Quarterly Results of Operations (Unaudited) - Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 26,300	$ 28,400	$ 27,100	$ 27,100	$ 25,700	$ 26,500	$ 28,900	$ 27,900	$ 108,920	$ 108,994	$ 103,846
Gross profit	9,100	9,400	8,500	8,200	7,500	8,100	9,200	8,600	35,167	33,401	32,248
Operating income	4,000	4,500	3,700	3,400	2,600	3,400	4,300	3,700	15,574	13,971	13,607
Net income	$ 2,900	$ 3,000	$ 2,400	$ 2,200	$ 1,700	$ 2,200	$ 2,800	$ 2,400	$ 10,457	$ 9,118	$ 8,661
Basic and diluted earnings per share	$ 0.23	$ 0.24	$ 0.20	$ 0.18	$ 0.13	$ 0.18	$ 0.23	$ 0.19	$ 0.84	$ 0.73	$ 0.70