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Business Combination - Summary of Operating Income And Net Profit And Loss Before Elimination Of Intercompany Transactions Of The Acquired Companies (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Disclosure of Business Combination Operating Income And Net Profit Loss Before Elimination Of Inter Company Transaction Detailed Information Explanatory [Line Items] |  |  |
Operating revenue | ₩ 25,205,659 | ₩ 24,440,647 | ₩ 24,899,189
Profit (loss) for the year | 1,459,395 | ₩ 746,256 | ₩ 695,868
HCN Co.,Ltd [Member] |  |  |
Disclosure of Business Combination Operating Income And Net Profit Loss Before Elimination Of Inter Company Transaction Detailed Information Explanatory [Line Items] |  |  |
Operating revenue | 248,636 |  |
Profit (loss) for the year | 21,821 |  |
HCN Co.,Ltd [Member] | After Business Combination [Member] |  |  |
Disclosure of Business Combination Operating Income And Net Profit Loss Before Elimination Of Inter Company Transaction Detailed Information Explanatory [Line Items] |  |  |
Operating revenue | 63,682 |  |
Profit (loss) for the year | 7,882 |  |
Epsilon Global Communications Pte. Ltd [Member] |  |  |
Disclosure of Business Combination Operating Income And Net Profit Loss Before Elimination Of Inter Company Transaction Detailed Information Explanatory [Line Items] |  |  |
Operating revenue | 60,178 |  |
Profit (loss) for the year | (12,592) |  |
Epsilon Global Communications Pte. Ltd [Member] | After Business Combination [Member] |  |  |
Disclosure of Business Combination Operating Income And Net Profit Loss Before Elimination Of Inter Company Transaction Detailed Information Explanatory [Line Items] |  |  |
Operating revenue | 15,670 |  |
Profit (loss) for the year | ₩ (2,866) |  |

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