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Segment information (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | $ 11,951 | $ 10,293 | $ 22,661 | $ 19,482
Net premiums earned | 10,999 | 9,549 | 21,141 | 18,286
Losses and loss expenses | 5,683 | 5,206 | 10,831 | 9,770
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | 830 | 361 | 1,627 | 734
Policy acquisition costs | 2,016 | 1,726 | 3,964 | 3,445
Administrative expenses | 969 | 818 | 1,899 | 1,596
Underwriting income (loss) | 1,501 | 1,438 | 2,820 | 2,741
Net investment income (loss) | 1,145 | 888 | 2,252 | 1,710
Other (income) expense | (100) | 101 | (396) | (211)
Amortization of purchased intangibles | 70 | 71 | 142 | 142
Segment Income (loss) | 2,676 | 2,154 | 5,326 | 4,520
Net realized gains (losses) | (304) | (503) | (381) | (480)
Market risk benefits gains (losses) | (7) | (33) | (122) | 16
Interest Income (Expense), Net | 165 | 134 | 325 | 266
Cigna integration expenses | 15 | 3 | 37 | 3
Income tax expense | 392 | 291 | 776 | 644
Net income | 1,793 | 1,190 | 3,685 | 3,143
Segment Reconciling Items |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 0 | 0 | 0 | 0
Net premiums earned | 0 | 0 | 0 | 0
Losses and loss expenses | 5 | 9 | 4 | 10
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | (12) | (18) | (37) | (49)
Policy acquisition costs | 0 | 0 | 0 | 0
Administrative expenses | 0 | 0 | 0 | 0
Underwriting income (loss) | 7 | 9 | 33 | 39
Net investment income (loss) | (93) | (48) | (184) | (111)
Other (income) expense | (81) | (30) | (147) | (62)
Amortization of purchased intangibles | 0 | 0 | 0 | 0
Segment Income (loss) | (5) | (9) | (4) | (10)
Net realized gains (losses) | 5 | 9 | 4 | 10
Market risk benefits gains (losses) | 0 | 0 | 0 | 0
Interest Income (Expense), Net | 0 | 0 | 0 | 0
Cigna integration expenses | 0 | 0 | 0 | 0
Income tax expense | 0 | 0 | 0 | 0
Net income | 0 | 0 | 0 | 0
North America Commercial P&C Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written |  | 4,665 |  | 8,704
Net premiums earned |  | 4,248 |  | 8,362
Losses and loss expenses |  | 2,446 |  | 4,943
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) |  | 0 |  | 0
Policy acquisition costs |  | 545 |  | 1,118
Administrative expenses |  | 277 |  | 542
Underwriting income (loss) |  | 980 |  | 1,759
Net investment income (loss) |  | 522 |  | 1,011
Other (income) expense |  | 0 |  | 6
Amortization of purchased intangibles |  | 0 |  | 0
Segment Income (loss) |  | 1,502 |  | 2,764
North America Personal P&C Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written |  | 1,426 |  | 2,606
Net premiums earned |  | 1,271 |  | 2,518
Losses and loss expenses |  | 773 |  | 1,486
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) |  | 0 |  | 0
Policy acquisition costs |  | 258 |  | 518
Administrative expenses |  | 73 |  | 142
Underwriting income (loss) |  | 167 |  | 372
Net investment income (loss) |  | 64 |  | 123
Other (income) expense |  | 1 |  | 2
Amortization of purchased intangibles |  | 3 |  | 5
Segment Income (loss) |  | 227 |  | 488
North America Agricultural Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 767 | 738 | 1,060 | 800
Net premiums earned | 635 | 573 | 794 | 544
Losses and loss expenses | 507 | 478 | 647 | 386
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | 0 | 0 | 0 | 0
Policy acquisition costs | 37 | 31 | 52 | 43
Administrative expenses | 3 | 2 | 6 | 1
Underwriting income (loss) | 88 | 62 | 89 | 114
Net investment income (loss) | 14 | 7 | 31 | 14
Other (income) expense | (1) | 0 | 0 | 0
Amortization of purchased intangibles | 7 | 6 | 13 | 13
Segment Income (loss) | 96 | 63 | 107 | 115
Overseas General Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 2,885 | 2,640 | 6,148 | 5,719
Net premiums earned | 2,908 | 2,696 | 5,694 | 5,324
