Prior Year Claims and Claims Adjustment Expense, Percentage

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- 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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- Definition

Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred and costs incurred in the claim settlement process.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
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Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs.

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Reserve for Property and Casualty Insurance Claims and Claims Expense - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Increase (decrease) in claims and claims expense
Prior years	$ (753)	$ (424)	$ (2,398)	$ (1,045)
Personal auto injury coverage \| Favorable Severity Development
Increase (decrease) in claims and claims expense
Prior years	$ 802		$ 2,070
Personal auto injury coverage \| Favorable Severity Development \| Short-Duration Insurance Contract, Accident Year 2025
Increase (decrease) in claims and claims expense
Percentage of claims	28.00%		29.00%
Personal auto injury coverage \| Favorable Severity Development \| Short-Duration Insurance Contract, Accident Year 2023 And 2024
Increase (decrease) in claims and claims expense
Percentage of claims	55.00%		52.00%
Personal other auto coverages \| Favorable Severity Development
Increase (decrease) in claims and claims expense
Prior years	$ 74		$ 279
Catastrophe
Increase (decrease) in claims and claims expense
Losses from catastrophes, net of recoveries			4,610	4,750
Prior years	$ 10	$ (28)	$ 73	$ (38)