CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at beginning at Dec. 31, 2017	$ 4	$ 4,001	$ (2)	$ (57,525)	$ (53,522)
Balance at beginning (in shares) at Dec. 31, 2017	3,970,586
Increase (decrease) in Stockholders' Equity
Unrealized gain (loss) on marketable securities			(6)		(6)
Reclassification of warrant to stockholders' equity		93			93
Conversion of convertible preferred stock into common stock	$ 15	109,217			109,232
Conversion of convertible preferred stock into common stock (in shares)	15,109,950
Sale of common shares sold in IPO, net of offering costs	$ 6	77,833			77,839
Sale of common shares sold in IPO, net of offering costs (in shares)	6,164,000
Sale of common shares, net of issuance costs	$ 1	17,095			17,096
Sale of common shares (in shares)	980,392
Restricted shares forfeited during the period (in shares)	(8,125)
Exercise of stock options		6			6
Exercise of stock options (in shares)	898
Equity-based compensation expense		5,211			5,211
Cumulative effective adjustment for ASU 2018-07		(3)		3
Net Loss				(49,326)	(49,326)
Balance at end at Dec. 31, 2018	$ 26	213,453	(8)	(106,848)	106,623
Balance at end (in shares) at Dec. 31, 2018	26,217,701
Increase (decrease) in Stockholders' Equity
Unrealized gain (loss) on marketable securities			45		45
Sale of common shares, net of issuance costs	$ 4	48,344			48,348
Sale of common shares (in shares)	3,450,000
Restricted shares forfeited during the period (in shares)	(4,210)
Exercise of stock options		913			913
Exercise of stock options (in shares)	129,431
Equity-based compensation expense		7,972			7,972
Net Loss				(51,000)	(51,000)
Balance at end at Dec. 31, 2019	$ 30	$ 270,682	$ 37	$ (157,848)	$ 112,901
Balance at end (in shares) at Dec. 31, 2019	29,792,922