XML 76 R45.htm IDEA: XBRL DOCUMENT
v3.19.1

Amounts Receivable (Details) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Receivables [Line Items] |  |
Other receivables | $ 6.7 | $ 4.0
Trade and other current receivables | 40.5 | 41.0
Canada |  |
Receivables [Line Items] |  |
Sales tax receivables | 10.6 | 6.4
Mexico |  |
Receivables [Line Items] |  |
Sales tax receivables | 17.5 | 26.5
Other |  |
Receivables [Line Items] |  |
Sales tax receivables | 3.4 | 0.9
Concentrate receivable | $ 2.3 | $ 3.2

X
- Definition Concentrate Receivable + References No definition available. + Details
Name: | agi_ConcentrateReceivable
Namespace Prefix: | agi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition [Line Items] for Receivables [Table] + References No definition available. + Details
Name: | agi_ReceivablesLineItems
Namespace Prefix: | agi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of current other receivables. [Refer: Other receivables] + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 78 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_78_b&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_OtherCurrentReceivables
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of current trade receivables and current other receivables. [Refer: Current trade receivables; Other current receivables] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 54 -Subparagraph h -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_54_h&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 78 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_78_b&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_TradeAndOtherCurrentReceivables
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of receivables related to a value added tax. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 78 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_78_b&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_ValueAddedTaxReceivables
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=ifrs-full_CountryOfDomicileMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=agi_MXMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=ifrs-full_ForeignCountriesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |