Principles of Consolidation - Schedule of Unconsolidated VIEs Sponsored by Redwood (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024
Assets, Fair Value Disclosure [Abstract]
Subordinate securities, classified as AFS			$ 287,557	$ 211,474
Interest-only, senior and subordinate securities, classified as trading			135,459	193,749
Mortgage servicing rights	[1]		302,230	297,683
Commitment To Fund Legacy Residential Bridge Loans
Assets, Fair Value Disclosure [Abstract]
Funding commitment		$ 35,000	35,000
Payments for other commitments		10,000	10,000
Additional funding commitments		$ 25,000	25,000
Variable Interest Entity, Not Primary Beneficiary
Assets, Fair Value Disclosure [Abstract]
Strategic investments, equity method			10,263	0
Funding commitment			35,000	0
Maximum loss exposure			374,803	140,588
Variable Interest Entity, Not Primary Beneficiary | Subordinate securities, classified as AFS
Assets, Fair Value Disclosure [Abstract]
Subordinate securities, classified as AFS			283,768	91,221
Interest-only, senior and subordinate securities, classified as trading | Variable Interest Entity, Not Primary Beneficiary
Assets, Fair Value Disclosure [Abstract]
Interest-only, senior and subordinate securities, classified as trading			33,743	36,811
Mortgage servicing rights | Variable Interest Entity, Not Primary Beneficiary
Assets, Fair Value Disclosure [Abstract]
Mortgage servicing rights			$ 12,029	$ 12,556

[1] Our consolidated balance sheets include assets of 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, 2025 and 2024, assets of consolidated VIEs totaled $18,927,094 and $14,654,942, respectively. At December 31, 2025 and 2024, liabilities of consolidated VIEs totaled $17,850,175 and $13,620,239, respectively. See Note 15 for further discussion.