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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, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Deferred tax assets and liabilities [abstract] |  |  |
Available-for-sale valuation gain(loss), Before recognition | ₩ (5,561) | ₩ 9,347 | ₩ (47,515)
Hedge instruments valuation gain(loss), Before recognition | 40,694 | (14,611) | 18,406
Remeasurements from net defined benefit liabilities, Before recognition | (110,768) | 5,558 | (49,963)
Shares of gain(loss) of associates and joint ventures, Before recognition | 13,410 | (641) | (5,297)
Foreign currency translation adjustment | (27,865) | (7,133) | (6,443)
Total, Before recognition | (90,090) | (7,480) | (90,812)
Available-for-sale valuation gain(loss), Tax effect | 1,346 | (2,262) | 11,499
Hedge instruments valuation gain(loss), Tax effect | (9,848) | 3,536 | (4,454)
Remeasurements from net defined benefit liabilities, Tax effect | 26,806 | (1,345) | 12,091
Shares of gain(loss) of associates and joint ventures, Tax effect | (3,245) | 155 | 1,282
Foreign currency translation adjustment | 6,743 | 1,726 | 1,559
Total, Tax effect | 21,802 | 1,810 | 21,977
Available-for-sale valuation gain(loss), After recognition | (4,215) | 7,085 | (36,016)
Hedge instruments valuation gain(loss), After recognition | 30,846 | (11,075) | 13,952
Remeasurements from net defined benefit liabilities, After recognition | (83,962) | 4,213 | (37,872)
Shares of gain(loss) of associates and joint ventures, After recognition | 10,165 | (486) | (4,015)
Foreign currency translation adjustment | (21,122) | (5,407) | (4,884)
Total other comprehensive loss | ₩ (68,288) | ₩ (5,670) | ₩ (68,835)

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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 2018-01-01 -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-02&anchor=para_81_ab&doctype=Standard&book=B -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2018-01-01 -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-02&anchor=para_90&doctype=Standard&book=B -URIDate 2017-03-09 + 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 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_ab&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_90&doctype=Standard -URIDate 2017-03-09 + 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 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_ab&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_90&doctype=Standard -URIDate 2017-03-09 + 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 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_ab&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_90&doctype=Standard -URIDate 2017-03-09 + 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 2017-01-01 -Paragraph 81 -Subparagraph ab -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_ab&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 90 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_90&doctype=Standard -URIDate 2017-03-09 + 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 2017-01-01 -Paragraph 91 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91&doctype=Standard -URIDate 2017-03-09 + 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 2017-01-01 -Paragraph 106 -Subparagraph d -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d_ii&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2017-01-01 -Paragraph B12 -Subparagraph b -Clause viii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_B12_b_viii&doctype=Appendix&seq=2 -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 81A -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_81A_b&doctype=Standard -URIDate 2017-03-09 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 91 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_a&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of other comprehensive income, before tax. [Refer: Other comprehensive income] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 91 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_b&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of other comprehensive income, before tax, related to available-for-sale financial assets. [Refer: Financial assets available-for-sale; Other comprehensive income, before tax] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2018-01-01 -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 91 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-02&anchor=para_91_b&doctype=Standard&book=B -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2018-01-01 -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 7 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-02&anchor=para_7&doctype=Standard&book=B -URIDate 2017-03-09 + 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 2017-01-01 -Paragraph 91 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_b&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 7 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_7&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of other comprehensive income, before tax, related to exchange differences on translation of financial statements of foreign operations. [Refer: Other comprehensive income, before tax] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 91 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_91_b&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 7 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_7&doctype=Standard -URIDate 2017-03-09 + Details
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