Annual report pursuant to Section 13 and 15(d)

Long-Term Debt and Notes Payable - Narrative (Detail)

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Long-Term Debt and Notes Payable - Narrative (Detail)
12 Months Ended
Dec. 31, 2017
USD ($)
fiscal_quarter
Feb. 16, 2018
USD ($)
Sep. 30, 2017
USD ($)
Dec. 31, 2016
USD ($)
Sep. 26, 2014
USD ($)
Debt Instrument          
Actual leverage ratio at end of period 2.91        
Amended And Restated Credit Agreement          
Debt Instrument          
Permitted leverage ratio 3.5        
Leverage ratio increase, duration of permitted following acquisition (in fiscal quarters) | fiscal_quarter 2        
Minimum interest coverage ratio 3.0        
Amended And Restated Credit Agreement | Maximum          
Debt Instrument          
Permitted leverage ratio 4.0        
Fifth Amended And Restated Credit Agreement [Member]          
Debt Instrument          
Permitted leverage ratio 3.75        
Leverage ratio increase, duration of permitted following acquisition (in fiscal quarters) | fiscal_quarter 4        
Fifth Amended And Restated Credit Agreement [Member] | Maximum          
Debt Instrument          
Permitted leverage ratio 4.50        
Line of Credit | Revolving Credit Facility | LIBOR | Minimum          
Debt Instrument          
Interest rate on revolving credit at LIBOR rate 1.375%        
Line of Credit | Revolving Credit Facility | LIBOR | Maximum          
Debt Instrument          
Interest rate on revolving credit at LIBOR rate 2.25%        
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility          
Debt Instrument          
Term loan $ 262,000,000     $ 136,000,000  
Optional increase in maximum borrowing capacity         $ 150,000,000
Maximum borrowing capacity         $ 350,000,000
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility | Minimum          
Debt Instrument          
Commitment fee (percentage) 0.175%        
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility | Maximum          
Debt Instrument          
Commitment fee (percentage) 0.35%        
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility | LIBOR | Minimum          
Debt Instrument          
Interest rate on revolving credit at LIBOR rate 1.375%        
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility | LIBOR | Maximum          
Debt Instrument          
Interest rate on revolving credit at LIBOR rate 2.25%        
Line of Credit | Amended And Restated Credit Agreement | Letter of Credit          
Debt Instrument          
Outstanding letters of credit     $ 1,100,000    
Line of Credit | Fifth Amended And Restated Credit Agreement [Member] | Revolving Credit Facility          
Debt Instrument          
Revolving line of credit $ 236,900,000        
Outstanding letters of credit on revolving credit facility $ 262,000,000        
Line of Credit | Fifth Amended And Restated Credit Agreement [Member] | Revolving Credit Facility | Minimum          
Debt Instrument          
Commitment fee (percentage) 0.10%        
Line of Credit | Fifth Amended And Restated Credit Agreement [Member] | Revolving Credit Facility | Maximum          
Debt Instrument          
Commitment fee (percentage) 0.20%        
Line of Credit | Fifth Amended And Restated Credit Agreement [Member] | Revolving Credit Facility | LIBOR | Minimum          
Debt Instrument          
Interest rate on revolving credit at LIBOR rate 1.00%        
Line of Credit | Fifth Amended And Restated Credit Agreement [Member] | Revolving Credit Facility | LIBOR | Maximum          
Debt Instrument          
Interest rate on revolving credit at LIBOR rate 1.50%        
Subsequent Event | Line of Credit | Fifth Amended And Restated Credit Agreement [Member] | Revolving Credit Facility          
Debt Instrument          
Optional increase in maximum borrowing capacity   $ 150,000,000      
Maximum borrowing capacity   500,000,000      
Subsequent Event | Line of Credit | Fifth Amended And Restated Credit Agreement [Member] | Letter of Credit          
Debt Instrument          
Credit facility allocation   $ 20,000,000