v3.26.3
Segment information (Details)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Segment Reporting [Line Items]        
Net premiums written $ 15,143 $ 14,866 $ 43,853 $ 41,708
Net premiums earned 14,924 14,359 42,270 39,484
Losses and loss expenses 7,526 6,951 20,348 20,419
Policy acquisition costs 2,739 2,563 7,967 7,291
Administrative expenses 1,126 1,138 3,443 3,343
Other (income) expense (364) (43) (721) (781)
Amortization of purchased intangibles 74 75 221 224
Segment Income (loss) 4,122 4,242 11,931 10,025
Net realized gains (losses) (455) 283 (700) 327
Market risk benefits gains (losses) (65) (142) (46) (251)
Interest expense 204 197 602 559
Integration expenses and severance 11 1 28 3
Segment Reporting, Other Segment Item, Amount (27) 48 (67) 48
Income before income tax $ 3,402 $ 3,894 $ 10,019 $ 9,274
Number of Reportable Segments 6 6 6 6
North America Commercial P&C Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written $ 5,512 $ 5,663 $ 16,001 $ 16,173
Net premiums earned 5,222 5,080 15,584 15,245
Losses and loss expenses 3,422 3,083 10,014 9,372
Policy benefits 0 0 0 0
Policy acquisition costs 750 708 2,232 2,132
Administrative expenses 333 348 1,038 1,049
Underwriting Income (Loss) 717 941 2,300 2,692
Segment Net Investment Income 985 978 2,938 2,845
Other (income) expense 17 10 46 26
Amortization of purchased intangibles 0 0 [1] 0 0 [1]
Segment Income (loss) 1,685 1,909 5,192 5,511
North American Personal P&C Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 1,909 1,814 5,644 5,304
Net premiums earned 1,846 1,741 5,409 4,996
Losses and loss expenses 668 713 2,493 3,628
Policy benefits 0 0 0 0
Policy acquisition costs 359 339 1,053 1,001
Administrative expenses 87 82 258 251
Underwriting Income (Loss) 732 607 1,605 116
Segment Net Investment Income 143 123 420 361
Other (income) expense 3 1 9 2
Amortization of purchased intangibles 0 0 [1] 0 0 [1]
Segment Income (loss) 872 729 2,016 475
North America Agricultural Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 1,532 1,458 2,619 2,467
Net premiums earned 1,559 1,495 2,389 2,258
Losses and loss expenses 1,306 1,224 1,885 1,799
Policy benefits 0 0 0 0
Policy acquisition costs 84 86 153 151
Administrative expenses 2 5 0 9
Underwriting Income (Loss) 167 180 351 299
Segment Net Investment Income 21 20 68 63
Other (income) expense 1 0 3 1
Amortization of purchased intangibles 0 0 [1] 0 0 [1]
Segment Income (loss) 187 200 416 361
Overseas General Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 3,943 3,695 12,399 11,218
Net premiums earned 4,053 3,803 11,817 10,554
Losses and loss expenses 1,910 1,707 5,271 4,893
Policy benefits 124 119 343 361
Policy acquisition costs 1,085 975 3,154 2,725
Administrative expenses 383 368 1,169 1,067
Underwriting Income (Loss) 551 634 1,880 1,508
Segment Net Investment Income 318 288 931 847
Other (income) expense 14 8 26 19
Amortization of purchased intangibles 15 13 [1] 43 39 [1]
Segment Income (loss) 840 901 2,742 2,297
Global Reinsurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 287 304 1,004 1,092
Net premiums earned 287 315 912 1,021
Losses and loss expenses 130 139 388 513
Policy benefits 0 0 0 0
Policy acquisition costs 93 96 293 294
Administrative expenses 9 9 26 29
Underwriting Income (Loss) 55 71 205 185
Segment Net Investment Income 114 100 332 255
Other (income) expense 0 0 0 0
Amortization of purchased intangibles 0 0 [1] 0 0 [1]
Segment Income (loss) 169 171 537 440
Life Insurance [Member]        
Segment Reporting [Line Items]        
Net premiums written 1,960 1,932 6,186 5,454
Net premiums earned 1,957 1,925 6,159 5,410
Losses and loss expenses 34 31 84 77
Policy benefits 1,355 1,303 4,429 3,715
Policy acquisition costs 368 359 1,082 988
Administrative expenses 202 213 625 614
Segment Net Investment Income 321 284 949 829
Other (income) expense (52) (31) (148) (103)
Amortization of purchased intangibles 2 2 [1] 8 7 [1]
Segment Income (loss) 369 332 1,028 941
Segment Corporate and Other        
Segment Reporting [Line Items]        
Underwriting Income (Loss) (161) (174) (551) (469)
Segment Net Investment Income (14) (18) (35) (74)
Other (income) expense (274) 87 (287) (408)
Amortization of purchased intangibles $ 57 $ 60 [1] $ 170 $ 178 [1]
[1] Recast to exclude amortization expense related to certain intangible assets acquired through business combinations from reportable segment results.