Consolidated Statements of Comprehensive Loss Parentheticals - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Consolidated Statements of Operations [Abstract]
Stock-based compensation expense associated with research and development expense	$ 1,184	$ 1,949	$ 2,470	$ 4,125
Stock-based compensation expense associated with selling, general and administrative expense	$ 1,602	$ 2,309	$ 3,167	$ 4,565