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Deferred Income Tax and Income Tax Expense - Summary of Movement in Deferred Income Tax Assets and Liabilities (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | ₩ (379,830) | ₩ (388,560) |
Statements of profit or loss | 110,609 | 16,827 | ₩ (169,961)
Other comprehensive income | 29,171 | (8,097) |
Ending | (240,050) | (379,830) | (388,560)
Deferred tax liabilities investment in subsidiaries associates and joint ventures [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (270,230) | (255,184) |
Statements of profit or loss | 730 | (7,821) |
Other comprehensive income | (1,194) | (7,225) |
Ending | (270,694) | (270,230) | (255,184)
Deferred tax liabilities depreciation and impairment loss [Member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (112,124) | (151,433) |
Statements of profit or loss | 9,797 | 39,309 |
Other comprehensive income | 0 | 0 |
Ending | (102,327) | (112,124) | (151,433)
Deferred tax liabilities plan assets [Member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (533,707) | (542,900) |
Statements of profit or loss | 71,001 | 8,367 |
Other comprehensive income | 590 | 826 |
Ending | (462,116) | (533,707) | (542,900)
Deferred tax liabilities advanced depreciation provision [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (518,080) | (521,939) |
Statements of profit or loss | (5,128) | 3,859 |
Other comprehensive income | 0 | 0 |
Ending | (523,208) | (518,080) | (521,939)
Deferred tax liabilities contract assets [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (421,824) | (424,302) |
Statements of profit or loss | 4,301 | 2,478 |
Other comprehensive income | 0 | 0 |
Ending | (417,523) | (421,824) | (424,302)
Deferred tax liabilities financial assets at fair value through profit or loss [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | 84 | (420) |
Statements of profit or loss | 7,233 | 461 |
Other comprehensive income | 0 | 43 |
Ending | 7,317 | 84 | (420)
Deferred tax liabilities Financial assets at fair value through other comprehensive income [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (102,627) | (60,629) |
Statements of profit or loss | 14,656 | (53) |
Other comprehensive income | (1,932) | (41,945) |
Ending | (89,903) | (102,627) | (60,629)
Other deferred tax liabilities [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (649,655) | (738,153) |
Statements of profit or loss | (113,707) | 90,876 |
Other comprehensive income | (12,034) | (2,378) |
Ending | (775,396) | (649,655) | (738,153)
Deferred tax liabilities [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (2,608,163) | (2,694,960) |
Statements of profit or loss | (11,117) | 137,476 |
Other comprehensive income | (14,570) | (50,679) |
Ending | (2,633,850) | (2,608,163) | (2,694,960)
Deferred tax assets depreciation and impairment loss [Member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | 116,746 | 188,832 |
Statements of profit or loss | (10,711) | (71,689) |
Other comprehensive income | 0 | (397) |
Ending | 106,035 | 116,746 | 188,832
Deferred tax assets contract liabilities [Member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | 111,978 | 121,289 |
Statements of profit or loss | (2,429) | (9,311) |
Other comprehensive income | 0 | 0 |
Ending | 109,549 | 111,978 | 121,289
Deferred tax assets defined benefit liabilities [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | 515,991 | 481,858 |
Statements of profit or loss | (66,182) | (6,705) |
Other comprehensive income | 42,110 | 40,838 |
Ending | 491,919 | 515,991 | 481,858
Deferred tax assets provisions [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | 146,171 | 151,955 |
Statements of profit or loss | 20,394 | (5,784) |
Other comprehensive income | 0 | 0 |
Ending | 166,565 | 146,171 | 151,955
Other deferred tax assets [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | 1,208,177 | 1,259,495 |
Statements of profit or loss | 165,310 | (53,459) |
Other comprehensive income | 1,631 | 2,141 |
Ending | 1,375,118 | 1,208,177 | 1,259,495
Deferred tax assets [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | 2,099,063 | 2,203,429 |
Statements of profit or loss | 106,382 | (146,948) |
Other comprehensive income | 43,741 | 42,582 |
Ending | 2,249,186 | 2,099,063 | 2,203,429
Temporary differences [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | (509,100) | (491,531) |
Statements of profit or loss | 95,265 | (9,472) |
Other comprehensive income | 29,171 | (8,097) |
Ending | (384,664) | (509,100) | (491,531)
Deferred tax assets tax credit carry forwards [member] |  |  |
Disclosure of temporary difference, unused tax losses and unused tax credits [Line Items] |  |  |
Beginning | 129,270 | 102,971 |
Statements of profit or loss | 15,344 | 26,299 |
Other comprehensive income | 0 | 0 |
Ending | ₩ 144,614 | ₩ 129,270 | ₩ 102,971

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