Condensed Consolidated Statement of Noncontrolling Interests and Equity - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Total	General and Limited Partner, Operating Partnership [Member]	Series A Preferred Operating Partnership [Member]	Series B Preferred Operating Partnership [Member]	Series C Preferred Operating Partnership [Member]	Series D Preferred Operating Partnership [Member]	Series D Preferred Operating Partnership [Member] Preferred Partner [Member] Series D Preferred Stock [Member]	Common Operating Partnership [Member]	Common Operating Partnership [Member] General and Limited Partner, Operating Partnership [Member]	Other [Member]	Par Value [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balances at Dec. 31, 2015	$ 2,372,604		$ 14,189	$ 41,902	$ 10,730	$ 13,710		$ 202,834		$ 162	$ 1,241	$ 2,431,754	$ (6,352)	$ (337,566)
Balances (in shares) at Dec. 31, 2015	124,119,531										124,119,531
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options	$ 313											313
Issuance of common stock upon the exercise of options (in shares)											22,855
Restricted stock grants issued (in shares)											98,373
Restricted stock grants canceled (in shares)											(5,909)
Issuance of common stock, net of offering costs	73,369										$ 9	73,360
Issuance of common stock, net of offering costs (in shares)											831,300
Compensation expense related to stock-based awards	4,093											4,093
Issuance of Operating Partnership units in conjunction with acquisitions		$ 1,405					$ 55,037		$ 1,405
Redemption of Operating Partnership units for sale of property	(7,689)							(7,689)
Redemption of Operating Partnership units for common stock	0							(829)				829
Redemption of Operating Partnership units for common stock (in shares)											23,570
Repurchase of equity portion of 2013 exchangeable senior notes	(870)										$ 2	(872)
Repurchase of equity portion of 2013 exchangeable senior notes (in shares)											148,940
Net income	179,447		3,674	1,257	1,218	465		7,198		(1)				165,636
Other comprehensive income (loss)	(49,945)		(332)					(2,120)					(47,493)
Tax effect from vesting of restricted stock grants and stock option exercises	1,267											1,267
Distributions to Operating Partnership units held by noncontrolling interests	(14,300)		(3,742)	(1,258)	(1,218)	(465)		(7,617)
Dividends paid on common stock at $1.37 per share	(171,514)													(171,514)
Balances at Jun. 30, 2016	$ 2,443,217		$ 13,789	$ 41,901	$ 10,730	$ 68,747		$ 193,182		$ 161	$ 1,252	$ 2,510,744	$ (53,845)	$ (343,444)
Balances (in shares) at Jun. 30, 2016	125,238,660										125,238,660