Mexican Fuel Excise Tax Credit (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Mexican Fuel Excise Tax Credit [Line Items]
Benefit recognized by the Company relating to a Mexican fuel excise tax credit	$ 12.8	$ 34.0	$ 24.5	$ 34.0
Mexican Tax Authority [Member]
Mexican Fuel Excise Tax Credit [Line Items]
Benefit recognized by the Company relating to a Mexican fuel excise tax credit	$ 12.8	$ 34.0	$ 24.5