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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Reference 3: 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

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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 Property (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 Property Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	3,589
Cumulative paid losses and ALAE, net of reinsurance	3,134
All outstanding liabilities before, net of reinsurance	14
Liabilities for loss and ALAE, net of reinsurance	469
2020 \| Commercial Property Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	713	$ 716	$ 719	$ 742	$ 855
Total of incurred but not reported liabilities plus expected development on reported losses	$ 18
Cumulative number of reported claims \| reported_claim	24
Cumulative paid losses and ALAE, net of reinsurance	$ 695	687	672	637	$ 489
2021 \| Commercial Property Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	575	576	586	607
Total of incurred but not reported liabilities plus expected development on reported losses	$ 6
Cumulative number of reported claims \| reported_claim	14
Cumulative paid losses and ALAE, net of reinsurance	$ 564	558	527	$ 326
2022 \| Commercial Property Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	752	779	813
Total of incurred but not reported liabilities plus expected development on reported losses	$ 9
Cumulative number of reported claims \| reported_claim	16
Cumulative paid losses and ALAE, net of reinsurance	$ 727	691	$ 393
2023 \| Commercial Property Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	786	833
Total of incurred but not reported liabilities plus expected development on reported losses	$ 14
Cumulative number of reported claims \| reported_claim	14
Cumulative paid losses and ALAE, net of reinsurance	$ 719	$ 506
2024 \| Commercial Property Line \| Commercial Insurance
Claims Development
Incurred losses and ALAE, net of reinsurance for the years ended December 31,	763
Total of incurred but not reported liabilities plus expected development on reported losses	$ 182
Cumulative number of reported claims \| reported_claim	11
Cumulative paid losses and ALAE, net of reinsurance	$ 429