RETIREMENT AND POSTRETIREMENT PLANS - Weighted average allocation by asset category (Details)	Dec. 31, 2023	Dec. 31, 2022
Employee Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Actual Asset category	100.00%	100.00%
Employee Retirement Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual Asset category		51.00%
Employee Retirement Plan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Actual Asset category	100.00%	47.00%
Employee Retirement Plan | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Actual Asset category		2.00%
BNB Bank Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Actual Asset category	100.00%	100.00%
BNB Bank Pension Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Actual Asset category		51.00%
BNB Bank Pension Plan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Actual Asset category	99.00%	46.00%
BNB Bank Pension Plan | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Actual Asset category	1.00%	3.00%