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Cash Generated from Operations - Summary of Cash Flows from Operating Activities (Parenthetical) (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Cash flows from (used in) operating activities [abstract] |  |  |
Interest income recognized as operating revenue | ₩ 21,018 | ₩ 21,021 | ₩ 15,561
Interest expense recognized as operating expense | ₩ 548 | ₩ 21 | ₩ 0

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