v3.26.1
Segment information (Details)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Segment Reporting [Line Items]        
Net premiums written $ 14,705 $ 14,196 $ 28,710 $ 26,842
Net premiums earned 13,889 13,125 27,346 25,125
Losses and loss expenses 6,691 6,572 12,822 13,468
Policy acquisition costs 2,632 2,415 5,228 4,728
Administrative expenses 1,168 1,125 2,317 2,205
Other (income) expense (196) (655) (357) (738)
Amortization of purchased intangibles 74 74 147 149
Segment Income (loss) 4,043 3,508 7,764 5,739
Net realized gains (losses) 162 160 (245) 44
Market risk benefits gains (losses) 5 (17) 19 (109)
Interest expense 200 181 398 362
Integration expenses and severance 8 2 17 2
Segment Reporting, Other Segment Item, Amount (64) (38) (40)  
Income before income tax $ 3,624 $ 3,716 $ 6,617 $ 5,380
Number of Reportable Segments 6 6 6 6
North America Commercial P&C Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written $ 5,594 $ 5,723 $ 10,489 $ 10,510
Net premiums earned 5,214 5,177 10,362 10,165
Losses and loss expenses 3,372 3,258 6,592 6,289
Policy benefits 0 0 0 0
Policy acquisition costs 730 705 1,482 1,424
Administrative expenses 351 357 705 701
Underwriting Income (Loss) 761 857 1,583 1,751
Segment Net Investment Income 982 938 1,953 1,867
Other (income) expense 15 8 29 16
Amortization of purchased intangibles 1 2 2 3
Segment Income (loss) 1,727 1,785 3,505 3,599
North American Personal P&C Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 2,054 1,938 3,735 3,490
Net premiums earned 1,817 1,681 3,563 3,255
Losses and loss expenses 791 822 1,825 2,915
Policy benefits 0 0 0 0
Policy acquisition costs 347 332 694 662
Administrative expenses 86 82 171 169
Underwriting Income (Loss) 593 445 873 (491)
Segment Net Investment Income 140 118 277 238
Other (income) expense 3 0 6 1
Amortization of purchased intangibles 2 2 4 4
Segment Income (loss) 728 561 1,140 (258)
North America Agricultural Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 776 733 1,087 1,009
Net premiums earned 641 598 830 763
Losses and loss expenses 526 483 579 575
Policy benefits 0 0 0 0
Policy acquisition costs 45 48 69 65
Administrative expenses 4 2 (2) 4
Underwriting Income (Loss) 66 65 184 119
Segment Net Investment Income 21 19 47 43
Other (income) expense 2 0 2 1
Amortization of purchased intangibles 6 6 12 12
Segment Income (loss) 79 78 217 149
Overseas General Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 3,990 3,620 8,456 7,523
Net premiums earned 3,984 3,542 7,764 6,751
Losses and loss expenses 1,709 1,789 3,361 3,186
Policy benefits 106 129 219 242
Policy acquisition costs 1,060 913 2,069 1,750
Administrative expenses 399 369 786 699
Underwriting Income (Loss) 710 342 1,329 874
Segment Net Investment Income 313 278 613 559
Other (income) expense 6 5 12 11
Amortization of purchased intangibles 22 19 44 38
Segment Income (loss) 995 596 1,886 1,384
Global Reinsurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 354 380 717 788
Net premiums earned 299 338 625 706
Losses and loss expenses 121 132 258 374
Policy benefits 0 0 0 0
Policy acquisition costs 98 98 200 198
Administrative expenses 8 10 17 20
Underwriting Income (Loss) 72 98 150 114
Segment Net Investment Income 110 85 218 155
Other (income) expense 0 0 0 0
Amortization of purchased intangibles 0 0 0 0
Segment Income (loss) 182 183 368 269
Life Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 1,937 1,802 4,226 3,522
Net premiums earned 1,934 1,789 4,202 3,485
Losses and loss expenses 22 20 50 46
Policy benefits 1,374 1,249 3,074 2,412
Policy acquisition costs 352 319 714 629
Administrative expenses 213 199 423 401
Segment Net Investment Income 323 274 628 545
Other (income) expense (45) (37) (96) (72)
Amortization of purchased intangibles 9 8 17 18
Segment Income (loss) 332 305 648 596
Segment Corporate and Other        
Segment Reporting [Line Items]        
Underwriting Income (Loss) (265) (176) (390) (295)
Segment Net Investment Income (10) (29) (21) (56)
Other (income) expense 5 (528) (13) (495)
Amortization of purchased intangibles $ 34 $ 37 $ 68 $ 74