Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 190,897	$ 179,337	$ 186,549	$ 171,069	$ 157,715	$ 156,975	$ 151,071	$ 138,077	$ 727,852	$ 603,838	$ 542,149
Gross profit	85,656	80,514	84,141	75,942	70,256	67,815	66,854	60,100	326,253	265,025	235,781
Income from operations	13,219	879	13,362	5,609	12,602	2,987	11,581	7,706	33,069	34,876	37,543
Income tax expense	4,474	1,364	1,830	690	2,116	(978)	2,572	1,555	8,358	5,265	7,398
Net income	$ 6,806	$ (3,569)	$ 9,483	$ 14,803	$ 7,507	$ 973	$ 7,290	$ 4,351	$ 27,523	$ 20,121	$ 23,802
Basic (in dollars per share)	$ 0.14	$ (0.07)	$ 0.19	$ 0.33	$ 0.17	$ 0.02	$ 0.16	$ 0.10	$ 0.56	$ 0.45	$ 0.54
Diluted (in dollars per share)	$ 0.13	$ (0.07)	$ 0.19	$ 0.32	$ 0.17	$ 0.02	$ 0.16	$ 0.10	$ 0.55	$ 0.45	$ 0.53