Note 18 - Related Party Transactions - Incurred Expenses With Cascabel and IMDEX (Details) - Cascabel and IMDEX [member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Statement Line Items [Line Items]
Exploration and marketing services	$ 372	$ 436
Travel and expenses	30	29
Administration for Mexican subsidiaries	54	54
Field exploration services	165	167
Share-based payments (Note 13)	456	477
Expenses incurred for related parties	$ 1,077	$ 1,163

The amount incurred for related parties.

No definition available.

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The expenses incurred for related parties in regards to the administration for foreign subsidiaries.

No definition available.

Name:	mag_ExpensesIncurredForRelatedPartiesAdministrationForForeignSubsidiaries
Namespace Prefix:	mag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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The expenses incurred for related parties regarding exploration and marketing services.

No definition available.

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Namespace Prefix:	mag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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The expenses incurred for related parties during field exploration services.

No definition available.

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Namespace Prefix:	mag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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The expenses incurred for related parties for share based payments.

No definition available.

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Namespace Prefix:	mag_
Data Type:	xbrli:monetaryItemType
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The expenses incurred for related parties in regards to the travel and expenses.

No definition available.

Name:	mag_ExpensesIncurredForRelatedPartiesTravelAndExpenses
Namespace Prefix:	mag_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

No definition available.

Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=mag_CascabelAndIMDEXMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: