Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	$ 749	$ 782
Allowance for Credit Losess	0	0
Gross unrealized gains	6	54
Gross unrealized losses	(39)	(2)
Total available-for-sale, fair value	716	834
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	143	140
Allowance for Credit Losess	0	0
Gross unrealized gains	1	27
Gross unrealized losses	(12)	0
Total available-for-sale, fair value	132	167
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	23	13
Allowance for Credit Losess	0	0
Gross unrealized gains	0	1
Gross unrealized losses	(4)	0
Total available-for-sale, fair value	19	14
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	872	905
Allowance for Credit Losess	0	0
Gross unrealized gains	1	53
Gross unrealized losses	(162)	(5)
Total available-for-sale, fair value	711	953
Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	207	190
Allowance for Credit Losess	0	0
Gross unrealized gains	0	3
Gross unrealized losses	(25)	(1)
Total available-for-sale, fair value	182	192
Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	135	80
Allowance for Credit Losess	0	0
Gross unrealized gains	2	12
Gross unrealized losses	(19)	0
Total available-for-sale, fair value	118	92
Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	13	10
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(1)	0
Total available-for-sale, fair value	12	10
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	118	101
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(7)	0
Total available-for-sale, fair value	111	101
Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	109	95
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(4)	(1)
Total available-for-sale, fair value	105	94
Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	2,369	2,316
Allowance for Credit Losess	0	0
Gross unrealized gains	10	150
Gross unrealized losses	(273)	(9)
Total available-for-sale, fair value	$ 2,106	$ 2,457

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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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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Amortized cost, after allowance for credit loss, 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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