STOCKHOLDERS' EQUITY-Common stock and warrants (Details)	Oct. 08, 2019 series $ / shares shares	Sep. 30, 2021 $ / shares shares	Dec. 31, 2020 $ / shares shares
Stockholders' equity
Common stock, par value (in dollars per share) | $ / shares		$ 0.0001	$ 0.0001
Annualized Rate Of Increase To The Strike Price Of Warrants Issued	6.75
Warrant term (in years)	3 years
Authorized shares of common stock, after amendment of certificate of incorporation		100,000,000	100,000,000
Number of series of warrants | series	3
Number of shares of common stock that can be purchased from warrants	1
Series A Warrants
Stockholders' equity
Number of warrants issued		1,800,000
Warrants issued	1,798,322
Exercise price (in dollars per share) | $ / shares	$ 40.17	$ 44.36
Series B Warrants
Stockholders' equity
Number of warrants issued		2,200,000
Warrants issued	2,247,985
Exercise price (in dollars per share) | $ / shares	$ 48.28	$ 53.59
Series C Warrants
Stockholders' equity
Number of warrants issued		2,900,000
Warrants issued	2,890,271
Exercise price (in dollars per share) | $ / shares	$ 60.45	$ 67.44