Loans Held for Investment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Dec. 31, 2023
Receivables [Abstract]
Commitments to purchase or sell	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Proceeds from sale of loans held-for-investment	0.0	0.0	0.0	0.0
Interest Receivable	127.3		127.3		$ 127.3	$ 129.1
Financing Receivable, Loan in Process	0.5		0.5		0.5
Financing Receivable, Excluding Accrued Interest, Modified, Subsequent Default					$ 1.3
Accrued interest reversal	$ (0.4)	$ (1.0)	$ (2.4)	$ (1.9)

Amount of writeoff of accrued interest on financing receivable recognized by reversing interest income.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-3D

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- Definition

Amortized cost excluding accrued interest, of financing receivable with payment default in current period and modified within previous 12 months preceding payment default for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 44
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-44

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- Definition

Amount of undisbursed portion of financing receivable balance. Excludes financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-3

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- Definition

Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480833/946-310-45-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

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Balance Type:	debit
Period Type:	instant

- Definition

Reflects the carrying amount of loans and leases for which agreements to acquire or dispose exist.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480981/942-825-50-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480981/942-825-50-1

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Balance Type:	credit
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- Definition

Amount of cash inflow from sale of loan held for investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-12

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- References

No definition available.

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