Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt - Additional Information (Detail)

v3.5.0.2
Long-Term Debt - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended
Sep. 30, 2015
May 04, 2015
Feb. 28, 2014
Jul. 31, 2012
Mar. 31, 2011
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Sep. 30, 2015
Mar. 31, 2014
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Jul. 26, 2012
Mar. 09, 2011
Debt Instrument [Line Items]                              
Deferred financing costs   $ 6,200,000                          
Allowable annual dividend payment or repurchase of common stock under credit facility                     $ 233,000,000        
Credit facility terms description                     The Credit Facility restricts the Company’s ability to pay dividends or repurchase its common shares to a maximum of $233.0 million until maturity and for every one dollar of share repurchase or dividend paid, the revolving credit facility’s borrowing capacity is permanently decreased by two dollars.        
Borrowings under the senior secured credit facility           $ 410,000,000         $ 410,000,000   $ 639,500,000    
Paid-in-capital in excess of par value           462,600,000         462,600,000   438,200,000    
Long-term debt           1,442,900,000         1,442,900,000   1,622,000,000    
Convertible senior notes, carrying value of liability Component           1,014,000,000         1,014,000,000   982,500,000    
Interest expense           24,000,000     $ 25,500,000   74,600,000 $ 73,700,000      
Letters of credit issued but undrawn           39,700,000         39,700,000        
Prepaid forward share repurchase transactions [Member]                              
Debt Instrument [Line Items]                              
Paid-in-capital in excess of par value                   $ 31,900,000          
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                        
Term Loan [Member]                              
Debt Instrument [Line Items]                              
Credit facility, amount repaid               $ 229,700,000              
Convertible Debt [Member]                              
Debt Instrument [Line Items]                              
Deferred financing costs                   26,600,000          
Total principal amount of convertible notes     1,150,000,000     $ 1,150,000,000         $ 1,150,000,000   1,150,000,000    
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)                     20 days        
Convertible notes, number of trading days of threshold limit in consecutive days                     30 days        
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 $ 86.28         $ 86.28     $ 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           $ 136,000,000         $ 136,000,000   167,600,000    
Convertible senior notes, carrying value of liability Component           1,014,000,000         1,014,000,000   982,500,000    
Fair value of liability to convertible notes           950,800,000         950,800,000   $ 795,900,000    
Interest expense           16,400,000     $ 16,000,000   48,700,000 $ 46,800,000      
Non-cash interest expense           9,700,000     9,300,000   28,700,000 27,000,000      
Amortization of deferred financing costs           $ 900,000     $ 900,000   2,800,000 $ 2,800,000      
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     $ 86.28                        
Senior secured revolving credit facility [Member]                              
Debt Instrument [Line Items]                              
Amount required to maintain on consolidated cash and cash equivalents                     $ 200,000,000        
Senior Secured Credit Facility [Member]                              
Debt Instrument [Line Items]                              
Credit facility borrowings used to repay outstanding borrowings         $ 196,000,000                    
Deferred financing costs     $ 2,300,000   $ 5,700,000                    
Applicable margin payable, percentage     0.50%                        
Consolidated leverage ratio                     2.50 to 1.00        
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 Credit Facility increased by 2.00% such that borrowings under the Credit Facility now bear 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%        
Long-term debt, weighted average interest rate           4.13%         4.13%   2.78%    
Credit facility, amount repaid           $ 0 $ 0                
Borrowings under the senior secured credit facility                         $ 639,700,000    
Foreign currency borrowings, outstanding           0         $ 0   0    
Aggregate annual maturity of credit facility, 2017           410,000,000         410,000,000        
Aggregate annual maturity of credit facility, 2019           1,150,000,000         $ 1,150,000,000        
Senior Secured Credit Facility [Member] | Minimum [Member]                              
Debt Instrument [Line Items]                              
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage                     0.40%        
Senior Secured Credit Facility [Member] | Maximum [Member]                              
Debt Instrument [Line Items]                              
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage                     0.50%        
Senior Secured Credit Facility [Member] | Base Rate [Member]                              
Debt Instrument [Line Items]                              
Variable rate basis                     Facility increased by 2.00% such that borrowings under the Credit Facility now bear 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%        
Senior Secured Credit Facility [Member] | Until March 9, 2016 [Member]                              
Debt Instrument [Line Items]                              
Interest rate spread on variable rate increase by percentage   0.50%                          
Senior Secured Credit Facility [Member] | After March 9, 2016 [Member]                              
Debt Instrument [Line Items]                              
Interest rate increased by percentage   2.00%                          
Senior Secured Credit Facility [Member] | After March 9, 2016 [Member] | LIBOR [Member] | Minimum [Member]                              
Debt Instrument [Line Items]                              
Interest rate spread on variable rate   4.00%                          
Senior Secured Credit Facility [Member] | After March 9, 2016 [Member] | LIBOR [Member] | Maximum [Member]                              
Debt Instrument [Line Items]                              
Interest rate spread on variable rate   5.00%                          
Senior Secured Credit Facility [Member] | After March 9, 2016 [Member] | Base Rate [Member] | Minimum [Member]                              
Debt Instrument [Line Items]                              
Interest rate spread on variable rate   3.00%                          
Senior Secured Credit Facility [Member] | After March 9, 2016 [Member] | Base Rate [Member] | Maximum [Member]                              
Debt Instrument [Line Items]                              
Interest rate spread on variable rate   4.00%                          
Senior Secured Credit Facility [Member] | Term Loan [Member]                              
Debt Instrument [Line Items]                              
Credit facility, maximum amount                           $ 500,000,000  
Credit facility borrowings used to repay outstanding borrowings       $ 500,000,000                      
Deferred financing costs       $ 4,500,000                      
Credit facility prepayments   $ 20,300,000                          
Borrowings under the senior secured credit facility                         229,700,000    
Senior Secured Credit Facility [Member] | Convertible Debt [Member]                              
Debt Instrument [Line Items]                              
Total principal amount of convertible notes     $ 1,150,000,000                        
Senior Secured Credit Facility [Member] | Senior secured revolving credit facility [Member]                              
Debt Instrument [Line Items]                              
Credit facility, maximum amount           425,000,000         $ 425,000,000       $ 700,000,000
Line of credit facility extended maturity period                     1 year        
Credit facility prepayments   $ 50,900,000                          
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         $ 410,000,000   $ 410,000,000    
Senior Secured Credit Facility [Member] | Senior secured revolving credit facility [Member] | LIBOR [Member]                              
Debt Instrument [Line Items]                              
Credit facility LIBOR minimum floor rate interest   0.25%                          
Senior Secured Credit Facility [Member] | Senior secured revolving credit facility [Member] | Base Rate [Member]                              
Debt Instrument [Line Items]                              
Variable rate basis                     The base rate under the Credit Facility represents the highest of the Federal Funds Rate plus 0.50%, the one-month LIBOR plus 1.00%, and the prime rate offered by Bank of America.        
Base rate in excess of Federal Funds Rate                     0.50%        
Base rate in excess of one-month LIBOR                     1.00%