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Other Financial Assets and Liabilities - Summary of Financial Assets at Fair Value Through Other Comprehensive Income (Detail) - KRW (₩) ₩ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Financial assets at fair value through other comprehensive income [line items] |  |
Equity Instruments | ₩ 258,516 | ₩ 557,342
Less: non-current | (258,516) | (556,147)
Current |  |
Equity Instruments Listed [member] |  |
Financial assets at fair value through other comprehensive income [line items] |  |
Equity Instruments | 6,216 | 6,738
Equity Instruments Unlisted [member] |  |
Financial assets at fair value through other comprehensive income [line items] |  |
Equity Instruments | 245,730 | 543,518
Debt securities [member] |  |
Financial assets at fair value through other comprehensive income [line items] |  |
Equity Instruments | ₩ 6,570 | ₩ 7,086

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