Derivatives (Narrative) (Details) gal in Millions	3 Months Ended
Mar. 31, 2017 gal
Diesel swap
Derivative [Line Items]
Fixed price swap contract (in gallons)	6.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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