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Financial Risk Management And Fair Values Of Financial Instruments - Summary of Effect of Profit or Loss or of Other Comprehensive Income from Financial Assets Categorized (Detail) - Financial instruments at fair value through other comprehensive income [member] - TWD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items] |  |
Favorable Changes | $ 8,074 | $ 5,325
Unfavorable Changes In Fair Value | 8,074 | 5,267
Enter prise value EBITDA multiple [member] |  |
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items] |  |
Favorable Changes | 3,443 | 2,153
Unfavorable Changes In Fair Value | 3,443 | 2,153
Discount for lack of marketability [member] |  |
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items] |  |
Favorable Changes | 4,585 | 3,142
Unfavorable Changes In Fair Value | 4,585 | 3,084
Foreign unlisted stocks [member] | Price to book ratio multiple [member] |  |
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items] |  |
Favorable Changes | 46 | 30
Unfavorable Changes In Fair Value | $ 46 | $ 30

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