Annual report pursuant to Section 13 and 15(d)

Stock Warrants (Additional Information) (Detail)

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Stock Warrants (Additional Information) (Detail) - USD ($)
1 Months Ended 12 Months Ended
Dec. 19, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Class of Warrant or Right [Line Items]        
Weighted average term of warrants   3 years 1 month 6 days 1 year 3 months 18 days 2 years 3 months 18 days
Weighted average exercise price of warrants per share   $ 6.44 $ 2.41 $ 2.43
Class Of Warrant Or Right Issued 1,033,062      
Class of Warrant or Right, Number of Securities Called by Warrants or Rights 1,033,058     3,559,783
Stock Issued During Period, Shares, Warrant Exercised   168,000 74,621  
Proceeds from Issuance of Warrants       $ 1,272,627
Class Of Warrant Exercised In Cashless Basis   250,009 111,232 4,178,267
Class Of Warrant Exercised In Cash Basis       568,488
Warrants 1        
Class of Warrant or Right [Line Items]        
Stock Issued During Period, Shares, Warrant Exercised     60,750  
Class Of Warrant Exercised In Cash Basis     22,000