Warrants -Summary of Outstanding Warrants (Details)	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Convertible Note Warrants
Class Of Warrant Or Right [Line Items]
Warrant Issuance Date	2014-12
Shares of Common Stock Underlying Warrants | shares	144,772
Exercise Price/Share | $ / shares	$ 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 | shares	45,307
Exercise Price/Share | $ / shares	$ 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 | shares	18,123
Exercise Price/Share | $ / shares	$ 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 | shares	2,234,925
Exercise Price/Share | $ / shares	$ 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 | shares	28,713
Exercise Price/Share | $ / shares	$ 23.51
Expiration Date	2024