Quarterly Results of Operations (Unaudited) (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 Financial Information Disclosure [Abstract]
Net sales	$ 120,016	$ 115,210	$ 109,875	$ 103,948	$ 102,231	$ 95,907	$ 100,532	$ 95,618	$ 449,049	$ 394,288	$ 359,449
Gross profit	53,359	51,030	46,985	42,993	45,463	45,335	47,024	44,170	194,367	181,992	165,468
Income from operations	10,916	8,391	6,780	1,757	4,330	9,082	8,222	8,007	19,839	27,618	32,875
Income tax expense	1,642	833	1,253	(459)	1,209	1,811	2,719	2,169	3,269	7,908	9,831
Net income	$ 6,540	$ 5,607	$ 3,752	$ 671	$ 641	$ 7,226	$ 6,095	$ 5,748
Basic (in dollars per share)	$ 0.15	$ 0.13	$ 0.09	$ 0.02	$ 0.02	$ 0.17	$ 0.14	$ 0.14	$ 0.39	$ 0.47	$ 0.59
Diluted (in dollars per share)	$ 0.15	$ 0.13	$ 0.09	$ 0.02	$ 0.01	$ 0.17	$ 0.14	$ 0.14	$ 0.39	$ 0.46	$ 0.58