v3.5.0.2
Goodwill and Other Intangible Assets - Detail of the Definite-Lived Intangible Assets by Reportable Segment (Detail) - USD ($)
$ in Millions
6 Months Ended 12 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Goodwill [Line Items]    
Gross carrying amounts $ 1,250.6 $ 1,250.6
Accumulated impairment charges (2.9) (2.9)
Accumulated amortization (249.2) (215.2)
Foreign currency translation adjustment (20.1) (24.7)
Net carrying amounts 978.4 1,007.8
Chlorovinyls [Member]    
Goodwill [Line Items]    
Gross carrying amounts 1,205.8 1,205.8
Accumulated impairment charges (2.9) (2.9)
Accumulated amortization (224.6) (192.2)
Foreign currency translation adjustment (20.1) (24.6)
Net carrying amounts 958.2 986.1
Building Products [Member]    
Goodwill [Line Items]    
Gross carrying amounts 44.8 44.8
Accumulated amortization (24.6) (23.0)
Foreign currency translation adjustment   (0.1)
Net carrying amounts 20.2 21.7
Customer Relationships [Member]    
Goodwill [Line Items]    
Gross carrying amounts 1,169.7 1,169.7
Accumulated impairment charges (2.9) (2.9)
Accumulated amortization (223.5) (191.8)
Foreign currency translation adjustment (20.1) (24.7)
Net carrying amounts 923.2 950.3
Customer Relationships [Member] | Chlorovinyls [Member]    
Goodwill [Line Items]    
Gross carrying amounts 1,142.3 1,142.3
Accumulated impairment charges (2.9) (2.9)
Accumulated amortization (213.8) (182.9)
Foreign currency translation adjustment (20.1) (24.6)
Net carrying amounts 905.5 931.9
Customer Relationships [Member] | Building Products [Member]    
Goodwill [Line Items]    
Gross carrying amounts 27.4 27.4
Accumulated amortization (9.7) (8.9)
Foreign currency translation adjustment   (0.1)
Net carrying amounts 17.7 18.4
Supply Contracts [Member]    
Goodwill [Line Items]    
Gross carrying amounts 42.6 42.6
Accumulated amortization (7.3) (6.3)
Net carrying amounts 35.3 36.3
Supply Contracts [Member] | Chlorovinyls [Member]    
Goodwill [Line Items]    
Gross carrying amounts 42.6 42.6
Accumulated amortization (7.3) (6.3)
Net carrying amounts 35.3 36.3
Technology [Member]    
Goodwill [Line Items]    
Gross carrying amounts 32.3 32.3
Accumulated amortization (17.2) (16.1)
Net carrying amounts 15.1 16.2
Technology [Member] | Chlorovinyls [Member]    
Goodwill [Line Items]    
Gross carrying amounts 14.9 14.9
Accumulated amortization (2.3) (2.0)
Net carrying amounts 12.6 12.9
Technology [Member] | Building Products [Member]    
Goodwill [Line Items]    
Gross carrying amounts 17.4 17.4
Accumulated amortization (14.9) (14.1)
Net carrying amounts 2.5 3.3
Trade Names [Member]    
Goodwill [Line Items]    
Gross carrying amounts 6.0 6.0
Accumulated amortization (1.2) (1.0)
Net carrying amounts 4.8 5.0
Trade Names [Member] | Chlorovinyls [Member]    
Goodwill [Line Items]    
Gross carrying amounts 6.0 6.0
Accumulated amortization (1.2) (1.0)
Net carrying amounts $ 4.8 $ 5.0