Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 646	$ 325
Less than 12 months, unrealized losses	(26)	(3)
12 months or longer, fair value	88	91
12 months or longer, unrealized losses	(2)	(2)
Total available-for-sale, fair value	734	416
Total available-for-sale, unrealized losses	(28)	(5)
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	125	99
Less than 12 months, unrealized losses	(5)	(1)
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	125	99
Total available-for-sale, unrealized losses	(5)	(1)
US States And Political Subdivisions [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	4
Less than 12 months, unrealized losses	0
12 months or longer, fair value	0
12 months or longer, unrealized losses	0
Total available-for-sale, fair value	4
Total available-for-sale, unrealized losses	0
Foreign Government Debt [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	6	2
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	6	2
Total available-for-sale, unrealized losses	0	0
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	278	103
Less than 12 months, unrealized losses	(15)	(1)
12 months or longer, fair value	15	7
12 months or longer, unrealized losses	(1)	0
Total available-for-sale, fair value	293	110
Total available-for-sale, unrealized losses	(16)	(1)
Residential Mortgage Backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	100	53
Less than 12 months, unrealized losses	(3)	(1)
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	100	53
Total available-for-sale, unrealized losses	(3)	(1)
Residential Mortgage Backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	35	2
Less than 12 months, unrealized losses	(3)	0
12 months or longer, fair value	1	1
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	36	3
Total available-for-sale, unrealized losses	(3)	0
Commercial Mortgage Backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	2	0
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	0	5
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	2	5
Total available-for-sale, unrealized losses	0	0
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	19	37
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	71	78
12 months or longer, unrealized losses	(1)	(2)
Total available-for-sale, fair value	90	115
Total available-for-sale, unrealized losses	(1)	(2)
Other Asset Backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	77	29
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	1	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	78	29
Total available-for-sale, unrealized losses	$ 0	$ 0

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- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

+ References

No definition available.

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- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27337-111563

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

+ References

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

+ References

No definition available.

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This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

No definition available.

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