Insurance Regulatory Restrictions Additional Details (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Average Annual Rate Of Return	5.86%	3.22%
Prescribed Discount Rate Percentage	5.10%
Minimum [Member]
Settlement Agreement Annual Restricted Payment Amount	$ 5.0
Maximum [Member]
Settlement Agreement Annual Restricted Payment Amount	7.5
Ambac Assurance [Member]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	897.0	$ 598.0
Ambac Assurance [Member] \| Prescribed Or Permitted Additional Accounting Practices [Member]
Statutory Accounting Practices, Prescribed Practice, Amount	(24.0)	90.0
Everspan Indemnity
Statutory Accounting Practices, Statutory Capital and Surplus, Balance	$ 108.0	$ 107.0

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- Definition

Discount rate percentage for the purpose of discounting statutory loss reserves and estimated impairment losses on subsidiary guarantees prescribed the regulator.

+ References

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- Definition

Settlement Agreement Annual Restricted Payment Amount

+ References

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- Definition

Amount as of the balance sheet date of each item listed to reconcile the differences resulting from applying state prescribed statutory accounting practices rather than statutory accounting practices prescribed by National Association of Insurance Commissioners.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 944
-SubTopic 505
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479989/944-505-50-3

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- Definition

The amount of statutory capital and surplus (stockholders' equity) as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

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-Name Accounting Standards Codification
-Topic 944
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479989/944-505-50-1

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