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Derivative Instruments Outstanding Trading Contracts (Details) - Jun. 30, 2015 - Forward Contracts [Member] gal in Thousands | $ / gal gal
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Sales [Member] |
Derivative [Line Items] |
Quantity In Gallons | gal | 4,620
Weighted Average Contract Prices | 0.4760
Sales [Member] | Minimum [Member] |
Derivative [Line Items] |
Estimated Market Prices | 0.3475
Sales [Member] | Maximum [Member] |
Derivative [Line Items] |
Estimated Market Prices | 0.5288
Purchase [Member] |
Derivative [Line Items] |
Quantity In Gallons | gal | 4,620
Weighted Average Contract Prices | 0.4322
Purchase [Member] | Minimum [Member] |
Derivative [Line Items] |
Estimated Market Prices | 0.3550
Purchase [Member] | Maximum [Member] |
Derivative [Line Items] |
Estimated Market Prices | 0.5025

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