PENSION AND OTHER POSTRETIREMENT PLANS - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity Securities
Defined Benefit Plan Disclosure
Defined Benefit Plans Target Allocation Percentage	60.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	8.85%
Debt Securities
Defined Benefit Plan Disclosure
Defined Benefit Plans Target Allocation Percentage	40.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	3.00%
Pension Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Accumulated Benefit Obligation		$ 2,700,000
Assets for Plan Benefits, Defined Benefit Plan	$ 2,346,000	$ 2,470,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	6.50%	6.50%	6.50%
Defined Benefit Plan, Expected Amortization, Next Fiscal Year	$ 160,000
Defined Benefit Plan, Plan Assets, Contributions by Employer		$ 27,000
Pension Benefits | Equity Securities
Defined Benefit Plan Disclosure
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	8.85%
Pension Benefits | Debt Securities
Defined Benefit Plan Disclosure
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	3.00%
SERP Benefits
Defined Benefit Plan Disclosure
Defined Benefit Plan, Accumulated Benefit Obligation	$ 1,000,000.0
Assets for Plan Benefits, Defined Benefit Plan	$ 878,000	$ 913,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	6.50%	6.50%	6.50%
Defined Benefit Plan, Expected Amortization, Next Fiscal Year	$ 82,000
SERP Benefits | Equity Securities
Defined Benefit Plan Disclosure
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	8.85%
SERP Benefits | Debt Securities
Defined Benefit Plan Disclosure
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	3.00%