Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 132,780	$ 128,808	$ 128,865	$ 119,236	$ 120,016	$ 115,210	$ 109,875	$ 103,948	$ 509,689	$ 449,049	$ 394,288
Gross profit	60,134	57,421	55,624	52,043	53,359	51,030	46,985	42,993	225,222	194,367	181,992
Income from operations	14,217	12,076	7,384	6,489	10,916	8,391	6,780	1,757	31,572	19,839	27,618
Income tax expense	3,680	2,489	1,366	1,063	1,642	833	1,253	(459)	8,598	3,269	7,908
Net income	$ 8,671	$ 7,764	$ 3,716	$ 2,823	$ 6,540	$ 5,607	$ 3,752	$ 671
Basic (in dollars per share)	$ 0.20	$ 0.18	$ 0.09	$ 0.07	$ 0.15	$ 0.13	$ 0.09	$ 0.02	$ 0.53	$ 0.39	$ 0.47
Diluted (in dollars per share)	$ 0.20	$ 0.18	$ 0.09	$ 0.07	$ 0.15	$ 0.13	$ 0.09	$ 0.02	$ 0.53	$ 0.39	$ 0.46