GOODWILL AND INTANGIBLES (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 2,118.0	$ 2,174.1	$ 747.1
Acquisition activity		1,427.5
Goodwill, Purchase Accounting Adjustments	(55.0)
Foreign currency translation adjustment	(1.1)	(0.5)
Chlor Alkali Products and Vinyls Segment
Goodwill [Line Items]
Goodwill	1,831.3	1,877.5	747.1
Acquisition activity		1,130.8
Goodwill, Purchase Accounting Adjustments	(45.3)
Foreign currency translation adjustment	(0.9)	(0.4)
Epoxy Segment
Goodwill [Line Items]
Goodwill	286.7	296.6	$ 0.0
Acquisition activity		296.7
Goodwill, Purchase Accounting Adjustments	(9.7)
Foreign currency translation adjustment	$ (0.2)	$ (0.1)