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Summary of Significant Accounting Policies (Details)
 12 Months Ended
Jun. 30, 2018
USD ($)
Jun. 30, 2017
USD ($)
Accounting Policies [Abstract]    
Allowance for doubtful accounts $ 0 $ 0
Oil and natural gas properties    
Limitation on Capitalized Costs    
Period considered for computing unweighted arithmetic average of oil and natural gas prices (in months) 12 months  
Other Property and Equipment | Minimum    
Other Property and Equipment    
Expected lives of the individual assets or group of assets 3 years  
Other Property and Equipment | Maximum    
Other Property and Equipment    
Expected lives of the individual assets or group of assets 7 years  
Discount rate | Oil and natural gas properties    
Limitation on Capitalized Costs    
Discount rate for present value (as a percent) 0.10