Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Pledged securities	$ 550,856	$ 690,592
Distressed residential mortgage loans, net, held in securitization trusts	$ 152,621	$ 195,347
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	200,000,000	200,000,000
Preferred stock, shares issued (in shares)	6,600,000	6,600,000
Preferred stock, shares outstanding (in shares)	6,600,000	6,600,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	111,891,130	111,474,521
Common stock, shares outstanding (in shares)	111,891,130	111,474,521
Series B Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, cumulative redeemable dividend rate	7.75%	7.75%
Preferred stock, liquidation preference per share (in dollars per share)	$ 25	$ 25
Preferred stock, shares authorized (in shares)	6,000,000	6,000,000
Preferred stock, shares issued (in shares)	3,000,000	3,000,000
Preferred stock, shares outstanding (in shares)	3,000,000	3,000,000
Series C Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, cumulative redeemable dividend rate	7.875%	7.875%
Preferred stock, liquidation preference per share (in dollars per share)	$ 25	$ 25
Preferred stock, shares authorized (in shares)	4,140,000	4,140,000
Preferred stock, shares issued (in shares)	3,600,000	3,600,000
Preferred stock, shares outstanding (in shares)	3,600,000	3,600,000
Available-for-sale securities
Investment securities held in securitization trusts	$ 45,400	$ 43,897