v3.25.4
SEGMENT REPORTING - Schedule of Underwriting Results for Segments (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Segment Reporting Information [Line Items]      
Gross written premiums $ 17,706 $ 18,232 $ 16,637
Net written premiums 15,513 15,814 14,730
Premiums earned 15,560 15,187 13,443
Incurred losses and LAE 10,859 11,305 8,427
Commission and brokerage 3,461 3,300 2,952
Other underwriting expenses 1,029 938 846
Underwriting gain (loss) 211 (356) 1,219
Net investment income 2,124 1,954 1,434
Net gains (losses) on investments (143) 19 (276)
Corporate expenses (109) (95) (73)
Interest, fee and bond issue cost amortization expense (151) (149) (134)
Other income (expense) (45) 121 (14)
INCOME (LOSS) BEFORE TAXES 1,887 1,493 2,154
Reinsurance      
Segment Reporting Information [Line Items]      
Gross written premiums 12,825 12,941 11,460
Net written premiums 11,791 11,969 10,802
Premiums earned 11,732 11,412 9,799
Incurred losses and LAE 7,517 7,103 5,690
Commission and brokerage 2,952 2,837 2,520
Other underwriting expenses 291 290 254
Underwriting gain (loss) 972 1,181 1,334
Insurance      
Segment Reporting Information [Line Items]      
Gross written premiums 4,790 5,078 4,888
Net written premiums 3,638 3,678 3,704
Premiums earned 3,718 3,579 3,420
Incurred losses and LAE 3,050 3,622 2,471
Commission and brokerage 488 439 410
Other underwriting expenses 721 615 556
Underwriting gain (loss) (541) (1,097) (18)
Other      
Segment Reporting Information [Line Items]      
Gross written premiums 91 212 289
Net written premiums 84 167 225
Premiums earned 111 197 225
Incurred losses and LAE 292 580 266
Commission and brokerage 21 24 22
Other underwriting expenses 17 33 35
Underwriting gain (loss) $ (220) $ (440) $ (98)