Consolidated Statements of Comprehensive Loss Parentheticals - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Consolidated Statements of Operations [Abstract]
Stock-based compensation expense associated with research and development expense	$ 1,949	$ 1,903	$ 4,125	$ 3,671
Stock-based compensation expense associated with selling, general and administrative expense	$ 2,309	$ 1,863	$ 4,565	$ 3,506