Segment Information (Details 3) (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
United States
Segment Information
Net Sales									272,644	261,167	254,953
Japan
Segment Information
Net Sales									60,804	71,141	73,335
United Kingdom
Segment Information
Net Sales									40,215	37,991	32,948
France
Segment Information
Net Sales									27,969	21,456	20,302
Germany
Segment Information
Net Sales									18,784	20,120	20,513
Canada
Segment Information
Net Sales									16,945	17,861	19,986
China
Segment Information
Net Sales									15,832	15,179	10,369
Belgium
Segment Information
Net Sales									10,690	10,112	11,419
Singapore
Segment Information
Net Sales									9,364	10,380	6,661
South Korea
Segment Information
Net Sales									7,364	20,178	12,546
Switzerland
Segment Information
Net Sales									5,334	4,683	3,324
Netherlands
Segment Information
Net Sales									5,283	6,009	6,861
Spain
Segment Information
Net Sales									3,806	4,049	3,665
Australia
Segment Information
Net Sales									3,775	3,214	6,424
Denmark
Segment Information
Net Sales									3,639	4,142	4,178
Other
Segment Information
Net Sales									$ 45,491	$ 54,573	$ 53,988