Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions	Jun. 30, 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	$ 1,464	$ 1,688
Allowance for Credit Losess	0	0
Gross unrealized gains	5	9
Gross unrealized losses	(161)	(140)
Total available-for-sale, fair value	1,308	1,557
U.S. Treasury And Government Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	529	721
Allowance for Credit Losess	0	0
Gross unrealized gains	0	1
Gross unrealized losses	(20)	(18)
Total available-for-sale, fair value	509	704
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	116	128
Allowance for Credit Losess	0	0
Gross unrealized gains	2	3
Gross unrealized losses	(10)	(8)
Total available-for-sale, fair value	108	123
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	19	19
Allowance for Credit Losess	0	0
Gross unrealized gains	0	1
Gross unrealized losses	(2)	(2)
Total available-for-sale, fair value	17	18
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	510	505
Allowance for Credit Losess	0	0
Gross unrealized gains	1	2
Gross unrealized losses	(105)	(90)
Total available-for-sale, fair value	406	417
Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	138	149
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(17)	(14)
Total available-for-sale, fair value	121	135
Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	31	31
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	(6)	(5)
Total available-for-sale, fair value	26	27
Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	10	13
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Total available-for-sale, fair value	10	13
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	92	96
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	0	(1)
Total available-for-sale, fair value	93	96
Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	19	26
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(1)	(2)
Total available-for-sale, fair value	$ 18	$ 24

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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Amount, before tax, of unrealized loss 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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Amortized cost of 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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Amount of allowance for credit loss 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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