Earnings Per Share - Income and Share Data Used in Basic and Diluted EPS Computations (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2024 $ / shares	Dec. 31, 2024 TWD ($) $ / shares shares	Dec. 31, 2023 TWD ($) $ / shares shares	Dec. 31, 2022 TWD ($) $ / shares shares
Basic earnings per share, amount after tax
Equity holders of the Company - Amount after tax \| $		$ 1,439,536	$ 1,967,565	$ 3,439,697
Diluted earnings per share, amount after tax
Equity holders of the Company - Amount after tax \| $		$ 1,439,536	$ 1,967,565	$ 3,439,697
Weighted average number of ordinary shares outstanding		727,240	727,240	727,240
Diluted earnings per share, weighted-average number of ordinary shares outstanding
Employees' compensation		6,772	7,698	15,406
Weighted average number of ordinary shares outstanding		734,012	734,938	742,646
Ordinary shares [member]
Basic earnings per share
Equity holders of the Company - Earnings per share \| (per share)	$ 0.06	$ 1.98	$ 2.71	$ 4.73
Diluted earnings per share
Diluted earnings (loss) per share \| (per share)	$ 0.06	$ 1.96	$ 2.68	$ 4.63

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator).

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The profit (loss) attributable to ordinary equity holders of the parent entity. [Refer: Profit (loss)]

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