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Revenue from Contracts with Customers and Relevant Contract Assets and Liabilities - Detail explanation of Operating revenue (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Disclosure of disaggregation of revenue from contracts with customers [abstract] |  |  |
Mobile services | ₩ 6,805,218 | ₩ 6,795,124 | ₩ 6,827,685
Fixed-line services: | 4,827,015 | 4,866,698 | 4,869,253
Fixed-line and VoIP telephone services | 1,463,553 | 1,578,546 | 1,708,319
Broadband Internet access services | 2,256,188 | 2,177,447 | 2,112,763
Data communication services | 1,107,274 | 1,110,705 | 1,048,171
Media and content | 2,637,691 | 2,516,256 | 2,261,808
Financial services | 3,493,920 | 3,641,655 | 3,444,917
Sale of goods | 3,593,127 | 4,194,168 | 3,288,911
Others | 3,083,676 | 2,885,288 | 2,743,476
Operating revenue | ₩ 24,440,647 | ₩ 24,899,189 | ₩ 23,436,050

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- Definition The amount of revenue arising from the rendering of internet services. [Refer: Revenue] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_112_c&doctype=Standard -URIDate 2020-01-01 + Details
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