Employee Benefits - Change In Benefit Obligations Change In Plan Assets Funded Status (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension
Change in Benefit Obligations
Beginning of year	$ 15,133	$ 15,369
Service cost	185	208	$ 246
Interest cost	479	752	544
Plan amendments	0	0
Actuarial (gain) loss, net	(1,130)	5
Benefits paid	(419)	(1,008)
Curtailment and termination benefits	6	5
Settlements paid	(725)	(198)
Annuity contracts transfer	(5,611)	0
End of year	7,918	15,133	15,369
Change in Plan Assets
Beginning of year	13,536	13,739
Actual return on plan assets	(400)	751
Company contributions	421	252
Benefits paid	(419)	(1,008)
Settlements paid	(725)	(198)
Annuity contracts transfer	5,611	0
End of year	6,802	13,536	13,739
Funded Status
Funded Status - End of year	(1,116)	(1,597)
Health Care and Life
Change in Benefit Obligations
Beginning of year	11,455	11,107
Service cost	52	54	94
Interest cost	543	545	332
Plan amendments	0	(26)
Actuarial (gain) loss, net	(533)	757
Benefits paid	(978)	(982)
Curtailment and termination benefits	0	0
Settlements paid	0	0
Annuity contracts transfer	0	0
End of year	10,539	11,455	11,107
Change in Plan Assets
Beginning of year	466	450
Actual return on plan assets	43	62
Company contributions	935	936
Benefits paid	(978)	(982)
Settlements paid	0	0
Annuity contracts transfer	0	0
End of year	466	466	$ 450
Funded Status
Funded Status - End of year	$ (10,073)	$ (10,989)