Post-Employment Benefits - (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plans
Defined benefit plan net periodic benefit cost
Service cost - benefits earned during the period	$ 85	$ 64
Interest cost on projected benefit obligations	75	84
Expected return on plans assets	(192)	(178)
Net amortization of:
Actuarial loss, net	63	33
Net cost - continuing operations	31	3
Post-employment Obligations and Other Long-term Liabilities:
Company contributions	320	313
Medical and Dental Plans
Defined benefit plan net periodic benefit cost
Service cost - benefits earned during the period	12	6
Interest cost on projected benefit obligations	12	13
Expected return on plans assets	(7)	(7)
Net amortization of:
Actuarial loss, net	8	6
Prior service cost (credit)	(7)	(8)
Net cost - continuing operations	18	10
Post-employment Obligations and Other Long-term Liabilities:
Company contributions	$ 11	$ 11