Quarterly Results (Unaudited) (Details) - 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
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net sales	$ 91,668	$ 104,568	$ 102,319	$ 85,422	$ 97,229	$ 94,360	$ 90,275	$ 76,768	$ 383,977	$ 358,632	$ 356,322
Gross profit	26,510	33,092	32,747	25,731	29,581	30,185	27,117	21,798	118,080	108,681	108,263
Net income	$ 11,420	$ 15,682	$ 14,341	$ 10,806	$ 12,948	$ 13,251	$ 11,130	$ 8,399	$ 53,376	$ 45,728	$ 44,158
Earnings per share:
Basic (usd per share)	$ 0.22	$ 0.30	$ 0.27	$ 0.20	$ 0.24	$ 0.24	$ 0.21	$ 0.16	$ 1.01	$ 0.85	$ 0.81
Diluted (usd per share)	$ 0.21	$ 0.29	$ 0.27	$ 0.20	$ 0.24	$ 0.24	$ 0.20	$ 0.15	$ 1.00	$ 0.84	$ 0.80
Accounting Standards Update 2016-09, Statutory Tax Withholding Component [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income			$ 400	$ 800
Earnings per share:
Basic (usd per share)			$ 0.01	$ 0.01
Diluted (usd per share)			$ 0.01	$ 0.01