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Summary of Warrant Activity (Detail) - $ / shares
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Warrants And Rights Note Disclosure [Abstract]    
Number of Shares Underlying Warrants, Outstanding 7,857 10,194
Number of Shares Underlying Warrants, Forfeited (7,772) (2,337)
Number of Shares Underlying Warrants, Outstanding 85 7,857
Warrants Outstanding, Weighted Average Exercise Price $ 53.61 $ 155.73
Warrants Forfeited, Weighted Average Exercise Price 49.91 499.50
Warrants Outstanding, Weighted Average Exercise Price $ 392.70 $ 53.61