RESTRUCTURING CHARGE (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended						9 Months Ended		35 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 09, 2010 T
Restructuring Cost and Reserve [Line Items]
Previous mercury cell capacity tonnage at Charleston, TN facility (in tons)												260,000
Membrane capacity tonnage capability at Charleston, TN facility (in tons)												200,000
Percentage reduction of electricity usage per ECU produced (in hundredths)	25.00%						25.00%		25.00%
Product Segment Production Capacity Decrease												160,000
Estimated five-year project cost for Winchester relocation	$ 110						$ 110		$ 110
Estimated capital spending for Winchester relocation	80						80		80
Percentage of capital spending offset provided by State of Mississippi tax incentives (in hundredths)	40.00%						40.00%		40.00%
Restructuring charges	1.6	0.2	2.3	2.3	1.8	1.9	4.1	6.0	57.5
Inception to date Amounts Utilized (cash)									18.4
Inception to date Amounts Utilized (non-cash)									28.3
Accrued restructuring costs	10.8			13.6			10.8	13.6	10.8	13.9	12.1
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Forecast annual reduction of Winchester's annual operating costs							35
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Forecast annual reduction of Winchester's annual operating costs							40
Chlor Alkali Products Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1.3			0.5			2.7	1.0	35.8
Restructuring And Related Cost Expected Cost							3
Winchester Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.3			1.8			1.4	5.0	21.7
Restructuring And Related Cost Expected Cost							$ 6