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Concentrations of Credit Risk - Schedule of Credit Risk (Details) - Net revenue - Major Customers | 12 Months Ended
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Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2016
Concentrations of Credit Risk |  |  |
Percent of Total Revenue | 100.00% | 100.00% | 100.00%
Plains Marketing L.P. (Oil sales from Delhi) |  |  |
Concentrations of Credit Risk |  |  |
Percent of Total Revenue | 92.00% | 97.00% | 99.00%
American Midstream Gas Solutions (NGL sales from Delhi) |  |  |
Concentrations of Credit Risk |  |  |
Percent of Total Revenue | 8.00% | 3.00% | 0.00%
All others |  |  |
Concentrations of Credit Risk |  |  |
Percent of Total Revenue | 0.00% | 0.00% | 1.00%

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