CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net income (loss)	$ 1,751,134	$ (3,640,189)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities
Amortization of premiums and discounts of investments, net	(9,960)	618,800
Amortization of securitized debt premiums and discounts and deferred financing costs	(3,588)	(2,881)
Depreciation, amortization and other noncash expenses	8,408	7,684
Net (gains) losses on disposal of investments and other	65,786	(206,583)
Net (gains) losses on investments and derivatives	(1,353,321)	3,749,018
Net (gains) losses on business divestitures	249,563	0
Income from unconsolidated joint ventures	(1,025)	(370)
Loan loss provision (reversal)	(139,620)	99,326
Payments on purchases of loans held for sale	(969)	(54,820)
Proceeds from sales and repayments of loans held for sale	3,067	61,664
Net receipts (payments) on derivatives	435,107	(2,680,933)
Net change in
Other assets	(31,236)	105,636
Interest receivable	9,386	115,341
Interest payable	(89,000)	(215,030)
Other liabilities	170,818	20,075
Net cash provided by (used in) operating activities	1,064,550	(2,023,262)
Cash flows from investing activities
Payments on purchases of securities	(5,478,414)	(11,526,904)
Proceeds from sales of securities	2,852,764	41,132,114
Principal payments on securities	4,986,008	4,900,580
Payments on purchases and origination of loans	(651,397)	(1,148,574)
Proceeds from sales of loans	46,171	271,007
Principal payments on loans	683,451	471,384
Investments in real estate	(746)	(1,159)
Proceeds from sales of real estate	4,265	0
Proceeds from reverse repurchase agreements	8,634,313	27,150,000
Payments on reverse repurchase agreements	(8,634,313)	(27,150,000)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	290	6,017
Net cash provided by (used in) investing activities	2,442,392	34,104,465
Cash flows from financing activities
Proceeds from repurchase agreements and other secured financing	534,607,127	1,126,771,986
Payments on repurchase agreements and other secured financing	(537,932,992)	(1,158,603,746)
Proceeds from issuances of securitized debt	251,379	1,394,065
Principal payments on securitized debt	(357,224)	(276,551)
Proceeds from partcipations issued	183,067	0
Payments on repurchases of participations issued	(40,434)	0
Principal payments on participations issued	(1,293)	0
Net principal receipts (payments) on mortgages payable	(330)	(811)
Net contributions (distributions) from (to) noncontrolling interests	(2,013)	(288)
Settlement of stock-based awards in satisfaction of withholding tax requirements	(596)	0
Dividends paid	(334,543)	(393,066)
Net cash provided by (used in) financing activities	(3,627,852)	(31,108,411)
Net (decrease) increase in cash and cash equivalents	(120,910)	972,792
Cash and cash equivalents including cash pledged as collateral, beginning of period	1,243,703	1,850,729
Cash and cash equivalents including cash pledged as collateral, end of period	1,122,793	2,823,521
Supplemental disclosure of cash flow information
Interest received	783,900	1,260,159
Dividends received	33	2,116
Interest paid (excluding interest paid on interest rate swaps)	116,028	575,973
Net interest paid on interest rate swaps	133,628	171,965
Taxes received (paid)	0	52
Noncash investing and financing activities
Receivable for unsettled trades	144,918	1,006,853
Payable for unsettled trades	1,070,080	923,552
Net change in unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment	(1,372,104)	983,180
Dividends declared, not yet paid	$ 307,671	$ 357,606