XML 87 R71.htm IDEA: XBRL DOCUMENT
v3.20.4

Segmented Information (Segment revenues and results) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Disclosure of operating segments [line items] |  |
Operating revenues | $ 748.1 | $ 683.1
Cost of sales |  |
Cost of sales | 312.6 | 339.0
Royalties | 10.2 | 17.4
COVID costs | 6.5 | 0.0
Amortization | 152.7 | 165.0
Cost of sales | 482.0 | 521.4
Expenses |  |
Exploration | 7.2 | 6.7
Corporate and administrative | 21.0 | 19.8
Share-based compensation | 10.3 | 9.2
EARNINGS FROM OPERATIONS | 227.6 | 126.0
Finance expense | (4.3) | (2.5)
Foreign exchange loss | (1.4) | 0.3
Other gain | (3.7) | 5.1
EARNINGS BEFORE INCOME TAXES | 218.2 | 128.9
Operating segments [member] | Young-Davidson [Member] |  |
Disclosure of operating segments [line items] |  |
Operating revenues | 239.4 | 262.1
Cost of sales |  |
Cost of sales | 133.9 | 146.6
Royalties | 3.7 | 4.4
COVID costs | 0.0 |
Amortization | 63.7 | 80.1
Cost of sales | 201.3 | 231.1
Expenses |  |
Exploration | 0.0 | 0.0
Corporate and administrative | 0.0 | 0.0
Share-based compensation | 0.0 | 0.0
EARNINGS FROM OPERATIONS | 38.1 | 31.0
Operating segments [member] | Mulatos [Member] |  |
Disclosure of operating segments [line items] |  |
Operating revenues | 261.7 | 194.4
Cost of sales |  |
Cost of sales | 120.9 | 107.8
Royalties | 1.3 | 3.1
COVID costs | 2.0 |
Amortization | 44.6 | 28.0
Cost of sales | 168.8 | 138.9
Expenses |  |
Exploration | 4.2 | 3.6
Corporate and administrative | 0.0 | 0.0
Share-based compensation | 0.0 | 0.0
EARNINGS FROM OPERATIONS | 88.7 | 51.9
Operating segments [member] | Island Gold [Member] |  |
Disclosure of operating segments [line items] |  |
Operating revenues | 247.0 | 207.3
Cost of sales |  |
Cost of sales | 57.8 | 64.2
Royalties | 5.2 | 9.9
COVID costs | 4.5 |
Amortization | 44.4 | 55.3
Cost of sales | 111.9 | 129.4
Expenses |  |
Exploration | 1.0 | 1.1
Corporate and administrative | 0.0 |
Share-based compensation | 0.0 |
EARNINGS FROM OPERATIONS | 134.1 | 76.8
Operating segments [member] | El Chanate [Member] |  |
Disclosure of operating segments [line items] |  |
Operating revenues |  | 19.3
Cost of sales |  |
Cost of sales |  | 20.4
Royalties |  | 0.0
Amortization |  | 1.6
Cost of sales |  | 22.0
Expenses |  |
Exploration |  | 0.0
Corporate and administrative |  | 0.0
Share-based compensation |  | 0.0
EARNINGS FROM OPERATIONS |  | (2.7)
Corporate and other [Member] |  |
Disclosure of operating segments [line items] |  |
Operating revenues | 0.0 | 0.0
Cost of sales |  |
Cost of sales | 0.0 | 0.0
Royalties | 0.0 | 0.0
COVID costs | 0.0 |
Amortization | 0.0 | 0.0
Cost of sales | 0.0 | 0.0
Expenses |  |
Exploration | 2.0 | 2.0
Corporate and administrative | 21.0 | 19.8
Share-based compensation | 10.3 | 9.2
EARNINGS FROM OPERATIONS | $ (33.3) | $ (31.0)

X
- Definition Amortization, Cost of Sales, Extractive Activities + References No definition available. + Details
Name: | agi_AmortizationCostofSalesExtractiveActivities
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

