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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) number in Thousands, $ in Millions | 12 Months Ended |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
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 ($) | Dec. 31, 2011 USD ($) | Dec. 31, 2010 USD ($) | Dec. 31, 2009 USD ($)
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | $ 45,847 |  |  |  |  |  |  |  |  |
PPD adjustments | 63 |  |  |  |  |  |  |  |  |
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 | 11,613 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 5,004 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 2,574 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 9,183 |  |  |  |  |  |  |  |  |
North America Commercial P&C Insurance - Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 34,078 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 19,079 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 1,486 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 16,485 |  |  |  |  |  |  |  |  |
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 | 5,109 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 3,512 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 287 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 1,884 |  |  |  |  |  |  |  |  |
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 | 17,206 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 15,357 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 22 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 1,871 |  |  |  |  |  |  |  |  |
North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 22,911 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 20,610 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 18 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 2,319 |  |  |  |  |  |  |  |  |
North America Personal P&C Insurance [Member] | Catastrophe [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Period Increase (Decrease) | 200 |  |  |  |  |  |  |  |  |
Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 12,201 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 6,751 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 383 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 5,833 |  |  |  |  |  |  |  |  |
Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 18,107 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 15,890 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 48 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 2,265 |  |  |  |  |  |  |  |  |
Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 3,103 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 2,236 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 351 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 1,218 |  |  |  |  |  |  |  |  |
Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | 2,176 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 1,799 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net, Not Separately Presented | 13 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 390 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [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 | 964 | $ 965 | $ 972 | $ 966 | $ 977 | $ 980 | $ 990 | $ 997 | $ 998 | $ 1,029
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 218 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 633 | 617 | 597 | 550 | 519 | 475 | 416 | 348 | 258 | 107
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 282 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [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 | $ 3,082 | 3,096 | 3,237 | 3,309 | 3,386 | 3,636 | 3,737 | 3,764 | 3,777 | 3,791
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 221 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,766 | 2,725 | 2,673 | 2,541 | 2,354 | 2,017 | 1,670 | 1,159 | 587 | 134
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 20 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [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 | $ 452 | 445 | 450 | 452 | 458 | 492 | 535 | 555 | 589 | 599
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 | $ 431 | 427 | 422 | 413 | 401 | 373 | 336 | 287 | 206 | 70
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 15 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [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 | $ 1,183 | 1,185 | 1,186 | 1,189 | 1,189 | 1,196 | 1,213 | 1,243 | 1,298 | 1,302
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 | $ 1,178 | 1,178 | 1,178 | 1,176 | 1,168 | 1,160 | 1,146 | 1,122 | 1,032 | 618
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,124 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,527 | 1,529 | 1,530 | 1,534 | 1,534 | 1,541 | 1,549 | 1,563 | 1,593 | 1,606
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 | $ 1,520 | 1,519 | 1,517 | 1,509 | 1,499 | 1,482 | 1,435 | 1,343 | 1,233 | 884
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 125 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,138 | 1,152 | 1,204 | 1,205 | 1,309 | 1,422 | 1,421 | 1,414 | 1,367 | 1,231
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 | $ 1,007 | 978 | 952 | 861 | 791 | 733 | 641 | 502 | 327 | 117
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 38 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,303 | 1,301 | 1,302 | 1,313 | 1,313 | 1,331 | 1,350 | 1,380 | 1,464 | 1,492
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 | $ 1,287 | 1,283 | 1,284 | 1,281 | 1,275 | 1,265 | 1,241 | 1,177 | 1,043 | 572
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 516 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 303 | 313 | 318 | 328 | 344 | 363 | 367 | 360 | 348 | 316
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 | $ 262 | 255 | 239 | 226 | 208 | 187 | 154 | 116 | 79 | 34
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2009 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 137 | 138 | 138 | 138 | 140 | 142 | 149 | 150 | 170 | 139
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 | $ 133 | 133 | 133 | 133 | 132 | 130 | 128 | 121 | 105 | $ 52
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [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 | $ 1,018 | 1,020 | 1,028 | 1,052 | 1,064 | 1,065 | 1,050 | 1,037 | 1,049 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 248 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 666 | 641 | 617 | 592 | 551 | 493 | 411 | 300 | 123 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 303 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [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 | $ 2,991 | 3,103 | 3,123 | 3,245 | 3,413 | 3,554 | 3,594 | 3,576 | 3,571 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 234 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,658 | 2,523 | 2,423 | 2,257 | 1,891 | 1,557 | 1,107 | 611 | 126 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 19 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [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 | $ 483 | 492 | 480 | 478 | 506 | 545 | 600 | 607 | 613 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 8 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 452 | 448 | 443 | 433 | 392 | 363 | 321 | 236 | 97 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 15 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [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 | $ 1,393 | 1,403 | 1,409 | 1,413 | 1,421 | 1,423 | 1,459 | 1,535 | 1,500 |
