ASSOCIATE BENEFIT PLANS - Schedule of Net Periodic Benefit Cost Components of Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Postretirement Health Coverage
Business Acquisition [Line Items]
Service cost	$ 17	$ 15
Interest cost	13	17
Prior service cost amortization	(19)	(19)
Net loss (gain) recognition	(5)	(9)
Net periodic cost (benefit)	6	4
Pension Plan | Alliance
Business Acquisition [Line Items]
Service cost		10
Interest cost		63
Expected return on plan assets		(117)
Net periodic cost (benefit)		(44)
Pension Plan | Beneficial
Business Acquisition [Line Items]
Service cost	0	0
Interest cost	530	715
Expected return on plan assets	(1,705)	(1,594)
Prior service cost amortization	0
Net loss (gain) recognition	6	1
Net periodic cost (benefit)	(1,169)	(878)
Other Postretirement Benefits Plan | Beneficial
Business Acquisition [Line Items]
Service cost	14	28
Interest cost	77	138
Expected return on plan assets	0	0
Prior service cost amortization	(3)
Net loss (gain) recognition	0	(15)
Net periodic cost (benefit)	$ 88	$ 151