Principles of Consolidation - Cash Flows Related to Unconsolidated Variable Interest Entity's Sponsored by Redwood (Details) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Proceeds from new transfers	$ 2,276,521	$ 1,912,334
MSR fees received	9,749	11,857
Funding of compensating interest, net	(405)	(368)
Cash flows received on retained securities	$ 24,172	$ 27,045