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Segment Information - Summary of Segment Information (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | ₩ 23,546,929 | ₩ 23,120,878 | ₩ 22,699,856
Operating income (loss) | 1,069,092 | 1,339,780 | 1,077,068
Depreciation and Amortization | 3,364,502 | 3,345,266 | 3,338,598
Operating segments [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 27,217,843 | 26,699,112 | 26,427,216
Operating income (loss) | 1,112,554 | 1,378,653 | 1,096,256
Depreciation and Amortization | 3,356,126 | 3,337,353 | 3,333,984
Operating segments [member] | Marketing/Customer [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 16,242,552 | 16,144,415 | 16,130,454
Operating income (loss) | 1,018,593 | 1,050,053 | 816,679
Depreciation and Amortization | 2,895,930 | 2,870,161 | 2,897,876
Operating segments [member] | Finance [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 3,637,917 | 3,577,549 | 3,512,721
Operating income (loss) | 205,678 | 208,566 | 281,477
Depreciation and Amortization | 28,827 | 28,868 | 25,466
Operating segments [member] | Satellite TV [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 685,822 | 668,945 | 668,521
Operating income (loss) | 75,373 | 79,987 | 97,701
Depreciation and Amortization | 99,216 | 98,895 | 95,951
Operating segments [member] | All other segments [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 6,651,552 | 6,308,203 | 6,115,520
Operating income (loss) | (187,090) | 40,047 | (99,601)
Depreciation and Amortization | 332,153 | 339,429 | 314,691
Elimination [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | (3,670,914) | (3,578,234) | (3,727,360)
Operating income (loss) | (43,462) | (38,873) | (19,188)
Depreciation and Amortization | ₩ 8,376 | ₩ 7,913 | ₩ 4,614

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