Pension and Other Postretirement Benefit Plans - Net Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8	$ 8
Interest cost	14	16
Expected return on plan assets	(20)	(16)
Amortization of unrecognized prior service credit	(11)	(12)
Net loss (gain) amortization	(12)	(11)
Net periodic benefit cost	(21)	(15)
U.S. | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	86	76
Interest cost	134	133
Expected return on plan assets	(207)	(187)
Amortization of unrecognized prior service credit	0	0
Net loss (gain) amortization	10	0
Termination benefits	3	0
Curtailments	0	2
Settlements	0	21
Net periodic benefit cost	26	45
International | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	61	49
Interest cost	74	74
Expected return on plan assets	(139)	(128)
Amortization of unrecognized prior service credit	(3)	(3)
Net loss (gain) amortization	1	(1)
Termination benefits	0	0
Curtailments	0	0
Settlements	0	0
Net periodic benefit cost	$ (6)	$ (9)