XML 143 R127.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Retirement Benefit Plans - Summary of Defined Benefit Plans Amounts Included in Consolidated Balance Sheets (Detail) $ in Thousands, $ in Thousands | Dec. 31, 2017 TWD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 TWD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 TWD ($) | Dec. 31, 2014 TWD ($)
--- | --- | --- | --- | --- | --- | ---
Disclosure of net defined benefit liability (asset) [abstract] |  |  |  |  |  |
Present value of the defined benefit obligation | $ 7,910,638 | $ 266,891 | $ 8,389,884 |  |  |
Fair value of plan assets | (4,341,373) | (146,470) | (4,417,367) |  |  |
Present value of unfunded defined benefit obligation | 3,569,265 | 120,421 | 3,972,517 | $ 134,026 | $ 3,999,947 | $ 4,171,806
Recorded under other payables | (24,638) | (831) | (22,273) |  |  |
Recorded under other current assets | 182,421 | 6,154 | 15,542 |  |  |
Net defined benefit liability | $ 3,727,048 | $ 125,744 | $ 3,965,786 |  |  |

X
- Definition Defined benefit plan recorded under others payables. + References No definition available. + Details
Name: | asx_DefinedBenefitPlanRecordedUnderOthersPayables
Namespace Prefix: | asx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Net defined benefit liability. + References No definition available. + Details
Name: | asx_NetDefinedBenefitLiability
Namespace Prefix: | asx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Recorded under other current assets. + References No definition available. + Details
Name: | asx_RecordedUnderOtherCurrentAssets
Namespace Prefix: | asx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The present value, without deducting any plan assets, of expected future payments required to settle the obligation resulting from employee service in the current and prior periods. [Refer: Plan assets, at fair value] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_57_a&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_DefinedBenefitObligationAtPresentValue
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | ifrs-full_DisclosureOfNetDefinedBenefitLiabilityAssetAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 140 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_140_a&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_LiabilityAssetOfDefinedBenefitPlans
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fair value of defined benefit plan assets. Plan assets comprise assets held by a long-term employee benefit fund and qualifying insurance policies. [Refer: At fair value [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_57_a&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_PlanAssetsAtFairValue
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant