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Concentrations of Credit Risk - Schedule of Credit Risk (Details) - Net revenue - Major Customers	12 Months Ended
	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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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.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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