Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid- in- Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Balances at Dec. 31, 2017	$ (7,615)	$ 1	$ 21,773		$ (29,389)
Balance (in shares) at Dec. 31, 2017		7,888
Common stock issued	78,806		78,806
Common stock issued (in shares)		4,801
Initial public offering costs	(3,556)		(3,556)
Settlement of stock-based compensation liability	18,243		18,243
Forfeitures of liability-classified awards	1,313		1,313
Stock-based compensation	10,346		10,346
Net loss	(30,832)				(30,832)
Balances at Dec. 31, 2018	66,705	$ 1	126,925		(60,221)
Balance (in shares) at Dec. 31, 2018		12,689
Adoption of accounting standard (See Note 2) at Jan. 1, 2019	21				21
Balances at Jan 1, 2019	66,726				(60,200)
Common stock issued	(188)		(188)
Common stock issued (in shares)		1,081
Stock-based compensation	23,543		23,543
Other comprehensive income	26			$ 26
Net loss	(56,957)				(56,957)
Balances at Dec. 31, 2019	$ 33,150	$ 1	$ 150,280	$ 26	$ (117,157)
Balance (in shares) at Dec. 31, 2019		13,770