The period of time for which the borrowings are in effect.

No definition available.

Name:	fmx_BorrowingsTerm
Namespace Prefix:	fmx_
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Balance Type:	na
Period Type:	duration

- Definition

Proportion of ownership interest sold.

+ References

No definition available.

+ Details

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Namespace Prefix:	fmx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of outstanding funds that the entity is obligated to repay.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_55&doctype=Standard
-URIDate 2020-01-01

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The interest rate on borrowings. [Refer: Borrowings]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 7
-IssueDate 2020-01-01
-Paragraph 7
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2020-en-r&anchor=para_7&doctype=Standard
-URIDate 2020-01-01

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

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

- Definition

The cash outflow for repayments of bonds, notes and debentures.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 7
-IssueDate 2020-01-01
-Paragraph 17
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&anchor=para_17&doctype=Standard
-URIDate 2020-01-01

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BusinessCombinationsAxis=fmx_VonparMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=fmx_LongTermBorrowingsNotesPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Financial Instruments - Option embedded in Promissory Note (Detail) R$ in Millions, $ in Millions, $ in Millions				1 Months Ended	12 Months Ended
	Dec. 06, 2019 BRL (R$)	Dec. 06, 2019 USD ($)	Dec. 06, 2016 BRL (R$)	Sep. 30, 2020	Dec. 31, 2019 MXN ($)	Dec. 31, 2020 MXN ($)
Disclosure of detailed information about financial instruments [line items]
Borrowings \| $					$ 114,016	$ 184,196
Promissory notes paid	R$ 1,002	$ 236			$ 4,670
Spal [member] \| Vonpar [member] \| Notes payable [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings Term			3 years
Borrowings \| R$			R$ 1,166
Borrowings, interest rate			0.375%
Estrella Azul [Member]
Disclosure of detailed information about financial instruments [line items]
Proportion of ownership interest sold				100.00%