Warrants (Fair Value of Warrants) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Class of Warrant or Right [Line Items]
Fair Value	$ 1,524		$ 1,524		$ 23
Change in Fair Value of common stock warrant liability	(1,481)	$ 536	(1,501)	$ 1,330
2018 January and February Issuance [Member]
Class of Warrant or Right [Line Items]
Fair Value	1,216		1,216		22
2017 May issuance [Member]
Class of Warrant or Right [Line Items]
Fair Value	$ 308		$ 308		$ 1