EMPLOYEE BENEFIT PLANS (Settlement) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended									6 Months Ended	10 Months Ended	12 Months Ended
	Jan. 31, 2014	Dec. 31, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Oct. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 01, 2015
Distributions and pension settlement expense
Pension settlement expense, pre-tax														$ 3,202	$ 6,595	$ 2,111
Nonunion Defined Benefit Pension Plan
Distributions and pension settlement expense
Pension settlement distributions														20,622	57,518	20,104
Pension settlement expense, pre-tax														$ 3,202	$ 5,880	$ 2,111
Pension settlement expense per diluted share, net of taxes														$ 0.07	$ 0.14	$ 0.05
Lump-sum distributions															$ 32,100
Premium paid to purchase nonparticipating annuity contract	$ 25,400														25,400
Pre-tax amounts included in accumulated other comprehensive loss that have not yet been recognized in net periodic benefit cost
Unrecognized net actuarial loss		$ 24,303	$ 28,457				$ 24,303							$ 28,457	24,303
Total		$ 24,303	$ 28,457				$ 24,303							28,457	$ 24,303
Pre-tax amounts, which are reported within accumulated other comprehensive loss, expected to be recognized as components of net periodic benefit cost in next fiscal year
Unrecognized net actuarial loss														3,575
Total														$ 3,575
Weighted-average assumptions used to determine nonunion benefit obligations
Discount rate (as a percent)		3.20%	3.50%				3.20%							3.50%	3.20%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)			3.40%	3.50%	3.00%	3.20%	3.40%	3.30%	3.50%	3.70%	3.90%	3.10%			3.80%
Expected return on plan assets (as a percent)														6.50%	6.50%	7.50%
Rate of compensation increase (as a percent)																3.30%
Estimated future benefit payments
2016			$ 27,392											$ 27,392
2017			13,560											13,560
2018			12,821											12,821
2019			12,590											12,590
2020			12,815											12,815
2021-2025			54,168											54,168
Required minimum contributions
Adjusted funding target attainment percentage																	107.30%
Supplemental Benefit Plan
Distributions and pension settlement expense
Pension settlement distributions														$ 1,941	$ 853
Pension settlement expense, pre-tax															$ 715
Pension settlement expense per diluted share, net of taxes															$ 0.02
Period of delay for pension settlement distribution to key employees														6 months
Pre-tax amounts included in accumulated other comprehensive loss that have not yet been recognized in net periodic benefit cost
Unrecognized net actuarial loss		$ 1,207	1,001				$ 1,207							$ 1,001	$ 1,207
Total		$ 1,207	$ 1,001				$ 1,207							1,001	$ 1,207
Pre-tax amounts, which are reported within accumulated other comprehensive loss, expected to be recognized as components of net periodic benefit cost in next fiscal year
Unrecognized net actuarial loss														152
Total														$ 152
Weighted-average assumptions used to determine nonunion benefit obligations
Discount rate (as a percent)		2.50%	2.60%				2.50%							2.60%	2.50%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)		2.50%											2.80%	2.50%		2.10%
Estimated future benefit payments
2016			$ 246											$ 246
2017			989											989
2019			3,107											3,107
Postretirement Health Benefit Plan
Pre-tax amounts included in accumulated other comprehensive loss that have not yet been recognized in net periodic benefit cost
Unrecognized net actuarial loss		$ 5,327	6,280				$ 5,327							6,280	$ 5,327
Unrecognized prior service credit		(697)	(507)				(697)							(507)	(697)
Total		$ 4,630	$ 5,773				$ 4,630							5,773	$ 4,630
Pre-tax amounts, which are reported within accumulated other comprehensive loss, expected to be recognized as components of net periodic benefit cost in next fiscal year
Unrecognized net actuarial loss														734
Unrecognized prior service credit														(190)
Total														$ 544
Weighted-average assumptions used to determine nonunion benefit obligations
Discount rate (as a percent)		3.90%	4.20%				3.90%							4.20%	3.90%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)														3.90%	4.70%	3.80%
Effects of one-percentage-point change in assumed health care cost trend rates
Effect of one-percentage-point increase on total of service and interest cost components														$ 272
Effect of one-percentage-point decrease on total of service and interest cost components														(213)
Effect of one-percentage-point increase on postretirement benefit obligation														4,815
Effect of one-percentage-point decrease on postretirement benefit obligation														(3,846)
Estimated future benefit payments
2016			$ 736											736
2017			805											805
2018			889											889
2019			956											956
2020			1,035											1,035
2021-2025			$ 6,202											$ 6,202
Postretirement Health Benefit Plan | Pre-65
Assumed health care cost trend rates
Health care cost trend rate assumed for next year (as a percent)														6.70%	7.50%
Rate to which the cost trend rate is assumed to decline (as a percent)														4.50%	4.50%
Year that the rate reaches the cost trend assumed rate		2027	2030				2027							2030	2027
Postretirement Health Benefit Plan | Post-65
Assumed health care cost trend rates
Health care cost trend rate assumed for next year (as a percent)															5.80%
Rate to which the cost trend rate is assumed to decline (as a percent)															4.50%
Year that the rate reaches the cost trend assumed rate		2020					2020								2020