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Insurance Contracts (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | $ 41 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 186 | $ 115 | $ 56 | $ 33
Liability for Claims and Claims Adjustment Expense | 893 | 805 |  |
Short Duration Insurance Contract Liability For Unpaid Clams and Allocated Claim Adjustment Expense Subtotal For Separately Presented | 22 | 0 |  |
Other adjustments (including foreign exchange) | 4 | (12) | (4) |
Commercial Auto | Operating Segments |  |  |  |
Insurance [Line Items] |  |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 85 |  |  |
Liability for Claims and Claims Adjustment Expense | 107 |  |  |
Unallocated Loss Adjustment Expense Reserve | Segment Reconciling Items |  |  |  |
Insurance [Line Items] |  |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 2 |  |  |
Liability for Claims and Claims Adjustment Expense | 6 |  |  |
Other Insurance Contracts | Segment Reconciling Items |  |  |  |
Insurance [Line Items] |  |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 69 |  |  |
Liability for Claims and Claims Adjustment Expense | 84 | 44 |  |
Specialty Property & Casualty Program |  |  |  |
Insurance [Line Items] |  |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 156 |  |  |
Specialty Property & Casualty Program | Operating Segments |  |  |  |
Insurance [Line Items] |  |  |  |
Liability for Claims and Claims Adjustment Expense | 197 |  |  |
Specialty Property & Casualty Program | Commercial Auto |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 22 |  |  |
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 28 |  |  |
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 6 |  |  |
Short-Duration Insurance Contracts, Historical Claims Duration, Year One | 9.30% |  |  |
Short-Duration Insurance Contracts, Historical Claims Duration, Year Two | 2.90% |  |  |
Short-Duration Insurance Contracts, Historical Claims Duration, Year Three | 10.70% |  |  |
Specialty Property & Casualty Program | Commercial Auto | Short-Duration Insurance Contract, Accident Year 2021 |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1 | 0 | 0 |
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 0 | 0 | 0 |
Short-Duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 0 |  |  |
Short-Duration Insurance Contract, Cumulative Number of Reported Claims | 75 |  |  |
Specialty Property & Casualty Program | Commercial Auto | Short-Duration Insurance Contract, Accident Year 2022 |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 8 | 8 |  |
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 2 | 1 |  |
Short-Duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 3 |  |  |
Short-Duration Insurance Contract, Cumulative Number of Reported Claims | 1,112 |  |  |
Specialty Property & Casualty Program | Commercial Auto | Short-Duration Insurance Contract, Accident Year 2023 |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 19 |  |  |
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 4 |  |  |
Short-Duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 10 |  |  |
Short-Duration Insurance Contract, Cumulative Number of Reported Claims | 2,531 |  |  |
Specialty Property & Casualty Program | Commercial Auto | Operating Segments |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | $ 22 |  |  |
Specialty Property & Casualty Program | Unallocated Loss Adjustment Expense Reserve | Segment Reconciling Items |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 5 |  |  |
Specialty Property & Casualty Program | Other Insurance Contracts |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 14 |  |  |
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 16 |  |  |
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 2 |  |  |
Short Duration Insurance Contract Liability For Unpaid Clams and Allocated Claim Adjustment Expense Subtotal For Separately Presented | $ 14 |  |  |
Short-Duration Insurance Contracts, Historical Claims Duration, Year One | 3.10% |  |  |
Short-Duration Insurance Contracts, Historical Claims Duration, Year Two | 0.90% |  |  |
Short-Duration Insurance Contracts, Historical Claims Duration, Year Three | 0.00% |  |  |
Specialty Property & Casualty Program | Other Insurance Contracts | Short-Duration Insurance Contract, Accident Year 2021 |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 0 | 0 | 0 |
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 0 | 0 | $ 0 |
Short-Duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 0 |  |  |
Short-Duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |
Specialty Property & Casualty Program | Other Insurance Contracts | Short-Duration Insurance Contract, Accident Year 2022 |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 0 | 0 |  |
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 0 | $ 0 |  |
Short-Duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 0 |  |  |
Short-Duration Insurance Contract, Cumulative Number of Reported Claims | 646 |  |  |
Specialty Property & Casualty Program | Other Insurance Contracts | Short-Duration Insurance Contract, Accident Year 2023 |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 16 |  |  |
Short-Duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 2 |  |  |
Short-Duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 8 |  |  |
Short-Duration Insurance Contract, Cumulative Number of Reported Claims | 11,595 |  |  |
Specialty Property & Casualty Program | Other Insurance Contracts | Segment Reconciling Items |  |  |  |
Insurance [Line Items] |  |  |  |
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | $ 14 |  |  |

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- Definition Amount of increase (decrease) in the premiums receivable on financial guarantee insurance contracts from adjustments classified as other. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 310 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c)(4)(iv) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479584/944-310-50-3 + Details
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