Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (27,133)	$ (20,037)	$ (65,757)	$ (41,935)
Change in unrealized gain on available-for-sale debt securities	353	183	292	244
Comprehensive loss	$ (26,780)	$ (19,854)	$ (65,465)	$ (41,691)