Residential Loans - Characteristics of Loans Held-for-Investment (Details) $ in Thousands			12 Months Ended
Dec. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan	Dec. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of Loans \| loan			198	669
Principal amount outstanding on loans securitized	$ 172,748	$ 524,928	$ 172,748	$ 524,928
Residential loans, held-for-investment \| Legacy Sequoia
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of Loans \| loan	1,908	2,198
Principal amount outstanding on loans securitized	$ 333,474	$ 424,829	333,474	424,829
Loans, at fair value	$ 285,935	$ 407,890	$ 285,935	$ 407,890
Number of loans in foreclosure \| loan	21	16	21	16
Loans held as assets amount in foreclosure	$ 4,939	$ 3,673	$ 4,939	$ 3,673
Residential loans, held-for-investment \| Sequoia Choice
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of Loans \| loan	2,177	3,156
Principal amount outstanding on loans securitized	$ 1,550,454	$ 2,240,679	1,550,454	2,240,679
Loans, at fair value	$ 1,565,322	$ 2,291,463	$ 1,565,322	$ 2,291,463
Number of loans in foreclosure \| loan	3	3	3	3
Loans held as assets amount in foreclosure	$ 2,251	$ 2,290	$ 2,251	$ 2,290
Residential loans, held-for-investment \| Freddie Mac SLST
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of Loans \| loan	13,605	14,502
Principal amount outstanding on loans securitized	$ 2,247,771	$ 2,428,035	2,247,771	2,428,035
Loans, at fair value	$ 2,221,153	$ 2,367,215	$ 2,221,153	$ 2,367,215
Number of loans in foreclosure \| loan	245	208	245	208
Loans held as assets amount in foreclosure	$ 38,610	$ 33,042	$ 38,610	$ 33,042
Residential loans, held-for-investment \| Financing Receivables, Equal to Greater than 90 Days Past Due \| Legacy Sequoia
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans past due \| loan	52	39	52	39
Loans held as assets, 90 days or more past due	$ 17,285	$ 9,803	$ 17,285	$ 9,803
Residential loans, held-for-investment \| Financing Receivables, Equal to Greater than 90 Days Past Due \| Sequoia Choice
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans past due \| loan	94	9	94	9
Loans held as assets, 90 days or more past due	$ 74,742	$ 6,755	$ 74,742	$ 6,755
Residential loans, held-for-investment \| Financing Receivables, Equal to Greater than 90 Days Past Due \| Freddie Mac SLST
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans past due \| loan	2,110	587	2,110	587
Loans held as assets, 90 days or more past due	$ 389,245	$ 134,680	$ 389,245	$ 134,680
Residential loans, held-for-investment \| Redwood
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of Loans \| loan	0	2,940
Principal amount outstanding on loans securitized	$ 0	$ 2,052,778	0	2,052,778
Loans, at fair value	$ 0	$ 2,111,897	$ 0	$ 2,111,897
Number of loans in foreclosure \| loan	0	0	0	0
Loans held as assets amount in foreclosure	$ 0	$ 0	$ 0	$ 0
Residential loans, held-for-investment \| Redwood \| Financing Receivables, Equal to Greater than 90 Days Past Due
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal amount outstanding on loans securitized	$ 0	$ 1,424	$ 0	$ 1,424
Number of loans past due \| loan	0	2	0	2
Loans held as assets, 90 days or more past due	$ 0	$ 1,585	$ 0	$ 1,585

Fair Value, Option, Loans Held As Assets, Aggregate Amount In Foreclosure

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Financing Receivable, Number Of Loans In Foreclosure

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Number of mortgage loans within investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Footnote 3
-Subsection 29

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Footnote 3))
-URI http://asc.fasb.org/extlink&oid=120402547&loc=d3e617274-123014

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This item represents the aggregate fair value of loans held as assets that are 90 days or more past due for which the fair value option has been elected.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

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Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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-Topic 310
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-Section 45
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This is the sum of principal amount outstanding for both securitized and unsecuritized loans of all types.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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