Restructuring (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013 Item	Dec. 31, 2012 Item
Restructuring reserve activity
Restructuring charges (income)	(24,000)
Payments	2,616,000
Charge for the write-off of goodwill	419,000
Activated Carbon and Service
Restructuring Charges
Restructuring charges excluding gain on sale	600,000
Restructuring reserve activity
Accrual at beginning of period	3,226,000
Restructuring charges (income)	(24,000)
Payments	(2,616,000)
Non-cash charges	578,000
Accrual at end of period	1,164,000
Charge for the write-off of goodwill	419,000
Activated Carbon and Service | Facility closing
Restructuring reserve activity
Restructuring charges (income)	578,000
Non-cash charges	578,000
Release of foreign currency translation adjustments	1,032,000
Charge for the write-off of goodwill	419,000
Activated Carbon and Service | Employee Termination Benefits
Restructuring reserve activity
Accrual at beginning of period	3,226,000
Restructuring charges (income)	462,000
Payments	(2,524,000)
Accrual at end of period	1,164,000
Activated Carbon and Service | Gain on Sale
Restructuring reserve activity
Restructuring charges (income)	(578,000)
Non-cash charges	578,000
Activated Carbon and Service | Other Costs
Restructuring reserve activity
Restructuring charges (income)	92,000
Payments	(92,000)
Activated Carbon and Service | Employees
Restructuring reserve activity
Number of employees remaining to be paid	16	67
Number of positions reduced	3
Number of employees to whom amount paid	(54)
Number of employees remaining to be paid	16	67