Summary of Significant Accounting Policies (Policies)	3 Months Ended
Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of PresentationThe consolidated financial statements presented herein are at March 31, 2023 and December 31, 2022, and for the three months ended March 31, 2023 and 2022. These interim unaudited consolidated financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission ("SEC"). Certain information and note disclosures normally included in our annual financial statements prepared in accordance with U.S. generally accepted accounting principles ("GAAP") — as prescribed by the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) — have been condensed or omitted in these interim financial statements according to these SEC rules and regulations. Management believes that the disclosures included in these interim financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the company's Annual Report on Form 10-K for the year ended December 31, 2022. In the opinion of management, all normal and recurring adjustments have been made to present fairly the financial condition of the Company at March 31, 2023 and results of operations for all periods presented. The results of operations for the three months ended March 31, 2023 should not be construed as indicative of the results to be expected for the full year.
Principles of Consolidation	Principles of Consolidation In accordance with GAAP, we determine whether we must consolidate transferred financial assets and variable interest entities (“VIEs”) for financial reporting purposes. We currently consolidate the assets and liabilities of certain Sequoia securitization entities issued prior to 2012 ("Legacy Sequoia"), certain entities formed during and after 2012 in connection with the securitization of Redwood Select prime loans and Redwood Choice expanded-prime loans ("Sequoia"), entities formed in connection with the securitization of CoreVest BPL term and bridge loans ("CAFL") and an entity formed in connection with the securitization of home equity investment contracts ("HEIs"). We also consolidate the assets and liabilities of certain Freddie Mac K-Series and Freddie Mac Seasoned Loans Structured Transaction ("SLST") securitizations in which we have invested. Each securitization entity is independent of Redwood and of each other and the assets and liabilities are not owned by and are not legal obligations of Redwood Trust, Inc. Our exposure to these entities is primarily through the financial interests we have purchased or retained, although for certain entities we are exposed to financial risks associated with our role as a sponsor or co-sponsor, servicing administrator, collateral administrator or depositor of these entities or as a result of our having sold assets directly or indirectly to these entities. For financial reporting purposes, the underlying loans owned at the consolidated Legacy Sequoia, Sequoia and Freddie Mac SLST entities are shown under Residential loans held-for-investment, at fair value, the underlying loans at the consolidated Freddie Mac K-Series entity are shown under Consolidated Agency multifamily loans, at fair value, the underlying BPL term and bridge loans at the consolidated CAFL entities are shown under Business purpose loans held-for-investment, at fair value, and the underlying HEIs at the consolidated HEI securitization entity are shown under Home equity investments, at fair value on our consolidated balance sheets. The asset-backed securities (“ABS”) issued to third parties by these entities are shown under ABS issued. In our consolidated statements of income, we record interest income on the loans owned at these entities and interest expense on the ABS issued by these entities as well as fair value changes, other income and expenses associated with these entities' activities. See Note 15 for further discussion on ABS issued. We also consolidate two partnerships ("Servicing Investment" entities) through which we have invested in servicing-related assets. We maintain an 80% ownership interest in each entity and have determined that we are the primary beneficiary of these partnerships. See Note 4 for further discussion on principles of consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements requires us to make a number of significant estimates. These include estimates of fair value of certain assets and liabilities, amounts and timing of credit losses, prepayment rates, and other estimates that affect the reported amounts of certain assets and liabilities as of the date of the consolidated financial statements and the reported amounts of certain revenues and expenses during the reported periods. It is likely that changes in these estimates (e.g., valuation changes due to supply and demand, credit performance, prepayments, interest rates, or other reasons) will occur in the near term. Our estimates are inherently subjective in nature and actual results could differ from our estimates and the differences could be material.