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Unpaid losses and loss expenses Unpaid Losses and loss expenses, claims development (Cumulative Net incurred Loss and Allocated Loss Adjustment Expense) (Details) $ in Millions | 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 ($) | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($) | Dec. 31, 2012 USD ($)
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Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | $ 53,940 |  |  |  |  |  |  |  |  |
North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 12,209 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 5,103 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 9,942 |  |  |  |  |  |  |  |  |
North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 36,343 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 19,119 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 18,736 |  |  |  |  |  |  |  |  |
North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 5,615 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 3,594 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 2,304 |  |  |  |  |  |  |  |  |
North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 20,704 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 17,748 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 2,963 |  |  |  |  |  |  |  |  |
North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 26,089 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 23,081 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 3,035 |  |  |  |  |  |  |  |  |
Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 13,637 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 7,028 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 7,052 |  |  |  |  |  |  |  |  |
Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 19,731 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 16,866 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 2,984 |  |  |  |  |  |  |  |  |
Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 2,806 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 1,932 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 1,191 |  |  |  |  |  |  |  |  |
Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 2,320 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 1,959 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 372 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 952 | $ 953 | $ 977 | $ 986 | $ 989 | $ 1,011 | $ 1,040 | $ 1,030 | $ 1,011 | $ 1,050
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 224 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 626 | 612 | 592 | 574 | 532 | 486 | 436 | 365 | 271 | 111
Cumulative Number of Reported Claims | 44,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,308 | 3,235 | 3,235 | 3,331 | 3,427 | 3,525 | 3,565 | 3,614 | 3,628 | 3,552
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 302 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,783 | 2,688 | 2,619 | 2,502 | 2,327 | 2,093 | 1,680 | 1,172 | 656 | 166
Cumulative Number of Reported Claims | 25,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 500 | 505 | 507 | 509 | 519 | 520 | 561 | 577 | 606 | 634
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 2 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 496 | 502 | 493 | 487 | 470 | 435 | 387 | 320 | 223 | 69
Cumulative Number of Reported Claims | 16,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,848 | 1,844 | 1,850 | 1,844 | 1,847 | 1,859 | 1,864 | 1,883 | 1,916 | 2,033
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 5 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,839 | 1,844 | 1,842 | 1,816 | 1,822 | 1,795 | 1,767 | 1,698 | 1,577 | 715
Cumulative Number of Reported Claims | 426,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2012 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,188 | 2,190 | 2,194 | 2,189 | 2,186 | 2,186 | 2,191 | 2,183 | 2,183 | 2,186
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 5 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,177 | 2,165 | 2,164 | 2,164 | 2,150 | 2,117 | 2,063 | 1,957 | 1,806 | 1,177
Cumulative Number of Reported Claims | 188,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,237 | 1,227 | 1,257 | 1,267 | 1,287 | 1,297 | 1,300 | 1,282 | 1,219 | 1,249
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 62 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,061 | 1,005 | 940 | 898 | 828 | 690 | 577 | 427 | 244 | 72
Cumulative Number of Reported Claims | 38,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,488 | 1,489 | 1,496 | 1,501 | 1,516 | 1,524 | 1,531 | 1,584 | 1,624 | 1,634
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 4 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,471 | 1,460 | 1,461 | 1,458 | 1,447 | 1,437 | 1,415 | 1,357 | 1,176 | 643
Cumulative Number of Reported Claims | 555,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 376 | 378 | 373 | 371 | 372 | 378 | 393 | 391 | 382 | 386
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 5 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 347 | 341 | 335 | 324 | 308 | 293 | 262 | 222 | 168 | 78
Short-duration Insurance Contracts, Accident Year 2012 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 184 | 183 | 185 | 185 | 188 | 190 | 192 | 201 | 211 | 232
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 179 | 179 | 180 | 180 | 177 | 172 | 166 | 156 | 130 | $ 45
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 989 | 1,014 | 1,037 | 1,073 | 1,086 | 1,127 | 1,122 | 1,108 | 1,109 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 252 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 650 | 633 | 616 | 587 | 553 | 506 | 422 | 286 | 107 |
Cumulative Number of Reported Claims | 43,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,956 | 2,964 | 3,122 | 3,216 | 3,430 | 3,533 | 3,543 | 3,542 | 3,547 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 252 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,525 | 2,465 | 2,374 | 2,232 | 2,007 | 1,597 | 1,192 | 548 | 130 |
Cumulative Number of Reported Claims | 25,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 461 | 458 | 462 | 462 | 469 | 516 | 523 | 531 | 527 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 12 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 439 | 426 | 419 | 412 | 385 | 348 | 271 | 197 | 69 |
Cumulative Number of Reported Claims | 18,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,343 | 1,344 | 1,338 | 1,340 | 1,340 | 1,360 | 1,337 | 1,424 | 1,434 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 5 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,336 | 1,335 | 1,333 | 1,324 | 1,311 | 1,285 | 1,238 | 1,138 | 651 |
Cumulative Number of Reported Claims | 455,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2013 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,949 | 1,948 | 1,945 | 1,937 | 1,925 | 1,900 | 1,897 | 1,889 | 1,860 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 23 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,916 | 1,917 | 1,895 | 1,885 | 1,843 | 1,787 | 1,688 | 1,505 | 1,043 |
Cumulative Number of Reported Claims | 132,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,124 | 1,104 | 1,137 | 1,195 | 1,228 | 1,274 | 1,230 | 1,234 | 1,238 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 73 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 938 | 917 | 866 | 799 | 699 | 557 | 412 | 258 | 82 |
