Annual report pursuant to Section 13 and 15(d)

Subsequent Events - Additional Information (Detail)

v3.19.1
Subsequent Events - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
 1 Months Ended 12 Months Ended
Mar. 25, 2019
Jul. 17, 2018
Apr. 06, 2018
Jan. 31, 2019
Dec. 31, 2018
Subsequent Event [Line Items]          
Proceeds from public offering   $ 13.8     $ 13.8
Number of common stock issued in offering     900,000    
Share price per unit     $ 2.00    
Warrants exercise price per share     $ 2.00    
Exercisable term of warrants     6 months    
Common Stock [Member]          
Subsequent Event [Line Items]          
Proceeds from public offering   $ 2.3      
Number of common stock issued in offering   4,436,000     4,436,000
Share price per unit   $ 3.00      
Trading period   30 days      
Underwriter [Member]          
Subsequent Event [Line Items]          
Number of common stock issued in offering   1,800,000      
Subsequent Event [Member] | Underwritten Public Offering [Member]          
Subsequent Event [Line Items]          
Proceeds from public offering $ 12.5        
Share price per unit $ 0.75        
Warrants exercise price per share $ 0.75        
Subsequent Event [Member] | Underwritten Public Offering [Member] | Common Stock [Member]          
Subsequent Event [Line Items]          
Number of common stock issued in offering 16,666,668        
Subsequent Event [Member] | Underwritten Public Offering [Member] | Short-term Warrants [Member]          
Subsequent Event [Line Items]          
Warrants exercise price per share $ 0.75        
Exercisable term of warrants 18 months        
Trading period 21 days        
Subsequent Event [Member] | Underwritten Public Offering [Member] | Short-term Warrants [Member] | Maximum [Member]          
Subsequent Event [Line Items]          
Shares of common stock callable by warrants issued 8,333,334        
Subsequent Event [Member] | Underwritten Public Offering [Member] | Long-term Warrants [Member]          
Subsequent Event [Line Items]          
Warrants exercise price per share $ 0.90        
Term of warrants 5 years        
Subsequent Event [Member] | Underwritten Public Offering [Member] | Long-term Warrants [Member] | Maximum [Member]          
Subsequent Event [Line Items]          
Shares of common stock callable by warrants issued 8,333,334        
Subsequent Event [Member] | Underwriter [Member] | Common Stock [Member] | Maximum [Member]          
Subsequent Event [Line Items]          
Number of common stock issued in offering 2,500,000        
Subsequent Event [Member] | Underwriter [Member] | Short-term Warrants [Member]          
Subsequent Event [Line Items]          
Shares of common stock callable by warrants issued 1,250,000        
Subsequent Event [Member] | Underwriter [Member] | Long-term Warrants [Member]          
Subsequent Event [Line Items]          
Shares of common stock callable by warrants issued 1,250,000        
Subsequent Event [Member] | Underwriter | Short-term Warrants [Member]          
Subsequent Event [Line Items]          
Shares of common stock callable by warrants issued 1,250,000        
Subsequent Event [Member] | Underwriter | Long-term Warrants [Member]          
Subsequent Event [Line Items]          
Shares of common stock callable by warrants issued 1,250,000        
Series C Preferred Stock [Member] | Subsequent Event [Member]          
Subsequent Event [Line Items]          
Preferred stock issued as dividend       12.208