Olin (OLN) 10-K 25 Feb 19 2018 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2019	Jun. 30, 2018
Document Information [Line Items]
Entity Registrant Name	Olin Corporation
Entity Central Index Key	74,303
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		164,877,488
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 4,774,200,502

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 178.8	$ 218.4	$ 184.5	$ 392
Receivables, net	776.3	733.2
Income taxes receivable	5.9	16.9
Inventories, net	711.4	682.6
Other current assets	35	48.1
Total current assets	1,707.4	1,699.2
Property, plant and equipment, net	3,482.1	3,575.8
Deferred income taxes	26.3	36.4
Other assets	1,150.4	1,208.4
Intangible assets, net	511.6	578.5
Goodwill	2,119.6	2,120	2,118
Total assets	8,997.4	9,218.3
Current liabilities:
Current installments of long-term debt	125.9	0.7
Accounts payable	636.5	669.8
Income taxes payable	22.6	9.4
Accrued liabilities	333.3	274.4
Total current liabilities	1,118.3	954.3
Long-term debt	3,104.4	3,611.3
Accrued pension liability	674.3	635.9
Deferred income taxes	518.9	511.2
Other liabilities	749.3	751.9
Total liabilities	6,165.2	6,464.6
Commitments and contingencies
Shareholders' equity:
Commons stock, par value $1 per share: Authorized, 240.0 shares; Issued and outstanding, 165.3 shares (167.1 in 2017)	165.3	167.1
Additional paid-in capital	2,247.4	2,280.9
Accumulated other comprehensive loss	(651)	(484.6)	(510)	(492.5)
Retained earnings	1,070.5	790.3
Total shareholders' equity	2,832.2	2,753.7	$ 2,273	$ 2,418.8
Total liabilities and shareholders' equity	$ 8,997.4	$ 9,218.3

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Millions	Dec. 31, 2018	Dec. 31, 2017
Shareholders' Equity:
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, authorized (in shares)	240	240
Common stock, issued (in shares)	165.3	167.1
Common stock, outstanding (in shares)	165.3	167.1

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended			98 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Income Statement [Abstract]
Sales	$ 1,635	$ 1,872.4	$ 1,728.4	$ 1,710.3	$ 1,619.9	$ 1,554.9	$ 1,526.5	$ 1,567.1	$ 6,946.1	$ 6,268.4	$ 5,550.6
Operating expenses:
Cost of goods sold	1,391	1,441.7	1,460.7	1,528.7	1,400.2	1,349.3	1,407.9	1,397.5	5,822.1	5,554.9	4,944.5
Selling and administration									430.6	369.8	347.2
Restructuring charges									21.9	37.6	112.9	$ 209.1
Acquisition-related costs									1	12.8	48.8
Other operating income									6.4	3.3	10.6
Operating income									676.9	296.6	107.8
Earnings (losses) of non-consolidated affiliates									(19.7)	1.8	1.7
Interest expense									243.2	217.4	191.9
Interest income									1.6	1.8	3.4
Non-operating pension income									21.7	34.4	44.8
Income (loss) before taxes									437.3	117.2	(34.2)
Income tax provision (benefit)									109.4	(432.3)	(30.3)
Net income (loss)	$ 53.3	$ 195.1	$ 58.6	$ 20.9	$ 489.3	$ 52.7	$ (5.9)	$ 13.4	$ 327.9	$ 549.5	$ (3.9)
Net income (loss) per common share:
Basic	$ 0.32	$ 1.17	$ 0.35	$ 0.13	$ 2.93	$ 0.32	$ (0.04)	$ 0.08	$ 1.97	$ 3.31	$ (0.02)
Diluted	$ 0.32	$ 1.16	$ 0.35	$ 0.12	$ 2.89	$ 0.31	$ (0.04)	$ 0.08	$ 1.95	$ 3.26	$ (0.02)
Average common shares outstanding:
Basic									166.8	166.2	165.2
Diluted									168.4	168.5	165.2

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Consolidated Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 53.3	$ 195.1	$ 58.6	$ 20.9	$ 489.3	$ 52.7	$ (5.9)	$ 13.4	$ 327.9	$ 549.5	$ (3.9)
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments, net									(22.2)	31.7	(12)
Unrealized (losses) gains on derivative contracts, net									(11.7)	(1.7)	19.7
Pension and postretirement liability adjustments, net									(74.9)	(21.6)	(37.5)
Amortization of prior service costs and actuarial losses, net									28.3	17	12.3
Total other comprehensive (loss) income, net of tax									(80.5)	25.4	(17.5)
Comprehensive income (loss)									$ 247.4	$ 574.9	$ (21.4)

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Balance (in shares) at Dec. 31, 2015		165.1
Balance at Dec. 31, 2015	$ 2,418.8	$ 165.1	$ 2,236.4	$ (492.5)	$ 509.8
Net income (loss)	(3.9)	0	0	0	(3.9)
Total other comprehensive (loss) income, net of tax	(17.5)	0	0	(17.5)	0
Dividends paid:
Common stock ($0.80 per share)	$ (132.1)	$ 0	0	0	(132.1)
Common stock issued for:
Stock options exercised (in shares)	0.3	0.3
Stock options exercised	$ 4.1	$ 0.3	3.8	0	0
Other transactions (in shares)		0
Other transactions	(0.8)	$ 0	(0.8)	0	0
Stock-based compensation	4.4	$ 0	4.4	0	0
Balance (in shares) at Dec. 31, 2016		165.4
Balance at Dec. 31, 2016	2,273	$ 165.4	2,243.8	(510)	373.8
Net income (loss)	549.5	0	0	0	549.5
Total other comprehensive (loss) income, net of tax	25.4	0	0	25.4	0
Dividends paid:
Common stock ($0.80 per share)	$ (133)	$ 0	0	0	(133)
Common stock issued for:
Stock options exercised (in shares)	1.7	1.7
Stock options exercised	$ 32.4	$ 1.7	30.7	0	0
Other transactions (in shares)		0
Other transactions	(0.9)	$ 0	(0.9)	0	0
Stock-based compensation	7.3	$ 0	7.3	0	0
Balance (in shares) at Dec. 31, 2017		167.1
Balance at Dec. 31, 2017	2,753.7	$ 167.1	2,280.9	(484.6)	790.3
Income tax reclassification adjustment	0	0	0	(85.9)	85.9
Net income (loss)	327.9	0	0	0	327.9
Total other comprehensive (loss) income, net of tax	(80.5)	0	0	(80.5)	0
Dividends paid:
Common stock ($0.80 per share)	(133.6)	$ 0	0	0	(133.6)
Common stock repurchased and retired (in shares)		(2.1)
Common stock repurchased and retired	$ (50)	$ (2.1)	(47.9)	0	0
Common stock issued for:
Stock options exercised (in shares)	0.2	0.2
Stock options exercised	$ 3.4	$ 0.2	3.2	0	0
Other transactions (in shares)		0.1
Other transactions	2.1	$ 0.1	2	0	0
Stock-based compensation	9.2	$ 0	9.2	0	0
Balance (in shares) at Dec. 31, 2018		165.3
Balance at Dec. 31, 2018	$ 2,832.2	$ 165.3	$ 2,247.4	$ (651)	$ 1,070.5

CONSOLIDATED STATEMENTS OF SH_2

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Dividends paid (in dollars per share)	$ 0.80	$ 0.80	$ 0.80

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net income (loss)	$ 327.9	$ 549.5	$ (3.9)
Adjustments to reconcile net income (loss) to net cash and cash equivalents provided by (used for) operating activities:
Losses (earnings) of non-consolidated affiliates	19.7	(1.8)	(1.7)
Losses (gains) on disposition of property, plant and equipment	2	(3.1)	0.7
Stock-based compensation	12	9.1	7.5
Depreciation and amortization	601.4	558.9	533.5
Deferred income taxes	35.6	(452.7)	(32.7)
Write-off of equipment and facility included in restructuring charges	2.6	1.4	76.6
Qualified pension plan contributions	(2.6)	(1.7)	(7.3)
Qualified pension plan income	(15)	(26.9)	(37.5)
Change in assets and liabilities:
Receivables	(46.3)	(49.9)	38.5
Income taxes receivable/payable	24.5	9.6	10.7
Inventories	(35.5)	(37.8)	23.9
Other current assets	0.2	(12.1)	20.9
Accounts payable and accrued liabilities	(14.5)	100	(13.1)
Other assets	(2.6)	5.8	(4.3)
Other noncurrent liabilities	4.3	(5.9)	(12.1)
Other operating activities	(5.9)	6.4	3.5
Net operating activities	907.8	648.8	603.2
Investing Activities
Capital expenditures	(385.2)	(294.3)	(278)
Business acquired and related transactions, net of cash acquired	0	0	(69.5)
Payments under long-term supply contracts	0	(209.4)	(175.7)
Proceeds from sale/leaseback of equipment	0		40.4
Proceeds from disposition of property, plant and equipment	2.9	5.2	0.5
Proceeds from disposition of affiliated companies	0	0	8.8
Net investing activities	(382.3)	(498.5)	(473.5)
Long-term debt:
Borrowings	570	2,035.5	230
Repayments	946.1	2,037.9	435.3
Common stock repurchased and retired	(50)	0	0
Stock options exercised	3.4	29.8	0.5
Excess tax benefits from stock-based compensation	0	0	0.4
Dividends paid	(133.6)	(133)	(132.1)
Debt issuance costs	(8.5)	(11.2)	(1)
Net financing activities	(564.8)	(116.8)	(337.5)
Effect of exchange rate changes on cash and cash equivalents	(0.3)	0.4	0.3
Net (decrease) increase in cash and cash equivalents	(39.6)	33.9	(207.5)
Cash and cash equivalents, beginning of year	218.4	184.5	392
Cash and cash equivalents, end of year	178.8	218.4	184.5
Cash paid for interest and income taxes:
Interest, net	208.8	200.9	200.8
Income taxes, net of refunds	$ 52.9	$ 18	$ (2.6)

DESCRIPTION OF BUSINESS

DESCRIPTION OF BUSINESS	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS	NOTE 1 . DESCRIPTION OF BUSINESS Olin Corporation (Olin) is a Virginia corporation, incorporated in 1892, having its principal executive offices in Clayton, MO. We are a manufacturer concentrated in three business segments: Chlor Alkali Products and Vinyls, Epoxy and Winchester. The Chlor Alkali Products and Vinyls segment manufactures and sells chlorine and caustic soda, ethylene dichloride and vinyl chloride monomer, methyl chloride, methylene chloride, chloroform, carbon tetrachloride, perchloroethylene, trichloroethylene and vinylidene chloride, hydrochloric acid, hydrogen, bleach products and potassium hydroxide. The Epoxy segment produces and sells a full range of epoxy materials, including allyl chloride, epichlorohydrin, liquid epoxy resins, solid epoxy resins and downstream products such as differentiated epoxy resins and additives. The Winchester segment produces and sells sporting ammunition, reloading components, small caliber military ammunition and components, and industrial cartridges.

ACCOUNTING POLICIES

ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
ACCOUNTING POLICIES	NOTE 2 . ACCOUNTING POLICIES The preparation of the consolidated financial statements requires estimates and assumptions that affect amounts reported and disclosed in the financial statements and related notes. Actual results could differ from those estimates. Basis of Presentation The consolidated financial statements include the accounts of Olin and all majority-owned subsidiaries. Investment in our affiliates are accounted for on the equity method. Accordingly, we include only our share of earnings or losses of these affiliates in consolidated net income (loss). Certain reclassifications were made to prior year amounts to conform to the 2018 presentation. Revenue Recognition In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, “Revenue from Contracts with Customers” (ASU 2014-09), which amends Accounting Standards Codification (ASC) 605 “Revenue Recognition” and creates a new topic, ASC 606 “Revenue from Contracts with Customers” (ASC 606). Subsequent to the issuance of ASU 2014-09, ASC 606 was amended by various updates that amend and clarify the impact and implementation of the aforementioned update. We adopted these updates on January 1, 2018 using the modified retrospective transition method. The cumulative effect of applying the updates did not have a material impact on our consolidated financial statements. The most significant impact the updates had was on our accounting policies and disclosures on revenue recognition. We derive our revenues primarily from the manufacturing and delivery of goods to customers. Revenues are recognized on sales of goods at the time when control of those goods is transferred to our customers at an amount that reflects the consideration to which we expect to be entitled in exchange for those goods. We primarily sell our goods directly to customers, and to a lesser extent, through distributors. Payment terms are typically 30 to 90 days from date of invoice. Our contracts do not typically have a significant financing component. Right to payment is determined at the point in time in which control has transferred to the customer. A performance obligation is a promise in a contract to transfer a distinct good to the customer. At contract inception, we assess the goods promised in our contracts with customers and identify a performance obligation for each promise to transfer to the customer a good (or bundle of goods) that is distinct. A contract’s transaction price is based on the price stated in the contract and allocated to each distinct performance obligation and revenue is recognized when the performance obligation is satisfied. Substantially all of our contracts have a single distinct performance obligation or multiple performance obligations which are distinct and represent individual promises within the contract. Substantially all of our performance obligations are satisfied at a single point in time, when control is transferred, which is generally upon shipment or delivery as stated in the contract terms. All taxes assessed by governmental authorities that are both imposed on and concurrent with our revenue-producing transactions and collected from our customers are excluded from the measurement of the transaction price. Shipping and handling fees billed to customers are included in revenue and are considered activities to fulfill the promise to transfer the good. Allowances for estimated returns, discounts and rebates are considered variable consideration, which may be constrained, and are estimated and recognized when sales are recorded. The estimates are based on various market data, historical trends and information from customers. Actual returns, discounts and rebates have not been materially different from estimates. For all contracts that have a duration of one year or less at contract inception, we do not adjust the promised amount of consideration for the effects of a significant financing component. Substantially all of our revenue is derived from contracts with an original expected length of time of one year or less and for which we recognize revenue for the amount in which we have the right to invoice at the point in time in which control has transferred to the customer. However, a portion of our revenue is derived from long-term contracts which have contract periods that vary between one to multi-year. Certain of these contracts represent contracts with minimum purchase obligations, which can be substantially different than the actual revenue recognized. Such contracts consist of varying types of products across our chemical businesses. Certain contracts include variable volumes and/or variable pricing with pricing provisions tied to commodity, consumer price or other indices. The transaction price allocated to the remaining performance obligations related to our contracts was excluded from the disclosure of our remaining performance obligations based on the following practical expedients that we elected to apply: (i) contracts with index-based pricing or variable volume attributes in which such variable consideration is allocated entirely to a wholly unsatisfied performance obligation; and (ii) contracts with an original expected duration of one year or less. Refer to Note 21 “Segment Information” for information regarding the disaggregation of revenue by primary geographical markets and major product lines. Cost of Goods Sold and Selling and Administration Expenses Cost of goods sold includes the costs of inventory sold, related purchasing, distribution and warehousing costs, costs incurred for shipping and handling, depreciation and amortization expense related to these activities and environmental remediation costs and recoveries. Selling and administration expenses include personnel costs associated with sales, marketing and administration, research and development, legal and legal-related costs, consulting and professional services fees, advertising expenses, depreciation expense related to these activities, foreign currency translation and other similar costs. Acquisition-related Costs Acquisition-related costs include advisory, legal, accounting and other professional fees incurred in connection with the purchase and integration of our acquisitions. Acquisition-related costs also may include costs which arise as a result of acquisitions, including contractual change in control provisions, contract termination costs, compensation payments related to the acquisition or pension and other postretirement benefit plan settlements. Other Operating Income Other operating income consists of miscellaneous operating income items, which are related to our business activities, and gains (losses) on disposition of property, plant and equipment. Included in other operating income were the following: Years Ended December 31, 2018 2017 2016 ($ in millions) Gains (losses) on disposition of property, plant and equipment, net $ (2.0 ) $ 3.1 $ (0.7 ) Gains on insurance recoveries 8.0 — 11.0 Other 0.4 0.2 0.3 Other operating income $ 6.4 $ 3.3 $ 10.6 Other operating income for 2018 included an $8.0 million insurance recovery for a second quarter 2017 business interruption at our Freeport, TX vinyl chloride monomer facility partially offset by a $1.7 million loss on the sale of land. The gains on disposition of property, plant and equipment in 2017 included a gain of $3.3 million from the sale of a former manufacturing facility. The gains on insurance recoveries in 2016 included insurance recoveries for property damage and business interruption related to a 2008 Henderson, NV chlor alkali facility incident. Other Income (Expense) Other income (expense) consists of non-operating income and expense items which are not related to our primary business activities. Foreign Currency Translation Our worldwide operations utilize the U.S. dollar (USD) or local currency as the functional currency, where applicable. For foreign entities where the USD is the functional currency, gains and losses resulting from balance sheet translations are included in selling and administration. For foreign entities where the local currency is the functional currency, assets and liabilities denominated in local currencies are translated into USD at end-of-period exchange rates and the resultant translation adjustments are included in accumulated other comprehensive loss. Assets and liabilities denominated in other than the local currency are remeasured into the local currency prior to translation into USD and the resultant exchange gains or losses are included in income in the period in which they occur. Income and expenses are translated into USD using an approximation of the average rate prevailing during the period. We change the functional currency of our separate and distinct foreign entities only when significant changes in economic facts and circumstances indicate clearly that the functional currency has changed. Cash and Cash Equivalents All highly liquid investments, with a maturity of three months or less at the date of purchase, are considered to be cash equivalents. Short-Term Investments We classify our marketable securities as available-for-sale, which are reported at fair market value with unrealized gains and losses included in accumulated other comprehensive loss, net of applicable taxes. The fair value of marketable securities is determined by quoted market prices. Realized gains and losses on sales of investments, as determined on the specific identification method, and declines in value of securities judged to be other-than-temporary are included in other income (expense) in the consolidated statements of operations. Interest and dividends on all securities are included in interest income and other income (expense), respectively. As of December 31, 2018 and 2017 , we had no short-term investments recorded on our consolidated balance sheets. Allowance for Doubtful Accounts Receivable We evaluate the collectibility of accounts receivable based on a combination of factors. We estimate an allowance for doubtful accounts as a percentage of net sales based on historical bad debt experience. This estimate is periodically adjusted when we become aware of a specific customer’s inability to meet its financial obligations (e.g., bankruptcy filing) or as a result of changes in the overall aging of accounts receivable. While we have a large number of customers that operate in diverse businesses and are geographically dispersed, a general economic downturn in any of the industry segments in which we operate could result in higher than expected defaults, and, therefore, the need to revise estimates for the provision for doubtful accounts could occur. Inventories Inventories are valued at the lower of cost and net realizable value. For U.S. inventories, inventory costs are determined principally by the last-in, first-out (LIFO) method of inventory accounting while for international inventories, inventory costs are determined principally by the first-in, first-out (FIFO) method of inventory accounting. Costs for other inventories have been determined principally by the average-cost method (primarily operating supplies, spare parts and maintenance parts). Elements of costs in inventories include raw materials, direct labor and manufacturing overhead. Property, Plant and Equipment Property, plant and equipment are recorded at cost. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets. Interest costs incurred to finance expenditures for major long-term construction projects are capitalized as part of the historical cost and included in property, plant and equipment and are depreciated over the useful lives of the related assets. Leasehold improvements are amortized over the term of the lease or the estimated useful life of the improvement, whichever is shorter. Start-up costs are expensed as incurred. Expenditures for maintenance and repairs are charged to expense when incurred while the costs of significant improvements, which extend the useful life of the underlying asset, are capitalized. Property, plant and equipment are reviewed for impairment when conditions indicate that the carrying values of the assets may not be recoverable. Such impairment conditions include an extended period of idleness or a plan of disposal. If such impairment indicators are present or other factors exist that indicate that the carrying amount of an asset may not be recoverable, we determine whether impairment has occurred through the use of an undiscounted cash flow analysis at the lowest level for which identifiable cash flows exist. For our Chlor Alkali Products and Vinyls, Epoxy and Winchester segments, the lowest level for which identifiable cash flows exist is the operating facility level or an appropriate grouping of operating facilities level. The amount of impairment loss, if any, is measured by the difference between the net book value of the assets and the estimated fair value of the related assets. Asset Retirement Obligations We record the fair value of an asset retirement obligation associated with the retirement of a tangible long-lived asset as a liability in the period incurred. The liability is measured at discounted fair value and is adjusted to its present value in subsequent periods as accretion expense is recorded. The corresponding asset retirement costs are capitalized as part of the carrying amount of the related long-lived asset and depreciated over the asset’s useful life. Asset retirement obligations are reviewed annually in the fourth quarter and/or when circumstances or other events indicate that changes underlying retirement assumptions may have occurred. The activities of our asset retirement obligations were as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 54.3 $ 55.4 Accretion 3.2 3.0 Spending (8.0 ) (8.8 ) Foreign currency translation adjustments (0.2 ) 0.2 Adjustments 10.9 4.5 Ending balance $ 60.2 $ 54.3 At December 31, 2018 and 2017 , our consolidated balance sheets included an asset retirement obligation of $49.6 million and $43.8 million , respectively, which were classified as other noncurrent liabilities. In 2018, we had net adjustments that increased the asset retirement obligation by $10.9 million which was primarily related to additional asset retirement obligations for leased assets. In 2017 , we had net adjustments that increased the asset retirement obligation by $4.5 million which was primarily comprised of increases in estimated costs for certain assets. Comprehensive Income (Loss) Accumulated other comprehensive loss consists of foreign currency translation adjustments, pension and postretirement liability adjustments, pension and postretirement amortization of prior service costs and actuarial losses and net unrealized (losses) gains on derivative contracts. Goodwill Goodwill is not amortized, but is reviewed for impairment annually in the fourth quarter and/or when circumstances or other events indicate that impairment may have occurred. Accounting Standards Codification (ASC) 350 “Intangibles—Goodwill and Other” (ASC 350) permits entities to make a qualitative assessment of whether it is more likely than not that a reporting unit’s fair value is less than its carrying amount before applying the two-step goodwill impairment test. Circumstances that are considered as part of the qualitative assessment and could trigger the two-step impairment test include, but are not limited to: a significant adverse change in the business climate; a significant adverse legal judgment; adverse cash flow trends; an adverse action or assessment by a government agency; unanticipated competition; decline in our stock price; and a significant restructuring charge within a reporting unit. We define reporting units at the business segment level or one level below the business segment level. For purposes of testing goodwill for impairment, goodwill has been allocated to our reporting units to the extent it relates to each reporting unit. Based upon our qualitative assessment, it is more likely than not that the fair value of our reporting units are greater than their carrying amounts as of December 31, 2018 . No impairment charges were recorded for 2018 , 2017 or 2016 . It is our practice, at a minimum, to perform a quantitative goodwill impairment test in the fourth quarter every three years. In the fourth quarter of 2016, we performed our triennial quantitative goodwill impairment test for our reporting units. We use a discounted cash flow approach to develop the estimated fair value of a reporting unit when a quantitative test is performed. Management judgment is required in developing the assumptions for the discounted cash flow model. We also corroborate our discounted cash flow analysis by evaluating a market-based approach that considers earnings before interest, taxes, depreciation and amortization (EBITDA) multiples from a representative sample of comparable public companies. As a further indicator that each reporting unit has been valued appropriately using a discounted cash flow model, the aggregate fair value of all reporting units is reconciled to the total market value of Olin. An impairment would be recorded if the carrying amount of a reporting unit exceeded the estimated fair value. Based on the aforementioned analysis, the estimated fair value of our reporting units substantially exceeded the carrying value of the reporting units. The discount rate, profitability assumptions and terminal growth rate of our reporting units and the cyclical nature of the chlor alkali industry were the material assumptions utilized in the discounted cash flow model used to estimate the fair value of each reporting unit. The discount rate reflects a weighted-average cost of capital, which is calculated based on observable market data. Some of this data (such as the risk free or treasury rate and the pretax cost of debt) are based on the market data at a point in time. Other data (such as the equity risk premium) are based upon market data over time for a peer group of companies in the chemical manufacturing or distribution industries with a market capitalization premium added, as applicable. The discounted cash flow analysis requires estimates, assumptions and judgments about future events. Our analysis uses our internally generated long-range plan. Our discounted cash flow analysis uses the assumptions in our long-range plan about terminal growth rates, forecasted capital expenditures and changes in future working capital requirements to determine the implied fair value of each reporting unit. The long-range plan reflects management judgment, supplemented by independent chemical industry analyses which provide multi-year industry operating and pricing forecasts. We believe the assumptions used in our goodwill impairment analysis are appropriate and result in reasonable estimates of the implied fair value of each reporting unit. However, given the economic environment and the uncertainties regarding the impact on our business, there can be no assurance that our estimates and assumptions, made for purposes of our goodwill impairment testing, will prove to be an accurate prediction of the future. If our assumptions regarding future performance are not achieved, we may be required to record goodwill impairment charges in future periods. It is not possible at this time to determine if any such future impairment charge would result or, if it does, whether such charge would be material. Intangible Assets In conjunction with our acquisitions, we have obtained access to the customer contracts and relationships, trade names, acquired technology and other intellectual property of the acquired companies. These relationships are expected to provide economic benefit for future periods. Amortization expense is recognized on a straight-line basis over the estimated lives of the related assets. The amortization period of customer contracts and relationships, trade names, acquired technology and other intellectual property represents our best estimate of the expected usage or consumption of the economic benefits of the acquired assets, which is based on the company’s historical experience. Intangible assets with finite lives are reviewed for impairment when conditions indicate that the carrying values of the assets may not be recoverable. Circumstances that are considered as part of the qualitative assessment and could trigger a quantitative impairment test include, but are not limited to: a significant adverse change in the business climate; a significant adverse legal judgment including asset specific factors; adverse cash flow trends; an adverse action or assessment by a government agency; unanticipated competition; decline in our stock price; and a significant restructuring charge within a reporting unit. Based upon our qualitative assessment, it is more likely than not that the fair value of our intangible assets are greater than the carrying amount as of December 31, 2018 . No impairment of our intangible assets were recorded in 2018 , 2017 or 2016 . Environmental Liabilities and Expenditures Accruals (charges to income) for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated, based upon current law and existing technologies. These amounts, which are not discounted and are exclusive of claims against third parties, are adjusted periodically as assessment and remediation efforts progress or additional technical or legal information becomes available. Environmental costs are capitalized if the costs increase the value of the property and/or mitigate or prevent contamination from future operations. Income Taxes Deferred taxes are provided for differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided to offset deferred tax assets if, based on the available evidence, it is more likely than not that some or all of the value of the deferred tax assets will not be realized. Derivative Financial Instruments We are exposed to market risk in the normal course of our business operations due to our purchases of certain commodities, our ongoing investing and financing activities and our operations that use foreign currencies. The risk of loss can be assessed from the perspective of adverse changes in fair values, cash flows and future earnings. We have established policies and procedures governing our management of market risks and the use of financial instruments to manage exposure to such risks. We use hedge accounting treatment for a significant amount of our business transactions whose risks are covered using derivative instruments. The hedge accounting treatment provides for the deferral of gains or losses on derivative instruments until such time as the related transactions occur. Concentration of Credit Risk Accounts receivable is the principal financial instrument which subjects us to a concentration of credit risk. Credit is extended based upon the evaluation of a customer’s financial condition and, generally, collateral is not required. Concentrations of credit risk with respect to receivables are somewhat limited due to our large number of customers, the diversity of these customers’ businesses and the geographic dispersion of such customers. Our accounts receivable are predominantly derived from sales denominated in USD or the Euro. We maintain an allowance for doubtful accounts based upon the expected collectibility of all trade receivables. Fair Value Fair value is defined as the price at which an asset could be exchanged in a current transaction between knowledgeable, willing parties or the amount that would be paid to transfer a liability to a new obligor, not the amount that would be paid to settle the liability with the creditor. Where available, fair value is based on observable market prices or parameters or derived from such prices or parameters. Where observable prices or inputs are not available, valuation models are applied. These valuation techniques involve some level of management estimation and judgment, the degree of which is dependent on the price transparency for the instruments or market and the instruments’ complexity. Assets and liabilities recorded at fair value in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels, defined by ASC 820 “Fair Value Measurement” (ASC 820), and directly related to the amount of subjectivity associated with the inputs to fair valuation of these assets and liabilities, are as follows: Level 1 — Inputs were unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 — Inputs (other than quoted prices included in Level 1) were either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. Level 3 — Inputs reflected management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration was given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. Retirement-Related Benefits We account for our defined benefit pension plans and non-pension postretirement benefit plans using actuarial models required by ASC 715 “Compensation—Retirement Benefits” (ASC 715). These models use an attribution approach that generally spreads the financial impact of changes to the plan and actuarial assumptions over the average remaining service lives of the employees in the plan. Changes in liability due to changes in actuarial assumptions such as discount rate, rate of compensation increases and mortality, as well as annual deviations between what was assumed and what was experienced by the plan are treated as actuarial gains or losses. The principle underlying the required attribution approach is that employees render service over their average remaining service lives on a relatively smooth basis and, therefore, the accounting for benefits earned under the pension or non-pension postretirement benefits plans should follow the same relatively smooth pattern. Substantially all domestic defined benefit pension plan participants are no longer accruing benefits; therefore, actuarial gains and losses are amortized based upon the remaining life expectancy of the inactive plan participants. For the years ended December 31, 2018 and 2017 , the average remaining life expectancy of the inactive participants in the domestic defined benefit pension plan were 18 and 19 years, respectively. One of the key assumptions for the net periodic pension calculation is the expected long-term rate of return on plan assets, used to determine the “market-related value of assets.” The “market-related value of assets” recognizes differences between the plan’s actual return and expected return over a five year period. The required use of an expected long-term rate of return on the market-related value of plan assets may result in recognized pension income that is greater or less than the actual returns of those plan assets in any given year. Over time, however, the expected long-term returns are designed to approximate the actual long-term returns and, therefore, result in a pattern of income and expense recognition that more closely matches the pattern of the services provided by the employees. As differences between actual and expected returns are recognized over five years, they subsequently generate gains and losses that are subject to amortization over the average remaining life expectancy of the inactive plan participants, as described in the preceding paragraph. We use long-term historical actual return information, the mix of investments that comprise plan assets, and future estimates of long-term investment returns and inflation by reference to external sources to develop the expected long-term rate of return on plan assets as of December 31. The discount rate assumptions used for pension and non-pension postretirement benefit plan accounting reflect the rates available on high-quality fixed-income debt instruments on December 31 of each year. The rate of compensation increase is based upon our long-term plans for such increases. For retiree medical plan accounting, we review external data and our own historical trends for healthcare costs to determine the healthcare cost trend rates. For our defined benefit pension and other postretirement benefit plans, we measure service and interest costs by applying the specific spot rates along the yield curve to the plans’ estimated cash flows. We believe this approach provides a more precise measurement of service and interest costs by aligning the timing of the plans’ liability cash flows to the corresponding spot rates on the yield curve. Stock-Based Compensation We measure the cost of employee services received in exchange for an award of equity instruments, such as stock options, performance shares and restricted stock, based on the grant-date fair value of the award. This cost is recognized over the period during which an employee is required to provide service in exchange for the award, the requisite service period (usually the vesting period). An initial measurement is made of the cost of employee services received in exchange for an award of liability instruments based on its current fair value and the value of that award is subsequently remeasured at each reporting date through the settlement date. Changes in fair value of liability awards during the requisite service period are recognized as compensation cost over that period. The fair value of each option granted, which typically vests ratably over three years, but not less than one year, was estimated on the date of grant, using the Black-Scholes option-pricing model with the following assumptions: 2018 2017 2016 Dividend yield 2.43 % 2.69 % 6.09 % Risk-free interest rate 2.72 % 2.06 % 1.35 % Expected volatility 32 % 34 % 32 % Expected life (years) 6.0 6.0 6.0 Weighted-average grant fair value (per option) $ 8.89 $ 7.78 $ 1.90 Weighted-average exercise price $ 32.94 $ 29.82 $ 13.14 Shares granted 927,000 1,621,000 1,670,400 Dividend yield was based on our current dividend yield as of the option grant date. Risk-free interest rate was based on zero coupon U.S. Treasury securities rates for the expected life of the options. Expected volatility was based on our historical stock price movements, as we believe that historical experience is the best available indicator of the expected volatility. Expected life of the option grant was based on historical exercise and cancellation patterns, as we believe that historical experience is the best estimate for future exercise patterns.

