CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Restricted cash	$ 48,301,244	$ 218,100,529
Loans and investments, net	1,450,334,341	1,459,475,650
Real estate owned, net	60,845,509	84,925,641
Due from related party	8,082,265	36,515
Other assets	29,558,430	31,787,451
Collateralized loan obligations	758,899,661	453,101,661
Collateralized debt obligations		331,219,478
Other liabilities	$ 51,054,321	$ 49,332,212
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	50,962,516	50,477,308
Common stock, shares outstanding (in shares)	50,962,516	50,477,308
8.25% Series A preferred stock
Preferred stock, dividend rate (as a percent)	8.25%	8.25%
Preferred stock, aggregate liquidation preference	$ 38,787,500	$ 38,787,500
Preferred stock, shares issued (in shares)	1,551,500	1,551,500
Preferred stock, shares outstanding (in shares)	1,551,500	1,551,500
7.75% Series B preferred stock
Preferred stock, dividend rate (as a percent)	7.75%	7.75%
Preferred stock, aggregate liquidation preference	$ 31,500,000	$ 31,500,000
Preferred stock, shares issued (in shares)	1,260,000	1,260,000
Preferred stock, shares outstanding (in shares)	1,260,000	1,260,000
8.50% Series C preferred stock
Preferred stock, dividend rate (as a percent)	8.50%	8.50%
Preferred stock, aggregate liquidation preference	$ 22,500,000	$ 22,500,000
Preferred stock, shares issued (in shares)	900,000	900,000
Preferred stock, shares outstanding (in shares)	900,000	900,000
Consolidated VIEs
Restricted cash	$ 46,695,819	$ 216,405,894
Loans and investments, net	968,970,064	968,600,472
Real estate owned, net	0	80,732,144
Due from related party	36,451	0
Other assets	6,969,201	9,625,969
Collateralized loan obligations	758,899,661	453,101,661
Collateralized debt obligations	0	331,219,478
Other liabilities	$ 1,224,193	$ 7,385,474