Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Available For Sale Securities [Abstract]
Investment, Type [Extensible Enumeration]	Fixed Maturities [Member]	Fixed Maturities [Member]
Total available-for-sale, amortized cost	$ 1,489	$ 1,464
Allowance for Credit Losess	0	0
Gross unrealized gains	5	7
Gross unrealized losses	(136)	(129)
Total available-for-sale, fair value	1,358	1,342
U.S. Treasury And Government Agency [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	448	478
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(10)	(10)
Total available-for-sale, fair value	438	468
US States And Political Subdivisions [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	106	106
Allowance for Credit Losess	0	0
Gross unrealized gains	2	3
Gross unrealized losses	(9)	(8)
Total available-for-sale, fair value	99	101
Foreign Governments [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	7	7
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(2)	(2)
Total available-for-sale, fair value	5	5
Corporate Obligations [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	504	462
Allowance for Credit Losess	0	0
Gross unrealized gains	0	1
Gross unrealized losses	(101)	(96)
Total available-for-sale, fair value	403	367
Residential Mortgage-Backed Agency [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	119	125
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(11)	(11)
Total available-for-sale, fair value	108	114
Residential Mortgage-Backed Non-Agency [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	17	17
Allowance for Credit Losess	0	0
Gross unrealized gains	1	0
Gross unrealized losses	(1)	(1)
Total available-for-sale, fair value	17	16
Commercial Mortgage-Backed [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	8	10
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Total available-for-sale, fair value	8	10
Collateralized Debt Obligations [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	63	30
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	0	0
Total available-for-sale, fair value	64	31
Other Asset-Backed [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	217	229
Allowance for Credit Losess	0	0
Gross unrealized gains	1	2
Gross unrealized losses	(2)	(1)
Total available-for-sale, fair value	$ 216	$ 230

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 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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