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Newly Adopted Accounting Standard Updates ("ASUs") In March 2022, the FASB issued ASU 2022-02, "Financial Instruments-Credit Losses (Topic 326), Troubled Debt Restructurings and Vintage Disclosures." ASU 2022-02 addresses areas identified by the FASB as part of its post-implementation review of the credit losses standard (ASU 2016-13) that introduced the current expected credit loss ("CECL") model. The amendments eliminate the accounting guidance for troubled debt restructurings by creditors that have adopted the CECL model and enhance the disclosure requirements for loan refinancings and restructurings made with borrowers experiencing financial difficulty. In addition, the amendments require a public business entity to disclose current-period gross writeoffs for financing receivables and net investment in leases by year of origination in the vintage disclosures. This new guidance was effective for fiscal years beginning after December 31, 2022. We adopted this guidance in the first quarter of 2023, which did not have a material impact on our consolidated financial statements. In March 2022, the FASB issued ASU 2022-01, "Derivatives and Hedging (Topic 815), Fair Value Hedging - Portfolio Layer Method," which will expand companies' abilities to hedge the benchmark interest rate risk of portfolios of financial assets (or beneficial interests) in a fair value hedge. The ASU expands the use of the portfolio layer method (previously referred to as the last-of-layer method) to allow multiple hedges of a single closed portfolio of assets using spot starting, forward starting, and amortizing-notional swaps. The ASU also permits both prepayable and non-prepayable financial assets to be included in the closed portfolio of assets hedged in a portfolio layer hedge. The ASU further requires that basis adjustments not be allocated to individual assets for active portfolio layer method hedges, but rather be maintained on the closed portfolio of assets as a whole. This new guidance was effective for fiscal years beginning after December 31, 2022. We adopted this guidance in the first quarter of 2023, which did not have a material impact on our consolidated financial statements. In December 2022, the FASB issued ASU 2022-06, "Reference Rate Reform (Topic 848) - Deferral of the Sunset Date of Topic 848." This new guidance defers the sunset date of Topic 848 from December 31, 2022, to December 31, 2024, after which entities will no longer be permitted to apply the relief in Topic 848. The objective of the guidance in Topic 848 is to provide temporary relief during the transition period. Through March 31, 2023, we have not elected to apply the optional expedients and exceptions to any of our existing contracts, hedging relationships, or other transactions. Other Recent Accounting Pronouncements Pending Adoption In June 2022, the FASB issued ASU 2022-03, “Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions.” ASU 2022-03 was issued (1) to clarify the guidance in Topic 820, Fair Value Measurement, when measuring the fair value of an equity security subject to contractual restrictions that prohibit the sale of an equity security, (2) to amend a related illustrative example, and (3) to introduce new disclosure requirements for equity securities subject to contractual sale restrictions that are measured at fair value in accordance with Topic 820. The amendments in this update are effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted. We are evaluating the accounting and disclosure requirements of ASU 2022-03 and we plan to adopt this new guidance by the required date. We do not anticipate that this update will have a material impact on our financial statements. We have an established cross-functional group that has evaluated our exposure to LIBOR, reviewed relevant contracts and has monitored regulatory updates to assess the potential impact to our business, processes and technology from the ultimate full cessation of LIBOR in 2023, and has established a LIBOR transition plan to facilitate an orderly transition to alternative reference rates. We continue to remain on track with our LIBOR transition plan, which requires different solutions depending on the underlying asset or liability with LIBOR exposure. At March 31, 2023, our primary LIBOR exposure included the following: $742 million of bridge loans and $140 million of trust preferred securities and subordinated debt. In 2022, we began benchmarking all newly originated BPL bridge loans to SOFR. The LIBOR-indexed BPL bridge loans we have outstanding have fallback provisions for benchmark replacement. Additionally, as a result of legislation that was passed in the state of New York, our trust preferred securities and subordinated notes are expected to convert to SOFR upon the cessation of LIBOR.
Balance Sheet Netting	Balance Sheet Netting Certain of our derivatives and short-term debt are subject to master netting arrangements or similar agreements. Under GAAP, in certain circumstances we may elect to present certain financial assets, liabilities and related collateral subject to master netting arrangements in a net position on our consolidated balance sheets. However, we do not report any of these financial assets or liabilities on a net basis, and instead present them on a gross basis on our consolidated balance sheets.

