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			12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
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	$ 40,254	$ 58,572	$ 40,254	$ 58,572
Expected life (in years)	6 years	8 years
Prepayment speed assumption (annual CPR)	11.00%	7.00%
Decrease in fair value from:
10% adverse change	$ 1,643	$ 1,668	1,643	1,668
25% adverse change	$ 3,913	$ 4,027	$ 3,913	$ 4,027
Discount rate assumption	11.00%	11.00%
Impact of adverse change in prepayment speed			25.00%	25.00%
Decrease in fair value from:
100 basis point increase	$ 1,447	$ 2,323	$ 1,447	$ 2,323
200 basis point increase	2,795	4,493	$ 2,795	$ 4,493
Impact of increase in discount rate assumption			1.00%	1.00%
Decrease in fair value from:
Impact of adverse change in expected credit losses			25.00%	25.00%
Senior IO 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	$ 48,765	$ 61,178	$ 48,765	$ 61,178
Expected life (in years)	6 years	7 years
Prepayment speed assumption (annual CPR)	14.00%	10.00%
Decrease in fair value from:
10% adverse change	$ 1,908	$ 2,151	1,908	2,151
25% adverse change	$ 5,086	$ 5,127	$ 5,086	$ 5,127
Discount rate assumption	12.00%	12.00%
Impact of adverse change in prepayment speed			25.00%	25.00%
Decrease in fair value from:
100 basis point increase	$ 1,079	$ 2,190	$ 1,079	$ 2,190
200 basis point increase	$ 2,482	$ 4,226	$ 2,482	$ 4,226
Credit loss assumption	0.21%	0.20%
Impact of increase in discount rate assumption			1.00%	1.00%
Decrease in fair value from:
10% higher losses	$ 0	$ 0	$ 0	$ 0
25% higher losses	0	0	$ 0	$ 0
Impact of adverse change in expected credit losses			25.00%	25.00%
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	$ 180,309	$ 230,247	$ 180,309	$ 230,247
Expected life (in years)	14 years	15 years
Prepayment speed assumption (annual CPR)	16.00%	9.00%
Decrease in fair value from:
10% adverse change	$ 205	$ 201	205	201
25% adverse change	$ 1,434	$ 1,372	$ 1,434	$ 1,372
Discount rate assumption	5.00%	6.00%
Impact of adverse change in prepayment speed			25.00%	25.00%
Decrease in fair value from:
100 basis point increase	$ 18,127	$ 21,982	$ 18,127	$ 21,982
200 basis point increase	$ 33,630	$ 40,641	$ 33,630	$ 40,641
Credit loss assumption	0.21%	0.20%
Impact of increase in discount rate assumption			1.00%	1.00%
Decrease in fair value from:
10% higher losses	$ 1,804	$ 1,387	$ 1,804	$ 1,387
25% higher losses	$ 4,520	$ 3,471	$ 4,520	$ 3,471
Impact of adverse change in expected credit losses			25.00%	25.00%