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 | $ 1,390 | 1,393 | 1,393 | 1,389 | 1,381 | 1,356 | 1,319 | 1,221 | 722 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,058 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,820 | 1,819 | 1,821 | 1,827 | 1,830 | 1,834 | 1,852 | 1,875 | 1,866 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 8 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,809 | 1,807 | 1,801 | 1,790 | 1,768 | 1,726 | 1,667 | 1,519 | 1,151 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 149 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,139 | 1,134 | 1,138 | 1,260 | 1,312 | 1,375 | 1,304 | 1,259 | 1,180 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 83 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 942 | 899 | 847 | 797 | 709 | 603 | 461 | 264 | 102 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 40 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,575 | 1,573 | 1,590 | 1,603 | 1,617 | 1,623 | 1,635 | 1,660 | 1,638 |
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 | $ 1,541 | 1,535 | 1,534 | 1,528 | 1,515 | 1,477 | 1,415 | 1,218 | 664 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 560 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 386 | 399 | 413 | 423 | 429 | 440 | 429 | 418 | 398 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 39 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 314 | 306 | 291 | 273 | 249 | 220 | 179 | 124 | 56 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2010 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 222 | 223 | 222 | 221 | 219 | 215 | 221 | 232 | 197 |
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 | $ 214 | 214 | 211 | 213 | 203 | 197 | 186 | 160 | $ 56 |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [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 | $ 1,008 | 1,012 | 1,022 | 1,053 | 1,049 | 1,046 | 1,030 | 1,037 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 271 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 616 | 595 | 567 | 533 | 484 | 411 | 294 | 119 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 286 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [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 | $ 3,309 | 3,377 | 3,492 | 3,588 | 3,658 | 3,623 | 3,579 | 3,494 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 473 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,736 | 2,655 | 2,473 | 2,211 | 1,802 | 1,207 | 651 | 160 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 20 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [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 | $ 510 | 516 | 524 | 532 | 548 | 580 | 589 | 580 |  |
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 | $ 479 | 465 | 460 | 436 | 400 | 341 | 235 | 86 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 16 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [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 | $ 1,831 | 1,831 | 1,835 | 1,831 | 1,852 | 1,873 | 1,930 | 1,956 |  |
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 | $ 1,817 | 1,812 | 1,807 | 1,783 | 1,773 | 1,714 | 1,570 | 938 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,052 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [Member] | North America Personal P&C Insurance [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 2,154 | 2,155 | 2,156 | 2,160 | 2,169 | 2,181 | 2,205 | 2,203 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 9 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,141 | 2,134 | 2,125 | 2,101 | 2,048 | 1,968 | 1,831 | 1,357 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 168 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Overseas General Insurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 988 | 1,038 | 1,052 | 1,116 | 1,199 | 1,209 | 1,216 | 1,210 |  |
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 | $ 811 | 760 | 688 | 610 | 511 | 382 | 239 | 87 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 41 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Overseas General Insurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 1,808 | 1,818 | 1,826 | 1,838 | 1,855 | 1,894 | 1,951 | 1,861 |  |
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 | $ 1,766 | 1,762 | 1,754 | 1,739 | 1,709 | 1,654 | 1,453 | 753 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 578 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Global Reinsurance - Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 406 | 412 | 416 | 425 | 430 | 426 | 411 | 404 |  |
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 | $ 323 | 310 | 290 | 266 | 235 | 195 | 145 | 70 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2011 [Member] | Global Reinsurance - Non-Casualty [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net | $ 261 | 261 | 262 | 261 | 260 | 270 | 272 | 271 |  |
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 | $ 257 | 255 | 253 | 248 | 230 | 205 | 174 | $ 85 |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 986 | 989 | 1,011 | 1,040 | 1,030 | 1,011 | 1,050 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 292 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 574 | 532 | 486 | 436 | 365 | 271 | 111 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 287 |  |  |  |  |  |  |  |  |
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 | $ 3,323 | 3,419 | 3,517 | 3,557 | 3,606 | 3,622 | 3,546 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 626 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,497 | 2,322 | 2,089 | 1,677 | 1,170 | 654 | 166 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 20 |  |  |  |  |  |  |  |  |
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 | $ 508 | 518 | 519 | 560 | 576 | 605 | 633 |  |  |
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 | $ 486 | 470 | 435 | 386 | 319 | 222 | 69 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 16 |  |  |  |  |  |  |  |  |
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 | $ 1,840 | 1,842 | 1,854 | 1,860 | 1,878 | 1,911 | 2,029 |  |  |
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 | $ 1,812 | 1,817 | 1,790 | 1,762 | 1,694 | 1,573 | 713 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,036 |  |  |  |  |  |  |  |  |
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 | $ 2,185 | 2,182 | 2,182 | 2,187 | 2,179 | 2,179 | 2,181 |  |  |
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 | $ 2,160 | 2,146 | 2,113 | 2,059 | 1,954 | 1,803 | 1,174 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 173 |  |  |  |  |  |  |  |  |
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 | $ 1,258 | 1,278 | 1,297 | 1,301 | 1,283 | 1,220 | 1,252 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 166 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 888 | 818 | 683 | 572 | 424 | 244 | 73 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 43 |  |  |  |  |  |  |  |  |
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 | $ 1,557 | 1,572 | 1,583 | 1,590 | 1,644 | 1,683 | 1,694 |  |  |
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 | $ 1,509 | 1,497 | 1,488 | 1,465 | 1,407 | 1,220 | 676 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 599 |  |  |  |  |  |  |  |  |
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 | $ 368 | 369 | 376 | 391 | 388 | 380 | 383 |  |  |
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 | $ 321 | 306 | 290 | 259 | 220 | 166 | 76 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | 187 | 189 | 190 | 200 | 210 | 230 |  |  |
