CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019
Cash Flows From Operating Activities:
Net Income (Loss)		$ (636,142)	$ 120,040
Adjustments to reconcile net (loss) income to net cash used in operating activities:
Amortization of premiums, discounts, and securities issuance costs, net		6,213	(3,486)
Depreciation and amortization of non-financial assets		13,166	5,673
Originations of held-for-sale loans		(654,820)	(124,392)
Purchases of held-for-sale loans		(2,893,246)	(4,002,509)
Proceeds from sales of held-for-sale loans		3,224,526	2,971,811
Principal payments on held-for-sale loans		53,677	77,100
Net settlements of derivatives		(187,130)	(32,902)
Non-cash equity award compensation expense		11,146	10,552
Goodwill impairment expense		88,675	0
Market valuation adjustments		606,764	(62,720)
Realized gains, net		(30,419)	(18,227)
Net change in:
Accrued interest receivable and other assets		304,147	(141,197)
Accrued interest payable and accrued expenses and other liabilities		(82,489)	(1,049)
Net cash used in operating activities		(175,932)	(1,201,306)
Cash Flows From Investing Activities:
Originations of loan investments		(327,494)	(171,915)
Purchases of loan investment		0	(49,489)
Proceeds from sales of loan investments		1,574,160	9,422
Principal payments on loan investments		1,652,418	1,091,652
Purchases of real estate securities		(106,422)	(309,839)
Sales of multifamily securities held in consolidated securitization trusts		142,990	0
Proceeds from sales of real estate securities		634,709	487,469
Principal payments on real estate securities		19,446	62,711
Purchases of servicer advance investments		(179,419)	(69,610)
Principal repayments from servicer advance investments		83,124	150,512
Acquisition of 5 Arches, net of cash acquired		0	(3,714)
Net investment in participation in loan warehouse facility		0	38,209
Net investment in multifamily loan fund		40,898	(33,090)
Other investing activities, net		(19,865)	(24,989)
Net cash provided by investing activities		3,514,545	915,516
Cash Flows From Financing Activities:
Proceeds from borrowings on short-term debt		3,981,572	4,009,083
Repayments on short-term debt		(5,828,972)	(4,435,823)
Proceeds from issuance of asset-backed securities		1,343,845	1,020,136
Repayments on asset-backed securities issued		(1,037,546)	(720,651)
Proceeds from issuance of long-term debt		1,251,850	387,053
Deferred long-term debt issuance costs paid		(9,526)	(7,023)
Repayments on long-term debt		(2,640,007)	0
Net settlements of derivatives		(84,336)	0
Net proceeds from issuance of common stock		5,791	426,970
Net payments on repurchase of common stock		(21,659)	0
Taxes paid on equity award distributions		(3,009)	0
Dividends paid		(67,821)	(94,286)
Other financing activities, net		4,650	1,400
Net cash (used in) provided by financing activities		(3,105,168)	586,859
Net increase in cash, cash equivalents and restricted cash		233,445	301,069
Cash, cash equivalents and restricted cash at beginning of period	[1]	290,833	205,077
Cash, cash equivalents, and restricted cash at end of period	[1]	524,278	506,146
Cash paid during the period for:
Interest		364,875	319,036
Taxes		218	6,977
Supplemental Noncash Information:
Real estate securities retained from loan securitizations		46,560	7,759
Retention of mortgage servicing rights from loan securitizations and sales		0	868
Consolidation of residential loans held in securitization trusts		0	1,190,995
Consolidation of residential ABS		0	997,783
Consolidation of multifamily loans held in securitization trusts		(3,849,779)	1,481,554
Consolidation of multifamily ABS		(3,706,789)	1,408,002
Transfers from loans held-for-sale to loans held-for-investment		770,754	1,361,015
Transfers from residential loans to real estate owned		12,547	5,280
Right-of-use asset obtained in exchange for operating lease liability		5,362	13,016
Reduction in operating lease liability due to lease modification		1,466	0
Residential loans
Cash Flows From Investing Activities:
Purchases of multifamily securities held in consolidated securitization trusts		0	(193,212)
Multifamily loans
Cash Flows From Investing Activities:
Purchases of multifamily securities held in consolidated securitization trusts		$ 0	$ (68,601)

[1] Cash, cash equivalents, and restricted cash at September 30, 2020 includes cash and cash equivalents of $451 million and restricted cash of $74 million, and at December 31, 2019 includes cash and cash equivalents of $197 million and restricted cash of $94 million.