Stockholders' Equity - Schedule of Allocation of Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock-based compensation expense	$ 901	$ 361	$ 2,899	$ 853
Cost of product sales
Stock-based compensation expense	32	35	124	132
Research and development cost
Stock-based compensation expense	34	26	168	215
General and administrative expense
Stock-based compensation expense	$ 835	$ 300	$ 2,607	$ 506