Commitments and contingencies Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 4,757,304	$ 4,632,105
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	22,726	21,427
Deferred standby letter of credit fees [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	232	155
Obligation to Repurchase Receivables Sold [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 147,782	$ 153,850