Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
ASSETS
Pledged MBS	$ 3,589,872	$ 3,265,979
Common stock, par value	$ 0.01	$ 0.01
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	50,568,790	54,739,111
Common stock, shares outstanding	50,568,790	54,739,111
Series A Preferred Stock [Member]
ASSETS
Preferred Stock, Par Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	8,000,000	8,000,000
Preferred Stock, Shares Issued	2,300,000	2,300,000
Preferred Stock, Shares Outstanding	2,300,000	2,300,000
Preferred Stock, aggregate liquidation preference	$ 57,500	$ 57,500
Series B Preferred Stock [Member]
ASSETS
Preferred Stock, Par Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	7,000,000	7,000,000
Preferred Stock, Shares Issued	2,250,000	2,250,000
Preferred Stock, Shares Outstanding	2,250,000	2,250,000
Preferred Stock, aggregate liquidation preference	$ 56,250	$ 56,250