Quarterly report pursuant to Section 13 or 15(d)

Public Offering - Additional Information (Detail)

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Public Offering - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 9 Months Ended
Jul. 24, 2015
Jul. 06, 2015
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Initial Public Offering And Issuance Of Senior Unsecured Notes [Line Items]            
Number of shares, Options exercised     0 0 0 0
Gross proceeds from issuance initial public offering   $ 28.3        
Net proceeds from issuance initial public offering   $ 25.8        
IPO [Member]            
Initial Public Offering And Issuance Of Senior Unsecured Notes [Line Items]            
Stock issued   9,090,909        
Sales of common stock, price per share $ 2.75 $ 2.75        
Number of shares, Options exercised 1,211,827