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Trade and Other Receivables - Summary of Aging Analysis of Trade Receivables (Detail) - KRW (₩) ₩ in Millions | Dec. 31, 2017 | Dec. 31, 2016
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Disclosure of financial assets [line items] |  |
Trade receivables | ₩ 3,192,538 | ₩ 2,935,552
Gross carrying amount [member] | Neither past due nor impaired [member] |  |
Disclosure of financial assets [line items] |  |
Trade receivables | 2,661,406 | 2,377,637
Gross carrying amount [member] | Past due and impaired [member] |  |
Disclosure of financial assets [line items] |  |
Trade receivables | 970,559 | 1,028,786
Gross carrying amount [member] | Past due and impaired [member] | Up to 6 months [member] |  |
Disclosure of financial assets [line items] |  |
Trade receivables | 701,032 | 685,288
Gross carrying amount [member] | Past due and impaired [member] | 6 months to 12 months [member] |  |
Disclosure of financial assets [line items] |  |
Trade receivables | 70,190 | 87,547
Gross carrying amount [member] | Past due and impaired [member] | Over 12 months [member] |  |
Disclosure of financial assets [line items] |  |
Trade receivables | 199,337 | 255,951
Allowance for doubtful accounts [member] |  |
Disclosure of financial assets [line items] |  |
Trade receivables | ₩ (439,427) | ₩ (470,871)

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