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Operating Expenses - Summary of Operating Expenses (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Profit (loss) [abstract] |  |  |
Salaries and wages | ₩ 4,123,680 | ₩ 3,974,233 | ₩ 3,845,842
Depreciation | 2,605,128 | 2,530,252 | 2,674,205
Depreciation of right-of-use assets | 404,175 | 442,629 |
Amortization of intangible assets | 624,982 | 656,611 | 607,527
Commissions | 965,461 | 1,115,477 | 1,080,168
Interconnection charges | 500,081 | 534,025 | 579,613
International interconnection fee | 172,529 | 240,254 | 226,627
Purchase of inventories | 3,681,801 | 4,453,820 | 4,414,094
Changes of inventories | 257,041 | 282,957 | (432,607)
Sales commission | 2,337,127 | 2,315,731 | 1,942,841
Service cost | 2,102,875 | 1,610,261 | 1,540,869
Utilities | 360,797 | 332,816 | 323,411
Taxes and dues | 283,197 | 277,742 | 285,131
Rent | 136,355 | 193,357 | 460,377
Insurance premium | 71,018 | 82,404 | 73,654
Installation fee | 132,117 | 155,178 | 143,669
Advertising expenses | 132,466 | 150,166 | 157,675
Research and development expenses | 156,940 | 165,028 | 176,758
Card service cost | 2,941,669 | 3,066,766 | 3,112,618
Others | 1,428,875 | 1,292,512 | 1,122,718
Total | ₩ 23,418,314 | ₩ 23,872,219 | ₩ 22,335,190

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- Definition The amount of depreciation expense. Depreciation is the systematic allocation of depreciable amounts of tangible assets over their useful lives. + 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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- Definition The amount of depreciation of right-of-use assets. [Refer: Depreciation and amortisation expense; Right-of-use assets] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 16 -IssueDate 2020-01-01 -Paragraph 53 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2020-en-r&anchor=para_53_a&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of expense relating to fees and commissions. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_85&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of expense arising from purchased insurance. + 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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- Definition The amount of miscellaneous other operating expenses. [Refer: Other operating income (expense)] + 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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- Definition The amount of all operating expenses. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_85&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The amount of expense recognised on rental activities. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 85 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_85&doctype=Standard -URIDate 2020-01-01 + Details
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