Pensions and Other Postretirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Non-service cost components of net periodic pension and OPEB income	$ 322	$ 125	$ 996	$ 587
Global OPEB Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost	5	4	14	12
Interest cost	43	54	130	163
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	(1)	(3)	(5)	(10)
Amortization of net actuarial losses	18	7	55	22
Curtailments, settlements and other	0	0	0	0
Net periodic pension and OPEB (income) expense	65	62	194	187
U.S. [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost	63	99	188	295
Interest cost	429	566	1,287	1,698
Expected return on plan assets	(816)	(871)	(2,449)	(2,610)
Amortization of prior service cost (credit)	(1)	(1)	(3)	(3)
Amortization of net actuarial losses	4	2	12	8
Curtailments, settlements and other	0	0	0	0
Net periodic pension and OPEB (income) expense	(321)	(205)	(965)	(612)
Non-U.S. [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service cost	41	38	107	102
Interest cost	92	148	271	386
Expected return on plan assets	(174)	(240)	(507)	(627)
Amortization of prior service cost (credit)	2	2	5	4
Amortization of net actuarial losses	44	31	126	90
Curtailments, settlements and other	15	119	15	119
Net periodic pension and OPEB (income) expense	$ 20	$ 98	$ 17	$ 74