Consolidated Statements of Loss and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (67,484)	$ (37,940)
Other comprehensive income (loss);
Unrealized gain on fair value of investments	16	26
Unrealized gain (loss) on currency translation	4	(16)
Comprehensive loss	$ (67,464)	$ (37,930)