Net income per common share - Reconciliation of numerator used for calculation of diluted net income per common share (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Earnings per share [abstract]
Numerator for basic net income per common share	$ 79,876	$ 163,986
Adjustment for the effect of TSARs:
Cash-settled (recovery) expense included in net income	(7,902)	1,995
Equity-settled expense	(4,565)	(4,385)
Numerator for diluted net income per common share	$ 67,409	$ 161,596

No definition available.

Name:	ifrs-full_EarningsPerShareAbstract
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The profit (loss) attributable to ordinary equity holders of the parent entity. [Refer: Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 33
-IssueDate 2025-01-01
-Paragraph 70
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=33&code=ifrs-tx-2025-en-r&anchor=para_70_a&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_ProfitLossAttributableToOrdinaryEquityHoldersOfParentEntity
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The profit (loss) attributable to ordinary equity holders of the parent entity, adjusted for the effects of all dilutive potential ordinary shares. [Refer: Profit (loss)]

+ References

+ Details

Name:	ifrs-full_ProfitLossAttributableToOrdinaryEquityHoldersOfParentEntityIncludingDilutiveEffects
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Dilutive Securities, Effect on Basic Earnings Per Share, Share-Based Compensation Arrangements

+ References

No definition available.

+ Details

Name:	mx_DilutiveSecuritiesEffectonBasicEarningsPerShareShareBasedCompensationArrangementsAbstract
Namespace Prefix:	mx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Dilutive Securities, Effect on Basic Earnings Per Share, Tandem Stock Appreciation Rights, Cash-Settled Recovery

+ References

No definition available.

+ Details

Name:	mx_DilutiveSecuritiesEffectonBasicEarningsPerShareTandemStockAppreciationRightsCashSettledRecovery
Namespace Prefix:	mx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Dilutive Securities, Effect on Basic Earnings Per Share,Tandem Stock Appreciation Rights, Equity-Settled Expense

+ References

No definition available.

+ Details

Name:	mx_DilutiveSecuritiesEffectonBasicEarningsPerShareTandemStockAppreciationRightsEquitySettledExpense
Namespace Prefix:	mx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration