XML 193 R174.htm IDEA: XBRL DOCUMENT
v3.19.1

Income Tax - Summary of Projects were Exempted From Income Tax (Detail) | 12 Months Ended
--- | ---
Dec. 31, 2018
Construction and expansion of 2007 by the company [member] |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |
Tax-exemption period, start date | 2016-01
Tax-exemption period, end date | 2020-12
Construction and expansion of 2007 by the company [member] | Siliconware Precision Industries Co., Ltd. [member] |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |
Tax-exemption period, start date | 2015-01
Tax-exemption period, end date | 2019-12
Construction and expansion of 2008 [member] |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |
Tax-exemption period, start date | 2014-01
Tax-exemption period, end date | 2018-12
Construction and expansion of 2008 [member] | ASE Test, Inc. [member] |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |
Tax-exemption period, start date | 2014-01
Tax-exemption period, end date | 2018-12
Construction and expansion of 2008 [member] | ASE Electronics Inc. [member] |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |
Tax-exemption period, start date | 2016-01
Tax-exemption period, end date | 2020-12
Construction and expansion of 2009 [member] | ASE Test, Inc. [member] |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |
Tax-exemption period, start date | 2018-01
Tax-exemption period, end date | 2022-12

X
- Definition Tax exemption period end date. + References No definition available. + Details
Name: | asx_TaxExemptionPeriodEndDate
Namespace Prefix: | asx_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tax exemption period start date. + References No definition available. + Details
Name: | asx_TaxExemptionPeriodStartDate
Namespace Prefix: | asx_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | ifrs-full_TypesOfInvestmentPropertyAxis=asx_ConstructionAndExpansionOfTwoThousandAndSevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInSubsidiariesAxis=asx_SiliconwarePrecisionIndustriesCoLtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfInvestmentPropertyAxis=asx_ConstructionAndExpansionOfTwoThousandAndEightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInSubsidiariesAxis=asx_ASETestIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInSubsidiariesAxis=asx_ASEElectronicsIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfInvestmentPropertyAxis=asx_ConstructionAndExpansionOfTwoThousandAndNineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |