Annual report pursuant to Section 13 and 15(d)

Long-Term Debt - Additional Information (Detail)

v3.8.0.1
Long-Term Debt - Additional Information (Detail)
1 Months Ended 3 Months Ended 12 Months Ended
Jun. 30, 2017
USD ($)
Sep. 30, 2015
USD ($)
May 04, 2015
USD ($)
Feb. 15, 2017
USD ($)
Feb. 28, 2014
USD ($)
$ / shares
Mar. 31, 2014
USD ($)
Dec. 31, 2017
USD ($)
Day
$ / shares
Dec. 31, 2016
USD ($)
$ / shares
Dec. 31, 2015
USD ($)
$ / shares
Jul. 26, 2012
USD ($)
Mar. 09, 2011
USD ($)
Debt Instrument [Line Items]                      
Deferred financing costs     $ 6,200,000                
Outstanding principal amount             $ 2,384,700,000        
Credit facility, amount repaid             483,100,000        
Interest expense             160,800,000 $ 99,300,000 $ 100,500,000    
Amortization of deferred financing costs             8,400,000 7,900,000 8,500,000    
Paid-in-capital in excess of par value             407,300,000 467,600,000      
Long-term debt             2,268,100,000 1,447,900,000      
Convertible senior notes, carrying value of liability component             1,070,000,000 1,024,800,000      
Letters of credit issued but undrawn             40,800,000        
Prepaid forward share repurchase transactions [Member]                      
Debt Instrument [Line Items]                      
Forward share repurchase transactions amount         $ 685,800,000 $ 685,800,000          
Capped call transactions [Member]                      
Debt Instrument [Line Items]                      
Capped call transactions with financial institutions         123,800,000            
Senior secured prior revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Repayment of prior senior secured credit facility       $ 410,000,000              
Credit facility, amount repaid             $ 410,000,000 429,700,000      
Credit facility, amount borrowed               $ 200,000,000      
Prior Senior Secured Credit Facility [Member]                      
Debt Instrument [Line Items]                      
Credit facility amendment date             May 04, 2015        
Credit facility interest rate description             After March 9, 2016, the applicable interest rates on the Company’s borrowings under the Prior Credit Facility increased by 2.00% such that borrowings under the Prior Credit Facility began bearing interest at either LIBOR plus the applicable margin between 4.00% and 5.00% or the base rate plus the applicable margin between 3.00% and 4.00%        
Amount required to maintain on consolidated cash and cash equivalents             $ 200,000,000        
Long-term debt, weighted average interest rate               4.29%      
Senior secured revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Borrowings under the senior secured credit facility             0        
Term Loan [Member]                      
Debt Instrument [Line Items]                      
Credit facility prepayments             0        
Quarterly periodic payment, Principal $ 24,400,000                    
Interest expense             82,200,000        
Non-cash interest expense             4,200,000        
Amortization of deferred financing costs             2,800,000        
Term Loan [Member] | Level 2 [Member]                      
Debt Instrument [Line Items]                      
Outstanding principal amount             1,190,200,000        
Debt instrument, fair value             1,226,100,000        
Convertible Debt [Member]                      
Debt Instrument [Line Items]                      
Deferred financing costs           26,600,000          
Outstanding principal amount         1,150,000,000   1,150,000,000 $ 1,150,000,000      
Interest expense             68,200,000 65,300,000 61,700,000    
Non-cash interest expense             41,200,000 38,600,000 35,700,000    
Amortization of deferred financing costs             $ 4,000,000 $ 3,800,000 $ 3,200,000    
Aggregate principal amount of convertible senior notes issued         1,000,000,000            
Additional principal amount of convertible notes         $ 150,000,000            
Convertible notes, interest rate         2.00%            
Convertible notes maturity         Aug. 15, 2019            
Convertible notes, conversion feature             Holders of the Convertible Notes may convert their notes at their option under the following circumstances: (i) during any calendar quarter commencing after the calendar quarter ending March 31, 2014, if the last reported sale price of the Company’s common shares for at least 20 trading days (whether or not consecutive) in a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter exceeds 130% of the conversion price for the Convertible Notes on each applicable trading day; (ii) during the five business-day period immediately after any five consecutive trading day period, or the measurement period, in which the trading price per $1,000 principal amount of Convertible Notes for each trading day of that measurement period was less than 98% of the product of the last reported sale price of the Company’s common shares and the conversion rate for the Convertible Notes for each such day; or (iii) upon the occurrence of specified corporate events. On and after May 15, 2019, holders may convert their Convertible Notes at any time, regardless of the foregoing circumstances.        
