Fair value of financial assets and liabilities - Summary Of Changes in Deferred day 1 profits or losses (Details) - KRW (₩) ₩ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Reconciliation of aggregate difference between fair value at initial recognition and transaction price yet to be recognised in profit or loss [abstract]
Beginning balance	₩ 28	₩ 7,848	₩ 17,964
Changes in aggregate difference between fair value at initial recognition and transaction price yet to be recognised in profit or loss [abstract]
Amounts recognized in losses	(28)	(7,820)	(10,116)
Ending balance	₩ 0	₩ 28	₩ 7,848

The increase (decrease) in the aggregate difference between the fair value at initial recognition and the transaction price of financial instruments yet to be recognised in profit or loss resulting from amounts recognised in profit or loss. [Refer: Aggregate difference between fair value at initial recognition and transaction price yet to be recognised in profit or loss; Classes of financial instruments [domain]]

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