Redeemable Convertible Preferred Stock and Stockholders’ Deficit - Warrants outstanding (Details)	Sep. 30, 2019 $ / shares shares
Redeemable Convertible Preferred Stock and Stockholders’ Deficit
Warrants outstanding	2,186,693
MidCap Credit Facility | Warrants
Redeemable Convertible Preferred Stock and Stockholders’ Deficit
Warrants outstanding	206,897
warrants exercise price | $ / shares	$ 1.16
Notes payable | Warrants
Redeemable Convertible Preferred Stock and Stockholders’ Deficit
Warrants outstanding	387,932
warrants exercise price | $ / shares	$ 1.16
Convertible promissory notes | Warrants
Redeemable Convertible Preferred Stock and Stockholders’ Deficit
Warrants outstanding	1,591,864
warrants exercise price | $ / shares	$ 1.16