Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Pledged MBS	$ 2,714,312	$ 3,150,610
Shareholders' Equity:
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	5,665,101	4,571,937
Preferred stock, shares outstanding	5,665,101	4,571,937
Preferred stock, aggregate liquidation preference	$ 141,628	$ 114,298
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	51,262,350	49,153,463
Common stock, shares outstanding	51,262,350	49,153,463