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	12 Months Ended
	Dec. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	NOTE 3 . RECENT ACCOUNTING PRONOUNCEMENTS In August 2018, the FASB issued ASU 2018-14, “Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans” which amends ASC 715. This update includes adding, clarifying and removing various disclosure requirements related to defined benefit pension and other postretirement plans. This update is effective for fiscal years beginning after December 15, 2020, with earlier application permitted. The guidance in this update is applied on a retrospective basis to all periods presented. We adopted this update on December 31, 2018. The adoption of this update did not have a material impact on our consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, “Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement” which amends ASC 820. This update includes adding, modifying and removing various disclosure requirements related to fair value measurements. This update is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with earlier application permitted. This update will be applied on a prospective basis for certain changes and retrospectively for other changes. We adopted this update on December 31, 2018. The adoption of this update did not have a material impact on our consolidated financial statements. In March 2018, the FASB issued ASU 2018-05, “Amendments to Securities and Exchange Commission (SEC) Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118” (SAB 118) which amends ASC 740 “Income Taxes.” This update codifies the guidance in SAB 118. SAB 118, “Income Tax Accounting Implications of the Tax Cuts and Jobs Act,” provided guidance for companies that have not completed their accounting for the income tax effects of U.S. Tax Cuts and Jobs Act (the 2017 Tax Act) in the period of enactment, allowing for a measurement period of up to one year after the enactment date to finalize the recording of the related tax impacts. During 2017, we recognized a provisional deferred tax benefit of $437.9 million , which was included as a component of income tax (benefit) provision. At December 31, 2018, we have completed our accounting for the tax effects of enactment of the 2017 Tax Act. During 2018, we increased the deferred tax benefit by $3.9 million as a result of filing the 2017 U.S. and foreign tax returns and decreased the deferred tax benefit by $0.1 million as a result of additional guidance issued by the Internal Revenue Service. In February 2018, FASB issued ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” which amends ASC 220 “Income Statement—Reporting Comprehensive Income.” This update allows a reclassification from accumulated other comprehensive loss to retained earnings for the stranded tax effects resulting from the 2017 Tax Act during each fiscal year or quarter in which the effect of the lower tax rate is recorded. The update is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with earlier application permitted. We adopted this update in March 2018 and reclassified $85.9 million related to the deferred gain resulting from the 2017 Tax Act from accumulated other comprehensive loss to retained earnings. In August 2017, the FASB issued ASU 2017-12, “Targeted Improvements to Accounting for Hedge Activities” which amends ASC 815 “Derivatives and Hedging” (ASC 815). This update is intended to more closely align hedge accounting with companies’ risk management strategies, simplify the application of hedge accounting guidance, and increase transparency as to the scope and results of hedge programs. The update is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with earlier application permitted. We adopted this update on January 1, 2018. The adoption of this update did not have a material impact on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-07, “Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” which amends ASC 715. This update requires the presentation of the service cost component of net periodic benefit (income) costs in the same income statement line item as other employee compensation costs arising from services rendered during the period. The update requires the presentation of the other components of the net periodic benefit (income) costs separately from the line item that includes the service cost and outside of any subtotal of operating income. The update is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The guidance in this update is applied on a retrospective basis with earlier application permitted. We adopted this update on January 1, 2018 using the retrospective method. The adoption of ASU 2017-07 resulted in a change in our net periodic benefit (income) costs within operating income, which was offset by a corresponding change in non-operating pension income to reflect the impact of presenting the interest cost, expected return on plan assets and amortization of prior service cost and net actuarial loss components of net periodic benefit (income) costs outside of operating income. For the years ended December 31, 2017 and 2016, the adoption of ASU 2017-07 resulted in a reclassification of $15.3 million and $20.8 million , respectively, from cost of goods sold, and $19.1 million and $24.0 million , respectively, from selling and administration expenses to non-operating pension income reflecting the aforementioned reclassification on our consolidated statements of operations. The service cost component of net periodic benefit (income) costs continues to be included in the same income statement line item as other employee compensation costs arising from services rendered during the period. In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment” which amends ASC 350. This update will simplify the measurement of goodwill impairment by eliminating Step 2 from the goodwill impairment test. This update will require an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. The update does not modify the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. This update is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The guidance in this update is applied on a prospective basis with earlier application permitted. We plan to adopt this update on January 1, 2020 and do not expect the update to have a material impact on our consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, “Classification of Certain Cash Receipts and Cash Payments” which amends ASC 230 “Statement of Cash Flows.” This update will make eight targeted changes to how cash receipts and cash payments are presented and classified in the statement of cash flows. The update is effective for fiscal years beginning after December 15, 2017. The update will require adoption on a retrospective basis unless it is impracticable to apply, in which case it would be required to apply the amendments prospectively as of the earliest date practicable. We adopted this update on January 1, 2018. In connection with this update, we made an accounting policy election to apply the nature of the distribution approach when determining the proper classification of distributions received from equity method investments. The adoption of this update did not have a material impact on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02 “Leases,” (ASU 2016-02) which supersedes ASC 840 “Leases” and creates a new topic, ASC 842 “Leases.” Subsequent to the issuance of ASU 2016-02, ASC 842 was amended by various updates that amend and clarify the impact and implementation of the aforementioned update. These updates require lessees to recognize a lease liability and a lease asset for all leases, including operating leases, with a term greater than 12 months on its balance sheet. Upon initial application, the provisions of these updates are required to be applied using the modified retrospective method which requires retrospective adoption to each prior reporting period presented with the cumulative effect of adoption recorded to the earliest reporting period presented. An optional transition method can be utilized which requires retrospective adoption beginning on the date of adoption with the cumulative effect of initially applying these updates recognized at the date of initial adoption. These updates also expand the required quantitative and qualitative disclosures surrounding leases. These updates are effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, with earlier application permitted. We adopted these updates on January 1, 2019 using the optional transition method. Adoption of these updates resulted in the recording of additional operating lease assets and lease liabilities on our consolidated balance sheet of between approximately $275 million and $325 million as of January 1, 2019. Our assets and liabilities for finance leases remained unchanged. We also recognized the cumulative effect of applying these updates as an adjustment to retained earnings of between approximately $10 million and $15 million , net of the deferred tax impact, primarily related to the recognition of previously deferred sale/leaseback gains. Our consolidated statements of operations and cash flows were not impacted by this adoption. These updates also impacted our accounting policies, internal controls and disclosures related to leases. In May 2014, the FASB issued ASU 2014-09 “Revenue from Contracts with Customers” (ASU 2014-09), which amends ASC 605 “Revenue Recognition” and creates a new topic, ASC 606 “Revenue from Contracts with Customers” (ASC 606). Subsequent to the issuance of ASU 2014-09, ASC 606 was amended by various updates that amend and clarify the impact and implementation of the aforementioned update. These updates provide guidance on how an entity should recognize revenue to depict the transfer of control of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Upon initial application, the provisions of these updates are required to be applied retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying this update recognized at the date of initial application. These updates also expand the disclosure requirements surrounding revenue recorded from contracts with customers. These updates are effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. We adopted these updates on January 1, 2018 using the modified retrospective transition method. The cumulative effect of applying the updates did not have a material impact on our consolidated financial statements. The most significant impact the updates had was on our accounting policies and disclosures on revenue recognition. Expanded disclosures regarding revenue recognition are included within our consolidated financial statements.

ACQUISITION

ACQUISITION	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
ACQUISITION	NOTE 4 . ACQUISITION On October 5, 2015 (the Closing Date), we completed the acquisition (the Acquisition) from DowDuPont Inc. (DowDuPont) (f/k/a The Dow Chemical Company) of its U.S. Chlor Alkali and Vinyl, Global Chlorinated Organics and Global Epoxy businesses (collectively, the Acquired Business), whose operating results are included in the accompanying financial statements since the Closing Date. We finalized our purchase price allocation of the Acquired Business during the third quarter of 2016. For the year ended December 31, 2016, the aggregate purchase price was adjusted for the final working capital adjustment and the final valuation for the pension liabilities assumed from DowDuPont which resulted in a payment of $69.5 million . For the years ended December 31, 2018 , 2017 and 2016 , we incurred costs related to the integration of the Acquired Business of $1.0 million , $12.8 million and $48.8 million , respectively, which consisted of advisory, legal, accounting and other professional fees.

RESTRUCTURING CHARGES

RESTRUCTURING CHARGES	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
RESTRUCTURING CHARGES	NOTE 5 . RESTRUCTURING CHARGES On December 10, 2018, we announced that we had made the decision to permanently close the ammunition assembly operations at our Winchester facility in Geelong, Australia. Subsequent to the facility’s closure, product for customers in the region will be sourced from Winchester manufacturing facilities located in the United States. For the year ended December 31, 2018 , we recorded pretax restructuring charges of $4.1 million for the write-off of equipment and facility costs, employee severance and related benefit costs and lease and other contract termination costs related to this action. We expect to incur additional restructuring charges through 2019 of approximately $1 million related to this closure. On March 21, 2016, we announced that we had made the decision to close a combined total of 433,000 tons of chlor alkali capacity across three separate locations. Associated with this action, we have permanently closed our Henderson, NV chlor alkali plant with 153,000 tons of capacity and have reconfigured the site to manufacture bleach and distribute caustic soda and hydrochloric acid. Also, the capacity of our Niagara Falls, NY chlor alkali plant has been reduced from 300,000 tons to 240,000 tons and the chlor alkali capacity at our Freeport, TX facility was reduced by 220,000 tons. This 220,000 ton reduction was entirely from diaphragm cell capacity. For the years ended December 31, 2018 , 2017 and 2016 , we recorded pretax restructuring charges of $15.7 million , $32.6 million and $111.3 million , respectively, for the write-off of equipment and facility costs, lease and other contract termination costs, employee severance and related benefit costs, employee relocation costs and facility exit costs related to these actions. We expect to incur additional restructuring charges through 2019 of approximately $10 million related to these capacity reductions. For the years ended December 31, 2018 , 2017 and 2016 , we recorded pretax restructuring charges of $2.1 million , $3.3 million and $0.8 million , respectively, for lease and other contract termination costs and facility exit costs related to our permanent reduction in capacity at our Becancour, Canada chlor alkali facility in 2014. We expect to incur additional restructuring charges through 2019 of less than $1 million related to this action. For the years ended December 31, 2017 and 2016 , we recorded pretax restructuring charges of $1.7 million and $0.8 million , respectively, for employee severance and related benefit costs, employee relocation costs and facility exit costs related to the relocation of our Winchester centerfire pistol and rifle ammunition manufacturing operations from East Alton, IL to Oxford, MS that was announced in 2010 and completed in 2016. The following table summarizes the 2018 , 2017 and 2016 activities by major component of these restructuring actions and the remaining balances of accrued restructuring costs as of December 31, 2018 : Employee severance and related benefit costs Lease and other contract termination costs Employee relocation costs Facility exit costs Write-off of equipment and facility Total ($ in millions) Balance at January 1, 2016 $ 4.6 $ 2.1 $ — $ — $ — $ 6.7 2016 restructuring charges 5.1 13.6 2.1 15.5 76.6 112.9 Amounts utilized (6.3 ) (8.2 ) (2.1 ) (13.7 ) (76.6 ) (106.9 ) Balance at December 31, 2016 3.4 7.5 — 1.8 — 12.7 2017 restructuring charges 2.0 22.1 0.3 11.7 1.5 37.6 Amounts utilized (3.6 ) (26.3 ) (0.3 ) (13.5 ) (1.5 ) (45.2 ) Balance at December 31, 2017 1.8 3.3 — — — 5.1 2018 restructuring charges 1.7 5.6 — 12.0 2.6 21.9 Amounts utilized (2.0 ) (2.9 ) — (11.3 ) (2.6 ) (18.8 ) Balance at December 31, 2018 $ 1.5 $ 6.0 $ — $ 0.7 $ — $ 8.2 The following table summarizes the cumulative restructuring charges of these 2018, 2016, 2014 and 2010 restructuring actions by major component through December 31, 2018 : Chlor Alkali Products and Vinyls Winchester Total Becancour Capacity Reductions Oxford Geelong ($ in millions) Write-off of equipment and facility $ 3.5 $ 78.1 $ — $ 2.6 $ 84.2 Employee severance and related benefit costs 2.7 5.9 14.7 1.3 24.6 Facility exit costs 5.9 33.8 2.3 — 42.0 Pension and other postretirement benefits curtailment — — 4.1 — 4.1 Employee relocation costs — 1.7 6.0 — 7.7 Lease and other contract termination costs 6.1 40.2 — 0.2 46.5 Total cumulative restructuring charges $ 18.2 $ 159.7 $ 27.1 $ 4.1 $ 209.1 As of December 31, 2018 , we have incurred cash expenditures of $112.2 million and non-cash charges of $88.7 million related to these restructuring actions. The remaining balance of $8.2 million is expected to be paid out through 2020.

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
EARNINGS PER SHARE	NOTE 6 . EARNINGS PER SHARE Basic and diluted income (loss) per share are computed by dividing net income (loss) by the weighted-average number of common shares outstanding. Diluted net income (loss) per share reflects the dilutive effect of stock-based compensation. Years ended December 31, 2018 2017 2016 Computation of Income (Loss) per Share (In millions, except per share data) Net income (loss) $ 327.9 $ 549.5 $ (3.9 ) Basic shares 166.8 166.2 165.2 Basic net income (loss) per share $ 1.97 $ 3.31 $ (0.02 ) Diluted shares: Basic shares 166.8 166.2 165.2 Stock-based compensation 1.6 2.3 — Diluted shares 168.4 168.5 165.2 Diluted net income (loss) per share $ 1.95 $ 3.26 $ (0.02 ) The computation of dilutive shares from stock-based compensation does not include 2.4 million , 1.6 million and 6.5 million shares in 2018 , 2017 and 2016 , respectively, as their effect would have been anti-dilutive.

ACCOUNTS RECEIVABLES

ACCOUNTS RECEIVABLES	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
ACCOUNTS RECEIVABLES	NOTE 7 . ACCOUNTS RECEIVABLES On December 20, 2016, we entered into a three -year, $250.0 million Receivables Financing Agreement with PNC Bank, National Association, as administrative agent (Receivables Financing Agreement). Under the Receivables Financing Agreement, our eligible trade receivables are used for collateralized borrowings and continue to be serviced by us. In addition, the Receivables Financing Agreement incorporates the leverage and coverage covenants that are contained in the senior revolving credit facility. As of December 31, 2018 and 2017 , $360.4 million and $340.9 million , respectively, of our trade receivables were pledged as collateral and we had $125.0 million and $249.7 million , respectively, drawn under the agreement. As of December 31, 2018 , we had $125.0 million of additional borrowing capacity under the Receivables Financing Agreement. Olin also has trade accounts receivable factoring arrangements (AR Facilities) and pursuant to the terms of the AR Facilities, certain of our subsidiaries may sell their accounts receivable up to a maximum of $315.0 million . We will continue to service the outstanding accounts sold. These receivables qualify for sales treatment under ASC 860 “Transfers and Servicing” and, accordingly, the proceeds are included in net cash provided by operating activities in the consolidated statements of cash flows. The following table summarizes the AR Facilities activity: December 31, 2018 2017 ($ in millions) Beginning Balance $ 182.3 $ 126.1 Gross receivables sold 1,372.3 1,655.2 Payments received from customers on sold accounts (1,422.2 ) (1,599.0 ) Ending Balance $ 132.4 $ 182.3 The factoring discount paid under the AR Facilities is recorded as interest expense on the consolidated statements of operations. The factoring discount for the years ended December 31, 2018 , 2017 and 2016 was $4.3 million , $3.7 million and $1.1 million , respectively. The agreements are without recourse and therefore no recourse liability has been recorded as of December 31, 2018 . At December 31, 2018 and 2017 , our consolidated balance sheets included other receivables of $58.0 million and $105.5 million , respectively, which were classified as receivables, net.

ALLOWANCE FOR DOUBTFUL ACCOUNTS

ALLOWANCE FOR DOUBTFUL ACCOUNTS RECEIVABLES	12 Months Ended
	Dec. 31, 2018
Accounts Receivable, Net [Abstract]
ALLOWANCE FOR DOUBTFUL ACCOUNTS RECEIVABLES	NOTE 8 . ALLOWANCE FOR DOUBTFUL ACCOUNTS RECEIVABLES Allowance for doubtful accounts receivable consisted of the following: December 31, 2018 2017 ($ in millions) Beginning balance $ 12.3 $ 10.1 Provisions charged 1.7 1.8 Write-offs, net of recoveries (0.7 ) (0.1 ) Foreign currency translation adjustments (0.4 ) 0.5 Ending balance $ 12.9 $ 12.3

INVENTORIES

INVENTORIES	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
INVENTORIES	NOTE 9 . INVENTORIES December 31, 2018 2017 ($ in millions) Supplies $ 66.4 $ 66.1 Raw materials 66.7 75.3 Work in process 139.6 127.8 Finished goods 488.5 462.6 761.2 731.8 LIFO reserve (49.8 ) (49.2 ) Inventories, net $ 711.4 $ 682.6 Inventories valued using the LIFO method comprised 55% of the total inventories at both December 31, 2018 and 2017 . The replacement cost of our inventories would have been approximately $49.8 million and $49.2 million higher than that reported at December 31, 2018 and 2017 , respectively.

OTHER ASSETS

OTHER ASSETS	12 Months Ended
	Dec. 31, 2018
Other Assets [Abstract]
OTHER ASSETS	NOTE 10 . OTHER ASSETS Included in other assets were the following: December 31, 2018 2017 ($ in millions) Supply contracts $ 1,099.5 $ 1,137.1 Investments in non-consolidated affiliates 8.8 28.5 Other 42.1 42.8 Other assets $ 1,150.4 $ 1,208.4 For the year ended December 31, 2018 , we recorded a $21.5 million non-cash impairment charge related to an adjustment to the value of our 9.1% limited partnership interest in Bay Gas Storage Company, Ltd. (Bay Gas). Bay Gas owns, leases and operates underground gas storage and related pipeline facilities, which are used to provide storage in the McIntosh, AL area and delivery of natural gas. The general partner, Sempra Energy (Sempra), announced in the second quarter of 2018 its plan to sell several assets including its 90.9% interest in Bay Gas. In connection with this decision, Sempra recorded an impairment charge related to Bay Gas adjusting the related assets’ carrying values to an estimated fair value. We recorded a reduction in our investment in the non-consolidated affiliate for the proportionate share of the non-cash impairment charge. Olin has no other non-consolidated affiliates. The losses of non-consolidated affiliates were $19.7 million for the year ended December 31, 2018 , which reflect a $21.5 million non-cash impairment charge recorded during 2018. The earnings of non-consolidated affiliates were $1.8 million and $1.7 million for the years ended December 31, 2017 and 2016, respectively. On January 1, 2019, we entered into an agreement to sell our 9.1% limited partnership interest in Bay Gas for approximately $20 million . The sale closed on February 7, 2019 which resulted in a gain of approximately $11 million which will be included in first quarter 2019 results. In connection with the Acquisition, Olin and DowDuPont entered into arrangements for the long-term supply of ethylene by DowDuPont to Olin, pursuant to which, among other things, Olin made upfront payments of $433.5 million on the Closing Date in order to receive ethylene at producer economics and for certain reservation fees and for the option to obtain additional ethylene at producer economics. The fair value of the long-term supply contracts recorded as of the Closing Date was a long-term asset of $416.1 million which will be amortized over the life of the contracts as ethylene is received. During 2017, we made an additional payment of $209.4 million in connection with our option to reserve additional ethylene supply at producer economics from DowDuPont which increased the value of the long-term asset. On February 27, 2017, we also exercised the remaining option to obtain additional future ethylene at producer economics from DowDuPont. In connection with the exercise of this option, we also secured a long-term customer arrangement. As a result, an additional payment will be made to DowDuPont of between $440 million and $465 million on or about the fourth quarter of 2020. During September 2017, as a result of DowDuPont’s new Texas 9 ethylene cracker becoming operational, Olin recognized a long-term asset and other liabilities of $389.2 million , which represents the present value of the additional estimated payment. The discounted amount of $51.8 million will be recorded as interest expense through the fourth quarter of 2020. For the years ended December 31, 2018 and 2017 , interest expense of $16.0 million and $3.9 million , respectively, was recorded for accretion on the 2020 payment discount. During 2016, Olin entered into arrangements to increase our supply of low cost electricity. In conjunction with these arrangements, Olin made payments of $175.7 million in 2016. The payments made under these arrangements will be amortized over the life of the contracts as electrical power is received. The weighted-average useful life of long-term supply contracts at December 31, 2018 was 20 years. For the years ended December 31, 2018 , 2017 and 2016 , amortization expense of $37.6 million , $28.2 million and $21.5 million , respectively, was recognized within cost of goods sold related to these supply contracts and is reflected in depreciation and amortization on the consolidated statements of cash flows. We estimate that amortization expense will be approximately $38 million in 2019 and 2020 and $60 million in 2021 , 2022 and 2023 related to these long-term supply contracts. The long-term supply contracts are monitored for impairment each reporting period.

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	NOTE 11 . PROPERTY, PLANT AND EQUIPMENT December 31, Useful Lives 2018 2017 ($ in millions) Land and improvements to land 10-20 Years $ 276.9 $ 281.7 Buildings and building equipment 10-30 Years 387.6 382.4 Machinery and equipment 3-20 Years 5,252.0 5,028.4 Leasehold improvements 5.2 3.9 Construction in progress 341.4 212.5 Property, plant and equipment 6,263.1 5,908.9 Accumulated depreciation (2,781.0 ) (2,333.1 ) Property, plant and equipment, net $ 3,482.1 $ 3,575.8 The weighted-average useful life of machinery and equipment at December 31, 2018 was 11 years. Depreciation expense was $497.8 million , $465.1 million and $435.7 million for 2018 , 2017 and 2016 , respectively. Interest capitalized was $6.0 million , $3.0 million and $1.9 million for 2018 , 2017 and 2016 , respectively. The consolidated statements of cash flows for the years ended December 31, 2018 , 2017 and 2016 , included decreases of $25.5 million , $0.5 million and $29.9 million , respectively, to capital expenditures, with the corresponding change to accounts payable and accrued liabilities, related to purchases of property, plant and equipment included in accounts payable and accrued liabilities at December 31, 2018 , 2017 and 2016 . During 2016, we entered into sale/leaseback transactions for railcars that we acquired in connection with the Acquisition. We received proceeds from the sales of $40.4 million for the year ended December 31, 2016.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	NOTE 12 . GOODWILL AND INTANGIBLE ASSETS Changes in the carrying value of goodwill were as follows: Chlor Alkali Products and Vinyls Epoxy Total ($ in millions) Balance at January 1, 2017 $ 1,831.3 $ 286.7 $ 2,118.0 Foreign currency translation adjustment 1.6 0.4 2.0 Balance at December 31, 2017 1,832.9 287.1 2,120.0 Foreign currency translation adjustment (0.3 ) (0.1 ) (0.4 ) Balance at December 31, 2018 $ 1,832.6 $ 287.0 $ 2,119.6 Intangible assets consisted of the following: December 31, 2018 2017 Useful Lives Gross Amount Accumulated Amortization Net Gross Amount Accumulated Amortization Net ($ in millions) Customers, customer contracts and relationships 10-15 Years $ 675.2 $ (211.9 ) $ 463.3 $ 679.5 $ (163.6 ) $ 515.9 Trade name 5 Years 7.0 (4.6 ) 2.4 7.1 (3.2 ) 3.9 Acquired technology 7 Years 85.4 (39.6 ) 45.8 86.1 (27.7 ) 58.4 Other 10 Years 0.7 (0.6 ) 0.1 2.3 (2.0 ) 0.3 Total intangible assets $ 768.3 $ (256.7 ) $ 511.6 $ 775.0 $ (196.5 ) $ 578.5 In connection with the integration of the Acquired Business, in the first quarter of 2016, the K.A. Steel Chemicals Inc. trade name was changed from an indefinite life intangible asset to an intangible asset with a finite useful life of one year. Amortization expense of $10.9 million was recognized within cost of goods sold for the year ended December 31, 2016 related to the change in useful life. Amortization expense relating to intangible assets was $62.8 million , $62.8 million and $73.8 million in 2018 , 2017 and 2016 , respectively. We estimate that amortization expense will be approximately $63 million in 2019 and 2020 , approximately $61 million in 2021 , approximately $54 million in 2022 and approximately $35 million in 2023 .

DEBT

DEBT	12 Months Ended
	Dec. 31, 2018
Debt Instruments [Abstract]
DEBT	NOTE 13 . DEBT Long-Term Debt December 31, 2018 2017 Notes payable: ($ in millions) Variable-rate Senior Term Loan Facility, due 2022 (4.02% and 3.57% at December 31, 2018 and 2017, respectively) $ 543.0 $ 1,323.4 Variable-rate Recovery Zone bonds, due 2024-2035 (3.67% and 3.27% at December 31, 2018 and 2017, respectively) 103.0 103.0 Variable-rate Go Zone bonds, due 2024 (3.67% and 3.27% at December 31, 2018 and 2017, respectively) 50.0 50.0 Variable-rate Industrial development and environmental improvement obligations, due 2025 (2.52% and 1.27% at December 31, 2018 and 2017, respectively) 2.9 2.9 9.75%, due 2023 720.0 720.0 10.00%, due 2025 500.0 500.0 5.50%, due 2022 200.0 200.0 5.125%, due 2027 500.0 500.0 5.00%, due 2030 550.0 — Senior Revolving Credit Facility — 20.0 Receivables Financing Agreement 125.0 249.7 Capital lease obligations 4.2 3.7 Total notes payable 3,298.1 3,672.7 Deferred debt issuance costs (34.1 ) (32.6 ) Interest rate swaps (33.7 ) (28.1 ) Total debt 3,230.3 3,612.0 Amounts due within one year 125.9 0.7 Total long-term debt $ 3,104.4 $ 3,611.3 On January 19, 2018, Olin issued $550.0 million aggregate principal amount of 5.00% senior notes due February 1, 2030 (2030 Notes), which were registered under the Securities Act of 1933, as amended. Interest on the 2030 Notes began accruing from January 19, 2018 and is paid semi-annually beginning on August 1, 2018. Proceeds from the 2030 Notes were used to redeem $550.0 million of debt under the $1,375.0 million term loan facility (Term Loan Facility). For the year ended December 31, 2018 , we recognized interest expense of $2.6 million for the write-off of unamortized deferred debt issuance costs related to the redemption of $550.0 million of debt under the Term Loan Facility. On March 9, 2017, we entered into a new five -year $1,975.0 million senior credit facility, which amended and restated the existing $1,850.0 million senior credit facility. We recognized interest expense of $1.2 million for the write-off of unamortized deferred debt issuance costs related to this action during 2017. Pursuant to the agreement, the aggregate principal amount under the term loan facility was increased to $1,375.0 million , and the aggregate commitments under the senior revolving credit facility were increased to $600.0 million (Senior Revolving Credit Facility and, together with the Term Loan Facility, the Senior Credit Facility), from $500.0 million . At December 31, 2018 , we had $596.5 million available under our $600.0 million Senior Revolving Credit Facility because we had issued $3.5 million of letters of credit. In March 2017, we drew the entire $1,375.0 million term loan and used the proceeds to redeem the remaining balance of the existing $1,350.0 million senior credit facility of $1,282.5 million and a portion of the $800.0 million Sumitomo Credit Facility (Sumitomo Credit Facility). The maturity date for the Senior Credit Facility was extended from October 5, 2020 to March 9, 2022. The $600.0 million Senior Revolving Credit Facility includes a $100.0 million letter of credit subfacility. The Term Loan Facility included amortization payable in equal quarterly installments at a rate of 5.0% per annum for the first two years, increasing to 7.5% per annum for the following year and to 10.0% per annum for the last two years. However, in connection with the $550.0 million prepayment of the Term Loan Facility in January 2018, the required quarterly installments of the Term Loan Facility were eliminated. For the years ended December 31, 2017 and 2016 , we repaid $51.6 million and $67.5 million , respectively, under the required quarterly installments of the term loan facilities. Under the Senior Credit Facility, we may select various floating rate borrowing options. The actual interest rate paid on borrowings under the Senior Credit Facility is based on a pricing grid which is dependent upon the leverage ratio as calculated under the terms of the applicable facility for the prior fiscal quarter. The facility includes various customary restrictive covenants, including restrictions related to the ratio of debt to earnings before interest expense, taxes, depreciation and amortization (leverage ratio) and the ratio of earnings before interest expense, taxes, depreciation and amortization to interest expense (coverage ratio). Compliance with these covenants is determined quarterly based on the operating cash flows. We were in compliance with all covenants and restrictions under all our outstanding credit agreements as of December 31, 2018 and 2017 , and no event of default had occurred that would permit the lenders under our outstanding credit agreements to accelerate the debt if not cured. In the future, our ability to generate sufficient operating cash flows, among other factors, will determine the amounts available to be borrowed under these facilities. As of December 31, 2018 , there were no covenants or other restrictions that would have limited our ability to borrow under these facilities. On March 9, 2017, Olin issued $500.0 million aggregate principal amount of 5.125% senior notes due September 15, 2027 (2027 Notes), which were registered under the Securities Act of 1933, as amended. Interest on the 2027 Notes began accruing from March 9, 2017 and is paid semi-annually beginning on September 15, 2017. Proceeds from the 2027 Notes were used to redeem the remaining balance of the Sumitomo Credit Facility. On December 20, 2016, we entered into a three -year, $250.0 million Receivables Financing Agreement. Under the Receivables Financing Agreement, our eligible trade receivables are used for collateralized borrowings and continue to be serviced by us. In addition, the Receivables Financing Agreement incorporates the leverage and coverage covenants that are contained in the senior revolving credit facility. As of December 31, 2018 and 2017 , $360.4 million and $340.9 million , respectively, of our trade receivables were pledged as collateral and we had $125.0 million and $249.7 million , respectively, drawn under the agreement. As of December 31, 2018 , we had $125.0 million of additional borrowing capacity under the Receivables Financing Agreement. For the year ended December 31, 2017 , we borrowed $40.0 million under the Receivables Financing Agreement and used the proceeds to fund a portion of the payment to DowDuPont associated with a long-term ethylene supply contract to reserve additional ethylene at producer economics. For the year ended December 31, 2016 , the proceeds of the Receivables Financing Agreement were used to repay $210.0 million of the Sumitomo Credit Facility. During 2016, $210.0 million was repaid under the Sumitomo Credit Facility using proceeds from the Receivables Financing Agreement. During 2017, the remaining balance of $590.0 million was repaid using proceeds from the Senior Credit Facility and the 2027 Notes. We recognized interest expense of $1.5 million related to the write-off of unamortized deferred debt issuance costs related to this action in 2017. In June 2016, we repaid $125.0 million of 6.75% senior notes due 2016, which became due. In 2018, we paid debt issuance costs of $8.5 million relating to the 2030 Notes. In 2017, we paid debt issuance costs of $11.2 million relating to the Senior Credit Facility and the 2027 Notes. In 2016, we paid debt issuance costs of $1.0 million for the registration of the $720.0 million aggregate principal amount of 9.75% senior notes due October 15, 2023 and $500.0 million aggregate principal amount of 10.00% senior notes due October 15, 2025 under the Securities Act of 1933. Pursuant to a note purchase agreement dated December 22, 1997, SunBelt sold $97.5 million of Guaranteed Senior Secured Notes due 2017, Series O, and $97.5 million of Guaranteed Senior Secured Notes due 2017, Series G. We refer to these notes as the SunBelt Notes. The SunBelt Notes accrued interest at a rate of 7.23% per annum, payable semi-annually in arrears on each June 22 and December 22. In December 2017 and 2016 , $12.2 million was repaid on these SunBelt Notes. At December 31, 2017 , all amounts due under the SunBelt Notes had been repaid. At December 31, 2018 , we had total letters of credit of $74.7 million outstanding, of which $3.5 million were issued under our Senior Revolving Credit Facility. The letters of credit are used to support certain long-term debt, certain workers compensation insurance policies, certain plant closure and post-closure obligations and certain international pension funding requirements. Annual maturities of long-term debt, including capital lease obligations, are $125.9 million in 2019 , $1.8 million in 2020 , $0.5 million in 2021 , $743.4 million in 2022 , $720.3 million in 2023 and a total of $1,706.2 million thereafter. In April 2016, we entered into three tranches of forward starting interest rate swaps whereby we agreed to pay fixed rates to the counterparties who, in turn, pay us floating rates on $1,100.0 million , $900.0 million , and $400.0 million of our underlying floating-rate debt obligations. Each tranche’s term length is for twelve months beginning on December 31, 2016, December 31, 2017, and December 31, 2018, respectively. The counterparties to the agreements are SMBC Capital Markets, Inc., Wells Fargo Bank, N.A. (Wells Fargo), PNC Bank, National Association, and Toronto-Dominion Bank. These counterparties are large financial institutions. We have designated the swaps as cash flow hedges of the risk of changes in interest payments associated with our variable-rate borrowings. Accordingly, the remaining swap agreement has been recorded at its fair market value of $5.3 million and is included in other current assets on the accompanying consolidated balance sheet, with the corresponding gain deferred as a component of other comprehensive loss. For the years ended December 31, 2018 and 2017 , $8.9 million and $3.1 million , respectively, of income was recorded to interest expense on the accompanying consolidated statements of operations related to these swap agreements. In April 2016, we entered into interest rate swaps on $250.0 million of our underlying fixed-rate debt obligations, whereby we agreed to pay variable rates to the counterparties who, in turn, pay us fixed rates. The counterparties to these agreements are Toronto-Dominion Bank and SMBC Capital Markets, Inc., both of which are major financial institutions. In October 2016, we entered into interest rate swaps on an additional $250.0 million of our underlying fixed-rate debt obligations, whereby we agreed to pay variable rates to the counterparties who, in turn, pay us fixed rates. The counterparties to these agreements are PNC Bank, National Association and Wells Fargo, both of which are major financial institutions. We have designated the April 2016 and October 2016 interest rate swap agreements as fair value hedges of the risk of changes in the value of fixed rate debt due to changes in interest rates for a portion of our fixed rate borrowings. Accordingly, the swap agreements have been recorded at their fair market value of $33.7 million and are included in other long-term liabilities on the accompanying consolidated balance sheet, with a corresponding decrease in the carrying amount of the related debt. For the year ended December 31, 2018 , $2.1 million of expense has been recorded to interest expense on the accompanying consolidated statements of operations related to these swap agreements. For the years ended December 31, 2017 and 2016, $2.9 million and $2.6 million , respectively, of income has been recorded to interest expense on the accompanying consolidated statements of operations related to these swap agreements. Our loss in the event of nonperformance by these counterparties could be significant to our financial position and results of operations. Our interest rate swaps reduced interest expense by $6.8 million , $6.1 million and $3.7 million in 2018 , 2017 and 2016 , respectively. The difference between interest paid and interest received is included as an adjustment to interest expense.

