INVESTMENT SECURITIES - Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Available-for-Sale - Amortized cost
After four through five years	$ 2,292
After five through fifteen years	13,081
After fifteen years	25,831
Securities not due on a single maturity date	434,510
Available-for-sale Securities, Amortized Cost Basis, Total	475,714
Available-for-Sale - Fair Value
After four through five years	2,318
After five through fifteen years	13,208
After fifteen years	25,474
Securities not due on a single maturity date	420,375
Available-for-sale Securities, Total	461,375	$ 501,032
Held-to-Maturity - Amortized Carrying Value
After five through fifteen years	2,575
After fifteen years	3,681
Securities not due on a single maturity date	221,185
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss, Total	227,441
Held-to-Maturity - Fair Value
After five through fifteen years	2,440
After fifteen years	3,553
Securities not due on a single maturity date	214,195
Held-to-maturity Fair Value, Total	$ 220,188