Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Available For Sale Securities [Abstract]
Less than 12 months, fair value	$ 644	$ 1,165
Less than 12 months, unrealized losses	(59)	(177)
12 months or longer, fair value	845	323
12 months or longer, unrealized losses	(145)	(66)
Total, fair value	1,489	1,488
Tota, unrealized losses	(204)	(243)
U.S. Treasury and government agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	131	266
Less than 12 months, unrealized losses	(9)	(34)
12 months or longer, fair value	152	29
12 months or longer, unrealized losses	(18)	(4)
Total, fair value	283	295
Tota, unrealized losses	(27)	(38)
State and municipal bonds [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	47	92
Less than 12 months, unrealized losses	(1)	(10)
12 months or longer, fair value	28	1
12 months or longer, unrealized losses	(7)	(1)
Total, fair value	75	93
Tota, unrealized losses	(8)	(11)
Foreign Governments [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	1	9
Less than 12 months, unrealized losses	0	(3)
12 months or longer, fair value	9	0
12 months or longer, unrealized losses	(2)	0
Total, fair value	10	9
Tota, unrealized losses	(2)	(3)
Corporate Obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	301	508
Less than 12 months, unrealized losses	(40)	(106)
12 months or longer, fair value	390	141
12 months or longer, unrealized losses	(89)	(42)
Total, fair value	691	649
Tota, unrealized losses	(129)	(148)
Residential Mortgage backed Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	60	112
Less than 12 months, unrealized losses	(3)	(9)
12 months or longer, fair value	114	65
12 months or longer, unrealized losses	(17)	(13)
Total, fair value	174	177
Tota, unrealized losses	(20)	(22)
Residential Mortgage backed Non Agency [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	51	65
Less than 12 months, unrealized losses	(5)	(10)
12 months or longer, fair value	23	2
12 months or longer, unrealized losses	(5)	(1)
Total, fair value	74	67
Tota, unrealized losses	(10)	(11)
Commercial mortgage backed Securities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	19	18
Less than 12 months, unrealized losses	0	(1)
12 months or longer, fair value	7	1
12 months or longer, unrealized losses	(1)	0
Total, fair value	26	19
Tota, unrealized losses	(1)	(1)
Collateralized debt obligations [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	25	51
Less than 12 months, unrealized losses	(1)	(1)
12 months or longer, fair value	85	60
12 months or longer, unrealized losses	(3)	(4)
Total, fair value	110	111
Tota, unrealized losses	(4)	(5)
Other asset backed [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	9	44
Less than 12 months, unrealized losses	0	(3)
12 months or longer, fair value	37	24
12 months or longer, unrealized losses	(3)	(1)
Total, fair value	46	68
Tota, unrealized losses	$ (3)	$ (4)