Summary of Significant Accounting Policies Concentration of Sales to Major Customers) (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Total revenue	$ 4,605	$ 1,190	$ 1,240	$ 1,851	$ 1,833	$ 11,572	$ 2,014	$ 2,188	$ 8,886	$ 17,607
Customer Revenue Concentration
Total revenue									$ 7,700	$ 10,000
Concentration Risk, Percentage									86.00%	57.00%
Second Commercial Customer
Total revenue									$ 1,200	$ 7,400
Concentration Risk, Percentage									13.00%	42.00%