SEGMENT INFORMATION (Details) - USD ($) $ in Millions	3 Months Ended	77 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017
Segment Reporting Information [Line Items]
Sales	$ 1,567.1	$ 1,348.2
Income before taxes [Abstract]
Income (loss) before taxes	17.9	(55.4)
Restructuring charges	(8.2)	(92.8)	$ (157.8)
Acquisition-related costs	7.0	10.2
Other operating (expense) income	(0.4)	10.9
Interest expense	(52.4)	(48.5)
Interest income	0.2	0.3
Chlor Alkali Products and Vinyls Segment
Segment Reporting Information [Line Items]
Sales	836.9	704.3
Income before taxes [Abstract]
Income (loss) before taxes	87.5	68.1
Epoxy Segment
Segment Reporting Information [Line Items]
Sales	567.6	460.2
Income before taxes [Abstract]
Income (loss) before taxes	(1.2)	8.2
Winchester Segment
Segment Reporting Information [Line Items]
Sales	162.6	183.7
Income before taxes [Abstract]
Income (loss) before taxes	25.1	28.7
Restructuring charges		(0.3)	$ (25.5)
Corporate/Other
Income before taxes [Abstract]
Pension income	10.3	12.2
Environmental expense	(2.6)	(2.7)
Other corporate and unallocated costs	(33.4)	(29.6)
Restructuring charges	(8.2)	(92.8)
Acquisition-related costs	$ 7.0	$ 10.2

Other corporate and unallocated costs recognized by the entity in the period.

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All components of pension costs, excluding service cost and the amortization of prior service costs, such as expected return on plan assets, interest cost and recognized actuarial gains and losses.

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Costs recognized in the income statement in the period for known or estimated future costs arising from requirements to perform activities to remediate one or more sites.

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

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The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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