Long-Term Debt - Additional Information (Details)				3 Months Ended
		Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2020 USD ($)
Debt Instrument [Line Items]
Repayments for FHLBC borrowings				$ 632,000,000
FHLBC stock		$ 43,393,000	$ 43,393,000	43,393,000
Existing debt		0	0	0
Accrued interest payable		4,000,000	6,000,000	4,000,000
Notional amount		9,206,372,000	13,589,356,000	9,206,372,000
Accrued interest payable	[1]	40,102,000	60,655,000	40,102,000
Facilities | MSR/AIOS Repurchase Facility
Debt Instrument [Line Items]
Maximum borrowing limit		50,000,000		50,000,000
Existing debt		30,000,000		30,000,000
Collateral amounts		$ 49,000,000		$ 49,000,000
Facilities | MSR/AIOS Repurchase Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate				2.75%
Convertible Debt | Exchangeable Senior Notes Due 2025
Debt Instrument [Line Items]
Debt Instrument interest rate		5.75%		5.75%
Unamortized debt issuance costs		$ 6,000,000		$ 6,000,000
Convertible notes		201,000,000		$ 201,000,000
Convertible senior notes conversion rate				0.0551967
Accrued interest payable		$ 6,000,000		$ 6,000,000
Convertible Debt | Senior Notes Due 2024
Debt Instrument [Line Items]
Debt Instrument interest rate		5.625%		5.625%
Unamortized debt issuance costs		$ 4,000,000		$ 4,000,000
Convertible notes		200,000,000		$ 200,000,000
Convertible senior notes conversion rate				0.0547645
Accrued interest payable		2,000,000		$ 2,000,000
Unamortized discount		$ 1,000,000		$ 1,000,000
Convertible Debt | Senior Notes Due 2023
Debt Instrument [Line Items]
Debt Instrument interest rate		4.75%		4.75%
Unamortized debt issuance costs		$ 4,000,000		$ 4,000,000
Convertible notes		245,000,000		$ 245,000,000
Convertible senior notes conversion rate				0.0543346
Accrued interest payable		1,000,000		$ 1,000,000
Trust Preferred Securities
Debt Instrument [Line Items]
Debt instrument face amount		100,000,000		100,000,000
Subordinated Notes
Debt Instrument [Line Items]
Debt instrument face amount		40,000,000		40,000,000
Trust Preferred Securities And Subordinated Notes
Debt Instrument [Line Items]
Accrued interest payable		1,000,000	1,000,000	1,000,000
FHLB Chicago | FHLB Member Subsidiary
Debt Instrument [Line Items]
Federal home loan bank advances outstanding		$ 1,370,000,000	$ 2,000,000,000.00	$ 1,370,000,000
Weighted average interest rate		1.31%	1.88%	1.31%
Weighted average maturity (in years)		5 years	6 years
Debt instrument face amount		$ 1,367,681,000		$ 1,367,681,000
FHLB Chicago | Redwood | Single-family rental loans held-for-investment | Residential Real Estate
Debt Instrument [Line Items]
Loans pledged as collateral under borrowing agreement with FHLBC			$ 248,000,000
FHLB Chicago | Redwood | Held-for-sale residential loans | Residential Real Estate
Debt Instrument [Line Items]
Loans pledged as collateral under borrowing agreement with FHLBC		1,430,000,000		1,430,000,000
FHLB Chicago | Redwood | Held-for-sale residential loans | Restricted cash
Debt Instrument [Line Items]
Loans pledged as collateral under borrowing agreement with FHLBC		$ 1,000,000		$ 1,000,000
Affiliated Entity | Long Term Non Market To market Recourse Debt Financing
Debt Instrument [Line Items]
Debt Instrument interest rate		4.21%		4.21%
Amount outstanding		$ 287,000,000		$ 287,000,000
Unamortized debt issuance costs		2,000,000		2,000,000
Debt instrument face amount		286,000,000		286,000,000
Pledged assets real estate pledged as collateral, at fair value		258,000,000		258,000,000
Affiliated Entity | Sequoia Choice | Long Term Non Market To market Recourse Debt Financing
Debt Instrument [Line Items]
Pledged assets real estate pledged as collateral, at fair value		155,000,000		155,000,000
Affiliated Entity | CAFL | Long Term Non Market To market Recourse Debt Financing
Debt Instrument [Line Items]
Pledged assets real estate pledged as collateral, at fair value		$ 103,000,000		$ 103,000,000

[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.