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2023

Basis of PresentationThe consolidated financial statements presented herein are at March 31, 2023 and December 31, 2022, and for the three months ended March 31, 2023 and 2022. These interim unaudited consolidated financial statements have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission ("SEC"). Certain information and note disclosures normally included in our annual financial statements prepared in accordance with U.S. generally accepted accounting principles ("GAAP") — as prescribed by the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) — have been condensed or omitted in these interim financial statements according to these SEC rules and regulations. Management believes that the disclosures included in these interim financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the company's Annual Report on Form 10-K for the year ended December 31, 2022. In the opinion of management, all normal and recurring adjustments have been made to present fairly the financial condition of the Company at March 31, 2023 and results of operations for all periods presented. The results of operations for the three months ended March 31, 2023 should not be construed as indicative of the results to be expected for the full year.

Principles of Consolidation

In accordance with GAAP, we determine whether we must consolidate transferred financial assets and variable interest entities (“VIEs”) for financial reporting purposes. We currently consolidate the assets and liabilities of certain Sequoia securitization entities issued prior to 2012 ("Legacy Sequoia"), certain entities formed during and after 2012 in connection with the securitization of Redwood Select prime loans and Redwood Choice expanded-prime loans ("Sequoia"), entities formed in connection with the securitization of CoreVest BPL term and bridge loans ("CAFL") and an entity formed in connection with the securitization of home equity investment contracts ("HEIs"). We also consolidate the assets and liabilities of certain Freddie Mac K-Series and Freddie Mac Seasoned Loans Structured Transaction ("SLST") securitizations in which we have invested. Each securitization entity is independent of Redwood and of each other and the assets and liabilities are not owned by and are not legal obligations of Redwood Trust, Inc. Our exposure to these entities is primarily through the financial interests we have purchased or retained, although for certain entities we are exposed to financial risks associated with our role as a sponsor or co-sponsor, servicing administrator, collateral administrator or depositor of these entities or as a result of our having sold assets directly or indirectly to these entities.

For financial reporting purposes, the underlying loans owned at the consolidated Legacy Sequoia, Sequoia and Freddie Mac SLST entities are shown under Residential loans held-for-investment, at fair value, the underlying loans at the consolidated Freddie Mac K-Series entity are shown under Consolidated Agency multifamily loans, at fair value, the underlying BPL term and bridge loans at the consolidated CAFL entities are shown under Business purpose loans held-for-investment, at fair value, and the underlying HEIs at the consolidated HEI securitization entity are shown under Home equity investments, at fair value on our consolidated balance sheets. The asset-backed securities (“ABS”) issued to third parties by these entities are shown under ABS issued. In our consolidated statements of income, we record interest income on the loans owned at these entities and interest expense on the ABS issued by these entities as well as fair value changes, other income and expenses associated with these entities' activities. See Note 15 for further discussion on ABS issued.

We also consolidate two partnerships ("Servicing Investment" entities) through which we have invested in servicing-related assets. We maintain an 80% ownership interest in each entity and have determined that we are the primary beneficiary of these partnerships.

See Note 4 for further discussion on principles of consolidation.

Use of Estimates

The preparation of financial statements requires us to make a number of significant estimates. These include estimates of fair value of certain assets and liabilities, amounts and timing of credit losses, prepayment rates, and other estimates that affect the reported amounts of certain assets and liabilities as of the date of the consolidated financial statements and the reported amounts of certain revenues and expenses during the reported periods. It is likely that changes in these estimates (e.g., valuation changes due to supply and demand, credit performance, prepayments, interest rates, or other reasons) will occur in the near term. Our estimates are inherently subjective in nature and actual results could differ from our estimates and the differences could be material.

