INVESTMENT SECURITIES - Investments classified by contractual maturity date (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Available-for-Sale - Amortized Cost
After three through four years	$ 245
After four through five years	960
After five through fifteen years	10,726
After fifteen years	47,078
Securities not due on a single maturity date	467,226
Available-for-sale securities, Amortized Cost, Total	526,235	$ 531,892
Available-for-Sale - Fair Value
After three through four years	245
After four through five years	974
After five through fifteen years	10,534
After fifteen years	45,230
Securities not due on a single maturity date	408,325
Available-for-sale securities, Fair Value, Total	465,308	478,207
Held-to-Maturity - Amortized Carrying Value
After five through fifteen years	3,247
After fifteen years	2,932
Securities not due on a single maturity date	187,187
Held-to-Maturity, Amortized Carrying Value, Total	193,366	195,023
Held-to-Maturity - Fair Value
After five through fifteen years	2,931
After fifteen years	2,667
Securities not due on a single maturity date	162,158
Held-to-maturity, Fair Value, Total	$ 167,756	$ 171,193