Postretirement Benefit Plans - Expense Related to Defined Benefit and Retiree Health Care Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5	$ 5	$ 9	$ 10
Interest cost	10	9	19	18
Expected return on plan assets	(12)	(10)	(21)	(21)
Recognized net actuarial loss	3	4	5	8
Amortization of prior service credit	0	0	0	0
Net periodic benefit costs	6	8	12	15
Settlement losses	3	0	6	2
Total, including other postretirement losses	9	8	18	17
U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	1	2
Interest cost	4	3	7	7
Expected return on plan assets	(3)	(3)	(7)	(7)
Recognized net actuarial loss	0	0	0	1
Amortization of prior service credit	0	0	0	(1)
Net periodic benefit costs	1	1	1	2
Settlement losses	0	0	0	0
Total, including other postretirement losses	$ 1	$ 1	$ 1	$ 2
Defined Benefit Plan, Sponsor Location [Extensible List]	country:US	country:US	country:US	country:US
Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8	$ 9	$ 16	$ 18
Interest cost	11	11	22	23
Expected return on plan assets	(23)	(17)	(44)	(34)
Recognized net actuarial loss	8	6	15	11
Amortization of prior service credit	0	(1)	0	(1)
Net periodic benefit costs	4	8	9	17
Settlement losses	1	1	2	1
Total, including other postretirement losses	$ 5	$ 9	$ 11	$ 18