Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 539	$ 325
Less than 12 months, unrealized losses	(7)	(3)
12 months or longer, fair value	62	91
12 months or longer, unrealized losses	(2)	(2)
Total available-for-sale, fair value	601	416
Total available-for-sale, unrealized losses	(9)	(5)
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	60	99
Less than 12 months, unrealized losses	(1)	(1)
12 months or longer, fair value	10	0
12 months or longer, unrealized losses	(1)	0
Total available-for-sale, fair value	70	99
Total available-for-sale, unrealized losses	(2)	(1)
State and municipal bonds [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	1
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	1
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	287	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	294	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	83	53
Less than 12 months, unrealized losses	(1)	(1)
12 months or longer, fair value	1	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	84	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	0	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	1	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	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	44	37
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	43	78
12 months or longer, unrealized losses	(1)	(2)
Total available-for-sale, fair value	87	115
Total available-for-sale, unrealized losses	(1)	(2)
Other Asset Backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	56	29
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	56	29
Total available-for-sale, unrealized losses	$ 0	$ 0