PENSION PLANS

PENSION PLANS	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
PENSION PLANS	NOTE 14 . PENSION PLANS We sponsor domestic and foreign defined benefit pension plans for eligible employees and retirees. Most of our domestic employees participate in defined contribution plans. However, a portion of our bargaining hourly employees continue to participate in our domestic qualified defined benefit pension plans under a flat-benefit formula. Our funding policy for the qualified defined benefit pension plans is consistent with the requirements of federal laws and regulations. Our foreign subsidiaries maintain pension and other benefit plans, which are consistent with local statutory practices. Our domestic qualified defined benefit pension plan provides that if, within three years following a change of control of Olin, any corporate action is taken or filing made in contemplation of, among other things, a plan termination or merger or other transfer of assets or liabilities of the plan, and such termination, merger or transfer thereafter takes place, plan benefits would automatically be increased for affected participants (and retired participants) to absorb any plan surplus (subject to applicable collective bargaining requirements). During 2016, we made a discretionary cash contribution to our domestic qualified defined benefit pension plan of $6.0 million . Based on our plan assumptions and estimates, we will not be required to make any cash contributions to the domestic qualified defined benefit pension plan at least through 2019 . We have international qualified defined benefit pension plans to which we made cash contributions of $2.6 million , $1.7 million and $1.3 million in 2018 , 2017 and 2016 , respectively, and we anticipate less than $5 million of cash contributions to international qualified defined benefit pension plans in 2019 . Pension Obligations and Funded Status Changes in the benefit obligation and plan assets were as follows: December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total Change in Benefit Obligation ($ in millions) Benefit obligation at beginning of year $ 2,579.9 $ 303.4 $ 2,883.3 $ 2,466.2 $ 251.0 $ 2,717.2 Service cost 1.4 9.7 11.1 1.2 8.2 9.4 Interest cost 80.6 5.7 86.3 81.3 5.3 86.6 Actuarial (gain) loss (163.2 ) 1.5 (161.7 ) 161.7 9.6 171.3 Benefits paid (133.2 ) (3.7 ) (136.9 ) (130.5 ) (4.2 ) (134.7 ) Plan participant’s contributions — 1.2 1.2 — 1.0 1.0 Plan amendments — (0.4 ) (0.4 ) — 1.7 1.7 Foreign currency translation adjustments — (15.1 ) (15.1 ) — 30.8 30.8 Benefit obligation at end of year $ 2,365.5 $ 302.3 $ 2,667.8 $ 2,579.9 $ 303.4 $ 2,883.3 December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total Change in Plan Assets ($ in millions) Fair value of plans’ assets at beginning of year $ 2,172.5 $ 74.4 $ 2,246.9 $ 2,012.0 $ 66.5 $ 2,078.5 Actual return on plans’ assets (113.9 ) (2.1 ) (116.0 ) 290.6 5.0 295.6 Employer contributions 0.4 1.8 2.2 0.4 2.2 2.6 Benefits paid (133.2 ) (2.2 ) (135.4 ) (130.5 ) (3.0 ) (133.5 ) Foreign currency translation adjustments — (4.7 ) (4.7 ) — 3.7 3.7 Fair value of plans’ assets at end of year $ 1,925.8 $ 67.2 $ 1,993.0 $ 2,172.5 $ 74.4 $ 2,246.9 December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total Funded Status ($ in millions) Qualified plans $ (436.1 ) $ (232.8 ) $ (668.9 ) $ (403.7 ) $ (226.9 ) $ (630.6 ) Non-qualified plans (3.6 ) (2.3 ) (5.9 ) (3.7 ) (2.1 ) (5.8 ) Total funded status $ (439.7 ) $ (235.1 ) $ (674.8 ) $ (407.4 ) $ (229.0 ) $ (636.4 ) Under ASC 715, we recorded a $76.5 million after-tax charge ( $100.6 million pretax) to shareholders’ equity as of December 31, 2018 for our pension plans. This charge primarily reflected unfavorable performance on plan assets during 2018 , partially offset by a 60 -basis point increase in the domestic pension plans’ discount rate. In 2017 , we recorded a $21.3 million after-tax charge ( $26.9 million pretax) to shareholders’ equity as of December 31, 2017 for our pension plans. This charge primarily reflected a 50 -basis point decrease in the domestic pension plans’ discount rate, partially offset by favorable performance on plan assets during 2017. The $161.7 million actuarial gain for 2018 was primarily due to a 60 -basis point increase in the domestic pension plans’ discount rate. The $171.3 million actuarial loss for 2017 was primarily due to a 50 -basis point decrease in the domestic pension plans’ discount rate. Amounts recognized in the consolidated balance sheets consisted of: December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total ($ in millions) Accrued benefit in current liabilities $ (0.4 ) $ (0.1 ) $ (0.5 ) $ (0.4 ) $ (0.1 ) $ (0.5 ) Accrued benefit in noncurrent liabilities (439.3 ) (235.0 ) (674.3 ) (407.0 ) (228.9 ) (635.9 ) Accumulated other comprehensive loss 796.5 56.0 852.5 735.1 51.4 786.5 Net balance sheet impact $ 356.8 $ (179.1 ) $ 177.7 $ 327.7 $ (177.6 ) $ 150.1 At December 31, 2018 and 2017 , the benefit obligation of non-qualified pension plans was $5.9 million and $5.8 million , respectively, and was included in the above pension benefit obligation. There were no plan assets for these non-qualified pension plans. Benefit payments for the non-qualified pension plans are expected to be as follows: 2019 — $0.5 million ; 2020 — $0.9 million ; 2021 — $0.5 million ; 2022 — $0.4 million ; and 2023 — $0.3 million . Benefit payments for the qualified plans are projected to be as follows: 2019 — $140.5 million ; 2020 — $140.3 million ; 2021 — $139.4 million ; 2022 — $138.0 million ; and 2023 — $135.2 million . December 31, 2018 2017 ($ in millions) Projected benefit obligation $ 2,667.8 $ 2,883.3 Accumulated benefit obligation 2,641.3 2,851.0 Fair value of plan assets 1,993.0 2,246.9 Years Ended December 31, 2018 2017 2016 Components of Net Periodic Benefit (Income) Costs ($ in millions) Service cost $ 11.1 $ 9.4 $ 9.0 Interest cost 86.3 86.6 87.7 Expected return on plans’ assets (146.5 ) (149.4 ) (154.5 ) Amortization of prior service cost 0.1 2.2 — Recognized actuarial loss 34.5 24.8 20.7 Net periodic benefit (income) costs $ (14.5 ) $ (26.4 ) $ (37.1 ) Included in Other Comprehensive Loss (Pretax) Liability adjustment $ 100.6 $ 26.9 $ 66.1 Amortization of prior service costs and actuarial losses (34.6 ) (27.0 ) (20.7 ) In March 2017, the FASB issued ASU 2017-07, “Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” (ASU 2017-07) which amends ASC 715 “Compensation—Retirement Benefits.” The adoption of ASU 2017-07 resulted in a change in our net periodic benefit (income) costs within operating income, which was offset by a corresponding change in non-operating pension income to reflect the impact of presenting the interest cost, expected return on plan assets, amortization of prior service cost and net actuarial loss components of net periodic benefit (income) costs outside of operating income. We adopted this update on January 1, 2018 using the retrospective method. For the years ended December 31, 2017 and 2016 , the adoption of ASU 2017-07 resulted in a reclassification of $15.3 million and $20.8 million , respectively, from cost of goods sold and $19.1 million and $24.0 million , respectively, from selling and administration to non-operating pension income reflecting the aforementioned reclassification on our consolidated statements of operations. The service cost component of net periodic benefit (income) costs continues to be included in the same income statement line item as other employee compensation costs arising from services rendered during the period. The service cost component of net periodic benefit (income) cost related to the employees of the operating segments are allocated to the operating segments based on their respective estimated census data. Pension Plan Assumptions Certain actuarial assumptions, such as discount rate and long-term rate of return on plan assets, have a significant effect on the amounts reported for net periodic benefit cost and accrued benefit obligation amounts. We use a measurement date of December 31 for our pension plans. U.S. Pension Benefits Foreign Pension Benefits Weighted-Average Assumptions 2018 2017 2016 2018 2017 2016 Discount rate—periodic benefit cost 3.6 % (1) 4.1 % 4.4 % 2.2 % 2.3 % 2.7 % Expected return on assets 7.75 % 7.75 % 7.75 % 5.2 % 5.6 % 6.0 % Rate of compensation increase 3.0 % 3.0 % 3.0 % 2.9 % 3.0 % 3.0 % Discount rate—benefit obligation 4.2 % 3.6 % 4.1 % 2.2 % 2.2 % 2.3 % (1) The discount rate—periodic benefit cost for our domestic qualified pension plan is comprised of the discount rate used to determine interest costs of 3.2% and the discount rate used to determine service costs of 3.7% . The discount rate is based on a hypothetical yield curve represented by a series of annualized individual zero-coupon bond spot rates for maturities ranging from one-half to thirty years. The bonds used in the yield curve must have a rating of AA or better per Standard & Poor’s, be non-callable, and have at least $250 million par outstanding. The yield curve is then applied to the projected benefit payments from the plan. Based on these bonds and the projected benefit payment streams, the single rate that produces the same yield as the matching bond portfolio is used as the discount rate. The long-term expected rate of return on plan assets represents an estimate of the long-term rate of returns on the investment portfolio consisting of equities, fixed income and alternative investments. We use long-term historical actual return information, the allocation mix of investments that comprise plan assets, and forecast estimates of long-term investment returns, including inflation rates, by reference to external sources. The historic rates of return on plan assets have been 6.3% for the last 5 years, 9.2% for the last 10 years and 8.8% for the last 15 years. The following rates of return by asset class were considered in setting the long-term rate of return assumption: U.S. equities 9% to 13% Non-U.S. equities 6% to 11% Fixed income/cash 5% to 9% Alternative investments 5% to 15% Absolute return strategies 8% to 12% Plan Assets Our pension plan asset allocations at December 31, 2018 and 2017 by asset class were as follows: Percentage of Plan Assets Asset Class 2018 2017 U.S. equities 12 % 19 % Non-U.S. equities 15 % 17 % Fixed income/cash 32 % 24 % Alternative investments 24 % 21 % Absolute return strategies 17 % 19 % Total 100 % 100 % The Alternative Investments asset class includes hedge funds, real estate and private equity investments. The Alternative Investments class is intended to help diversify risk and increase returns by utilizing a broader group of assets. Absolute Return Strategies further diversify the plan’s assets through the use of asset allocations that seek to provide a targeted rate of return over inflation. The investment managers allocate funds within asset classes that they consider to be undervalued in an effort to preserve gains in overvalued asset classes and to find opportunities in undervalued asset classes. A master trust was established by our pension plan to accumulate funds required to meet benefit payments of our plan and is administered solely in the interest of our plan’s participants and their beneficiaries. The master trust’s investment horizon is long term. Its assets are managed by professional investment managers or invested in professionally managed investment vehicles. Our pension plan maintains a portfolio of assets designed to achieve an appropriate risk adjusted return. The portfolio of assets is also structured to manage risk by diversifying assets across asset classes whose return patterns are not highly correlated, investing in passively and actively managed strategies and in value and growth styles, and by periodic rebalancing of asset classes, strategies and investment styles to objectively set targets. As of December 31, 2018 , the following target allocation and ranges have been set for each asset class: Asset Class Target Allocation Target Range U.S. equities (1) 20 % 15-31 Non-U.S. equities (1) 16 % 2-32 Fixed income/cash (1) 43 % 21-75 Alternative investments 4 % 0-29 Absolute return strategies 17 % 10-30 (1) The target allocation for these asset classes include alternative investments, primarily hedge funds, based on the underlying investments in each hedge fund. Determining which hierarchical level an asset or liability falls within requires significant judgment. The following table summarizes our domestic and foreign defined benefit pension plan assets measured at fair value as of December 31, 2018 : Asset Class Investments Measured at Net Asset Value Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Equity securities ($ in millions) U.S. equities $ 111.5 $ 136.6 $ — $ — $ 248.1 Non-U.S. equities 255.8 44.5 0.9 — 301.2 Fixed income/cash Cash — 55.7 — — 55.7 Government treasuries 0.7 — 175.0 — 175.7 Corporate debt instruments 83.7 — 139.2 — 222.9 Asset-backed securities 153.6 — 17.6 — 171.2 Alternative investments Hedge fund of funds 440.8 — — — 440.8 Real estate funds 22.3 — — — 22.3 Private equity funds 7.6 — — — 7.6 Absolute return strategies 347.5 — — — 347.5 Total assets $ 1,423.5 $ 236.8 $ 332.7 $ — $ 1,993.0 The following table summarizes our domestic and foreign defined benefit pension plan assets measured at fair value as of December 31, 2017 : Asset Class Investments Measured at Net Asset Value Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Equity securities ($ in millions) U.S. equities $ 230.7 $ 203.7 $ — $ — $ 434.4 Non-U.S. equities 321.9 55.6 14.6 — 392.1 Fixed income/cash Cash — 41.9 — — 41.9 Government treasuries 0.7 — 151.2 — 151.9 Corporate debt instruments 80.9 — 115.1 — 196.0 Asset-backed securities 104.3 — 44.0 — 148.3 Alternative investments Hedge fund of funds 430.7 — — — 430.7 Real estate funds 21.8 — — — 21.8 Private equity funds 11.5 — — — 11.5 Absolute return strategies 418.3 — — — 418.3 Total assets $ 1,620.8 $ 301.2 $ 324.9 $ — $ 2,246.9 U.S. equities —This class included actively and passively managed equity investments in common stock and commingled funds comprised primarily of large-capitalization stocks with value, core and growth strategies. Non-U.S. equities —This class included actively managed equity investments in commingled funds comprised primarily of international large-capitalization stocks from both developed and emerging markets. Fixed income and cash— This class included commingled funds comprised of debt instruments issued by the U.S. and Canadian Treasuries, U.S. Agencies, corporate debt instruments, asset- and mortgage-backed securities and cash. Hedge fund of funds— This class included a hedge fund which invests in the following types of hedge funds: Event driven hedge funds— This class included hedge funds that invest in securities to capture excess returns that are driven by market or specific company events including activist investment philosophies and the arbitrage of equity and private and public debt securities. Market neutral hedge funds —This class included investments in U.S. and international equities and fixed income securities while maintaining a market neutral position in those markets. Other hedge funds —This class primarily included long-short equity strategies and a global macro fund which invested in fixed income, equity, currency, commodity and related derivative markets. Real estate funds —This class included several funds that invest primarily in U.S. commercial real estate. Private equity funds —This class included several private equity funds that invest primarily in infrastructure and U.S. power generation and transmission assets. Absolute return strategies —This class included multiple strategies which use asset allocations that seek to provide a targeted rate of return over inflation. The investment managers allocate funds within asset classes that they consider to be undervalued in an effort to preserve gains in overvalued asset classes and to find opportunities in undervalued asset classes. U.S. equities and non-U.S. equities are primarily valued at the net asset value provided by the independent administrator or custodian of the commingled fund. The net asset value is based on the value of the underlying equities, which are traded on an active market. U.S. equities are also valued at the closing price reported in an active market on which the individual securities are traded. A portion of our fixed income investments are valued at the net asset value provided by the independent administrator or custodian of the fund. The net asset value is based on the underlying assets, which are valued using inputs such as the closing price reported, if traded on an active market, values derived from comparable securities of issuers with similar credit ratings, or under a discounted cash flow approach that utilizes observable inputs, such as current yields of similar instruments, but includes adjustments for risks that may not be observable such as certain credit and liquidity risks. Alternative investments are valued at the net asset value as determined by the independent administrator or custodian of the fund. The net asset value is based on the underlying investments, which are valued using inputs such as quoted market prices of identical instruments, discounted future cash flows, independent appraisals and market-based comparable data. Absolute return strategies are commingled funds which reflect the fair value of our ownership interest in these funds. The investments in these commingled funds include some or all of the above asset classes and are primarily valued at net asset values based on the underlying investments, which are valued consistent with the methodologies described above for each asset class.

POSTRETIREMENT BENEFITS

POSTRETIREMENT BENEFITS	12 Months Ended
	Dec. 31, 2018
POSTRETIREMENT BENEFITS Disclosure [Abstract]
POSTRETIREMENT BENEFITS	NOTE 15 . POSTRETIREMENT BENEFITS We provide certain postretirement healthcare (medical) and life insurance benefits for eligible active and retired domestic employees. The healthcare plans are contributory with participants’ contributions adjusted annually based on medical rates of inflation and plan experience. We use a measurement date of December 31 for our postretirement plans. Other Postretirement Benefits Obligations and Funded Status Changes in the benefit obligation were as follows: December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total Change in Benefit Obligation ($ in millions) Benefit obligation at beginning of year $ 40.6 $ 10.2 $ 50.8 $ 43.6 $ 8.6 $ 52.2 Service cost 0.9 0.4 1.3 0.8 0.3 1.1 Interest cost 1.2 0.3 1.5 1.2 0.3 1.5 Actuarial (gain) loss (2.0 ) (0.1 ) (2.1 ) (0.6 ) 1.0 0.4 Benefits paid (3.2 ) (0.4 ) (3.6 ) (4.4 ) (0.3 ) (4.7 ) Foreign currency translation adjustments — (0.9 ) (0.9 ) — 0.3 0.3 Benefit obligation at end of year $ 37.5 $ 9.5 $ 47.0 $ 40.6 $ 10.2 $ 50.8 December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total ($ in millions) Funded status $ (37.5 ) $ (9.5 ) $ (47.0 ) $ (40.6 ) $ (10.2 ) $ (50.8 ) Under ASC 715, we recorded a $1.6 million after-tax benefit ( $2.1 million pretax) to shareholders’ equity as of December 31, 2018 for our other postretirement plans. In 2017 , we recorded an after-tax charge of $0.3 million ( $0.4 million pretax) to shareholders’ equity as of December 31, 2017 for our other postretirement plans. Amounts recognized in the consolidated balance sheets consisted of: December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total ($ in millions) Accrued benefit in current liabilities $ (3.6 ) $ (0.3 ) $ (3.9 ) $ (4.0 ) $ (0.3 ) $ (4.3 ) Accrued benefit in noncurrent liabilities (33.9 ) (9.2 ) (43.1 ) (36.6 ) (9.9 ) (46.5 ) Accumulated other comprehensive loss 20.1 1.0 21.1 24.7 0.9 25.6 Net balance sheet impact $ (17.4 ) $ (8.5 ) $ (25.9 ) $ (15.9 ) $ (9.3 ) $ (25.2 ) Years Ended December 31, 2018 2017 2016 Components of Net Periodic Benefit Cost ($ in millions) Service cost $ 1.3 $ 1.1 $ 1.2 Interest cost 1.5 1.5 1.6 Amortization of prior service cost — (2.2 ) (2.6 ) Recognized actuarial loss 2.4 2.1 2.3 Net periodic benefit cost $ 5.2 $ 2.5 $ 2.5 Included in Other Comprehensive Loss (Pretax) Liability adjustment $ (2.1 ) $ 0.4 $ (5.1 ) Amortization of prior service costs and actuarial losses (2.4 ) 0.1 0.3 The service cost component of net periodic postretirement benefit cost related to the employees of the operating segments are allocated to the operating segments based on their respective estimated census data. Other Postretirement Benefits Plan Assumptions Certain actuarial assumptions, such as discount rate, have a significant effect on the amounts reported for net periodic benefit cost and accrued benefit obligation amounts. December 31, Weighted-Average Assumptions 2018 2017 2016 Discount rate—periodic benefit cost 3.5 % 3.8 % 4.1 % Discount rate—benefit obligation 4.1 % 3.5 % 3.8 % The discount rate is based on a hypothetical yield curve represented by a series of annualized individual zero-coupon bond spot rates for maturities ranging from one-half to thirty years. The bonds used in the yield curve must have a rating of AA or better per Standard & Poor’s, be non-callable, and have at least $250 million par outstanding. The yield curve is then applied to the projected benefit payments from the plan. Based on these bonds and the projected benefit payment streams, the single rate that produces the same yield as the matching bond portfolio is used as the discount rate. We review external data and our own internal trends for healthcare costs to determine the healthcare cost for the post retirement benefit obligation. The assumed healthcare cost trend rates for pre-65 retirees were as follows: December 31, 2018 2017 Healthcare cost trend rate assumed for next year 7.5 % 8.0 % Rate that the cost trend rate gradually declines to 4.5 % 4.5 % Year that the rate reaches the ultimate rate 2024 2024 For post-65 retirees, we provide a fixed dollar benefit, which is not subject to escalation. We expect to make payments of approximately $4 million for each of the next five years under the provisions of our other postretirement benefit plans.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE 16 . INCOME TAXES Years ended December 31, 2018 2017 2016 Components of Income (Loss) Before Taxes ($ in millions) Domestic $ 288.0 $ 53.3 $ (23.3 ) Foreign 149.3 63.9 (10.9 ) Income (loss) before taxes $ 437.3 $ 117.2 $ (34.2 ) Components of Income Tax Provision (Benefit) Current expense (benefit): Federal $ 21.7 $ (4.0 ) $ (11.6 ) State 5.1 3.0 0.9 Foreign 48.0 24.1 15.7 74.8 23.1 5.0 Deferred expense (benefit): Federal 27.0 (549.6 ) (10.1 ) State (0.8 ) 14.6 (5.1 ) Foreign 8.4 79.6 (20.1 ) 34.6 (455.4 ) (35.3 ) Income tax provision (benefit) $ 109.4 $ (432.3 ) $ (30.3 ) The following table accounts for the difference between the actual tax provision and the amounts obtained by applying the statutory U.S. federal income tax rate to the income (loss) before taxes. Years ended December 31, Effective Tax Rate Reconciliation (Percent) 2018 2017 2016 Statutory federal tax rate 21.0 % 35.0 % 35.0 % State income taxes, net 2.0 (1.2 ) 8.0 Foreign rate differential 1.8 (7.7 ) (25.1 ) U.S. tax on foreign earnings 1.1 (70.8 ) 24.4 Salt depletion (2.4 ) (16.1 ) 45.4 Change in valuation allowance 3.8 76.0 (0.7 ) Remeasurement of U.S. state deferred taxes (0.6 ) 10.2 9.4 Change in tax contingencies (0.7 ) (7.7 ) (9.7 ) U.S. Tax Cuts and Jobs Act (0.8 ) (373.5 ) — Share-based payments — (5.7 ) — Dividends paid to Contributing Employee Ownership Plan (0.1 ) (0.6 ) 2.8 Return to provision (0.1 ) (0.6 ) 5.3 U.S. Federal tax credits (0.4 ) (4.2 ) 0.6 Other, net 0.4 (2.0 ) (6.8 ) Effective tax rate 25.0 % (368.9 )% 88.6 % The effective tax rate for 2018 included benefits associated with the 2017 Tax Act, stock-based compensation, changes in tax contingencies, a foreign dividend payment, changes associated with prior year tax positions and the remeasurement of deferred taxes due to a decrease in our state effective tax rates. The effective tax rate also included expenses associated with a net increase in the valuation allowance related to deferred tax assets in foreign jurisdictions and the remeasurement of deferred taxes due to changes in our foreign tax rates. These factors resulted in a net $2.9 million tax benefit, of which $3.8 million related to the increase of the 2017 Tax Act benefit. After giving consideration to these items, the effective tax rate for 2018 of 25.7% was higher than the 21% U.S. federal statutory rate primarily due to state and foreign income taxes, foreign income inclusions and a net increase in the valuation allowance related to current year losses in foreign jurisdictions, partially offset by favorable permanent salt depletion deductions. The effective tax rate for 2017 included benefits associated with the 2017 Tax Act, an agreement with the Internal Revenue Service (IRS) on prior period tax examinations, stock based compensation, U.S. federal tax credits, changes to prior year tax positions and a reduction to the deferred tax liability on unremitted foreign earnings. The effective tax rate also included an expense associated with a net increase in the valuation allowance, primarily related to foreign net operating losses and remeasurement of deferred taxes due to an increase in our state effective tax rates. These factors resulted in a net $452.3 million tax benefit, of which $437.9 million was a provisional benefit from the 2017 Tax Act. After giving consideration to these items, the effective tax rate for 2017 of 17.1% was lower than the 35% U.S. federal statutory rate, primarily due to favorable permanent salt depletion deductions. The effective tax rate for 2016 included benefits associated with return to provision adjustments, primarily related to salt depletion and non-deductible acquisition costs, and the remeasurement of deferred taxes due to a decrease in our state effective tax rates. The effective tax rate also included an expense associated with a change in prior year uncertain tax positions. These factors resulted in a net $3.9 million tax benefit. After giving consideration to these items, the effective tax rate for 2016 of 77.2% was higher than the 35% U.S. federal statutory rate, primarily due to favorable permanent salt depletion deductions in combination with a pretax loss. The 2017 Tax Act was enacted on December 22, 2017 and included a broad range of provisions impacting the taxation of businesses. Included within the provisions, the 2017 Tax Act reduced the U.S. federal corporate tax rate from 35% to 21% , required companies to pay a one-time transition tax on unremitted earnings of foreign subsidiaries that were previously tax deferred and transitioned the U.S. from a worldwide tax system to a modified territorial tax system. The SEC Staff issued SAB 118, which provided guidance on accounting for the tax effects of the 2017 Tax Act. SAB 118 provided a measurement period of up to one year from the 2017 Tax Act’s enactment date for companies to complete the accounting under ASC 740 “Income Taxes” (ASC 740). In accordance with SAB 118, to the extent that a company’s accounting for certain income tax effects of the 2017 Tax Act was incomplete but it was able to determine a reasonable estimate, it should have recorded a provisional estimate in the financial statements. If a company could not determine a provisional estimate to be included in the financial statements, it should have continued to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the 2017 Tax Act. At December 31, 2018, we have completed our accounting for the tax effects of the 2017 Tax Act and accounted for updates to estimates of significant items including: (1) the effects on our existing deferred tax balances, (2) the remeasurement of deferred taxes on foreign unremitted earnings and (3) the one-time transition tax. In connection with our initial analysis of the 2017 Tax Act, we recognized a provisional deferred tax benefit of $437.9 million at December 31, 2017. This benefit included: (1) a provisional $315.8 million deferred tax benefit to reflect the reduction of the U.S. corporate tax rate from 35% to 21% and (2) a provisional $122.1 million deferred tax benefit to reflect an estimated reduction of $162.6 million in our deferred tax liability on unremitted foreign earnings partially offset by an estimate of the one-time transition tax of $40.5 million . We utilized existing U.S. federal net operating loss carryforwards and foreign tax credits to fully offset the cash tax impact of the one-time transition tax liability. For the year ended December 31, 2018, we decreased the deferred tax benefit by $0.1 million as a result of additional guidance issued by the IRS. For the year ended December 31, 2018, we increased the deferred tax benefit by $3.9 million as a result of filing the 2017 U.S. and foreign tax returns. A provision of the 2017 Tax Act established a minimum tax on certain foreign earnings (i.e. global intangible low-taxed income or GILTI). We have completed our analysis of the GILTI tax rules and have made the accounting policy election to treat the taxes due from GILTI as a period expense when incurred. December 31, Components of Deferred Tax Assets and Liabilities 2018 2017 Deferred tax assets: ($ in millions) Pension and postretirement benefits $ 156.8 $ 147.3 Environmental reserves 31.9 33.2 Asset retirement obligations 15.5 14.0 Accrued liabilities 37.0 37.6 Tax credits 19.5 37.1 Net operating losses 50.2 53.3 Capital loss carryforward 2.0 2.1 Other miscellaneous items 23.9 11.2 Total deferred tax assets 336.8 335.8 Valuation allowance (147.4 ) (121.4 ) Net deferred tax assets 189.4 214.4 Deferred tax liabilities: Property, plant and equipment 541.8 550.3 Intangible amortization 61.6 67.3 Inventory and prepaids 8.3 1.0 Partnerships 65.2 67.5 Taxes on unremitted earnings 5.1 3.1 Total deferred tax liabilities 682.0 689.2 Net deferred tax liability $ (492.6 ) $ (474.8 ) Realization of the net deferred tax assets, irrespective of indefinite-lived deferred tax liabilities, is dependent on future reversals of existing taxable temporary differences and adequate future taxable income, exclusive of reversing temporary differences and carryforwards. Although realization is not assured, we believe that it is more likely than not that the net deferred tax assets will be realized. At December 31, 2018 , we had a U.S. net operating loss carryforward (NOL) of approximately $0.5 million (representing $0.1 million of deferred tax assets) that will expire after 2019, if not utilized. At December 31, 2018 , we had deferred state tax benefits of $12.2 million relating to state NOLs, which are available to offset future state taxable income through 2037. At December 31, 2018 , we had deferred state tax benefits of $18.1 million relating to state tax credits, which are available to offset future state tax liabilities through 2033. At December 31, 2018 , we had a capital loss carryforward of $8.3 million (representing $2.0 million of deferred tax assets) which is available to offset future consolidated capital gains that will expire in years 2019 through 2022, if not utilized. At December 31, 2018 , we had foreign tax credits of $5.0 million , which are available to offset certain federal tax liabilities through 2028. At December 31, 2018 , we had NOLs of approximately $225.8 million (representing $38.0 million of deferred tax assets) in various foreign jurisdictions. Of these, $44.8 million (representing $11.0 million of deferred tax assets) expire in various years from 2020 to 2028. The remaining $181.0 million (representing $27.0 million of deferred tax assets) do not expire. As of December 31, 2018 , we had recorded a valuation allowance of $147.4 million , compared to $121.4 million as of December 31, 2017 . The increase of $26.0 million is primarily due to the recent history of cumulative losses within foreign jurisdictions and projections of future taxable income insufficient to overcome the loss history. We continue to have net deferred tax assets in several jurisdictions which we expect to realize, assuming sufficient taxable income can be generated to utilize these deferred tax benefits, which is based on certain estimates and assumptions. If these estimates and related assumptions change in the future, we may be required to reduce the value of the deferred tax assets resulting in additional tax expense. The activity of our deferred income tax valuation allowance was as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 121.4 $ 29.0 Increases to valuation allowances 31.9 94.5 U.S. Tax Cuts and Jobs Act — 2.2 Decreases to valuation allowances (0.9 ) (5.0 ) Currency translation adjustment (5.0 ) 0.7 Ending balance $ 147.4 $ 121.4 As of December 31, 2018 , we had $33.8 million of gross unrecognized tax benefits, which would have a net $33.0 million impact on the effective tax rate, if recognized. As of December 31, 2017 , we had $36.3 million of gross unrecognized tax benefits, which would have a net $35.5 million impact on the effective tax rate, if recognized. The change for 2018 primarily relates to additional gross unrecognized benefits for current and prior year tax positions, as well as decreases for prior year tax positions. The change for 2017 primarily relates to additional gross unrecognized benefits for current and prior year tax positions, as well as decreases for prior year tax positions. The amounts of unrecognized tax benefits were as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 36.3 $ 38.4 Increase for current year tax positions 2.1 2.9 Increase for prior year tax positions 0.3 5.4 Reductions due to statute of limitations — (0.1 ) Decrease for prior year tax positions (4.9 ) (9.2 ) Decrease due to tax settlements — (1.1 ) Ending balance $ 33.8 $ 36.3 In May 2017, we reached an agreement in principle with the IRS regarding their examination of our U.S. income tax returns for 2008 and 2010 to 2012. The settlement resulted in a reduction of income tax expense of $9.5 million related primarily to favorable adjustments in uncertain tax positions for prior tax years. We recognize interest and penalty expense related to unrecognized tax positions as a component of the income tax provision. As of December 31, 2018 and 2017 , interest and penalties accrued were $1.6 million and $1.2 million , respectively. For 2018 , 2017 and 2016 , we recorded expense (benefit) related to interest and penalties of $0.4 million , $(1.8) million and $(0.4) million , respectively. As of December 31, 2018 , we believe it is reasonably possible that our total amount of unrecognized tax benefits will decrease by approximately $7.2 million over the next twelve months. The anticipated reduction primarily relates to settlements with tax authorities and the expiration of federal, state and foreign statutes of limitation. We operate globally and file income tax returns in numerous jurisdictions. Our tax returns are subject to examination by various federal, state and local tax authorities. None of our U.S. federal income tax returns are currently under examination by the IRS. In connection with the October 5, 2015 acquisition of DowDuPont’s U.S. Chlor Alkali and Vinyl, Global Chlorinated Organics and Global Epoxy businesses, the prior owner of the businesses retained liabilities relating to taxes to the extent arising prior to October 5, 2015. We believe we have adequately provided for all tax positions; however, amounts asserted by taxing authorities could be greater than our accrued position. For our primary tax jurisdictions, the tax years that remain subject to examination are as follows: Tax Years U.S. federal income tax 2013 - 2017 U.S. state income tax 2006 - 2017 Canadian federal income tax 2012 - 2017 Brazil 2014 - 2017 Germany 2015 - 2017 China 2014 - 2017 The Netherlands 2014 - 2017