Cumulative Number of Reported Claims | 39,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,527 | 1,536 | 1,545 | 1,557 | 1,584 | 1,589 | 1,635 | 1,698 | 1,703 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 12 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,503 | 1,505 | 1,502 | 1,495 | 1,477 | 1,441 | 1,410 | 1,221 | 659 |
Cumulative Number of Reported Claims | 573,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 309 | 310 | 316 | 323 | 331 | 329 | 329 | 326 | 320 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 10 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 278 | 271 | 269 | 260 | 241 | 222 | 186 | 143 | 65 |
Short-duration Insurance Contracts, Accident Year 2013 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 138 | 139 | 140 | 140 | 142 | 141 | 146 | 158 | 160 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 0 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 137 | 137 | 136 | 135 | 133 | 130 | 120 | 102 | $ 46 |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 1,037 | 1,073 | 1,100 | 1,163 | 1,215 | 1,217 | 1,201 | 1,207 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 305 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 617 | 599 | 566 | 532 | 484 | 410 | 295 | 113 |  |
Cumulative Number of Reported Claims | 45,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,198 | 3,346 | 3,470 | 3,656 | 3,718 | 3,675 | 3,586 | 3,535 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 381 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,673 | 2,584 | 2,442 | 2,202 | 1,804 | 1,250 | 679 | 164 |  |
Cumulative Number of Reported Claims | 24,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 531 | 539 | 539 | 555 | 597 | 581 | 583 | 595 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 14 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 509 | 501 | 473 | 455 | 391 | 317 | 220 | 80 |  |
Cumulative Number of Reported Claims | 17,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,552 | 1,558 | 1,550 | 1,549 | 1,559 | 1,579 | 1,661 | 1,643 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 3 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,558 | 1,554 | 1,546 | 1,532 | 1,506 | 1,484 | 1,373 | 820 |  |
Cumulative Number of Reported Claims | 483,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,141 | 2,141 | 2,147 | 2,160 | 2,146 | 2,192 | 2,206 | 2,205 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 11 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,123 | 2,116 | 2,106 | 2,080 | 2,035 | 1,926 | 1,765 | 1,310 |  |
Cumulative Number of Reported Claims | 144,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,134 | 1,125 | 1,165 | 1,248 | 1,331 | 1,316 | 1,307 | 1,237 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 101 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 890 | 847 | 784 | 701 | 588 | 457 | 283 | 107 |  |
Cumulative Number of Reported Claims | 40,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,717 | 1,723 | 1,730 | 1,740 | 1,775 | 1,785 | 1,839 | 1,774 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | (3) |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,696 | 1,689 | 1,675 | 1,662 | 1,633 | 1,571 | 1,365 | 718 |  |
Cumulative Number of Reported Claims | 548,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 330 | 329 | 346 | 343 | 342 | 339 | 333 | 332 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 11 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 295 | 286 | 276 | 264 | 248 | 217 | 184 | 91 |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 177 | 178 | 179 | 181 | 182 | 179 | 179 | 164 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 172 | 172 | 170 | 167 | 162 | 151 | 128 | $ 65 |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 1,128 | 1,154 | 1,217 | 1,279 | 1,276 | 1,259 | 1,282 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 379 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 628 | 606 | 564 | 501 | 418 | 301 | 116 |  |  |
Cumulative Number of Reported Claims | 50,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,709 | 3,736 | 3,943 | 3,977 | 3,819 | 3,709 | 3,560 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 714 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,749 | 2,533 | 2,291 | 1,856 | 1,206 | 605 | 138 |  |  |
Cumulative Number of Reported Claims | 27,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 463 | 455 | 458 | 515 | 502 | 470 | 487 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 31 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 412 | 395 | 371 | 305 | 215 | 137 | 47 |  |  |
Cumulative Number of Reported Claims | 15,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,592 | 1,589 | 1,605 | 1,638 | 1,650 | 1,745 | 1,736 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | (6) |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,587 | 1,574 | 1,572 | 1,556 | 1,488 | 1,343 | 727 |  |  |
Cumulative Number of Reported Claims | 545,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,566 | 2,570 | 2,563 | 2,544 | 2,561 | 2,550 | 2,495 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 12 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,533 | 2,508 | 2,478 | 2,392 | 2,271 | 2,084 | 1,499 |  |  |
Cumulative Number of Reported Claims | 148,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,202 | 1,219 | 1,278 | 1,301 | 1,278 | 1,249 | 1,153 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 137 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 929 | 853 | 774 | 655 | 478 | 276 | 82 |  |  |
Cumulative Number of Reported Claims | 42,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,890 | 1,908 | 1,915 | 1,933 | 1,963 | 1,985 | 1,867 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 3 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,853 | 1,836 | 1,807 | 1,786 | 1,707 | 1,481 | 811 |  |  |
Cumulative Number of Reported Claims | 570,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 308 | 304 | 308 | 300 | 299 | 288 | 284 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 14 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 266 | 249 | 232 | 217 | 191 | 158 | 90 |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 157 | 159 | 153 | 161 | 161 | 154 | 146 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 152 | 151 | 146 | 142 | 132 | 103 | $ 56 |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 1,206 | 1,269 | 1,378 | 1,383 | 1,361 | 1,367 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 439 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 621 | 584 | 529 | 452 | 326 | 122 |  |  |  |
Cumulative Number of Reported Claims | 52,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,771 | 3,799 | 3,805 | 3,692 | 3,595 | 3,534 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 773 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,596 | 2,334 | 1,975 | 1,336 | 663 | 171 |  |  |  |
Cumulative Number of Reported Claims | 27,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 480 | 481 | 524 | 527 | 502 | 504 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 51 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 398 | 375 | 324 | 246 | 145 | 52 |  |  |  |
