RETIREMENT AND POSTRETIREMENT PLANS - Change in Accumulated Other Comprehensive Loss from Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Gain (loss) recognized during the year	$ 190	$ 2,062	$ (6,563)
Curtailment credit			(1,543)
Accumulated other comprehensive loss, net of deferred taxes	(91,579)	(94,379)
Employee Retirement Plan
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Balance at beginning of period	(5,323)	(4,097)
Amortization of unrealized loss	572	261
Gain (loss) recognized during the year	(1,612)	(1,487)
Balance at the end of the period	(6,363)	(5,323)	(4,097)
Accumulated other comprehensive loss, net of deferred taxes	4,343	3,649
BNB Bank Pension Plan
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Balance at beginning of period	(2,358)	2,193
Gain (loss) recognized during the year	(698)	(4,551)
Balance at the end of the period	(3,056)	(2,358)	2,193
Accumulated other comprehensive loss, net of deferred taxes	$ 2,087	$ 1,617
Retirement Plans | BMP and Outside Director Retirement Plan
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Balance at beginning of period			(1,820)
Gain (loss) recognized during the year			277
Curtailment credit			$ 1,543