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Stockholders' Equity - Additional Information (Detail) - $ / shares
Dec. 31, 2018
Aug. 06, 2018
Jan. 22, 2018
Dec. 31, 2017
Class of Stock [Line Items]        
Preferred stock, shares authorized (in shares) 2,000,000     2,000,000
Preferred stock, par value (in dollars per share) $ 0.001     $ 0.001
Preferred stock, shares outstanding (in shares) 0     0
Preferred stock, shares issued (in shares) 0     0
Number of rights issued per common stock (in shares)     1  
Exercise price per share (in dollars per share)   $ 2.52    
Series D Preferred Stock        
Class of Stock [Line Items]        
Preferred stock, shares authorized (in shares) 150,000      
Preferred stock, par value (in dollars per share)     $ 0.001  
Exercise price per share (in dollars per share)     $ 10.00  
Number of preferred shares issued from exercise of right (in shares)     0.001