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Supplemental Disclosures about Oil and Natural Gas Producing Properties (unaudited) - Schedule of NYMEX Prices Used in Determining Future Cash Flows (Details) | 12 Months Ended
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Jun. 30, 2017 $ / bbl $ / MMBtu | Jun. 30, 2016 $ / bbl $ / MMBtu | Jun. 30, 2015 $ / bbl $ / MMBtu
Oil (per barrel) |  |  |
Average Sales Price and Production Costs Per Unit of Production [Line Items] |  |  |
Commodity Prices Used in Determining Future Cash Flows | $ / bbl | 48.85 | 42.91 | 71.88
Gas (per million BTU) |  |  |
Average Sales Price and Production Costs Per Unit of Production [Line Items] |  |  |
Commodity Prices Used in Determining Future Cash Flows | $ / MMBtu | 0 | 0 | 3.44

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