Accumulated Other Comprehensive Earnings (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 24, 2022	Sep. 30, 2023	Sep. 24, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances at Beginning of Period	$ (576)	$ (555)	$ (609)	$ (5)
Unrealized gain (loss) on debt securities	(37)	(119)	(4)	(669)
Net realized gain on debt securities reclassified to investment income	0	2	0	1
Adjustment to postretirement benefit obligation income taxes	0	0	0	1
Net other comprehensive losses	(37)	(117)	(4)	(667)
Balances at End of Period	(613)	(672)	(613)	(672)
Investments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances at Beginning of Period	(585)	(544)	(618)	7
Unrealized gain (loss) on debt securities	(37)	(119)	(4)	(669)
Net realized gain on debt securities reclassified to investment income	0	2	0	1
Net other comprehensive losses	(37)	(117)	(4)	(668)
Balances at End of Period	(622)	(661)	(622)	(661)
Postretirement Benefit Obligation [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balances at Beginning of Period	9	(11)	9	(12)
Adjustment to postretirement benefit obligation income taxes	0	0	0	1
Net other comprehensive losses	0	0	0	1
Balances at End of Period	$ 9	$ (11)	$ 9	$ (11)