XML 159 R107.htm IDEA: XBRL DOCUMENT
v3.20.1

Investments Accounted for Using the Equity Method - Summary of Fair Values of Investments in Associates with Available Published Price Quotation (Detail) - Level 1 of fair value hierarchy [member] $ in Thousands, $ in Thousands | Dec. 31, 2019 TWD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 TWD ($)
--- | --- | --- | ---
Hung Ching Development & Construction Co. [member] |  |  |
Disclosure of associates and joint ventures [line items] |  |  |
Fair value of investments in associates with available published price quotation | $ 1,551,033 | $ 51,857 | $ 1,537,307
Advanced Microelectronic Products Inc. [member] |  |  |
Disclosure of associates and joint ventures [line items] |  |  |
Fair value of investments in associates with available published price quotation |  |  | 369,925
ChipMOS Technologies Inc. [member] |  |  |
Disclosure of associates and joint ventures [line items] |  |  |
Fair value of investments in associates with available published price quotation | $ 5,100,181 | $ 170,518 | $ 3,886,561

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information about associate and joint ventures associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | asx_DisclosureOfAssociatesAndJointVenturesLineItems
Namespace Prefix: | asx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The fair value of investments in associates if there are quoted market prices for the investment. [Refer: Associates [member]; Investments in associates] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2019-01-01 -Paragraph 21 -Subparagraph b -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2019-en-r&anchor=para_21_b_iii&doctype=Standard -URIDate 2019-03-27 + Details
Name: | ifrs-full_FairValueOfInvestmentsInAssociatesWherePriceQuotationsPublished
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | ifrs-full_LevelsOfFairValueHierarchyAxis=ifrs-full_Level1OfFairValueHierarchyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInAssociatesAxis=asx_HungChingDevelopmentAndConstructionCoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInAssociatesAxis=asx_AdvancedMicroelectronicProductsIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInAssociatesAxis=asx_ChipMosTechnologiesIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |