v3.10.0.1
Financial Instruments - Outstanding Fuel Hedges (Details) - Fuel Hedges Remaining 2018
Jun. 30, 2018
gal
$ / gal
Derivative [Line Items]  
Gallons Hedged (in gallons per year) | gal 3,750,000
Weighted Average Contract Price per Gallon (in dollars per gallon) | $ / gal 2.59