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Insurance - Short-duration insurance contracts, claims development (Details) - Property and casualty insurance $ in Millions | Dec. 31, 2024 USD ($) claim | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($)
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Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 27,160 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | 19,584 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE — 11th year and prior (excluding unallocated LAE) | 388 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | 7,964 |  |  |  |  |  |  |  |  |
Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 2,009 | $ 1,991 | $ 1,998 | $ 2,003 | $ 2,013 | $ 2,022 | $ 2,038 | $ 2,041 | $ 2,047 | $ 2,114
Total IBNR Plus Expected Development on Reported Claims | $ 50 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 231,366 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,924 | 1,909 | 1,878 | 1,847 | 1,791 | 1,722 | 1,592 | 1,404 | 1,129 | 619
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 95.80% |  |  |  |  |  |  |  |  |
Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,970 | 1,974 | 1,986 | 2,004 | 2,034 | 2,060 | 2,082 | 2,083 | 2,117 |
Total IBNR Plus Expected Development on Reported Claims | $ 68 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 223,427 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,865 | 1,848 | 1,806 | 1,750 | 1,662 | 1,539 | 1,350 | 1,099 | 577 |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 94.70% |  |  |  |  |  |  |  |  |
Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 2,283 | 2,266 | 2,256 | 2,269 | 2,301 | 2,329 | 2,348 | 2,375 |  |
Total IBNR Plus Expected Development on Reported Claims | $ 107 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 247,358 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 2,100 | 2,030 | 1,953 | 1,844 | 1,736 | 1,524 | 1,250 | 709 |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 92.00% |  |  |  |  |  |  |  |  |
Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 2,451 | 2,449 | 2,452 | 2,439 | 2,499 | 2,516 | 2,507 |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 165 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 237,209 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 2,178 | 2,099 | 1,977 | 1,807 | 1,606 | 1,337 | 730 |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 88.90% |  |  |  |  |  |  |  |  |
Accident Year 2019 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 2,657 | 2,642 | 2,632 | 2,672 | 2,674 | 2,721 |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 220 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 256,368 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 2,284 | 2,160 | 1,983 | 1,768 | 1,448 | 847 |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 86.00% |  |  |  |  |  |  |  |  |
Accident year 2020 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 2,512 | 2,500 | 2,546 | 2,635 | 2,748 |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 288 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 206,650 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 2,043 | 1,842 | 1,620 | 1,337 | 758 |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 81.30% |  |  |  |  |  |  |  |  |
Accident Year 2021 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 2,669 | 2,689 | 2,754 | 2,861 |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 467 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 208,142 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,958 | 1,687 | 1,368 | 746 |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 73.40% |  |  |  |  |  |  |  |  |
Accident Year 2022 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 3,204 | 3,205 | 3,270 |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 698 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 221,140 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 2,144 | 1,724 | 904 |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 66.90% |  |  |  |  |  |  |  |  |
Accident Year 2023 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 3,580 | 3,631 |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 1,121 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 230,821 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,950 | 989 |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 54.50% |  |  |  |  |  |  |  |  |
Accident Year 2024 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 3,825 |  |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 1,775 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 232,071 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,138 |  |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 29.80% |  |  |  |  |  |  |  |  |
Excludes short-duration insurance contracts detail for accident years not separately presented |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | $ 7,576 |  |  |  |  |  |  |  |  |
Property and transportation |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 10,482 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | 8,808 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE — 11th year and prior (excluding unallocated LAE) | 22 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | 1,696 |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 769 | 769 | 769 | 768 | 772 | 777 | 777 | 779 | 784 | 818
Total IBNR Plus Expected Development on Reported Claims | $ 3 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 135,094 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 762 | 761 | 755 | 750 | 744 | 736 | 707 | 667 | 582 | 359
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 99.10% |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 686 | 689 | 689 | 688 | 694 | 706 | 714 | 716 | 746 |
Total IBNR Plus Expected Development on Reported Claims | $ 5 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 121,410 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 674 | 672 | 665 | 656 | 640 | 618 | 577 | 521 | 294 |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 98.30% |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 817 | 820 | 820 | 816 | 823 | 843 | 847 | 889 |  |
Total IBNR Plus Expected Development on Reported Claims | $ 7 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 141,023 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 804 | 794 | 783 | 755 | 735 | 696 | 640 | 379 |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 98.40% |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 878 | 876 | 882 | 876 | 886 | 902 | 932 |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 9 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 130,781 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 852 | 838 | 824 | 781 | 738 | 676 | 396 |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 97.00% |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2019 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,059 | 1,057 | 1,055 | 1,051 | 1,058 | 1,111 |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 18 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 154,370 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,023 | 998 | 959 | 904 | 823 | 527 |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 96.60% |  |  |  |  |  |  |  |  |
