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, 2025	Mar. 31, 2024
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Total gains (losses) included in earnings	$ (3,576)	$ (3,940)
Changes in unrealized gains (losses) relating to assets still held at reporting date	(1,316)	(1,700)
Mortgage banking activities
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Total gains (losses) included in earnings	(3,570)	(3,439)
Changes in unrealized gains (losses) relating to assets still held at reporting date	(1,325)	(1,202)
Trading account profit (loss)
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Total gains (losses) included in earnings	(6)	(1)
Changes in unrealized gains (losses) relating to assets still held at reporting date	9	2
Provision for credit losses
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Abstract
Total gains (losses) included in earnings	0	(500)
Changes in unrealized gains (losses) relating to assets still held at reporting date	$ 0	$ (500)