ACCRUED LIABILITIES

ACCRUED LIABILITIES	12 Months Ended
	Dec. 31, 2018
Accrued Liabilities, Current [Abstract]
ACCRUED LIABILITIES	NOTE 17 . ACCRUED LIABILITIES Included in accrued liabilities were the following: December 31, 2018 2017 ($ in millions) Accrued compensation and payroll taxes $ 100.0 $ 80.6 Tax-related accruals 23.1 21.7 Accrued interest 48.9 37.4 Legal and professional costs 54.4 34.8 Accrued employee benefits 25.3 21.7 Environmental (current portion only) 17.0 20.0 Asset retirement obligation (current portion only) 10.6 10.5 Restructuring reserves (current portion only) 7.3 3.3 Other 46.7 44.4 Accrued liabilities $ 333.3 $ 274.4

CONTRIBUTING EMPLOYEE OWNERSHIP

CONTRIBUTING EMPLOYEE OWNERSHIP PLAN	12 Months Ended
	Dec. 31, 2018
Defined Contribution Plan [Abstract]
CONTRIBUTING EMPLOYEE OWNERSHIP PLAN	NOTE 18 . CONTRIBUTING EMPLOYEE OWNERSHIP PLAN The Contributing Employee Ownership Plan (CEOP) is a defined contribution plan available to essentially all domestic employees. We provide a contribution to an individual retirement contribution account maintained with the CEOP equal to an amount of between 5.0% and 7.5% of the employee’s eligible compensation. The defined contribution plan expense was $28.6 million , $29.0 million and $28.2 million for 2018 , 2017 and 2016 , respectively. Company matching contributions are invested in the same investment allocation as the employee’s contribution. Our matching contributions for eligible employees amounted to $14.9 million , $11.5 million and $11.2 million in 2018 , 2017 and 2016 , respectively. Employees generally become vested in the value of the contributions we make to the CEOP according to a schedule based on service. After two years of service, participants are 25% vested. They vest in increments of 25% for each additional year and after five years of service, they are 100% vested in the value of the contributions that we have made to their accounts. Employees may transfer any or all of the value of the investments, including Olin common stock, to any one or combination of investments available in the CEOP. Employees may transfer balances daily and may elect to transfer any percentage of the balance in the fund from which the transfer is made. However, when transferring out of a fund, employees are prohibited from trading out of the fund to which the transfer was made for seven calendar days. This limitation does not apply to trades into the money market fund or the Olin Common Stock Fund.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	NOTE 19 . STOCK-BASED COMPENSATION Stock-based compensation expense was allocated to the operating segments for the portion related to employees whose compensation would be included in cost of goods sold with the remainder recognized in corporate/other. There were no significant capitalized stock-based compensation costs. Stock-based compensation granted includes stock options, performance stock awards, restricted stock awards and deferred directors’ compensation. Stock-based compensation expense was as follows: Years ended December 31, 2018 2017 2016 ($ in millions) Stock-based compensation $ 19.3 $ 18.7 $ 11.2 Mark-to-market adjustments (10.1 ) 4.5 3.0 Total expense $ 9.2 $ 23.2 $ 14.2 Stock Plans Under the stock option and long-term incentive plans, options may be granted to purchase shares of our common stock at an exercise price not less than fair market value at the date of grant, and are exercisable for a period not exceeding ten years from that date. Stock options, restricted stock and performance shares typically vest over three years. We issue shares to settle stock options, restricted stock and share-based performance awards. In 2018 , 2017 and 2016 , long-term incentive awards included stock options, performance share awards and restricted stock. The stock option exercise price was set at the fair market value of common stock on the date of the grant, and the options have a ten -year term. Stock option transactions were as follows: Exercisable Shares Option Price Weighted-Average Option Price Options Weighted-Average Exercise Price Outstanding at January 1, 2018 5,342,526 $13.14-31.90 $ 22.72 2,603,962 $ 21.78 Granted 927,000 32.94-32.94 32.94 Exercised (204,064 ) 13.14-29.75 17.68 Canceled (201,246 ) 13.14-32.94 25.92 Outstanding at December 31, 2018 5,864,216 $13.14-32.94 $ 24.40 3,571,732 $ 22.27 At December 31, 2018 , the average exercise period for all outstanding and exercisable options was 79 months and 66 months, respectively. At December 31, 2018 , the aggregate intrinsic value (the difference between the exercise price and market value) for outstanding options was $9.5 million and exercisable options was $6.4 million . The total intrinsic value of options exercised during the years ended December 31, 2018 , 2017 and 2016 was $2.9 million , $26.5 million and $2.1 million , respectively. The total unrecognized compensation cost related to unvested stock options at December 31, 2018 was $9.8 million and was expected to be recognized over a weighted-average period of 1.3 years. The following table provides certain information with respect to stock options exercisable at December 31, 2018 : Range of Options Exercisable Weighted-Average Exercise Price Options Outstanding Weighted-Average Exercise Price Under $20.00 1,129,630 $ 14.19 1,579,848 $ 13.89 $20.00 - $26.00 1,290,236 23.77 1,290,236 23.77 Over $26.00 1,151,866 28.49 2,994,132 30.22 3,571,732 5,864,216 At December 31, 2018 , common shares reserved for issuance and available for grant or purchase under the following plans consisted of: Number of Shares Stock Option Plans Reserved for Issuance Available for Grant or Purchase (1) 2000 long term incentive plan 44,130 — 2003 long term incentive plan 215,584 — 2006 long term incentive plan 278,270 — 2009 long term incentive plan 1,873,421 — 2014 long term incentive plan 2,098,802 — 2016 long term incentive plan 2,326,334 — 2018 long term incentive plan 9,263,665 9,252,665 Total under stock option plans 16,100,206 9,252,665 Number of Shares Stock Purchase Plans Reserved for Issuance Available for Grant or Purchase 1997 stock plan for non-employee directors 536,295 375,245 (1) All available to be issued as stock options, but includes a sub-limit for all types of stock awards of 1,989,000 shares. Under the stock purchase plans, our non-employee directors may defer certain elements of their compensation into shares of our common stock based on fair market value of the shares at the time of deferral. Non-employee directors annually receive stock grants as a portion of their director compensation. Of the shares reserved under the stock purchase plans at December 31, 2018 , 161,049 shares were committed. Performance share awards are denominated in shares of our stock and are paid half in cash and half in stock. Payouts for performance share awards granted prior to December 31, 2016 are based on Olin’s average annual return on capital over a three -year performance cycle in relation to the average annual return on capital over the same period among a portfolio of public companies which are selected in concert with outside compensation consultants. Payouts for performance share awards granted during 2017 and 2018 are based on two criteria: (1) 50% of the award is based on Olin’s total shareholder returns over the applicable three -year performance cycle in relation to the total shareholder return over the same period among a portfolio of public companies which are selected in concert with outside compensation consultants and (2) 50% of the award is based on Olin’s net income over the applicable three -year performance cycle in relation to the net income goal for such period as set by the compensation committee of Olin’s board of directors. The expense associated with performance shares is recorded based on our estimate of our performance relative to the respective target. If an employee leaves the company before the end of the performance cycle, the performance shares may be prorated based on the number of months of the performance cycle worked and are settled in cash instead of half in cash and half in stock when the three-year performance cycle is completed. Performance share transactions were as follows: To Settle in Cash To Settle in Shares Shares Weighted-Average Fair Value per Share Shares Weighted-Average Fair Value per Share Outstanding at January 1, 2018 650,689 $ 35.62 480,200 $ 19.81 Granted 81,626 32.67 88,500 33.03 Paid/Issued (77,262 ) 35.62 (34,500 ) 27.40 Converted from shares to cash 29,375 17.88 (29,375 ) 17.88 Canceled (14,125 ) 34.68 (14,125 ) 26.51 Outstanding at December 31, 2018 670,303 $ 19.89 490,700 $ 21.58 Total vested at December 31, 2018 564,686 $ 19.89 385,083 $ 18.95 The summary of the status of our unvested performance shares to be settled in cash were as follows: Shares Weighted-Average Fair Value per Share Unvested at January 1, 2018 202,017 $ 35.62 Granted 81,626 32.67 Vested (163,901 ) 19.89 Canceled (14,125 ) 34.68 Unvested at December 31, 2018 105,617 $ 19.89 At December 31, 2018 , the liability recorded for performance shares to be settled in cash totaled $11.2 million . The total unrecognized compensation cost related to unvested performance shares at December 31, 2018 was $5.4 million and was expected to be recognized over a weighted-average period of 1.3 years.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	NOTE 20 . SHAREHOLDERS’ EQUITY On April 26, 2018, our board of directors authorized a share repurchase program for the purchase of shares of common stock at an aggregate price of up to $500.0 million . This program will terminate upon the purchase of $500.0 million of our common stock. For the year ended December 31, 2018 , 2.1 million shares were repurchased and retired at a cost of $50.0 million . As of December 31, 2018 , $450.0 million of common stock remained authorized to be repurchased. During 2018 , 2017 and 2016 , we issued 0.2 million , 1.7 million and 0.3 million shares, respectively, with a total value of $3.4 million , $32.4 million and $4.1 million , respectively, representing stock options exercised. We have registered an undetermined amount of securities with the SEC, so that, from time-to-time, we may issue debt securities, preferred stock and/or common stock and associated warrants in the public market under that registration statement. In February 2018, the FASB issued ASU 2018-02, “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” (ASU 2018-02) which amends ASC 220 “Income Statement—Reporting Comprehensive Income.” This update allows a reclassification from accumulated other comprehensive loss to retained earnings for the stranded tax effects resulting from the 2017 Tax Act during each fiscal year or quarter in which the effect of the lower tax rate is recorded. We adopted this update in March 2018 and reclassified $85.9 million related to the deferred gain resulting from the 2017 Tax Act from accumulated other comprehensive loss to retained earnings. The following table represents the activity included in accumulated other comprehensive loss: Foreign Currency Translation Adjustment (net of taxes) Unrealized (Losses) Gains on Derivative Contracts (net of taxes) Pension and Other Postretirement Benefits (net of taxes) Accumulated Other Comprehensive Loss ($ in millions) Balance at January 1, 2016 $ (12.1 ) $ (6.9 ) $ (473.5 ) $ (492.5 ) Unrealized (losses) gains (22.4 ) 26.3 (61.0 ) (57.1 ) Reclassification adjustments of losses into income — 5.8 20.4 26.2 Tax benefit (provision) 10.4 (12.4 ) 15.4 13.4 Net change (12.0 ) 19.7 (25.2 ) (17.5 ) Balance at December 31, 2016 (24.1 ) 12.8 (498.7 ) (510.0 ) Unrealized gains (losses) 55.6 1.9 (27.3 ) 30.2 Reclassification adjustments of (gains) losses into income — (4.6 ) 26.9 22.3 Tax (provision) benefit (23.9 ) 1.0 (4.2 ) (27.1 ) Net change 31.7 (1.7 ) (4.6 ) 25.4 Balance at December 31, 2017 7.6 11.1 (503.3 ) (484.6 ) Unrealized losses (22.2 ) (1.1 ) (98.5 ) (121.8 ) Reclassification adjustments of (gains) losses into income — (14.3 ) 37.0 22.7 Tax benefit (provision) — 3.7 14.9 18.6 Net change (22.2 ) (11.7 ) (46.6 ) (80.5 ) Income tax reclassification adjustment 15.3 2.4 (103.6 ) (85.9 ) Balance at December 31, 2018 $ 0.7 $ 1.8 $ (653.5 ) $ (651.0 ) Net income (loss) and cost of goods sold included reclassification adjustments for realized gains and losses on derivative contracts from accumulated other comprehensive loss. Net income (loss) and non-operating pension income included the amortization of prior service costs and actuarial losses from accumulated other comprehensive loss.

SEGMENT INFORMATION

SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
SEGMENT INFORMATION	NOTE 21 . SEGMENT INFORMATION We define segment results as income (loss) before interest expense, interest income, other operating income (expense), non-operating pension income and income taxes, and includes the operating results of non-consolidated affiliates. Consistent with the guidance in ASC 280 “Segment Reporting,” we have determined it is appropriate to include the operating results of non-consolidated affiliates in the relevant segment financial results. We have three operating segments: Chlor Alkali Products and Vinyls, Epoxy and Winchester. The three operating segments reflect the organization used by our management for purposes of allocating resources and assessing performance. Chlorine used in our Epoxy segment is transferred at cost from the Chlor Alkali Products and Vinyls segment. Sales and profits are recognized in the Chlor Alkali Products and Vinyls segment for all caustic soda generated and sold by Olin. Years ended December 31, 2018 2017 2016 Sales: ($ in millions) Chlor Alkali Products and Vinyls $ 3,986.7 $ 3,500.8 $ 2,999.3 Epoxy 2,303.1 2,086.4 1,822.0 Winchester 656.3 681.2 729.3 Total sales $ 6,946.1 $ 6,268.4 $ 5,550.6 Income (loss) before taxes: Chlor Alkali Products and Vinyls $ 637.1 $ 405.8 $ 224.9 Epoxy 52.8 (11.8 ) 15.4 Winchester 38.4 72.4 120.9 Corporate/Other: Environmental income (expense) 103.7 (8.5 ) (9.2 ) Other corporate and unallocated costs (158.3 ) (112.4 ) (91.4 ) Restructuring charges (21.9 ) (37.6 ) (112.9 ) Acquisition-related costs (1.0 ) (12.8 ) (48.8 ) Other operating income 6.4 3.3 10.6 Interest expense (243.2 ) (217.4 ) (191.9 ) Interest income 1.6 1.8 3.4 Non-operating pension income 21.7 34.4 44.8 Income (loss) before taxes $ 437.3 $ 117.2 $ (34.2 ) Earnings (losses) of non-consolidated affiliates: Chlor Alkali Products and Vinyls $ (19.7 ) $ 1.8 $ 1.7 Depreciation and amortization expense: Chlor Alkali Products and Vinyls $ 473.1 $ 432.2 $ 418.1 Epoxy 102.4 94.3 90.0 Winchester 20.0 19.5 18.5 Corporate/Other 5.9 12.9 6.9 Total depreciation and amortization expense $ 601.4 $ 558.9 $ 533.5 Capital spending: Chlor Alkali Products and Vinyls $ 259.9 $ 209.5 $ 195.1 Epoxy 36.3 37.9 45.4 Winchester 14.7 22.5 19.5 Corporate/Other 74.3 24.4 18.0 Total capital spending $ 385.2 $ 294.3 $ 278.0 Segment assets include only those assets which are directly identifiable to an operating segment. Assets of the corporate/other segment include primarily such items as cash and cash equivalents, deferred taxes and other assets. December 31, 2018 2017 Assets: ($ in millions) Chlor Alkali Products and Vinyls $ 6,837.2 $ 7,008.0 Epoxy 1,521.9 1,597.1 Winchester 399.9 425.2 Corporate/Other 238.4 188.0 Total assets $ 8,997.4 $ 9,218.3 Investments—affiliated companies (at equity): Chlor Alkali Products and Vinyls $ 8.8 $ 28.5 Long-lived assets are attributed to geographic areas based on asset location and sales are attributed to geographic areas based on customer location. December 31, 2018 2017 Long-lived assets: ($ in millions) United States $ 3,147.6 $ 3,211.9 Foreign 334.5 363.9 Total long-lived assets $ 3,482.1 $ 3,575.8 Year Ended December 31, 2018 Chlor Alkali Products and Vinyls Epoxy Winchester Total Sales: ($ in millions) United States $ 2,610.7 $ 742.7 $ 591.0 $ 3,944.4 Europe 181.8 991.1 11.0 1,183.9 Other foreign 1,194.2 569.3 54.3 1,817.8 Total Sales $ 3,986.7 $ 2,303.1 $ 656.3 $ 6,946.1 Year Ended December 31, 2017 Chlor Alkali Products and Vinyls Epoxy Winchester Total Sales: ($ in millions) United States $ 2,294.4 $ 646.5 $ 615.2 $ 3,556.1 Europe 130.1 940.8 11.6 1,082.5 Other foreign 1,076.3 499.1 54.4 1,629.8 Total Sales $ 3,500.8 $ 2,086.4 $ 681.2 $ 6,268.4 Year Ended December 31, 2016 Chlor Alkali Products and Vinyls Epoxy Winchester Total Sales: ($ in millions) United States $ 2,161.3 $ 532.4 $ 661.5 $ 3,355.2 Europe 121.3 787.6 15.0 923.9 Other foreign 716.7 502.0 52.8 1,271.5 Total Sales $ 2,999.3 $ 1,822.0 $ 729.3 $ 5,550.6 Years ended December 31, 2018 2017 2016 Sales: ($ in millions) Chlor Alkali Products and Vinyls Caustic soda $ 2,198.6 $ 1,904.3 $ 1,479.3 Chlorine, chlorine derivatives and other co-products 1,788.1 1,596.5 1,520.0 Total Chlor Alkali Products and Vinyls 3,986.7 3,500.8 2,999.3 Epoxy Aromatics and allylics 1,145.7 1,051.1 844.4 Epoxy resins 1,157.4 1,035.3 977.6 Total Epoxy 2,303.1 2,086.4 1,822.0 Winchester Commercial 427.6 471.0 559.7 Military and law enforcement 228.7 210.2 169.6 Total Winchester 656.3 681.2 729.3 Total Sales $ 6,946.1 $ 6,268.4 $ 5,550.6

ENVIRONMENTAL

ENVIRONMENTAL	12 Months Ended
	Dec. 31, 2018
Environmental Remediation Obligations [Abstract]
ENVIRONMENTAL	NOTE 22 . ENVIRONMENTAL As is common in our industry, we are subject to environmental laws and regulations related to the use, storage, handling, generation, transportation, emission, discharge, disposal and remediation of, and exposure to, hazardous and non-hazardous substances and wastes in all of the countries in which we do business. The establishment and implementation of national, state or provincial and local standards to regulate air, water and land quality affect substantially all of our manufacturing locations around the world. Laws providing for regulation of the manufacture, transportation, use and disposal of hazardous and toxic substances, and remediation of contaminated sites, have imposed additional regulatory requirements on industry, particularly the chemicals industry. In addition, implementation of environmental laws has required and will continue to require new capital expenditures and will increase plant operating costs. We employ waste minimization and pollution prevention programs at our manufacturing sites. In connection with the October 5, 2015 acquisition of DowDuPont’s U.S. Chlor Alkali and Vinyl, Global Chlorinated Organics and Global Epoxy businesses, the prior owner of the businesses retained liabilities relating to releases of hazardous materials and violations of environmental law to the extent arising prior to October 5, 2015. We are party to various government and private environmental actions associated with past manufacturing facilities and former waste disposal sites. Associated costs of investigatory and remedial activities are provided for in accordance with generally accepted accounting principles governing probability and the ability to reasonably estimate future costs. Our ability to estimate future costs depends on whether our investigatory and remedial activities are in preliminary or advanced stages. With respect to unasserted claims, we accrue liabilities for costs that, in our experience, we expect to incur to protect our interests against those unasserted claims. Our accrued liabilities for unasserted claims amounted to $8.6 million at December 31, 2018 . With respect to asserted claims, we accrue liabilities based on remedial investigation, feasibility study, remedial action and operation, maintenance and monitoring (OM&M) expenses that, in our experience, we expect to incur in connection with the asserted claims. Required site OM&M expenses are estimated and accrued in their entirety for required periods not exceeding 30 years, which reasonably approximates the typical duration of long-term site OM&M. Our liabilities for future environmental expenditures were as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 131.6 $ 137.3 Charges to income 7.3 10.3 Remedial and investigatory spending (13.0 ) (16.5 ) Foreign currency translation adjustments (0.3 ) 0.5 Ending balance $ 125.6 $ 131.6 At December 31, 2018 and 2017 , our consolidated balance sheets included environmental liabilities of $108.6 million and $111.6 million , respectively, which were classified as other noncurrent liabilities. Our environmental liability amounts do not take into account any discounting of future expenditures or any consideration of insurance recoveries or advances in technology. These liabilities are reassessed periodically to determine if environmental circumstances have changed and/or remediation efforts and our estimate of related costs have changed. As a result of these reassessments, future charges to income may be made for additional liabilities. Of the $125.6 million included on our consolidated balance sheet at December 31, 2018 for future environmental expenditures, we currently expect to utilize $68.9 million of the reserve for future environmental expenditures over the next 5 years, $14.1 million for expenditures 6 to 10 years in the future, and $42.6 million for expenditures beyond 10 years in the future. Our total estimated environmental liability at December 31, 2018 was attributable to 60 sites, 14 of which were United States Environmental Protection Agency National Priority List sites. Nine sites accounted for 79% of our environmental liability and, of the remaining 51 sites, no one site accounted for more than 3% of our environmental liability. At three of the nine sites, part of the site is subject to a remedial investigation and another part is in the long-term OM&M stage. At two of the nine sites, a remedial action plan is being developed for part of the site and another part a remedial design is being developed. At one of the nine sites, part of the site is subject to a remedial investigation and another part a remedial design is being developed. At one of the nine sites, a remedial action plan is being developed for part of the site and another part is in the long-term OM&M stage. The two remaining sites are in long-term OM&M. All nine sites are either associated with past manufacturing operations or former waste disposal sites. None of the nine largest sites represents more than 22% of the liabilities reserved on our consolidated balance sheet at December 31, 2018 for future environmental expenditures. Environmental provisions (credited) charged to income, which are included in cost of goods sold, were as follows: Years ended December 31, 2018 2017 2016 ($ in millions) Provisions charged to income $ 7.3 $ 10.3 $ 9.2 Insurance recoveries for costs incurred and expensed (111.0 ) (1.8 ) — Environmental (income) expense $ (103.7 ) $ 8.5 $ 9.2 During 2018, we settled certain disputes with respect to insurance coverage for costs at various environmental remediation sites for $121.0 million . Environmental (income) expense for the year ended December 31, 2018 include insurance recoveries for environmental costs incurred and expensed in prior periods of $111.0 million . The recoveries are reduced by estimated liabilities of $10.0 million associated with claims by subsequent owners of certain of the settled environmental sites. These charges relate primarily to remedial and investigatory activities associated with past manufacturing operations and former waste disposal sites and may be material to operating results in future years. Annual environmental-related cash outlays for site investigation and remediation are expected to range between approximately $15 million to $25 million over the next several years, which are expected to be charged against reserves recorded on our consolidated balance sheet. While we do not anticipate a material increase in the projected annual level of our environmental-related cash outlays for site investigation and remediation, there is always the possibility that such an increase may occur in the future in view of the uncertainties associated with environmental exposures. Environmental exposures are difficult to assess for numerous reasons, including the identification of new sites, developments at sites resulting from investigatory studies, advances in technology, changes in environmental laws and regulations and their application, changes in regulatory authorities, the scarcity of reliable data pertaining to identified sites, the difficulty in assessing the involvement and financial capability of other Potentially Responsible Parties (PRPs), our ability to obtain contributions from other parties and the lengthy time periods over which site remediation occurs. It is possible that some of these matters (the outcomes of which are subject to various uncertainties) may be resolved unfavorably to us, which could materially adversely affect our financial position or results of operations. At December 31, 2018 , we estimate that it is reasonably possible that we may have additional contingent environmental liabilities of $60 million in addition to the amounts for which we have already recorded as a reserve.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 23 . COMMITMENTS AND CONTINGENCIES The following table summarizes our contractual commitments under non-cancelable operating leases and purchase contracts as of December 31, 2018 : Operating Leases Purchase Commitments ($ in millions) 2019 $ 82.2 $ 678.5 2020 61.4 642.5 2021 44.2 727.7 2022 31.8 725.0 2023 23.2 725.0 Thereafter 102.6 4,424.9 Total commitments $ 345.4 $ 7,923.6 Our operating lease commitments are primarily for railroad cars, but also include logistics, manufacturing, office and storage facilities and equipment, information technology equipment and land. Virtually none of our lease agreements contain escalation clauses or step rent provisions. Total rent expense charged to operations amounted to $122.4 million , $118.5 million and $95.5 million in 2018 , 2017 and 2016 , respectively (sublease income is not significant). The above purchase commitments include raw material, capital expenditure and utility purchasing commitments utilized in our normal course of business for our projected needs. In connection with the Acquisition, certain additional agreements have been entered into with DowDuPont, including, long-term purchase agreements for raw materials. These agreements are maintained through long-term cost based contracts that provide us with a reliable supply of key raw materials. Key raw materials received from DowDuPont include ethylene, electricity, propylene and benzene. On February 27, 2017, we exercised the remaining option to obtain additional future ethylene at producer economics from DowDuPont. In connection with the exercise of this option, we also secured a long-term customer arrangement. As a result, an additional payment will be made to DowDuPont of between $440 million and $465 million on or about the fourth quarter of 2020. We are party to a dispute relating to a contract at our Plaquemine, LA facility. The other party to the contract has filed a demand for arbitration alleging, among other things, that Olin breached the related agreement and claiming damages in excess of the amount Olin believes it is obligated to pay under the contract. The arbitration hearing is scheduled for the fourth quarter 2019. Any additional losses related to this contract dispute are not currently estimable because of unresolved questions of fact and law but, if resolved unfavorably to Olin, they could have a material adverse effect on our financial position, cash flows or results of operations. We, and our subsidiaries, are defendants in various other legal actions (including proceedings based on alleged exposures to asbestos) incidental to our past and current business activities. At December 31, 2018 and 2017 , our consolidated balance sheets included liabilities for these legal actions of $15.6 million and $24.8 million , respectively. These liabilities do not include costs associated with legal representation and do not include $8.0 million of insurance recoveries included in receivables, net within the accompanying consolidated balance sheet as of December 31, 2017. Based on our analysis, and considering the inherent uncertainties associated with litigation, we do not believe that it is reasonably possible that these legal actions will materially and adversely affect our financial position, cash flows or results of operations. In connection with the October 5, 2015 acquisition of DowDuPont’s U.S. Chlor Alkali and Vinyl, Global Chlorinated Organics and Global Epoxy businesses, the prior owner of the businesses retained liabilities related to litigation to the extent arising prior to October 5, 2015. During the ordinary course of our business, contingencies arise resulting from an existing condition, situation or set of circumstances involving an uncertainty as to the realization of a possible gain contingency. In certain instances such as environmental projects, we are responsible for managing the cleanup and remediation of an environmental site. There exists the possibility of recovering a portion of these costs from other parties. We account for gain contingencies in accordance with the provisions of ASC 450 “Contingencies” and therefore do not record gain contingencies and recognize income until it is earned and realizable. For the year ended December 31, 2018, we recognized an insurance recovery of $8.0 million in other operating income for a second quarter 2017 business interruption at our Freeport, TX vinyl chloride monomer facility. For the year ended December 31, 2016, we recognized an insurance recovery of $11.0 million in other operating income for property damage and business interruption related to a 2008 chlor alkali facility incident.

