CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income/(loss)	$ 132,511	$ 87,210	$ 284,747	$ (725,207)
Other Comprehensive (Loss):
Unrealized (losses)/gains on securities available-for-sale	(8,029)	15,082	(21,473)	408,585
Reclassification adjustment for securities sales included in net income	0	(60)	0	(389,127)
Reclassification adjustment for impairments included in net income	0	0	0	(344,269)
Derivative hedging instrument fair value changes, net	0	0	0	(50,127)
Changes in fair value of financing agreements at fair value due to changes in instrument-specific credit risk	209	(22,652)	935	(22,652)
Reclassification adjustment for losses related to hedging instruments included in net income	0	7,176	0	72,802
Other Comprehensive (Loss)	(7,820)	(454)	(20,538)	(324,788)
Comprehensive income/(loss) before preferred stock dividends	124,691	86,756	264,209	(1,049,995)
Dividends required on preferred stock	(8,218)	(8,219)	(24,656)	(21,578)
Comprehensive Income/(Loss) Available to Common Stock and Participating Securities	$ 116,473	$ 78,537	$ 239,553	$ (1,071,573)