Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information (unaudited)
Net sales	$ 33,933	$ 34,441	$ 36,499	$ 33,977	$ 35,267	$ 35,406	$ 34,025	$ 34,609	$ 138,850	$ 139,307	$ 139,223
Gross profit	9,013	9,510	10,293	8,638	8,406	9,752	9,545	9,177	$ 37,454	$ 36,880	$ 41,014
Net income	$ 1,676	$ 1,992	$ 2,272	$ 1,653	$ 1,571	$ 2,066	$ 1,860	$ 2,062
Basic net income per share (in dollars per share)	$ 0.24	$ 0.28	$ 0.32	$ 0.23	$ 0.22	$ 0.29	$ 0.27	$ 0.30	$ 1.07	$ 1.08	$ 1.65
Diluted net income per share (in dollars per share)	$ 0.23	$ 0.28	$ 0.32	$ 0.23	$ 0.22	$ 0.29	$ 0.26	$ 0.29	$ 1.05	$ 1.05	$ 1.59

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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