RETIREMENT AND POSTRETIREMENT PLANS - Net periodic benefit (credit) cost for the Employee Retirement Plan (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Employee Retirement Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	$ 210	$ 223
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other
Expected return on assets	$ (360)	$ (383)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Other
Amortization of unrealized loss	$ 203	$ 148
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other
Net periodic credit	$ 53	$ (12)
BNB Bank Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		175
Interest cost	310	330
Expected return on assets	$ (680)	$ (687)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other
Net periodic credit	$ (370)	$ (182)
Retirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Contributions to the BNB Bank Pension Plan or the Employee Retirement Plan	$ 0