Geographic and Other Information - Additional Information (Detail) - KRW (₩) ₩ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of geographical areas [Line Items]
Sales revenue	₩ 23,475,567	₩ 24,336,571	₩ 27,790,216
Company A [member]
Disclosure of geographical areas [Line Items]
Sales revenue	8,494,720	7,262,255	9,027,165
Company B [member]
Disclosure of geographical areas [Line Items]
Sales revenue	₩ 4,501,790	₩ 5,171,354	₩ 6,511,961
Top 10 Companies [member]
Disclosure of geographical areas [Line Items]
Percentage of sales revenue	80.00%	77.00%	81.00%

Expiry date 2020-01-01: The income arising in the course of an entity's ordinary activities. Income is increases in economic benefits during the accounting period in the form of inflows or enhancements of assets or decreases of liabilities that result in an increase in equity, other than those relating to contributions from equity participants. Effective 2020-01-01: The income arising in the course of an entity's ordinary activities. Income is increases in assets, or decreases in liabilities, that result in increases in equity, other than those relating to contributions from holders of equity claims.

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+ Details