Recent Accounting Pronouncements

Newly Adopted Accounting Standard Updates ("ASUs")

In March 2022, the FASB issued ASU 2022-02, "Financial Instruments-Credit Losses (Topic 326), Troubled Debt Restructurings and Vintage Disclosures." ASU 2022-02 addresses areas identified by the FASB as part of its post-implementation review of the credit losses standard (ASU 2016-13) that introduced the current expected credit loss ("CECL") model. The amendments eliminate the accounting guidance for troubled debt restructurings by creditors that have adopted the CECL model and enhance the disclosure requirements for loan refinancings and restructurings made with borrowers experiencing financial difficulty. In addition, the amendments require a public business entity to disclose current-period gross writeoffs for financing receivables and net investment in leases by year of origination in the vintage disclosures. This new guidance was effective for fiscal years beginning after December 31, 2022. We adopted this guidance in the first quarter of 2023, which did not have a material impact on our consolidated financial statements.

In March 2022, the FASB issued ASU 2022-01, "Derivatives and Hedging (Topic 815), Fair Value Hedging - Portfolio Layer Method," which will expand companies' abilities to hedge the benchmark interest rate risk of portfolios of financial assets (or beneficial interests) in a fair value hedge. The ASU expands the use of the portfolio layer method (previously referred to as the last-of-layer method) to allow multiple hedges of a single closed portfolio of assets using spot starting, forward starting, and amortizing-notional swaps. The ASU also permits both prepayable and non-prepayable financial assets to be included in the closed portfolio of assets hedged in a portfolio layer hedge. The ASU further requires that basis adjustments not be allocated to individual assets for active portfolio layer method hedges, but rather be maintained on the closed portfolio of assets as a whole. This new guidance was effective for fiscal years beginning after December 31, 2022. We adopted this guidance in the first quarter of 2023, which did not have a material impact on our consolidated financial statements.

In December 2022, the FASB issued ASU 2022-06, "Reference Rate Reform (Topic 848) - Deferral of the Sunset Date of Topic 848." This new guidance defers the sunset date of Topic 848 from December 31, 2022, to December 31, 2024, after which entities will no longer be permitted to apply the relief in Topic 848. The objective of the guidance in Topic 848 is to provide temporary relief during the transition period. Through March 31, 2023, we have not elected to apply the optional expedients and exceptions to any of our existing contracts, hedging relationships, or other transactions.

Other Recent Accounting Pronouncements Pending Adoption

In June 2022, the FASB issued ASU 2022-03, “Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions.” ASU 2022-03 was issued (1) to clarify the guidance in Topic 820, Fair Value Measurement, when measuring the fair value of an equity security subject to contractual restrictions that prohibit the sale of an equity security, (2) to amend a related illustrative example, and (3) to introduce new disclosure requirements for equity securities subject to contractual sale restrictions that are measured at fair value in accordance with Topic 820. The amendments in this update are effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted. We are evaluating the accounting and disclosure requirements of ASU 2022-03 and we plan to adopt this new guidance by the required date. We do not anticipate that this update will have a material impact on our financial statements.

We have an established cross-functional group that has evaluated our exposure to LIBOR, reviewed relevant contracts and has monitored regulatory updates to assess the potential impact to our business, processes and technology from the ultimate full cessation of LIBOR in 2023, and has established a LIBOR transition plan to facilitate an orderly transition to alternative reference rates. We continue to remain on track with our LIBOR transition plan, which requires different solutions depending on the underlying asset or liability with LIBOR exposure. At March 31, 2023, our primary LIBOR exposure included the following: $742 million of bridge loans and $140 million of trust preferred securities and subordinated debt. In 2022, we began benchmarking all newly originated BPL bridge loans to SOFR. The LIBOR-indexed BPL bridge loans we have outstanding have fallback provisions for benchmark replacement. Additionally, as a result of legislation that was passed in the state of New York, our trust preferred securities and subordinated notes are expected to convert to SOFR upon the cessation of LIBOR.

Balance Sheet Netting

Balance Sheet Netting Certain of our derivatives and short-term debt are subject to master netting arrangements or similar agreements. Under GAAP, in certain circumstances we may elect to present certain financial assets, liabilities and related collateral subject to master netting arrangements in a net position on our consolidated balance sheets. However, we do not report any of these financial assets or liabilities on a net basis, and instead present them on a gross basis on our consolidated balance sheets.