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Segments of Operations - Narrative (Details) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 segment | Sep. 30, 2024
Segment Reporting Information [Line Items] |  |  |  |
Number of segments | segment |  |  | 2 |
Percent of total revenue derived from sales of property and casualty insurance outside of the United States | 4.00% | 3.00% | 4.00% | 4.00%
Other |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Liability for asbestos and environmental reserves, net, period increase (decrease) | $ | $ (25) | $ (14) |  |

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- Definition Property and casualty insurance revenues derived from customers of foreign countries. + References No definition available. + Details
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- Definition The increase (decrease) during the reporting period in asbestos and environmental claims reserve, net of reinsurance recoveries. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-3 + Details
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- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 47 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482785/280-10-55-47 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 54 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482785/280-10-55-54 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-18 + Details
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