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Commitments and Contingencies - Additional Information (Details) $ in Thousands | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
May 31, 2020 USD ($) | Mar. 31, 2020 USD ($) | Sep. 30, 2019 partnership | Sep. 30, 2020 USD ($) | Dec. 31, 2020 USD ($) lease loan repurchase_request | Dec. 31, 2019 USD ($) repurchase_request loan | Dec. 31, 2018 USD ($) loan | Mar. 01, 2019 USD ($) | May 31, 2018 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Lessee, number of leases | lease |  |  |  |  |  | 8 |  |  |  |  |  |
Present value of remaining lease payments |  |  |  |  |  | $ 19,925 |  |  |  |  |  |
Operating lease expense |  |  |  |  |  | 4,000 | $ 3,000 | $ 2,000 |  |  |  |
Unamortized leasehold improvements |  |  |  |  |  | 3,000 |  |  |  |  |  |
Leasehold amortization expense |  |  |  |  |  | $ 500 | 400 | 200 |  |  |  |
Number of new leases | lease |  |  |  |  |  | 4 |  |  |  |  |  |
Lease liability |  |  |  |  |  | $ 16,687 | $ 13,443 |  |  |  |  |
Operating Lease, Liability, Statement of Financial Position [Extensible List] |  |  |  |  |  | us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent | us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent |  |  |  |  |
Operating lease right-of-use assets |  |  |  |  |  | $ 15,012 | $ 11,866 |  |  |  |  |
Weighted average remaining lease term |  |  |  |  |  | 7 years |  |  |  |  |  |
Discount rate |  |  |  |  |  | 4.90% |  |  |  |  |  |
Derivative liabilities | [1] |  |  |  |  | $ 16,072 | 163,424 |  |  |  |  |
Number of partnerships, committed to fund | partnership |  |  |  | 2 |  |  |  |  |  |  |  |
Contingent consideration |  |  |  |  |  | 0 | 28,484 |  |  |  |  |
Risk share income |  |  |  |  |  | 4,367 | 3,522 | $ 3,613 |  |  |  |
Principal amount outstanding on loans securitized |  |  |  |  |  | 172,748 | 524,928 |  |  |  |  |
Guarantee obligations |  |  |  |  |  | 10,039 | 14,009 |  |  |  |  |
Guarantee obligation, credit reserve |  |  |  |  |  | 5,000 |  |  |  |  |  |
SPE, assets |  |  |  |  |  | 46,000 | 48,000 |  |  |  |  |
SPE, liabilities |  |  |  |  |  | 10,000 | 14,000 |  |  |  |  |
Residential loan and MSR repurchase reserve |  |  |  |  |  | $ 8,631 | $ 4,268 |  |  |  |  |
Residential loans repurchase requests | repurchase_request |  |  |  |  |  | 10 | 15 |  |  |  |  |
Residential loans, number of loans repurchased | loan |  |  |  |  |  | 1 | 0 | 2 |  |  |  |
Residential loans repurchase provision (reversal) |  |  |  |  |  | $ 4,000 | $ 100 | $ 700 |  |  |  |
Residential loans repurchased during period |  |  |  |  |  | 100 | 0 | 0 |  |  |  |
Aggregate amount of loss contingency reserves |  |  |  |  | $ 2,000 |  |  |  |  |  |  |
Damages sought |  | $ 2,000 |  |  |  |  |  |  |  |  |  |
Residential Loan Seller Demands |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Expenses from litigation recorded |  |  |  |  | 10,000 |  |  |  |  |  |  |
Aggregate amount of accrual |  |  |  |  | $ 2,500 |  |  |  |  |  |  |
Residential Loans |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Principal amount outstanding on loans securitized |  |  |  |  |  | 172,748 | 525,069 |  |  |  |  |
Financing Receivables, Equal to Greater than 90 Days Past Due | Residential Loans |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loans past due |  |  |  |  |  | 1,882 | 747 |  |  |  |  |
Other Income |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Risk share income |  |  |  |  |  | 4,000 | 4,000 | 4,000 |  |  |  |
Mortgage Banking And Investment Activities |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Market valuation changes in fair value of guarantee asset |  |  |  |  |  | 1,000 | $ 200 | $ 400 |  |  |  |
Guarantee Obligations |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Original principal balance of loans sold subject to risk sharing agreement |  |  |  |  |  |  |  |  |  |  | $ 3,190,000 | $ 3,190,000
Potential future payments on risk sharing agreements |  |  |  |  |  | 44,000 |  |  |  |  |  |
Principal amount outstanding on loans securitized |  |  |  |  |  | $ 938,000 |  |  |  |  |  |
FICO credit score |  |  |  |  |  | 757 |  |  |  |  |  |
Loan to value ratio |  |  |  |  |  | 75.00% |  |  |  |  |  |
Guarantee Obligations | Residential Loans |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loans held as assets amount in foreclosure |  |  |  |  |  | $ 200 |  |  |  |  |  |
Guarantee Obligations | Financing Receivables, Equal to Greater than 90 Days Past Due |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Loans past due |  |  |  |  |  | 39,000 |  |  |  |  |  |
Commitment To Fund Residential Bridge Loan |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Commitments to fund temporary advances |  |  |  |  |  | 216,000 |  |  |  |  |  |
Derivative liabilities |  |  |  |  |  | 2,000 |  |  |  |  |  |
Commitment To Fund Temporary Advances On Residential Bridge Loans |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Commitments to fund temporary advances |  |  |  |  |  | 8,000 |  |  |  |  |  |
Shared home appreciation options |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Payments to acquire investments |  |  |  |  |  | 47,000 |  |  |  |  |  |
5 Arches, LLC |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration maximum amount |  |  |  |  |  |  |  |  | $ 27,000 | $ 29,000 |  |
Cash payment for contingent consideration |  |  | $ 11,000 |  |  |  |  |  |  |  |  |
Restricted stock awards |  |  | $ 3,000 |  |  |  |  |  |  |  |  |
Contingent consideration |  |  |  |  |  | $ 15,000 |  |  | $ 24,621 |  |  |
[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.

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