v3.25.2
Segment Information (Details)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
USD ($)
Jun. 30, 2024
USD ($)
Jun. 30, 2025
USD ($)
segment
Jun. 30, 2024
USD ($)
Segment reporting information        
Number of reportable business segments | segment     3  
Premiums $ 10,921 $ 10,243 $ 21,631 $ 20,369
Net investment income 942 885 1,872 1,731
Fee income 124 115 243 224
Other revenues 123 105 235 217
Claims and claim adjustment expenses 6,789 7,373 14,795 14,029
Amortization of deferred acquisition costs 1,802 1,678 3,580 3,376
General and administrative expenses 1,545 1,478 3,004 2,884
Income tax expense (benefit) 372 122 445 369
Net realized investment gains (losses) 6 (65) (55) (30)
Total revenues 12,116 11,283 23,926 22,511
Core income (loss) 1,504 585 1,947 1,681
Net realized investment gains (losses), net of tax 5 (51) (43) (24)
Net income 1,509 534 1,904 1,657
Reportable Segments [Member]        
Segment reporting information        
Premiums 10,921 10,243 21,631 20,369
Net investment income 942 885 1,872 1,731
Fee income 124 115 243 224
Other revenues 123 105 235 217
Total segment revenues 12,110 11,348 23,981 22,541
Claims and claim adjustment expenses 6,789 7,373 14,795 14,029
Amortization of deferred acquisition costs 1,802 1,678 3,580 3,376
General and administrative expenses 1,533 1,466 2,981 2,864
Income tax expense (benefit) 395 158 505 420
Core income (loss) 1,591 673 2,120 1,852
Reportable Segments [Member] | Business Insurance [Member]        
Segment reporting information        
Premiums 5,545 5,168 11,010 10,328
Net investment income 662 632 1,318 1,241
Fee income 111 105 219 206
Other revenues 95 77 177 154
Total segment revenues 6,413 5,982 12,724 11,929
Claims and claim adjustment expenses 3,584 3,471 7,289 6,802
Amortization of deferred acquisition costs 944 861 1,861 1,725
General and administrative expenses 875 835 1,722 1,653
Income tax expense (benefit) 197 159 356 329
Core income (loss) 813 656 1,496 1,420
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member]        
Segment reporting information        
Premiums 5,083 4,736 10,065 9,483
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Workers' compensation [Member]        
Segment reporting information        
Premiums 841 864 1,664 1,744
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Automobile [Member]        
Segment reporting information        
Premiums 968 874 1,910 1,734
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Commercial property [Member]        
Segment reporting information        
Premiums 960 894 1,897 1,767
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | General liability [Member]        
Segment reporting information        
Premiums 862 845 1,723 1,692
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Commercial multi-peril [Member]        
Segment reporting information        
Premiums 1,435 1,246 2,835 2,516
Reportable Segments [Member] | Business Insurance [Member] | Domestic [Member] | Other [Member]        
Segment reporting information        
Premiums 17 13 36 30
Reportable Segments [Member] | Business Insurance [Member] | International [Member]        
Segment reporting information        
Premiums 462 432 945 845
Reportable Segments [Member] | Bond & Specialty Insurance [Member]        
Segment reporting information        
Premiums 1,021 977 2,016 1,933
Net investment income 107 94 209 184
Fee income 0 0 0 0
Other revenues 5 6 11 15
Total segment revenues 1,133 1,077 2,236 2,132
Claims and claim adjustment expenses 418 473 852 901
Amortization of deferred acquisition costs 195 183 382 365
General and administrative expenses 214 207 419 412
Income tax expense (benefit) 62 44 119 89
Core income (loss) 244 170 464 365
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member]        
Segment reporting information        
Premiums 885 845 1,753 1,667
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | General liability [Member]        
Segment reporting information        
Premiums 459 437 911 863
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | Fidelity and surety [Member]        
Segment reporting information        
Premiums 367 350 725 690
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | Domestic [Member] | Other [Member]        
Segment reporting information        
Premiums 59 58 117 114
Reportable Segments [Member] | Bond & Specialty Insurance [Member] | International [Member]        
Segment reporting information        
Premiums 136 132 263 266
Reportable Segments [Member] | Personal Insurance [Member]        
Segment reporting information        
Premiums 4,355 4,098 8,605 8,108
Net investment income 173 159 345 306
Fee income 13 10 24 18
Other revenues 23 22 47 48
Total segment revenues 4,564 4,289 9,021 8,480
Claims and claim adjustment expenses 2,787 3,429 6,654 6,326
Amortization of deferred acquisition costs 663 634 1,337 1,286
General and administrative expenses 444 424 840 799
Income tax expense (benefit) 136 (45) 30 2
Core income (loss) 534 (153) 160 67
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member]        
Segment reporting information        
Premiums 4,183 3,933 8,268 7,779
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member] | Automobile [Member]        
Segment reporting information        
Premiums 1,980 1,919 3,944 3,793
Reportable Segments [Member] | Personal Insurance [Member] | Domestic [Member] | Homeowners and Other [Member]        
Segment reporting information        
Premiums 2,203 2,014 4,324 3,986
Reportable Segments [Member] | Personal Insurance [Member] | International [Member]        
Segment reporting information        
Premiums 172 165 337 329
Other [Member]        
Segment reporting information        
Core income (loss) (87) (88) (173) (171)
After-tax interest expense $ 78 $ 78 $ 156 $ 155