XML 62 R31.htm IDEA: XBRL DOCUMENT
v3.23.1

Inventory (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2022
Disclosure of inventories [Abstract] |
Schedule of Inventory |
| December 31, 2022 | December 31, 2021
In-process precious metals | $159.4 |  | $116.2 |
Ore in stockpiles | 10.0 |  | 25.4 |
Parts and supplies | 57.2 |  | 61.0 |
Dore, and refined precious metals | 7.6 |  | 7.0 |
| 234.2 |  | 209.6 |
Less: Long-term inventory | — |  | (10.6) |
| $234.2 |  | $199.0 |

X
- Definition Disclosure of inventories [Abstract] + References No definition available. + Details
Name: | agi_DisclosureofinventoriesAbstract
Namespace Prefix: | agi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule of Inventory + References No definition available. + Details
Name: | agi_ScheduleofInventoryTableTextBlock
Namespace Prefix: | agi_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration