Warrants -Summary of Outstanding Warrants (Details) - $ / shares	9 Months Ended
	Sep. 30, 2020	Jun. 24, 2020
SVB Term Loan
Class Of Warrant Or Right [Line Items]
Warrant Issuance Date	2020-06
Shares of Common Stock Underlying Warrants	643,413
Exercise Price/Share	$ 0.7771	$ 0.7771
Expiration Date	2030
Convertible Note Warrants
Class Of Warrant Or Right [Line Items]
Warrant Issuance Date	2014-12
Shares of Common Stock Underlying Warrants	144,772
Exercise Price/Share	$ 14.00
Expiration Date	2022
Common Stock Warrants
Class Of Warrant Or Right [Line Items]
Warrant Issuance Date	2016-03
Shares of Common Stock Underlying Warrants	45,307
Exercise Price/Share	$ 2.76
Expiration Date	2026
Common Stock Tranche one
Class Of Warrant Or Right [Line Items]
Warrant Issuance Date	2018-03
Shares of Common Stock Underlying Warrants	18,123
Exercise Price/Share	$ 7.73
Expiration Date	2028
Pre-funded Warrants
Class Of Warrant Or Right [Line Items]
Warrant Issuance Date	2019-09
Shares of Common Stock Underlying Warrants	2,234,925
Exercise Price/Share	$ 0.01
Series E Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Warrant Issuance Date	2014-08
Shares of Common Stock Underlying Warrants	28,713
Exercise Price/Share	$ 23.51
Expiration Date	2024