Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest income	$ 96,468	$ 170,168	$ 110,051
Interest expense	(32,615)	(114,111)	(59,574)
Net interest income	63,853	56,057	50,477
Gain (loss) on sale of investments, net	308,084	(5,755)	(23,373)
Loss on derivative instruments, net	172,290	186,949	3,461
Gain (loss) on investments, net	20	(56)	52
Other operating (expense) income, net	(1,057)	22	(1,567)
General and administrative expenses:
Compensation and benefits	(11,743)	(7,520)	(6,605)
Other general and administrative	(9,337)	(8,467)	(8,500)
Net income (loss)	177,530	(152,668)	7,023
Preferred stock dividends	(13,599)	(12,967)	(11,801)
Preferred stock redemption charge	3,914	0	0
Net income (loss) to common shareholders	160,017	(165,635)	(4,778)
Other comprehensive income:
Unrealized gain (loss) on available-for-sale investments, net	214,539	203,995	(50,218)
Reclassification adjustment for (gain) loss on sale of available-for-sale investments, net	(308,084)	5,755	23,373
Reclassification adjustment for de-designated cash flow hedges	0	(165)	(237)
Total other comprehensive (loss) income	(93,545)	209,585	(27,082)
Comprehensive income (loss) to common shareholders	$ 66,472	$ 43,950	$ (31,860)
Net income (loss) per common share-basic and diluted	$ 6.93	$ (7.01)	$ (0.25)
Weighted average common shares-basic and diluted	23,106	23,620	19,235