Principles of Consolidation - Securitization Activity Related to Unconsolidated Variable Interest Entity's Sponsored by Redwood (Details) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Variable Interest Entity [Line Items]
Principal balance of loans transferred	$ 0	$ 366,999	$ 1,573,703	$ 1,116,092
Trading securities retained, at fair value
Variable Interest Entity [Line Items]
Securities retained, at fair value	0	1,228	43,362	4,736
AFS securities retained, at fair value
Variable Interest Entity [Line Items]
Securities retained, at fair value	$ 0	$ 1,069	$ 3,198	$ 3,023