Annual report pursuant to Section 13 and 15(d)

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

v3.10.0.1
Long-Term Debt and Notes Payable - Narrative (Details)
12 Months Ended
Dec. 31, 2018
USD ($)
fiscal_quarter
Feb. 16, 2018
USD ($)
Sep. 26, 2014
USD ($)
Debt Instrument      
Actual leverage ratio at end of period 2.04    
Amended And Restated Credit Agreement      
Debt Instrument      
Permitted leverage ratio 3.75    
Leverage ratio increase, duration of permitted following acquisition (in fiscal quarters) | fiscal_quarter 4    
Amended And Restated Credit Agreement | 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 1.00%    
Line of Credit | Revolving Credit Facility | LIBOR | Maximum      
Debt Instrument      
Interest rate on revolving credit at LIBOR rate 1.50%    
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility      
Debt Instrument      
Maximum borrowing capacity     $ 350,000,000
Optional increase in maximum borrowing capacity     $ 150,000,000
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility | Minimum      
Debt Instrument      
Commitment fee (percentage) 0.10%    
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility | Maximum      
Debt Instrument      
Commitment fee (percentage) 0.20%    
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility | LIBOR | Minimum      
Debt Instrument      
Interest rate on revolving credit at LIBOR rate 1.00%    
Line of Credit | Fourth Amended and Restated Credit Agreement | Revolving Credit Facility | LIBOR | Maximum      
Debt Instrument      
Interest rate on revolving credit at LIBOR rate 1.50%    
Line of Credit | Fifth Amended and Restated Credit Agreement | Revolving Credit Facility      
Debt Instrument      
Maximum borrowing capacity   $ 500,000,000  
Optional increase in maximum borrowing capacity   $ 150,000,000  
Outstanding letters of credit on revolving credit facility $ 227,000,000.0    
Revolving line of credit 271,900,000    
Line of Credit | Fifth Amended and Restated Credit Agreement | Letter of Credit      
Debt Instrument      
Credit facility allocation 20,000,000    
Outstanding letters of credit $ 1,100,000