Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Available For Sale Securities [Abstract]
Investment, Type [Extensible Enumeration]	Fixed Maturities [Member]	Fixed Maturities [Member]
Total available-for-sale, amortized cost	$ 1,400	$ 1,391
Allowance for Credit Losess	0	0
Gross unrealized gains	6	5
Gross unrealized losses	(138)	(160)
Total available-for-sale, fair value	1,268	1,236
U.S. Treasury And Government Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	536	500
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(12)	(19)
Total available-for-sale, fair value	524	481
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	106	110
Allowance for Credit Losess	0	0
Gross unrealized gains	2	2
Gross unrealized losses	(9)	(11)
Total available-for-sale, fair value	99	101
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	7	12
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(2)	(2)
Total available-for-sale, fair value	5	10
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	436	496
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	(99)	(106)
Total available-for-sale, fair value	338	391
Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	126	127
Allowance for Credit Losess	0	0
Gross unrealized gains	1	0
Gross unrealized losses	(13)	(16)
Total available-for-sale, fair value	114	111
Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	13	36
Allowance for Credit Losess	0	0
Gross unrealized gains	0	1
Gross unrealized losses	(1)	(5)
Total available-for-sale, fair value	12	32
Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	14	7
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Total available-for-sale, fair value	14	7
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	40	71
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	0	0
Total available-for-sale, fair value	41	72
Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	122	32
Allowance for Credit Losess	0	0
Gross unrealized gains	1	0
Gross unrealized losses	(2)	(1)
Total available-for-sale, fair value	$ 121	$ 31

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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