ASSOCIATE BENEFIT PLANS - Schedule of Net Periodic Benefit Cost Components of Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Postretirement Health Coverage
Business Acquisition [Line Items]
Service cost	$ 15	$ 14	$ 30	$ 29
Interest cost	18	19	35	38
Prior service cost amortization	(19)	(19)	(38)	(38)
Net gain recognition	(12)	(18)	(23)	(34)
Net periodic benefit cost	2	(4)	4	(5)
Pension Plan | Alliance
Business Acquisition [Line Items]
Service cost	10	10	20	20
Interest cost	74	75	147	150
Expected return on plan assets	(137)	(135)	(272)	(270)
Prior service cost amortization	0	0	0	0
Net gain recognition	0	0	0	0
Net periodic benefit cost	$ (53)	$ (50)	$ (105)	$ (100)