Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 348	$ 1,165
Less than 12 months, unrealized losses	(12)	(177)
12 months or longer, fair value	1,054	323
12 months or longer, unrealized losses	(245)	(66)
Total, fair value	1,402	1,488
Tota, unrealized losses	(257)	(243)
U.S. Treasury and government agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	64	266
Less than 12 months, unrealized losses	(3)	(34)
12 months or longer, fair value	196	29
12 months or longer, unrealized losses	(38)	(4)
Total, fair value	260	295
Tota, unrealized losses	(41)	(38)
State and municipal bonds [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	48	92
Less than 12 months, unrealized losses	(3)	(10)
12 months or longer, fair value	54	1
12 months or longer, unrealized losses	(12)	(1)
Total, fair value	102	93
Tota, unrealized losses	(15)	(11)
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	5	9
Less than 12 months, unrealized losses	0	(3)
12 months or longer, fair value	8	0
12 months or longer, unrealized losses	(4)	0
Total, fair value	13	9
Tota, unrealized losses	(4)	(3)
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	192	508
Less than 12 months, unrealized losses	(5)	(106)
12 months or longer, fair value	500	141
12 months or longer, unrealized losses	(153)	(42)
Total, fair value	692	649
Tota, unrealized losses	(158)	(148)
Residential Mortgage backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	13	112
Less than 12 months, unrealized losses	0	(9)
12 months or longer, fair value	132	65
12 months or longer, unrealized losses	(26)	(13)
Total, fair value	145	177
Tota, unrealized losses	(26)	(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	22	2
12 months or longer, unrealized losses	(7)	(1)
Total, fair value	25	67
Tota, unrealized losses	(7)	(11)
Commercial mortgage backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	11	18
Less than 12 months, unrealized losses	(1)	(1)
12 months or longer, fair value	7	1
12 months or longer, unrealized losses	0	0
Total, fair value	18	19
Tota, unrealized losses	(1)	(1)
Collateralized debt obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	9	51
Less than 12 months, unrealized losses	0	(1)
12 months or longer, fair value	101	60
12 months or longer, unrealized losses	(2)	(4)
Total, fair value	110	111
Tota, unrealized losses	(2)	(5)
Other asset backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	3	44
Less than 12 months, unrealized losses	0	(3)
12 months or longer, fair value	34	24
12 months or longer, unrealized losses	(3)	(1)
Total, fair value	37	68
Tota, unrealized losses	$ (3)	$ (4)