Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Available For Sale Securities [Abstract]
Investment, Type [Extensible Enumeration]	Fixed Maturities [Member]	Fixed Maturities [Member]
Less than 12 months, fair value	$ 107	$ 58
Less than 12 months, unrealized losses	(2)	(1)
12 months or longer, fair value	763	796
12 months or longer, unrealized losses	(152)	(139)
Total, fair value	870	854
Tota, unrealized losses	(154)	(140)
U.S. Treasury And Government Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	25	11
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	140	143
12 months or longer, unrealized losses	(20)	(18)
Total, fair value	165	154
Tota, unrealized losses	(20)	(18)
State and municipal bonds [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	27	23
Less than 12 months, unrealized losses	(1)	(1)
12 months or longer, fair value	58	57
12 months or longer, unrealized losses	(8)	(7)
Total, fair value	85	80
Tota, unrealized losses	(9)	(8)
Foreign Governments [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	6	6
12 months or longer, unrealized losses	(2)	(2)
Total, fair value	8	6
Tota, unrealized losses	(2)	(2)
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	25	17
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	334	337
12 months or longer, unrealized losses	(97)	(90)
Total, fair value	359	354
Tota, unrealized losses	(98)	(90)
Residential Mortgage backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	9	0
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	112	118
12 months or longer, unrealized losses	(17)	(14)
Total, fair value	121	118
Tota, unrealized losses	(17)	(14)
Residential Mortgage Backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	3	3
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	21	21
12 months or longer, unrealized losses	(6)	(5)
Total, fair value	24	24
Tota, unrealized losses	(6)	(5)
Commercial mortgage backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	0	4
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	3	3
12 months or longer, unrealized losses	0	0
Total, fair value	3	7
Tota, unrealized losses	0	0
Collateralized debt obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	0	0
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	72	89
12 months or longer, unrealized losses	(1)	(1)
Total, fair value	72	89
Tota, unrealized losses	(1)	(1)
Other asset backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	16	0
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	17	22
12 months or longer, unrealized losses	(1)	(2)
Total, fair value	33	22
Tota, unrealized losses	$ (1)	$ (2)