Pension and Other Postretirement Benefit Plans - Components of Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain) amortization included in benefit cost	$ 144	$ 198	$ 112
Prior service (cost) credit arising during the period	(17)	(3)	(11)
Total	127	195	101
Net loss (gain) amortization included in benefit cost	(42)	(18)	(10)
Prior service credit amortization included in benefit cost	(63)	(73)	(78)
Total	(105)	(91)	(88)
United States | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain) amortization included in benefit cost	1,048	(448)	(816)
Prior service (cost) credit arising during the period	(3)	(1)	(4)
Total	1,045	(449)	(820)
Net loss (gain) amortization included in benefit cost	298	303	151
Prior service credit amortization included in benefit cost	(38)	(49)	(49)
Total	260	254	102
International | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain) amortization included in benefit cost	815	(407)	(227)
Prior service (cost) credit arising during the period	(29)	62	(1)
Total	786	(345)	(228)
Net loss (gain) amortization included in benefit cost	142	127	64
Prior service credit amortization included in benefit cost	(16)	(18)	(12)
Total	$ 126	$ 109	$ 52