Post-Employment Benefits - Net Periodic Benefit Cost (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]
Service cost	$ 440	$ 370	$ 269
Interest cost	237	264	259
Expected return on plan assets	(663)	(575)	(474)
Amortization of prior service cost	2	2	0
Amortization of actuarial loss	(288)	(227)	(109)
Net periodic benefit cost	304	288	163
Other post-employment plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	48	42	25
Interest cost	19	34	29
Amortization of prior service cost	(39)	(4)	0
Amortization of actuarial loss	(32)	(26)	(1)
Net periodic benefit cost	$ 60	$ 98	$ 55