v3.26.1
Segment Information (Details) - Prior Year Development and Catastrophes - Reportable Segments [Member] - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment reporting information        
Net favorable prior year reserve development $ 578 $ 315 $ 991 $ 693
Catastrophe losses 518 927 1,279 3,193
Business Insurance [Member]        
Segment reporting information        
Net favorable prior year reserve development 319 79 481 153
Catastrophe losses 238 368 617 877
Bond & Specialty Insurance [Member]        
Segment reporting information        
Net favorable prior year reserve development 75 81 140 148
Catastrophe losses 4 5 12 24
Personal Insurance [Member]        
Segment reporting information        
Net favorable prior year reserve development 184 155 370 392
Catastrophe losses $ 276 $ 554 $ 650 $ 2,292