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Number of Crude Oil and Natural Gas Wells Drilled and Completed (Detail) - Wells
 12 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2019
Disclosure of net productive wells and dry wells drilled [line items]      
Net exploratory wells, Productive   1 5
Net exploratory wells, Dry 1 1 2
Net exploratory wells, Total 1 2 7
Net development wells, Productive 3 1 34
Net development wells, Dry   1  
Net development wells, Total 3 2 34
Total 4 4 41
Australia [member]      
Disclosure of net productive wells and dry wells drilled [line items]      
Net development wells, Productive 1   1
Net development wells, Total 1   1
Total 1   1
United States [member]      
Disclosure of net productive wells and dry wells drilled [line items]      
Net exploratory wells, Productive     1
Net exploratory wells, Total     1
Net development wells, Productive 1   33
Net development wells, Dry   1  
Net development wells, Total 1 1 33
Total 1 1 34
Other countries [member]      
Disclosure of net productive wells and dry wells drilled [line items]      
Net exploratory wells, Productive   1 4
Net exploratory wells, Dry 1 1 2
Net exploratory wells, Total 1 2 6
Net development wells, Productive 1 1  
Net development wells, Total 1 1  
Total 2 3 6