XML 80 R48.htm IDEA: XBRL DOCUMENT
v3.21.1

Mineral Property, Plant and Equipment (Trillium) (Details) - Dec. 17, 2020 - Trillium $ in Millions, $ in Millions | CAD ($) | USD ($)
--- | --- | ---
Disclosure of detailed information about business combination [line items] |  |
Cash transferred | $ 25.0 | $ 19.5
Cash and cash equivalents recognised as of acquisition date |  | 0.1
Current assets recognised as of acquisition date |  | $ 0.1

X
- Definition The amount recognised as of the acquisition date for cash and cash equivalents acquired in a business combination. [Refer: Cash and cash equivalents; Business combinations [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IFRS -Number 3 -IssueDate 2020-01-01 -Paragraph B64 -Subparagraph i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2020-en-r&anchor=para_B64_i&doctype=Appendix&subtype=B -URIDate 2020-01-01 + Details
Name: | ifrs-full_CashAndCashEquivalentsRecognisedAsOfAcquisitionDate
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The fair value, at acquisition date, of cash transferred as consideration in a business combination. [Refer: Business combinations [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 3 -IssueDate 2020-01-01 -Paragraph B64 -Subparagraph f -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2020-en-r&anchor=para_B64_f_i&doctype=Appendix&subtype=B -URIDate 2020-01-01 + Details
Name: | ifrs-full_CashTransferred
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount recognised as of the acquisition date for current assets acquired in a business combination. [Refer: Business combinations [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IFRS -Number 3 -IssueDate 2020-01-01 -Paragraph B64 -Subparagraph i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2020-en-r&anchor=para_B64_i&doctype=Appendix&subtype=B -URIDate 2020-01-01 + Details
Name: | ifrs-full_CurrentAssetsRecognisedAsOfAcquisitionDate
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_DisclosureOfBusinessCombinationsLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ifrs-full_BusinessCombinationsAxis=agi_TrilliumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |