Comprehensive (Loss) Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Other Comprehensive Income (Loss), before Tax [Abstract]
Foreign currency translation adjustment	$ (54)	$ (79)	$ 81	$ (80)
Reclassification of net gains on derivative instruments to net income	(297)	(297)	(891)	(891)
Pension and postretirement medical liability adjustment	0	0	0	333
Other comprehensive loss	(351)	(376)	(810)	(638)
Other Comprehensive Income (Loss), Tax [Abstract]
Foreign currency translation adjustment	0	0	0	0
Reclassification of net gains on derivative instruments to net income	114	119	342	339
Pension and postretirement medical liability adjustment	0	0	0	(128)
Other comprehensive loss	114	119	342	211
Other comprehensive (loss) income, net of tax:
Foreign currency translation	(54)	(79)	81	(80)
Reclassification of net gains on derivative instruments to net income	(183)	(178)	(549)	(552)
Pension and postretirement medical liability adjustment	0	0	0	205
Total Other Comprehensive Loss	(237)	(257)	(468)	(427)
Accumulated Other Comprehensive Income [Abstract]
Foreign currency translation	447		447		366
Derivative instruments designated as cash flow hedges	3,694		3,694		4,243
Pension and postretirement medical plans	(2,292)		(2,292)		(2,292)
Accumulated other comprehensive income	$ 1,849		$ 1,849		$ 2,317