Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Basis of Presentation [Abstract]
Warrants exercised for common stock	$ 104	$ 3,538
Interest paid (net of interest capitalized)	6	1,161
Additions to equipment in process included in accounts payable	46	191
Right-of-use asset and lease liability recognized	$ 2,338	$ 0