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Investment Information - Aging of available for sale securities in an unrealized loss position (Details) - USD ($) $ in Millions | Mar. 31, 2023 | Dec. 31, 2022
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Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | $ 6,934 | $ 12,976
Estimated Fair Value - 12 Months or More | 10,006 | 5,671
Estimated Fair Value | 16,940 | 18,647
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (266) | (929)
Gross Unrealized Losses - 12 Months or More | (1,032) | (720)
Gross Unrealized Losses | (1,298) | (1,649)
Fixed maturities |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 6,660 | 12,739
Estimated Fair Value - 12 Months or More | 10,006 | 5,671
Estimated Fair Value | 16,666 | 18,410
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (265) | (927)
Gross Unrealized Losses - 12 Months or More | (1,032) | (720)
Gross Unrealized Losses | (1,297) | (1,647)
Fixed maturities | Corporate bonds |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 2,723 | 4,823
Estimated Fair Value - 12 Months or More | 4,702 | 2,559
Estimated Fair Value | 7,425 | 7,382
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (101) | (393)
Gross Unrealized Losses - 12 Months or More | (535) | (388)
Gross Unrealized Losses | (636) | (781)
Fixed maturities | Residential mortgage backed securities |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 412 | 546
Estimated Fair Value - 12 Months or More | 279 | 154
Estimated Fair Value | 691 | 700
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (18) | (52)
Gross Unrealized Losses - 12 Months or More | (56) | (35)
Gross Unrealized Losses | (74) | (87)
Fixed maturities | Municipal bonds |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 131 | 364
Estimated Fair Value - 12 Months or More | 164 | 16
Estimated Fair Value | 295 | 380
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (6) | (30)
Gross Unrealized Losses - 12 Months or More | (18) | (3)
Gross Unrealized Losses | (24) | (33)
Fixed maturities | Commercial mortgage backed securities |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 167 | 598
Estimated Fair Value - 12 Months or More | 855 | 445
Estimated Fair Value | 1,022 | 1,043
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (8) | (35)
Gross Unrealized Losses - 12 Months or More | (46) | (23)
Gross Unrealized Losses | (54) | (58)
Fixed maturities | U.S. government and government agencies |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 1,209 | 3,557
Estimated Fair Value - 12 Months or More | 2,137 | 1,443
Estimated Fair Value | 3,346 | 5,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (40) | (197)
Gross Unrealized Losses - 12 Months or More | (194) | (146)
Gross Unrealized Losses | (234) | (343)
Fixed maturities | Non-U.S. government securities |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 1,109 | 1,703
Estimated Fair Value - 12 Months or More | 863 | 542
Estimated Fair Value | 1,972 | 2,245
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (61) | (154)
Gross Unrealized Losses - 12 Months or More | (117) | (84)
Gross Unrealized Losses | (178) | (238)
Fixed maturities | Asset backed securities |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 909 | 1,148
Estimated Fair Value - 12 Months or More | 1,006 | 512
Estimated Fair Value | 1,915 | 1,660
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (31) | (66)
Gross Unrealized Losses - 12 Months or More | (66) | (41)
Gross Unrealized Losses | (97) | (107)
Short-term investments |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 274 | 237
Estimated Fair Value - 12 Months or More | 0 | 0
Estimated Fair Value | 274 | 237
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (1) | (2)
Gross Unrealized Losses - 12 Months or More | 0 | 0
Gross Unrealized Losses | $ (1) | $ (2)

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