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Segment Information - Summary of Segment Information (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | ₩ 24,440,647 | ₩ 24,899,189 | ₩ 23,436,050
Operating income (loss) | 1,022,333 | 1,026,970 | 1,100,860
Depreciation and Amortization | 3,634,284 | 3,629,492 | 3,281,732
Operating segments [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 28,612,919 | 28,863,426 | 27,346,281
Operating income (loss) | 1,175,172 | 1,080,040 | 1,201,682
Depreciation and Amortization | 3,718,122 | 3,709,297 | 3,274,768
Operating segments [member] | ICT [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 18,275,765 | 18,527,631 | 17,724,320
Operating income (loss) | 809,741 | 634,046 | 933,191
Depreciation and Amortization | 3,233,878 | 3,229,159 | 2,917,163
Operating segments [member] | Finance [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 3,686,430 | 3,795,185 | 3,771,681
Operating income (loss) | 85,008 | 158,235 | 148,440
Depreciation and Amortization | 53,098 | 27,852 | 22,580
Operating segments [member] | Satellite TV [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 706,631 | 694,637 | 690,821
Operating income (loss) | 71,345 | 69,357 | 66,735
Depreciation and Amortization | 84,931 | 94,992 | 98,310
Operating segments [member] | Others [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | 5,944,093 | 5,845,973 | 5,159,459
Operating income (loss) | 209,078 | 218,402 | 53,316
Depreciation and Amortization | 346,215 | 357,294 | 236,715
Elimination [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Operating revenues | (4,172,272) | (3,964,237) | (3,910,231)
Operating income (loss) | (152,839) | (53,070) | (100,822)
Depreciation and Amortization | ₩ (83,838) | ₩ (79,805) | ₩ 6,964

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