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Investment Information - Aging of available for sale securities in an unrealized loss position (Details) - USD ($) $ in Millions | Jun. 30, 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 | $ 10,327 | $ 12,976
Estimated Fair Value - 12 Months or More | 9,687 | 5,671
Estimated Fair Value | 20,014 | 18,647
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (301) | (929)
Gross Unrealized Losses - 12 Months or More | (1,031) | (720)
Gross Unrealized Losses | (1,332) | (1,649)
Fixed maturities |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 10,076 | 12,739
Estimated Fair Value - 12 Months or More | 9,687 | 5,671
Estimated Fair Value | 19,763 | 18,410
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (300) | (927)
Gross Unrealized Losses - 12 Months or More | (1,031) | (720)
Gross Unrealized Losses | (1,331) | (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 | 4,083 | 4,823
Estimated Fair Value - 12 Months or More | 5,184 | 2,559
Estimated Fair Value | 9,267 | 7,382
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (118) | (393)
Gross Unrealized Losses - 12 Months or More | (575) | (388)
Gross Unrealized Losses | (693) | (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 | 441 | 546
Estimated Fair Value - 12 Months or More | 330 | 154
Estimated Fair Value | 771 | 700
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (24) | (52)
Gross Unrealized Losses - 12 Months or More | (63) | (35)
Gross Unrealized Losses | (87) | (87)
Fixed maturities | Municipal bonds |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 126 | 364
Estimated Fair Value - 12 Months or More | 169 | 16
Estimated Fair Value | 295 | 380
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (7) | (30)
Gross Unrealized Losses - 12 Months or More | (20) | (3)
Gross Unrealized Losses | (27) | (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 | 127 | 598
Estimated Fair Value - 12 Months or More | 892 | 445
Estimated Fair Value | 1,019 | 1,043
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (4) | (35)
Gross Unrealized Losses - 12 Months or More | (45) | (23)
Gross Unrealized Losses | (49) | (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 | 3,362 | 3,557
Estimated Fair Value - 12 Months or More | 1,085 | 1,443
Estimated Fair Value | 4,447 | 5,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (61) | (197)
Gross Unrealized Losses - 12 Months or More | (115) | (146)
Gross Unrealized Losses | (176) | (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 | 1,242 | 1,703
Estimated Fair Value - 12 Months or More | 981 | 542
Estimated Fair Value | 2,223 | 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 | (143) | (84)
Gross Unrealized Losses | (204) | (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 | 695 | 1,148
Estimated Fair Value - 12 Months or More | 1,046 | 512
Estimated Fair Value | 1,741 | 1,660
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Gross Unrealized Losses - Less than 12 Months | (25) | (66)
Gross Unrealized Losses - 12 Months or More | (70) | (41)
Gross Unrealized Losses | (95) | (107)
Short-term investments |  |
Debt Securities, Available-for-sale, Unrealized Loss Position, Estimated Fair Value [Abstract] |  |
Estimated Fair Value - Less than 12 Months | 251 | 237
Estimated Fair Value - 12 Months or More | 0 | 0
Estimated Fair Value | 251 | 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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