XML 48 R211.htm IDEA: XBRL DOCUMENT
v3.20.1

Related Party Transactions - Additional Information (Detail) shares in Thousands, $ in Thousands, $ in Thousands | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jul. 31, 2019 TWD ($) shares | Jul. 31, 2019 USD ($) shares | Feb. 28, 2018 TWD ($) shares | Dec. 31, 2019 TWD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 TWD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 TWD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2019 USD ($)
ASE Cultural and Educational Foundation [member] | Environmental charity [member] |  |  |  |  |  |  |  |  |  |
Disclosure of transactions between related parties [line items] |  |  |  |  |  |  |  |  |  |
Amount contributed related party transactions |  |  |  | $ 100,000 | $ 3,343 | $ 100,000 | $ 3,343 | $ 100,000 | $ 3,343 |
Associates [member] |  |  |  |  |  |  |  |  |  |
Disclosure of transactions between related parties [line items] |  |  |  |  |  |  |  |  |  |
Real estate properties acquired |  |  |  | $ 2,326,000 |  |  |  |  |  | $ 77,767
USI Enterprise Limited [member] |  |  |  |  |  |  |  |  |  |
Disclosure of transactions between related parties [line items] |  |  |  |  |  |  |  |  |  |
Repurchase of outstanding ordinary shares | shares | 2,805 | 2,805 | 1,283 |  |  |  |  |  |  |
Value of ordinary shares purchased | $ 1,247,187 | $ 41,698 | $ 653,244 |  |  |  |  |  |  |

X
- Definition Amount contributed related party transactions. + References No definition available. + Details
Name: | asx_AmountContributedRelatedPartyTransactions
Namespace Prefix: | asx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Real estate property recognised as of acquisition date. + References No definition available. + Details
Name: | asx_RealEstatePropertyRecognisedAsOfAcquisitionDate
Namespace Prefix: | asx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Repurchase of outstanding ordinary shares. + References No definition available. + Details
Name: | asx_RepurchaseOfOutstandingOrdinaryShares
Namespace Prefix: | asx_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of ordinary shares repurchased. + References No definition available. + Details
Name: | asx_ValueOfOrdinarySharesRepurchased
Namespace Prefix: | asx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_DisclosureOfTransactionsBetweenRelatedPartiesLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ifrs-full_CategoriesOfRelatedPartiesAxis=asx_ASECulturalAndEducationalFoundationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfContractsAxis=asx_EnvironmentalCharityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_CategoriesOfRelatedPartiesAxis=ifrs-full_AssociatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ConsolidatedStructuredEntitiesAxis=asx_USIEnterpriseLimitedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |