	$ 3,960,316		$ 986	3,822,492	(122,685)	3,700,793	259,523
Beginning balance (in shares) at Dec. 31, 2017	98,620,333		98,620,333
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 111,036				98,195	98,195	12,841
Issuance of common stock (in shares)			1,817,195
Issuance of common stock	130,744		$ 18	130,726		130,744
Issuance of share-based compensation awards	3,298			3,298		3,298
Non-cash amortization of share-based compensation	24,678			24,678		24,678
Exercise of stock options (in shares)			1,000
Exercise of stock options	41		$ 0	41		41
Settlement of restricted stock units for shares of common stock (in shares)			488,354
Settlement of restricted stock units for shares of common stock	0		$ 4	(4)		0
Repurchase of common stock, stock options and restricted stock units (in shares)			(231,800)
Repurchase of common stock, stock options and restricted stock units	(16,553)		$ (2)	(16,551)		(16,553)
Exchange of common units of the Operating Partnership (in shares)			51,906
Exchange of common units of the Operating Partnership	0		$ 1	1,961		1,962	(1,962)
Contributions from noncontrolling interests in consolidated property partnerships	8,273					0	8,273
Distributions to noncontrolling interests in consolidated property partnerships	(7,006)					0	(7,006)
Adjustment for noncontrolling interest	0			(1,236)		(1,236)	1,236
Dividends declared per common share and common unit ($1.335 and $1.225 per share/unit for the nine months ended September 2018 and 2017, respectively)	(139,908)				(137,164)	(137,164)	(2,744)
Ending balance at Sep. 30, 2018	$ 4,074,919		$ 1,007	$ 3,965,405	$ (161,654)	$ 3,804,758	$ 270,161
Ending balance (in shares) at Sep. 30, 2018	100,746,988		100,746,988