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Stockholders' Equity - Additional Information (Detail) - $ / shares
Jan. 22, 2018
Dec. 31, 2017
Dec. 31, 2016
Class of Warrant or Right [Line Items]      
Preferred stock, shares authorized   2,000,000 2,000,000
Preferred stock, par value   $ 0.001 $ 0.001
Preferred stock, shares outstanding   0 0
Preferred stock, shares issued   0 0
Subsequent Event      
Class of Warrant or Right [Line Items]      
Preferred stock, par value $ 0.001    
Number of rights issued per common stock (in shares) 1    
Exercise price per share $ 10.00    
Number of preferred shares issued from exercise of right (in shares) 0.001