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			6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2020	Dec. 31, 2019
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	$ 18,727	$ 40,254	$ 18,727	$ 40,254
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	$ 1,477	$ 1,643	1,477	1,643
25% adverse change	$ 3,435	$ 3,913	3,435	3,913
Discount rate assumption	12.00%	11.00%
Decrease in fair value from:
100 basis point increase	$ 548	$ 1,447	548	1,447
200 basis point increase	1,061	2,795	1,061	2,795
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	$ 21,524	$ 48,765	21,524	48,765
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	$ 1,855	$ 1,908	1,855	1,908
25% adverse change	$ 4,489	$ 5,086	4,489	5,086
Discount rate assumption	14.00%	12.00%
Decrease in fair value from:
100 basis point increase	$ 196	$ 1,079	196	1,079
200 basis point increase	$ 652	$ 2,482	652	2,482
Credit loss assumption	0.22%	0.21%
Decrease in fair value from:
10% higher losses	$ 0	$ 0	0	0
25% higher losses	0	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	$ 121,189	$ 180,309	121,189	180,309
Expected life (in years)	12 years	14 years
Prepayment speed assumption (annual CPR)	24.00%	16.00%
Decrease in fair value from:
10% adverse change	$ 1,361	$ 205	1,361	205
25% adverse change	$ 4,246	$ 1,434	4,246	1,434
Discount rate assumption	6.00%	5.00%
Decrease in fair value from:
100 basis point increase	$ 10,543	$ 18,127	10,543	18,127
200 basis point increase	$ 19,824	$ 33,630	19,824	33,630
Credit loss assumption	0.22%	0.21%
Decrease in fair value from:
10% higher losses	$ 1,888	$ 1,804	1,888	1,804
25% higher losses	$ 4,706	$ 4,520	$ 4,706	$ 4,520
Minimum | MSRs
Decrease in fair value from:
Impact of adverse change in prepayment speed			10.00%	10.00%
Impact of increase in discount rate assumption			1.00%	1.00%
Impact of adverse change in expected credit losses			10.00%	10.00%
Minimum | Senior Securities
Decrease in fair value from:
Impact of adverse change in prepayment speed			10.00%	10.00%
Impact of increase in discount rate assumption			1.00%	1.00%
Impact of adverse change in expected credit losses			10.00%	10.00%
Minimum | Subordinate Securities
Decrease in fair value from:
Impact of adverse change in prepayment speed			10.00%	10.00%
Impact of increase in discount rate assumption			1.00%	1.00%
Impact of adverse change in expected credit losses			10.00%	10.00%
Maximum | MSRs
Decrease in fair value from:
Impact of adverse change in prepayment speed			25.00%	25.00%
Impact of increase in discount rate assumption			2.00%	2.00%
Impact of adverse change in expected credit losses			25.00%	25.00%
Maximum | Senior Securities
Decrease in fair value from:
Impact of adverse change in prepayment speed			25.00%	25.00%
Impact of increase in discount rate assumption			2.00%	2.00%
Impact of adverse change in expected credit losses			25.00%	25.00%
Maximum | Subordinate Securities
Decrease in fair value from:
Impact of adverse change in prepayment speed			25.00%	25.00%
Impact of increase in discount rate assumption			2.00%	2.00%
Impact of adverse change in expected credit losses			25.00%	25.00%