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Stock-Based Compensation - Summary of Stock Options Activity (Details) - Options to purchase Common Stock - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Number of Options      
Beginning balance (in shares) 83,345 62,376  
Granted (in shares) 971,313 52,791  
Forfeitures (in shares) (36,148) (31,590)  
Expired (in shares) (3,092) (232)  
Ending balance (in shares) 1,015,418 83,345 62,376
Vested and exercisable (in shares) 71,518    
Weighted-Average Exercise Price Per Share      
Outstanding (in dollars per share) $ 146.09 $ 291.10  
Granted (in dollars per share) 2.49 18.69  
Forfeited (in dollars per share) 26.55 219.03  
Expired (in dollars per share) 220.27 216.00  
Outstanding (in dollars per share) 12.77 $ 146.09 $ 291.10
Vested and exercisable (in dollars per share) $ 147.46    
Intrinsic value, outstanding $ 0 $ 0 $ 0
Intrinsic value, vested and exercisable $ 0    
Weighted average remaining contract term, outstanding 9 years 20 days 7 years 3 months 10 days 7 years 1 month 10 days
Weighted average remaining contractual term, exercisable 4 years 9 months