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Deferred Income Tax and Income Tax Expense - Summary of expected period of expiry for unused tax losses not recognized in deferred tax assets (Detail) - KRW (₩) ₩ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | ₩ 127,793 | ₩ 142,075
2021 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 2,140 | 18,582
2022 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 80,649 | 2,140
2023 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 5,848 | 80,649
2024 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 4,867 | 5,848
2025 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 2,847 | 4,867
2026 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 9,709 | 9,390
2027 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 8,389 | 7,888
2028 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 8,426 | 10,064
2029 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | 2,579 | 2,030
2030 |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |
Unused tax losses for which no deferred tax asset recognised | ₩ 2,339 | ₩ 617

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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
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- Definition The amount of unused tax losses for which no deferred tax asset is recognised in the statement of financial position. [Refer: Unused tax losses [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2020-01-01 -Paragraph 81 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2020-en-r&anchor=para_81_e&doctype=Standard -URIDate 2020-01-01 + Details
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