Quarterly report pursuant to Section 13 or 15(d)

Capital Structure - Additional Information (Detail)

v3.19.1
Capital Structure - Additional Information (Detail) - USD ($)
3 Months Ended 13 Months Ended
Aug. 03, 2018
Jul. 25, 2017
Jul. 27, 2016
Jun. 12, 2015
Aug. 01, 2014
Mar. 31, 2019
Mar. 31, 2018
Jun. 30, 2014
Dec. 31, 2018
Class of Stock [Line Items]                  
Common stock, shares authorized           200,000,000     200,000,000
Common stock, par value           $ 0.0001     $ 0.0001
Initial public offering, closing date           Aug. 01, 2014      
Number of warrants or rights outstanding           30,987,114     31,243,026
Common stock, voting rights           The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings.      
Dividends declared or paid           $ 0      
8.00% Convertible Notes due May 31, 2015 [Member]                  
Class of Stock [Line Items]                  
Convertible Notes, principal amount               $ 15,000,000  
Convertible Notes, interest rate               8.00%  
Convertible Notes, due date               May 31, 2015  
2016 Warrants [Member]                  
Class of Stock [Line Items]                  
Number of warrants or rights outstanding           14,000,000     14,000,000
2017 Warrants [Member]                  
Class of Stock [Line Items]                  
Number of warrants or rights outstanding           15,996,450     15,996,450
Private Placement [Member]                  
Class of Stock [Line Items]                  
Number of shares issued       4,728,128          
Net proceeds received       $ 18,300,000          
Warrants to purchase shares of common stock       2,364,066   189,126      
Warrant exercise price per share       $ 8.00   $ 4.65      
Private placement, securities description           Each investor received one share of common stock and a warrant to purchase one-half share of common stock at a price of $4.23 per common share purchased.      
Exercise price per common share       $ 4.23          
Class of warrant purchase percentage           4.00%      
Warrant expiration date           Jun. 11, 2020      
Initial Public Offering [Member]                  
Class of Stock [Line Items]                  
Conversion of Convertible Notes together with accrued and unpaid interest into common stock, shares         5,109,988        
Follow-on Offering [Member]                  
Class of Stock [Line Items]                  
Number of shares issued 5,750,000 32,000,000 14,000,000            
Public offering price, per unit $ 2.00                
Net proceeds received $ 10,400,000 $ 37,100,000 $ 32,000,000            
Warrants to purchase shares of common stock   16,000,000 14,000,000            
Aggregate gross sales proceeds from common stock   $ 40,000,000 $ 35,000,000            
Warrant exercise price per share   $ 1.55 $ 3.00            
Follow-on Offering [Member] | CMPO Warrants [Member]                  
Class of Stock [Line Items]                  
Warrants to purchase shares of common stock   16,000,000 14,000,000            
Follow-on Offering [Member] | 2016 Warrants [Member]                  
Class of Stock [Line Items]                  
Warrant exercise price per share     $ 3.00            
Warrant expiration term     5 years            
Fair value of warrants     $ 18,600,000            
Issuance costs allocated to warrants     $ 1,600,000            
Follow-on Offering [Member] | 2017 Warrants [Member]                  
Class of Stock [Line Items]                  
Warrants to purchase shares of common stock             2,500    
Warrant exercise price per share   $ 1.55              
Warrant expiration term   5 years              
Fair value of warrants   $ 12,400,000              
Issuance costs allocated to warrants   $ 900,000              
Note Warrants [Member]                  
Class of Stock [Line Items]                  
Warrant exercise price per share         $ 3.00        
Warrant expiration term           5 years      
Number of warrants or rights outstanding         3,321,416 414,790     670,702
Class of warrant or rights, expired           2,645,176 255,912    
Representative's Warrant [Member]                  
Class of Stock [Line Items]                  
Warrants to purchase shares of common stock           206,410      
Warrant exercise price per share           $ 7.50      
Class of warrant purchase percentage           3.00%      
Warrant expiration date           Jul. 28, 2019      
Warrant exercisable period           180 days      
Number of warrants or rights outstanding           206,410     206,410