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	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Variable Interest Entity [Line Items]
Proceeds from new transfers	$ 1,610,761	$ 352,371
MSR fees received	2,690	3,060
Funding of compensating interest, net	(92)	(90)
Cash flows received on retained securities	$ 6,581	$ 7,546