Annual report pursuant to Section 13 and 15(d)

Stock Warrants (Additional Information) (Detail)

v3.19.1
Stock Warrants (Additional Information) (Detail) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Jan. 24, 2018
Dec. 19, 2017
Class of Warrant or Right [Line Items]          
Weighted average term of warrants 1 year 2 months 12 days 3 years 1 month 6 days 1 year 3 months 18 days    
Class of Warrant or Right Weighted Average Exercise Price of Warrants or Rights $ 8.61        
Weighted average exercise price of warrants per share   $ 6.44 $ 2.41    
Class Of Warrant Or Right Issued 1,200,000        
Class of Warrant or Right, Number of Securities Called by Warrants or Rights 1,200,000     1,200,000 1,033,058
Stock Issued During Period, Shares, Warrant Exercised 66,710 168,203 74,620    
Class Of Warrant Exercised In Cashless Basis 96,350 250,009 111,232    
Class Of Warrant Exercised In Cash Basis 17,500        
Warrants 1          
Class of Warrant or Right [Line Items]          
Class Of Warrant Exercised In Cash Basis 17,500   22,000    
Proceeds from Issuance of Warrants $ 39,373   $ 60,751