v3.5.0.2
Goodwill and Other Intangible Assets - Detail of the Changes Made to Goodwill (Detail) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Goodwill [Line Items]    
Gross goodwill at the beginning of the period $ 1,926.2  
Goodwill write-downs from sales of assets (3.3)  
Cumulative foreign currency translation adjustments 7.6  
Gross goodwill at the end of the period 1,930.5  
Accumulated impairment losses (1,074.1) $ (1,074.1)
Net goodwill at the end of the period 856.4 852.1
Chlorovinyls [Member]    
Goodwill [Line Items]    
Gross goodwill at the beginning of the period 1,766.0  
Goodwill write-downs from sales of assets (3.3)  
Cumulative foreign currency translation adjustments 7.6  
Gross goodwill at the end of the period 1,770.3  
Accumulated impairment losses (923.7) (923.7)
Net goodwill at the end of the period 846.6 842.3
Building Products [Member]    
Goodwill [Line Items]    
Gross goodwill at the beginning of the period 160.2  
Gross goodwill at the end of the period 160.2  
Accumulated impairment losses (150.4) (150.4)
Net goodwill at the end of the period $ 9.8 $ 9.8