Summary of Significant Accounting Policies (Details 6) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Comprehensive income (loss)
Notional amount of interest rate swap contract	$ 50,000								$ 50,000
Components of accumulated other comprehensive loss
Interest rate swap, net of tax	(344)				(391)				(344)	(391)
Unrecognized pension and postretirement benefit plan liabilities, net of tax	(6,740)				(7,089)				(6,740)	(7,089)
Accumulated other comprehensive loss	(7,084)				(7,480)				(7,084)	(7,480)
Segment Reporting
Number of operating segments									1
Maximum percentage of net sales outside North America									2.00%
Product offerings
Net Sales	28,200	37,774	65,499	8,560	60,256	53,495	71,557	23,490	140,033	208,798	176,795
Equipment
Product offerings
Net Sales									123,308	177,806	151,808
Parts and accessories
Product offerings
Net Sales									$ 16,725	$ 30,992	$ 24,987