Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 521	$ 325
Less than 12 months, unrealized losses	(7)	(3)
12 months or longer, fair value	58	91
12 months or longer, unrealized losses	(1)	(2)
Total available-for-sale, fair value	579	416
Total available-for-sale, unrealized losses	(8)	(5)
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	65	99
Less than 12 months, unrealized losses	(1)	(1)
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	65	99
Total available-for-sale, unrealized losses	(1)	(1)
Foreign Government Debt [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	7	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	7	2
Total available-for-sale, unrealized losses	0	0
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	238	103
Less than 12 months, unrealized losses	(5)	(1)
12 months or longer, fair value	7	7
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	245	110
Total available-for-sale, unrealized losses	(5)	(1)
Residential Mortgage Backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	99	53
Less than 12 months, unrealized losses	(1)	(1)
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	99	53
Total available-for-sale, unrealized losses	(1)	(1)
Residential Mortgage Backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	5	2
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	1	1
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	6	3
Total available-for-sale, unrealized losses	0	0
Commercial Mortgage Backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	1	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	1	5
Total available-for-sale, unrealized losses	0	0
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	28	37
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	49	78
12 months or longer, unrealized losses	(1)	(2)
Total available-for-sale, fair value	77	115
Total available-for-sale, unrealized losses	(1)	(2)
Other Asset Backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	78	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	79	29
Total available-for-sale, unrealized losses	$ 0	$ 0