Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ (Deficit) Equity - USD ($) $ in Thousands	Common stock Initial Public Offering	Common stock Underwritten public offering	Common stock At-the-market offering	Common stock	Additional paid-in capital Initial Public Offering	Additional paid-in capital Underwritten public offering	Additional paid-in capital At-the-market offering	Additional paid-in capital	Accumulated other comprehensive loss [Member]	Accumulated deficit	Series A Preferred Stock	Series B Preferred Stock	Series C Preferred Stock	Series D Preferred Stock	Initial Public Offering	Underwritten public offering	At-the-market offering	Total
Beginning Balance at Dec. 31, 2016				$ 2						$ (115,111)	$ 28,979	$ 17,459	$ 36,678	$ 45,469				$ (115,109)
Beginning balance (in shares) at Dec. 31, 2016				2,315,496							15,700,001	6,021,363	8,605,944	12,420,262
Increase (Decrease) in Stockholders' Equity
Exercise of preferred stock warrants											$ 2,078		$ 138
Exercise of preferred stock warrants (in shares)											700,000		31,283
Exercise of common stock options and vesting restricted stock								$ 204										204
Exercise of common stock options and vesting restricted stock (in shares)				289,321
Issue of common stock, net	$ 5				$ 65,570									$ 8,423	$ 65,575
Issue of common stock, net (in shares)	4,916,480													2,113,902
Accretion of preferred stock to redemption value								(2,029)		(2,081)	$ 1,080	$ 840	$ 2,140	$ 50				(4,110)
Conversion of preferred stock to common stock				$ 15				143,319			$ (32,137)	$ (18,299)	$ (38,956)	$ (53,942)				143,334
Conversion of preferred stock to common stock (in shares)				14,185,744							(16,400,001)	(6,021,363)	(8,637,227)	(14,534,164)
Warrant Liability reclassified to equity upon IPO								823										823
Stock-based compensation expense								2,168										2,168
Net loss										(27,019)								(27,019)
Ending Balance at Dec. 31, 2017				$ 22				210,196		(144,352)								65,866
Ending Balance (in shares) at Dec. 31, 2017				21,707,041
Increase (Decrease) in Stockholders' Equity
Cumulative-effect adjustment for the adoption of ASC 606								141		(141)
Exercise of preferred stock warrants (in shares)				16,718
Exercise of common stock options and vesting restricted stock								1,871										1,871
Exercise of common stock options and vesting restricted stock (in shares)				645,277
Common stock issuance offering costs								(20)										(20)
Stock-based compensation expense								4,884										4,884
Net loss										(31,536)								(31,536)
Ending Balance at Dec. 31, 2018				$ 22				216,931		(175,888)								41,065
Ending Balance (in shares) at Dec. 31, 2018				22,369,036
Increase (Decrease) in Stockholders' Equity
Exercise of preferred stock warrants (in shares)				45,690
Exercise of common stock options and vesting restricted stock								2,820										2,820
Exercise of common stock options and vesting restricted stock (in shares)				550,734
Issue of common stock, net		$ 3	$ 2			$ 64,526	$ 48,017									$ 64,529	$ 48,019
Issue of common stock, net (in shares)		2,732,673	2,186,163
Issuance of shares for acquisition of Uman				$ 1				5,467										5,468
Issuance of shares for acquisition of Uman (in shares)				191,152
ESPP stock purchase								878										878
ESPP stock purchase (in shares)				36,753
Stock-based compensation expense								6,388										6,388
Cumulative translation adjustment																		(153)
Net loss										(40,796)								(40,796)
Ending Balance at Dec. 31, 2019				$ 28				$ 345,027	$ (153)	(216,244)								128,658
Ending Balance (in shares) at Dec. 31, 2019				28,112,201
Increase (Decrease) in Stockholders' Equity
Cumulative-effect adjustment for the adoption of ASC 606										$ 440								440
Accumulated other comprehensive income									$ (153)									$ (153)