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Financial Instruments by Category - Summary of Gains or Losses Arising From Financial Instruments by Category (Detail) - KRW (₩) ₩ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Disclosure of detailed information about financial instruments [line items] |  |  |
Interest income | ₩ 273,460 | ₩ 270,571 | ₩ 282,704
Interest expense | (263,389) | (263,579) | (278,427)
Total |  | (38,610) | 159,062
Other comprehensive income (loss) for the year | 165,567 | 23,255 | 172,338
Reclassified to profit or loss from other comprehensive income for the year | (136,583) | 111,431 |
Interest expense | (36,651) | (44,091) | (55,001)
Financial liabilities designated as at fair value through profit or loss [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Gain (loss) foreign currency transaction | (2) | 0 | 0
Gain (loss) on disposal | 2,136 | 799 | 2,664
Gain (loss) on valuation | 42,447 | 119 | (1,936)
Derivatives used for hedging [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Gain on transactions | (6,208) | 1,141 | 0
Gain (loss) on valuation | (7,206) | (161,003) | 4,949
Other comprehensive income (loss) for the year | (3,112) | (81,671) | 20,742
Reclassified to profit or loss from other comprehensive income for the year | 6,722 | 107,786 | (5,080)
Financial liabilities at amortized cost [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Interest expense | (232,197) | (220,945) | (223,974)
Gain (loss) foreign currency transaction | (3,580) | (10,717) | (20,958)
Gain (loss) on foreign currency translation | (201,623) | 141,849 | (75,502)
Total | 215,095 |  |
Lease liabilities [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Interest expense | (36,650) | (44,091) | (55,001)
Financial assets at amortized cost [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Interest income | 74,937 | 55,742 | 79,838
Gain (loss) foreign currency transaction | 12,826 | (19,244) | 32,293
Gain (loss) on foreign currency translation | 2,911 | (3,895) | (474)
Gain (loss) on disposal | 35 | 138 | (43)
Impairment loss | (110,286) | (140,474) | (59,947)
Financial assets at fair value through profit or loss [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Interest income | 3,673 | 6,548 | 5,634
Dividend income | 21,499 | 4,379 | 1,096
Gain (loss) foreign currency transaction | 17,794 |  | (27)
Gain (loss) on foreign currency translation |  | (38) |
Gain (loss) on disposal | 29,974 | (329) | 5,115
Gain (loss) on valuation | 64,659 | 59,044 | 4,334
Financial assets at fair value through other comprehensive income [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Interest income | 222,290 | 227,736 | 217,355
Dividend income | 1,365 | 56 | 2,312
Gain (loss) on disposal | (22,712) | (8,152) | (11,247)
Impairment loss |  |  | (304)
Other comprehensive income (loss) for the year | 129,780 | 41,997 | 167,152
Derivative financial liabilities [member] |  |  |
Disclosure of detailed information about financial instruments [line items] |  |  |
Gain on transactions | 0 | 6,050 | 6,332
Gain (loss) on valuation | 203,961 | (2,707) | 56,537
Other comprehensive income (loss) for the year | 144,967 | (2,373) | 46,806
Reclassified to profit or loss from other comprehensive income for the year | ₩ (143,305) | ₩ 3,645 | ₩ (39,604)

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