XML 220 R204.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Others - Additional Information (Detail) - TWD ($) $ / shares in Units, $ in Thousands |  | 12 Months Ended
--- | --- | ---
Dec. 20, 2013 | Dec. 31, 2017
Disclosure Detailed Information About Others [Line Items] |  |
Administrative fine imposed | $ 102,014 |
Estimated cash consideration description |  | The estimated cash consideration paid per SPIL's ordinary share shall not be subject to adjustment if the aggregate amount of the cash dividends distributed by SPIL in 2017 is less than 85% of SPIL's net profit for the year ended December 31, 2016.
ASE Holding [member] |  |
Disclosure Detailed Information About Others [Line Items] |  |
Number of ordinary shares exchanged from ASE Holding |  | 0.5
Siliconware Precision Industries Co., Ltd. [member] |  |
Disclosure Detailed Information About Others [Line Items] |  |
Cash price per ordinary share |  | $ 55
Cash price per ordinary share adjusted |  | $ 51.2

X
- Definition Adjusted cash price per ordinary share. + References No definition available. + Details
Name: | asx_AdjustedCashPricePerOrdinaryShare
Namespace Prefix: | asx_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of fine imposed. + References No definition available. + Details
Name: | asx_AmountOfFineImposed
Namespace Prefix: | asx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Cash price per ordinary share. + References No definition available. + Details
Name: | asx_CashPricePerOrdinaryShare
Namespace Prefix: | asx_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Disclosure Detailed Information About Others [Line Items] + References No definition available. + Details
Name: | asx_DisclosureDetailedInformationAboutOthersLineItems
Namespace Prefix: | asx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Estimated cash consideration description. + References No definition available. + Details
Name: | asx_EstimatedCashConsiderationDescription
Namespace Prefix: | asx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

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

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