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+ Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Goodwill by segment
Goodwill	$ 4,060	$ 4,066
Reportable Segments [Member] \| Business Insurance [Member]
Goodwill by segment
Goodwill	2,551
Reportable Segments [Member] \| Bond & Specialty Insurance [Member]
Goodwill by segment
Goodwill	837
Reportable Segments [Member] \| Personal Insurance [Member]
Goodwill by segment
Goodwill	646
Other [Member]
Goodwill by segment
Goodwill	$ 26
Before Reclassifications of Held For Sale [Member] \| Reportable Segments [Member] \| Business Insurance [Member]
Goodwill by segment
Goodwill		2,601
Before Reclassifications of Held For Sale [Member] \| Reportable Segments [Member] \| Bond & Specialty Insurance [Member]
Goodwill by segment
Goodwill		838
Before Reclassifications of Held For Sale [Member] \| Reportable Segments [Member] \| Personal Insurance [Member]
Goodwill by segment
Goodwill		809
Before Reclassifications of Held For Sale [Member] \| Other [Member]
Goodwill by segment
Goodwill		26
Held for Sale Reclassification [Member]
Goodwill by segment
Goodwill		$ (208)