Investments (Amortized Cost And Fair Value Of Available-For-Sale and Held-To-Maturity Investment Portfolios) (Detail) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	$ 453	$ 541
Allowance for Credit Losess	0	0
Gross unrealized gains	6	5
Gross unrealized losses	(34)	(38)
Total available-for-sale, fair value	425	508
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	134	173
Allowance for Credit Losess	0	0
Gross unrealized gains	2	2
Gross unrealized losses	(10)	(11)
Total available-for-sale, fair value	126	164
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	25	23
Allowance for Credit Losess	0	0
Gross unrealized gains	1	0
Gross unrealized losses	(2)	(3)
Total available-for-sale, fair value	24	20
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	899	862
Allowance for Credit Losess	0	0
Gross unrealized gains	1	1
Gross unrealized losses	(123)	(148)
Total available-for-sale, fair value	777	715
Residential Mortgage-Backed Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	207	217
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(21)	(22)
Total available-for-sale, fair value	186	195
Residential Mortgage-Backed Non-Agency [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	54	96
Allowance for Credit Losess	0	0
Gross unrealized gains	2	3
Gross unrealized losses	(6)	(11)
Total available-for-sale, fair value	50	88
Commercial Mortgage-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	23	24
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(1)	(1)
Total available-for-sale, fair value	22	23
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	114	117
Allowance for Credit Losess	0	0
Gross unrealized gains	1	0
Gross unrealized losses	(3)	(5)
Total available-for-sale, fair value	112	112
Other Asset-Backed [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	53	110
Allowance for Credit Losess	0	0
Gross unrealized gains	0	0
Gross unrealized losses	(3)	(4)
Total available-for-sale, fair value	50	106
Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Total available-for-sale, amortized cost	1,962	2,163
Allowance for Credit Losess	0	0
Gross unrealized gains	13	11
Gross unrealized losses	(203)	(243)
Total available-for-sale, fair value	$ 1,772	$ 1,931

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).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
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