Pension and Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 10	$ 13	$ 21	$ 26
Expected return on plan assets	(17)	(21)	(35)	(42)
Service cost
Amortization of net actuarial loss	7	6	14	12
Net periodic benefit cost (credit)	0	(2)	0	(4)
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	2	2	3	4
Expected return on plan assets		(1)	(1)	(2)
Service cost	2	2	4	3
Amortization of net actuarial loss	1	1	3	3
Net periodic benefit cost (credit)	5	4	9	8
Other Postretirement Benefits Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	1	2	2
Expected return on plan assets
Service cost
Amortization of net actuarial loss
Net periodic benefit cost (credit)	$ 1	$ 1	$ 2	$ 2