Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Available For Sale Securities [Abstract]
Investment, Type [Extensible Enumeration]	Fixed Maturities [Member]	Fixed Maturities [Member]
Less than 12 months, fair value	$ 58	$ 1,165
Less than 12 months, unrealized losses	(1)	(177)
12 months or longer, fair value	796	323
12 months or longer, unrealized losses	(139)	(66)
Total, fair value	854	1,488
Tota, unrealized losses	(140)	(243)
U.S. Treasury And Government Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	11	266
Less than 12 months, unrealized losses	0	(34)
12 months or longer, fair value	143	29
12 months or longer, unrealized losses	(18)	(4)
Total, fair value	154	295
Tota, unrealized losses	(18)	(38)
State and municipal bonds [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	23	92
Less than 12 months, unrealized losses	(1)	(10)
12 months or longer, fair value	57	1
12 months or longer, unrealized losses	(7)	(1)
Total, fair value	80	93
Tota, unrealized losses	(8)	(11)
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	0	9
Less than 12 months, unrealized losses	0	(3)
12 months or longer, fair value	6	0
12 months or longer, unrealized losses	(2)	0
Total, fair value	6	9
Tota, unrealized losses	(2)	(3)
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	17	508
Less than 12 months, unrealized losses	0	(106)
12 months or longer, fair value	337	141
12 months or longer, unrealized losses	(90)	(42)
Total, fair value	354	649
Tota, unrealized losses	(90)	(148)
Residential Mortgage backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	0	112
Less than 12 months, unrealized losses	0	(9)
12 months or longer, fair value	118	65
12 months or longer, unrealized losses	(14)	(13)
Total, fair value	118	177
Tota, unrealized losses	(14)	(22)
Residential Mortgage Backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	3	65
Less than 12 months, unrealized losses	0	(10)
12 months or longer, fair value	21	2
12 months or longer, unrealized losses	(5)	(1)
Total, fair value	24	67
Tota, unrealized losses	(5)	(11)
Commercial mortgage backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	4	18
Less than 12 months, unrealized losses	0	(1)
12 months or longer, fair value	3	1
12 months or longer, unrealized losses	0	0
Total, fair value	7	19
Tota, unrealized losses	0	(1)
Collateralized debt obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	0	51
Less than 12 months, unrealized losses	0	(1)
12 months or longer, fair value	89	60
12 months or longer, unrealized losses	(1)	(4)
Total, fair value	89	111
Tota, unrealized losses	(1)	(5)
Other asset backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	0	44
Less than 12 months, unrealized losses	0	(3)
12 months or longer, fair value	22	24
12 months or longer, unrealized losses	(2)	(1)
Total, fair value	22	68
Tota, unrealized losses	$ (2)	$ (4)