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 | 176 | 171 | 165 | 155 | 129 | $ 44 |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 1,073 | 1,086 | 1,127 | 1,122 | 1,108 | 1,109 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 358 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 587 | 553 | 506 | 422 | 286 | 107 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 299 |  |  |  |  |  |  |  |  |
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 | $ 3,209 | 3,423 | 3,526 | 3,536 | 3,536 | 3,541 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 748 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,229 | 2,004 | 1,594 | 1,190 | 547 | 129 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 19 |  |  |  |  |  |  |  |  |
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 | 468 | 515 | 522 | 530 | 526 |  |  |  |
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 | $ 411 | 385 | 348 | 270 | 196 | 68 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 18 |  |  |  |  |  |  |  |  |
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 | $ 1,334 | 1,335 | 1,354 | 1,331 | 1,418 | 1,428 |  |  |  |
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 | $ 1,319 | 1,306 | 1,280 | 1,233 | 1,134 | 648 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,073 |  |  |  |  |  |  |  |  |
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 | $ 1,927 | 1,915 | 1,890 | 1,887 | 1,879 | 1,851 |  |  |  |
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 | $ 1,876 | 1,834 | 1,778 | 1,679 | 1,496 | 1,038 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 126 |  |  |  |  |  |  |  |  |
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 | $ 1,192 | 1,227 | 1,283 | 1,240 | 1,243 | 1,247 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 221 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 796 | 695 | 559 | 414 | 260 | 85 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 44 |  |  |  |  |  |  |  |  |
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 | $ 1,619 | 1,649 | 1,659 | 1,705 | 1,773 | 1,780 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 42 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,550 | 1,531 | 1,495 | 1,464 | 1,271 | 695 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 620 |  |  |  |  |  |  |  |  |
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 | $ 321 | 328 | 327 | 327 | 324 | 318 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 30 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 258 | 240 | 221 | 185 | 142 | 64 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 140 | 142 | 141 | 146 | 158 | 160 |  |  |  |
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 | $ 134 | 132 | 129 | 119 | 102 | $ 46 |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 1,163 | 1,215 | 1,217 | 1,201 | 1,207 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 465 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 532 | 484 | 410 | 295 | 113 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 336 |  |  |  |  |  |  |  |  |
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 | $ 3,649 | 3,711 | 3,668 | 3,580 | 3,529 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,148 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,200 | 1,802 | 1,249 | 679 | 164 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 19 |  |  |  |  |  |  |  |  |
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 | $ 554 | 596 | 580 | 582 | 594 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 68 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 454 | 391 | 317 | 220 | 80 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 17 |  |  |  |  |  |  |  |  |
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 | $ 1,544 | 1,554 | 1,574 | 1,656 | 1,640 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 20 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,527 | 1,501 | 1,479 | 1,369 | 817 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,101 |  |  |  |  |  |  |  |  |
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 | $ 2,154 | 2,140 | 2,187 | 2,201 | 2,199 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 35 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,074 | 2,029 | 1,921 | 1,760 | 1,307 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 135 |  |  |  |  |  |  |  |  |
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 | $ 1,253 | 1,337 | 1,327 | 1,318 | 1,248 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 333 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 704 | 591 | 462 | 287 | 112 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 44 |  |  |  |  |  |  |  |  |
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 | $ 1,814 | 1,852 | 1,879 | 1,938 | 1,868 |  |  |  |  |
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 | $ 1,724 | 1,693 | 1,630 | 1,421 | 755 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 591 |  |  |  |  |  |  |  |  |
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 | $ 341 | 339 | 336 | 331 | 330 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 36 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 263 | 247 | 216 | 183 | 91 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 180 | 181 | 178 | 178 | 162 |  |  |  |  |
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 | $ 167 | 161 | 151 | 128 | $ 64 |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 1,279 | 1,276 | 1,259 | 1,282 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 594 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 501 | 418 | 301 | 116 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 334 |  |  |  |  |  |  |  |  |
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 | $ 3,968 | 3,812 | 3,702 | 3,553 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,570 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,853 | 1,204 | 604 | 138 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 21 |  |  |  |  |  |  |  |  |
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 | $ 514 | 501 | 469 | 486 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 148 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 304 | 214 | 137 | 47 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 15 |  |  |  |  |  |  |  |  |
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 | $ 1,634 | 1,646 | 1,741 | 1,732 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 39 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,553 | 1,485 | 1,340 | 725 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,170 |  |  |  |  |  |  |  |  |
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 | $ 2,538 | 2,555 | 2,544 | 2,489 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 48 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,386 | 2,266 | 2,079 | 1,495 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 139 |  |  |  |  |  |  |  |  |
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 | $ 1,314 | 1,293 | 1,267 | 1,170 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 387 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 659 | 482 | 282 | 86 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 46 |  |  |  |  |  |  |  |  |
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 | $ 2,036 | 2,071 | 2,117 | 1,992 |  |  |  |  |  |
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 | $ 1,853 | 1,772 | 1,548 | 850 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 621 |  |  |  |  |  |  |  |  |
