RESTRUCTURING CHARGE (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended		20 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2010	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
Estimated capital cost converting Charleston, TN facility	$ 160				$ 160		$ 160
Tonnage reduction in chlor alkali manufacturing capacity (in tons)										100,000
Percentage reduction of electricity usage per ECU produced (in hundredths)	25.00%				25.00%		25.00%
Forecast annual reduction of Winchester's annual operating costs					30
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	1.8	1.9	2.4	0.1	3.7	2.5	48.6
Inception to date Amounts Utilized (cash)							7.6
Inception to date Amounts Utilized (non-cash)							28.3
Accrued restructuring costs	12.7		7.7		12.7	7.7	12.7	12.1	7.0
Chlor Alkali Products Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.2		0.2		0.5	0.3	31.3
Restructuring And Related Cost Expected Cost					8
Winchester Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1.6		2.2		3.2	2.2	17.3
Restructuring And Related Cost Expected Cost					$ 13