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Claim and Claim Adjustment Expense Reserves (International - Excluding Hardy - Net Incurred Claims and Allocated Claim Adjustment Expenses) (Details) - Excluding Hardy - International $ in Millions | Dec. 31, 2024 USD ($) claim | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
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Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 3,701 |  |  |  |  |  |  |  |  |
IBNR | 1,170 |  |  |  |  |  |  |  |  |
2015 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | 266 | $ 267 | $ 271 | $ 272 | $ 270 | $ 267 | $ 272 | $ 288 | $ 289 | $ 275
IBNR | $ 10 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 22,957 |  |  |  |  |  |  |  |  |
2016 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 289 | 293 | 277 | 275 | 262 | 271 | 273 | 287 | $ 269 |
IBNR | $ 24 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 15,731 |  |  |  |  |  |  |  |  |
2017 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 385 | 377 | 344 | 356 | 360 | 367 | 346 | $ 285 |  |
IBNR | $ 44 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 16,571 |  |  |  |  |  |  |  |  |
2018 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 397 | 390 | 380 | 368 | 369 | 364 | $ 347 |  |  |
IBNR | $ 38 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 21,371 |  |  |  |  |  |  |  |  |
2019 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 347 | 343 | 340 | 333 | 337 | $ 324 |  |  |  |
IBNR | $ 57 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 19,122 |  |  |  |  |  |  |  |  |
2020 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 328 | 328 | 343 | 352 | $ 360 |  |  |  |  |
IBNR | $ 81 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 15,920 |  |  |  |  |  |  |  |  |
2021 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 347 | 355 | 375 | $ 386 |  |  |  |  |  |
IBNR | $ 121 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 15,665 |  |  |  |  |  |  |  |  |
2022 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 409 | 416 | $ 406 |  |  |  |  |  |  |
IBNR | $ 178 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 13,324 |  |  |  |  |  |  |  |  |
2023 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 452 | $ 454 |  |  |  |  |  |  |  |
IBNR | $ 266 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 11,289 |  |  |  |  |  |  |  |  |
2024 |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Net Incurred Claim and Claim Adjustment Expenses [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred claims and allocated claim adjustment expense, net | $ 481 |  |  |  |  |  |  |  |  |
IBNR | $ 351 |  |  |  |  |  |  |  |  |
Cumulative Number of Claims | claim | 8,017 |  |  |  |  |  |  |  |  |

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