Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 5,854	$ 5,471
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, par value	$ 0.0005	$ 0.0005
Preferred stock, shares issued
Common stock, shares authorized	50,000,000	50,000,000
Common stock, par value	$ 0.0005	$ 0.0005
Common stock, shares issued	28,201,541	27,696,593
Treasury stock, shares	16,652,022	16,566,701

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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