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	NOTE 24 . DERIVATIVE FINANCIAL INSTRUMENTS We are exposed to market risk in the normal course of our business operations due to our purchases of certain commodities, our ongoing investing and financing activities and our operations that use foreign currencies. The risk of loss can be assessed from the perspective of adverse changes in fair values, cash flows and future earnings. We have established policies and procedures governing our management of market risks and the use of financial instruments to manage exposure to such risks. ASC 815 requires an entity to recognize all derivatives as either assets or liabilities in the consolidated balance sheets and measure those instruments at fair value. In accordance with ASC 815, we designate derivative contracts as cash flow hedges of forecasted purchases of commodities and forecasted interest payments related to variable-rate borrowings and designate certain interest rate swaps as fair value hedges of fixed-rate borrowings. We do not enter into any derivative instruments for trading or speculative purposes. Energy costs, including electricity and natural gas, and certain raw materials used in our production processes are subject to price volatility. Depending on market conditions, we may enter into futures contracts, forward contracts, commodity swaps and put and call option contracts in order to reduce the impact of commodity price fluctuations. The majority of our commodity derivatives expire within one year. We actively manage currency exposures that are associated with net monetary asset positions, currency purchases and sales commitments denominated in foreign currencies and foreign currency denominated assets and liabilities created in the normal course of business. We enter into forward sales and purchase contracts to manage currency to offset our net exposures, by currency, related to the foreign currency denominated monetary assets and liabilities of our operations. At December 31, 2018 , we had outstanding forward contracts to buy foreign currency with a notional value of $123.7 million and to sell foreign currency with a notional value of $82.6 million . All of the currency derivatives expire within one year and are for USD equivalents. The counterparties to the forward contracts are large financial institutions; however, the risk of loss to us in the event of nonperformance by a counterparty could be significant to our financial position or results of operations. At December 31, 2017 , we had outstanding forward contracts to buy foreign currency with a notional value of $135.5 million and to sell foreign currency with a notional value of $97.7 million . Cash Flow Hedges For derivative instruments that are designated and qualify as a cash flow hedge, the change in fair value of the derivative is recognized as a component of other comprehensive income (loss) until the hedged item is recognized into earnings. Gains and losses on the derivatives representing hedge ineffectiveness are recognized currently in earnings. We had the following notional amounts of outstanding commodity contracts that were entered into to hedge forecasted purchases: December 31, 2018 2017 ($ in millions) Natural gas $ 58.4 $ 39.2 Other commodities 58.1 53.6 Total notional $ 116.5 $ 92.8 As of December 31, 2018 , the counterparties to these commodity contracts were Wells Fargo, Citibank and JPMorgan Chase Bank, National Association, all of which are major financial institutions. We use cash flow hedges for certain raw material and energy costs such as copper, zinc, lead, ethane, electricity and natural gas to provide a measure of stability in managing our exposure to price fluctuations associated with forecasted purchases of raw materials and energy used in our manufacturing process. At December 31, 2018 , we had open derivative contract positions through 2022 . If all open futures contracts had been settled on December 31, 2018 , we would have recognized a pretax loss of $2.6 million . If commodity prices were to remain at December 31, 2018 levels, approximately $2.3 million of deferred losses, net of tax, would be reclassified into earnings during the next twelve months. The actual effect on earnings will be dependent on actual commodity prices when the forecasted transactions occur. We use interest rate swaps as a means of minimizing cash flow fluctuations that may arise from volatility in interest rates of our variable-rate borrowings. In April 2016, we entered into three tranches of forward starting interest rate swaps whereby we agreed to pay fixed rates to the counterparties who, in turn, pay us floating rates on $1,100.0 million , $900.0 million and $400.0 million of our underlying floating-rate debt obligations. Each tranche’s term length is for twelve months beginning on December 31, 2016, December 31, 2017 and December 31, 2018, respectively. The counterparties to the agreements are SMBC Capital Markets, Inc., Wells Fargo, PNC Bank, National Association, and Toronto-Dominion Bank. These counterparties are large financial institutions; however, the risk of loss to us in the event of nonperformance by a counterparty could be significant to our financial position or results of operations. We have designated the swaps as cash flow hedges of the risk of changes in interest payments associated with our variable-rate borrowings. Accordingly, the remaining swap agreement has been recorded at its fair market value of $5.3 million and is included in other current assets on the accompanying consolidated balance sheet, with the corresponding gain deferred as a component of other comprehensive loss. For the years ended December 31, 2018 and 2017 , $8.9 million and $3.1 million , respectively, of income was recorded to interest expense on the accompanying consolidated statements of operations related to these swap agreements. At December 31, 2018 , we had open interest rate swaps designated as cash flow hedges with maximum terms through 2019. If all open interest rate swap contracts had been settled on December 31, 2018 , we would have recognized a pretax gain of $5.3 million . If interest rates were to remain at December 31, 2018 levels, $5.3 million of deferred gains would be reclassified into earnings during the next twelve months. The actual effect on earnings will be dependent on actual interest rates when the forecasted transactions occur. Fair Value Hedges We use interest rate swaps as a means of managing interest expense and floating interest rate exposure to optimal levels. For derivative instruments that are designated and qualify as a fair value hedge, the gain or loss on the derivative as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in current earnings. We include the gain or loss on the hedged items (fixed-rate borrowings) in the same line item, interest expense, as the offsetting loss or gain on the related interest rate swaps. As of both December 31, 2018 and 2017 , the total notional amounts of our interest rate swaps designated as fair value hedges were $500.0 million . In April 2016, we entered into interest rate swaps on $250.0 million of our underlying fixed-rate debt obligations, whereby we agreed to pay variable rates to the counterparties who, in turn, pay us fixed rates. The counterparties to these agreements are Toronto-Dominion Bank and SMBC Capital Markets, Inc., both of which are major financial institutions. In October 2016, we entered into interest rate swaps on an additional $250.0 million of our underlying fixed-rate debt obligations, whereby we agreed to pay variable rates to the counterparties who, in turn, pay us fixed rates. The counterparties to these agreements are PNC Bank, National Association and Wells Fargo, both of which are major financial institutions. We have designated the April 2016 and October 2016 interest rate swap agreements as fair value hedges of the risk of changes in the value of fixed-rate debt due to changes in interest rates for a portion of our fixed-rate borrowings. Accordingly, the swap agreements have been recorded at their fair market value of $33.7 million and are included in other long-term liabilities on the accompanying consolidated balance sheet, with a corresponding decrease in the carrying amount of the related debt. For the year ended December 31, 2018 , $2.1 million of expense has been recorded to interest expense on the accompanying consolidated statements of operations related to these swap agreements. For the years ended December 31, 2017 and 2016, $2.9 million and $2.6 million , respectively, of income has been recorded to interest expense on the accompanying consolidated statements of operations related to these swap agreements. Financial Statement Impacts We present our derivative assets and liabilities in our consolidated balance sheets on a net basis whenever we have a legally enforceable master netting agreement with the counterparty to our derivative contracts. We use these agreements to manage and substantially reduce our potential counterparty credit risk. The following table summarizes the location and fair value of the derivative instruments on our consolidated balance sheets. The table disaggregates our net derivative assets and liabilities into gross components on a contract-by-contract basis before giving effect to master netting arrangements: December 31, 2018 2017 Asset Derivatives: ($ in millions) Other current assets Derivatives designated as hedging instruments: Interest rate contracts - gains $ 5.3 $ 6.9 Commodity contracts - gains — 11.4 Commodity contracts - losses — (0.1 ) Derivatives not designated as hedging instruments: Foreign exchange contracts - gains 0.9 2.0 Foreign exchange contracts - losses (0.5 ) (1.0 ) Total other current assets 5.7 19.2 Other assets Derivatives designated as hedging instruments: Interest rate contracts - gains — 3.6 Commodity contracts - gains 0.9 — Commodity contracts - losses (0.2 ) — Total other assets 0.7 3.6 Total Asset Derivatives (1) $ 6.4 $ 22.8 Liability Derivatives: Accrued liabilities Derivatives designated as hedging instruments: Commodity contracts - losses $ 4.9 $ 3.8 Commodity contracts - gains (1.9 ) — Derivatives not designated as hedging instruments: Foreign exchange contracts - losses 0.6 — Foreign exchange contracts - gains (0.1 ) — Total accrued liabilities 3.5 3.8 Other liabilities Derivatives designated as hedging instruments: Interest rate contracts - losses 33.7 28.1 Commodity contract - losses 0.5 — Commodity contract - gains (0.1 ) — Total other liabilities 34.1 28.1 Total Liability Derivatives (1) $ 37.6 $ 31.9 (1) Does not include the impact of cash collateral received from or provided to counterparties. The following table summarizes the effects of derivative instruments on our consolidated statements of operations: Amount of (Loss) Gain Years Ended December 31, Location of (Loss) Gain 2018 2017 2016 Derivatives – Cash Flow Hedges ($ in millions) Recognized in other comprehensive loss: Commodity contracts ——— $ (4.8 ) $ (2.1 ) $ 16.7 Interest rate contracts ——— 3.7 4.0 9.6 $ (1.1 ) $ 1.9 $ 26.3 Reclassified from accumulated other comprehensive loss into income: Interest rate contracts Interest expense $ 8.9 $ 3.1 $ — Commodity contracts Cost of goods sold 5.4 1.5 (5.8 ) $ 14.3 $ 4.6 $ (5.8 ) Derivatives – Fair Value Hedges Interest rate contracts Interest expense $ (2.1 ) $ 3.0 $ 3.7 Derivatives Not Designated as Hedging Instruments Commodity contracts Cost of goods sold $ — $ — $ (0.4 ) Foreign exchange contracts Selling and administration (5.4 ) 1.8 (11.1 ) $ (5.4 ) $ 1.8 $ (11.5 ) Credit Risk and Collateral By using derivative instruments, we are exposed to credit and market risk. If a counterparty fails to fulfill its performance obligations under a derivative contract, our credit risk will equal the fair-value gain in a derivative. Generally, when the fair value of a derivative contract is positive, this indicates that the counterparty owes us, thus creating a repayment risk for us. When the fair value of a derivative contract is negative, we owe the counterparty and, therefore, assume no repayment risk. We minimize the credit (or repayment) risk in derivative instruments by entering into transactions with high-quality counterparties. We monitor our positions and the credit ratings of our counterparties, and we do not anticipate non-performance by the counterparties. Based on the agreements with our various counterparties, cash collateral is required to be provided when the net fair value of the derivatives, with the counterparty, exceeds a specific threshold. If the threshold is exceeded, cash is either provided by the counterparty to us if the value of the derivatives is our asset, or cash is provided by us to the counterparty if the value of the derivatives is our liability. As of December 31, 2018 and 2017 , this threshold was not exceeded. In all instances where we are party to a master netting agreement, we offset the receivable or payable recognized upon payment of cash collateral against the fair value amounts recognized for derivative instruments that have also been offset under such master netting agreements.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	NOTE 25 . FAIR VALUE MEASUREMENTS Assets and liabilities recorded at fair value in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels are directly related to the amount of subjectivity associated with the inputs to fair valuation of these assets and liabilities. We are required to separately disclose assets and liabilities measured at fair value on a recurring basis, from those measured at fair value on a nonrecurring basis. Nonfinancial assets measured at fair value on a nonrecurring basis are intangible assets and goodwill, which are reviewed for impairment annually in the fourth quarter and/or when circumstances or other events indicate that impairment may have occurred. Determining which hierarchical level an asset or liability falls within requires significant judgment. The following table summarizes the assets and liabilities measured at fair value in the consolidated balance sheets: Balance at December 31, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets ($ in millions) Interest rate swaps $ — $ 5.3 $ — $ 5.3 Commodity contracts — 0.7 — 0.7 Foreign exchange contracts — 0.4 — 0.4 Total Assets $ — $ 6.4 $ — $ 6.4 Liabilities Interest rate swaps $ — $ 33.7 $ — $ 33.7 Commodity contracts — 3.4 — 3.4 Foreign exchange contracts — 0.5 — 0.5 Total Liabilities $ — $ 37.6 $ — $ 37.6 Balance at December 31, 2017 Assets Interest rate swaps $ — $ 10.5 $ — $ 10.5 Commodity contracts — 11.3 — 11.3 Foreign exchange contracts — 1.0 — 1.0 Total Assets $ — $ 22.8 $ — $ 22.8 Liabilities Interest rate swaps $ — $ 28.1 $ — $ 28.1 Commodity contracts — 3.8 — 3.8 Total Liabilities $ — $ 31.9 $ — $ 31.9 Interest Rate Swaps Interest rate swap financial instruments were valued using the “income approach” valuation technique. This method used valuation techniques to convert future amounts to a single present amount. The measurement was based on the value indicated by current market expectations about those future amounts. We use interest rate swaps as a means of managing interest expense and floating interest rate exposure to optimal levels. Commodity Contracts Commodity contract financial instruments were valued primarily based on prices and other relevant information observable in market transactions involving identical or comparable assets or liabilities including both forward and spot prices for commodities. We use commodity derivative contracts for certain raw materials and energy costs such as copper, zinc, lead, ethane, electricity and natural gas to provide a measure of stability in managing our exposure to price fluctuations. Foreign Currency Contracts Foreign currency contract financial instruments were valued primarily based on relevant information observable in market transactions involving identical or comparable assets or liabilities including both forward and spot prices for currencies. We enter into forward sales and purchase contracts to manage currency risk resulting from purchase and sale commitments denominated in foreign currencies. Financial Instruments The carrying values of cash and cash equivalents, accounts receivable and accounts payable approximated fair values due to the short-term maturities of these instruments. The fair value of our long-term debt was determined based on current market rates for debt of similar risk and maturities. The following table summarizes the fair value measurements of debt and the actual debt recorded on our balance sheets: Fair Value Measurements Level 1 Level 2 Level 3 Total Amount recorded on balance sheets ($ in millions) Balance at December 31, 2018 $ — $ 3,137.2 $ 153.0 $ 3,290.2 $ 3,230.3 Balance at December 31, 2017 — 3,758.0 153.0 3,911.0 3,612.0 Nonrecurring Fair Value Measurements In addition to assets and liabilities that are recorded at fair value on a recurring basis, we record assets and liabilities at fair value on a nonrecurring basis as required by ASC 820. There were no assets measured at fair value on a nonrecurring basis as of December 31, 2018 and 2017 .

SUPPLEMENTAL GUARANTOR FINANCIA

SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2018
Supplemental Guarantor Financial Information [Abstract]
SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION	NOTE 26 . SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION In October 2015, Blue Cube Spinco LLC (the Issuer) issued $720.0 million aggregate principal amount of 9.75% senior notes due October 15, 2023 and $500.0 million aggregate principal amount 10.00% senior notes due October 15, 2025 (collectively, the Notes). During 2016, the Notes were registered under the Securities Act of 1933, as amended. The Issuer was formed on March 13, 2015 as a wholly owned subsidiary of DowDuPont and upon closing of the Acquisition became a 100% owned subsidiary of Olin (the Parent Guarantor). The Notes are fully and unconditionally guaranteed by the Parent Guarantor. The following condensed consolidating financial information presents the condensed consolidating balance sheets as of December 31, 2018 and 2017 , and the related condensed consolidating statements of operations, comprehensive income (loss) and cash flows for each of the years in the three-year period ended December 31, 2018 of (a) the Parent Guarantor, (b) the Issuer, (c) the non-guarantor subsidiaries, (d) elimination entries necessary to consolidate the Parent Guarantor with the Issuer and the non-guarantor subsidiaries and (e) Olin on a consolidated basis. Investments in consolidated subsidiaries are presented under the equity method of accounting. CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Assets Current assets: Cash and cash equivalents $ 92.0 $ — $ 86.8 $ — $ 178.8 Receivables, net 99.7 — 676.6 — 776.3 Intercompany receivables — — 2,558.2 (2,558.2 ) — Income taxes receivable 2.6 — 3.3 — 5.9 Inventories, net 161.4 — 550.0 — 711.4 Other current assets 220.2 — 1.8 (187.0 ) 35.0 Total current assets 575.9 — 3,876.7 (2,745.2 ) 1,707.4 Property, plant and equipment, net 651.4 — 2,830.7 — 3,482.1 Investment in subsidiaries 6,943.3 4,286.9 — (11,230.2 ) — Deferred income taxes 7.3 — 27.4 (8.4 ) 26.3 Other assets 24.3 — 1,126.1 — 1,150.4 Long-term receivables—affiliates — 1,247.2 — (1,247.2 ) — Intangible assets, net 0.3 — 511.3 — 511.6 Goodwill — 966.3 1,153.3 — 2,119.6 Total assets $ 8,202.5 $ 6,500.4 $ 9,525.5 $ (15,231.0 ) $ 8,997.4 Liabilities and Shareholders’ Equity Current liabilities: Current installments of long-term debt $ 0.9 $ — $ 125.0 $ — $ 125.9 Accounts payable 90.1 — 549.4 (3.0 ) 636.5 Intercompany payables 2,558.2 — — (2,558.2 ) — Income taxes payable 3.9 — 18.7 — 22.6 Accrued liabilities 150.3 — 367.5 (184.5 ) 333.3 Total current liabilities 2,803.4 — 1,060.6 (2,745.7 ) 1,118.3 Long-term debt 1,357.5 1,746.9 — — 3,104.4 Accrued pension liability 439.1 — 235.2 — 674.3 Deferred income taxes — 6.0 521.3 (8.4 ) 518.9 Long-term payables—affiliates 469.6 — 777.6 (1,247.2 ) — Other liabilities 300.7 5.5 443.1 — 749.3 Total liabilities 5,370.3 1,758.4 3,037.8 (4,001.3 ) 6,165.2 Commitments and contingencies Shareholders’ equity: Common stock 165.3 — 14.6 (14.6 ) 165.3 Additional paid-in capital 2,247.4 4,125.7 4,808.2 (8,933.9 ) 2,247.4 Accumulated other comprehensive loss (651.0 ) — (6.9 ) 6.9 (651.0 ) Retained earnings 1,070.5 616.3 1,671.8 (2,288.1 ) 1,070.5 Total shareholders’ equity 2,832.2 4,742.0 6,487.7 (11,229.7 ) 2,832.2 Total liabilities and shareholders’ equity $ 8,202.5 $ 6,500.4 $ 9,525.5 $ (15,231.0 ) $ 8,997.4 CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2017 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Assets Current assets: Cash and cash equivalents $ 57.1 $ — $ 161.3 $ — $ 218.4 Receivables, net 95.6 — 637.6 — 733.2 Intercompany receivables — — 2,093.2 (2,093.2 ) — Income taxes receivable 11.7 — 6.3 (1.1 ) 16.9 Inventories, net 155.4 — 527.2 — 682.6 Other current assets 206.2 — 5.3 (163.4 ) 48.1 Total current assets 526.0 — 3,430.9 (2,257.7 ) 1,699.2 Property, plant and equipment, net 544.4 — 3,031.4 — 3,575.8 Investment in subsidiaries 6,680.4 4,092.3 — (10,772.7 ) — Deferred income taxes 38.1 — 34.5 (36.2 ) 36.4 Other assets 45.9 — 1,162.5 — 1,208.4 Long-term receivables—affiliates — 2,137.8 — (2,137.8 ) — Intangible assets, net 0.3 — 578.2 — 578.5 Goodwill — 966.3 1,153.7 — 2,120.0 Total assets $ 7,835.1 $ 7,196.4 $ 9,391.2 $ (15,204.4 ) $ 9,218.3 Liabilities and Shareholders’ Equity Current liabilities: Current installments of long-term debt $ 0.7 $ — $ — $ — $ 0.7 Accounts payable 83.2 — 590.0 (3.4 ) 669.8 Intercompany payables 2,093.2 — — (2,093.2 ) — Income taxes payable — — 10.5 (1.1 ) 9.4 Accrued liabilities 117.7 — 318.1 (161.4 ) 274.4 Total current liabilities 2,294.8 — 918.6 (2,259.1 ) 954.3 Long-term debt 839.4 2,522.2 249.7 — 3,611.3 Accrued pension liability 406.7 — 229.2 — 635.9 Deferred income taxes — 3.0 544.4 (36.2 ) 511.2 Long-term payables—affiliates 1,250.0 — 887.8 (2,137.8 ) — Other liabilities 290.5 5.6 455.8 — 751.9 Total liabilities 5,081.4 2,530.8 3,285.5 (4,433.1 ) 6,464.6 Commitments and contingencies Shareholders’ equity: Common stock 167.1 — 14.6 (14.6 ) 167.1 Additional paid-in capital 2,280.9 4,125.7 4,808.2 (8,933.9 ) 2,280.9 Accumulated other comprehensive loss (484.6 ) — (4.6 ) 4.6 (484.6 ) Retained earnings 790.3 539.9 1,287.5 (1,827.4 ) 790.3 Total shareholders’ equity 2,753.7 4,665.6 6,105.7 (10,771.3 ) 2,753.7 Total liabilities and shareholders’ equity $ 7,835.1 $ 7,196.4 $ 9,391.2 $ (15,204.4 ) $ 9,218.3 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2018 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Sales $ 1,423.8 $ — $ 5,937.0 $ (414.7 ) $ 6,946.1 Operating expenses: Cost of goods sold 1,153.1 — 5,083.7 (414.7 ) 5,822.1 Selling and administration 206.0 — 224.6 — 430.6 Restructuring charges — — 21.9 — 21.9 Acquisition-related costs 1.0 — — — 1.0 Other operating (loss) income (3.0 ) — 9.4 — 6.4 Operating income 60.7 — 616.2 — 676.9 Losses of non-consolidated affiliates (19.7 ) — — — (19.7 ) Equity income in subsidiaries 310.7 289.6 — (600.3 ) — Interest expense 68.6 153.3 26.9 (5.6 ) 243.2 Interest income 5.8 — 1.4 (5.6 ) 1.6 Non-operating pension income (expense) 26.6 — (4.9 ) — 21.7 Income before taxes 315.5 136.3 585.8 (600.3 ) 437.3 Income tax (benefit) provision (12.4 ) (35.1 ) 156.9 — 109.4 Net income $ 327.9 $ 171.4 $ 428.9 $ (600.3 ) $ 327.9 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2017 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Sales $ 1,330.3 $ — $ 5,344.9 $ (406.8 ) $ 6,268.4 Operating expenses: Cost of goods sold 1,195.5 — 4,766.2 (406.8 ) 5,554.9 Selling and administration 157.0 — 212.8 — 369.8 Restructuring charges 1.7 — 35.9 — 37.6 Acquisition-related costs 12.8 — — — 12.8 Other operating (loss) income (11.1 ) — 14.4 — 3.3 Operating (loss) income (47.8 ) — 344.4 — 296.6 Earnings of non-consolidated affiliates 1.8 — — — 1.8 Equity income in subsidiaries 638.4 357.6 — (996.0 ) — Interest expense 44.5 165.8 13.0 (5.9 ) 217.4 Interest income 6.3 — 1.4 (5.9 ) 1.8 Non-operating pension income (expense) 38.5 — (4.1 ) — 34.4 Income before taxes 592.7 191.8 328.7 (996.0 ) 117.2 Income tax provision (benefit) 43.2 (310.0 ) (165.5 ) — (432.3 ) Net income $ 549.5 $ 501.8 $ 494.2 $ (996.0 ) $ 549.5 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2016 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Sales $ 1,321.3 $ — $ 4,720.2 $ (490.9 ) $ 5,550.6 Operating expenses: Cost of goods sold 1,153.0 — 4,282.4 (490.9 ) 4,944.5 Selling and administration 162.1 — 185.1 — 347.2 Restructuring charges 0.8 — 112.1 — 112.9 Acquisition-related costs 47.4 — 1.4 — 48.8 Other operating (loss) income (2.2 ) — 12.8 — 10.6 Operating (loss) income (44.2 ) — 152.0 — 107.8 Earnings of non-consolidated affiliates 1.7 — — — 1.7 Equity income in subsidiaries 16.2 139.0 — (155.2 ) — Interest expense 38.8 153.9 4.7 (5.5 ) 191.9 Interest income 4.7 — 4.2 (5.5 ) 3.4 Non-operating pension income (expense) 48.3 — (3.5 ) — 44.8 Income (loss) before taxes (12.1 ) (14.9 ) 148.0 (155.2 ) (34.2 ) Income tax (benefit) provision (8.2 ) (57.6 ) 35.5 — (30.3 ) Net (loss) income $ (3.9 ) $ 42.7 $ 112.5 $ (155.2 ) $ (3.9 ) CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) Year Ended December 31, 2018 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net income $ 327.9 $ 171.4 $ 428.9 $ (600.3 ) $ 327.9 Other comprehensive loss, net of tax: Foreign currency translation adjustments, net — — (22.2 ) — (22.2 ) Unrealized losses on derivative contracts, net (11.7 ) — — — (11.7 ) Pension and postretirement liability adjustments, net (69.6 ) — (5.3 ) — (74.9 ) Amortization of prior service costs and actuarial losses, net 26.3 — 2.0 — 28.3 Total other comprehensive loss, net of tax (55.0 ) — (25.5 ) — (80.5 ) Comprehensive income $ 272.9 $ 171.4 $ 403.4 $ (600.3 ) $ 247.4 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) Year Ended December 31, 2017 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net income $ 549.5 $ 501.8 $ 494.2 $ (996.0 ) $ 549.5 Other comprehensive income, net of tax: Foreign currency translation adjustments, net — — 31.7 — 31.7 Unrealized losses on derivative contracts, net (1.7 ) — — — (1.7 ) Pension and postretirement liability adjustments, net (12.3 ) — (9.3 ) — (21.6 ) Amortization of prior service costs and actuarial losses, net 15.3 — 1.7 — 17.0 Total other comprehensive income, net of tax 1.3 — 24.1 — 25.4 Comprehensive income $ 550.8 $ 501.8 $ 518.3 $ (996.0 ) $ 574.9 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) Year Ended December 31, 2016 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net (loss) income $ (3.9 ) $ 42.7 $ 112.5 $ (155.2 ) $ (3.9 ) Other comprehensive income (loss), net of tax: Foreign currency translation adjustments, net — — (12.0 ) — (12.0 ) Unrealized gains on derivative contracts, net 19.7 — — — 19.7 Pension and postretirement liability adjustments, net (25.3 ) — (12.2 ) — (37.5 ) Amortization of prior service costs and actuarial losses, net 10.9 — 1.4 — 12.3 Total other comprehensive income (loss), net of tax 5.3 — (22.8 ) — (17.5 ) Comprehensive income (loss) $ 1.4 $ 42.7 $ 89.7 $ (155.2 ) $ (21.4 ) CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2018 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net operating activities $ 529.8 $ — $ 378.0 $ — $ 907.8 Investing Activities Capital expenditures (149.8 ) — (235.4 ) — (385.2 ) Proceeds from disposition of property, plant and equipment — — 2.9 — 2.9 Distributions from consolidated subsidiaries, net 95.0 95.0 — (190.0 ) — Net investing activities (54.8 ) 95.0 (232.5 ) (190.0 ) (382.3 ) Financing Activities Long-term debt: Borrowings 550.0 — 20.0 — 570.0 Repayments (21.0 ) (780.4 ) (144.7 ) — (946.1 ) Common stock repurchased and retired (50.0 ) — — — (50.0 ) Stock options exercised 3.4 — — — 3.4 Dividends paid (133.6 ) (95.0 ) (95.0 ) 190.0 (133.6 ) Debt issuance costs (8.5 ) — — — (8.5 ) Intercompany financing activities (780.4 ) 780.4 — — — Net financing activities (440.1 ) (95.0 ) (219.7 ) 190.0 (564.8 ) Effect of exchange rate changes on cash and cash equivalents — — (0.3 ) — (0.3 ) Net increase (decrease) in cash and cash equivalents 34.9 — (74.5 ) — (39.6 ) Cash and cash equivalents, beginning of year 57.1 — 161.3 — 218.4 Cash and cash equivalents, end of year $ 92.0 $ — $ 86.8 $ — $ 178.8 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2017 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net operating activities $ 472.0 $ — $ 176.8 $ — $ 648.8 Investing Activities Capital expenditures (89.1 ) — (205.2 ) — (294.3 ) Payments under long-term supply contracts — — (209.4 ) — (209.4 ) Proceeds from disposition of property, plant and equipment — — 5.2 — 5.2 Distribution from consolidated subsidiaries, net 2.7 — — (2.7 ) — Net investing activities (86.4 ) — (409.4 ) (2.7 ) (498.5 ) Financing Activities Long-term debt: Borrowings 620.0 1,375.0 40.5 — 2,035.5 Repayments (690.8 ) (1,334.1 ) (13.0 ) — (2,037.9 ) Stock options exercised 29.8 — — — 29.8 Dividends paid (133.0 ) — (2.7 ) 2.7 (133.0 ) Debt issuance costs (8.3 ) (2.9 ) — — (11.2 ) Intercompany financing activities (171.4 ) (38.0 ) 209.4 — — Net financing activities (353.7 ) — 234.2 2.7 (116.8 ) Effect of exchange rate changes on cash and cash equivalents — — 0.4 — 0.4 Net increase in cash and cash equivalents 31.9 — 2.0 — 33.9 Cash and cash equivalents, beginning of year 25.2 — 159.3 — 184.5 Cash and cash equivalents, end of year $ 57.1 $ — $ 161.3 $ — $ 218.4 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2016 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net operating activities $ 702.6 $ — $ (99.4 ) $ — $ 603.2 Investing Activities Capital expenditures (65.7 ) — (212.3 ) — (278.0 ) Business acquired and related transactions, net of cash acquired (69.5 ) — — — (69.5 ) Payments under long-term supply contracts — — (175.7 ) — (175.7 ) Proceeds from sale/leaseback of equipment — — 40.4 — 40.4 Proceeds from disposition of property, plant and equipment 0.2 — 0.3 — 0.5 Proceeds from disposition of affiliated companies 8.8 — — — 8.8 Net investing activities (126.2 ) — (347.3 ) — (473.5 ) Financing Activities Long-term debt: Borrowings — — 230.0 — 230.0 Repayments (335.6 ) (67.5 ) (32.2 ) — (435.3 ) Stock options exercised 0.5 — — — 0.5 Excess tax benefits from stock-based compensation 0.4 — — — 0.4 Dividends paid (132.1 ) — — — (132.1 ) Debt issuance costs — (1.0 ) — — (1.0 ) Intercompany financing activities (203.8 ) 68.5 135.3 — — Net financing activities (670.6 ) — 333.1 — (337.5 ) Effect of exchange rate changes on cash and cash equivalents — — 0.3 — 0.3 Net decrease in cash and cash equivalents (94.2 ) — (113.3 ) — (207.5 ) Cash and cash equivalents, beginning of year 119.4 — 272.6 — 392.0 Cash and cash equivalents, end of year $ 25.2 $ — $ 159.3 $ — $ 184.5

