Restructuring (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended							1 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	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Employee Termination Costs	Dec. 31, 2010 Employee Termination Costs	Dec. 31, 2010 Other Exit Costs	Dec. 31, 2010 Facility closing Useful lives of manufacturing facility and certain equipment Adjustment	Aug. 31, 2010 Johnson City, TN item	Aug. 31, 2010 Rockland, ME item	Aug. 31, 2010 Milwaukee, WI item
Restructuring
Number of positions eliminated as a result of closure																100
Number of positions added as a result of the closure																	50	35
Reconciliation of changes in the restructuring reserves
Accrued restructuring reserves at the beginning of the period								$ 30		$ 30	$ 690	$ 30	$ 690
Charges to earnings											1,435		50	1,385
Payments										(30)	(2,095)	(30)	(710)	(1,385)
Accrued restructuring reserves at the end of the period											30		30
Additional disclosures
Accelerated depreciation											$ 2,071
Reduction in basic earnings per share (in dollars per share)	$ (0.05)	$ 0.11	$ 0.41	$ (0.19)	$ 0.28	$ 0.18	$ 0.44	$ (0.04)	$ 0.27	$ 0.87	$ 0.09				$ 0.07
Reduction in diluted earnings per share (in dollars per share)	$ (0.05)	$ 0.10	$ 0.40	$ (0.19)	$ 0.28	$ 0.18	$ 0.44	$ (0.04)	$ 0.26	$ 0.85	$ 0.09				$ 0.07