Securities - Contractual maturities of debt securities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Amortized Cost
Due in one year or less	$ 8,011
Due after one but within five years	45,357
Due after five but within ten years	93,979
Due after ten years	406,781
Total of securities having specified maturity period	554,128
Mortgage-backed securities and collateralized mortgage obligations	915,275
Amortized Cost	1,469,403	$ 1,498,626
Fair Value
Due in one year or less	7,959
Due after one but within five years	43,379
Due after five but within ten years	88,146
Due after ten years	365,304
Total of securities having specified maturities period	504,788
Mortgage-backed securities and collateralized mortgage obligations	794,438
TOTAL	$ 1,299,226	$ 1,330,481