Summary of Significant Accounting Policies Concentration of Sales to Major Customers) (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Total revenue	$ 1,833	$ 11,572	$ 2,014	$ 2,188	$ 2,302	$ 5,425	$ 1,339	$ 568	$ 17,607	$ 9,634
Customer Revenue Concentration
Total revenue									$ 10,000	$ 5,800
Concentration Risk, Percentage									57.00%	60.00%
Second Commercial Customer
Total revenue									$ 7,400	$ 2,300
Concentration Risk, Percentage									42.00%	24.00%