Investment Securities - Amortized cost and estimated fair value (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Carrying Value
Due within one year or less	$ 4,819
Due after one year through five years	34,896
Due after five years through ten years	74,002
Due after 10 years	238,344
Total investment securities	352,061
Estimated Fair Value
Due within one year or less	4,817
Due after one year through five years	34,769
Due after five years through ten years	74,581
Due after 10 years	235,510
Total investment securities	349,677
Amortized Cost
Due within one year or less	2
Due after one year through five years	2,809
Due after five years through ten years	96,263
Due after 10 years	761,184
Total investment securities available-for-sale	860,258
Fair Value
Due within one year or less	2
Due after one year through five years	2,883
Due after five years through ten years	99,243
Due after 10 years	751,521
Total investment securities available-for-sale	$ 853,649