Non-controlling interests - Cash flows (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Disclosure of subsidiaries [line items]
Cash flows from (used in) operating activities	$ 461,082	$ 515,431
Cash flows from (used in) financing activities	234,059	(104,053)
Cash flows from (used in) investing activities	(278,063)	(250,692)
Methanex Egypt
Disclosure of subsidiaries [line items]
Cash flows from (used in) operating activities	145,672	68,022
Cash flows from (used in) financing activities	(96,052)	(74,675)
Cash flows from (used in) investing activities	(5,309)	(8,859)
Vessels
Disclosure of subsidiaries [line items]
Cash flows from (used in) operating activities	24,951	24,267
Cash flows from (used in) financing activities	(17,344)	(21,606)
Cash flows from (used in) investing activities	(7,788)	(3,723)
Total
Disclosure of subsidiaries [line items]
Cash flows from (used in) operating activities	170,623	92,289
Cash flows from (used in) financing activities	(113,396)	(96,281)
Cash flows from (used in) investing activities	$ (13,097)	$ (12,582)

The cash flows from (used in) financing activities, which are activities that result in changes in the size and composition of the contributed equity and borrowings of the entity.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2020-01-01
-Paragraph 10
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&anchor=para_10&doctype=Standard
-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2020-01-01
-Paragraph 50
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&anchor=para_50_d&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_CashFlowsFromUsedInFinancingActivities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash flows from (used in) investing activities, which are the acquisition and disposal of long-term assets and other investments not included in cash equivalents.

+ References

+ Details

Name:	ifrs-full_CashFlowsFromUsedInInvestingActivities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash flows from (used in) operating activities, which are the principal revenue-producing activities of the entity and other activities that are not investing or financing activities. [Refer: Revenue]

+ References

+ Details

Name:	ifrs-full_CashFlowsFromUsedInOperatingActivities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

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

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=mx_EgyptianMethanexMethanolCompanyS.A.E.MethanexEgyptMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=mx_OtherSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=ifrs-full_SubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: