Goodwill and Other Intangibles - Narrative (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Dec. 31, 2025 |
|
| Intangible Asset, Goodwill and Other [Abstract] | ||||
| Changes in the goodwill | $ 0 | |||
| Goodwill | $ 327,000,000 | 327,000,000 | $ 327,000,000 | |
| Amortizable intangible assets related to property and casualty insurance acquisitions | 174,000,000 | 174,000,000 | 189,000,000 | |
| Accumulated amortization | 90,000,000 | 90,000,000 | $ 75,000,000 | |
| Amortization of intangible assets | $ 5,000,000 | $ 15,000,000 | ||
| Intangible Asset, Finite-Lived, Impairment Loss | $ 2,000,000 | |||
| X | ||||||||||
- Definition Amount of amortization expense for finite-lived intangible asset. Excludes goodwill and capitalized cost for software to be sold, leased, or marketed. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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| X | ||||||||||
- Definition Amount of accumulated amortization of finite-lived intangible asset. Excludes goodwill and capitalized cost for software to be sold, leased, or marketed. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- Definition Amount, after accumulated amortization, of finite-lived intangible asset. Excludes goodwill and capitalized cost for software to be sold, leased, or marketed. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- Definition Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of increase (decrease) of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- Definition Amount of impairment loss for finite-lived intangible asset. Excludes goodwill and capitalized cost for software to be sold, leased, or marketed. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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