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Income Tax Expense - Details of Deferred Tax Assets (Liabilities) (Detail) $ in Thousands, $ in Thousands | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2023 TWD ($) | Dec. 31, 2022 TWD ($) | Dec. 31, 2021 TWD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2020 TWD ($)
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Deferred tax assets | $ 163,282 | $ 159,286 | $ 180,598 | $ 5,333 | $ 185,691
Deferred tax liabilities | (127,193) | (201,741) | (278,177) | $ (4,154) | $ (310,427)
Deferred tax assets unrealized loss on inventories [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | 21,126 | 24,317 | 15,963 |  |
Recognized in profit or loss | 16,127 | (3,191) | 8,354 |  |
Ending balance | 37,253 | 21,126 | 24,317 |  |
Property, plant and equipment, deferred tax assets [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | 38,894 | 36,636 | 36,401 |  |
Ending balance | 40,741 | 38,894 | 36,636 |  |
Provisions [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | 12,859 | 2,849 | 2,678 |  |
Recognized in profit or loss | 1,518 | 10,010 | 171 |  |
Ending balance | 14,377 | 12,859 | 2,849 |  |
Deferred tax assets deferred revenue [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | 8,132 | 14,638 | 21,144 |  |
Recognized in profit or loss | (6,506) | (6,506) | (6,506) |  |
Ending balance | 1,626 | 8,132 | 14,638 |  |
Net defined benefit liability [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | 48,433 | 97,248 | 98,921 |  |
Recognized in profit or loss | (4,236) | (4,368) | (4,672) |  |
Recognized in other comprehensive income | (2,140) | (44,447) | 2,999 |  |
Ending balance | 42,057 | 48,433 | 97,248 |  |
Unrealized exchange losses deferred tax assets [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | 24,217 | 2,161 | 9,915 |  |
Recognized in profit or loss | (6,032) | 22,056 | (7,754) |  |
Ending balance | 18,185 | 24,217 | 2,161 |  |
Others [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | 5,625 | 2,749 | 669 |  |
Recognized in profit or loss | 3,418 | 2,876 | 2,080 |  |
Ending balance | 9,043 | 5,625 | 2,749 |  |
Deferred tax asset [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | 159,286 | 180,598 | 185,691 |  |
Recognized in profit or loss | 6,136 | 23,135 | (8,092) |  |
Recognized in other comprehensive income | (2,140) | (44,447) | 2,999 |  |
Ending balance | 163,282 | 159,286 | 180,598 |  |
Property, plant and equipment, deferred tax liabilities [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | (116,974) | (192,687) | (255,484) |  |
Recognized in profit or loss | 42,142 | 75,713 | 62,797 |  |
Ending balance | (74,832) | (116,974) | (192,687) |  |
Property, plant and equipment [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Recognized in profit or loss | 1,847 | 2,258 | 235 |  |
Financial assets at fair value through other comprehensive income [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | (72,843) | (85,402) | (54,943) |  |
Recognized in other comprehensive income | 51,638 | 12,559 | (30,459) |  |
Ending balance | (21,205) | (72,843) | (85,402) |  |
Gain on investment in associates [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | (11,923) |  |  |  |
Recognized in profit or loss | (19,228) | (11,923) |  |  |
Ending balance | (31,151) | (11,923) |  |  |
Others [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | (1) | (88) |  |  |
Recognized in profit or loss | (4) | 87 | (88) |  |
Ending balance | (5) | (1) | (88) |  |
Deferred tax liabilities [member] |  |  |  |  |
Disclosure of the detail of deferred tax assets and liabilities [line items] |  |  |  |  |
Beginning balance | (201,741) | (278,177) | (310,427) |  |
Recognized in profit or loss | 22,910 | 63,877 | 62,709 |  |
Recognized in other comprehensive income | 51,638 | 12,559 | (30,459) |  |
Ending balance | $ (127,193) | $ (201,741) | $ (278,177) |  |

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