BENEFIT PLANS (Components of Net Periodic Benefit Cost- Pension Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31
Expected return on plan assets	7.00%	7.50%
Pension Benefits [Member]
Components of Net Periodic Benefit Cost
Service cost	$ 5,343	$ 4,851	$ 4,157
Interest cost	36,505	44,065	44,392
Expected return on plan assets	(51,562)	(54,736)	(50,802)
Settlement charge	0	2,031	0
Amortization of prior service cost (credit)	(43)	48	188
Amortization of actuarial (gain) loss	6,163	21,641	11,221
Net periodic benefit cost (credit)	(3,594)	17,900	9,156
Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income
Net actuarial loss (gain)	33,682	(3,615)	118,915
Reclassification of actuarial gain (loss)	(6,163)	(23,672)	(11,221)
Reclassification of prior service (cost) credit	43	(48)	(188)
Amount recognized in other comprehensive income	27,562	(27,335)	107,506
Amount recognized in net periodic pension benefit cost and other comprehensive income	$ 23,968	$ (9,435)	$ 116,662
Weighted-average assumptions used to determine net periodic benefit cost for years ended December 31
Discount rate — PBO	4.55%	4.14%	4.91%
Discount rate — service cost	4.68%	4.14%	4.91%
Discount rate — interest cost	3.79%	4.14%	4.91%
Expected return on plan assets	7.50%	7.50%	7.50%
Rate of compensation increase (for salary-related plans)	3.50%	3.70%	3.50%
Weighted-average assumptions used to determine benefit obligation at December 31
Discount rate	4.29%	4.54%	4.14%
Rate of compensation increase (for salary-related plans)	3.50%	3.50%	3.70%