Cumulative Number of Reported Claims | 16,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,832 | 1,818 | 1,782 | 1,800 | 1,890 | 1,911 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 34 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,786 | 1,760 | 1,733 | 1,656 | 1,505 | 846 |  |  |  |
Cumulative Number of Reported Claims | 650,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,464 | 2,471 | 2,482 | 2,545 | 2,536 | 2,440 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 27 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,398 | 2,370 | 2,314 | 2,211 | 2,052 | 1,453 |  |  |  |
Cumulative Number of Reported Claims | 154,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,382 | 1,373 | 1,385 | 1,356 | 1,289 | 1,189 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 286 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 883 | 787 | 664 | 517 | 313 | 123 |  |  |  |
Cumulative Number of Reported Claims | 43,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,972 | 1,942 | 1,938 | 1,960 | 1,973 | 1,975 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 38 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,895 | 1,886 | 1,861 | 1,791 | 1,597 | 959 |  |  |  |
Cumulative Number of Reported Claims | 581,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 243 | 243 | 234 | 235 | 226 | 223 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 16 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 192 | 175 | 159 | 142 | 113 | 57 |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 186 | 188 | 192 | 189 | 187 | 182 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 2 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 180 | 176 | 170 | 159 | 132 | $ 57 |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 1,376 | 1,393 | 1,399 | 1,380 | 1,413 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 679 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 564 | 516 | 437 | 313 | 120 |  |  |  |  |
Cumulative Number of Reported Claims | 50,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,552 | 3,631 | 3,581 | 3,499 | 3,322 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,156 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,003 | 1,701 | 1,162 | 617 | 161 |  |  |  |  |
Cumulative Number of Reported Claims | 27,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 605 | 616 | 577 | 566 | 532 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 79 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 446 | 381 | 313 | 175 | 66 |  |  |  |  |
Cumulative Number of Reported Claims | 17,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,513 | 2,521 | 2,504 | 2,608 | 2,704 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 51 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,406 | 2,392 | 2,302 | 2,087 | 979 |  |  |  |  |
Cumulative Number of Reported Claims | 763,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,998 | 2,998 | 3,002 | 3,069 | 3,035 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 63 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,870 | 2,799 | 2,668 | 2,520 | 1,698 |  |  |  |  |
Cumulative Number of Reported Claims | 163,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,343 | 1,379 | 1,330 | 1,282 | 1,180 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 205 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 842 | 676 | 516 | 310 | 94 |  |  |  |  |
Cumulative Number of Reported Claims | 44,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,149 | 2,125 | 2,143 | 2,161 | 2,122 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 15 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,052 | 2,012 | 1,938 | 1,765 | 1,000 |  |  |  |  |
Cumulative Number of Reported Claims | 589,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 218 | 217 | 219 | 215 | 213 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 17 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 155 | 140 | 122 | 100 | 46 |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 454 | 450 | 453 | 423 | 396 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 13 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 428 | 415 | 401 | 322 | $ 191 |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 1,385 | 1,379 | 1,361 | 1,359 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 681 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 528 | 451 | 329 | 130 |  |  |  |  |  |
Cumulative Number of Reported Claims | 51,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,828 | 3,697 | 3,494 | 3,375 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,445 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,777 | 1,303 | 754 | 190 |  |  |  |  |  |
Cumulative Number of Reported Claims | 28,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 580 | 575 | 564 | 536 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 110 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 365 | 270 | 169 | 74 |  |  |  |  |  |
Cumulative Number of Reported Claims | 17,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,167 | 2,175 | 2,240 | 2,053 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 41 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,074 | 2,018 | 1,825 | 1,027 |  |  |  |  |  |
Cumulative Number of Reported Claims | 903,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,118 | 3,103 | 3,037 | 3,010 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 197 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,865 | 2,706 | 2,549 | 1,926 |  |  |  |  |  |
Cumulative Number of Reported Claims | 169,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,434 | 1,392 | 1,330 | 1,279 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 493 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 627 | 485 | 322 | 109 |  |  |  |  |  |
Cumulative Number of Reported Claims | 44,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,109 | 2,132 | 2,169 | 2,083 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 29 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,936 | 1,868 | 1,668 | 954 |  |  |  |  |  |
Cumulative Number of Reported Claims | 623,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 250 | 254 | 247 | 244 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 25 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 149 | 125 | 96 | 41 |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 294 | 299 | 295 | 285 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 276 | 273 | 255 | $ 94 |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 1,401 | 1,384 | 1,391 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 718 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 467 | 341 | 143 |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 47,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,867 | 3,628 | 3,452 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,982 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,248 | 671 | 176 |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 30,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 686 | 637 | 606 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 219 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 318 | 190 | 70 |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 16,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,959 | 2,037 | 2,052 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 67 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,804 | 1,677 | 1,030 |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 