Unaudited Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
NET INCOME (LOSS)	$ 11,370	$ (4,802)	$ 28,861	$ 10,261
OTHER COMPREHENSIVE INCOME:
Unrealized gain on derivative instruments, net of tax of $229 for the nine month period in 2011	0	0	0	402
Reclassifications to net income:
Hedging gain realized, net of tax of $5 and $16 for the three and nine month periods in 2012 and $6 and $76 for the three and nine month periods in 2011.	(9)	(10)	(27)	(133)
Post-retirement negative prior service cost, net of tax of $514 and $1,541 for the three and nine month periods in 2012 and $506 and $1,518 for the three and nine month periods in 2011.	(874)	(882)	(2,623)	(2,646)
Unrealized loss on derivative instruments, net of tax of $1,427 for the nine month period in 2011	0	0	0	2,505
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)	867	(393)	2,601	1,653
TOTAL COMPREHENSIVE INCOME (LOSS)	12,237	(5,195)	31,462	11,914
Pension actuarial loss, net of tax of $988 and $2,964 for the three and nine month periods in 2012 and $246 and $738 for the three and nine month periods in 2011 [Member]
Reclassifications to net income:
Actuarial loss, net of tax	1,682	429	5,047	1,287
Post-retirement actuarial loss, net of tax of $40 and $120 for the three and nine month periods in 2012 and $40 and $136 for the three and nine month periods in 2011 [Member]
Reclassifications to net income:
Actuarial loss, net of tax	$ 68	$ 70	$ 204	$ 238