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Financial Instruments - Net Effects Of Derivative Financial Instruments That Did Not Met Hedging Criteria (Detail) - Derivative Contract Not Met Hedging Criteria [member] - Market value gain (loss) on financial instruments [member] - MXN ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Foreign exchange forward contracts [member]
Disclosure of detailed information about hedges [line items]
Net gains (losses) on change in fair value of derivatives		$ 4	$ (12)
Cross-currency swaps [member]
Disclosure of detailed information about hedges [line items]
Net gains (losses) on change in fair value of derivatives	$ (212)	$ (293)	$ (116)

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- 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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- Definition

The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 85
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_85&doctype=Standard
-URIDate 2020-01-01

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