Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest income:
Securities	$ 305,717	$ 354,436	$ 450,708
Mortgage loans	5,509	35
Mortgage loans in securitization trusts	446
Short-term cash investments	1,367	1,283	1,560
Total interest income	313,039	355,754	452,268
Interest expense:
Repurchase agreements	90,744	132,495	197,709
Warehouse lines	597
Collateralized borrowings in securitization trusts	97
Total interest expense	91,438	132,495	197,709
Net interest margin	221,601	223,259	254,559
Other income (loss):
Servicing income	20,111
Management fee income	2,027
Net realized gain on sale of securities	32,731	5,196	(283,012)
Impairment of mortgage-backed securities			(8,102)
Net gain (loss) on mortgage loans	(1,034)	8
Net gain on mortgage servicing rights	10,711
Net gain (loss) on derivative instruments	(188,416)	(141,433)	(69,715)
Net miscellaneous gains and losses	774
Total other income (loss)	(123,096)	(136,229)	(360,829)
Expenses:
Management fee	16,235	16,532	18,180
Share-based compensation	4,256	3,612	2,594
Servicing expenses	3,022
General and administrative	21,899	10,525	7,092
Securitization deal costs	1,473
Total expenses	46,885	30,669	27,866
Net income (loss)	51,620	56,361	(134,136)
Dividends on preferred stock	21,922	21,922	21,922
Net income (loss) available to common shareholders	$ 29,698	$ 34,439	$ (156,058)
Earnings (loss) per share - common stock, basic	$ 0.31	$ 0.36	$ (1.59)
Earnings (loss) per share - common stock, diluted	0.31	0.36	(1.59)
Dividends per share of common stock	$ 1.90	$ 2.00	$ 2.45
Weighted average common shares outstanding, basic	96,665,489	96,603,634	98,337,362
Weighted average common shares outstanding, diluted	96,665,489	96,603,634	98,337,362