v3.26.1
OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Reclassification from Accumulated Other Comprehensive Income (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Other net gains (losses) on investments $ (8) $ (2) $ (38) $ 93
Income tax expense (benefit) (72) (65) (167) (89)
Other underwriting expenses (130) (146) (249) (296)
NET INCOME (LOSS) 305 324 738 424
URA(D) of securities | Reclassification from Accumulated Other Comprehensive Income        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Other net gains (losses) on investments 10 2 10 5
Income tax expense (benefit) (2) 0 (2) (1)
NET INCOME (LOSS) 8 2 8 4
Benefit plan net gain (loss) | Reclassification from Accumulated Other Comprehensive Income        
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]        
Income tax expense (benefit) 0 6 0 6
Other underwriting expenses 0 (28) (1) (28)
NET INCOME (LOSS) $ 0 $ (22) $ (1) $ (22)