Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt - Narrative (Details)

v3.10.0.1
Long-Term Debt - Narrative (Details) - USD ($)
6 Months Ended
Sep. 30, 2016
Feb. 29, 2016
Jun. 30, 2018
Dec. 31, 2017
Debt Instrument [Line Items]        
Long-term debt     $ 1,731,235,000 $ 1,718,297,000
Revolving Credit Facility        
Debt Instrument [Line Items]        
Line of credit     84,100,000  
Remaining borrowing capacity     210,900,000  
Deferred financing and unamortized discounts     $ 25,897,000  
LIBOR | Revolving Credit Facility        
Debt Instrument [Line Items]        
Commitment fee for line of credit     0.50%  
Principal Owner        
Debt Instrument [Line Items]        
Principal being treated as a capital contribution   $ 88,000,000    
Term Loan | Interest Rate Swap | Designated as Hedging Instrument        
Debt Instrument [Line Items]        
Fixed rate paid     7.98%  
Senior Notes 9.125 Percent Due 2020 | Senior Notes        
Debt Instrument [Line Items]        
Principal     $ 585,000,000  
Debt interest rate     9.125%  
Accumulated amortization, deferred financing costs     $ 4,718,000  
Long-term debt     580,282,000 580,026,000
Promissory Note Due 2020 | Promissory Note        
Debt Instrument [Line Items]        
Long-term debt   $ 12,000,000 12,000,000 12,000,000
Promissory Note Due 2020 | Promissory Note | Parent Company        
Debt Instrument [Line Items]        
Debt interest rate   12.50%    
Extinguishment of debt   $ 100,000,000    
Term Loan Due September 2022 | Term Loan        
Debt Instrument [Line Items]        
Principal $ 1,100,000,000   1,080,750,000  
Long-term debt     1,056,465,000 1,059,598,000
Debt discount on purchase price 1.50%      
Line of credit facility, periodic payment     $ 2,750,000  
Springing maturity period     181 days  
Term Loan Due September 2022 | Term Loan | LIBOR        
Debt Instrument [Line Items]        
Basis spread on variable debt     5.50%  
Floor on variable debt     1.00%  
Revolving Credit Facility Due 2021 | Revolving Credit Facility        
Debt Instrument [Line Items]        
Long-term debt     $ 82,488,000 $ 66,673,000
Maximum borrowing on line $ 295,000,000   $ 295,000,000  
Revolving Credit Facility Due 2021 | Revolving Credit Facility | LIBOR        
Debt Instrument [Line Items]        
Basis spread on variable debt     4.00%  
Floor on variable debt     1.00%