Name:	asx_IncreaseDecreaseThroughAcquisitionThroughBusinessCombinationsAllowanceAccountForCreditLossesOfFinancialAssets
Namespace Prefix:	asx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Increase (decrease) through Net remeasurement of loss allowance, allowance account for credit losses of financial assets.

No definition available.

Name:	asx_IncreaseDecreaseThroughNetRemeasurementOfLossAllowanceAllowanceAccountForCreditLossesOfFinancialAssets
Namespace Prefix:	asx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Reclassification to loss allowance of other receivables.

No definition available.

Name:	asx_ReclassificationToLossAllowanceOfOtherReceivables
Namespace Prefix:	asx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of an allowance account used to record impairments to financial assets due to credit losses. [Refer: Financial assets]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2021-01-01
-Name IFRS
-Number 7
-IssueDate 2020-01-01
-Paragraph 16
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_16&doctype=Standard&book=b
-URIDate 2020-01-01

Name:	ifrs-full_AllowanceAccountForCreditLossesOfFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

No definition available.

Name:	ifrs-full_DisclosureOfFinancialAssetsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The increase (decrease) in an allowance account for credit losses of financial assets resulting from the net exchange differences arising when the financial statements are translated from the functional currency into a different presentation currency, including the translation of a foreign operation into the presentation currency of the reporting entity. [Refer: Allowance account for credit losses of financial assets]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2021-01-01
-Name IFRS
-Number 7
-IssueDate 2020-01-01
-Paragraph 16
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_16&doctype=Standard&book=b
-URIDate 2020-01-01

Name:	ifrs-full_IncreaseDecreaseThroughNetExchangeDifferencesAllowanceAccountForCreditLossesOfFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The decrease in an allowance account for credit losses of financial assets resulting from the utilisation of the allowance. [Refer: Allowance account for credit losses of financial assets]