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Organization - Additional Information (Detail) - USD ($)
9 Months Ended
Oct. 05, 2017
Sep. 30, 2017
Oct. 30, 2017
Sep. 14, 2016
Subsequent Event [Member]        
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]        
Securities remained available for issuance under the Company's shelf registration     $ 178,000,000  
IPO [Member] | Subsequent Event [Member]        
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]        
Initial public offering, Number of shares 11,129,032      
Initial public offering, Price per share $ 15.50      
Initial public offering, Gross proceeds $ 172,000,000      
Initial public offering, Net proceeds $ 162,000,000      
Over-Allotment Option [Member] | Subsequent Event [Member]        
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]        
Initial public offering, Number of shares 1,451,613      
ITI Limited [Member] | Intellectual Property [Member]        
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]        
Finite lived intangible assets transactional gain   $ 125,000,000    
Maximum [Member]        
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]        
Universal shelf registration statement, effective date value       $ 350,000,000