Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 1,726	$ 676
Less than 12 months, unrealized losses	(82)	(8)
12 months or longer, fair value	124	55
12 months or longer, unrealized losses	(11)	(1)
Total available-for-sale, fair value	1,850	731
Total available-for-sale, unrealized losses	(93)	(9)
U S Treasury And Government [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	239	161
Less than 12 months, unrealized losses	(13)	(1)
12 months or longer, fair value	20	16
12 months or longer, unrealized losses	(2)	(1)
Total available-for-sale, fair value	259	177
Total available-for-sale, unrealized losses	(15)	(2)
State and municipal bonds [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	486	11
Less than 12 months, unrealized losses	(20)	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	486	11
Total available-for-sale, unrealized losses	(20)	0
Foreign Government Debt [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	14	3
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	14	3
Total available-for-sale, unrealized losses	(1)	0
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	576	270
Less than 12 months, unrealized losses	(40)	(5)
12 months or longer, fair value	32	8
12 months or longer, unrealized losses	(4)	0
Total available-for-sale, fair value	608	278
Total available-for-sale, unrealized losses	(44)	(5)
Residential Mortgage Backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	113	94
Less than 12 months, unrealized losses	(4)	(1)
12 months or longer, fair value	37	1
12 months or longer, unrealized losses	(4)	0
Total available-for-sale, fair value	150	95
Total available-for-sale, unrealized losses	(8)	(1)
Residential Mortgage Backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	28	3
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	1	1
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	29	4
Total available-for-sale, unrealized losses	(1)	0
Commercial Mortgage Backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	9	2
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	9	2
Total available-for-sale, unrealized losses	(1)	0
Collateralized Debt Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	86	60
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	33	29
12 months or longer, unrealized losses	(1)	0
Total available-for-sale, fair value	119	89
Total available-for-sale, unrealized losses	(1)	0
Other Asset Backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	175	72
Less than 12 months, unrealized losses	(2)	(1)
12 months or longer, fair value	1	0
12 months or longer, unrealized losses	0	0
Total available-for-sale, fair value	176	72
Total available-for-sale, unrealized losses	$ (2)	$ (1)