PENSION PLANS AND OTHER POST-RETIREMENT BENEFITS - Other Non-qualified Deferred Comp Agreements (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) item	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Other Non-qualified Deferred Compensation Agreements
Minimum number of years benefits are payable			5 years
Minimum age at which payments under deferred compensation agreements may begin			55 years
Payment related to deferred compensation agreements	$ 0	$ 0	$ 300,000	$ 200,000
Net present value of the remaining obligations	1,400,000		$ 1,400,000		$ 1,600,000
Number of life insurance policies | item			25
Excess of cash surrender value of remaining life insurance policies over notes payable	2,500,000		$ 2,500,000		$ 2,400,000
Proceeds from life insurance policies	0	$ 0	0	$ 0
New benefits accrued	$ 0		$ 0