Long-Term Debt - Summary of Financial Information Relating to Note Payable Secured by Credit Risk Transfer and Mortgage Servicing Assets (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Short Term Debt [Line Items]
Amortization of premiums and debt issuance costs	$ 4,832	$ 3,919
Notes Payable [Member] \| Freddie Mac MSR Financing
Short Term Debt [Line Items]
Amortization of premiums and debt issuance costs	$ 1,800	$ 2,300

Amount of amortization expense attributable to debt discount (premium) and debt issuance costs.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 69E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69E

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 470
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147481568/470-20-55-69F

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1F

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org/1943274/2147482925/835-30-45-3

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