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 | $ 297 | 296 | 286 | 281 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 30 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 215 | 190 | 157 | 89 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 160 | 160 | 153 | 145 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 8 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 142 | 132 | 103 | $ 56 |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 1,383 | 1,361 | 1,366 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 743 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 452 | 326 | 122 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 304 |  |  |  |  |  |  |  |  |
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 | $ 3,686 | 3,589 | 3,528 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 1,726 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,335 | 662 | 171 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 21 |  |  |  |  |  |  |  |  |
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 | $ 527 | 501 | 503 |  |  |  |  |  |  |
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 | $ 246 | 145 | 52 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 15 |  |  |  |  |  |  |  |  |
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 | $ 1,795 | 1,885 | 1,906 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 68 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,651 | 1,500 | 844 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,291 |  |  |  |  |  |  |  |  |
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 | $ 2,539 | 2,530 | 2,434 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 190 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,206 | 2,047 | 1,450 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 140 |  |  |  |  |  |  |  |  |
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 | $ 1,345 | 1,278 | 1,179 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 555 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 521 | 316 | 123 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 46 |  |  |  |  |  |  |  |  |
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 | $ 1,998 | 2,009 | 2,032 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 24 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,851 | 1,654 | 1,016 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 619 |  |  |  |  |  |  |  |  |
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 | $ 231 | 223 | 219 |  |  |  |  |  |  |
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 | $ 141 | 111 | 57 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 187 | 185 | 179 |  |  |  |  |  |  |
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 | $ 157 | 130 | $ 56 |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 1,380 | 1,412 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 831 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 313 | 120 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 338 |  |  |  |  |  |  |  |  |
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 | $ 3,492 | 3,317 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 2,442 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 616 | 161 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 21 |  |  |  |  |  |  |  |  |
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 | $ 565 | 531 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 265 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 175 | 66 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 16 |  |  |  |  |  |  |  |  |
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 | $ 2,604 | 2,700 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 207 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,084 | 977 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,372 |  |  |  |  |  |  |  |  |
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 | $ 3,064 | 3,029 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 291 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 2,515 | 1,694 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 144 |  |  |  |  |  |  |  |  |
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 | $ 1,287 | 1,186 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 676 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 314 | 96 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 44 |  |  |  |  |  |  |  |  |
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 | $ 2,236 | 2,199 |  |  |  |  |  |  |  |
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 | $ 1,822 | 1,040 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 659 |  |  |  |  |  |  |  |  |
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 | $ 211 | 210 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 65 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 99 | 46 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 422 | 396 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 32 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 322 | $ 191 |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 1,359 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 995 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 130 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 321 |  |  |  |  |  |  |  |  |
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 | $ 3,369 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 2,950 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 189 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 24 |  |  |  |  |  |  |  |  |
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 | $ 535 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 383 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 74 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 14 |  |  |  |  |  |  |  |  |
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 | $ 2,048 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 474 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,026 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,326 |  |  |  |  |  |  |  |  |
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 | $ 3,003 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 428 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 1,923 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 129 |  |  |  |  |  |  |  |  |
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 | $ 1,287 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 989 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 109 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 32 |  |  |  |  |  |  |  |  |
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 | $ 2,161 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 437 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 987 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 627 |  |  |  |  |  |  |  |  |
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 | $ 239 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 139 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 40 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |
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 | $ 283 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | 93 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 94 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 0 |  |  |  |  |  |  |  |  |

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