Convertible notes, number of trading days of threshold limit (whether or not consecutive) | Day             20        
Convertible notes, number of trading days of threshold limit in consecutive days | Day             30        
Minimum percentage of common share price over conversion price for conversion         130.00%            
Principal amount of convertible notes         $ 1,000            
Minimum percentage of the product of common share price and conversion rate for convertible notes         98.00%            
Convertible notes initial conversion rate         11.5908            
Convertible notes initial conversion price | $ / shares             $ 86.28 $ 86.28 $ 86.28    
Paid-in-capital in excess of par value         $ 219,100,000 5,100,000          
Proceeds received from the issuance of the Convertible notes         1,150,000,000            
Long-term debt         $ 930,900,000            
Effective interest rate on convertible notes         6.20%            
Unamortized debt discount and debt issuance costs             $ 80,000,000 $ 125,200,000      
Convertible senior notes, carrying value of liability component             1,070,000,000 1,024,800,000      
Fair value of liability to convertible notes             $ 1,066,000,000 961,300,000      
Convertible Debt [Member] | Debt Issuance Costs [Member]                      
Debt Instrument [Line Items]                      
Deferred financing costs           $ 21,500,000          
Convertible Debt [Member] | Capped call transactions [Member]                      
Debt Instrument [Line Items]                      
Convertible notes initial conversion price | $ / shares         $ 86.28            
Base Rate [Member] | Senior secured prior revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Variable rate basis             Facility increased by 2.00% such that borrowings under the Prior Credit Facility began bearing interest at either LIBOR plus the applicable margin between 4.00% and 5.00% or the base rate plus the applicable margin between 3.00% and 4.00%        
Base rate interest rate floor       1.75%              
Senior Secured Credit Facility [Member]                      
Debt Instrument [Line Items]                      
Credit facility, maximum amount       $ 1,450,000,000              
Deferred financing costs       $ 22,600,000              
Senior secured credit facility, discount percentage       2.00%              
Senior secured credit facility, discount amount       $ 26,000,000              
Line of credit facility, frequency of interest payments       quarterly              
Long-term debt, weighted average interest rate             6.79%        
Senior Secured Credit Facility [Member] | Senior secured prior revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Line of credit facility extended maturity period             1 year        
Credit facility prepayments     50,900,000                
Credit facility, maximum amount             $ 425,000,000       $ 700,000,000
Amended maturity date of credit facility             Mar. 09, 2017        
Decreased amount in credit facility borrowing capacity   $ (39,100,000) (235,900,000)                
Borrowings under the senior secured credit facility               410,000,000      
Foreign currency borrowings, outstanding             $ 0 $ 0      
Senior Secured Credit Facility [Member] | Senior secured revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Credit facility, maximum amount       $ 150,000,000              
Credit facility, maturity date             Feb. 15, 2022        
Credit facility LIBOR minimum floor rate interest       0.75%              
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage       0.50%              
Senior Secured Credit Facility [Member] | Senior secured revolving credit facility [Member] | Convertible Notes Exceeds 250 Million [Member]                      
Debt Instrument [Line Items]                      
Credit facility, maturity date             Feb. 14, 2019        
Senior Secured Credit Facility [Member] | Minimum [Member] | Convertible Notes Exceeds 250 Million [Member]                      
Debt Instrument [Line Items]                      
Outstanding principal amount       $ 250,000,000              
Senior Secured Credit Facility [Member] | Prior Term Loan [Member]                      
Debt Instrument [Line Items]                      
Credit facility prepayments     $ 20,300,000                
Credit facility, maximum amount                   $ 500,000,000  
Senior Secured Credit Facility [Member] | Term Loan [Member]                      
Debt Instrument [Line Items]                      
Outstanding principal amount       $ 1,300,000,000              
Credit facility, maturity date             Feb. 15, 2023        
Borrowings under the senior secured credit facility             $ 1,226,900,000        
Senior Secured Credit Facility [Member] | Term Loan [Member] | Convertible Notes Exceeds 250 Million [Member]                      
Debt Instrument [Line Items]                      
Credit facility, maturity date             May 16, 2019        
Senior Secured Credit Facility [Member] | LIBOR [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       1.00%              
Senior Secured Credit Facility [Member] | LIBOR [Member] | Senior secured prior revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Credit facility LIBOR minimum floor rate interest     0.25%                
Senior Secured Credit Facility [Member] | Base Rate [Member] | Term Loan [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       4.50%              
Senior Secured Credit Facility [Member] | Eurodollar [Member] | Term Loan [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       5.50%              
Senior Secured Credit Facility [Member] | Federal Funds Rate [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       0.50%              
Senior secured revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Borrowings under the senior secured credit facility             $ 0        
Until March 9, 2016 [Member] | Senior Secured Credit Facility [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate increase by percentage     0.50%                
After March 9, 2016 [Member] | Senior Secured Credit Facility [Member]                      
Debt Instrument [Line Items]                      
Interest rate increased by percentage     2.00%                
After March 9, 2016 [Member] | Senior Secured Credit Facility [Member] | LIBOR [Member] | Minimum [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate     4.00%                
After March 9, 2016 [Member] | Senior Secured Credit Facility [Member] | LIBOR [Member] | Maximum [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate     5.00%                
After March 9, 2016 [Member] | Senior Secured Credit Facility [Member] | Base Rate [Member] | Minimum [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate     3.00%                
After March 9, 2016 [Member] | Senior Secured Credit Facility [Member] | Base Rate [Member] | Maximum [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate     4.00%                
Until August 15, 2017 [Member] | Senior Secured Credit Facility [Member] | Base Rate [Member] | Senior secured revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       3.75%              
Until August 15, 2017 [Member] | Senior Secured Credit Facility [Member] | Eurodollar [Member] | Senior secured revolving credit facility [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       4.75%              
Scenario Leverage Ratio One [Member] | Senior Secured Credit Facility [Member] | Base Rate [Member] | Senior secured revolving credit facility [Member] | After August 15, 2017 [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       3.50%              
Scenario Leverage Ratio One [Member] | Senior Secured Credit Facility [Member] | Eurodollar [Member] | Senior secured revolving credit facility [Member] | After August 15, 2017 [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       4.50%              
Scenario Leverage Ratio Two [Member] | Senior Secured Credit Facility [Member] | Base Rate [Member] | Senior secured revolving credit facility [Member] | After August 15, 2017 [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       3.75%              
Scenario Leverage Ratio Two [Member] | Senior Secured Credit Facility [Member] | Eurodollar [Member] | Senior secured revolving credit facility [Member] | After August 15, 2017 [Member]                      
Debt Instrument [Line Items]                      
Interest rate spread on variable rate       4.75%