Warrants - Additional Information (Details)			1 Months Ended		12 Months Ended
	Mar. 26, 2018 USD ($) $ / shares shares	Jan. 15, 2015 USD ($) $ / shares shares	Mar. 31, 2018 USD ($) $ / shares shares	Aug. 31, 2014 Institution	Dec. 31, 2019 $ / shares shares	Dec. 31, 2016 Institution	Sep. 30, 2019 $ / shares shares	Mar. 31, 2016 $ / shares shares	May 11, 2015 $ / shares shares	Aug. 22, 2014 $ / shares shares
MidCap Credit Facility
Class Of Warrant Or Right [Line Items]
Credit facility aggregate principal amount | $	$ 20,000,000
MidCap Credit Facility | MidCap Tranche 1
Class Of Warrant Or Right [Line Items]
Number of securities called by warrants | shares	18,123		18,123
Exercise price of warrants	$ 7.73		$ 7.73
Warrants to purchase of common stock expiration year	10 years		10 years
Credit facility aggregate principal amount | $	$ 7,000,000		$ 7,000,000
Private Placement | Institutional Accredited Investors
Class Of Warrant Or Right [Line Items]
Exercise price of warrants					$ 0.65		$ 0.65
Growth Term Loan
Class Of Warrant Or Right [Line Items]
Number of loan lending institutions | Institution				2		2
Series E Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Number of securities called by warrants | shares								5,317	23,396	2,512,562
Exercise price of warrants					$ 23.51			$ 23.51	$ 23.51	$ 0.2189
Warrants expiration date					Aug. 22, 2024
Common Stock Warrants one
Class Of Warrant Or Right [Line Items]
Number of securities called by warrants | shares								45,307
Exercise price of warrants								$ 2.759
Convertible Note Warrants
Class Of Warrant Or Right [Line Items]
Number of securities called by warrants | shares		9,311,586
Exercise price of warrants		$ 0.2189			$ 14.00
Warrants expiration date					Jan. 15, 2022
Aggregate consideration | $		$ 1,354
Convertible Note Warrants | IPO
Class Of Warrant Or Right [Line Items]
Number of securities called by warrants | shares									144,772
Exercise price of warrants									$ 14.00
Pre-funded Warrants
Class Of Warrant Or Right [Line Items]
Exercise price of warrants					$ 0.01
Pre-funded Warrants | Private Placement | Institutional Accredited Investors
Class Of Warrant Or Right [Line Items]
Number of securities called by warrants | shares					5,411,687		5,411,687
Exercise price of warrants					$ 0.64		$ 0.64
Issuance of warrants, shares | shares					5,411,687		5,411,687
Exercise price of warrants, exercisable subject to beneficial ownership limitations					$ 0.01		$ 0.01