Accounts Payable, Accrued Liabilities and Asset Retirement Obligations - Summary of Movements in Asset Retirement Obligations (Detail) - MXN ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Disclosure of asset retirement obligations [abstract]
Beginning balance	$ 15,816,744	$ 15,971,601
Business combination		293,548
Effect of translation	374,418	(1,339,033)
Increase of the year	2,412,908	1,600,197
Applications payments	(593,644)	(128,842)
Applications reversals	(122,435)	(580,727)
Ending balance	$ 17,887,991	$ 15,816,744

Applications, payments of asset retirement obligations, non-current.

No definition available.

Name:	amx_ApplicationsPaymentsOfAssetRetirementObligationsNoncurrent
Namespace Prefix:	amx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Applications, reversals of asset retirement obligations, non-current.

No definition available.

Name:	amx_ApplicationsReversalsOfAssetRetirementObligationsNoncurrent
Namespace Prefix:	amx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Disclosure of asset retirement obligations.

No definition available.

Name:	amx_DisclosureOfAssetRetirementObligationsAbstract
Namespace Prefix:	amx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Effect of exchange rate changes on asset retirement obligations, non-current.

No definition available.

Name:	amx_EffectOfExchangeRateChangesOnAssetRetirementObligationsNoncurrent
Namespace Prefix:	amx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Increase (decrease) in asset retirement obligations during period, non-current.

No definition available.

Name:	amx_IncreaseDecreaseInAssetRetirementObligationsDuringPeriodNoncurrent
Namespace Prefix:	amx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Movements in asset retirement obligation related to business combinations current.

No definition available.

Name:	amx_MovementsInAssetRetirementObligationRelatedToBusinessCombinationsCurrent
Namespace Prefix:	amx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Noncurrent asset retirement obligations.

No definition available.

Name:	amx_NoncurrentAssetRetirementObligations
Namespace Prefix:	amx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant