Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Available For Sale Securities [Abstract]
Investment, Type [Extensible Enumeration]	Fixed Maturities [Member]	Fixed Maturities [Member]
Less than 12 months, fair value	$ 329	$ 53
Less than 12 months, unrealized losses	(5)	(2)
12 months or longer, fair value	491	593
12 months or longer, unrealized losses	(164)	(127)
Total, fair value	820	646
Tota, unrealized losses	(169)	(129)
U.S. Treasury And Government Agency [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	21	2
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	92	122
12 months or longer, unrealized losses	(14)	(10)
Total, fair value	113	124
Tota, unrealized losses	(15)	(10)
State and municipal bonds [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	19	4
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	51	63
12 months or longer, unrealized losses	(13)	(8)
Total, fair value	70	67
Tota, unrealized losses	(14)	(8)
Foreign Governments [Member] \| Fixed Maturities [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	5	5
12 months or longer, unrealized losses	(3)	(2)
Total, fair value	5	5
Tota, unrealized losses	(3)	(2)
Corporate Obligations [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	89	9
Less than 12 months, unrealized losses	(1)	(2)
12 months or longer, fair value	253	283
12 months or longer, unrealized losses	(116)	(94)
Total, fair value	342	292
Tota, unrealized losses	(117)	(96)
Residential Mortgage backed Agency [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	18	5
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	75	90
12 months or longer, unrealized losses	(15)	(11)
Total, fair value	93	95
Tota, unrealized losses	(16)	(11)
Residential Mortgage Backed Non Agency [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	9	5
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	4	5
12 months or longer, unrealized losses	(1)	(1)
Total, fair value	13	10
Tota, unrealized losses	(1)	(1)
Commercial mortgage backed Securities [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value		0
Less than 12 months, unrealized losses		0
12 months or longer, fair value		3
12 months or longer, unrealized losses		0
Total, fair value		3
Tota, unrealized losses		0
Collateralized debt obligations [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	52	8
Less than 12 months, unrealized losses	0	0
12 months or longer, fair value	0	0
12 months or longer, unrealized losses	0	0
Total, fair value	52	8
Tota, unrealized losses	0	0
Other asset backed [Member] \| Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Less than 12 months, fair value	121	20
Less than 12 months, unrealized losses	(1)	0
12 months or longer, fair value	11	22
12 months or longer, unrealized losses	(2)	(1)
Total, fair value	132	42
Tota, unrealized losses	$ (3)	$ (1)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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