Postretirement Benefit Plans - Expense Related to Defined Benefit and Retiree Health Care Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5	$ 5	$ 16	$ 16
Interest cost	11	10	32	32
Expected return on plan assets	(11)	(10)	(31)	(31)
Recognized net actuarial loss	4	5	11	15
Amortization of prior service credit	0	0	0	0
Net periodic benefit costs	9	10	28	32
Settlement losses	13	4	23	17
Total, including other postretirement losses	22	14	51	49
U.S. | Retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	1	4	4
Interest cost	4	5	13	15
Expected return on plan assets	(4)	(4)	(13)	(14)
Recognized net actuarial loss	0	2	2	5
Amortization of prior service credit	(1)	(1)	(3)	(3)
Net periodic benefit costs	1	3	3	7
Settlement losses	0	0	0	0
Total, including other postretirement losses	1	3	3	7
Non-U.S. | Defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	9	27	25
Interest cost	11	14	33	40
Expected return on plan assets	(16)	(18)	(47)	(52)
Recognized net actuarial loss	7	6	21	19
Amortization of prior service credit	0	0	(1)	(1)
Net periodic benefit costs	11	11	33	31
Settlement losses	1	0	2	1
Total, including other postretirement losses	$ 12	$ 11	$ 35	$ 32