Quarterly report pursuant to Section 13 or 15(d)

Capital Structure - Additional Information (Detail)

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Capital Structure - Additional Information (Detail) - USD ($)
1 Months Ended 6 Months Ended
Jun. 30, 2017
Jan. 31, 2017
Jul. 27, 2016
Nov. 02, 2015
Jun. 12, 2015
Jan. 31, 2016
Aug. 31, 2014
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Class of Stock [Line Items]                    
Common stock, shares authorized 200,000,000             200,000,000   100,000,000
Common stock, par value $ 0.0001             $ 0.0001   $ 0.0001
IPO, closing period               2014-08    
Proceeds from exercise of warrants                 $ 16,000  
Net proceeds from initial public offering             $ 35,000,000      
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                  
Private Placement [Member]                    
Class of Stock [Line Items]                    
Number of shares issued         4,728,128          
Warrants to purchase shares of common stock 189,126       2,364,066     189,126    
Aggregate gross sales proceeds from common stock         $ 20,000,000          
Net proceeds received         $ 18,300,000          
Warrant exercise price per share $ 4.65       $ 8.00     $ 4.65    
Warrants expiration period         3 years          
Warrant expiration date               Jun. 11, 2020    
At the Market Equity Offering Program [Member] | Maximum [Member] | Cowen and Company, LLC [Member]                    
Class of Stock [Line Items]                    
Aggregate gross sales proceeds from common stock           $ 30,000,000        
Follow-on Offering [Member]                    
Class of Stock [Line Items]                    
Number of shares issued     14,000,000              
Warrants to purchase shares of common stock     14,000,000              
Aggregate gross sales proceeds from common stock     $ 35,000,000              
Net proceeds received     $ 32,000,000              
Warrant exercise price per share     $ 3.00              
Follow-on Offering [Member] | CMPO Warrants [Member]                    
Class of Stock [Line Items]                    
Warrants to purchase shares of common stock     14,000,000              
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              
Class A Warrants [Member]                    
Class of Stock [Line Items]                    
Warrant expiration date               Feb. 01, 2017    
Warrants exercised   0                
Class A Warrants [Member] | Initial Public Offering [Member]                    
Class of Stock [Line Items]                    
Warrant exercise price per share             $ 4.80      
Representative's Warrant [Member]                    
Class of Stock [Line Items]                    
Warrants to purchase shares of common stock 206,410             206,410    
Warrant exercise price per share $ 7.50             $ 7.50    
Warrant expiration date               Jul. 28, 2019    
Class of warrant purchase percentage 3.00%             3.00%    
Warrant exercisable period               180 days    
Class B Warrants [Member]                    
Class of Stock [Line Items]                    
Warrant expiration date               Nov. 02, 2015    
Warrants exercised       4,812,328            
Common stock shares issued upon exercise of warrants       2,406,164            
Proceeds from exercise of warrants       $ 9,600,000            
Class B Warrants [Member] | Initial Public Offering [Member]                    
Class of Stock [Line Items]                    
Warrant exercise price per share             $ 4.00