Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Available For Sale Securities [Abstract]
Investment, Type [Extensible Enumeration]	Fixed Maturities [Member]	Fixed Maturities [Member]
Total available-for-sale, amortized cost	$ 1,688	$ 2,163
Allowance for Credit Losess	0	0
Gross unrealized gains	9	11
Gross unrealized losses	(140)	(243)
Total available-for-sale, fair value	1,557	1,931
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	721	541
Allowance for Credit Losess	0	0
Gross unrealized gains	1	5
Gross unrealized losses	(18)	(38)
Total available-for-sale, fair value	704	508
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	128	173
Allowance for Credit Losess	0	0
Gross unrealized gains	3	2
Gross unrealized losses	(8)	(11)
Total available-for-sale, fair value	123	164
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	19	23
Allowance for Credit Losess	0	0
Gross unrealized gains	1	0
Gross unrealized losses	(2)	(3)
Total available-for-sale, fair value	18	20
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	505	862
Allowance for Credit Losess	0	0
Gross unrealized gains	2	1
Gross unrealized losses	(90)	(148)
Total available-for-sale, fair value	417	715
Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	149	217
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(14)	(22)
Total available-for-sale, fair value	135	195
Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	31	96
Allowance for Credit Losess	0	0
Gross unrealized gains	1	3
Gross unrealized losses	(5)	(11)
Total available-for-sale, fair value	27	88
Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	13	24
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	0	(1)
Total available-for-sale, fair value	13	23
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	96	117
Allowance for Credit Losess	0	0
Gross unrealized gains	1	0
Gross unrealized losses	(1)	(5)
Total available-for-sale, fair value	96	112
Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	26	110
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(2)	(4)
Total available-for-sale, fair value	$ 24	$ 106

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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