XML 141 R101.htm IDEA: XBRL DOCUMENT
v3.25.1

Financial Instruments and Risk Management (Fair Value And Presentation in the Balance Sheet Narrative) (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Collars and Forwards |  |
Disclosure of detailed information about financial instruments [line items] |  |
Financial liabilities, at fair value |  | $ 6.6
Derivatives | Currency Hedging Derivative Instruments |  |
Disclosure of detailed information about financial instruments [line items] |  |
Financial liabilities, at fair value | $ (9.0) |
Derivatives | Fuel Options |  |
Disclosure of detailed information about financial instruments [line items] |  |
Financial assets, at fair value | 0.1 | $ 0.2
Derivatives | Gold Options |  |
Disclosure of detailed information about financial instruments [line items] |  |
Financial assets, at fair value | $ (0.8) |

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfFinancialInstrumentsLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The fair value of financial assets. [Refer: At fair value [member]; Financial assets] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2024-01-01 -Paragraph 25 -URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2024-en-r&anchor=para_25&doctype=Standard -URIDate 2024-03-27 + Details
Name: | ifrs-full_FinancialAssetsAtFairValue
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The fair value of financial liabilities. [Refer: At fair value [member]; Financial liabilities] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2024-01-01 -Paragraph 25 -URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2024-en-r&anchor=para_25&doctype=Standard -URIDate 2024-03-27 + Details
Name: | ifrs-full_FinancialLiabilitiesAtFairValue
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | ifrs-full_HedgingInstrumentsAxis=agi_CollarsandForwardsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfFinancialAssetsAxis=ifrs-full_DerivativesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfFinancialInstrumentsAxis=agi_CurrencyHedgingDerivativeInstrumentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfFinancialInstrumentsAxis=agi_FuelOptionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfFinancialInstrumentsAxis=agi_GoldOptionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |