Warrants -Summary of Outstanding Warrants (Details)	9 Months Ended
	Sep. 30, 2019 $ / shares shares
Convertible Note Warrants
Class Of Warrant Or Right [Line Items]
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]
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]
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]
Shares of Common Stock Underlying Warrants | shares	5,411,687
Exercise Price/Share | $ / shares	$ 0.01
Series E Redeemable Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants | shares	28,713
Exercise Price/Share | $ / shares	$ 23.51
Expiration Date	2024