BENEFIT PLANS (Components of Net Periodic Benefit Cost- Pension Benefits) (Details) - USD ($) $ in Thousands	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2020	Nov. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31
Expected return on plan assets	5.25%	5.75%		5.75%
Pension Plans, Defined Benefit [Member]
Components of Net Periodic Benefit Cost
Service cost			$ 4,899	$ 4,995	$ 5,716
Interest cost			29,335	37,640	35,503
Expected return on plan assets			(48,599)	(47,751)	(59,188)
Settlement charge			22,740	0	0
Amortization of prior service cost			1,340	1,340	1,340
Amortization of actuarial loss			11,845	5,433	9,826
Net periodic benefit cost (credit)			21,560	1,657	(6,803)
Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income
Net actuarial loss (gain)			(3,446)	33,717	(555)
Prior service cost			0	0	0
Reclassification of prior service (cost) credit			(1,340)	(1,340)	(1,340)
Reclassification of actuarial loss			(34,585)	(5,433)	(9,826)
Amount recognized in other comprehensive income			(39,371)	26,944	(11,721)
Amount recognized in net periodic pension benefit cost and other comprehensive income			$ (17,811)	$ 28,601	$ (18,524)
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31
Discount rate — PBO			3.22%	4.39%	3.72%
Discount rate — service cost	2.89%	3.49%		4.59%	3.90%
Discount rate — interest cost			2.78%	4.02%	3.35%
Expected return on plan assets	5.25%	5.75%		5.75%	7.00%
Weighted-average assumptions used to determine benefit obligation at December 31
Discount rate	2.57%		2.57%	3.28%	4.39%