Quarterly Results of Operations (Results of Operations) (Details) (USD $) In Thousands, except Per Share data, 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
Quarterly Results of Operations [Abstract]
Net sales	$ 136,231	$ 142,820	$ 132,452	$ 125,979	$ 124,176	$ 129,134	$ 125,296	$ 120,155	$ 537,482	[1]	$ 498,761	[1]	$ 548,341	[1]
Gross margin	50,796	51,186	44,429	41,289	42,711	42,977	36,654	36,404	187,700		158,746		178,985
Income (loss) from continuing operations	$ 11,528	$ 13,572	$ 5,583	$ 6,976	$ 5,179	$ 59,124	$ 6,417	$ (1,586)	$ 37,659		$ 69,134		$ 44,250
Net income per basic share (in dollars per share)	$ 0.66	$ 0.79	$ 0.33	$ 0.41	$ 0.31	$ 3.60	$ 0.40	$ (0.10)	$ 2.19		$ 4.21		$ 2.76
Net income per diluted share (in dollars per share)	$ 0.64	$ 0.76	$ 0.32	$ 0.39	$ 0.30	$ 3.48	$ 0.39	$ (0.10)	$ 2.12		$ 4.07		$ 2.64

[1] Net sales are allocated to countries based on the location of the customer.