Reserves - Disclosure of Outstanding Share Purchase Options (Parenthetical) (Detail) $ in Millions |
3 Months Ended | 6 Months Ended | ||||
|---|---|---|---|---|---|---|
|
Mar. 31, 2026
$ / shares
|
Mar. 31, 2026
USD ($)
|
Mar. 31, 2025
$ / shares
|
Mar. 31, 2025
USD ($)
|
Jun. 30, 2026
$ / shares
|
Jun. 30, 2025
$ / shares
|
|
| Disclosure of terms and conditions of share-based payment arrangement [abstract] | ||||||
| Fair value per option granted | $ / shares | $ 43.34 | $ 23.9 | $ 43.34 | $ 23.9 | ||
| Fair value of options issued during the year | $ | $ 3 | $ 3 | ||||