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Financial Instruments by Category - Summary of Gains or Losses Arising From Financial Instruments by Category (Parenthetical) (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Disclosure of detailed information about financial instruments [line items] |  |  |
Interest income recognized as operating revenue | ₩ 271,925 | ₩ 273,460 | ₩ 270,571
Interest expense recognized as operating expense | 293,854 | 263,389 | 263,579
Profit and loss from foreign currency transaction | 67,976 | 19,976 | 17,493
BC Card Co., Ltd. [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Interest income recognized as operating revenue | 68,869 | 27,440 | 20,854
Interest expense recognized as operating expense | 27,060 | 5,458 | 1,456
Profit and loss from foreign currency transaction | 3,569 | 2,373 | 19,687
Dividend income | 2,299 | 1,340 | 2,059
Gain (loss) on valuation | 7,860 | ₩ 15,459 | ₩ 40,822
Gain Loss On Valuation Of derivatives | ₩ 418 |  |

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