Income Taxes - Reconciliation of GAAP Net Income to Estimated REIT Taxable Income (Details) - USD ($) $ in Thousands			12 Months Ended
	Feb. 27, 2020	Jul. 29, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investments, Owned, Federal Income Tax Note [Line Items]
GAAP net income (loss)			$ 15,363	$ (215,112)	$ (249,905)
Book to tax differences:
TRS (income) loss			37	(51)	(147)
Premium amortization expense			(148)	(261)	0
Agency Securities, trading			77,145	(19,557)	0
Credit Risk and Non-Agency Securities			0	188,075	24,459
Interest-Only Securities			0	0	85
U.S. Treasury Securities			9,391	(21,357)	(2,024)
Changes in interest rate contracts			(77,300)	268,159	375,493
(Gain) Loss on Security sales			(10,952)	(143,877)	(9,611)
Credit loss expense			0	1,012	0
Amortization of deferred hedging costs			(163,837)	(152,092)	(69,302)
Other			1,830	1,544	18
Estimated REIT taxable income (loss)			(148,471)	(92,142)	69,441
Series A Preferred Stock
Book to tax differences:
Cumulative Preferred Stock dividend- Called for redemption		$ (375)	0	0	375
Series B Preferred Stock
Book to tax differences:
Cumulative Preferred Stock dividend- Called for redemption	$ (1,375)		$ 0	$ 1,375	$ 0