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Intangible Assets - Summary of Intangible Assets (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | ₩ 2,834,037 | ₩ 3,407,124 |
Changes in accounting policy |  | (26,207) |
Acquisition and capital expenditure | 165,630 | 178,694 |
Disposal and termination | (13,820) | (15,679) |
Amortization | (628,154) | (660,705) | ₩ (629,526)
Impairment | (211,637) | (61,898) |
Changes in scope of consolidation | 4,342 |  |
Others | 10,860 | 12,708 |
Ending, net | 2,161,258 | 2,834,037 | 3,407,124
Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 7,996,482 | 8,064,270 |
Ending, net | 7,898,325 | 7,996,482 | 8,064,270
Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (5,162,445) | (4,657,146) |
Ending, net | (5,737,067) | (5,162,445) | (4,657,146)
Goodwill [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 235,570 | 236,058 |
Impairment |  | (605) |
Others | (5,485) | 117 |
Ending, net | 230,085 | 235,570 | 236,058
Goodwill [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 541,596 | 542,074 |
Ending, net | 536,093 | 541,596 | 542,074
Goodwill [member] | Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (306,026) | (306,016) |
Ending, net | (306,008) | (306,026) | (306,016)
Development costs [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 272,634 | 335,110 |
Acquisition and capital expenditure | 26,990 | 47,903 |
Disposal and termination | (1,849) | (3,019) |
Amortization | (104,938) | (115,839) |
Impairment |  | (1,333) |
Changes in scope of consolidation | 575 |  |
Others | 87,587 | 9,812 |
Ending, net | 280,999 | 272,634 | 335,110
Development costs [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 1,661,372 | 1,680,372 |
Ending, net | 1,767,422 | 1,661,372 | 1,680,372
Development costs [member] | Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (1,388,738) | (1,345,262) |
Ending, net | (1,486,423) | (1,388,738) | (1,345,262)
Software [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 137,381 | 65,944 |
Acquisition and capital expenditure | 37,077 | 30,965 |
Disposal and termination | (105) | (1,267) |
Amortization | (54,191) | (68,222) |
Impairment | (1,776) | (1,807) |
Changes in scope of consolidation | 77 |  |
Others | 27,537 | 11,768 |
Ending, net | 146,000 | 137,381 | 65,944
Software [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 978,139 | 947,312 |
Ending, net | 1,053,980 | 978,139 | 947,312
Software [member] | Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (840,758) | (781,368) |
Ending, net | (907,980) | (840,758) | (781,368)
Frequency usage rights [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 1,753,941 | 2,156,500 |
Disposal and termination | 0 | (284) |
Amortization | (399,348) | (399,382) |
Impairment | (193,194) | (3,035) |
Others | (736) | 142 |
Ending, net | 1,160,663 | 1,753,941 | 2,156,500
Frequency usage rights [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 3,622,327 | 3,641,231 |
Ending, net | 3,373,095 | 3,622,327 | 3,641,231
Frequency usage rights [member] | Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (1,868,386) | (1,484,731) |
Ending, net | (2,212,432) | (1,868,386) | (1,484,731)
Others [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 434,511 | 513,512 |
Changes in accounting policy |  | (26,207) |
Acquisition and capital expenditure | 101,563 | 99,826 |
Disposal and termination | (11,866) | (11,109) |
Amortization | (69,677) | (77,262) |
Impairment | (16,667) | (55,118) |
Changes in scope of consolidation | 3,690 |  |
Others | (98,043) | (9,131) |
Ending, net | 343,511 | 434,511 | 513,512
Others [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 1,193,048 | 1,253,281 |
Ending, net | 1,167,735 | 1,193,048 | 1,253,281
Others [member] | Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (758,537) | (739,769) |
Ending, net | ₩ (824,224) | ₩ (758,537) | ₩ (739,769)

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