Employee Benefits - Benefit (Income) Cost Related to Pension and Postretirement Health Care and Life Insurance Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Remeasurement loss (gain), net	$ (1,700)	$ (2,400)	$ (1,600)
Other components	(2,386)	(3,785)	425
Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	246	282	305
Amortization of prior service cost (credit)	82	61	61
Expected return on plan assets	(1,119)	(1,234)	(1,186)
Interest cost	544	394	505
Remeasurement loss (gain), net	1,505	(1,419)	744
Curtailment and termination benefits	2	0	0
Other components	1,014	(2,198)	124
Total	1,260	(1,916)	429
Health Care and Life
Defined Benefit Plan Disclosure [Line Items]
Service cost	94	112	110
Amortization of prior service cost (credit)	(530)	(894)	(966)
Expected return on plan assets	(27)	(22)	(28)
Interest cost	332	289	429
Remeasurement loss (gain), net	(3,182)	(960)	866
Curtailment and termination benefits	0	0	0
Other components	(3,407)	(1,587)	301
Total	(3,313)	(1,475)	411
Cost of services | Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	216	247	245
Cost of services | Health Care and Life
Defined Benefit Plan Disclosure [Line Items]
Service cost	79	94	89
Selling, general and administrative expense | Pension
Defined Benefit Plan Disclosure [Line Items]
Service cost	30	35	60
Selling, general and administrative expense | Health Care and Life
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 15	$ 18	$ 21