Other Income and Expense - Other Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Schedule of other expense [Line Items]
Gain (Loss) on Disposition of Assets	$ (7)	$ (2)
Other Expenses	12	9
Other Expense [Member]
Schedule of other expense [Line Items]
Gain (Loss) on Disposition of Assets	5	2
Defined Benefit Plan, Other Cost (Credit)	4	5
Other Nonoperating Expense	3	2
Other Expenses	$ 12	$ 9