Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 71,327	$ (406,659)
Other comprehensive income (loss):
Reclassification adjustment for realized gain on sale of available for sale Agency Securities	(7,354)	(93,325)
Reclassification adjustment for credit loss expense on available for sale Agency Securities	0	1,012
Net unrealized loss on available for sale Agency Securities	(34,880)	(38,143)
Other comprehensive loss	(42,234)	(130,456)
Comprehensive Income (Loss)	$ 29,093	$ (537,115)