CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income (loss)	$ (1,638,457)	$ 1,726,420	$ 2,396,280
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities
Amortization of premiums and discounts of investments, net	185,728	87,154	784,110
Amortization of securitized debt premiums and discounts and deferred financing costs	13,824	(4,733)	(6,620)
Depreciation, amortization and other noncash expenses	24,806	20,506	24,636
Net (gains) losses on investments and derivatives	3,310,579	109,443	(1,204,830)
Business divestiture-related (gains) losses	0	40,258	278,559
Income (loss) from unconsolidated joint ventures	10,270	(11,454)	12,181
Loan loss provision (reversal)	(219)	(20,660)	(145,066)
Payments on purchases of loans held for sale	0	0	(51,403)
Proceeds from sales and repayments of loans held for sale	1,577	4,597	90,020
Proceeds from U.S. Treasury securities	2,015,608	0	0
Net receipts (payments) on derivatives	(862,032)	3,643,954	932,867
Net change in
Other assets	(136,804)	(11,437)	31,044
Interest receivable	(585,817)	(403,613)	32,926
Interest payable	(37,343)	233,753	(99,590)
Other liabilities	65,483	(41,777)	1,725
Net cash provided by (used in) operating activities	2,367,203	5,372,411	3,076,839
Cash flows from investing activities
Payments on purchases of securities	(41,036,338)	(45,474,466)	(22,344,751)
Proceeds from sales of securities	31,259,983	25,055,929	11,670,321
Principal payments on securities	6,153,217	9,541,036	18,742,951
Payments on purchases and origination of loans	(5,503,696)	(6,137,067)	(7,715,200)
Proceeds from sales of loans	21,242	1,930,367	1,213,745
Principal payments on loans	1,086,508	1,562,308	2,610,912
Payments on purchases of MSR	(396,806)	(1,009,349)	(473,035)
Proceeds from sales of MSR	0	9,085	82,175
Payments on purchases of interests in MSR	0	(4,913)	(65,107)
Investments in real estate	0	0	(2,329)
Proceeds from sales of real estate	0	0	53,910
Proceeds from reverse repurchase agreements	128,615,235	24,500,024	16,734,313
Payments on reverse repurchase agreements	(128,615,235)	(24,500,024)	(16,734,313)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	0	0	290
Proceeds from sale of equity securities	0	0	6,957
Net proceeds from business divestiture	0	0	1,118,440
Net cash provided by (used in) investing activities	(8,415,890)	(14,527,070)	4,899,279
Cash flows from financing activities
Proceeds from repurchase agreements and other secured financing	5,351,050,481	3,571,043,066	2,288,704,788
Payments on repurchase agreements and other secured financing	(5,348,111,535)	(3,566,953,367)	(2,298,775,005)
Proceeds from issuances of securitized debt	4,480,804	5,473,311	3,719,027
Principal payments on securitized debt	(944,163)	(1,234,090)	(1,716,196)
Payments on purchases of securitized debt	(2,504)	(8,495)	0
Payment of deferred financing cost	(4,012)	0	(9,279)
Net proceeds from stock offerings, direct purchases and dividend reinvestments	673,693	2,636,000	552,215
Proceeds from participations issued	2,007,464	1,908,204	1,847,821
Payments on repurchases of participations issued	(1,674,650)	(1,973,666)	(818,575)
Principal payments on participations issued	(52,635)	(50,712)	(23,374)
Net principal receipts (payments) on mortgages payable	0	0	(2,237)
Net contributions (distributions) from (to) noncontrolling interests	(14,399)	72,389	5,635
Settlement of stock-based awards in satisfaction of withholding tax requirements	(6,661)	(4,108)	(2,830)
Dividends paid	(1,517,762)	(1,519,249)	(1,359,721)
Net cash provided by (used in) financing activities	5,884,121	9,389,283	(7,877,731)
Net (decrease) increase in cash and cash equivalents	(164,566)	234,624	98,387
Cash and cash equivalents including cash pledged as collateral, beginning of period	1,576,714	1,342,090	1,243,703
Cash and cash equivalents including cash pledged as collateral, end of period	1,412,148	1,576,714	1,342,090
Supplemental disclosure of cash flow information
Interest received	3,278,519	2,459,012	2,701,381
Dividends received	0	0	51
Interest paid (excluding interest paid on interest rate swaps)	3,551,873	866,829	269,244
Net interest received (paid) on interest rate swaps	1,306,551	15,621	(340,738)
Taxes received (paid)	1,104	(492)	(3,797)
Noncash investing and financing activities
Receivable for unsettled trades	2,710,224	575,091	2,656
Payable for unsettled trades	3,249,389	1,157,846	147,908
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	2,373,496	(4,667,306)	(2,415,925)
Dividends declared, not yet paid	325,052	412,113	321,142
Derecognition of assets of consolidated VIEs	0	424,005	3,075,961
Derecognition of securitized debt of consolidated VIEs	0	391,928	2,506,799
Derecognition of mortgages payable	$ 0	$ 0	$ 314,485