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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, 2021 $ / shares	Dec. 31, 2021 TWD ($) $ / shares shares	Dec. 31, 2020 TWD ($) $ / shares shares	Dec. 31, 2019 TWD ($) $ / shares shares
Basic earnings per share, amount after tax
Equity holders of the Company - Amount after tax | $		$ 4,937,267	$ 2,378,978	$ 2,508,574
Diluted earnings per share, amount after tax
Equity holders of the Company - Amount after tax | $		$ 4,937,267	$ 2,378,978	$ 2,508,574
Weighted average number of ordinary shares outstanding		727,240	727,240	727,111
Diluted earnings per share, weighted-average number of ordinary shares outstanding
Employees' compensation		15,618	9,668	9,879
Restricted shares				126
Weighted average number of ordinary shares outstanding		742,858	736,908	737,116
Ordinary shares [member]
Basic earnings per share
Equity holders of the Company - Earnings per share | (per share)	$ 0.24	$ 6.79	$ 3.27	$ 3.45
Diluted earnings per share
Equity holders of the Company - Earnings per share | (per share)	$ 0.24	$ 6.65	$ 3.23	$ 3.40

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- Definition

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 number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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Adjusted weighted average number of employees' compensations outstanding.

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Diluted earnings per share attributable to ordinary equity holders of parent entity.

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