Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Equity - Additional Information (Detail)

v3.19.1
Shareholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
 1 Months Ended
May 10, 2019
Mar. 25, 2019
Nov. 08, 2017
Jan. 31, 2019
Series C Preferred Stock [Member]        
Class Of Stock [Line Items]        
Preferred stock dividend rate     12.00%  
Preferred stock issued as dividend       12.208
Series C Preferred Stock [Member] | Subsequent Event [Member]        
Class Of Stock [Line Items]        
Preferred stock dividend rate 20.00%      
Underwritten Public Offering [Member]        
Class Of Stock [Line Items]        
Proceeds from public offering   $ 12.5    
Share price per unit   $ 0.75    
Warrants exercise price per share   $ 0.75    
Underwritten Public Offering [Member] | Common Stock [Member]        
Class Of Stock [Line Items]        
Number of common stock issued in offering   16,666,668    
Underwritten Public Offering [Member] | Short-term Warrants [Member]        
Class Of Stock [Line Items]        
Warrants exercise price per share   $ 0.75    
Exercisable term of warrants   18 months    
Trading period   21 days    
Underwritten Public Offering [Member] | Short-term Warrants [Member] | Maximum [Member]        
Class Of Stock [Line Items]        
Shares of common stock callable by warrants issued   8,333,334    
Underwritten Public Offering [Member] | Long-term Warrants [Member]        
Class Of Stock [Line Items]        
Warrants exercise price per share   $ 0.90    
Term of warrants   5 years    
Underwritten Public Offering [Member] | Long-term Warrants [Member] | Maximum [Member]        
Class Of Stock [Line Items]        
Shares of common stock callable by warrants issued   8,333,334    
Underwriter [Member] | Common Stock [Member] | Maximum [Member]        
Class Of Stock [Line Items]        
Number of shares of stock available for purchase   2,500,000    
Underwriter [Member] | Short-term Warrants [Member]        
Class Of Stock [Line Items]        
Number of warrants available for purchase   1,250,000    
Underwriter [Member] | Long-term Warrants [Member]        
Class Of Stock [Line Items]        
Number of warrants available for purchase   1,250,000    
Underwriter [Member] | Short-term Warrants [Member]        
Class Of Stock [Line Items]        
Number of warrants purchased in period   1,250,000    
Underwriter [Member] | Long-term Warrants [Member]        
Class Of Stock [Line Items]        
Number of warrants purchased in period   1,250,000