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Deferred Income Tax and Income Tax Expense - Summary of Tax Impacts Recognized Directly To Equity (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Deferred tax assets and liabilities [abstract] |  |  |
Loss on valuation of available-for-sale securities, Before recognition | ₩ 0 |  | ₩ (5,561)
Gain on valuation of financial assets at fair value through other comprehensive income, Before recognition | 225,635 | ₩ 59,384 |
Gain (loss) on valuation of hedge instruments (loss)liabilities, Before recognition | 31,003 | (36,756) | 40,694
Remeasurements of net defined benefit liabilities, Before recognition | (33,814) | (116,324) | (110,768)
Share of Gain (loss) of associates and joint ventures, and others, Before recognition | 4,493 | (1,036) | 13,410
Exchange differences on translation for foreign operations, Before recognition | 6,692 | 3,989 | (27,865)
Total, Before recognition | 234,009 | (90,743) | (90,090)
Loss on valuation of available-for-sale securities, Tax effect | 0 |  | 1,346
Gain on valuation of financial assets at fair value through other comprehensive income, Tax effect | (58,483) | (15,573) |
Gain (loss) on valuation of hedge instruments (loss)liabilities, Tax effect | (8,139) | 9,745 | (9,848)
Remeasurements of net defined benefit liabilities, Tax effect | 8,037 | 42,813 | 26,806
Share of Gain (loss) of associates and joint ventures, and others, Tax effect | (1,327) | 179 | (3,245)
Exchange differences on translation for foreign operations, Tax effect | (1,759) | (1,049) | 6,743
Total, Tax effect | (61,669) | 36,115 | 21,802
Loss on valuation of available-for-sale securities, After recognition | 0 |  | 4,215
Gain on valuation of financial assets at fair value through other comprehensive income, After recognition | 167,152 | 43,811 |
Gain (loss) on valuation of hedge instruments (loss)liabilities, After recognition | 22,864 | (27,011) | 30,846
Remeasurements of net defined benefit liabilities, After recognition | (25,777) | (73,511) | (83,962)
Share of Gain (loss) of associates and joint ventures, and others, After recognition | 3,166 | (857) | 10,165
Exchange differences on translation for foreign operations, After recognition | 4,933 | 2,940 | (21,122)
Total other comprehensive income (loss) | ₩ 172,338 | ₩ (54,628) | ₩ (68,288)

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- Definition The gains (losses) recognised in other comprehensive income on financial assets measured at fair value through other comprehensive income, before tax. [Refer: Financial assets measured at fair value through other comprehensive income; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2019-01-01 -Paragraph 20 -Subparagraph a -Clause viii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2019-en-r&anchor=para_20_a_viii&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 91 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_91_b&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The gains (losses) recognised in other comprehensive income on financial assets measured at fair value through other comprehensive income, net of tax. [Refer: Financial assets measured at fair value through other comprehensive income; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 91 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_91_a&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to available-for-sale financial assets. [Refer: Financial assets available-for-sale; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2021-01-01 -Name IAS -Number 12 -IssueDate 2019-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2017-en-b&anchor=para_81_ab&doctype=Standard&forcepdf=true -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2021-01-01 -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2017-en-b&anchor=para_90&doctype=Standard&forcepdf=true -URIDate 2019-03-27 + Details
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- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to cash flow hedges. [Refer: Cash flow hedges [member]; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2019-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2019-en-r&anchor=para_81_ab&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_90&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of income tax relating to amounts recognised in other comprehensive income. [Refer: Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2019-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2019-en-r&anchor=para_81_ab&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_90&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to exchange differences on the translation of financial statements of foreign operations. [Refer: Other comprehensive income; Reserve of exchange differences on translation] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2019-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2019-en-r&anchor=para_81_ab&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_90&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to financial assets measured at fair value through other comprehensive income. [Refer: Financial assets measured at fair value through other comprehensive income; Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2019-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2019-en-r&anchor=para_81_ab&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_90&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of income tax relating to amounts recognised in other comprehensive income in relation to remeasurements of defined benefit plans. [Refer: Other comprehensive income; Reserve of remeasurements of defined benefit plans; Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2019-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2019-en-r&anchor=para_81_ab&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_90&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of income tax relating to an entity's share of other comprehensive income of associates and joint ventures accounted for using the equity method that will be reclassified to profit or loss. [Refer: Share of other comprehensive income of associates and joint ventures accounted for using equity method, before tax] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 91 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_91&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of income and expense (including reclassification adjustments) that is not recognised in profit or loss as required or permitted by IFRSs. [Refer: IFRSs [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 106 -Subparagraph d -Clause ii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_106_d_ii&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2019-01-01 -Paragraph B12 -Subparagraph b -Clause viii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2019-en-r&anchor=para_B12_b_viii&doctype=Appendix&subtype=B -URIDate 2019-03-27 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 81A -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_81A_b&doctype=Standard -URIDate 2019-03-27 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 91 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_91_a&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of other comprehensive income, before tax, related to cash flow hedges. [Refer: Cash flow hedges [member]; Other comprehensive income, before tax] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 91 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_91_b&doctype=Standard -URIDate 2019-03-27 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 7 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_7&doctype=Standard -URIDate 2019-03-27 + Details
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