Principles of Consolidation - Key Assumptions and Sensitivity Analysis for Assets Retained from Unconsolidated Variable Interest Entity's Sponsored by Redwood (Details) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Thousands			3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2020
MSRs
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Fair value	$ 22,482	$ 40,254	$ 22,482
Expected life (in years)	4 years	6 years
Prepayment speed assumption (annual CPR)	21.00%	11.00%
Decrease in fair value from:
10% adverse change	$ 1,760	$ 1,643	1,760
25% adverse change	$ 4,278	$ 3,913	4,278
Discount rate assumption	13.00%	11.00%
Decrease in fair value from:
100 basis point increase	$ 611	$ 1,447	611
200 basis point increase	1,188	2,795	1,188
Senior Securities
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Fair value	$ 26,980	$ 48,765	26,980
Expected life (in years)	3 years	6 years
Prepayment speed assumption (annual CPR)	28.00%	14.00%
Decrease in fair value from:
10% adverse change	$ 2,414	$ 1,908	2,414
25% adverse change	$ 5,954	$ 5,086	5,954
Discount rate assumption	18.00%	12.00%
Decrease in fair value from:
100 basis point increase	$ 549	$ 1,079	549
200 basis point increase	$ 1,072	$ 2,482	1,072
Credit loss assumption	0.22%	0.21%
Decrease in fair value from:
10% higher losses	$ 0	$ 0	0
25% higher losses	0	0	0
Subordinate Securities
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Fair value	$ 105,347	$ 180,309	105,347
Expected life (in years)	14 years	14 years
Prepayment speed assumption (annual CPR)	15.00%	16.00%
Decrease in fair value from:
10% adverse change	$ 1,404	$ 205	1,404
25% adverse change	$ 3,836	$ 1,434	3,836
Discount rate assumption	10.00%	5.00%
Decrease in fair value from:
100 basis point increase	$ 8,088	$ 18,127	8,088
200 basis point increase	$ 15,165	$ 33,630	15,165
Credit loss assumption	0.22%	0.21%
Decrease in fair value from:
10% higher losses	$ 1,107	$ 1,804	1,107
25% higher losses	$ 2,723	$ 4,520	$ 2,723
Minimum | MSRs
Decrease in fair value from:
Impact of adverse change in prepayment speed			10.00%
Impact of increase in discount rate assumption			1.00%
Impact of adverse change in expected credit losses			10.00%
Minimum | Senior Securities
Decrease in fair value from:
Impact of adverse change in prepayment speed			10.00%
Impact of increase in discount rate assumption			1.00%
Impact of adverse change in expected credit losses			10.00%
Minimum | Subordinate Securities
Decrease in fair value from:
Impact of adverse change in prepayment speed			10.00%
Impact of increase in discount rate assumption			1.00%
Impact of adverse change in expected credit losses			10.00%
Maximum | MSRs
Decrease in fair value from:
Impact of adverse change in prepayment speed			25.00%
Impact of increase in discount rate assumption			2.00%
Impact of adverse change in expected credit losses			25.00%
Maximum | Senior Securities
Decrease in fair value from:
Impact of adverse change in prepayment speed			25.00%
Impact of increase in discount rate assumption			2.00%
Impact of adverse change in expected credit losses			25.00%
Maximum | Subordinate Securities
Decrease in fair value from:
Impact of adverse change in prepayment speed			25.00%
Impact of increase in discount rate assumption			2.00%
Impact of adverse change in expected credit losses			25.00%