Residential Loans - Characteristics of Loans Held-for-Investment (Details) - Held-for-investment at fair value $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2022 USD ($) loan	Dec. 31, 2021 USD ($) loan
Legacy Sequoia
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans \| loan	1,524	1,583
Unpaid principal balance	$ 248,814	$ 264,057
Fair value of loans	$ 222,213	$ 230,455
Weighted average coupon (as a percent)	1.88%	1.87%
Number of loans in foreclosure \| loan	10	10
Unpaid principal balance of loans in foreclosure	$ 902	$ 2,188
Sequoia
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans \| loan	4,870	4,300
Unpaid principal balance	$ 4,123,176	$ 3,605,469
Fair value of loans	$ 3,872,316	$ 3,628,465
Weighted average coupon (as a percent)	3.28%	3.39%
Number of loans in foreclosure \| loan	2	2
Unpaid principal balance of loans in foreclosure	$ 1,484	$ 1,624
Freddie Mac SLST
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans \| loan	11,654	11,986
Unpaid principal balance	$ 1,865,735	$ 1,932,241
Fair value of loans	$ 1,775,538	$ 1,888,230
Weighted average coupon (as a percent)	4.52%	4.51%
Number of loans in foreclosure \| loan	256	241
Unpaid principal balance of loans in foreclosure	$ 43,467	$ 43,637
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 with 90+ day delinquencies \| loan	34	32
Fair value of loans with 90+ day delinquencies	$ 6,996	$ 7,482
Financing Receivables, Equal to Greater than 90 Days Past Due \| Sequoia
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans with 90+ day delinquencies \| loan	16	18
Fair value of loans with 90+ day delinquencies	$ 12,879	$ 15,124
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 with 90+ day delinquencies \| loan	1,291	1,208
Fair value of loans with 90+ day delinquencies	$ 220,402	$ 212,961

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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Financing Receivable, Number Of Loans Past Due

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Loans Held-for-Investment, Weighted Average Coupon Rate

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

+ References

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)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447

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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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
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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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