CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income/(loss)	$ 66,714	$ 96,578	$ 152,236	$ (812,417)
Other Comprehensive (Loss):
Unrealized (losses)/gains on securities available-for-sale	(9,589)	48,715	(13,444)	393,503
Reclassification adjustment for securities sales included in net income	0	(144,736)	0	(389,067)
Reclassification adjustment for impairments included in net income	0	0	0	(344,269)
Derivative hedging instrument fair value changes, net	0	0	0	(50,126)
Changes in fair value of financing agreements at fair value due to changes in instrument-specific credit risk	491	0	726	0
Reclassification adjustment for losses related to hedging instruments included in net income	0	64,032	0	65,625
Other Comprehensive (Loss)	(9,098)	(31,989)	(12,718)	(324,334)
Comprehensive income/(loss) before preferred stock dividends	57,616	64,589	139,518	(1,136,751)
Dividends required on preferred stock	(8,219)	(8,144)	(16,438)	(13,359)
Comprehensive Income/(Loss) Available to Common Stock and Participating Securities	$ 49,397	$ 56,445	$ 123,080	$ (1,150,110)