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Retirement Benefit Plans - Summary of Defined Benefit Plans Amounts Included in Consolidated Balance Sheets (Detail) $ in Thousands, $ in Thousands | Dec. 31, 2021 TWD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 TWD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 TWD ($) | Dec. 31, 2018 TWD ($)
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Disclosure of net defined benefit liability (asset) [abstract] |  |  |  |  |  |
Present value of the defined benefit obligation | $ 11,424,860 | $ 411,855 | $ 12,159,145 |  |  |
Fair value of the plan assets | (5,863,264) | (211,365) | (5,962,305) |  |  |
Present value of unfunded defined benefit obligation | 5,561,596 | 200,490 | 6,196,840 | $ 223,390 | $ 4,926,396 | $ 4,805,016
Recorded under other payables | (67,524) | (2,434) | (102,367) |  |  |
Recorded under other non-current assets |  |  | 26,306 |  |  |
Net defined benefit liability | $ 5,494,072 | $ 198,056 | $ 6,120,779 |  |  |

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- Definition Defined benefit plan recorded under others payables. + References No definition available. + Details
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- Definition Net defined benefit liability. + References No definition available. + Details
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- Definition Recorded under other non current assets. + References No definition available. + Details
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- 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 2021-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_57_a&doctype=Standard -URIDate 2021-03-24 + Details
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- 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 2021-01-01 -Paragraph 140 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_140_a&doctype=Standard -URIDate 2021-03-24 + Details
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- 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 2021-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_57_a&doctype=Standard -URIDate 2021-03-24 + Details
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