Losses and loss expenses | 1,267 | 1,143 | 2,504 | 2,439
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | 137 | 81 | 247 | 174
Policy acquisition costs | 746 | 697 | 1,459 | 1,376
Administrative expenses | 292 | 278 | 572 | 547
Underwriting income (loss) | 466 | 497 | 912 | 788
Net investment income (loss) | 200 | 162 | 388 | 309
Other (income) expense | (10) | 3 | (19) | 5
Amortization of purchased intangibles | 15 | 14 | 33 | 28
Segment Income (loss) | 661 | 642 | 1,286 | 1,064
Global Reinsurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 293 | 262 | 570 | 515
Net premiums earned | 237 | 222 | 481 | 457
Losses and loss expenses | 91 | 139 | 203 | 254
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | 0 | 0 | 0 | 0
Policy acquisition costs | 65 | 57 | 127 | 119
Administrative expenses | 9 | 10 | 18 | 19
Underwriting income (loss) | 72 | 16 | 133 | 65
Net investment income (loss) | 48 | 76 | 97 | 161
Other (income) expense | 0 | 1 | (1) | 1
Amortization of purchased intangibles | 0 | 0 | 0 | 0
Segment Income (loss) | 120 | 91 | 231 | 225
Life Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 1,270 | 562 | 2,563 | 1,138
Net premiums earned | 1,256 | 539 | 2,520 | 1,081
Losses and loss expenses | 35 | 27 | 67 | 51
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | 705 | 298 | 1,417 | 609
Policy acquisition costs | 277 | 138 | 550 | 271
Administrative expenses | 170 | 88 | 337 | 172
Underwriting income (loss) | 69 | (12) | 149 | (22)
Net investment income (loss) | 161 | 109 | 314 | 212
Other (income) expense | (26) | (12) | (41) | (42)
Amortization of purchased intangibles | 2 | 3 | 6 | 5
Segment Income (loss) | 254 | 106 | 498 | 227
Segment Corporate and Other |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 0 | 0 | 0 | 0
Net premiums earned | 0 | 0 | 0 | 0
Losses and loss expenses | 61 | 191 | 72 | 201
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | 0 | 0 | 0 | 0
Policy acquisition costs | 0 | 0 | 0 | 0
Administrative expenses | 95 | 90 | 192 | 173
Underwriting income (loss) | (156) | (281) | (264) | (374)
Net investment income (loss) | 3 | (4) | 14 | (9)
Other (income) expense | 14 | 138 | (200) | (121)
Amortization of purchased intangibles | 43 | 45 | 85 | 91
Segment Income (loss) | (210) | (468) | (135) | (353)
Net realized gains (losses) | (309) | (512) | (385) | (490)
Market risk benefits gains (losses) | (7) | (33) | (122) | 16
Interest Income (Expense), Net | 165 | 134 | 325 | 266
Cigna integration expenses | 15 | 3 | 37 | 3
Income tax expense | 392 | 291 | 776 | 644
Net income | (1,098) | $ (1,441) | (1,780) | $ (1,740)
North America Commercial P&C Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 5,155 |  | 9,443 |
Net premiums earned | 4,606 |  | 8,975 |
Losses and loss expenses | 2,871 |  | 5,600 |
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | 0 |  | 0 |
Policy acquisition costs | 614 |  | 1,227 |
Administrative expenses | 316 |  | 611 |
Underwriting income (loss) | 805 |  | 1,537 |
Net investment income (loss) | 726 |  | 1,424 |
Other (income) expense | 5 |  | 12 |
Amortization of purchased intangibles | 0 |  | 0 |
Segment Income (loss) | 1,526 |  | 2,949 |
Segment Insurance North American Personal P&C |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 1,581 |  | 2,877 |
Net premiums earned | 1,357 |  | 2,677 |
Losses and loss expenses | 846 |  | 1,734 |
Policy benefits (includes remeasurement losses of $5, nil, $4, and $6) | 0 |  | 0 |
Policy acquisition costs | 277 |  | 549 |
Administrative expenses | 84 |  | 163 |
Underwriting income (loss) | 150 |  | 231 |
Net investment income (loss) | 86 |  | 168 |
Other (income) expense | (1) |  | 0 |
Amortization of purchased intangibles | 3 |  | 5 |
Segment Income (loss) | $ 234 |  | $ 394 |

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