Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest income	$ 91,898	$ 100,244	$ 105,644
Interest expense	25,231	22,605	25,915
Net interest income	66,667	77,639	79,729
Loss on derivative instruments, net	(5,606)	(43,128)	(53,393)
(Loss) gain on sale of investments, net	(4,238)	(978)	16,223
Fair value adjustments, net	103	69	208
Other income, net	880	610	1,046
General and administrative expenses:
Compensation and benefits	(7,550)	(9,103)	(9,509)
Other general and administrative	(7,157)	(8,565)	(6,498)
Net income	43,099	16,544	27,806
Preferred stock dividends	(9,185)	(9,176)	(9,176)
Net income to common shareholders	33,914	7,368	18,630
Other comprehensive income:
Change in net unrealized gain on available-for-sale investments	(23,828)	(38,561)	64,567
Reclassification adjustment for loss (gain) on sale of investments, net	4,238	978	(16,223)
Reclassification adjustment for de-designated cash flow hedges	(251)	3,499	6,788
Total other comprehensive (loss) income	(19,841)	(34,084)	55,132
Comprehensive income (loss) to common shareholders	$ 14,073	$ (26,716)	$ 73,762
Net income per common share-basic and diluted	$ 0.69	$ 0.14	$ 0.34
Weighted average common shares-basic and diluted	49,114	52,847	54,701