Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity - Additional Information (Detail)

v3.10.0.1
Shareholders' Equity - Additional Information (Detail)
 1 Months Ended 12 Months Ended
Aug. 31, 2018
USD ($)
$ / shares
shares
Sep. 29, 2018
USD ($)
vote
$ / shares
shares
Sep. 30, 2017
USD ($)
$ / shares
shares
Sep. 24, 2016
USD ($)
Sep. 24, 2011
USD ($)
Class of Stock [Line Items]          
Preferred stock authorized (in shares)   1,000,000 1,000,000    
Preferred stock, par value (in usd per share) | $ / shares   $ 0.01 $ 0.01    
Preferred stock, shares outstanding   0 0    
Proceeds from issuance of common stock, net of offering costs | $   $ 195,631,000 $ 0 $ 324,000  
Common stock          
Class of Stock [Line Items]          
Common stock authorized (in shares)   80,000,000 80,000,000    
Common stock, par value (in usd per share) | $ / shares   $ 0.01 $ 0.01    
Common stock, shares outstanding   12,145,135 12,160,023    
Authorized amount to repurchase stock | $         $ 100,000,000
Aggregate stock repurchased shares   7,900,000      
Aggregate stock repurchased value | $   $ 65,000,000      
Class A common stock          
Class of Stock [Line Items]          
Common stock authorized (in shares)   100,000,000 100,000,000    
Common stock, par value (in usd per share) | $ / shares   $ 0.01 $ 0.01    
Common stock, shares outstanding   43,953,265 38,019,736    
Shares issued and sold (in shares) 5,500,000        
Shares issued and sold (in dollars per share) | $ / shares $ 37.00        
Shares issued upon exercise of option (in shares) 550,000        
Proceeds from issuance of common stock, net of offering costs | $ $ 195,600,000        
Class B stock          
Class of Stock [Line Items]          
Common stock authorized (in shares)   3,000,000 3,000,000    
Common stock, par value (in usd per share) | $ / shares   $ 0.01 $ 0.01    
Common stock, shares outstanding   1,652,262 1,652,262    
Percentage of vote cast for shares (percent)   49.00%      
Convertible shares conversion ratio   1      
Minimum | Class B stock          
Class of Stock [Line Items]          
Number of voting powers | vote   1      
Maximum | Class B stock          
Class of Stock [Line Items]          
Number of voting powers | vote   10