Loans, net and allowance for credit losses - Major Classifications of Loans Outstanding (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable
Loans		$ 2,730,116
Loans	$ 2,849,897
Commercial
Accounts, Notes, Loans and Financing Receivable
Loans		433,048
Loans	368,411
Taxable
Accounts, Notes, Loans and Financing Receivable
Loans		433,048
Loans	368,411
Non-taxable
Accounts, Notes, Loans and Financing Receivable
Loans		166,210
Loans	175,304
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable
Loans		599,258
Loans	543,715
Municipal
Accounts, Notes, Loans and Financing Receivable
Loans		166,210
Loans	175,304
Real estate
Accounts, Notes, Loans and Financing Receivable
Loans		2,040,555
Loans	2,223,921
Commercial real estate
Accounts, Notes, Loans and Financing Receivable
Loans		1,709,827
Loans	1,863,118
Residential real estate
Accounts, Notes, Loans and Financing Receivable
Loans		330,728
Loans	360,803
Consumer
Accounts, Notes, Loans and Financing Receivable
Loans		90,303
Loans	82,261
Indirect Auto
Accounts, Notes, Loans and Financing Receivable
Loans		76,461
Loans	75,389
Consumer Other
Accounts, Notes, Loans and Financing Receivable
Loans		$ 13,842
Loans	$ 6,872