CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Cash Flows From Operating Activities:
Net income (loss)	$ 2,170	$ (186,145)	$ 95,560	$ (610,266)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
(Accretion) amortization of investment discounts/premiums, net			16,985	68,632
Accretion (amortization) of deferred financing costs, debt issuance costs, and Securitized debt discounts/premiums, net			27,228	(2,799)
Net unrealized losses (gains) on derivatives	(17)	(10,307)	(9,460)	(8,689)
Proceeds (payments) for derivative settlements			(20,509)	(6,200)
Margin (paid) received on derivatives			78,248	(2,301)
Net unrealized losses (gains) on financial instruments at fair value	43,988	239,513	(27,558)	848,925
Net realized losses (gains) on sales of investments	460	37,031	27,482	37,031
Other investment (gains) losses	(2,381)	462	(2,077)	(517)
Net increase (decrease) in provision for credit losses			9,041	3,203
(Gain) loss on extinguishment of debt	0	0	(6,348)	2,897
Equity-based compensation expense			6,439	4,731
Changes in operating assets:
Decrease (increase) in accrued interest receivable, net			(11,047)	164
Decrease (increase) in other assets			(13,121)	(57,260)
Changes in operating liabilities:
Increase (decrease) in accounts payable and other liabilities			6,105	15,079
Increase (decrease) in accrued interest payable, net			4,974	6,657
Net cash provided by (used in) operating activities			181,942	299,287
Cash Flows From Investing Activities:
Net cash provided by (used in) investing activities			174,965	655,521
Cash Flows From Financing Activities:
Proceeds from secured financing agreements			22,272,760	28,538,545
Payments on secured financing agreements			(23,099,486)	(28,982,125)
Payments on repurchase of common stock			(33,101)	(48,886)
Proceeds from securitized debt borrowings, collateralized by Loans held for investment			2,046,620	1,029,050
Payments on securitized debt borrowings, collateralized by Loans held for investment			(1,461,868)	(1,498,622)
Payments on securitized debt borrowings, collateralized by Non-Agency RMBS			(52)	(2,769)
Common dividends paid			(152,476)	(234,225)
Preferred dividends paid			(55,313)	(55,283)
Net cash provided by (used in) financing activities			(482,916)	(1,254,315)
Net increase (decrease) in cash and cash equivalents			(126,009)	(299,507)
Cash and cash equivalents at beginning of period			264,600	385,741	$ 385,741
Cash and cash equivalents at end of period	138,591	86,234	138,591	86,234	264,600
Supplemental disclosure of cash flow information:
Interest received			587,637	654,650
Interest paid			350,787	223,845
Non-cash investing activities:
Receivable for investments sold			0	14,118
Payable for investments purchased			6,237	644,120
Net change in unrealized gain (loss) on available-for sale securities	(29,447)	(61,526)	(49,431)	(160,850)
Non-cash financing activities:
Dividends declared, not yet paid			49,881	63,860
Variable Interest Entities, Primary Beneficiary
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Net increase (decrease) in provision for credit losses	$ 1,560	$ (2,284)	3,519	859
Variable Interest Entities, Primary Beneficiary | Securitized debt at fair value, collateralized by loans held for investment
Transfer of investments due to consolidation
Securitized debt at fair value, collateralized by loans held for investment			0	774,514
Agency MBS portfolio
Cash Flows From Investing Activities:
Purchases			(2,006)	(57,473)
Sales			285,709	4,187
Principal payments			677	253,131
Non-agency RMBS Portfolio
Cash Flows From Investing Activities:
Purchases			(3,954)	(23,000)
Sales			0	0
Principal payments			64,796	159,151
Transfer of investments due to consolidation
Non-Agency RMBS, at fair value			0	(218,276)
Loans held for investment
Cash Flows From Investing Activities:
Sales			2,611	0
Principal payments			1,087,319	1,764,067
Purchases			(1,260,187)	(1,444,542)
Loans Held for Investment at Fair Value | Variable Interest Entities, Primary Beneficiary
Transfer of investments due to consolidation
Loans held for investment, at fair value			$ 0	$ 1,047,838	$ 1,047,838