PENSION AND OTHER POSTRETIREMENT BENEFITS (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 plan	Dec. 31, 2013	Dec. 31, 2012 Point
PENSIONS AND OTHER POSTRETIREMENT BENEFITS
Number of plans	2
Number of plans covering nonunion employees	1
Requisite points for participation			70
Defined Benefit Plan, Benefit Obligation, Amount Settled	$ 30,200,000
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	(6,100,000)
Change in projected benefit obligation:
Liability loss related to curtailment	(6,509,000)	0	0
Change in plan assets:
Fair value of plan assets at the beginning of the period	244,302,000
Fair value of plan assets at the end of the period	225,862,000	244,302,000
Pension Benefits
Change in projected benefit obligation:
Projected benefit obligation at the beginning of period	261,714,000	278,416,000
Service cost	6,937,000	8,009,000	7,209,000
Interest cost	13,341,000	12,066,000	11,819,000
Participant contributions	0	0
Actuarial (gain) loss	58,922,000	(31,585,000)
Benefits paid	(36,476,000)	(5,192,000)
Liability loss related to curtailment	0	0
Liability gain related to settlement	(8,022,000)	0
Projected benefit obligation at the end of the period	296,416,000	261,714,000	278,416,000
Accumulated benefit obligation at end of the period	290,933,000	256,002,000
Change in plan assets:
Fair value of plan assets at the beginning of the period	244,302,000	193,389,000
Actual return on plan assets	18,036,000	35,460,000
Employer contributions	0	20,645,000
Participant contributions	0	0
Benefits paid	(6,270,000)	(5,192,000)
Benefits paid related to settlement	(30,206,000)	0
Fair value of plan assets at the end of the period	225,862,000	244,302,000	193,389,000
Funded status	(70,554,000)	(17,412,000)
Assumptions used in computing the benefit obligation
Discount rate			3.40%
Expected return on plan assets	7.10%	7.10%
Rate of compensation increase	2.50%	2.50%
Pension Benefits | Maximum
Assumptions used in computing the benefit obligation
Discount rate	5.18%	4.40%	5.15%
Pension Benefits | Minimum
Assumptions used in computing the benefit obligation
Discount rate	5.10%	4.30%	5.10%
Other Benefits
Change in projected benefit obligation:
Projected benefit obligation at the beginning of period	10,063,000	11,146,000
Service cost	23,000	37,000	50,000
Interest cost	385,000	325,000	457,000
Participant contributions	326,000	275,000
Actuarial (gain) loss	(362,000)	(583,000)
Benefits paid	(1,324,000)	(1,137,000)
Liability loss related to curtailment	(693,000)	0
Liability gain related to settlement	0	0
Projected benefit obligation at the end of the period	9,804,000	10,063,000	11,146,000
Accumulated benefit obligation at end of the period	0	0
Change in plan assets:
Fair value of plan assets at the beginning of the period	0	0
Actual return on plan assets	0	0
Employer contributions	998,000	862,000
Participant contributions	326,000	275,000
Benefits paid	(1,324,000)	(1,137,000)
Benefits paid related to settlement	0	0
Fair value of plan assets at the end of the period	0	0	0
Funded status	$ (9,804,000)	$ (10,063,000)
Assumptions used in computing the benefit obligation
Discount rate			5.00%
Other Benefits | Maximum
Assumptions used in computing the benefit obligation
Discount rate	5.05%	4.25%
Other Benefits | Minimum
Assumptions used in computing the benefit obligation
Discount rate	2.69%	2.25%