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Commodity Derivative Instruments (Schedule of Gain (Loss) Recognized in Statements of Operations) (Details) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
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Feb. 28, 2014
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Feb. 28, 2013
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Feb. 28, 2014
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Feb. 28, 2013
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| Commodity Derivative Instruments [Abstract] | ||||
| Realized gain (loss) on commodity derivatives | $ (191) | $ (20) | $ (589) | $ (20) |
| Unrealized gain (loss) on commodity derivatives | (1,805) | (134) | 831 | (134) |
| Total gain (loss) | $ (1,996) | $ (154) | $ 242 | $ (154) |