Restructuring (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended						12 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013 Activated Carbon and Service	Jun. 30, 2013 Activated Carbon and Service	Jun. 30, 2013 Activated Carbon and Service Facility closing	Jun. 30, 2013 Activated Carbon and Service Employee Termination Benefits	Jun. 30, 2013 Activated Carbon and Service Gain on Sale	Jun. 30, 2013 Activated Carbon and Service Other Costs	Jun. 30, 2013 Activated Carbon and Service Employees Item	Dec. 31, 2012 Activated Carbon and Service Employees Item
Restructuring Charges
Restructuring (income) charges excluding gain on sale			$ (18)	$ 500
Restructuring reserve activity
Accrual at beginning of period				3,226		3,226
Restructuring charges (income)	(18)	(42)		(42)		444	(578)	92
Payments				(3,091)		(2,999)		(92)
Non-cash charges				578			578
Accrual at end of period			671	671		671
Number of employees remaining to be paid									10	67
Number of positions reduced									4
Number of employees to whom amount paid									(61)
Number of employees remaining to be paid									10	67
Release of foreign currency translation adjustments					1,032
Charge for the write-off of goodwill					$ 419