Warrants -Summary of Outstanding Warrants (Details)	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Class Of Warrant Or Right [Line Items]
Exercise Price/Share	$ 7.73
Convertible Note Warrants
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants | shares	144,772
Exercise Price/Share	$ 14.00
Expiration Date	2022
Common Stock Warrants one
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants | shares	931
Exercise Price/Share	$ 6.45
Expiration Date	2019
Common Stock Warrants
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants | shares	45,307
Exercise Price/Share	$ 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	$ 7.73
Expiration Date	2028
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	$ 23.51
Expiration Date	2024