Business Purpose Loans - Classifications and Carrying Values of Business Purpose Residential Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Residential Bridge, Held-for-sale at fair value
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	$ 0	$ 0
Bridge loans held-for-investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	641,765	745,006
Bridge loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	641,765	745,006
Held-for-sale at fair value, Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	245,394	331,565
Held-for-investment at fair value, Total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	3,890,959	3,175,178
Business Purpose Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	4,136,353	3,506,743
Redwood | Single-family rental loans, held-for-sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	245,394	331,565
Redwood | Single-family rental loans held-for-investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	0	237,620
Redwood | Single-family rental loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	245,394	569,185
CoreVest LLC | Single-family rental loans, held-for-sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	0	0
CoreVest LLC | Single-family rental loans held-for-investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	3,249,194	2,192,552
CoreVest LLC | Single-family rental loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at fair value	$ 3,249,194	$ 2,192,552