Ageing of Capitalised Exploratory Well Costs (Detail) $ in Millions |
Jun. 30, 2021
USD ($)
Project
|
Jun. 30, 2020
USD ($)
Project
|
Jun. 30, 2019
USD ($)
Project
|
Jun. 30, 2018
USD ($)
|
|---|---|---|---|---|
| Extractive Industries [Abstract] | ||||
| Exploratory well costs capitalised for a period of one year or less | $ 7 | $ 120 | $ 210 | |
| Exploratory well costs capitalised for a period greater than one year | 1,023 | 969 | 830 | |
| At the end of the year | $ 1,030 | $ 1,089 | $ 1,040 | $ 794 |
| Number of projects that have been capitalised for a period greater than one year | Project | 15 | 14 | 13 |