Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Related Party Transaction (Detail)

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Related Party Transaction (Detail) - USD ($)
3 Months Ended 6 Months Ended
Jun. 01, 2018
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Related Party Transaction [Line Items]            
Stock options, granted (in shares)       2,168,602    
Weighted average exercise price, granted (in dollars per share)       $ 8.34    
Executive Vice President            
Related Party Transaction [Line Items]            
Fees for performing duties   $ 41,000 $ 52,000 $ 87,000 $ 118,000  
Related party transaction compensation for services on board   $ 12,500 $ 12,500 $ 25,000 $ 12,500  
Stock options, granted (in shares) 3,017          
Weighted average exercise price, granted (in dollars per share) $ 11.60          
Fair market value of options granted (in dollars per share) $ 3.74          
Restricted Stock            
Related Party Transaction [Line Items]            
Restricted stock granted (in shares)       41,382    
Restricted stock fair value (in dollars per share)   $ 7.99   $ 7.99   $ 7.27
Restricted Stock | Executive Vice President            
Related Party Transaction [Line Items]            
Restricted stock granted (in shares) 6,897          
Restricted stock fair value (in dollars per share) $ 11.60