Quarterly report pursuant to Section 13 or 15(d)

Long-term Debt (Details)

v3.8.0.1
Long-term Debt (Details)
3 Months Ended
Sep. 13, 2016
USD ($)
Mar. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Oct. 26, 2017
USD ($)
Long-term debt        
Net unamortized debt issuance costs   $ (8,720,000) $ (9,000,000)  
Long-term debt, net   1,301,280,000 1,196,000,000  
Revolving credit facility        
Long-term debt        
Long-term debt   $ 660,000,000 $ 555,000,000  
Maximum borrowing capacity       $ 1,500,000,000
Weighted average interest rate (as a percent)   2.95% 2.81%  
Revolving credit facility | Minimum        
Long-term debt        
Commitment fees on the unused portion (as a percent)   0.25%    
Commitment fees on the unused portion during investment grade period (as a percent)   0.175%    
Revolving credit facility | Maximum        
Long-term debt        
Commitment fees on the unused portion (as a percent)   0.375%    
Commitment fees on the unused portion during investment grade period (as a percent)   0.375%    
Revolving credit facility | Investment Grade Period | Minimum        
Long-term debt        
Margin rates   12.5    
Revolving credit facility | Investment Grade Period | Maximum        
Long-term debt        
Margin rates   200    
Revolving credit facility | Not Investment Grade Period | Minimum        
Long-term debt        
Margin rates   25    
Revolving credit facility | Not Investment Grade Period | Maximum        
Long-term debt        
Margin rates   225    
Letter of credit        
Long-term debt        
Outstanding letters of credit   $ 0 $ 0  
5.375% Senior Notes due 2024        
Long-term debt        
Long-term debt   $ 650,000,000 $ 650,000,000  
Face amount $ 650,000,000      
Interest rate (as a percent) 5.375%      
Debt instrument redemption percentage upon change of control 101.00%      
5.375% Senior Notes due 2024 | Maximum        
Long-term debt        
Percent of aggregate principal amount that can be redeemed 35.00%      
5.375% Senior Notes due 2024 | Prior to September 15, 2019        
Long-term debt        
Debt instrument redemption percentage 105.375%      
Debt instrument redemption percentage with payment of premium and interest 100.00%      
5.375% Senior Notes due 2024 | On or after September 15, 2019        
Long-term debt        
Debt instrument redemption percentage 104.031%      
5.375% Senior Notes due 2024 | On or after September 15, 2022        
Long-term debt        
Debt instrument redemption percentage 100.00%