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Deferred Income Tax and Income Tax Expense - Summary of Tax on the Group's Profit Before Tax (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] |  |  |
Profit before income tax expense | ₩ 816,997 | ₩ 1,123,431 | ₩ 710,741
Statutory income tax expense | 197,251 | 271,870 | 171,999
Tax effect |  |  |
Income not taxable for taxation purposes | (19,268) | (28,093) | (21,881)
Non-deductible expenses | 39,746 | 21,947 | 28,849
Tax credit | (27,211) | (13,764) | (9,660)
Additional payment of income taxes | 976 | (4,780) | 997
Tax effect and adjustment on consolidation |  |  |
Goodwill impairment | 20,475 | 31,847 | 23,185
Eliminated dividend income form subsidiaries | 34,305 | 40,087 | 20,452
Changes of out-side tax effect | 17,990 | (567) | 9,844
Others | 6,392 | 9,767 | 3,346
Income tax expense | ₩ 270,656 | ₩ 328,314 | ₩ 227,131

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- Definition The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax that relate to continuing operations. [Refer: Continuing operations [member]; Current tax expense (income); Deferred tax expense (income)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 8 -IssueDate 2017-01-01 -Paragraph 23 -Subparagraph h -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2017-03-01&anchor=para_23_h&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 26 -IssueDate 2017-01-01 -Paragraph 35 -Subparagraph b -Clause viii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=26&date=2017-03-01&anchor=para_35_b_viii&doctype=Standard -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 79 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_79&doctype=Standard -URIDate 2017-03-09 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 81 -Subparagraph c -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_c_i&doctype=Standard -URIDate 2017-03-09 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 82 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_82_d&doctype=Standard -URIDate 2017-03-09 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2017-01-01 -Paragraph 81 -Subparagraph c -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_c_ii&doctype=Standard -URIDate 2017-03-09 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 12 -IssueDate 2017-01-01 -Paragraph B13 -Subparagraph g -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_B13_g&doctype=Appendix&seq=2 -URIDate 2017-03-09 + Details
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