Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Information
Net Sales	$ 133,092	$ 139,375	$ 140,432	$ 135,040	$ 141,777	$ 135,467	$ 148,403	$ 136,608	$ 547,939	$ 562,255	$ 541,472
Carbon products
Segment Information
Net Sales									460,681	465,885	466,046
Capital equipment
Segment Information
Net Sales									49,036	61,588	40,650
Equipment leasing
Segment Information
Net Sales									15,127	13,886	14,815
Carbon cloth products
Segment Information
Net Sales									10,721	10,422	7,868
Spare parts
Segment Information
Net Sales									5,899	4,462	5,624
Home consumer products
Segment Information
Net Sales									5	28	862
Other services
Segment Information
Net Sales									$ 6,470	$ 5,984	$ 5,607