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, 2023 USD ($) loan	Dec. 31, 2022 USD ($) loan
Legacy Sequoia
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans \| loan	1,222	1,304
Unpaid principal balance	$ 189,757	$ 204,404
Fair value of loans	$ 170,000	$ 184,932
Weighted average coupon (as a percent)	5.57%	4.51%
Number of loans in foreclosure \| loan	10	11
Unpaid principal balance of loans in foreclosure	$ 2,336	$ 1,166
Sequoia
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans \| loan	5,287	4,624
Unpaid principal balance	$ 4,449,021	$ 3,847,091
Fair value of loans	$ 3,831,538	$ 3,190,417
Weighted average coupon (as a percent)	3.56%	3.25%
Number of loans in foreclosure \| loan	3	5
Unpaid principal balance of loans in foreclosure	$ 2,308	$ 4,654
Freddie Mac SLST
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of loans \| loan	10,748	10,882
Unpaid principal balance	$ 1,695,479	$ 1,719,236
Fair value of loans	$ 1,464,345	$ 1,457,058
Weighted average coupon (as a percent)	4.50%	4.50%
Number of loans in foreclosure \| loan	418	427
Unpaid principal balance of loans in foreclosure	$ 74,676	$ 72,440
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	26	30
Fair value of loans with 90+ day delinquencies	$ 5,856	$ 6,824
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	7	10
Fair value of loans with 90+ day delinquencies	$ 5,147	$ 7,799
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	1,033	1,211
Fair value of loans with 90+ day delinquencies	$ 174,559	$ 209,397

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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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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 https://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 https://asc.fasb.org/extlink&oid=123596393&loc=d3e14064-108612

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- Definition

Amortized cost, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

+ 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 https://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

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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 https://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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