OTHER FINANCIAL DATA

OTHER FINANCIAL DATA	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Data [Abstract]
OTHER FINANCIAL DATA	NOTE 27 . OTHER FINANCIAL DATA Quarterly Data (Unaudited) ($ in millions, except per share data) 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Year Sales $ 1,710.3 $ 1,728.4 $ 1,872.4 $ 1,635.0 $ 6,946.1 Cost of goods sold 1,528.7 1,460.7 1,441.7 1,391.0 5,822.1 Net income 20.9 58.6 195.1 53.3 327.9 Net income per common share: Basic 0.13 0.35 1.17 0.32 1.97 Diluted 0.12 0.35 1.16 0.32 1.95 Common dividends per share 0.20 0.20 0.20 0.20 0.80 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Year Sales $ 1,567.1 $ 1,526.5 $ 1,554.9 $ 1,619.9 $ 6,268.4 Cost of goods sold 1,397.5 1,407.9 1,349.3 1,400.2 5,554.9 Net income (loss) 13.4 (5.9 ) 52.7 489.3 549.5 Net income (loss) per common share: Basic 0.08 (0.04 ) 0.32 2.93 3.31 Diluted 0.08 (0.04 ) 0.31 2.89 3.26 Common dividends per share 0.20 0.20 0.20 0.20 0.80

ACCOUNTING POLICIES (Policies)

ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of Olin and all majority-owned subsidiaries. Investment in our affiliates are accounted for on the equity method. Accordingly, we include only our share of earnings or losses of these affiliates in consolidated net income (loss). Certain reclassifications were made to prior year amounts to conform to the 2018 presentation.
Revenue Recognition	Revenue Recognition In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, “Revenue from Contracts with Customers” (ASU 2014-09), which amends Accounting Standards Codification (ASC) 605 “Revenue Recognition” and creates a new topic, ASC 606 “Revenue from Contracts with Customers” (ASC 606). Subsequent to the issuance of ASU 2014-09, ASC 606 was amended by various updates that amend and clarify the impact and implementation of the aforementioned update. We adopted these updates on January 1, 2018 using the modified retrospective transition method. The cumulative effect of applying the updates did not have a material impact on our consolidated financial statements. The most significant impact the updates had was on our accounting policies and disclosures on revenue recognition. We derive our revenues primarily from the manufacturing and delivery of goods to customers. Revenues are recognized on sales of goods at the time when control of those goods is transferred to our customers at an amount that reflects the consideration to which we expect to be entitled in exchange for those goods. We primarily sell our goods directly to customers, and to a lesser extent, through distributors. Payment terms are typically 30 to 90 days from date of invoice. Our contracts do not typically have a significant financing component. Right to payment is determined at the point in time in which control has transferred to the customer. A performance obligation is a promise in a contract to transfer a distinct good to the customer. At contract inception, we assess the goods promised in our contracts with customers and identify a performance obligation for each promise to transfer to the customer a good (or bundle of goods) that is distinct. A contract’s transaction price is based on the price stated in the contract and allocated to each distinct performance obligation and revenue is recognized when the performance obligation is satisfied. Substantially all of our contracts have a single distinct performance obligation or multiple performance obligations which are distinct and represent individual promises within the contract. Substantially all of our performance obligations are satisfied at a single point in time, when control is transferred, which is generally upon shipment or delivery as stated in the contract terms. All taxes assessed by governmental authorities that are both imposed on and concurrent with our revenue-producing transactions and collected from our customers are excluded from the measurement of the transaction price. Shipping and handling fees billed to customers are included in revenue and are considered activities to fulfill the promise to transfer the good. Allowances for estimated returns, discounts and rebates are considered variable consideration, which may be constrained, and are estimated and recognized when sales are recorded. The estimates are based on various market data, historical trends and information from customers. Actual returns, discounts and rebates have not been materially different from estimates. For all contracts that have a duration of one year or less at contract inception, we do not adjust the promised amount of consideration for the effects of a significant financing component. Substantially all of our revenue is derived from contracts with an original expected length of time of one year or less and for which we recognize revenue for the amount in which we have the right to invoice at the point in time in which control has transferred to the customer. However, a portion of our revenue is derived from long-term contracts which have contract periods that vary between one to multi-year. Certain of these contracts represent contracts with minimum purchase obligations, which can be substantially different than the actual revenue recognized. Such contracts consist of varying types of products across our chemical businesses. Certain contracts include variable volumes and/or variable pricing with pricing provisions tied to commodity, consumer price or other indices. The transaction price allocated to the remaining performance obligations related to our contracts was excluded from the disclosure of our remaining performance obligations based on the following practical expedients that we elected to apply: (i) contracts with index-based pricing or variable volume attributes in which such variable consideration is allocated entirely to a wholly unsatisfied performance obligation; and (ii) contracts with an original expected duration of one year or less. Refer to Note 21 “Segment Information” for information regarding the disaggregation of revenue by primary geographical markets and major product lines.
Cost of Goods Sold and Selling and Administration Expenses	Cost of Goods Sold and Selling and Administration Expenses Cost of goods sold includes the costs of inventory sold, related purchasing, distribution and warehousing costs, costs incurred for shipping and handling, depreciation and amortization expense related to these activities and environmental remediation costs and recoveries. Selling and administration expenses include personnel costs associated with sales, marketing and administration, research and development, legal and legal-related costs, consulting and professional services fees, advertising expenses, depreciation expense related to these activities, foreign currency translation and other similar costs.
Acquisition-related Costs	Acquisition-related Costs Acquisition-related costs include advisory, legal, accounting and other professional fees incurred in connection with the purchase and integration of our acquisitions. Acquisition-related costs also may include costs which arise as a result of acquisitions, including contractual change in control provisions, contract termination costs, compensation payments related to the acquisition or pension and other postretirement benefit plan settlements.
Other Operating Income	Other Operating Income Other operating income consists of miscellaneous operating income items, which are related to our business activities, and gains (losses) on disposition of property, plant and equipment. Included in other operating income were the following: Years Ended December 31, 2018 2017 2016 ($ in millions) Gains (losses) on disposition of property, plant and equipment, net $ (2.0 ) $ 3.1 $ (0.7 ) Gains on insurance recoveries 8.0 — 11.0 Other 0.4 0.2 0.3 Other operating income $ 6.4 $ 3.3 $ 10.6 Other operating income for 2018 included an $8.0 million insurance recovery for a second quarter 2017 business interruption at our Freeport, TX vinyl chloride monomer facility partially offset by a $1.7 million loss on the sale of land. The gains on disposition of property, plant and equipment in 2017 included a gain of $3.3 million from the sale of a former manufacturing facility. The gains on insurance recoveries in 2016 included insurance recoveries for property damage and business interruption related to a 2008 Henderson, NV chlor alkali facility incident.
Other Income (Expense)	Other Income (Expense) Other income (expense) consists of non-operating income and expense items which are not related to our primary business activities.
Foreign Currency Translation	Foreign Currency Translation Our worldwide operations utilize the U.S. dollar (USD) or local currency as the functional currency, where applicable. For foreign entities where the USD is the functional currency, gains and losses resulting from balance sheet translations are included in selling and administration. For foreign entities where the local currency is the functional currency, assets and liabilities denominated in local currencies are translated into USD at end-of-period exchange rates and the resultant translation adjustments are included in accumulated other comprehensive loss. Assets and liabilities denominated in other than the local currency are remeasured into the local currency prior to translation into USD and the resultant exchange gains or losses are included in income in the period in which they occur. Income and expenses are translated into USD using an approximation of the average rate prevailing during the period. We change the functional currency of our separate and distinct foreign entities only when significant changes in economic facts and circumstances indicate clearly that the functional currency has changed.
Cash and Cash Equivalents	Cash and Cash Equivalents All highly liquid investments, with a maturity of three months or less at the date of purchase, are considered to be cash equivalents.
Short-Term Investments	Short-Term Investments We classify our marketable securities as available-for-sale, which are reported at fair market value with unrealized gains and losses included in accumulated other comprehensive loss, net of applicable taxes. The fair value of marketable securities is determined by quoted market prices. Realized gains and losses on sales of investments, as determined on the specific identification method, and declines in value of securities judged to be other-than-temporary are included in other income (expense) in the consolidated statements of operations. Interest and dividends on all securities are included in interest income and other income (expense), respectively. As of December 31, 2018 and 2017 , we had no short-term investments recorded on our consolidated balance sheets.
Allowance for Doubtful Accounts Receivable	Allowance for Doubtful Accounts Receivable We evaluate the collectibility of accounts receivable based on a combination of factors. We estimate an allowance for doubtful accounts as a percentage of net sales based on historical bad debt experience. This estimate is periodically adjusted when we become aware of a specific customer’s inability to meet its financial obligations (e.g., bankruptcy filing) or as a result of changes in the overall aging of accounts receivable. While we have a large number of customers that operate in diverse businesses and are geographically dispersed, a general economic downturn in any of the industry segments in which we operate could result in higher than expected defaults, and, therefore, the need to revise estimates for the provision for doubtful accounts could occur.
Inventories	Inventories Inventories are valued at the lower of cost and net realizable value. For U.S. inventories, inventory costs are determined principally by the last-in, first-out (LIFO) method of inventory accounting while for international inventories, inventory costs are determined principally by the first-in, first-out (FIFO) method of inventory accounting. Costs for other inventories have been determined principally by the average-cost method (primarily operating supplies, spare parts and maintenance parts). Elements of costs in inventories include raw materials, direct labor and manufacturing overhead.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are recorded at cost. Depreciation is computed on a straight-line basis over the estimated useful lives of the related assets. Interest costs incurred to finance expenditures for major long-term construction projects are capitalized as part of the historical cost and included in property, plant and equipment and are depreciated over the useful lives of the related assets. Leasehold improvements are amortized over the term of the lease or the estimated useful life of the improvement, whichever is shorter. Start-up costs are expensed as incurred. Expenditures for maintenance and repairs are charged to expense when incurred while the costs of significant improvements, which extend the useful life of the underlying asset, are capitalized. Property, plant and equipment are reviewed for impairment when conditions indicate that the carrying values of the assets may not be recoverable. Such impairment conditions include an extended period of idleness or a plan of disposal. If such impairment indicators are present or other factors exist that indicate that the carrying amount of an asset may not be recoverable, we determine whether impairment has occurred through the use of an undiscounted cash flow analysis at the lowest level for which identifiable cash flows exist. For our Chlor Alkali Products and Vinyls, Epoxy and Winchester segments, the lowest level for which identifiable cash flows exist is the operating facility level or an appropriate grouping of operating facilities level. The amount of impairment loss, if any, is measured by the difference between the net book value of the assets and the estimated fair value of the related assets.
Asset Retirement Obligations	Asset Retirement Obligations We record the fair value of an asset retirement obligation associated with the retirement of a tangible long-lived asset as a liability in the period incurred. The liability is measured at discounted fair value and is adjusted to its present value in subsequent periods as accretion expense is recorded. The corresponding asset retirement costs are capitalized as part of the carrying amount of the related long-lived asset and depreciated over the asset’s useful life. Asset retirement obligations are reviewed annually in the fourth quarter and/or when circumstances or other events indicate that changes underlying retirement assumptions may have occurred. The activities of our asset retirement obligations were as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 54.3 $ 55.4 Accretion 3.2 3.0 Spending (8.0 ) (8.8 ) Foreign currency translation adjustments (0.2 ) 0.2 Adjustments 10.9 4.5 Ending balance $ 60.2 $ 54.3 At December 31, 2018 and 2017 , our consolidated balance sheets included an asset retirement obligation of $49.6 million and $43.8 million , respectively, which were classified as other noncurrent liabilities. In 2018, we had net adjustments that increased the asset retirement obligation by $10.9 million which was primarily related to additional asset retirement obligations for leased assets. In 2017 , we had net adjustments that increased the asset retirement obligation by $4.5 million which was primarily comprised of increases in estimated costs for certain assets.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Accumulated other comprehensive loss consists of foreign currency translation adjustments, pension and postretirement liability adjustments, pension and postretirement amortization of prior service costs and actuarial losses and net unrealized (losses) gains on derivative contracts.
Goodwill	Goodwill Goodwill is not amortized, but is reviewed for impairment annually in the fourth quarter and/or when circumstances or other events indicate that impairment may have occurred. Accounting Standards Codification (ASC) 350 “Intangibles—Goodwill and Other” (ASC 350) permits entities to make a qualitative assessment of whether it is more likely than not that a reporting unit’s fair value is less than its carrying amount before applying the two-step goodwill impairment test. Circumstances that are considered as part of the qualitative assessment and could trigger the two-step impairment test include, but are not limited to: a significant adverse change in the business climate; a significant adverse legal judgment; adverse cash flow trends; an adverse action or assessment by a government agency; unanticipated competition; decline in our stock price; and a significant restructuring charge within a reporting unit. We define reporting units at the business segment level or one level below the business segment level. For purposes of testing goodwill for impairment, goodwill has been allocated to our reporting units to the extent it relates to each reporting unit. Based upon our qualitative assessment, it is more likely than not that the fair value of our reporting units are greater than their carrying amounts as of December 31, 2018 . No impairment charges were recorded for 2018 , 2017 or 2016 . It is our practice, at a minimum, to perform a quantitative goodwill impairment test in the fourth quarter every three years. In the fourth quarter of 2016, we performed our triennial quantitative goodwill impairment test for our reporting units. We use a discounted cash flow approach to develop the estimated fair value of a reporting unit when a quantitative test is performed. Management judgment is required in developing the assumptions for the discounted cash flow model. We also corroborate our discounted cash flow analysis by evaluating a market-based approach that considers earnings before interest, taxes, depreciation and amortization (EBITDA) multiples from a representative sample of comparable public companies. As a further indicator that each reporting unit has been valued appropriately using a discounted cash flow model, the aggregate fair value of all reporting units is reconciled to the total market value of Olin. An impairment would be recorded if the carrying amount of a reporting unit exceeded the estimated fair value. Based on the aforementioned analysis, the estimated fair value of our reporting units substantially exceeded the carrying value of the reporting units. The discount rate, profitability assumptions and terminal growth rate of our reporting units and the cyclical nature of the chlor alkali industry were the material assumptions utilized in the discounted cash flow model used to estimate the fair value of each reporting unit. The discount rate reflects a weighted-average cost of capital, which is calculated based on observable market data. Some of this data (such as the risk free or treasury rate and the pretax cost of debt) are based on the market data at a point in time. Other data (such as the equity risk premium) are based upon market data over time for a peer group of companies in the chemical manufacturing or distribution industries with a market capitalization premium added, as applicable. The discounted cash flow analysis requires estimates, assumptions and judgments about future events. Our analysis uses our internally generated long-range plan. Our discounted cash flow analysis uses the assumptions in our long-range plan about terminal growth rates, forecasted capital expenditures and changes in future working capital requirements to determine the implied fair value of each reporting unit. The long-range plan reflects management judgment, supplemented by independent chemical industry analyses which provide multi-year industry operating and pricing forecasts. We believe the assumptions used in our goodwill impairment analysis are appropriate and result in reasonable estimates of the implied fair value of each reporting unit. However, given the economic environment and the uncertainties regarding the impact on our business, there can be no assurance that our estimates and assumptions, made for purposes of our goodwill impairment testing, will prove to be an accurate prediction of the future. If our assumptions regarding future performance are not achieved, we may be required to record goodwill impairment charges in future periods. It is not possible at this time to determine if any such future impairment charge would result or, if it does, whether such charge would be material.
Intangible Assets	Intangible Assets In conjunction with our acquisitions, we have obtained access to the customer contracts and relationships, trade names, acquired technology and other intellectual property of the acquired companies. These relationships are expected to provide economic benefit for future periods. Amortization expense is recognized on a straight-line basis over the estimated lives of the related assets. The amortization period of customer contracts and relationships, trade names, acquired technology and other intellectual property represents our best estimate of the expected usage or consumption of the economic benefits of the acquired assets, which is based on the company’s historical experience. Intangible assets with finite lives are reviewed for impairment when conditions indicate that the carrying values of the assets may not be recoverable. Circumstances that are considered as part of the qualitative assessment and could trigger a quantitative impairment test include, but are not limited to: a significant adverse change in the business climate; a significant adverse legal judgment including asset specific factors; adverse cash flow trends; an adverse action or assessment by a government agency; unanticipated competition; decline in our stock price; and a significant restructuring charge within a reporting unit. Based upon our qualitative assessment, it is more likely than not that the fair value of our intangible assets are greater than the carrying amount as of December 31, 2018 . No impairment of our intangible assets were recorded in 2018 , 2017 or 2016 .
Environmental Liabilities and Expenditures	Environmental Liabilities and Expenditures Accruals (charges to income) for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated, based upon current law and existing technologies. These amounts, which are not discounted and are exclusive of claims against third parties, are adjusted periodically as assessment and remediation efforts progress or additional technical or legal information becomes available. Environmental costs are capitalized if the costs increase the value of the property and/or mitigate or prevent contamination from future operations.
Income Taxes	Income Taxes Deferred taxes are provided for differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided to offset deferred tax assets if, based on the available evidence, it is more likely than not that some or all of the value of the deferred tax assets will not be realized.
Derivative Financial Instruments	Derivative Financial Instruments We are exposed to market risk in the normal course of our business operations due to our purchases of certain commodities, our ongoing investing and financing activities and our operations that use foreign currencies. The risk of loss can be assessed from the perspective of adverse changes in fair values, cash flows and future earnings. We have established policies and procedures governing our management of market risks and the use of financial instruments to manage exposure to such risks. We use hedge accounting treatment for a significant amount of our business transactions whose risks are covered using derivative instruments. The hedge accounting treatment provides for the deferral of gains or losses on derivative instruments until such time as the related transactions occur.
Concentration of Credit Risk	Concentration of Credit Risk Accounts receivable is the principal financial instrument which subjects us to a concentration of credit risk. Credit is extended based upon the evaluation of a customer’s financial condition and, generally, collateral is not required. Concentrations of credit risk with respect to receivables are somewhat limited due to our large number of customers, the diversity of these customers’ businesses and the geographic dispersion of such customers. Our accounts receivable are predominantly derived from sales denominated in USD or the Euro. We maintain an allowance for doubtful accounts based upon the expected collectibility of all trade receivables.
Fair Value	Fair Value Fair value is defined as the price at which an asset could be exchanged in a current transaction between knowledgeable, willing parties or the amount that would be paid to transfer a liability to a new obligor, not the amount that would be paid to settle the liability with the creditor. Where available, fair value is based on observable market prices or parameters or derived from such prices or parameters. Where observable prices or inputs are not available, valuation models are applied. These valuation techniques involve some level of management estimation and judgment, the degree of which is dependent on the price transparency for the instruments or market and the instruments’ complexity. Assets and liabilities recorded at fair value in the consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels, defined by ASC 820 “Fair Value Measurement” (ASC 820), and directly related to the amount of subjectivity associated with the inputs to fair valuation of these assets and liabilities, are as follows: Level 1 — Inputs were unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 — Inputs (other than quoted prices included in Level 1) were either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. Level 3 — Inputs reflected management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration was given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.
Retirement-Related Benefits	Retirement-Related Benefits We account for our defined benefit pension plans and non-pension postretirement benefit plans using actuarial models required by ASC 715 “Compensation—Retirement Benefits” (ASC 715). These models use an attribution approach that generally spreads the financial impact of changes to the plan and actuarial assumptions over the average remaining service lives of the employees in the plan. Changes in liability due to changes in actuarial assumptions such as discount rate, rate of compensation increases and mortality, as well as annual deviations between what was assumed and what was experienced by the plan are treated as actuarial gains or losses. The principle underlying the required attribution approach is that employees render service over their average remaining service lives on a relatively smooth basis and, therefore, the accounting for benefits earned under the pension or non-pension postretirement benefits plans should follow the same relatively smooth pattern. Substantially all domestic defined benefit pension plan participants are no longer accruing benefits; therefore, actuarial gains and losses are amortized based upon the remaining life expectancy of the inactive plan participants. For the years ended December 31, 2018 and 2017 , the average remaining life expectancy of the inactive participants in the domestic defined benefit pension plan were 18 and 19 years, respectively. One of the key assumptions for the net periodic pension calculation is the expected long-term rate of return on plan assets, used to determine the “market-related value of assets.” The “market-related value of assets” recognizes differences between the plan’s actual return and expected return over a five year period. The required use of an expected long-term rate of return on the market-related value of plan assets may result in recognized pension income that is greater or less than the actual returns of those plan assets in any given year. Over time, however, the expected long-term returns are designed to approximate the actual long-term returns and, therefore, result in a pattern of income and expense recognition that more closely matches the pattern of the services provided by the employees. As differences between actual and expected returns are recognized over five years, they subsequently generate gains and losses that are subject to amortization over the average remaining life expectancy of the inactive plan participants, as described in the preceding paragraph. We use long-term historical actual return information, the mix of investments that comprise plan assets, and future estimates of long-term investment returns and inflation by reference to external sources to develop the expected long-term rate of return on plan assets as of December 31. The discount rate assumptions used for pension and non-pension postretirement benefit plan accounting reflect the rates available on high-quality fixed-income debt instruments on December 31 of each year. The rate of compensation increase is based upon our long-term plans for such increases. For retiree medical plan accounting, we review external data and our own historical trends for healthcare costs to determine the healthcare cost trend rates. For our defined benefit pension and other postretirement benefit plans, we measure service and interest costs by applying the specific spot rates along the yield curve to the plans’ estimated cash flows. We believe this approach provides a more precise measurement of service and interest costs by aligning the timing of the plans’ liability cash flows to the corresponding spot rates on the yield curve.
Stock-Based Compensation	Stock-Based Compensation We measure the cost of employee services received in exchange for an award of equity instruments, such as stock options, performance shares and restricted stock, based on the grant-date fair value of the award. This cost is recognized over the period during which an employee is required to provide service in exchange for the award, the requisite service period (usually the vesting period). An initial measurement is made of the cost of employee services received in exchange for an award of liability instruments based on its current fair value and the value of that award is subsequently remeasured at each reporting date through the settlement date. Changes in fair value of liability awards during the requisite service period are recognized as compensation cost over that period. The fair value of each option granted, which typically vests ratably over three years, but not less than one year, was estimated on the date of grant, using the Black-Scholes option-pricing model with the following assumptions: 2018 2017 2016 Dividend yield 2.43 % 2.69 % 6.09 % Risk-free interest rate 2.72 % 2.06 % 1.35 % Expected volatility 32 % 34 % 32 % Expected life (years) 6.0 6.0 6.0 Weighted-average grant fair value (per option) $ 8.89 $ 7.78 $ 1.90 Weighted-average exercise price $ 32.94 $ 29.82 $ 13.14 Shares granted 927,000 1,621,000 1,670,400 Dividend yield was based on our current dividend yield as of the option grant date. Risk-free interest rate was based on zero coupon U.S. Treasury securities rates for the expected life of the options. Expected volatility was based on our historical stock price movements, as we believe that historical experience is the best available indicator of the expected volatility. Expected life of the option grant was based on historical exercise and cancellation patterns, as we believe that historical experience is the best estimate for future exercise patterns.

ACCOUNTING POLICIES (Tables)

ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Other operating income	Included in other operating income were the following: Years Ended December 31, 2018 2017 2016 ($ in millions) Gains (losses) on disposition of property, plant and equipment, net $ (2.0 ) $ 3.1 $ (0.7 ) Gains on insurance recoveries 8.0 — 11.0 Other 0.4 0.2 0.3 Other operating income $ 6.4 $ 3.3 $ 10.6
Asset retirement obligation activity	The activities of our asset retirement obligations were as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 54.3 $ 55.4 Accretion 3.2 3.0 Spending (8.0 ) (8.8 ) Foreign currency translation adjustments (0.2 ) 0.2 Adjustments 10.9 4.5 Ending balance $ 60.2 $ 54.3
Schedule of assumptions for the Black-Scholes option pricing model	The fair value of each option granted, which typically vests ratably over three years, but not less than one year, was estimated on the date of grant, using the Black-Scholes option-pricing model with the following assumptions: 2018 2017 2016 Dividend yield 2.43 % 2.69 % 6.09 % Risk-free interest rate 2.72 % 2.06 % 1.35 % Expected volatility 32 % 34 % 32 % Expected life (years) 6.0 6.0 6.0 Weighted-average grant fair value (per option) $ 8.89 $ 7.78 $ 1.90 Weighted-average exercise price $ 32.94 $ 29.82 $ 13.14 Shares granted 927,000 1,621,000 1,670,400

RESTRUCTURING CHARGES (Tables)

RESTRUCTURING CHARGES (Tables)	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost [Table Text Block]	The following table summarizes the 2018 , 2017 and 2016 activities by major component of these restructuring actions and the remaining balances of accrued restructuring costs as of December 31, 2018 : Employee severance and related benefit costs Lease and other contract termination costs Employee relocation costs Facility exit costs Write-off of equipment and facility Total ($ in millions) Balance at January 1, 2016 $ 4.6 $ 2.1 $ — $ — $ — $ 6.7 2016 restructuring charges 5.1 13.6 2.1 15.5 76.6 112.9 Amounts utilized (6.3 ) (8.2 ) (2.1 ) (13.7 ) (76.6 ) (106.9 ) Balance at December 31, 2016 3.4 7.5 — 1.8 — 12.7 2017 restructuring charges 2.0 22.1 0.3 11.7 1.5 37.6 Amounts utilized (3.6 ) (26.3 ) (0.3 ) (13.5 ) (1.5 ) (45.2 ) Balance at December 31, 2017 1.8 3.3 — — — 5.1 2018 restructuring charges 1.7 5.6 — 12.0 2.6 21.9 Amounts utilized (2.0 ) (2.9 ) — (11.3 ) (2.6 ) (18.8 ) Balance at December 31, 2018 $ 1.5 $ 6.0 $ — $ 0.7 $ — $ 8.2
Restructuring and Related Costs [Table Text Block]	The following table summarizes the cumulative restructuring charges of these 2018, 2016, 2014 and 2010 restructuring actions by major component through December 31, 2018 : Chlor Alkali Products and Vinyls Winchester Total Becancour Capacity Reductions Oxford Geelong ($ in millions) Write-off of equipment and facility $ 3.5 $ 78.1 $ — $ 2.6 $ 84.2 Employee severance and related benefit costs 2.7 5.9 14.7 1.3 24.6 Facility exit costs 5.9 33.8 2.3 — 42.0 Pension and other postretirement benefits curtailment — — 4.1 — 4.1 Employee relocation costs — 1.7 6.0 — 7.7 Lease and other contract termination costs 6.1 40.2 — 0.2 46.5 Total cumulative restructuring charges $ 18.2 $ 159.7 $ 27.1 $ 4.1 $ 209.1

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Share Table	Years ended December 31, 2018 2017 2016 Computation of Income (Loss) per Share (In millions, except per share data) Net income (loss) $ 327.9 $ 549.5 $ (3.9 ) Basic shares 166.8 166.2 165.2 Basic net income (loss) per share $ 1.97 $ 3.31 $ (0.02 ) Diluted shares: Basic shares 166.8 166.2 165.2 Stock-based compensation 1.6 2.3 — Diluted shares 168.4 168.5 165.2 Diluted net income (loss) per share $ 1.95 $ 3.26 $ (0.02 )

ACCOUNTS RECEIVABLES (Tables)

ACCOUNTS RECEIVABLES (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
AR Facilities [Table Text Block]	The following table summarizes the AR Facilities activity: December 31, 2018 2017 ($ in millions) Beginning Balance $ 182.3 $ 126.1 Gross receivables sold 1,372.3 1,655.2 Payments received from customers on sold accounts (1,422.2 ) (1,599.0 ) Ending Balance $ 132.4 $ 182.3

ALLOWANCE FOR DOUBTFUL ACCOUN_2

ALLOWANCE FOR DOUBTFUL ACCOUNTS RECEIVABLES (Tables)	12 Months Ended
	Dec. 31, 2018
Accounts Receivable, Net [Abstract]
Allowance for Doubtful Accounts Receivable	Allowance for doubtful accounts receivable consisted of the following: December 31, 2018 2017 ($ in millions) Beginning balance $ 12.3 $ 10.1 Provisions charged 1.7 1.8 Write-offs, net of recoveries (0.7 ) (0.1 ) Foreign currency translation adjustments (0.4 ) 0.5 Ending balance $ 12.9 $ 12.3

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventories	December 31, 2018 2017 ($ in millions) Supplies $ 66.4 $ 66.1 Raw materials 66.7 75.3 Work in process 139.6 127.8 Finished goods 488.5 462.6 761.2 731.8 LIFO reserve (49.8 ) (49.2 ) Inventories, net $ 711.4 $ 682.6

OTHER ASSETS (Tables)

OTHER ASSETS (Tables)	12 Months Ended
	Dec. 31, 2018
Other Assets [Abstract]
Schedule of Other Assets	Included in other assets were the following: December 31, 2018 2017 ($ in millions) Supply contracts $ 1,099.5 $ 1,137.1 Investments in non-consolidated affiliates 8.8 28.5 Other 42.1 42.8 Other assets $ 1,150.4 $ 1,208.4

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of property, plant and equipment along with respective useful lives	December 31, Useful Lives 2018 2017 ($ in millions) Land and improvements to land 10-20 Years $ 276.9 $ 281.7 Buildings and building equipment 10-30 Years 387.6 382.4 Machinery and equipment 3-20 Years 5,252.0 5,028.4 Leasehold improvements 5.2 3.9 Construction in progress 341.4 212.5 Property, plant and equipment 6,263.1 5,908.9 Accumulated depreciation (2,781.0 ) (2,333.1 ) Property, plant and equipment, net $ 3,482.1 $ 3,575.8

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	Changes in the carrying value of goodwill were as follows: Chlor Alkali Products and Vinyls Epoxy Total ($ in millions) Balance at January 1, 2017 $ 1,831.3 $ 286.7 $ 2,118.0 Foreign currency translation adjustment 1.6 0.4 2.0 Balance at December 31, 2017 1,832.9 287.1 2,120.0 Foreign currency translation adjustment (0.3 ) (0.1 ) (0.4 ) Balance at December 31, 2018 $ 1,832.6 $ 287.0 $ 2,119.6
Schedule of Finite-Lived Intangible Assets [Table Text Block]	Intangible assets consisted of the following: December 31, 2018 2017 Useful Lives Gross Amount Accumulated Amortization Net Gross Amount Accumulated Amortization Net ($ in millions) Customers, customer contracts and relationships 10-15 Years $ 675.2 $ (211.9 ) $ 463.3 $ 679.5 $ (163.6 ) $ 515.9 Trade name 5 Years 7.0 (4.6 ) 2.4 7.1 (3.2 ) 3.9 Acquired technology 7 Years 85.4 (39.6 ) 45.8 86.1 (27.7 ) 58.4 Other 10 Years 0.7 (0.6 ) 0.1 2.3 (2.0 ) 0.3 Total intangible assets $ 768.3 $ (256.7 ) $ 511.6 $ 775.0 $ (196.5 ) $ 578.5

