RETIREMENT AND POSTRETIREMENT PLANS - Net periodic benefit (credit) cost for the Employee Retirement Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other
BNB Bank Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 807	$ 893
Interest cost	793	609
Expected return on plan assets	(3,441)	(2,883)
Net periodic credit	(1,841)	(1,381)
Employee Retirement Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	622	562	$ 732
Expected return on plan assets	(1,949)	(1,846)	(1,713)
Amortization of unrealized loss	261	824	914
Net periodic credit	$ (1,066)	(460)	(67)
RETIREMENT PLANS | BMP and Outside Director Retirement Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		12	234
Amortization of unrealized loss			179
Net periodic credit		$ 1,555	413
POSTRETIREMENT PLANS
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost			42
Amortization of unrealized loss			(9)
Net periodic credit			$ 1,684