Other Financial Statement Data (Schedule of Accrued Expenses) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OTHER FINANCIAL STATEMENT DATA [Abstract]
Wages and benefits	$ 1,328	$ 2,673
Warranty liability	713	717	$ 584
Other	244	366
Accrued expenses	$ 2,285	$ 3,756