v3.19.3.a.u2
Post-Employment Benefits - Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Defined benefit plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Service cost $ 269 $ 285 $ 236
Interest cost 259 227 204
Expected return on plan assets (474) (439) (382)
Amortization of actuarial loss and prior service credit 109 140 107
Net periodic benefit cost 163 213 165
Other post-employment plans      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Service cost 25 26 26
Interest cost 29 25 24
Amortization of actuarial loss and prior service credit 1 1 0
Net periodic benefit cost $ 55 $ 52 $ 50