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Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - USD ($) $ in Millions | Mar. 31, 2024 | Dec. 31, 2023
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Available For Sale Securities [Abstract] |  |
Investment, Type [Extensible Enumeration] | Fixed Maturities [Member] | Fixed Maturities [Member]
Less than 12 months, fair value | $ 107 | $ 58
Less than 12 months, unrealized losses | (2) | (1)
12 months or longer, fair value | 763 | 796
12 months or longer, unrealized losses | (152) | (139)
Total, fair value | 870 | 854
Tota, unrealized losses | (154) | (140)
U.S. Treasury And Government Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 25 | 11
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 140 | 143
12 months or longer, unrealized losses | (20) | (18)
Total, fair value | 165 | 154
Tota, unrealized losses | (20) | (18)
State and municipal bonds [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 27 | 23
Less than 12 months, unrealized losses | (1) | (1)
12 months or longer, fair value | 58 | 57
12 months or longer, unrealized losses | (8) | (7)
Total, fair value | 85 | 80
Tota, unrealized losses | (9) | (8)
Foreign Governments [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 2 | 0
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 6 | 6
12 months or longer, unrealized losses | (2) | (2)
Total, fair value | 8 | 6
Tota, unrealized losses | (2) | (2)
Corporate Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 25 | 17
Less than 12 months, unrealized losses | (1) | 0
12 months or longer, fair value | 334 | 337
12 months or longer, unrealized losses | (97) | (90)
Total, fair value | 359 | 354
Tota, unrealized losses | (98) | (90)
Residential Mortgage backed Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 9 | 0
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 112 | 118
12 months or longer, unrealized losses | (17) | (14)
Total, fair value | 121 | 118
Tota, unrealized losses | (17) | (14)
Residential Mortgage Backed Non Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 3 | 3
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 21 | 21
12 months or longer, unrealized losses | (6) | (5)
Total, fair value | 24 | 24
Tota, unrealized losses | (6) | (5)
Commercial mortgage backed Securities [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 0 | 4
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 3 | 3
12 months or longer, unrealized losses | 0 | 0
Total, fair value | 3 | 7
Tota, unrealized losses | 0 | 0
Collateralized debt obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 0 | 0
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 72 | 89
12 months or longer, unrealized losses | (1) | (1)
Total, fair value | 72 | 89
Tota, unrealized losses | (1) | (1)
Other asset backed [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 16 | 0
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 17 | 22
12 months or longer, unrealized losses | (1) | (2)
Total, fair value | 33 | 22
Tota, unrealized losses | $ (1) | $ (2)

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