Post-Employment Benefits - Pretax Gains and Losses Included in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined benefit plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actuarial loss	$ (345)	$ 701	$ 1,231
Amortization of prior service credit (cost)	(2)	(2)	0
Amortization of actuarial loss	(288)	(227)	(109)
Foreign exchange loss (gain) and other	(27)	56	(6)
Total loss (gain)	(662)	528	1,116
Other post-employment plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actuarial loss	10	40	451
Amortization of prior service credit (cost)	39	4	0
Amortization of actuarial loss	(32)	(26)	(1)
Prior service credit	0	(397)	0
Total loss (gain)	$ 17	$ (379)	$ 450