Pension Benefits Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Liability, Other Retirement Benefits	$ 1		$ 1		$ 1
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	$ 9	19	$ 17
Interest cost	9	9	18	17
Expected return on plan assets	(13)	(12)	(27)	(23)
Amortization of actuarial losses	6	7	12	13
Net periodic benefit cost	$ 11	$ 13	$ 22	$ 24