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
	Mar. 31, 2024	Mar. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	$ (3,940)	$ (1,385)
Changes in unrealized gains (losses) included in earnings relating to assets still held	(1,700)	1,295
Mortgage banking activities
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	(3,439)	(1,376)
Changes in unrealized gains (losses) included in earnings relating to assets still held	(1,202)	1,286
Trading account (loss) profit
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	(1)	(9)
Changes in unrealized gains (losses) included in earnings relating to assets still held	2	9
Provision for credit losses
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Gain (loss) included in earnings	(500)	0
Changes in unrealized gains (losses) included in earnings relating to assets still held	$ (500)	$ 0