Fair value measurement - Gains and losses (realized and unrealized) included in earnings for level 3 assets and liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gains (Losses) included in earnings	$ (2,796)	$ 8,732	$ (10,407)	$ 11,990
Changes in unrealized gains (losses) included in earnings relating to assets still held	(377)	1,990	(1,807)	11,568
Mortgage banking activities
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gains (Losses) included in earnings	(2,793)	(499)	(10,386)	2,776
Changes in unrealized gains (losses) included in earnings relating to assets still held	(381)	1,984	(1,828)	11,556
Trading account (loss) profit
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gains (Losses) included in earnings	(3)	(10)	(21)	(27)
Changes in unrealized gains (losses) included in earnings relating to assets still held	$ 4	6	$ 21	12
Other operating income
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gains (Losses) included in earnings		9,241		9,241
Changes in unrealized gains (losses) included in earnings relating to assets still held		$ 0		$ 0