Selected Quarterly Financial Data (Unaudited) - Selected Quarterly Financial Data (Detail) (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	$ 40,025	$ 35,197	$ 32,175	$ 30,434	$ 32,116	$ 28,773	$ 28,223	$ 25,641	$ 136,123	$ 114,126	$ 89,676
Gross margin	25,554	22,096	19,742	18,451	19,168	16,803	16,503	15,241	85,843	67,715	44,529
Net income	$ 5,375	$ 5,114	$ 4,457	$ 3,298	$ 3,815	$ 3,677	$ 3,442	$ 3,804	$ 18,244	$ 14,738	$ (7,040)
Basic net income per share	$ 0.10	$ 0.10	$ 0.09	$ 0.06	$ 0.07	$ 0.07	$ 0.06	$ 0.07	$ 0.35	$ 0.27	$ (0.12)
Diluted net income per share	$ 0.10	$ 0.10	$ 0.08	$ 0.06	$ 0.07	$ 0.07	$ 0.06	$ 0.07	$ 0.34	$ 0.27	$ (0.12)