Condensed Consolidated Statement of Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Series A	Series B	Series C	Operating Partnership	Other	Par Value	Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Balances at Dec. 31, 2013	$ 1,931,895	$ 30,202	$ 33,568	$ 17,177	$ 91,453	$ 1,025	$ 1,157	$ 1,973,159	$ 10,156	$ (226,002)
Balances (in shares) at Dec. 31, 2013	115,755,527						115,755,527
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon the exercise of options	1,056						1	1,055
Issuance of common stock upon the exercise of options (in shares)							69,265
Restricted stock grants issued (in shares)							47,000
Restricted stock grants cancelled (in shares)							(1,883)
Compensation expense related to stock-based awards	1,121							1,121
Net income	41,209	1,751	504	237	1,377					37,340
Other comprehensive income	(2,747)	(22)			(97)				(2,628)
Tax effect from vesting of restricted stock grants and stock option exercises	1,262							1,262
Distributions to Operating Partnership units held by noncontrolling interests	(4,265)	(1,833)	(504)	(237)	(1,691)
Dividends paid on common stock at $0.40 per share	(46,347)									(46,347)
Balances at Mar. 31, 2014	$ 1,923,184	$ 30,098	$ 33,568	$ 17,177	$ 91,042	$ 1,025	$ 1,158	$ 1,976,597	$ 7,528	$ (235,009)
Balances (in shares) at Mar. 31, 2014	115,869,909						115,869,909