BENEFIT PLANS (Components of Net Periodic Benefit Cost- PostRetirement Plans) (Details) - Postretirement Plans [Member] - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of Net Periodic Benefit Cost
Service cost		$ 1,123	$ 1,894	$ 2,146
Interest cost		1,209	2,485	3,297
Curtailment gain	$ (3,832)	0	0	(3,832)
Amortization of prior service cost (credit)		(4,236)	(4,232)	(4,327)
Amortization of actuarial (gain) loss		(1,751)	37	227
Net periodic benefit cost (credit)		(3,655)	184	(2,489)
Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income
Net actuarial loss (gain)		(111)	(35,209)	(5,256)
Reclassification of actuarial gain (loss)		1,751	(37)	(227)
Reclassification of prior service (cost) credit		4,236	4,232	8,159
Amount recognized in other comprehensive income		5,876	(31,014)	2,676
Amount recognized in net periodic pension benefit cost and other comprehensive income		$ 2,221	$ (30,830)	$ 187
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Healthcare cost trend rate assumed for next year				7.50%
Rate to which the cost trend rate gradually declines				5.00%
Year that the rate reaches the rate it is assumed to maintain				2025
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31
Discount rate — PBO		3.69%	3.50%	4.10%
Discount rate — service cost		3.77%	3.50%	4.10%
Discount rate — interest cost		2.81%	3.50%	4.10%
Weighted-average assumptions used to determine benefit obligation at December 31
Discount rate		3.58%	3.69%	3.50%