Warrants - Issuable Shares of Common Stock Related to Unexercised Warrants Outstanding (Details)	Mar. 31, 2020 $ / shares shares
Total
Class of Stock [Line Items]
Shares	5,122,183
Hercules Warrant
Class of Stock [Line Items]
Shares	41,177
Exercise price (in dollars per share) | $ / shares	$ 6.80
2018 Public Offering Warrants
Class of Stock [Line Items]
Shares	3,616,944
Exercise price (in dollars per share) | $ / shares	$ 9.60
Private Placement Warrants
Class of Stock [Line Items]
Shares	932,812
Exercise price (in dollars per share) | $ / shares	$ 4.52
Pre-Funded Warrants
Class of Stock [Line Items]
Shares	531,250
Exercise price (in dollars per share) | $ / shares	$ 0.08