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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, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Deferred tax assets and liabilities [abstract] |  |  |
Profit before income tax expense | ₩ 1,019,334 | ₩ 1,033,977 | ₩ 816,997
Statutory income tax expense | 269,955 | 273,982 | 197,251
Tax effect |  |  |
Income not taxable for taxation purposes | (1,265) | (85,322) | (19,268)
Non-deductible expenses | 19,543 | 18,126 | 39,746
Tax credit | (39,190) | (20,319) | (27,211)
Additional payment of income taxes | 3,832 | 11,439 | 976
Tax effect and adjustment on consolidation |  |  |
Goodwill impairment | 159 | 137 | 20,475
Eliminated dividend income form subsidiaries | 21,917 | 31,966 | 34,305
Changes of out-side tax effect | 13,539 | 618 | 17,990
Tax effect of investment in kind |  | 82,820 |
Intangible Asset impairment and amortization | 14,052 |  |
Reversal expenses of contract cost assets | 11,213 |  |
Others | 6,305 | 1,118 | 6,392
Income tax expense | ₩ 320,060 | ₩ 314,565 | ₩ 270,656

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