Pension, Savings and Other Postretirement Benefit Plans - Defined Benefit Pension Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
U.S.
Defined Benefit Plan, Net Periodic Benefit Cost
Service cost	$ 1	$ 1	$ 3	$ 3
Interest cost	39	39	118	120
Expected return on plan assets	(55)	(60)	(164)	(181)
Amortization of net losses	28	27	84	83
Net periodic pension cost	13	7	41	25
Net curtailments/settlements/termination benefits	0	24	3	25
Total defined benefit pension cost	13	31	44	50
Non-U.S.
Defined Benefit Plan, Net Periodic Benefit Cost
Service cost	7	8	21	23
Interest cost	17	18	52	53
Expected return on plan assets	(17)	(20)	(53)	(59)
Amortization of net losses	7	8	22	24
Net periodic pension cost	14	14	42	41
Net curtailments/settlements/termination benefits	10	2	10	2
Total defined benefit pension cost	$ 24	$ 16	$ 52	$ 43