ASSOCIATE BENEFIT PLANS - Schedule of Net Periodic Benefit Cost Components of Postretirement Benefits (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Postretirement Health Coverage
Business Acquisition [Line Items]
Service cost		$ 15	$ 13
Interest cost		17	19
Prior service cost amortization		(19)	(19)
Net gain recognition		(9)	(15)
Net periodic cost (benefit)		4	(2)
Pension Plan | Alliance
Business Acquisition [Line Items]
Service cost		10	10
Interest cost		63	69
Expected return on plan assets		(117)	(147)
Prior service cost amortization		0	0
Net gain recognition		0	0
Net periodic cost (benefit)		(44)	$ (68)
Pension Plan | Beneficial
Business Acquisition [Line Items]
Service cost	$ 0	0
Interest cost	286	715
Expected return on plan assets	(481)	(1,594)
Prior service cost amortization	0	0
Net gain recognition	0	1
Net periodic cost (benefit)	(195)	(878)
Other Postretirement Benefits Plan | Beneficial
Business Acquisition [Line Items]
Service cost	8	28
Interest cost	59	138
Expected return on plan assets	0	0
Prior service cost amortization	0	0
Net gain recognition	0	(15)
Net periodic cost (benefit)	$ 67	$ 151