Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity - Warrants - Additional Information (Detail)

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Shareholders' Equity - Warrants - Additional Information (Detail) - $ / shares
Jul. 17, 2018
Apr. 06, 2018
Dec. 31, 2018
Class of Stock [Line Items]      
Share price per unit   $ 2.00  
Warrants exercise price per share   $ 2.00  
Warrants granted 13,800,000 900,000  
Class of warrants exercised     9,505,500
Common stock issued during period   900,000  
Non-exercisable term of warrants   6 months  
Term of warrants   5 years  
Capital Unit, Class A [Member]      
Class of Stock [Line Items]      
Share price per unit $ 1.00    
Number of common shares issued with each capital unit 1    
Common stock warrants term 7 years    
Number of warrants issued with each capital unit 1    
Warrants exercise price per share $ 1.00    
Capital Unit, Class B [Member]      
Class of Stock [Line Items]      
Share price per unit $ 1.00    
Capital Unit, Class B [Member] | Series D Preferred Stock [Member]      
Class of Stock [Line Items]      
Number of warrants issued with each capital unit 1    
Number of preferred shares issued with each capital unit 1    
Shares of common stock callable by warrants issued 1