Fair value measurement - Gains and losses (realized and unrealized) included in earnings for level 3 assets and liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	$ (11,904)	$ (11,631)	$ 9,336
Changes in unrealized gains (losses) included in earnings relating to assets still held	(2,112)	(512)	11,943
Mortgage banking activities
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	(11,370)	(11,589)	166
Changes in unrealized gains (losses) included in earnings relating to assets still held	(2,120)	(529)	11,964
Trading account profit (loss)
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	(34)	(42)	(71)
Changes in unrealized gains (losses) included in earnings relating to assets still held	8	17	(21)
Other operating income
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	0	0	9,241
Changes in unrealized gains (losses) included in earnings relating to assets still held	0	0	0
Provision for credit losses
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	(500)	0	0
Changes in unrealized gains (losses) included in earnings relating to assets still held	$ 0	$ 0	$ 0