Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 102,231	$ 95,907	$ 100,532	$ 95,618	$ 91,092	$ 90,477	$ 91,249	$ 86,631	$ 394,288	$ 359,449	$ 296,755
Gross profit	45,463	45,335	47,024	44,170	42,145	41,054	42,484	39,785	181,992	165,468	128,498
Income (loss) from operations	4,330	9,082	8,222	8,007	5,626	6,507	10,847	10,210	27,618	32,875	16,788
Income tax expense	1,209	1,811	2,719	2,169	806	2,120	3,746	3,159	7,908	9,831	4,328
Net income (loss)	$ 641	$ 7,226	$ 6,095	$ 5,748	$ 4,970	$ 4,563	$ 6,872	$ 6,639
Basic (in dollars per share)	$ 0.02	$ 0.17	$ 0.14	$ 0.14	$ 0.12	$ 0.11	$ 0.19	$ 0.19	$ 0.47	$ 0.59	$ 0.35
Diluted (in dollars per share)	$ 0.01	$ 0.17	$ 0.14	$ 0.14	$ 0.12	$ 0.11	$ 0.18	$ 0.18	$ 0.46	$ 0.58	$ 0.35