Concentration of Sales to Major Customers) (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Total revenue	$ 1,190	$ 11,572	$ 4,281	$ 15,774
Customer Revenue Concentration
Total revenue	$ 823	$ 10,000	$ 3,700	$ 10,000
Concentration Risk, Percentage	69.00%	86.00%	86.00%	63.00%
Second Commercial Customer
Total revenue	$ 360	$ 1,500	$ 559	$ 5,600
Concentration Risk, Percentage	30.00%	13.00%	13.00%	35.00%
Accounts Receivable Concentration
Accounts receivable	$ 505		$ 505
Concentration Risk, Percentage			100.00%