XML 75 R58.htm IDEA: XBRL DOCUMENT v3.8.0.1
Senior Unsecured Notes - Additional Information (Detail) - USD ($)
12 Months Ended
Nov. 22, 2017
Sep. 25, 2017
Aug. 24, 2017
Dec. 31, 2017
Dec. 31, 2016
Debt Instrument [Line Items]          
Estimated offering expenses       $ 3,772,000 $ 1,964,000
Add-on Notes [Member]          
Debt Instrument [Line Items]          
Aggregate principal amount $ 200,000,000        
Senior unsecured notes, interest rate 5.625%        
Senior unsecured notes, maturity year 2025        
Net proceeds from sale of notes $ 209,200        
Price percentage for Add-on Notes, Principal amount 104.25%        
5.6250% Senior Notes [Member]          
Debt Instrument [Line Items]          
Aggregate principal amount     $ 750,000,000    
Senior unsecured notes, interest rate     5.625%    
Senior unsecured notes, maturity year     2025    
Estimated offering expenses     $ 10,300,000    
Net proceeds from sale of notes     $ 739,700,000    
Redemption price percentage as equal to principal amount of old notes to be redeemed       101.00%  
Principal payments due until maturity       $ 0  
Maturity date of notes       Sep. 01, 2025  
5.6250% Senior Notes [Member] | Maximum [Member]          
Debt Instrument [Line Items]          
Percentage of principal amount of new notes to be redeemed       40.00%  
7% Senior Notes [Member]          
Debt Instrument [Line Items]          
Senior unsecured notes, interest rate     7.00%    
Senior unsecured notes, maturity year     2022    
Repurchase of notes     $ 329,700,000    
Early tender deadline amount received on debt instrument     1,038.90    
Principal amount of old notes     $ 1,000    
Remaining principal amount outstanding of old notes redeemed   $ 300,300,000      
Redemption price percentage as equal to principal amount of old notes to be redeemed   103.50%