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

X
- Definition Mining and Processing + References No definition available. + Details
Name: | agi_MiningandProcessing
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition other nonoperating income (expense) + References No definition available. + Details
Name: | agi_OtherNonoperatingIncomeExpense1
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of expenses that the entity classifies as being administrative. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 26 -IssueDate 2020-01-01 -Paragraph 35 -Subparagraph b -Clause vi -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=26&code=ifrs-tx-2020-en-r&anchor=para_35_b_vi&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 103 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_103&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 99 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_99&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_AdministrativeExpense
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of costs relating to expenses directly or indirectly attributed to the goods or services sold, which may include, but are not limited to, costs previously included in the measurement of inventory that has now been sold, unallocated production overheads and abnormal amounts of production costs of inventories. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 99 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_99&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 103 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_103&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_CostOfSales
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition The amount of expense arising from the search for mineral resources, including minerals, oil, natural gas and similar non-regenerative resources after the entity has obtained legal rights to explore in a specific area, as well as the determination of the technical feasibility and commercial viability of extracting the mineral resource. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 6 -IssueDate 2020-01-01 -Paragraph 24 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=6&code=ifrs-tx-2020-en-r&anchor=para_24_b&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_ExpenseArisingFromExplorationForAndEvaluationOfMineralResources
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_ExpenseByNatureAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of expense from share-based payment transactions with employees. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_112_c&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_ExpenseFromSharebasedPaymentTransactionsWithEmployees
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of costs associated with financing activities of the entity. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 82 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_82_b&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_FinanceCosts
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Financial instruments, class [member]] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 7 -IssueDate 2020-01-01 -Section A Statement of cash flows for an entity other than a financial institution -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&doctype=Illustrative%20Examples&dita_xref=IAS07_IE_A_TI -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 21 -IssueDate 2020-01-01 -Paragraph 52 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=21&code=ifrs-tx-2020-en-r&anchor=para_52_a&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The profit (loss) before tax expense or income. [Refer: Profit (loss)] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 8 -IssueDate 2020-01-01 -Paragraph 28 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2020-en-r&anchor=para_28_b&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 8 -IssueDate 2020-01-01 -Paragraph 23 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2020-en-r&anchor=para_23&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 103 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_103&doctype=Standard -URIDate 2020-01-01 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 102 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_102&doctype=Standard -URIDate 2020-01-01 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 5 -IssueDate 2020-01-01 -Paragraph 33 -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=5&code=ifrs-tx-2020-en-r&anchor=para_33_b_i&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_ProfitLossBeforeTax
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The profit (loss) from operating activities of the entity. [Refer: Profit (loss)] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 32 -IssueDate 2020-01-01 -Paragraph IE33 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=32&code=ifrs-tx-2020-en-r&anchor=para_IE33&doctype=Illustrative%20Examples -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_85&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_ProfitLossFromOperatingActivities
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The income arising in the course of an entity's ordinary activities. Income is increases in assets, or decreases in liabilities, that result in increases in equity, other than those relating to contributions from holders of equity claims. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2020-01-01 -Paragraph 28 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2020-en-r&anchor=para_28_a&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2020-01-01 -Paragraph 23 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2020-en-r&anchor=para_23_a&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2020-01-01 -Paragraph 32 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2020-en-r&anchor=para_32&doctype=Standard -URIDate 2020-01-01 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2020-01-01 -Paragraph 33 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2020-en-r&anchor=para_33_a&doctype=Standard -URIDate 2020-01-01 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2020-01-01 -Paragraph 34 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2020-en-r&anchor=para_34&doctype=Standard -URIDate 2020-01-01 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 82 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_82_a&doctype=Standard -URIDate 2020-01-01 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 103 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_103&doctype=Standard -URIDate 2020-01-01 Reference 8: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 102 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_102&doctype=Standard -URIDate 2020-01-01 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 5 -IssueDate 2020-01-01 -Paragraph 33 -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=5&code=ifrs-tx-2020-en-r&anchor=para_33_b_i&doctype=Standard -URIDate 2020-01-01 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph B12 -Subparagraph b -Clause v -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_B12_b_v&doctype=Appendix&subtype=B -URIDate 2020-01-01 Reference 11: http://www.xbrl.org/2003/role/exampleRef -Name IFRS -Number 12 -IssueDate 2020-01-01 -Paragraph B10 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_B10_b&doctype=Appendix&subtype=B -URIDate 2020-01-01 + Details
Name: | ifrs-full_Revenue
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of expense arising from royalties. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_85&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_RoyaltyExpense
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | ifrs-full_SegmentConsolidationItemsAxis=ifrs-full_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SegmentsAxis=agi_YoungDavidsonSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SegmentsAxis=agi_MulatosSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SegmentsAxis=agi_IslandGoldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SegmentsAxis=agi_ElChanateSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SegmentConsolidationItemsAxis=agi_CorporateNonSegment1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |