v3.26.1
Operating Segments - Segment Information (Detail) - KRW (₩)
₩ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of operating segments [line items]      
Revenue ₩ 17,099,213 ₩ 17,940,609 ₩ 17,608,511
Depreciation and amortization 3,467,134 3,560,374 3,614,766
Operating profit (loss) 1,048,501 1,690,862 1,756,276
Gain (loss) relating to investments in subsidiaries, associates and joint ventures, net (63,602) 321,787 10,928
Profit before income tax 722,261 1,761,765 1,488,179
Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 17,099,213 17,940,609 17,608,511
Depreciation and amortization 3,467,134 3,560,374 3,614,766
Operating profit (loss) 1,048,501 1,690,862 1,756,276
Finance income (costs), net (262,638) (250,884) (279,025)
Gain (loss) relating to investments in subsidiaries, associates and joint ventures, net (63,602) 321,787 10,928
Profit before income tax 722,261 1,761,765 1,488,179
External revenue [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 17,099,213 17,940,609 17,608,511
Operating segments [member]      
Disclosure of operating segments [line items]      
Operating profit (loss) 1,095,762 1,831,559 1,750,235
Operating segments [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 19,966,701 20,751,958 20,363,377
Depreciation and amortization 3,564,646 3,681,492 3,739,466
Operating profit (loss) 1,095,762 1,831,559 1,750,235
Operating segments [member] | Intersegment [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 2,867,488 2,811,349 2,754,866
Operating segments [member] | External revenue [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 17,099,213 17,940,609 17,608,511
Operating segments [member] | Cellular services [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 14,155,266 14,866,217 14,664,180
Depreciation and amortization 2,551,737 2,688,764 2,743,448
Operating profit (loss) 817,941 1,529,971 1,463,934
Operating segments [member] | Cellular services [member] | Intersegment [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 1,602,723 1,548,004 1,541,014
Operating segments [member] | Cellular services [member] | External revenue [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 12,552,543 13,318,213 13,123,166
Operating segments [member] | Fixed-line telecommunication services [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 5,421,288 5,271,705 5,095,704
Depreciation and amortization 993,930 966,904 971,628
Operating profit (loss) 308,372 366,517 329,072
Operating segments [member] | Fixed-line telecommunication services [member] | Intersegment [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 1,230,175 1,196,293 1,167,684
Operating segments [member] | Fixed-line telecommunication services [member] | External revenue [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 4,191,113 4,075,412 3,928,020
Operating segments [member] | Others [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 390,147 614,036 603,493
Depreciation and amortization 18,979 25,824 24,390
Operating profit (loss) (30,551) (64,929) (42,771)
Operating segments [member] | Others [member] | Intersegment [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 34,590 67,052 46,168
Operating segments [member] | Others [member] | External revenue [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue 355,557 546,984 557,325
Adjustments [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue [1] (2,867,488) (2,811,349) (2,754,866)
Depreciation and amortization [1] (97,512) (121,118) (124,700)
Operating profit (loss) [1] (47,261) (140,697) 6,041
Adjustments [member] | Intersegment [member] | Continuing Operations [member]      
Disclosure of operating segments [line items]      
Revenue [1] ₩ (2,867,488) ₩ (2,811,349) ₩ (2,754,866)
[1] Adjustments for operating profit (loss) are the amount differences from operating profit (loss) included in CODM report which is based on Korean IFRS to operating profit (loss) under IFRS. The reconciliation of these amounts is included in note 4-(2). Adjustments for depreciation and amortization and operating profit (loss) also included the amount due to the consolidation adjustments, such as internal transactions.