Pension Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
U.S. Pension Plans
Components of net periodic pension cost
Service cost	$ 4	$ 4
Interest cost	15	20
Expected asset return	(25)	(33)
Amortization:
Actuarial loss	13	14
Net periodic pension cost	7	5
Non-U.S. Pension Plans
Components of net periodic pension cost
Service cost	4	4
Interest cost	8	11
Expected asset return	(13)	(18)
Amortization:
Actuarial loss	4	5
Net periodic pension cost	$ 3	$ 2