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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Postretirement Health Coverage
Business Acquisition [Line Items]
Service cost	$ 15	$ 13	$ 45	$ 40
Interest cost	17	20	51	58
Prior service cost amortization	(19)	(19)	(57)	(57)
Net loss (gain) recognition	(9)	(16)	(27)	(47)
Net periodic cost (benefit)	4	(2)	12	(6)
Pension Plan | Alliance
Business Acquisition [Line Items]
Service cost	0	10	17	30
Interest cost	0	70	105	208
Expected return on plan assets	0	(150)	(196)	(445)
Prior service cost amortization	0	0	0	0
Net loss (gain) recognition	0	0	0	0
Plan settlement loss	0	0	1,431	0
Net periodic cost (benefit)	0	(70)	1,357	(207)
Pension Plan | Beneficial
Business Acquisition [Line Items]
Service cost	0	0	0	0
Interest cost	728	857	2,183	1,999
Expected return on plan assets	(1,590)	(1,442)	(4,773)	(3,365)
Prior service cost amortization	0	0	0	0
Net loss (gain) recognition	1	0	3	0
Net periodic cost (benefit)	(861)	(585)	(2,587)	(1,366)
Other Postretirement Benefits Plan | Beneficial
Business Acquisition [Line Items]
Service cost	2	23	59	53
Interest cost	108	177	381	413
Expected return on plan assets	0	0	0	0
Prior service cost amortization	(76)	0	(76)	0
Net loss (gain) recognition	(6)	0	(15)	0
Net periodic cost (benefit)	$ 28	$ 200	$ 349	$ 466