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Instruments [Abstract]
Schedule of long-term debt	December 31, 2018 2017 Notes payable: ($ in millions) Variable-rate Senior Term Loan Facility, due 2022 (4.02% and 3.57% at December 31, 2018 and 2017, respectively) $ 543.0 $ 1,323.4 Variable-rate Recovery Zone bonds, due 2024-2035 (3.67% and 3.27% at December 31, 2018 and 2017, respectively) 103.0 103.0 Variable-rate Go Zone bonds, due 2024 (3.67% and 3.27% at December 31, 2018 and 2017, respectively) 50.0 50.0 Variable-rate Industrial development and environmental improvement obligations, due 2025 (2.52% and 1.27% at December 31, 2018 and 2017, respectively) 2.9 2.9 9.75%, due 2023 720.0 720.0 10.00%, due 2025 500.0 500.0 5.50%, due 2022 200.0 200.0 5.125%, due 2027 500.0 500.0 5.00%, due 2030 550.0 — Senior Revolving Credit Facility — 20.0 Receivables Financing Agreement 125.0 249.7 Capital lease obligations 4.2 3.7 Total notes payable 3,298.1 3,672.7 Deferred debt issuance costs (34.1 ) (32.6 ) Interest rate swaps (33.7 ) (28.1 ) Total debt 3,230.3 3,612.0 Amounts due within one year 125.9 0.7 Total long-term debt $ 3,104.4 $ 3,611.3

PENSION PLANS (Tables)

PENSION PLANS (Tables)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Changes in benefit obligation and plan assets	Changes in the benefit obligation and plan assets were as follows: December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total Change in Benefit Obligation ($ in millions) Benefit obligation at beginning of year $ 2,579.9 $ 303.4 $ 2,883.3 $ 2,466.2 $ 251.0 $ 2,717.2 Service cost 1.4 9.7 11.1 1.2 8.2 9.4 Interest cost 80.6 5.7 86.3 81.3 5.3 86.6 Actuarial (gain) loss (163.2 ) 1.5 (161.7 ) 161.7 9.6 171.3 Benefits paid (133.2 ) (3.7 ) (136.9 ) (130.5 ) (4.2 ) (134.7 ) Plan participant’s contributions — 1.2 1.2 — 1.0 1.0 Plan amendments — (0.4 ) (0.4 ) — 1.7 1.7 Foreign currency translation adjustments — (15.1 ) (15.1 ) — 30.8 30.8 Benefit obligation at end of year $ 2,365.5 $ 302.3 $ 2,667.8 $ 2,579.9 $ 303.4 $ 2,883.3 December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total Change in Plan Assets ($ in millions) Fair value of plans’ assets at beginning of year $ 2,172.5 $ 74.4 $ 2,246.9 $ 2,012.0 $ 66.5 $ 2,078.5 Actual return on plans’ assets (113.9 ) (2.1 ) (116.0 ) 290.6 5.0 295.6 Employer contributions 0.4 1.8 2.2 0.4 2.2 2.6 Benefits paid (133.2 ) (2.2 ) (135.4 ) (130.5 ) (3.0 ) (133.5 ) Foreign currency translation adjustments — (4.7 ) (4.7 ) — 3.7 3.7 Fair value of plans’ assets at end of year $ 1,925.8 $ 67.2 $ 1,993.0 $ 2,172.5 $ 74.4 $ 2,246.9 December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total Funded Status ($ in millions) Qualified plans $ (436.1 ) $ (232.8 ) $ (668.9 ) $ (403.7 ) $ (226.9 ) $ (630.6 ) Non-qualified plans (3.6 ) (2.3 ) (5.9 ) (3.7 ) (2.1 ) (5.8 ) Total funded status $ (439.7 ) $ (235.1 ) $ (674.8 ) $ (407.4 ) $ (229.0 ) $ (636.4 )
Amounts recognized in consolidated balance sheets	Amounts recognized in the consolidated balance sheets consisted of: December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total ($ in millions) Accrued benefit in current liabilities $ (0.4 ) $ (0.1 ) $ (0.5 ) $ (0.4 ) $ (0.1 ) $ (0.5 ) Accrued benefit in noncurrent liabilities (439.3 ) (235.0 ) (674.3 ) (407.0 ) (228.9 ) (635.9 ) Accumulated other comprehensive loss 796.5 56.0 852.5 735.1 51.4 786.5 Net balance sheet impact $ 356.8 $ (179.1 ) $ 177.7 $ 327.7 $ (177.6 ) $ 150.1
Schedule of projected and accumulated benefit obligation, and fair value of plan assets	December 31, 2018 2017 ($ in millions) Projected benefit obligation $ 2,667.8 $ 2,883.3 Accumulated benefit obligation 2,641.3 2,851.0 Fair value of plan assets 1,993.0 2,246.9
Components of net periodic benefit income (loss)	Years Ended December 31, 2018 2017 2016 Components of Net Periodic Benefit (Income) Costs ($ in millions) Service cost $ 11.1 $ 9.4 $ 9.0 Interest cost 86.3 86.6 87.7 Expected return on plans’ assets (146.5 ) (149.4 ) (154.5 ) Amortization of prior service cost 0.1 2.2 — Recognized actuarial loss 34.5 24.8 20.7 Net periodic benefit (income) costs $ (14.5 ) $ (26.4 ) $ (37.1 ) Included in Other Comprehensive Loss (Pretax) Liability adjustment $ 100.6 $ 26.9 $ 66.1 Amortization of prior service costs and actuarial losses (34.6 ) (27.0 ) (20.7 )
Assumptions used in calculations	U.S. Pension Benefits Foreign Pension Benefits Weighted-Average Assumptions 2018 2017 2016 2018 2017 2016 Discount rate—periodic benefit cost 3.6 % (1) 4.1 % 4.4 % 2.2 % 2.3 % 2.7 % Expected return on assets 7.75 % 7.75 % 7.75 % 5.2 % 5.6 % 6.0 % Rate of compensation increase 3.0 % 3.0 % 3.0 % 2.9 % 3.0 % 3.0 % Discount rate—benefit obligation 4.2 % 3.6 % 4.1 % 2.2 % 2.2 % 2.3 % (1) The discount rate—periodic benefit cost for our domestic qualified pension plan is comprised of the discount rate used to determine interest costs of 3.2% and the discount rate used to determine service costs of 3.7% .
Schedule of Rate of Returns by Asset Class Considered in Setting Long-Term Rate of Return Assumption	The following rates of return by asset class were considered in setting the long-term rate of return assumption: U.S. equities 9% to 13% Non-U.S. equities 6% to 11% Fixed income/cash 5% to 9% Alternative investments 5% to 15% Absolute return strategies 8% to 12%
Pension plan asset allocation by asset class	Our pension plan asset allocations at December 31, 2018 and 2017 by asset class were as follows: Percentage of Plan Assets Asset Class 2018 2017 U.S. equities 12 % 19 % Non-U.S. equities 15 % 17 % Fixed income/cash 32 % 24 % Alternative investments 24 % 21 % Absolute return strategies 17 % 19 % Total 100 % 100 %
Target allocation and ranges	As of December 31, 2018 , the following target allocation and ranges have been set for each asset class: Asset Class Target Allocation Target Range U.S. equities (1) 20 % 15-31 Non-U.S. equities (1) 16 % 2-32 Fixed income/cash (1) 43 % 21-75 Alternative investments 4 % 0-29 Absolute return strategies 17 % 10-30 (1) The target allocation for these asset classes include alternative investments, primarily hedge funds, based on the underlying investments in each hedge fund.
Pension Plan Investments Measured At Fair Value [Text Block]	The following table summarizes our domestic and foreign defined benefit pension plan assets measured at fair value as of December 31, 2018 : Asset Class Investments Measured at Net Asset Value Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Equity securities ($ in millions) U.S. equities $ 111.5 $ 136.6 $ — $ — $ 248.1 Non-U.S. equities 255.8 44.5 0.9 — 301.2 Fixed income/cash Cash — 55.7 — — 55.7 Government treasuries 0.7 — 175.0 — 175.7 Corporate debt instruments 83.7 — 139.2 — 222.9 Asset-backed securities 153.6 — 17.6 — 171.2 Alternative investments Hedge fund of funds 440.8 — — — 440.8 Real estate funds 22.3 — — — 22.3 Private equity funds 7.6 — — — 7.6 Absolute return strategies 347.5 — — — 347.5 Total assets $ 1,423.5 $ 236.8 $ 332.7 $ — $ 1,993.0 The following table summarizes our domestic and foreign defined benefit pension plan assets measured at fair value as of December 31, 2017 : Asset Class Investments Measured at Net Asset Value Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Equity securities ($ in millions) U.S. equities $ 230.7 $ 203.7 $ — $ — $ 434.4 Non-U.S. equities 321.9 55.6 14.6 — 392.1 Fixed income/cash Cash — 41.9 — — 41.9 Government treasuries 0.7 — 151.2 — 151.9 Corporate debt instruments 80.9 — 115.1 — 196.0 Asset-backed securities 104.3 — 44.0 — 148.3 Alternative investments Hedge fund of funds 430.7 — — — 430.7 Real estate funds 21.8 — — — 21.8 Private equity funds 11.5 — — — 11.5 Absolute return strategies 418.3 — — — 418.3 Total assets $ 1,620.8 $ 301.2 $ 324.9 $ — $ 2,246.9

POSTRETIREMENT BENEFITS (Tables

POSTRETIREMENT BENEFITS (Tables)	12 Months Ended
	Dec. 31, 2018
POSTRETIREMENT BENEFITS Disclosure [Abstract]
Postretirement plan change in benefit obligation	Changes in the benefit obligation were as follows: December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total Change in Benefit Obligation ($ in millions) Benefit obligation at beginning of year $ 40.6 $ 10.2 $ 50.8 $ 43.6 $ 8.6 $ 52.2 Service cost 0.9 0.4 1.3 0.8 0.3 1.1 Interest cost 1.2 0.3 1.5 1.2 0.3 1.5 Actuarial (gain) loss (2.0 ) (0.1 ) (2.1 ) (0.6 ) 1.0 0.4 Benefits paid (3.2 ) (0.4 ) (3.6 ) (4.4 ) (0.3 ) (4.7 ) Foreign currency translation adjustments — (0.9 ) (0.9 ) — 0.3 0.3 Benefit obligation at end of year $ 37.5 $ 9.5 $ 47.0 $ 40.6 $ 10.2 $ 50.8 December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total ($ in millions) Funded status $ (37.5 ) $ (9.5 ) $ (47.0 ) $ (40.6 ) $ (10.2 ) $ (50.8 )
Amounts recognized in consolidated balance sheet	Amounts recognized in the consolidated balance sheets consisted of: December 31, 2018 December 31, 2017 U.S. Foreign Total U.S. Foreign Total ($ in millions) Accrued benefit in current liabilities $ (3.6 ) $ (0.3 ) $ (3.9 ) $ (4.0 ) $ (0.3 ) $ (4.3 ) Accrued benefit in noncurrent liabilities (33.9 ) (9.2 ) (43.1 ) (36.6 ) (9.9 ) (46.5 ) Accumulated other comprehensive loss 20.1 1.0 21.1 24.7 0.9 25.6 Net balance sheet impact $ (17.4 ) $ (8.5 ) $ (25.9 ) $ (15.9 ) $ (9.3 ) $ (25.2 )
Components of net periodic benefit cost	Years Ended December 31, 2018 2017 2016 Components of Net Periodic Benefit Cost ($ in millions) Service cost $ 1.3 $ 1.1 $ 1.2 Interest cost 1.5 1.5 1.6 Amortization of prior service cost — (2.2 ) (2.6 ) Recognized actuarial loss 2.4 2.1 2.3 Net periodic benefit cost $ 5.2 $ 2.5 $ 2.5 Included in Other Comprehensive Loss (Pretax) Liability adjustment $ (2.1 ) $ 0.4 $ (5.1 ) Amortization of prior service costs and actuarial losses (2.4 ) 0.1 0.3
Schedule of actuarial assumption	December 31, Weighted-Average Assumptions 2018 2017 2016 Discount rate—periodic benefit cost 3.5 % 3.8 % 4.1 % Discount rate—benefit obligation 4.1 % 3.5 % 3.8 %
Assumed healthcare cost trend rates	The assumed healthcare cost trend rates for pre-65 retirees were as follows: December 31, 2018 2017 Healthcare cost trend rate assumed for next year 7.5 % 8.0 % Rate that the cost trend rate gradually declines to 4.5 % 4.5 % Year that the rate reaches the ultimate rate 2024 2024

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Components of income tax provision	Years ended December 31, 2018 2017 2016 Components of Income (Loss) Before Taxes ($ in millions) Domestic $ 288.0 $ 53.3 $ (23.3 ) Foreign 149.3 63.9 (10.9 ) Income (loss) before taxes $ 437.3 $ 117.2 $ (34.2 ) Components of Income Tax Provision (Benefit) Current expense (benefit): Federal $ 21.7 $ (4.0 ) $ (11.6 ) State 5.1 3.0 0.9 Foreign 48.0 24.1 15.7 74.8 23.1 5.0 Deferred expense (benefit): Federal 27.0 (549.6 ) (10.1 ) State (0.8 ) 14.6 (5.1 ) Foreign 8.4 79.6 (20.1 ) 34.6 (455.4 ) (35.3 ) Income tax provision (benefit) $ 109.4 $ (432.3 ) $ (30.3 )
Effective tax rate reconciliation	The following table accounts for the difference between the actual tax provision and the amounts obtained by applying the statutory U.S. federal income tax rate to the income (loss) before taxes. Years ended December 31, Effective Tax Rate Reconciliation (Percent) 2018 2017 2016 Statutory federal tax rate 21.0 % 35.0 % 35.0 % State income taxes, net 2.0 (1.2 ) 8.0 Foreign rate differential 1.8 (7.7 ) (25.1 ) U.S. tax on foreign earnings 1.1 (70.8 ) 24.4 Salt depletion (2.4 ) (16.1 ) 45.4 Change in valuation allowance 3.8 76.0 (0.7 ) Remeasurement of U.S. state deferred taxes (0.6 ) 10.2 9.4 Change in tax contingencies (0.7 ) (7.7 ) (9.7 ) U.S. Tax Cuts and Jobs Act (0.8 ) (373.5 ) — Share-based payments — (5.7 ) — Dividends paid to Contributing Employee Ownership Plan (0.1 ) (0.6 ) 2.8 Return to provision (0.1 ) (0.6 ) 5.3 U.S. Federal tax credits (0.4 ) (4.2 ) 0.6 Other, net 0.4 (2.0 ) (6.8 ) Effective tax rate 25.0 % (368.9 )% 88.6 %
Components of deferred tax assets and liabilities	December 31, Components of Deferred Tax Assets and Liabilities 2018 2017 Deferred tax assets: ($ in millions) Pension and postretirement benefits $ 156.8 $ 147.3 Environmental reserves 31.9 33.2 Asset retirement obligations 15.5 14.0 Accrued liabilities 37.0 37.6 Tax credits 19.5 37.1 Net operating losses 50.2 53.3 Capital loss carryforward 2.0 2.1 Other miscellaneous items 23.9 11.2 Total deferred tax assets 336.8 335.8 Valuation allowance (147.4 ) (121.4 ) Net deferred tax assets 189.4 214.4 Deferred tax liabilities: Property, plant and equipment 541.8 550.3 Intangible amortization 61.6 67.3 Inventory and prepaids 8.3 1.0 Partnerships 65.2 67.5 Taxes on unremitted earnings 5.1 3.1 Total deferred tax liabilities 682.0 689.2 Net deferred tax liability $ (492.6 ) $ (474.8 )
Summary of Valuation Allowance	The activity of our deferred income tax valuation allowance was as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 121.4 $ 29.0 Increases to valuation allowances 31.9 94.5 U.S. Tax Cuts and Jobs Act — 2.2 Decreases to valuation allowances (0.9 ) (5.0 ) Currency translation adjustment (5.0 ) 0.7 Ending balance $ 147.4 $ 121.4
Unrecognized tax benefits	The amounts of unrecognized tax benefits were as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 36.3 $ 38.4 Increase for current year tax positions 2.1 2.9 Increase for prior year tax positions 0.3 5.4 Reductions due to statute of limitations — (0.1 ) Decrease for prior year tax positions (4.9 ) (9.2 ) Decrease due to tax settlements — (1.1 ) Ending balance $ 33.8 $ 36.3
Tax years subject to examination	For our primary tax jurisdictions, the tax years that remain subject to examination are as follows: Tax Years U.S. federal income tax 2013 - 2017 U.S. state income tax 2006 - 2017 Canadian federal income tax 2012 - 2017 Brazil 2014 - 2017 Germany 2015 - 2017 China 2014 - 2017 The Netherlands 2014 - 2017

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2018
Accrued Liabilities, Current [Abstract]
Accrued Liabilities	Included in accrued liabilities were the following: December 31, 2018 2017 ($ in millions) Accrued compensation and payroll taxes $ 100.0 $ 80.6 Tax-related accruals 23.1 21.7 Accrued interest 48.9 37.4 Legal and professional costs 54.4 34.8 Accrued employee benefits 25.3 21.7 Environmental (current portion only) 17.0 20.0 Asset retirement obligation (current portion only) 10.6 10.5 Restructuring reserves (current portion only) 7.3 3.3 Other 46.7 44.4 Accrued liabilities $ 333.3 $ 274.4

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation expense	Stock-based compensation expense was as follows: Years ended December 31, 2018 2017 2016 ($ in millions) Stock-based compensation $ 19.3 $ 18.7 $ 11.2 Mark-to-market adjustments (10.1 ) 4.5 3.0 Total expense $ 9.2 $ 23.2 $ 14.2
Stock Options Activity	Stock option transactions were as follows: Exercisable Shares Option Price Weighted-Average Option Price Options Weighted-Average Exercise Price Outstanding at January 1, 2018 5,342,526 $13.14-31.90 $ 22.72 2,603,962 $ 21.78 Granted 927,000 32.94-32.94 32.94 Exercised (204,064 ) 13.14-29.75 17.68 Canceled (201,246 ) 13.14-32.94 25.92 Outstanding at December 31, 2018 5,864,216 $13.14-32.94 $ 24.40 3,571,732 $ 22.27
Stock Options Exercisable, Exercise Price Range	The following table provides certain information with respect to stock options exercisable at December 31, 2018 : Range of Options Exercisable Weighted-Average Exercise Price Options Outstanding Weighted-Average Exercise Price Under $20.00 1,129,630 $ 14.19 1,579,848 $ 13.89 $20.00 - $26.00 1,290,236 23.77 1,290,236 23.77 Over $26.00 1,151,866 28.49 2,994,132 30.22 3,571,732 5,864,216
Common shares reserved and available for grant or purchase	At December 31, 2018 , common shares reserved for issuance and available for grant or purchase under the following plans consisted of: Number of Shares Stock Option Plans Reserved for Issuance Available for Grant or Purchase (1) 2000 long term incentive plan 44,130 — 2003 long term incentive plan 215,584 — 2006 long term incentive plan 278,270 — 2009 long term incentive plan 1,873,421 — 2014 long term incentive plan 2,098,802 — 2016 long term incentive plan 2,326,334 — 2018 long term incentive plan 9,263,665 9,252,665 Total under stock option plans 16,100,206 9,252,665 Number of Shares Stock Purchase Plans Reserved for Issuance Available for Grant or Purchase 1997 stock plan for non-employee directors 536,295 375,245 (1) All available to be issued as stock options, but includes a sub-limit for all types of stock awards of 1,989,000 shares.
Performance Shares Transactions	Performance share transactions were as follows: To Settle in Cash To Settle in Shares Shares Weighted-Average Fair Value per Share Shares Weighted-Average Fair Value per Share Outstanding at January 1, 2018 650,689 $ 35.62 480,200 $ 19.81 Granted 81,626 32.67 88,500 33.03 Paid/Issued (77,262 ) 35.62 (34,500 ) 27.40 Converted from shares to cash 29,375 17.88 (29,375 ) 17.88 Canceled (14,125 ) 34.68 (14,125 ) 26.51 Outstanding at December 31, 2018 670,303 $ 19.89 490,700 $ 21.58 Total vested at December 31, 2018 564,686 $ 19.89 385,083 $ 18.95
Summary of Unvested Performance Shares	The summary of the status of our unvested performance shares to be settled in cash were as follows: Shares Weighted-Average Fair Value per Share Unvested at January 1, 2018 202,017 $ 35.62 Granted 81,626 32.67 Vested (163,901 ) 19.89 Canceled (14,125 ) 34.68 Unvested at December 31, 2018 105,617 $ 19.89

SHAREHOLDERS' EQUITY (Tables)

SHAREHOLDERS' EQUITY (Tables)	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Activity included in accumulated other comprehensive loss table	The following table represents the activity included in accumulated other comprehensive loss: Foreign Currency Translation Adjustment (net of taxes) Unrealized (Losses) Gains on Derivative Contracts (net of taxes) Pension and Other Postretirement Benefits (net of taxes) Accumulated Other Comprehensive Loss ($ in millions) Balance at January 1, 2016 $ (12.1 ) $ (6.9 ) $ (473.5 ) $ (492.5 ) Unrealized (losses) gains (22.4 ) 26.3 (61.0 ) (57.1 ) Reclassification adjustments of losses into income — 5.8 20.4 26.2 Tax benefit (provision) 10.4 (12.4 ) 15.4 13.4 Net change (12.0 ) 19.7 (25.2 ) (17.5 ) Balance at December 31, 2016 (24.1 ) 12.8 (498.7 ) (510.0 ) Unrealized gains (losses) 55.6 1.9 (27.3 ) 30.2 Reclassification adjustments of (gains) losses into income — (4.6 ) 26.9 22.3 Tax (provision) benefit (23.9 ) 1.0 (4.2 ) (27.1 ) Net change 31.7 (1.7 ) (4.6 ) 25.4 Balance at December 31, 2017 7.6 11.1 (503.3 ) (484.6 ) Unrealized losses (22.2 ) (1.1 ) (98.5 ) (121.8 ) Reclassification adjustments of (gains) losses into income — (14.3 ) 37.0 22.7 Tax benefit (provision) — 3.7 14.9 18.6 Net change (22.2 ) (11.7 ) (46.6 ) (80.5 ) Income tax reclassification adjustment 15.3 2.4 (103.6 ) (85.9 ) Balance at December 31, 2018 $ 0.7 $ 1.8 $ (653.5 ) $ (651.0 )

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	Years ended December 31, 2018 2017 2016 Sales: ($ in millions) Chlor Alkali Products and Vinyls $ 3,986.7 $ 3,500.8 $ 2,999.3 Epoxy 2,303.1 2,086.4 1,822.0 Winchester 656.3 681.2 729.3 Total sales $ 6,946.1 $ 6,268.4 $ 5,550.6 Income (loss) before taxes: Chlor Alkali Products and Vinyls $ 637.1 $ 405.8 $ 224.9 Epoxy 52.8 (11.8 ) 15.4 Winchester 38.4 72.4 120.9 Corporate/Other: Environmental income (expense) 103.7 (8.5 ) (9.2 ) Other corporate and unallocated costs (158.3 ) (112.4 ) (91.4 ) Restructuring charges (21.9 ) (37.6 ) (112.9 ) Acquisition-related costs (1.0 ) (12.8 ) (48.8 ) Other operating income 6.4 3.3 10.6 Interest expense (243.2 ) (217.4 ) (191.9 ) Interest income 1.6 1.8 3.4 Non-operating pension income 21.7 34.4 44.8 Income (loss) before taxes $ 437.3 $ 117.2 $ (34.2 ) Earnings (losses) of non-consolidated affiliates: Chlor Alkali Products and Vinyls $ (19.7 ) $ 1.8 $ 1.7 Depreciation and amortization expense: Chlor Alkali Products and Vinyls $ 473.1 $ 432.2 $ 418.1 Epoxy 102.4 94.3 90.0 Winchester 20.0 19.5 18.5 Corporate/Other 5.9 12.9 6.9 Total depreciation and amortization expense $ 601.4 $ 558.9 $ 533.5 Capital spending: Chlor Alkali Products and Vinyls $ 259.9 $ 209.5 $ 195.1 Epoxy 36.3 37.9 45.4 Winchester 14.7 22.5 19.5 Corporate/Other 74.3 24.4 18.0 Total capital spending $ 385.2 $ 294.3 $ 278.0 Segment assets include only those assets which are directly identifiable to an operating segment. Assets of the corporate/other segment include primarily such items as cash and cash equivalents, deferred taxes and other assets. December 31, 2018 2017 Assets: ($ in millions) Chlor Alkali Products and Vinyls $ 6,837.2 $ 7,008.0 Epoxy 1,521.9 1,597.1 Winchester 399.9 425.2 Corporate/Other 238.4 188.0 Total assets $ 8,997.4 $ 9,218.3 Investments—affiliated companies (at equity): Chlor Alkali Products and Vinyls $ 8.8 $ 28.5
Segment geographic data	Long-lived assets are attributed to geographic areas based on asset location and sales are attributed to geographic areas based on customer location. December 31, 2018 2017 Long-lived assets: ($ in millions) United States $ 3,147.6 $ 3,211.9 Foreign 334.5 363.9 Total long-lived assets $ 3,482.1 $ 3,575.8
Disaggregation of Revenue	Year Ended December 31, 2018 Chlor Alkali Products and Vinyls Epoxy Winchester Total Sales: ($ in millions) United States $ 2,610.7 $ 742.7 $ 591.0 $ 3,944.4 Europe 181.8 991.1 11.0 1,183.9 Other foreign 1,194.2 569.3 54.3 1,817.8 Total Sales $ 3,986.7 $ 2,303.1 $ 656.3 $ 6,946.1 Year Ended December 31, 2017 Chlor Alkali Products and Vinyls Epoxy Winchester Total Sales: ($ in millions) United States $ 2,294.4 $ 646.5 $ 615.2 $ 3,556.1 Europe 130.1 940.8 11.6 1,082.5 Other foreign 1,076.3 499.1 54.4 1,629.8 Total Sales $ 3,500.8 $ 2,086.4 $ 681.2 $ 6,268.4 Year Ended December 31, 2016 Chlor Alkali Products and Vinyls Epoxy Winchester Total Sales: ($ in millions) United States $ 2,161.3 $ 532.4 $ 661.5 $ 3,355.2 Europe 121.3 787.6 15.0 923.9 Other foreign 716.7 502.0 52.8 1,271.5 Total Sales $ 2,999.3 $ 1,822.0 $ 729.3 $ 5,550.6 Years ended December 31, 2018 2017 2016 Sales: ($ in millions) Chlor Alkali Products and Vinyls Caustic soda $ 2,198.6 $ 1,904.3 $ 1,479.3 Chlorine, chlorine derivatives and other co-products 1,788.1 1,596.5 1,520.0 Total Chlor Alkali Products and Vinyls 3,986.7 3,500.8 2,999.3 Epoxy Aromatics and allylics 1,145.7 1,051.1 844.4 Epoxy resins 1,157.4 1,035.3 977.6 Total Epoxy 2,303.1 2,086.4 1,822.0 Winchester Commercial 427.6 471.0 559.7 Military and law enforcement 228.7 210.2 169.6 Total Winchester 656.3 681.2 729.3 Total Sales $ 6,946.1 $ 6,268.4 $ 5,550.6

ENVIRONMENTAL (Tables)

ENVIRONMENTAL (Tables)	12 Months Ended
	Dec. 31, 2018
Environmental Remediation Obligations [Abstract]
Rollforward of environmental liabilities	Our liabilities for future environmental expenditures were as follows: December 31, 2018 2017 ($ in millions) Beginning balance $ 131.6 $ 137.3 Charges to income 7.3 10.3 Remedial and investigatory spending (13.0 ) (16.5 ) Foreign currency translation adjustments (0.3 ) 0.5 Ending balance $ 125.6 $ 131.6
Environmental Provisions Charged to Income Table	Environmental provisions (credited) charged to income, which are included in cost of goods sold, were as follows: Years ended December 31, 2018 2017 2016 ($ in millions) Provisions charged to income $ 7.3 $ 10.3 $ 9.2 Insurance recoveries for costs incurred and expensed (111.0 ) (1.8 ) — Environmental (income) expense $ (103.7 ) $ 8.5 $ 9.2

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contractual commitments under non-cancelable operating leases and purchase contracts	The following table summarizes our contractual commitments under non-cancelable operating leases and purchase contracts as of December 31, 2018 : Operating Leases Purchase Commitments ($ in millions) 2019 $ 82.2 $ 678.5 2020 61.4 642.5 2021 44.2 727.7 2022 31.8 725.0 2023 23.2 725.0 Thereafter 102.6 4,424.9 Total commitments $ 345.4 $ 7,923.6

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivative instruments	We had the following notional amounts of outstanding commodity contracts that were entered into to hedge forecasted purchases: December 31, 2018 2017 ($ in millions) Natural gas $ 58.4 $ 39.2 Other commodities 58.1 53.6 Total notional $ 116.5 $ 92.8
Summary of location and fair value of derivative instruments on condensed balance sheets	The following table summarizes the location and fair value of the derivative instruments on our consolidated balance sheets. The table disaggregates our net derivative assets and liabilities into gross components on a contract-by-contract basis before giving effect to master netting arrangements: December 31, 2018 2017 Asset Derivatives: ($ in millions) Other current assets Derivatives designated as hedging instruments: Interest rate contracts - gains $ 5.3 $ 6.9 Commodity contracts - gains — 11.4 Commodity contracts - losses — (0.1 ) Derivatives not designated as hedging instruments: Foreign exchange contracts - gains 0.9 2.0 Foreign exchange contracts - losses (0.5 ) (1.0 ) Total other current assets 5.7 19.2 Other assets Derivatives designated as hedging instruments: Interest rate contracts - gains — 3.6 Commodity contracts - gains 0.9 — Commodity contracts - losses (0.2 ) — Total other assets 0.7 3.6 Total Asset Derivatives (1) $ 6.4 $ 22.8 Liability Derivatives: Accrued liabilities Derivatives designated as hedging instruments: Commodity contracts - losses $ 4.9 $ 3.8 Commodity contracts - gains (1.9 ) — Derivatives not designated as hedging instruments: Foreign exchange contracts - losses 0.6 — Foreign exchange contracts - gains (0.1 ) — Total accrued liabilities 3.5 3.8 Other liabilities Derivatives designated as hedging instruments: Interest rate contracts - losses 33.7 28.1 Commodity contract - losses 0.5 — Commodity contract - gains (0.1 ) — Total other liabilities 34.1 28.1 Total Liability Derivatives (1) $ 37.6 $ 31.9 (1) Does not include the impact of cash collateral received from or provided to counterparties.
Summary of effects of derivative instruments on consolidated statements of operations	The following table summarizes the effects of derivative instruments on our consolidated statements of operations: Amount of (Loss) Gain Years Ended December 31, Location of (Loss) Gain 2018 2017 2016 Derivatives – Cash Flow Hedges ($ in millions) Recognized in other comprehensive loss: Commodity contracts ——— $ (4.8 ) $ (2.1 ) $ 16.7 Interest rate contracts ——— 3.7 4.0 9.6 $ (1.1 ) $ 1.9 $ 26.3 Reclassified from accumulated other comprehensive loss into income: Interest rate contracts Interest expense $ 8.9 $ 3.1 $ — Commodity contracts Cost of goods sold 5.4 1.5 (5.8 ) $ 14.3 $ 4.6 $ (5.8 ) Derivatives – Fair Value Hedges Interest rate contracts Interest expense $ (2.1 ) $ 3.0 $ 3.7 Derivatives Not Designated as Hedging Instruments Commodity contracts Cost of goods sold $ — $ — $ (0.4 ) Foreign exchange contracts Selling and administration (5.4 ) 1.8 (11.1 ) $ (5.4 ) $ 1.8 $ (11.5 )

