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Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Available For Sale Securities [Abstract]
Investment, Type [Extensible Enumeration]	Fixed Maturities [Member]	Fixed Maturities [Member]
Total available-for-sale, amortized cost	$ 1,391	$ 1,688
Allowance for Credit Losess	0	0
Gross unrealized gains	5	9
Gross unrealized losses	(160)	(140)
Total available-for-sale, fair value	1,236	1,557
U.S. Treasury And Government Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	500	721
Allowance for Credit Losess	0	0
Gross unrealized gains	0	1
Gross unrealized losses	(19)	(18)
Total available-for-sale, fair value	481	704
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	110	128
Allowance for Credit Losess	0	0
Gross unrealized gains	2	3
Gross unrealized losses	(11)	(8)
Total available-for-sale, fair value	101	123
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	12	19
Allowance for Credit Losess	0	0
Gross unrealized gains	0	1
Gross unrealized losses	(2)	(2)
Total available-for-sale, fair value	10	18
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	496	505
Allowance for Credit Losess	0	0
Gross unrealized gains	1	2
Gross unrealized losses	(106)	(90)
Total available-for-sale, fair value	391	417
Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	127	149
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(16)	(14)
Total available-for-sale, fair value	111	135
Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	36	31
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	(5)	(5)
Total available-for-sale, fair value	32	27
Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	7	13
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Total available-for-sale, fair value	7	13
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	71	96
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	0	(1)
Total available-for-sale, fair value	72	96
Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	32	26
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(1)	(2)
Total available-for-sale, fair value	$ 31	$ 24

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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