Summary of Significant Accounting Policies - Offsetting of Financial Assets, Liabilities, and Collateral (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Assets
Gross Amounts of Recognized Assets (Liabilities)		$ 90,717
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet	[1]	90,717	$ 35,701
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		(89,433)
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received) Pledged		(1,283)
Net Amount		1
Liabilities
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet	[1]	(114,614)	(163,424)
Total Liabilities
Gross Amounts of Recognized Assets (Liabilities)		(1,631,612)	(1,690,828)
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		(1,631,612)	(1,690,828)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		1,606,583	1,548,637
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received) Pledged		20,882	141,260
Net Amount		(4,147)	(931)
Interest rate agreements
Assets
Gross Amounts of Recognized Assets (Liabilities)			19,020
Gross Amounts Offset in Consolidated Balance Sheet			0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet			19,020
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments			(14,178)
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received) Pledged			(915)
Net Amount			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 (Received) Pledged			134,587
Net Amount			0
TBAs
Assets
Gross Amounts of Recognized Assets (Liabilities)		90,717	5,755
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		90,717	5,755
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		(89,433)	(5,755)
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received) Pledged		(1,283)	0
Net Amount		1	0
Liabilities
Gross Amounts of Recognized Assets (Liabilities)		(110,648)	(13,359)
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		(110,648)	(13,359)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		89,433	5,755
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received) Pledged		19,308	6,673
Net Amount		(1,907)	(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) Pledged			0
Net Amount			137
Interest Rate Agreement, TBAs, and Futures
Assets
Gross Amounts of Recognized Assets (Liabilities)			24,912
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet			24,912
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments			(19,933)
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received) Pledged			(915)
Net Amount			4,064
Loan warehouse debt
Loan warehouse debt and Security repurchase agreement
Gross Amounts of Recognized Assets (Liabilities)		(1,035,817)	(432,126)
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		(1,035,817)	(432,126)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		1,034,622	432,126
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received) Pledged		0	0
Net Amount		(1,195)
Security repurchase agreements
Loan warehouse debt and Security repurchase agreement
Gross Amounts of Recognized Assets (Liabilities)		(485,147)	(1,096,578)
Gross Amounts Offset in Consolidated Balance Sheet		0	0
Net Amounts of Assets (Liabilities) Presented in Consolidated Balance Sheet		(485,147)	(1,096,578)
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments		482,528	1,096,578
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received) Pledged		1,574	0
Net Amount		$ (1,045)	$ 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 March 31, 2020 and December 31, 2019, assets of consolidated VIEs totaled $7,470,706 and $11,931,869, respectively. At March 31, 2020 and December 31, 2019, liabilities of consolidated VIEs totaled $6,759,260 and $10,717,072, respectively. See Note 4 for further discussion.