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Movement in Capitalised Exploratory Well Costs (Detail) - USD ($)
$ in Millions
 12 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2019
Extractive Industries [Abstract]      
At the beginning of the year $ 1,089 $ 1,040 $ 794
Additions to capitalised exploratory well costs pending the determination of proved reserves 7 120 297
Capitalised exploratory well costs charged to expense (66)   (9)
Capitalised exploratory well costs reclassified to wells, equipment, and facilities based on the determination of proved reserves   (6) (42)
Sale of suspended wells   (65)  
At the end of the year $ 1,030 $ 1,089 $ 1,040