Employee Benefits - Change In Benefit Obligations Change In Plan Assets Funded Status (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension
Change in Benefit Obligations
Beginning of year	$ 20,167	$ 22,236
Service cost	246	282	$ 305
Interest cost	544	394	505
Plan amendments	427	0
Actuarial gain, net	(3,865)	(605)
Benefits paid	(782)	(816)
Curtailment and termination benefits	2	6
Settlements paid	(1,370)	(1,330)
End of year	15,369	20,167	22,236
Change in Plan Assets
Beginning of year	20,087	20,128
Actual return on plan assets	(4,249)	2,049
Company contributions	53	56
Benefits paid	(782)	(816)
Settlements paid	(1,370)	(1,330)
End of year	13,739	20,087	20,128
Funded Status
Funded Status - End of year	(1,630)	(80)
Health Care and Life
Change in Benefit Obligations
Beginning of year	14,710	16,168
Service cost	94	112	110
Interest cost	332	289	429
Plan amendments	4	0
Actuarial gain, net	(3,297)	(930)
Benefits paid	(736)	(929)
Curtailment and termination benefits	0	0
Settlements paid	0	0
End of year	11,107	14,710	16,168
Change in Plan Assets
Beginning of year	581	572
Actual return on plan assets	(87)	53
Company contributions	692	885
Benefits paid	(736)	(929)
Settlements paid	0	0
End of year	450	581	$ 572
Funded Status
Funded Status - End of year	$ (10,657)	$ (14,129)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

Name:	us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.