RESTRUCTURING CHARGES (Details Textuals) $ in Millions		3 Months Ended		16 Months Ended	65 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Mar. 21, 2016 T	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 12, 2014 T	Dec. 31, 2011 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 92.8	$ 1.2		$ 129.5
Inception to date Amounts Utilized (cash)					23.8
Inception to date Amounts Utilized (non-cash)					84.6
Accrued restructuring costs	$ 20.5	20.5	12.9	$ 20.5	20.5		$ 6.7	$ 15.7
Chlor Alkali Products and Vinyls Capacity Reductions
Restructuring Cost and Reserve [Line Items]
Total Product Segment Production Capacity Decrease | T						433,000
Henderson Product Segment Production Capacity Decrease | T						153,000
Niagara Product Segment Production Capacity | T						300,000
Reduced Niagara Segment Production Capacity | T						240,000
Freeport Product Segment Production Capacity Decrease | T						220,000
Restructuring charges	92.2
Additional restructuring and related expected cost	45.0	45.0		45.0	45.0
Chlor Alkali Products Becancour
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.3	1.2	12.3
Additional restructuring and related expected cost	4.0	4.0		4.0	4.0
Tonnage reduction in chlor alkali manufacutring capactiy (in tons) | T									185,000
Winchester Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.3	$ 0.1		25.0
Additional restructuring and related expected cost	0.7	0.7		0.7	0.7
Estimated Project Cost For Plant Relocation	110.0	110.0		110.0	110.0
Estimated Capital Spending For Facility Relocation	$ 80.0	80.0		$ 80.0	$ 80.0
Government Grants for Facility Relocation Capital Spending										$ 31.0
Winchester Segment | Minimum
Restructuring Cost and Reserve [Line Items]
Forecast to reduce Winchester's annual operating costs		35.0
Winchester Segment | Maximum
Restructuring Cost and Reserve [Line Items]
Forecast to reduce Winchester's annual operating costs		$ 40.0