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Intangible Assets - Summary of Intangible Assets (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | ₩ 3,407,124 | ₩ 2,632,703 |
Changes in accounting policy | (26,207) |  |
Acquisition and capital expenditure | 178,694 | 1,331,172 |
Disposal and termination | (15,679) | (15,417) |
Amortization | (660,705) | (629,526) | ₩ (635,150)
Impairment | (61,898) | (12,996) |
Inclusion in scope of consolidation |  | 93,719 |
Others | 12,708 | 7,468 |
Ending, net | 2,834,037 | 3,407,123 |
Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 8,064,270 | 6,714,013 |
Ending, net | 7,996,482 | 8,064,270 |
Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (4,657,146) | (4,081,310) |
Ending, net | (5,162,445) | (4,657,147) |
Goodwill [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 236,058 | 168,880 |
Impairment | (605) | (518) |
Inclusion in scope of consolidation |  | 67,696 |
Others | 117 |  |
Ending, net | 235,570 | 236,058 |
Goodwill [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 542,074 | 474,908 |
Ending, net | 541,596 | 542,074 |
Goodwill [member] | Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (306,016) | (306,028) |
Ending, net | (306,026) | (306,016) |
Development costs [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 335,110 | 418,559 |
Acquisition and capital expenditure | 47,903 | 56,670 |
Disposal and termination | (3,019) | (3,436) |
Amortization | (115,839) | (147,304) |
Impairment | (1,333) |  |
Others | 9,812 | 10,621 |
Ending, net | 272,634 | 335,110 |
Development costs [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 1,680,372 | 1,643,886 |
Ending, net | 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 | (1,345,262) | (1,225,327) |
Ending, net | (1,388,738) | (1,345,262) |
Software [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 165,944 | 190,241 |
Acquisition and capital expenditure | 30,965 | 29,800 |
Disposal and termination | (1,267) | (736) |
Amortization | (68,222) | (72,185) |
Impairment | (1,807) | (222) |
Inclusion in scope of consolidation |  | 2,073 |
Others | 11,768 | 16,973 |
Ending, net | 137,381 | 165,944 |
Software [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 947,312 | 893,500 |
Ending, net | 978,139 | 947,312 |
Software [member] | Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (781,368) | (703,259) |
Ending, net | (840,758) | (781,368) |
Frequency usage rights [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 2,156,500 | 1,364,942 |
Acquisition and capital expenditure |  | 1,110,865 |
Disposal and termination | (284) | (558) |
Amortization | (399,382) | (318,815) |
Impairment | (3,035) |  |
Others | 142 | 66 |
Ending, net | 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 | 3,641,231 | 2,530,341 |
Ending, net | 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 | (1,484,731) | (1,165,399) |
Ending, net | (1,868,386) | (1,484,731) |
Others [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 513,512 | 490,081 |
Changes in accounting policy | (26,207) |  |
Acquisition and capital expenditure | 99,826 | 133,837 |
Disposal and termination | (11,109) | (10,687) |
Amortization | (77,262) | (91,222) |
Impairment | (55,118) | (12,256) |
Inclusion in scope of consolidation |  | 23,950 |
Others | (9,131) | (20,192) |
Ending, net | 434,511 | 513,511 |
Others [member] | Gross carrying amount [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | 1,253,281 | 1,171,378 |
Ending, net | 1,193,048 | 1,253,281 |
Others [member] | Accumulated depreciation and amortisation [member] |  |  |
Disclosure of detailed information about intangible assets [line items] |  |  |
Beginning, net | (739,769) | (681,297) |
Ending, net | ₩ (758,537) | ₩ (739,770) |

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