Principles of Consolidation - Summary of Unconsolidated Variable Interest Entity's Sponsored by Redwood (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Debt securities, available for sale	$ 218,458	$ 239,334
Variable Interest Entity, Not Primary Beneficiary
Assets
Maximum loss exposure	165,870	269,328
Assets transferred:
Principal balance of loans outstanding	7,728,432	10,299,442
Principal balance of loans 30+ days delinquent	138,029	41,809
Interest-only, senior and subordinate securities, classified as trading \| Variable Interest Entity, Not Primary Beneficiary
Assets
Debt securities, trading	20,982	88,425
Subordinate securities, classified as AFS \| Variable Interest Entity, Not Primary Beneficiary
Assets
Debt securities, available for sale	136,475	140,649
Mortgage servicing rights
Assets
Servicing asset, fair value	8,815	42,224
Mortgage servicing rights \| Variable Interest Entity, Not Primary Beneficiary
Assets
Servicing asset, fair value	$ 8,413	$ 40,254

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