XML 157 R121.htm IDEA: XBRL DOCUMENT
v3.19.1

Employee Benefits - Summary of Assumptions Used in Determining the Net Period Cost (Detail) | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Puerto Rico [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Discount rate and long-term rate return | 4.45% | 3.61% | 4.16%
Rate of future salary increases | 2.75% | 2.75% | 3.50%
Percentage of increase in health care costs for the coming year | 3.87% | 3.57% | 4.20%
Year to which this level will be maintained | N/A | N/A | N/A
Brazil [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Discount rate and long-term rate return | 9.10% | 10.18% | 10.84%
Rate of future salary increases | 4.00% | 4.50% | 4.85%
Percentage of increase in health care costs for the coming year | 10.50% | 11.00% | 11.35%
Year to which this level will be maintained | 2029 | 2028 | 2017
Mexico [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Discount rate and long-term rate return | 11.81% | 10.70% | 10.70%
Rate of future salary increases | 3.55% | 4.50% | 4.50%
Rate of increase of pensions | 3.47% | 3.83% | 3.83%
Europe [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Discount rate and long-term rate return | 1.25% | 1.00% | 1.00%
Rate of future salary increases |  |  | 3.00%
Rate of increase of pensions | 1.60% | 1.60% | 1.60%
Europe [member] | Bottom of range [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Employee turnover rate | 0.00% | 0.00% | 0.00%
Europe [member] | Top of range [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Employee turnover rate | 1.51% | 1.72% | 1.88%
Europe [member] | Actuarial assumption rate one [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Discount rate and long-term rate return | 1.75% | 1.50% | 1.50%
Rate of future salary increases | 3.00% | 3.00% | 3.90%
Europe [member] | Actuarial assumption rate two [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Discount rate and long-term rate return | 2.00% | 2.00% | 1.75%
Rate of future salary increases | 3.50% | 3.50% | 4.40%
Europe [member] | Actuarial assumption rate three [member] |  |  |
Disclosure of sensitivity analysis for actuarial assumptions [line items] |  |  |
Rate of future salary increases | 4.40% | 4.40% |

X
- Definition Description of level of years fair value will be maintained. + References No definition available. + Details
Name: | amx_DescriptionOfLevelOfYearsFairValueWillBeMaintained
Namespace Prefix: | amx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Employee turnover rate. + References No definition available. + Details
Name: | amx_EmployeeTurnoverRate
Namespace Prefix: | amx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 144 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_144&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_ActuarialAssumptionOfDiscountRates
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The expected rate of increases in pension that is used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 144 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_144&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_ActuarialAssumptionOfExpectedRatesOfPensionIncreases
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The expected rate of salary increases used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 144 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_144&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_ActuarialAssumptionOfExpectedRatesOfSalaryIncreases
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Medical cost trend rate used as significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 144 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_144&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_ActuarialAssumptionOfMedicalCostTrendRates
Namespace Prefix: | ifrs-full_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=country_PR
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=country_BR
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=country_MX
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=srt_EuropeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ActuarialAssumptionsAxis=amx_ActuarialAssumptionRateOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ActuarialAssumptionsAxis=amx_ActuarialAssumptionRateTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ActuarialAssumptionsAxis=amx_ActuarialAssumptionRateThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |