ASSOCIATE BENEFIT PLANS - Schedule of Net Periodic Benefit Cost Components of Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Postretirement Health Coverage
Business Acquisition [Line Items]
Service cost	$ 15	$ 11	$ 45	$ 40
Interest cost	18	16	53	54
Prior service cost amortization	(19)	(19)	(57)	(57)
Net gain recognition	(11)	(18)	(34)	(52)
Net periodic benefit cost	3	(10)	7	(15)
Pension Plan | Alliance
Business Acquisition [Line Items]
Service cost	10	10	30	30
Interest cost	75	75	222	225
Expected return on plan assets	(138)	(135)	(410)	(405)
Prior service cost amortization	0	0	0	0
Net gain recognition	0	0	0	0
Net periodic benefit cost	$ (53)	$ (50)	$ (158)	$ (150)