INCOME TAXES (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
INCOME TAXES
State tax, low end of range of rate (as a percent)			6.00%
State tax, high end of range of rate (as a percent)			6.50%
Net decrease in valuation allowance		$ 8,000,000	$ 300,000	$ 3,300,000
Alternative fuel tax credit, prior year			900,000
Alternative fuel tax credit, current year			500,000
Reduction in net deferred tax assets due to nonunion defined benefit pension plan curtailment	18,000,000
Reduction in pension liability due to nonunion defined benefit pension plan curtailment	46,300,000
Refund of federal and state taxes			2,200,000
State and foreign income taxes paid			900,000
Reconciliation between the effective income tax rate, as computed on income (loss) before income taxes, and the statutory federal income tax rate
Income tax expense (benefit) at the statutory federal rate	2,753,000	2,129,000	(5,403,000)	(5,758,000)
Federal income tax effects of:
Net reversal in valuation allowances	(528,000)	(7,973,000)	(216,000)	(3,333,000)
Alternative fuel tax credit	(241,000)		(1,421,000)
Effect of permanent differences and other	703,000	(635,000)	721,000	(871,000)
State income taxes	300,000	722,000	(602,000)	(169,000)
Total income tax expense (benefit)	$ 2,987,000	$ (5,757,000)	$ (6,921,000)	$ (10,131,000)
Income tax expense (benefit) at the statutory federal rate (as a percent)	35.00%	35.00%	(35.00%)	(35.00%)
Federal income tax effects of:
Net reversal in valuation allowances (as a percent)	(6.70%)	(131.00%)	(1.40%)	(20.30%)
Alternative fuel tax credit (as a percent)	(3.00%)		(9.20%)
Effect of permanent differences and other (as a percent)	8.90%	(10.40%)	4.70%	(5.30%)
State income taxes (as a percent)	3.80%	11.80%	(3.90%)	(1.00%)
Total income tax expense (benefit) (as a percent)	38.00%	(94.60%)	(44.80%)	(61.60%)