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Summary of Warrant Activity (Detail) - $ / shares
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Warrants And Rights Note Disclosure [Abstract]    
Number of Shares Underlying Warrants, Outstanding 10,194 1,751,708
Number of Shares Underlying Warrants, Exercised   (1,735,419)
Number of Shares Underlying Warrants, Forfeited/Cancelled (2,337) (6,095)
Number of Shares Underlying Warrants, Outstanding 7,857 10,194
Warrants Outstanding, Weighted Average Exercise Price $ 155.73 $ 6.46
Warrants Exercised, Weighted Average Exercise Price   5.50
Warrants Forfeited/Cancelled, Weighted Average Exercise Price 499.50 5.50
Warrants Outstanding, Weighted Average Exercise Price $ 53.61 $ 155.73