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Segment Information (Operations By Segment) (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Segment Reporting Information [Line Items] |  |  |
Net premiums written | $ 41,755 | $ 37,868 | $ 33,820
Net premiums earned | 40,389 | 36,355 | 33,117
Losses and loss expenses | 23,342 | 21,980 | 21,710
Policy benefits | 1,492 | 699 | 784
Policy acquisition costs | 7,392 | 6,918 | 6,547
Administrative expenses | 3,395 | 3,136 | 2,979
Underwriting Income (Loss) | 4,768 | 3,622 | 1,097
Net investment income | 3,742 | 3,456 | 3,375
Other (income) expense | 74 | (2,365) | (994)
Amortization of purchased intangibles | 285 | 287 | 290
Segment income (loss) | 8,151 | 9,156 | 5,176
Net realized gains (losses) | (965) | 1,152 | (498)
Interest expense | 570 | 492 | 516
Income tax expense | 1,255 | 1,277 | 629
Cigna integration expenses | 48 | 0 | 0
Net income | 5,313 | 8,539 | 3,533
Segment Reconciling Items [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net premiums written | 0 | 0 | 0
Net premiums earned | 0 | 0 | 0
Losses and loss expenses | (11) | (8) | 1
Policy benefits | (42) | (8) | 58
Policy acquisition costs | 0 | 0 | 0
Administrative expenses | 0 | 0 | 0
Underwriting Income (Loss) | 53 | 16 | (59)
Net investment income | (240) | (179) | (115)
Other (income) expense | (198) | (171) | (173)
Amortization of purchased intangibles | 0 | 0 | 0
Segment income (loss) | 11 | 8 | (1)
Net realized gains (losses) | (11) | (8) | 1
Interest expense | 0 | 0 | 0
Income tax expense | 0 | 0 | 0
Cigna integration expenses | 0 |  |
Net income | 0 | 0 | 0
North America Commercial P&C Insurance [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net premiums written | 17,889 | 16,415 | 14,474
Net premiums earned | 17,107 | 15,461 | 13,964
Losses and loss expenses | 10,828 | 10,015 | 10,129
Policy benefits | 0 | 0 | 0
Policy acquisition costs | 2,313 | 2,082 | 1,942
Administrative expenses | 1,113 | 1,052 | 1,006
Underwriting Income (Loss) | 2,853 | 2,312 | 887
Net investment income | 2,247 | 2,078 | 2,061
Other (income) expense | 17 | 31 | 23
Amortization of purchased intangibles | 0 | 0 | 0
Segment income (loss) | 5,083 | 4,359 | 2,925
North America Personal P&C Insurance [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net premiums written | 5,313 | 5,002 | 4,920
Net premiums earned | 5,180 | 4,915 | 4,866
Losses and loss expenses | 3,186 | 2,924 | 3,187
Policy benefits | 0 | 0 | 0
Policy acquisition costs | 1,057 | 1,001 | 974
Administrative expenses | 291 | 276 | 270
Underwriting Income (Loss) | 646 | 714 | 435
Net investment income | 283 | 249 | 260
Other (income) expense | 4 | (2) | 5
Amortization of purchased intangibles | 10 | 10 | 11
Segment income (loss) | 915 | 955 | 679
North America Agricultural Insurance [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net premiums written | 2,907 | 2,388 | 1,846
Net premiums earned | 2,838 | 2,338 | 1,822
Losses and loss expenses | 2,557 | 1,962 | 1,544
Policy benefits | 0 | 0 | 0
Policy acquisition costs | 126 | 124 | 123
Administrative expenses | (10) | (3) | 9
Underwriting Income (Loss) | 165 | 255 | 146
Net investment income | 36 | 28 | 30
Other (income) expense | 1 | 1 | 1
Amortization of purchased intangibles | 26 | 26 | 27
Segment income (loss) | 174 | 256 | 148
Overseas General Insurance [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net premiums written | 11,060 | 10,713 | 9,335
Net premiums earned | 10,803 | 10,441 | 9,285
Losses and loss expenses | 5,252 | 5,143 | 5,255
Policy benefits | 0 | 0 | 0
Policy acquisition costs | 2,818 | 2,799 | 2,568
Administrative expenses | 1,070 | 1,078 | 1,034
Underwriting Income (Loss) | 1,663 | 1,421 | 428
Net investment income | 626 | 597 | 534
Other (income) expense | 2 | 0 | 13
Amortization of purchased intangibles | 57 | 48 | 45
Segment income (loss) | 2,230 | 1,970 | 904
Global Reinsurance [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net premiums written | 943 | 873 | 731
Net premiums earned | 922 | 798 | 698
Losses and loss expenses | 670 | 632 | 435
Policy benefits | 0 | 0 | 0
Policy acquisition costs | 240 | 200 | 174
Administrative expenses | 36 | 35 | 37
Underwriting Income (Loss) | (24) | (69) | 52
Net investment income | 281 | 331 | 307
Other (income) expense | 1 | 0 | 2
Amortization of purchased intangibles | 0 | 0 | 0
Segment income (loss) | 256 | 262 | 357
Life Insurance [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net premiums written | 3,643 | 2,477 | 2,514
Net premiums earned | 3,539 | 2,402 | 2,482
Losses and loss expenses | 497 | 740 | 724
Policy benefits | 1,534 | 707 | 726
Policy acquisition costs | 838 | 712 | 766
Administrative expenses | 510 | 333 | 320
Underwriting Income (Loss) | 160 | (90) | (54)
Net investment income | 509 | 407 | 385
Other (income) expense | (45) | (106) | (74)
Amortization of purchased intangibles | 10 | 5 | 4
Segment income (loss) | 704 | 418 | 401
Corporate and Other |  |  |
Segment Reporting Information [Line Items] |  |  |
Net premiums written | 0 | 0 | 0
Net premiums earned | 0 | 0 | 0
Losses and loss expenses | 363 | 572 | 435
Policy benefits | 0 | 0 | 0
Policy acquisition costs | 0 | 0 | 0
Administrative expenses | 385 | 365 | 303
Underwriting Income (Loss) | (748) | (937) | (738)
Net investment income | 0 | (55) | (87)
Other (income) expense | 292 | (2,118) | (791)
Amortization of purchased intangibles | 182 | 198 | 203
Segment income (loss) | (1,222) | 928 | (237)
Net realized gains (losses) | (954) | 1,160 | (499)
Interest expense | 570 | 492 | 516
Income tax expense | 1,255 | 1,277 | 629
Cigna integration expenses | 48 |  |
Net income | $ (4,049) | $ 319 | $ (1,881)

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