Pension, Other Postretirement Benefits and Savings Plans - Benefit Costs and Amounts Recognized in Other Comprehensive (Income) Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Postretirement Benefits
Benefits cost (credit):
Service cost	$ 3	$ 4	$ 3
Interest cost	12	13	12
Expected return on plan assets	0	(1)	0
Amortization of prior service credit	(8)	(29)	(45)
Amortization of net losses	4	6	5
Net periodic cost (credit)	11	(7)	(25)
Net curtailments/settlements/termination benefits	0	0	2
Total benefits cost (credit)	11	(7)	(23)
Recognized in other comprehensive (income) loss before tax and minority:
Prior service cost (credit) from plan amendments	(16)	3	0
Increase (decrease) in net actuarial losses	(14)	(15)	(1)
Amortization of prior service credit in net periodic cost	8	29	45
Amortization of net losses in net periodic cost	(5)	(6)	(5)
Immediate recognition of prior service cost and unrecognized gains and losses due to curtailments, settlements, and divestitures	0	0	0
Total recognized in other comprehensive (income) loss before tax and minority	(27)	11	39
Total recognized in total benefits cost (credit) and other comprehensive (income) loss before tax and minority	(16)	4	16
United States | Pension Plan
Benefits cost (credit):
Service cost	4	4	5
Interest cost	157	160	164
Expected return on plan assets	(219)	(241)	(255)
Amortization of prior service credit	0	0	0
Amortization of net losses	112	111	109
Net periodic cost (credit)	54	34	23
Net curtailments/settlements/termination benefits	8	29	0
Total benefits cost (credit)	62	63	23
Recognized in other comprehensive (income) loss before tax and minority:
Prior service cost (credit) from plan amendments	0	0	0
Increase (decrease) in net actuarial losses	14	128	81
Amortization of prior service credit in net periodic cost	0	0	0
Amortization of net losses in net periodic cost	(112)	(111)	(109)
Immediate recognition of prior service cost and unrecognized gains and losses due to curtailments, settlements, and divestitures	(11)	(29)	0
Total recognized in other comprehensive (income) loss before tax and minority	(109)	(12)	(28)
Total recognized in total benefits cost (credit) and other comprehensive (income) loss before tax and minority	(47)	51	(5)
United States | Other Postretirement Benefits
Benefits cost (credit):
Total benefits cost (credit)	4	(17)	(31)
Non-U.S. | Pension Plan
Benefits cost (credit):
Service cost	28	31	29
Interest cost	69	71	80
Expected return on plan assets	(70)	(80)	(88)
Amortization of prior service credit	0	0	0
Amortization of net losses	29	32	27
Net periodic cost (credit)	56	54	48
Net curtailments/settlements/termination benefits	13	3	16
Total benefits cost (credit)	69	57	64
Recognized in other comprehensive (income) loss before tax and minority:
Prior service cost (credit) from plan amendments	31	3	0
Increase (decrease) in net actuarial losses	(18)	25	35
Amortization of prior service credit in net periodic cost	0	0	0
Amortization of net losses in net periodic cost	(30)	(29)	(27)
Immediate recognition of prior service cost and unrecognized gains and losses due to curtailments, settlements, and divestitures	(14)	(12)	(17)
Total recognized in other comprehensive (income) loss before tax and minority	(31)	(13)	(9)
Total recognized in total benefits cost (credit) and other comprehensive (income) loss before tax and minority	38	44	55
Non-U.S. | Other Postretirement Benefits
Benefits cost (credit):
Total benefits cost (credit)	$ 7	$ 10	$ 8