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.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Amount, after reinsurance, of paid claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

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- Definition

Undiscounted amount, after reinsurance, of incurred-but-not-reported (IBNR) liabilities plus expected development on reported claims, for claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

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- Definition

Undiscounted amount, after reinsurance, of incurred claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

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- Definition

Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

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- Definition

Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts for accident years not separately presented in claim development information. Excludes unallocated claim adjustment expense.

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- Definition

Cumulative number of reported claims for short-duration insurance contracts.

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Property Casualty Loss and Loss Expense - Claims Development - Commercial Auto (Details) reported_claim in Thousands, $ in Millions	Dec. 31, 2024 USD ($) reported_claim	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	$ 3,589
Liabilities for loss and ALAE, net of reinsurance	9,416
Commercial Auto Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	2,514
Cumulative paid losses and ALAE, net of reinsurance	1,683
All outstanding liabilities before, net of reinsurance	40
Liabilities for loss and ALAE, net of reinsurance	871
2020 \| Commercial Auto Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	382	$ 377	$ 384	$ 391	$ 424
Total of incurred but not reported liabilities plus expected development on reported losses	$ 7
Cumulative number of reported claims \| reported_claim	36
Cumulative paid losses and ALAE, net of reinsurance	$ 357	328	280	214	$ 154
2021 \| Commercial Auto Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	463	465	477	470
Total of incurred but not reported liabilities plus expected development on reported losses	$ 23
Cumulative number of reported claims \| reported_claim	39
Cumulative paid losses and ALAE, net of reinsurance	$ 398	346	278	$ 179
2022 \| Commercial Auto Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	560	569	558
Total of incurred but not reported liabilities plus expected development on reported losses	$ 60
Cumulative number of reported claims \| reported_claim	41
Cumulative paid losses and ALAE, net of reinsurance	$ 410	332	$ 217
2023 \| Commercial Auto Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	544	550
Total of incurred but not reported liabilities plus expected development on reported losses	$ 98
Cumulative number of reported claims \| reported_claim	37
Cumulative paid losses and ALAE, net of reinsurance	$ 322	$ 216
2024 \| Commercial Auto Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	565
Total of incurred but not reported liabilities plus expected development on reported losses	$ 252
Cumulative number of reported claims \| reported_claim	31
Cumulative paid losses and ALAE, net of reinsurance	$ 196