Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.7.0.1
Organization and Description of Business - Additional Information (Detail) - Follow-on Offering [Member] - USD ($)
$ / shares in Units, $ in Millions
Jul. 25, 2017
Jul. 27, 2016
Organization And Description Of Business [Line Items]    
Number of shares issued   14,000,000
Warrants to purchase shares of common stock   14,000,000
Warrant exercise price per share   $ 3.00
Public offering price, per unit   $ 2.50
Net proceeds received   $ 32.0
Subsequent Event [Member]    
Organization And Description Of Business [Line Items]    
Number of shares issued 32,000,000  
Warrants to purchase shares of common stock 16,000,000  
Warrant exercise price per share $ 1.55  
Public offering price, per unit $ 1.25  
Net proceeds received $ 36.9