RETIREMENT AND POSTRETIREMENT PLANS - Net periodic benefit (credit) cost for the Employee Retirement Plan (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
BNB Bank Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 175	$ 267	$ 525	$ 802
Interest cost	$ 330	$ 195	$ 990	$ 585
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other	Other	Other
Expected return on assets	$ (687)	$ (857)	$ (2,062)	$ (2,572)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other	Other	Other
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other	Other	Other
Net periodic credit	$ (182)	$ (395)	$ (547)	$ (1,185)
Employee Retirement Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	$ 222	$ 155	$ 667	$ 465
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other	Other	Other
Expected return on assets	$ (382)	$ (490)	$ (1,147)	$ (1,470)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other	Other	Other
Amortization of unrealized loss	$ 147	$ 63	$ 442	$ 188
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other	Other	Other	Other
Net periodic credit	$ (13)	$ (272)	$ (38)	$ (817)
Retirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Contributions to the BNB Bank Pension Plan or the Employee Retirement Plan			$ 0