PENSION AND OTHER POSTRETIREMENT BENEFITS (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Benefits
Amounts recognized in the consolidated balance sheet consist of:
Current liabilities		$ (16,875,000)	$ (10,675,000)
Noncurrent liabilities		(56,336,000)	(34,130,000)
Net amount recognized		(73,211,000)	(44,805,000)
Amounts recognized in accumulated other comprehensive income before taxes:
Net actuarial loss		61,918,000	34,363,000
Prior service cost (benefit)		39,000	140,000
Net amount recognized		61,957,000	34,503,000
Total amount recognised in OCI
Net actuarial (gain)/loss		29,546,000	(5,262,000)
Amortization of:
Prior service cost/(credit)		(101,000)	(61,000)
Actuarial (gain)/loss		(1,996,000)	(1,058,000)
Total recognized in OCI		27,449,000	(6,381,000)
Amount included in accumulated other comprehensive income and expected to be recognized in net periodic pension cost in next fiscal year
Estimated net actuarial loss	4,109,000
Estimated prior service costs	14,000
Components of the net periodic benefit cost
Service cost		10,634,000	10,401,000	10,053,000
Interest cost		11,211,000	10,811,000	9,981,000
Expected return on plan assets		(13,008,000)	(11,671,000)	(10,644,000)
Amortization of prior service cost		32,000	61,000	74,000
Recognized actuarial loss		1,996,000	1,058,000	351,000
Curtailment (benefits) expense		69,000		27,000
Net periodic benefit cost		10,934,000	10,660,000	9,842,000
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)			6.10%	6.50%
Expected return on plan assets (as a percent)		8.20%	8.15%	8.25%
Rate of compensation increase (as a percent)		2.50%	4.00%	4.00%
Weighted-average asset allocations
Temporary Investment Funds (as a percent)		4.00%	2.00%
Equity Investment Funds (as a percent)		59.00%	64.00%
Fixed Income Funds (as a percent)		37.00%	34.00%
Total (as a percent)		100.00%	100.00%
Target allocation
Equity funds (as a percent)		60.00%
Fixed income funds (as a percent)		40.00%
Estimated future benefit payments
Expected contributions in next fiscal year	16,875,000
2012		5,111,000
2013		6,035,000
2014		7,025,000
2015		8,164,000
2016		9,313,000
2017-2021		67,557,000
Pension Benefits | Maximum
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)		5.75%
Pension Benefits | Minimum
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)		4.95%
Other Benefits
Amounts recognized in the consolidated balance sheet consist of:
Current liabilities		(1,229,000)	(1,494,000)
Noncurrent liabilities		(10,656,000)	(25,289,000)
Net amount recognized		(11,885,000)	(26,783,000)
Amounts recognized in accumulated other comprehensive income before taxes:
Net actuarial loss		4,539,000	8,360,000
Prior service cost (benefit)		(11,793,000)	(6,843,000)
Net amount recognized		(7,254,000)	1,517,000
Total amount recognised in OCI
Net actuarial (gain)/loss		(2,939,000)	1,450,000
Prior service cost/(credit)		(12,218,000)
Amortization of:
Prior service cost/(credit)		7,268,000	1,169,000
Actuarial (gain)/loss		(882,000)	(553,000)
Total recognized in OCI		8,771,000	2,066,000
Components of the net periodic benefit cost
Service cost		476,000	452,000	429,000
Interest cost		1,114,000	1,481,000	1,477,000
Amortization of prior service cost		(1,754,000)	(1,205,000)	(1,295,000)
Recognized actuarial loss		882,000	553,000	542,000
Curtailment (benefits) expense		(5,514,000)	(338,000)	(1,090,000)
Net periodic benefit cost		(4,796,000)	943,000	63,000
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)			6.10%	6.50%
Assumed health care cost trend rates
Annual rate of increase in the per capita cost of covered health care benefits (as a percent)	8.50%	8.00%
Ultimate rate to which the rate is assumed to decrease for 2019 and thereafter (as a percent)		5.00%
Annual rate of increase in the per capita cost of covered prescription drug benefits (as a percent)	8.50%	8.50%
Effects of 1% change in assumed health care cost trend rate
Effect of 1% increase on benefit obligation		347,000
Effect of 1% increase on aggregate of the service and interest cost components of net periodic benefit cost		32,000
Effect of 1% decrease on benefit obligation		343,000
Effect of 1% decrease on aggregate of the service and interest cost components of net periodic benefit cost		34,000
Estimated future benefit payments
Expected contributions in next fiscal year	1,229,000
2012		1,229,000
2013		1,245,000
2014		1,317,000
2015		1,316,000
2016		1,149,000
2017-2021		$ 4,077,000
Other Benefits | Maximum
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)		4.65%
Other Benefits | Minimum
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)		3.50%