Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt - Schedule of Long-Term Debt (Detail)

v3.10.0.1
Long-Term Debt - Schedule of Long-Term Debt (Detail) - USD ($)
$ in Millions
Sep. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Feb. 28, 2014
Debt Instrument [Line Items]        
Other $ 3.7   $ 7.9  
Total 2,446.6   2,268.1  
Less: current portion 672.2   102.4  
Long-term portion 1,774.4   2,165.7  
2.00% Convertible Senior Notes Due 2019 [Member]        
Debt Instrument [Line Items]        
Convertible senior notes, carrying value of liability component 649.1   1,070.0  
Total       $ 930.9
2.625% Convertible Senior Notes Due 2024 [Member]        
Debt Instrument [Line Items]        
Convertible senior notes, carrying value of liability component 410.9      
Total   $ 410.1    
7.250% Senior Notes Due 2026 [Member]        
Debt Instrument [Line Items]        
Senior notes, carrying value 394.6      
2017 Senior Secured Credit Facility [Member]        
Debt Instrument [Line Items]        
Borrowings under senior secured credit facility, carrying value     $ 1,190.2  
2018 Senior Secured Credit Facility [Member]        
Debt Instrument [Line Items]        
Borrowings under senior secured credit facility, carrying value $ 988.3