15. Foreign Customer Sales (Details) - Foreign Sales [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Revenue, Major Customer [Line Items]
Total foreign sales	$ 14,620	$ 15,261
Sales Revenue [Member] | Canada, Mexico & South/Central America [Member]
Revenue, Major Customer [Line Items]
Total foreign sales	2,608	3,894
Sales Revenue [Member] | Pacific Rim [Member]
Revenue, Major Customer [Line Items]
Total foreign sales	2,417	2,906
Sales Revenue [Member] | Europe Africa And Middle East [Member]
Revenue, Major Customer [Line Items]
Total foreign sales	$ 9,595	$ 8,461