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Closure and Rehabilitation Provisions - Additional Information (Detail) - Closure and rehabilitation provisions [Member] - USD ($)
$ in Millions
 12 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2016
Disclosure of other provisions [Line Items]      
Increases to existing and new provisions associated closure and remediation costs charged to the income statement $ 132 $ 127  
Percentage of reasonably possible decrease in real discount rates 0.50%    
Increase in closure and rehabilitation provision due to reasonably possible decrease in real discount rates $ 604    
Increase in depreciation expense due to reasonably possible decrease in real discount rates $ 46    
Bottom of range [Member]      
Disclosure of other provisions [Line Items]      
Remaining production life 2 years    
Top of range [Member]      
Disclosure of other provisions [Line Items]      
Remaining production life 127 years    
Weighted average [Member]      
Disclosure of other provisions [Line Items]      
Remaining production life 29 years    
Closed sites [Member]      
Disclosure of other provisions [Line Items]      
Increases to existing and new provisions associated closure and remediation costs charged to the income statement $ (21) $ 33 $ 18
Increase in income statement charge due to reasonably possible decrease in real discount rates 80    
Operating sites [Member]      
Disclosure of other provisions [Line Items]      
Increase in property, plant and equipment due to reasonably possible decrease in real discount rates $ 524