Concentration of Sales to Major Customers (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Customer Revenue Concentration
Total revenue	$ 2,700	$ 3,900	$ 3,700	$ 10,800
Concentration Risk, Percentage	44.00%	88.00%	44.00%	91.00%
Second Commercial Customer
Total revenue	$ 2,300		$ 2,300
Concentration Risk, Percentage	38.00%		28.00%
Third Commercial Customer
Total revenue	$ 359		$ 1,200
Concentration Risk, Percentage	6.00%		15.00%
Accounts Receivable Concentration
Accounts receivable	$ 182		$ 182
Concentration Risk, Percentage			76.00%
Second Receivable
Accounts receivable	$ 36		$ 36
Concentration Risk, Percentage			15.00%