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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
U.S. defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6	$ 5	$ 11	$ 11
Interest cost	11	11	22	21
Expected return on plan assets	(11)	(12)	(21)	(24)
Recognized net actuarial loss	5	5	10	10
Amortization of prior service cost (credit)	0	0	0	0
Net periodic benefit costs	11	9	22	18
Settlement losses	7	11	13	12
Total	18	20	35	30
U.S. retiree health care plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	3	3
Interest cost	5	5	10	10
Expected return on plan assets	(5)	(6)	(10)	(11)
Recognized net actuarial loss	1	2	3	4
Amortization of prior service cost (credit)	(1)	2	(2)	3
Net periodic benefit costs	2	5	4	9
Settlement losses	0	0	0	0
Total	2	5	4	9
Non-U.S. defined benefit plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	8	8	16	17
Interest cost	13	14	26	27
Expected return on plan assets	(17)	(19)	(34)	(38)
Recognized net actuarial loss	7	6	13	12
Amortization of prior service cost (credit)	(1)	(1)	(1)	(1)
Net periodic benefit costs	10	8	20	17
Settlement losses	0	2	1	2
Total	$ 10	$ 10	$ 21	$ 19