Property and transportation | Accident year 2020 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 948 | 949 | 957 | 974 | 1,043 |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 22 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 122,246 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 896 | 857 | 804 | 726 | 461 |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 94.50% |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2021 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,028 | 1,022 | 1,023 | 1,119 |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 50 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 123,746 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 935 | 867 | 767 | 449 |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 91.00% |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2022 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,313 | 1,316 | 1,393 |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 100 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 137,902 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,119 | 1,018 | 587 |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 85.20% |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2023 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,392 | 1,472 |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 178 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 143,664 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,065 | 562 |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 76.50% |  |  |  |  |  |  |  |  |
Property and transportation | Accident Year 2024 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,592 |  |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 419 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 156,368 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 678 |  |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 42.60% |  |  |  |  |  |  |  |  |
Property and transportation | Excludes short-duration insurance contracts detail for accident years not separately presented |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | $ 1,674 |  |  |  |  |  |  |  |  |
Specialty casualty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 13,174 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | 8,259 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE — 11th year and prior (excluding unallocated LAE) | 351 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | 5,266 |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 1,019 | 1,002 | 1,007 | 1,015 | 1,021 | 1,024 | 1,042 | 1,041 | 1,043 | 1,081
Total IBNR Plus Expected Development on Reported Claims | $ 45 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 58,641 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 946 | 934 | 913 | 888 | 844 | 792 | 702 | 577 | 411 | 178
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 92.80% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,035 | 1,036 | 1,046 | 1,069 | 1,090 | 1,101 | 1,116 | 1,122 | 1,131 |
Total IBNR Plus Expected Development on Reported Claims | $ 57 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 56,831 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 951 | 938 | 906 | 870 | 806 | 713 | 584 | 418 | 186 |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 91.90% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,149 | 1,139 | 1,139 | 1,162 | 1,189 | 1,204 | 1,221 | 1,211 |  |
Total IBNR Plus Expected Development on Reported Claims | $ 88 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 57,492 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,007 | 959 | 902 | 833 | 755 | 612 | 422 | 200 |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 87.60% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,263 | 1,264 | 1,269 | 1,262 | 1,302 | 1,307 | 1,277 |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 137 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 59,615 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 1,046 | 991 | 901 | 794 | 649 | 475 | 210 |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 82.80% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2019 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,286 | 1,284 | 1,280 | 1,322 | 1,311 | 1,308 |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 178 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 60,028 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 994 | 913 | 795 | 651 | 455 | 212 |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 77.30% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident year 2020 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,232 | 1,232 | 1,258 | 1,329 | 1,352 |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 225 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 54,632 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 887 | 757 | 613 | 446 | 188 |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 72.00% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2021 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,319 | 1,342 | 1,389 | 1,384 |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 349 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 56,929 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 794 | 625 | 438 | 191 |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 60.20% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2022 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,516 | 1,503 | 1,475 |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 497 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 59,184 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 771 | 507 | 198 |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 50.90% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2023 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,670 | 1,648 |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 764 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 62,764 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 596 | 248 |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 35.70% |  |  |  |  |  |  |  |  |
Specialty casualty | Accident Year 2024 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 1,685 |  |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 1,067 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 55,113 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 267 |  |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 15.80% |  |  |  |  |  |  |  |  |
Specialty casualty | Excludes short-duration insurance contracts detail for accident years not separately presented |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | $ 4,915 |  |  |  |  |  |  |  |  |
Specialty financial |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 2,194 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | 1,781 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE — 11th year and prior (excluding unallocated LAE) | (8) |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | 405 |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 133 | 133 | 135 | 136 | 138 | 145 | 153 | 158 | 160 | 156
Total IBNR Plus Expected Development on Reported Claims | $ 0 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 37,631 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 132 | 133 | 134 | 134 | 134 | 132 | 133 | 129 | 110 | 72
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 99.20% |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 172 | 172 | 173 | 170 | 174 | 182 | 187 | 184 | 179 |
Total IBNR Plus Expected Development on Reported Claims | $ 0 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 45,186 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 172 | 172 | 171 | 164 | 163 | 161 | 158 | 141 | 88 |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 100.00% |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 210 | 210 | 202 | 203 | 208 | 212 | 215 | 212 |  |
