Securities - Contractual maturities of debt securities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 8,441
Due after one but within five years	43,678
Due after five but within ten years	92,137
Due after ten years	411,652
Total of securities having specified maturity period	555,908
Mortgage-backed securities and collateralized mortgage obligations	934,439
Amortized Cost	1,490,347	$ 1,498,626
Fair Value
Due in one year or less	8,406
Due after one but within five years	42,314
Due after five but within ten years	87,646
Due after ten years	373,302
Total of securities having specified maturities period	511,668
Mortgage-backed securities and collateralized mortgage obligations	829,113
TOTAL	$ 1,340,781	$ 1,330,481