1,042,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,994 | 2,993 | 2,957 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 209 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,617 | 2,437 | 1,668 |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 156,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,447 | 1,422 | 1,354 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 620 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 459 | 327 | 121 |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 42,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,049 | 2,117 | 2,098 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 22 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,849 | 1,657 | 996 |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 640,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 241 | 246 | 238 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 56 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 116 | 90 | 40 |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 133 | 137 | 139 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 18 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 99 | 84 | $ 35 |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 1,387 | 1,367 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 903 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 282 | 111 |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 31,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,832 | 4,106 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 2,780 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 590 | 152 |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 24,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 634 | 646 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 372 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 151 | 53 |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 11,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,951 | 3,148 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 357 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,271 | 1,396 |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 1,118,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,634 | 2,931 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 376 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,995 | 1,334 |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 121,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,656 | 1,740 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,101 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 283 | 105 |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 34,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,309 | 2,448 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 250 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,649 | 1,031 |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 541,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 250 | 246 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 97 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 99 | 41 |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2020 | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 255 | 211 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 34 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 178 | $ 62 |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 1,348 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,033 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 120 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 30,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 4,322 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 3,941 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 175 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 25,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 675 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 515 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 60 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 9,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,947 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,249 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,087 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 726,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 3,037 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,025 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,587 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 103,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,678 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,373 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 116 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 29,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,521 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 699 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 962 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | 531,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 281 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 196 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 35 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2021 | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 342 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 131 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 158 |  |  |  |  |  |  |  |  |
prior to 2012 | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 2,836 |  |  |  |  |  |  |  |  |
prior to 2012 | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 1,512 |  |  |  |  |  |  |  |  |
prior to 2012 | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 283 |  |  |  |  |  |  |  |  |
prior to 2012 | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 7 |  |  |  |  |  |  |  |  |
prior to 2012 | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 27 |  |  |  |  |  |  |  |  |
prior to 2012 | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 443 |  |  |  |  |  |  |  |  |
prior to 2012 | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 119 |  |  |  |  |  |  |  |  |
prior to 2012 | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 317 |  |  |  |  |  |  |  |  |
prior to 2012 | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 11 |  |  |  |  |  |  |  |  |
2012 - 2021 | North America Commercial P&C Insurance - Workers' Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 7,106 |  |  |  |  |  |  |  |  |
2012 - 2021 | North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 17,224 |  |  |  |  |  |  |  |  |
2012 - 2021 | North America Commercial P&C Insurance - Other Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 2,021 |  |  |  |  |  |  |  |  |
2012 - 2021 | North America Commercial P&C Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 2,956 |  |  |  |  |  |  |  |  |
2012 - 2021 | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 3,008 |  |  |  |  |  |  |  |  |
2012 - 2021 | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 6,609 |  |  |  |  |  |  |  |  |
2012 - 2021 | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 2,865 |  |  |  |  |  |  |  |  |
2012 - 2021 | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 874 |  |  |  |  |  |  |  |  |
2012 - 2021 | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | $ 361 |  |  |  |  |  |  |  |  |

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