Total IBNR Plus Expected Development on Reported Claims | $ 5 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 48,843 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 196 | 194 | 192 | 193 | 194 | 186 | 169 | 120 |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 93.30% |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 197 | 198 | 201 | 207 | 219 | 217 | 212 |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 5 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 46,813 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 193 | 193 | 192 | 188 | 187 | 163 | 112 |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 98.00% |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2019 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 178 | 182 | 186 | 191 | 198 | 194 |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 4 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 41,970 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 172 | 170 | 168 | 164 | 146 | 99 |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 96.60% |  |  |  |  |  |  |  |  |
Specialty financial | Accident year 2020 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 191 | 193 | 202 | 215 | 231 |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 12 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 29,772 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 167 | 162 | 159 | 144 | 100 |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 87.40% |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2021 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 179 | 187 | 201 | 223 |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 16 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 27,467 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 156 | 146 | 136 | 98 |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 87.20% |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2022 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 222 | 234 | 243 |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 29 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 24,054 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 187 | 164 | 108 |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 84.20% |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2023 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 329 | 310 |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 75 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 24,393 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 230 | 150 |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 69.90% |  |  |  |  |  |  |  |  |
Specialty financial | Accident Year 2024 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 383 |  |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 157 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 20,590 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 176 |  |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 46.00% |  |  |  |  |  |  |  |  |
Specialty financial | Excludes short-duration insurance contracts detail for accident years not separately presented |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | $ 413 |  |  |  |  |  |  |  |  |
Other specialty |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 1,310 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | 736 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE — 11th year and prior (excluding unallocated LAE) | 23 |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | 597 |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2015 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | 88 | 87 | 87 | 84 | 82 | 76 | 66 | 63 | 60 | 59
Total IBNR Plus Expected Development on Reported Claims | $ 2 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 84 | 81 | 76 | 75 | 69 | 62 | 50 | 31 | 26 | $ 10
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 95.50% |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2016 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 77 | 77 | 78 | 77 | 76 | 71 | 65 | 61 | 61 |
Total IBNR Plus Expected Development on Reported Claims | $ 6 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 68 | 66 | 64 | 60 | 53 | 47 | 31 | 19 | $ 9 |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 88.30% |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2017 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 107 | 97 | 95 | 88 | 81 | 70 | 65 | 63 |  |
Total IBNR Plus Expected Development on Reported Claims | $ 7 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 93 | 83 | 76 | 63 | 52 | 30 | 19 | $ 10 |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 86.90% |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2018 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 113 | 111 | 100 | 94 | 92 | 90 | 86 |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 14 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 87 | 77 | 60 | 44 | 32 | 23 | $ 12 |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 77.00% |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2019 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 134 | 119 | 111 | 108 | 107 | 108 |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 20 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 95 | 79 | 61 | 49 | 24 | $ 9 |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 70.90% |  |  |  |  |  |  |  |  |
Other specialty | Accident year 2020 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 141 | 126 | 129 | 117 | 122 |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 29 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 93 | 66 | 44 | 21 | $ 9 |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 66.00% |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2021 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 143 | 138 | 141 | 135 |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 52 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 73 | 49 | 27 | $ 8 |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 51.00% |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2022 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 153 | 152 | 159 |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 72 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 67 | 35 | $ 11 |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 43.80% |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2023 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 189 | 201 |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 104 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 59 | $ 29 |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 31.20% |  |  |  |  |  |  |  |  |
Other specialty | Accident Year 2024 |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Incurred Claims and Allocated LAE, Net of Reinsurance | $ 165 |  |  |  |  |  |  |  |  |
Total IBNR Plus Expected Development on Reported Claims | $ 132 |  |  |  |  |  |  |  |  |
Cumulative Number of Reported Claims | claim | 0 |  |  |  |  |  |  |  |  |
Cumulative Paid Claims and Allocated LAE, Net of Reinsurance | $ 17 |  |  |  |  |  |  |  |  |
Cumulative Percentage Paid of Incurred Claims and Allocated LAE, Net of Reinsurance | 10.30% |  |  |  |  |  |  |  |  |
Other specialty | Excludes short-duration insurance contracts detail for accident years not separately presented |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Unpaid losses and LAE, net of reinsurance (excluding unallocated LAE) | $ 574 |  |  |  |  |  |  |  |  |

X
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- Definition Undiscounted amount, after reinsurance, of incurred claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 9E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-9E Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 4B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-4B + Details
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