Basis of preparation - Significant accounting judgements and estimates (Details) |
6 Months Ended | 12 Months Ended |
|---|---|---|
|
Jun. 30, 2026
$ / MMBTU
$ / bbl
|
Dec. 31, 2025
$ / bbl
$ / MMBTU
|
|
| Basis of preparation [Line Items] | ||
| Discount rate used in current estimate of value in use, after tax | 8.00% | 8.00% |
| Later than one year and not later than six years | ||
| Basis of preparation [Line Items] | ||
| Long-term price assumptions used in value-in-use impairment testing | $ / bbl | 80 | 70 |
| Not later than one year [member] | ||
| Basis of preparation [Line Items] | ||
| Long-term price assumptions used in value-in-use impairment testing | $ / MMBTU | 3.34 | 3.80 |