XML 104 R73.htm IDEA: XBRL DOCUMENT
v3.23.1

Sale of Esperanza Project (Details) oz in Thousands, $ in Millions |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Apr. 12, 2022 USD ($) oz | Feb. 28, 2022 USD ($) | Dec. 31, 2022 USD ($) | Mar. 31, 2022 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
Disclosure of detailed information about investment property [Line Items] |  |  |  |  |  |  |
Cash and cash equivalents |  |  | $ 129.8 |  | $ 129.8 | $ 172.5 | $ 220.5
Impairment charge (note 14) |  |  |  |  | 38.2 | 224.3 |
Esperanza Milestone Payments (i) |  |  |  |  |  | 0.0 |
Milestone payment | $ 39.0 |  |  |  |  |  |
Impairment loss (reversal of impairment loss) recognised in profit or loss, after tax |  |  |  | $ 26.7 |  |  |
Consideration to be received, value |  |  |  |  | 23.0 |  |
Unrealized gain on non-hedging derivatives |  |  |  |  | $ (0.3) | $ 0.4 |
Metalla |  |  |  |  |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |  |  |  |  |
Consideration received |  |  | $ 5.0 |  |  |  |
Transaction Costs |  |  |  |  |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |  |  |  |  |
Impairment charge (note 14) |  |  |  | $ 0.2 |  |  |
Milestone One |  |  |  |  |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |  |  |  |  |
Milestone payment | $ 5.0 |  |  |  |  |  |
Number of days to receive milestone payment | 60 days |  |  |  |  |  |
Milestone Two |  |  |  |  |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |  |  |  |  |
Milestone payment | $ 14.0 |  |  |  |  |  |
Number of days to receive milestone payment | 60 days |  |  |  |  |  |
Milestone Three |  |  |  |  |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |  |  |  |  |
Milestone payment | $ 20.0 |  |  |  |  |  |
Number of days to receive milestone payment | 180 days |  |  |  |  |  |
Discontinued operations | Esperanza Project |  |  |  |  |  |  |
Disclosure of detailed information about investment property [Line Items] |  |  |  |  |  |  |
Proceeds from disposal of non-current assets or disposal groups classified as held for sale and discontinued operations | $ 21.0 | $ 60.0 |  |  |  |  |
Cash and cash equivalents | 5.0 |  |  |  |  |  |
Shares value | $ 10.0 |  |  |  |  |  |
Percentage of silver produced | 0.20 |  |  |  |  |  |
Percentage of cash price of spot silver price | 0.20 |  |  |  |  |  |
Number of ounces of silver | oz | 500 |  |  |  |  |  |

X
- Definition Consideration To Be Received, Value + References No definition available. + Details
Name: | agi_ConsiderationToBeReceivedValue
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Disclosure of detailed information about investment property [Line Items] + References No definition available. + Details
Name: | agi_DisclosureOfDetailedInformationAboutInvestmentPropertyLineItems
Namespace Prefix: | agi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Impairment loss (reversal of impairment loss) recognised in profit or loss, after tax + References No definition available. + Details
Name: | agi_ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLossAfterTax
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Milestone Payment + References No definition available. + Details
Name: | agi_MilestonePayment
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Milestone Payments And Cash From Percentage of Silver Produced + References No definition available. + Details
Name: | agi_MilestonePaymentsAndCashFromPercentageOfSilverProduced
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of Days To Receive Milestone Payment, Period + References No definition available. + Details
Name: | agi_NumberOfDaysToReceiveMilestonePaymentPeriod
Namespace Prefix: | agi_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Ounces of Silver + References No definition available. + Details
Name: | agi_NumberOfOuncesOfSilver
Namespace Prefix: | agi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of Cash Price of Spot Silver Price + References No definition available. + Details
Name: | agi_PercentageOfCashPriceOfSpotSilverPrice
Namespace Prefix: | agi_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of Silver Produced + References No definition available. + Details
Name: | agi_PercentageOfSilverProduced
Namespace Prefix: | agi_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Shares, Value + References No definition available. + Details
Name: | agi_SharesValue
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Unrealized Gain (Loss) on Derivatives1 + References No definition available. + Details
Name: | agi_UnrealizedGainLossonDerivatives1
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. [Refer: Cash; Cash equivalents] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 7 -IssueDate 2022-03-24 -Paragraph 45 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2022-en-r&anchor=para_45&doctype=Standard -URIDate 2022-03-24 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2022-03-24 -Paragraph B13 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2022-en-r&anchor=para_B13_a&doctype=Appendix&subtype=B -URIDate 2022-03-24 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2022-03-24 -Paragraph 54 -Subparagraph i -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2022-en-r&anchor=para_54_i&doctype=Standard -URIDate 2022-03-24 + Details
Name: | ifrs-full_CashAndCashEquivalents
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of consideration paid or received in respect of both obtaining and losing control of subsidiaries or other businesses. [Refer: Subsidiaries [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 7 -IssueDate 2022-03-24 -Paragraph 40 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2022-en-r&anchor=para_40_a&doctype=Standard -URIDate 2022-03-24 + Details
Name: | ifrs-full_ConsiderationPaidReceived
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of impairment loss or reversal of impairment loss recognised in profit or loss. [Refer: Impairment loss recognised in profit or loss; Reversal of impairment loss recognised in profit or loss] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2022-03-24 -Paragraph 99 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2022-en-r&anchor=para_99&doctype=Standard -URIDate 2022-03-24 + Details
Name: | ifrs-full_ImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow from the disposal of non-current assets or disposal groups classified as held for sale and discontinued operations. [Refer: Discontinued operations [member]; Disposal groups classified as held for sale [member]; Non-current assets or disposal groups classified as held for sale] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 7 -IssueDate 2022-03-24 -Paragraph 16 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2022-en-r&anchor=para_16&doctype=Standard -URIDate 2022-03-24 + Details
Name: | ifrs-full_ProceedsFromDisposalOfNoncurrentAssetsOrDisposalGroupsClassifiedAsHeldForSaleAndDiscontinuedOperations
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_CounterpartyNameAxis=agi_MetallaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ImpairmentOfFinancialAssetsAxis=agi_TransactionCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | agi_MilestoneAxis=agi_MilestoneOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | agi_MilestoneAxis=agi_MilestoneTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | agi_MilestoneAxis=agi_MilestoneThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ContinuingAndDiscontinuedOperationsAxis=ifrs-full_DiscontinuedOperationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | agi_ProjectNameAxis=agi_EsperanzaProjectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |