XML 63 R31.htm IDEA: XBRL DOCUMENT v3.21.1

Decommissioning Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Asset Retirement Obligation Disclosure1 [Abstract]

Schedule of Change in Asset Retirement Obligation

A continuity of the decommissioning liability is as follows:

			Total
Balance – current and non-current portion December 31, 2018			$44.9
Reclamation expenditures			(2.0)
Accretion expense			2.8
Revisions to expected discounted cash flows			13.3
Balance – current and non-current portion December 31, 2019			$59.0
Reclamation expenditures			(3.5)
Accretion expense			2.6
Revisions to expected discounted cash flows			17.1
Balance – current and non-current portion December 31, 2020			$75.2

X

- Definition

Asset Retirement Obligation Disclosure1 [Abstract]

+ References

No definition available.

+ Details

Name:	agi_AssetRetirementObligationDisclosure1Abstract
Namespace Prefix:	agi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The disclosure of other provisions. [Refer: Other provisions]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 37
-IssueDate 2020-01-01
-Paragraph 84
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=37&code=ifrs-tx-2020-en-r&anchor=para_84&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_DisclosureOfOtherProvisionsExplanatory
Namespace Prefix:	ifrs-full_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration