Annual report pursuant to Section 13 and 15(d)

Long-term Debt - Senior Credit Facilities (Details)

v3.8.0.1
Long-term Debt - Senior Credit Facilities (Details) - USD ($)
12 Months Ended
Dec. 01, 2014
Dec. 31, 2015
Dec. 31, 2017
Dec. 31, 2016
Debt Instrument [Line Items]        
Original issue discount     $ 18,390,000 $ 28,497,000
Senior Secured Credit Facilities        
Debt Instrument [Line Items]        
Maximum borrowing capacity $ 555,000,000      
Effective interest rate   4.75%    
Line of Credit | Senior Secured Credit Facilities | Federal Fund Rate        
Debt Instrument [Line Items]        
Variable rate on spread 0.50%      
Line of Credit | Senior Secured Credit Facilities | LIBOR        
Debt Instrument [Line Items]        
Variable rate on spread 1.00%      
Term Loan | Senior Secured Credit Facilities        
Debt Instrument [Line Items]        
Maximum borrowing capacity $ 500,000,000      
Line of credit outstanding $ 500,000,000      
Debt instrument issued, percentage of principal 99.50%      
Original issue discount $ 2,500,000      
Revolving Credit Facility | Line of Credit | Senior Secured Credit Facilities        
Debt Instrument [Line Items]        
Maximum borrowing capacity $ 55,000,000      
Line of credit outstanding   $ 0    
Proceeds from lines of credit   12,000,000    
Repayments of lines of credit   12,000,000    
Revolving Credit Facility | Letter of Credit | Senior Secured Credit Facilities        
Debt Instrument [Line Items]        
Remaining borrowing capacity   $ 25,000,000