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Claim and Claim Adjustment Expense Reserves (Commercial - Net prior year claim and allocated claim adjustment expense reserve development) (Details) - Commercial - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |
Commercial | $ 11 | $ 21 | $ 11 | $ 21
General Liability | 70 | 41 | 70 | 41
Workers' Compensation | (96) | (82) | (98) | (84)
Property and Other | 2 | (2) | 2 | (2)
Total pretax (favorable) unfavorable development | $ (13) | $ (22) | $ (15) | $ (24)

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- Definition Net prior year claim and allocated claim adjustment expense reserve development, Commercial Auto + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Net prior year claim and allocated claim adjustment expense reserve development, General Liability + References No definition available. + Details
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- Definition Net prior year claim and allocated claim adjustment expense reserve development, Property and Other + References No definition available. + Details
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- Definition Net prior year claim and allocated claim adjustment expense reserve development, Workers' Compensation + References No definition available. + Details
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- Definition Pretax (favorable) unfavorable net prior year claim and allocated claim adjustment expense reserve development, excluding Life & Group + References No definition available. + Details
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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. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

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- Details
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Period Type: |