Other Income and Expense - Other Expense (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule of other expense [Line Items]
Gain (Loss) on Disposition of Assets				$ (21)	$ (23)
Other Expenses		$ 9	$ 29	35	42
Other Expense [Member]
Schedule of other expense [Line Items]
Gain (Loss) on Disposition of Assets	[1]	5	20	19	25
Defined Benefit Plan, Other Cost (Credit)		4	1	13	7
Other Nonoperating Expense		0	8	3	10
Other Expenses		$ 9	$ 29	$ 35	$ 42

[1] ⁽²⁾  Associated with a loss due to damage from a lightning incident at the Andres facility in the Dominican Republic in September 2018 and the disposal of tunnel lining at Changuinola in 2019.