Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Preferred Stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred Stock, shares authorized	50,000,000	50,000,000
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized	450,000,000	450,000,000
Common stock, shares issued	113,619,471	123,110,454
Common stock, shares outstanding	113,619,471	123,110,454
Series A Cumulative Redeemable Preferred Stock
Preferred Stock, dividend rate stated percentage	7.75%	7.75%
Preferred Stock, shares issued	5,600,000	5,600,000
Preferred Stock, shares outstanding	5,600,000	5,600,000
Preferred Stock, aggregate liquidation preference	$ 140,000	$ 140,000
Series B Cumulative Redeemable Preferred Stock
Preferred Stock, dividend rate stated percentage	7.75%	7.75%
Preferred Stock, shares issued	6,200,000	6,200,000
Preferred Stock, shares outstanding	6,200,000	6,200,000
Preferred Stock, aggregate liquidation preference	$ 155,000	$ 155,000