Restructuring (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012 Restructuring charges	Sep. 30, 2012 Restructuring charges	Sep. 30, 2013 Foreign Currency Translation Adjustments Amount Reclassified from Accumulated Other Comprehensive Loss	Sep. 30, 2012 Belgium warehouse Restructuring charges	Sep. 30, 2012 Belgium warehouse Restructuring charges	Mar. 31, 2013 Datong, China activated carbon manufacturing facility Restructuring charges	Sep. 30, 2012 Datong, China activated carbon manufacturing facility Restructuring charges	Sep. 30, 2012 Datong, China activated carbon manufacturing facility Restructuring charges	Sep. 30, 2013 Employee Termination Benefits	Sep. 30, 2013 Gain on Sale	Mar. 31, 2013 Gain on Sale Datong, China activated carbon manufacturing facility Restructuring charges	Mar. 31, 2013 Gain on Sale Datong, China activated carbon manufacturing facility Foreign Currency Translation Adjustments Amount Reclassified from Accumulated Other Comprehensive Loss	Sep. 30, 2013 Other Costs	Sep. 30, 2013 Employees Item
Restructuring Charges
Restructuring (income) charges during period	$ (87,000)		$ 400,000
Pretax gain on sale										600,000
Charge for the write-off of goodwill															400,000
Impairment charges								400,000	400,000		3,600,000	3,600,000
Termination benefits					3,800,000	3,800,000
Restructuring reserve activity
Accrual at beginning of period			3,226,000										3,226,000
Restructuring charges (income)	(87,000)	7,958,000	(129,000)	7,958,000			(1,032,000)						357,000	(578,000)		(1,000,000)	92,000
Payments			(3,124,000)										(3,032,000)				(92,000)
Non-cash charges			578,000											578,000
Accrual at end of period	$ 551,000		$ 551,000										$ 551,000
Number of employees remaining to be paid																		67
Number of positions reduced																		4
Number of employees to whom amount paid																		(67)
Number of employees remaining to be paid																		4