Summary of Significant Accounting Policies - Offsetting of Financial Assets, Liabilities, and Collateral (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Assets
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet	[1]	$ 53,238	$ 35,701
Liabilities
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet	[1]	(16,072)	(163,424)
Total Liabilities
Gross Amounts of Recognized Assets (Liabilities)		(230,539)	(1,690,828)
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		(230,539)	(1,690,828)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		228,467	1,548,637
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged		1,061	141,260
Net Amount		(1,011)	(931)
Interest rate agreements
Assets
Gross Amounts of Recognized Assets (Liabilities)		19,951	19,020
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		19,951	19,020
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		0	(14,178)
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Received		(7,769)	(915)
Net Amount		12,182	3,927
Liabilities
Gross Amounts of Recognized Assets (Liabilities)			(148,765)
Gross Amounts Offset in Consolidated Balance Sheet			0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet			(148,765)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments			14,178
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged			134,587
Net Amount			0
TBAs
Assets
Gross Amounts of Recognized Assets (Liabilities)		18,260	5,755
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		18,260	5,755
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		(13,423)	(5,755)
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Received		(4,658)	0
Net Amount		179	0
Liabilities
Gross Amounts of Recognized Assets (Liabilities)		(15,495)	(13,359)
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		(15,495)	(13,359)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		13,423	5,755
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged		1,061	6,673
Net Amount		(1,011)	(931)
Futures
Assets
Gross Amounts of Recognized Assets (Liabilities)			137
Gross Amounts Offset in Consolidated Balance Sheet			0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet			137
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments			0
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Received			0
Net Amount			137
Interest Rate Agreement, TBAs, And Futures
Assets
Gross Amounts of Recognized Assets (Liabilities)		38,211	24,912
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		38,211	24,912
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		(13,423)	(19,933)
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Received		(12,427)	(915)
Net Amount		12,361	4,064
Loan warehouse debt
Loan warehouse debt and Security repurchase agreement
Gross Amounts of Recognized Assets (Liabilities)		(137,269)	(432,126)
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		(137,269)	(432,126)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		137,269	432,126
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged		0	0
Net Amount		0	0
Security repurchase agreements
Loan warehouse debt and Security repurchase agreement
Gross Amounts of Recognized Assets (Liabilities)		(77,775)	(1,096,578)
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		(77,775)	(1,096,578)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		77,775	1,096,578
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged		0	0
Net Amount		$ 0	$ 0

[1] Our consolidated balance sheets include assets of consolidated variable interest entities (“VIEs”) that can only be used to settle obligations of these VIEs and liabilities of consolidated VIEs for which creditors do not have recourse to Redwood Trust, Inc. or its affiliates. At December 31, 2020 and December 31, 2019, assets of consolidated VIEs totaled $8,141,069 and $11,931,869, respectively. At December 31, 2020 and December 31, 2019, liabilities of consolidated VIEs totaled $7,148,414 and $10,717,072, respectively. See Note 4 for further discussion.