XML 147 R128.htm IDEA: XBRL DOCUMENT
v3.19.1

Long-term Prepayments for Lease - Additional Information (Detail) | 12 Months Ended
--- | ---
Dec. 31, 2018
Disclosure of finance lease and operating lease by lessee [line items] |
Long-term lease expire date | Through 2048 to 2089
Bottom of range [member] |
Disclosure of finance lease and operating lease by lessee [line items] |
Long-term lease period | 30 years
Top of range [member] |
Disclosure of finance lease and operating lease by lessee [line items] |
Long-term lease period | 70 years

X
- Definition Long term lease expire date. + References No definition available. + Details
Name: | asx_LongTermLeaseExpireDate
Namespace Prefix: | asx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Long term lease period. + References No definition available. + Details
Name: | asx_LongTermLeasePeriod
Namespace Prefix: | asx_
Data Type: | xbrli:durationItemType
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_DisclosureOfFinanceLeaseAndOperatingLeaseByLesseeLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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: |