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Earnings per Share - Summary of Basic and Diluted Earnings per Share from Operations (Detail) - KRW (₩) ₩ / shares in Units, ₩ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic earnings per share [abstract]
Profit (loss) attributable to ordinary shares	₩ 700,889	₩ 645,703	₩ 645,571
Weighted average number of ordinary shares outstanding	245,207,307	245,171,283	245,049,466
Basic earnings per share (In Korean won)	₩ 2,858	₩ 2,634	₩ 2,634
Profit attributable to ordinary shares (In millions of Korean won)	₩ 700,889	₩ 645,703	₩ 645,571
Adjustment to net income attributable to ordinary shares (In millions of Korean won)		(157)
Diluted profit attributable to ordinary shares (In millions of Korean won)	₩ 700,889	₩ 645,546	₩ 645,571
Number of dilutive potential ordinary shares outstanding	69,598	70,267	1,163
Weighted average number of ordinary shares outstanding	245,276,905	245,241,550	245,050,629
Diluted earnings per share (In Korean won)	₩ 2,858	₩ 2,632	₩ 2,634

X

- 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 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), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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