EMPLOYEE BENEFIT PLANS - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 0
Interest cost	3,197	3,021	3,259
Expected return on plan assets	(3,107)	(3,934)	(3,781)
Amortization of losses (gains)	449	673	466
Net periodic benefit cost (credit)	539	(240)	(56)
Postretirement
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	7	6
Interest cost	54	38	53
Expected return on plan assets	0	0	0
Amortization of losses (gains)	0	2	(1)
Net periodic benefit cost (credit)	$ 60	$ 47	$ 58