Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Loss	$ (83,948)	$ (32,811)	$ (31,154)
Other comprehensive income (loss):
Unrealized gain (loss) on available-for-sale securities	535	(288)	(56)
Comprehensive loss	$ (83,413)	$ (33,099)	$ (31,210)