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping [Table Text Block]	The following table summarizes the assets and liabilities measured at fair value in the consolidated balance sheets: Balance at December 31, 2018 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets ($ in millions) Interest rate swaps $ — $ 5.3 $ — $ 5.3 Commodity contracts — 0.7 — 0.7 Foreign exchange contracts — 0.4 — 0.4 Total Assets $ — $ 6.4 $ — $ 6.4 Liabilities Interest rate swaps $ — $ 33.7 $ — $ 33.7 Commodity contracts — 3.4 — 3.4 Foreign exchange contracts — 0.5 — 0.5 Total Liabilities $ — $ 37.6 $ — $ 37.6 Balance at December 31, 2017 Assets Interest rate swaps $ — $ 10.5 $ — $ 10.5 Commodity contracts — 11.3 — 11.3 Foreign exchange contracts — 1.0 — 1.0 Total Assets $ — $ 22.8 $ — $ 22.8 Liabilities Interest rate swaps $ — $ 28.1 $ — $ 28.1 Commodity contracts — 3.8 — 3.8 Total Liabilities $ — $ 31.9 $ — $ 31.9
Fair Value Of Debt Table [Table Text Block]	The following table summarizes the fair value measurements of debt and the actual debt recorded on our balance sheets: Fair Value Measurements Level 1 Level 2 Level 3 Total Amount recorded on balance sheets ($ in millions) Balance at December 31, 2018 $ — $ 3,137.2 $ 153.0 $ 3,290.2 $ 3,230.3 Balance at December 31, 2017 — 3,758.0 153.0 3,911.0 3,612.0

SUPPLEMENTAL GUARANTOR FINANC_2

SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2018
Supplemental Guarantor Financial Information [Abstract]
Supplemental Guarantor Financial Information Balance Sheets	CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Assets Current assets: Cash and cash equivalents $ 92.0 $ — $ 86.8 $ — $ 178.8 Receivables, net 99.7 — 676.6 — 776.3 Intercompany receivables — — 2,558.2 (2,558.2 ) — Income taxes receivable 2.6 — 3.3 — 5.9 Inventories, net 161.4 — 550.0 — 711.4 Other current assets 220.2 — 1.8 (187.0 ) 35.0 Total current assets 575.9 — 3,876.7 (2,745.2 ) 1,707.4 Property, plant and equipment, net 651.4 — 2,830.7 — 3,482.1 Investment in subsidiaries 6,943.3 4,286.9 — (11,230.2 ) — Deferred income taxes 7.3 — 27.4 (8.4 ) 26.3 Other assets 24.3 — 1,126.1 — 1,150.4 Long-term receivables—affiliates — 1,247.2 — (1,247.2 ) — Intangible assets, net 0.3 — 511.3 — 511.6 Goodwill — 966.3 1,153.3 — 2,119.6 Total assets $ 8,202.5 $ 6,500.4 $ 9,525.5 $ (15,231.0 ) $ 8,997.4 Liabilities and Shareholders’ Equity Current liabilities: Current installments of long-term debt $ 0.9 $ — $ 125.0 $ — $ 125.9 Accounts payable 90.1 — 549.4 (3.0 ) 636.5 Intercompany payables 2,558.2 — — (2,558.2 ) — Income taxes payable 3.9 — 18.7 — 22.6 Accrued liabilities 150.3 — 367.5 (184.5 ) 333.3 Total current liabilities 2,803.4 — 1,060.6 (2,745.7 ) 1,118.3 Long-term debt 1,357.5 1,746.9 — — 3,104.4 Accrued pension liability 439.1 — 235.2 — 674.3 Deferred income taxes — 6.0 521.3 (8.4 ) 518.9 Long-term payables—affiliates 469.6 — 777.6 (1,247.2 ) — Other liabilities 300.7 5.5 443.1 — 749.3 Total liabilities 5,370.3 1,758.4 3,037.8 (4,001.3 ) 6,165.2 Commitments and contingencies Shareholders’ equity: Common stock 165.3 — 14.6 (14.6 ) 165.3 Additional paid-in capital 2,247.4 4,125.7 4,808.2 (8,933.9 ) 2,247.4 Accumulated other comprehensive loss (651.0 ) — (6.9 ) 6.9 (651.0 ) Retained earnings 1,070.5 616.3 1,671.8 (2,288.1 ) 1,070.5 Total shareholders’ equity 2,832.2 4,742.0 6,487.7 (11,229.7 ) 2,832.2 Total liabilities and shareholders’ equity $ 8,202.5 $ 6,500.4 $ 9,525.5 $ (15,231.0 ) $ 8,997.4 CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2017 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Assets Current assets: Cash and cash equivalents $ 57.1 $ — $ 161.3 $ — $ 218.4 Receivables, net 95.6 — 637.6 — 733.2 Intercompany receivables — — 2,093.2 (2,093.2 ) — Income taxes receivable 11.7 — 6.3 (1.1 ) 16.9 Inventories, net 155.4 — 527.2 — 682.6 Other current assets 206.2 — 5.3 (163.4 ) 48.1 Total current assets 526.0 — 3,430.9 (2,257.7 ) 1,699.2 Property, plant and equipment, net 544.4 — 3,031.4 — 3,575.8 Investment in subsidiaries 6,680.4 4,092.3 — (10,772.7 ) — Deferred income taxes 38.1 — 34.5 (36.2 ) 36.4 Other assets 45.9 — 1,162.5 — 1,208.4 Long-term receivables—affiliates — 2,137.8 — (2,137.8 ) — Intangible assets, net 0.3 — 578.2 — 578.5 Goodwill — 966.3 1,153.7 — 2,120.0 Total assets $ 7,835.1 $ 7,196.4 $ 9,391.2 $ (15,204.4 ) $ 9,218.3 Liabilities and Shareholders’ Equity Current liabilities: Current installments of long-term debt $ 0.7 $ — $ — $ — $ 0.7 Accounts payable 83.2 — 590.0 (3.4 ) 669.8 Intercompany payables 2,093.2 — — (2,093.2 ) — Income taxes payable — — 10.5 (1.1 ) 9.4 Accrued liabilities 117.7 — 318.1 (161.4 ) 274.4 Total current liabilities 2,294.8 — 918.6 (2,259.1 ) 954.3 Long-term debt 839.4 2,522.2 249.7 — 3,611.3 Accrued pension liability 406.7 — 229.2 — 635.9 Deferred income taxes — 3.0 544.4 (36.2 ) 511.2 Long-term payables—affiliates 1,250.0 — 887.8 (2,137.8 ) — Other liabilities 290.5 5.6 455.8 — 751.9 Total liabilities 5,081.4 2,530.8 3,285.5 (4,433.1 ) 6,464.6 Commitments and contingencies Shareholders’ equity: Common stock 167.1 — 14.6 (14.6 ) 167.1 Additional paid-in capital 2,280.9 4,125.7 4,808.2 (8,933.9 ) 2,280.9 Accumulated other comprehensive loss (484.6 ) — (4.6 ) 4.6 (484.6 ) Retained earnings 790.3 539.9 1,287.5 (1,827.4 ) 790.3 Total shareholders’ equity 2,753.7 4,665.6 6,105.7 (10,771.3 ) 2,753.7 Total liabilities and shareholders’ equity $ 7,835.1 $ 7,196.4 $ 9,391.2 $ (15,204.4 ) $ 9,218.3
Supplemental Guarantor Financial Information Statement of Operations	CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2018 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Sales $ 1,423.8 $ — $ 5,937.0 $ (414.7 ) $ 6,946.1 Operating expenses: Cost of goods sold 1,153.1 — 5,083.7 (414.7 ) 5,822.1 Selling and administration 206.0 — 224.6 — 430.6 Restructuring charges — — 21.9 — 21.9 Acquisition-related costs 1.0 — — — 1.0 Other operating (loss) income (3.0 ) — 9.4 — 6.4 Operating income 60.7 — 616.2 — 676.9 Losses of non-consolidated affiliates (19.7 ) — — — (19.7 ) Equity income in subsidiaries 310.7 289.6 — (600.3 ) — Interest expense 68.6 153.3 26.9 (5.6 ) 243.2 Interest income 5.8 — 1.4 (5.6 ) 1.6 Non-operating pension income (expense) 26.6 — (4.9 ) — 21.7 Income before taxes 315.5 136.3 585.8 (600.3 ) 437.3 Income tax (benefit) provision (12.4 ) (35.1 ) 156.9 — 109.4 Net income $ 327.9 $ 171.4 $ 428.9 $ (600.3 ) $ 327.9 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2017 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Sales $ 1,330.3 $ — $ 5,344.9 $ (406.8 ) $ 6,268.4 Operating expenses: Cost of goods sold 1,195.5 — 4,766.2 (406.8 ) 5,554.9 Selling and administration 157.0 — 212.8 — 369.8 Restructuring charges 1.7 — 35.9 — 37.6 Acquisition-related costs 12.8 — — — 12.8 Other operating (loss) income (11.1 ) — 14.4 — 3.3 Operating (loss) income (47.8 ) — 344.4 — 296.6 Earnings of non-consolidated affiliates 1.8 — — — 1.8 Equity income in subsidiaries 638.4 357.6 — (996.0 ) — Interest expense 44.5 165.8 13.0 (5.9 ) 217.4 Interest income 6.3 — 1.4 (5.9 ) 1.8 Non-operating pension income (expense) 38.5 — (4.1 ) — 34.4 Income before taxes 592.7 191.8 328.7 (996.0 ) 117.2 Income tax provision (benefit) 43.2 (310.0 ) (165.5 ) — (432.3 ) Net income $ 549.5 $ 501.8 $ 494.2 $ (996.0 ) $ 549.5 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2016 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Sales $ 1,321.3 $ — $ 4,720.2 $ (490.9 ) $ 5,550.6 Operating expenses: Cost of goods sold 1,153.0 — 4,282.4 (490.9 ) 4,944.5 Selling and administration 162.1 — 185.1 — 347.2 Restructuring charges 0.8 — 112.1 — 112.9 Acquisition-related costs 47.4 — 1.4 — 48.8 Other operating (loss) income (2.2 ) — 12.8 — 10.6 Operating (loss) income (44.2 ) — 152.0 — 107.8 Earnings of non-consolidated affiliates 1.7 — — — 1.7 Equity income in subsidiaries 16.2 139.0 — (155.2 ) — Interest expense 38.8 153.9 4.7 (5.5 ) 191.9 Interest income 4.7 — 4.2 (5.5 ) 3.4 Non-operating pension income (expense) 48.3 — (3.5 ) — 44.8 Income (loss) before taxes (12.1 ) (14.9 ) 148.0 (155.2 ) (34.2 ) Income tax (benefit) provision (8.2 ) (57.6 ) 35.5 — (30.3 ) Net (loss) income $ (3.9 ) $ 42.7 $ 112.5 $ (155.2 ) $ (3.9 )
Supplemental Guarantor Financial Information Statements Of Comprehensive Income	CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) Year Ended December 31, 2018 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net income $ 327.9 $ 171.4 $ 428.9 $ (600.3 ) $ 327.9 Other comprehensive loss, net of tax: Foreign currency translation adjustments, net — — (22.2 ) — (22.2 ) Unrealized losses on derivative contracts, net (11.7 ) — — — (11.7 ) Pension and postretirement liability adjustments, net (69.6 ) — (5.3 ) — (74.9 ) Amortization of prior service costs and actuarial losses, net 26.3 — 2.0 — 28.3 Total other comprehensive loss, net of tax (55.0 ) — (25.5 ) — (80.5 ) Comprehensive income $ 272.9 $ 171.4 $ 403.4 $ (600.3 ) $ 247.4 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) Year Ended December 31, 2017 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net income $ 549.5 $ 501.8 $ 494.2 $ (996.0 ) $ 549.5 Other comprehensive income, net of tax: Foreign currency translation adjustments, net — — 31.7 — 31.7 Unrealized losses on derivative contracts, net (1.7 ) — — — (1.7 ) Pension and postretirement liability adjustments, net (12.3 ) — (9.3 ) — (21.6 ) Amortization of prior service costs and actuarial losses, net 15.3 — 1.7 — 17.0 Total other comprehensive income, net of tax 1.3 — 24.1 — 25.4 Comprehensive income $ 550.8 $ 501.8 $ 518.3 $ (996.0 ) $ 574.9 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) Year Ended December 31, 2016 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net (loss) income $ (3.9 ) $ 42.7 $ 112.5 $ (155.2 ) $ (3.9 ) Other comprehensive income (loss), net of tax: Foreign currency translation adjustments, net — — (12.0 ) — (12.0 ) Unrealized gains on derivative contracts, net 19.7 — — — 19.7 Pension and postretirement liability adjustments, net (25.3 ) — (12.2 ) — (37.5 ) Amortization of prior service costs and actuarial losses, net 10.9 — 1.4 — 12.3 Total other comprehensive income (loss), net of tax 5.3 — (22.8 ) — (17.5 ) Comprehensive income (loss) $ 1.4 $ 42.7 $ 89.7 $ (155.2 ) $ (21.4 )
Supplemental Guarantor Financial Information Statements Of Cash Flows	CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2018 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net operating activities $ 529.8 $ — $ 378.0 $ — $ 907.8 Investing Activities Capital expenditures (149.8 ) — (235.4 ) — (385.2 ) Proceeds from disposition of property, plant and equipment — — 2.9 — 2.9 Distributions from consolidated subsidiaries, net 95.0 95.0 — (190.0 ) — Net investing activities (54.8 ) 95.0 (232.5 ) (190.0 ) (382.3 ) Financing Activities Long-term debt: Borrowings 550.0 — 20.0 — 570.0 Repayments (21.0 ) (780.4 ) (144.7 ) — (946.1 ) Common stock repurchased and retired (50.0 ) — — — (50.0 ) Stock options exercised 3.4 — — — 3.4 Dividends paid (133.6 ) (95.0 ) (95.0 ) 190.0 (133.6 ) Debt issuance costs (8.5 ) — — — (8.5 ) Intercompany financing activities (780.4 ) 780.4 — — — Net financing activities (440.1 ) (95.0 ) (219.7 ) 190.0 (564.8 ) Effect of exchange rate changes on cash and cash equivalents — — (0.3 ) — (0.3 ) Net increase (decrease) in cash and cash equivalents 34.9 — (74.5 ) — (39.6 ) Cash and cash equivalents, beginning of year 57.1 — 161.3 — 218.4 Cash and cash equivalents, end of year $ 92.0 $ — $ 86.8 $ — $ 178.8 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2017 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net operating activities $ 472.0 $ — $ 176.8 $ — $ 648.8 Investing Activities Capital expenditures (89.1 ) — (205.2 ) — (294.3 ) Payments under long-term supply contracts — — (209.4 ) — (209.4 ) Proceeds from disposition of property, plant and equipment — — 5.2 — 5.2 Distribution from consolidated subsidiaries, net 2.7 — — (2.7 ) — Net investing activities (86.4 ) — (409.4 ) (2.7 ) (498.5 ) Financing Activities Long-term debt: Borrowings 620.0 1,375.0 40.5 — 2,035.5 Repayments (690.8 ) (1,334.1 ) (13.0 ) — (2,037.9 ) Stock options exercised 29.8 — — — 29.8 Dividends paid (133.0 ) — (2.7 ) 2.7 (133.0 ) Debt issuance costs (8.3 ) (2.9 ) — — (11.2 ) Intercompany financing activities (171.4 ) (38.0 ) 209.4 — — Net financing activities (353.7 ) — 234.2 2.7 (116.8 ) Effect of exchange rate changes on cash and cash equivalents — — 0.4 — 0.4 Net increase in cash and cash equivalents 31.9 — 2.0 — 33.9 Cash and cash equivalents, beginning of year 25.2 — 159.3 — 184.5 Cash and cash equivalents, end of year $ 57.1 $ — $ 161.3 $ — $ 218.4 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2016 (In millions) Parent Guarantor Issuer Subsidiary Eliminations Total Net operating activities $ 702.6 $ — $ (99.4 ) $ — $ 603.2 Investing Activities Capital expenditures (65.7 ) — (212.3 ) — (278.0 ) Business acquired and related transactions, net of cash acquired (69.5 ) — — — (69.5 ) Payments under long-term supply contracts — — (175.7 ) — (175.7 ) Proceeds from sale/leaseback of equipment — — 40.4 — 40.4 Proceeds from disposition of property, plant and equipment 0.2 — 0.3 — 0.5 Proceeds from disposition of affiliated companies 8.8 — — — 8.8 Net investing activities (126.2 ) — (347.3 ) — (473.5 ) Financing Activities Long-term debt: Borrowings — — 230.0 — 230.0 Repayments (335.6 ) (67.5 ) (32.2 ) — (435.3 ) Stock options exercised 0.5 — — — 0.5 Excess tax benefits from stock-based compensation 0.4 — — — 0.4 Dividends paid (132.1 ) — — — (132.1 ) Debt issuance costs — (1.0 ) — — (1.0 ) Intercompany financing activities (203.8 ) 68.5 135.3 — — Net financing activities (670.6 ) — 333.1 — (337.5 ) Effect of exchange rate changes on cash and cash equivalents — — 0.3 — 0.3 Net decrease in cash and cash equivalents (94.2 ) — (113.3 ) — (207.5 ) Cash and cash equivalents, beginning of year 119.4 — 272.6 — 392.0 Cash and cash equivalents, end of year $ 25.2 $ — $ 159.3 $ — $ 184.5

OTHER FINANCIAL DATA (Tables)

OTHER FINANCIAL DATA (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Quarterly Data (Unaudited)	Quarterly Data (Unaudited) ($ in millions, except per share data) 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Year Sales $ 1,710.3 $ 1,728.4 $ 1,872.4 $ 1,635.0 $ 6,946.1 Cost of goods sold 1,528.7 1,460.7 1,441.7 1,391.0 5,822.1 Net income 20.9 58.6 195.1 53.3 327.9 Net income per common share: Basic 0.13 0.35 1.17 0.32 1.97 Diluted 0.12 0.35 1.16 0.32 1.95 Common dividends per share 0.20 0.20 0.20 0.20 0.80 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Year Sales $ 1,567.1 $ 1,526.5 $ 1,554.9 $ 1,619.9 $ 6,268.4 Cost of goods sold 1,397.5 1,407.9 1,349.3 1,400.2 5,554.9 Net income (loss) 13.4 (5.9 ) 52.7 489.3 549.5 Net income (loss) per common share: Basic 0.08 (0.04 ) 0.32 2.93 3.31 Diluted 0.08 (0.04 ) 0.31 2.89 3.26 Common dividends per share 0.20 0.20 0.20 0.20 0.80

ACCOUNTING POLICIES (Details)

ACCOUNTING POLICIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Gains on insurance recoveries	$ 8	$ 0	$ 11
Loss on sale of land	1.7
Gain on disposition of former manufacturing facility		3.3
Short-term investments	0	0
Asset retirement obligation non-current portion	49.6	43.8
Asset retirement obligation revision of estimate	10.9	4.5
Goodwill impairment charge	0	0	0
Finite-lived intangible asset impairment charge	$ 0	$ 0	$ 0
Average remaining life expectancy of the inactive participants in the defined benefit pension plan (in years)	18 years	19 years

ACCOUNTING POLICIES (Details 1)

ACCOUNTING POLICIES (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Component of Operating Income [Abstract]
Gains (losses) on disposition of property, plant and equipment, net	$ (2)	$ 3.1	$ (0.7)
Gains on insurance recoveries	8	0	11
Other	0.4	0.2	0.3
Other operating income	$ 6.4	$ 3.3	$ 10.6

ACCOUNTING POLICIES (Details 2)

ACCOUNTING POLICIES (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Asset retirement obligation [Roll Forward]
Beginning balance	$ 54.3	$ 55.4
Accretion	3.2	3
Spending	(8)	(8.8)
Foreign currency translation adjustments	(0.2)	0.2
Adjustments	10.9	4.5
Ending balance	$ 60.2	$ 54.3

ACCOUNTING POLICIES (Details 3)

ACCOUNTING POLICIES (Details 3) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted vesting period (in years)	3 years
Black-Sholes assumptions [Abstract]
Dividend yield	2.43%	2.69%	6.09%
Risk-free interest rate	2.72%	2.06%	1.35%
Expected volatility	32.00%	34.00%	32.00%
Expected life (years)	6 years	6 years	6 years
Weighted-average grant fair value (per option) (in dollars)	$ 8.89	$ 7.78	$ 1.90
Weighted-average exercise price (in dollars)	$ 32.94	$ 29.82	$ 13.14
Shares granted (in shares)	927,000	1,621,000	1,670,400
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted vesting period (in years)	3 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted vesting period (in years)	1 year

RECENT ACCOUNTING PRONOUNCEME_2

RECENT ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Standards Update 2018-05
New Accounting Pronouncements or Change in Accounting Principle
U.S. Tax Cuts and Jobs Act Provisional Benefit		$ 437.9
2017 U.S. Tax Cuts and Jobs Act Benefit	$ 3.9
2017 U.S. Tax Cuts and Jobs Act Expense	0.1
Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle
Income Tax Accounting Standard Adoption	(85.9)
Minimum | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle
New Accounting Pronouncement, Cumulative Effect of Change on Retained Earnings	10
Maximum | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle
New Accounting Pronouncement, Cumulative Effect of Change on Retained Earnings	15
Cost of Goods Sold | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle
New Accounting Pronouncement, Quantification of Effect of Adoption		15.3	$ 20.8
Selling and Administration Expenses | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle
New Accounting Pronouncement, Quantification of Effect of Adoption		$ 19.1	$ 24
Right-of-use Assets and Lease Liabilities | Minimum | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle
New Accounting Pronouncement, Quantification of Effect of Adoption	275
Right-of-use Assets and Lease Liabilities | Maximum | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle
New Accounting Pronouncement, Quantification of Effect of Adoption	$ 325

ACQUISITION (Details)

ACQUISITION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Combinations [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired	$ 0	$ 0	$ 69.5
Acquisition-related costs	$ 1	$ 12.8	$ 48.8

RESTRUCTURING CHARGES (Details)

RESTRUCTURING CHARGES (Details) $ in Millions	1 Months Ended	12 Months Ended			33 Months Ended	49 Months Ended	98 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2018USD ($)	Mar. 21, 2016T	Dec. 31, 2015USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 21.9	$ 37.6	$ 112.9			$ 209.1
Restructuring and Related Cost, Incurred Cost							112.2
Restructuring Reserve, Settled without Cash							88.7
Accrued Restructuring Costs	$ 8.2	8.2	5.1	12.7	$ 8.2	$ 8.2	8.2		$ 6.7
Geelong | Winchester
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4.1
Additional restructuring and related expected cost	1	1			1	1	1
Capacity Reductions | Chlor Alkali Products and Vinyls
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		15.7	32.6	111.3	159.7
Additional restructuring and related expected cost	10	10			10	10	10
Becancour | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		2.1	3.3	0.8		18.2
Additional restructuring and related expected cost	$ 1	$ 1			$ 1	$ 1	1
Oxford | Winchester
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 1.7	$ 0.8			$ 27.1

RESTRUCTURING CHARGES (Details

RESTRUCTURING CHARGES (Details 1) - USD ($) $ in Millions	12 Months Ended			98 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 8.2	$ 5.1	$ 12.7	$ 8.2	$ 6.7
Restructuring charges	21.9	37.6	112.9	209.1
Amounts utilized	(18.8)	(45.2)	(106.9)
Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	1.5	1.8	3.4	1.5	4.6
Restructuring charges	1.7	2	5.1	24.6
Amounts utilized	(2)	(3.6)	(6.3)
Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	6	3.3	7.5	6	2.1
Restructuring charges	5.6	22.1	13.6	46.5
Amounts utilized	(2.9)	(26.3)	(8.2)
Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	0	0	0	0
Restructuring charges	0	0.3	2.1	7.7
Amounts utilized	0	(0.3)	(2.1)
Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0.7	0	1.8	0.7	0
Restructuring charges	12	11.7	15.5	42
Amounts utilized	(11.3)	(13.5)	(13.7)
Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	0	0	0	$ 0
Restructuring charges	2.6	1.5	76.6	$ 84.2
Amounts utilized	$ (2.6)	$ (1.5)	$ (76.6)

RESTRUCTURING CHARGES (Detail_2

RESTRUCTURING CHARGES (Details 2) - USD ($) $ in Millions	1 Months Ended	12 Months Ended			33 Months Ended	49 Months Ended	98 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 21.9	$ 37.6	$ 112.9			$ 209.1
Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges		2.6	1.5	76.6			84.2
Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1.7	2	5.1			24.6
Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		12	11.7	15.5			42
Pension and other postretirement benefits curtailment
Restructuring Cost and Reserve [Line Items]
Restructuring charges							4.1
Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0	0.3	2.1			7.7
Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		5.6	22.1	13.6			46.5
Capacity Reductions | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		15.7	32.6	111.3	$ 159.7
Capacity Reductions | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges					78.1
Capacity Reductions | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges					5.9
Capacity Reductions | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges					33.8
Capacity Reductions | Chlor Alkali Products and Vinyls | Pension and other postretirement benefits curtailment
Restructuring Cost and Reserve [Line Items]
Restructuring charges					0
Capacity Reductions | Chlor Alkali Products and Vinyls | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges					1.7
Capacity Reductions | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges					$ 40.2
Becancour | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 2.1	3.3	0.8		$ 18.2
Becancour | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges						3.5
Becancour | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						2.7
Becancour | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						5.9
Becancour | Chlor Alkali Products and Vinyls | Pension and other postretirement benefits curtailment
Restructuring Cost and Reserve [Line Items]
Restructuring charges						0
Becancour | Chlor Alkali Products and Vinyls | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						0
Becancour | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						$ 6.1
Geelong | Winchester
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4.1
Geelong | Winchester | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2.6
Geelong | Winchester | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1.3
Geelong | Winchester | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Geelong | Winchester | Pension and other postretirement benefits curtailment
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Geelong | Winchester | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Geelong | Winchester | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0.2
Oxford | Winchester
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 1.7	$ 0.8			27.1
Oxford | Winchester | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges							0
Oxford | Winchester | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges							14.7
Oxford | Winchester | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges							2.3
Oxford | Winchester | Pension and other postretirement benefits curtailment
Restructuring Cost and Reserve [Line Items]
Restructuring charges							4.1
Oxford | Winchester | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges							6
Oxford | Winchester | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges							$ 0

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income (loss)	$ 53.3	$ 195.1	$ 58.6	$ 20.9	$ 489.3	$ 52.7	$ (5.9)	$ 13.4	$ 327.9	$ 549.5	$ (3.9)
Basic shares (in shares)									166.8	166.2	165.2
Earnings per Share, Basic [Abstract]
Basic net income (loss) per share (in dollars per share)	$ 0.32	$ 1.17	$ 0.35	$ 0.13	$ 2.93	$ 0.32	$ (0.04)	$ 0.08	$ 1.97	$ 3.31	$ (0.02)
Earnings per Share, Diluted [Abstract]
Basic shares (in shares)									166.8	166.2	165.2
Stock-based compensation (in shares)									1.6	2.3	0
Diluted shares (in shares)									168.4	168.5	165.2
Diluted net income (loss) per share (in dollars per share)	$ 0.32	$ 1.16	$ 0.35	$ 0.12	$ 2.89	$ 0.31	$ (0.04)	$ 0.08	$ 1.95	$ 3.26	$ (0.02)
Antidilutive shares excluded from the computation of earnings per share (in shares)									2.4	1.6	6.5

ACCOUNTS RECEIVABLES (Details)

ACCOUNTS RECEIVABLES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Receivables Financing Agreement Term (in years)	3 years
Receivables Financing Agreement Maximum Borrowing Capacity			$ 250
Receivables Financing Agreement Collateral	$ 360.4	$ 340.9
Receivables Financing Agreement	125	249.7
Receivables Financing Agreement Available Borrowing Capacity	125
AR Facilities, Maximum Outstanding Sales		315
AR Facilities, Amount Outstanding to be Serviced	132.4	182.3	126.1
AR Facilities, Gross receivables sold	1,372.3	1,655.2
AR Facilities, Payments received from customers on sold accounts	(1,422.2)	(1,599)
AR Facilities, Interest Expense	4.3	3.7	$ 1.1
AR Facilities, Recourse Liability	0
Other Receivables	$ 58	$ 105.5

ALLOWANCE FOR DOUBTFUL ACCOUN_3

ALLOWANCE FOR DOUBTFUL ACCOUNTS RECEIVABLES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	$ 12.3	$ 10.1
Provisions charged	1.7	1.8
Write-offs, net of recoveries	(0.7)	(0.1)
Foreign currency translation adjustments	(0.4)	0.5
Balance at end of year	$ 12.9	$ 12.3

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Supplies	$ 66.4	$ 66.1
Raw materials	66.7	75.3
Work in process	139.6	127.8
Finished goods	488.5	462.6
Inventories, excluding LIFO reserve	761.2	731.8
LIFO reserve	(49.8)	(49.2)
Inventories, net	$ 711.4	$ 682.6
Percentage of inventory using the last-in, first-out (LIFO) method of inventory accounting	55.00%	55.00%

OTHER ASSETS (Details)

OTHER ASSETS (Details) - USD ($) $ in Millions	Feb. 07, 2019	Jan. 01, 2019	Oct. 05, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Assets [Abstract]
Supply contracts				$ 1,099.5	$ 1,137.1
Investments in non-consolidated affiliates				8.8	28.5
Other				42.1	42.8
Other assets				1,150.4	1,208.4
Schedule of Equity Method Investments [Line Items]
Earnings (losses) of non-consolidated affiliates				(19.7)	1.8	$ 1.7
Business Combination, Separately Recognized Transactions [Line Items]
2017 Supply Contract Payment					209.4
Long-term Purchase Commitment [Line Items]
2020 Supply Contract Payment					389.2
2020 Supply Contract Payment Total Accretion					51.8
2020 Supply Contract Accretion Expense				16	3.9
Payments under long-term supply contract				0	$ 209.4	175.7
Supply Contract Weighted-average Useful Life					20 years
Supply Contract Amortization				37.6	$ 28.2	21.5
Supply Contract Amortization Expense Next Twelve Months				38
Supply Contract Amortization Expense, Year 2				38
Supply Contract Amortization Expense, Year 3				60
Supply Contract Amortization Expense, Year 4				60
Supply Contract Amortization Expense, Year 5				60
Bay Gas
Schedule of Equity Method Investments [Line Items]
Bay Gas non-cash impairment charge				21.5
Bay Gas Olin ownership percentage					9.10%
Bay Gas Sempra ownership percentage					90.90%
Bay Gas Equity Investment Sale | Bay Gas
Subsequent Event [Line Items]
Bay Gas equity investment sale proceeds		$ 20
Bay Gas equity investment sale gain	$ 11
Chlor Alkali Products and Vinyls
Other Assets [Abstract]
Investments in non-consolidated affiliates				8.8	$ 28.5
Chlor Alkali Products and Vinyls | Bay Gas
Schedule of Equity Method Investments [Line Items]
Earnings (losses) of non-consolidated affiliates				(19.7)	$ 1.8	$ 1.7
Minimum
Long-term Purchase Commitment [Line Items]
2020 Supply Contract Payment				440
Maximum
Long-term Purchase Commitment [Line Items]
2020 Supply Contract Payment				$ 465
Blue Cube Business
Business Combination, Separately Recognized Transactions [Line Items]
Up-front payments under the ethylene agreements			$ 433.5
Fair value of up-front ethylene payment			$ 416.1

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 6,263.1	$ 5,908.9
Accumulated depreciation	(2,781)	(2,333.1)
Property, plant and equipment, net	$ 3,482.1	3,575.8
Weighted Average Useful Life of Machinery and Equipment	11 years
Depreciation expense	$ 497.8	465.1	$ 435.7
Interest capitalized	6	3	1.9
Change in Capital Expenditures Incurred but Not Yet Paid	(25.5)	(0.5)	(29.9)
Proceeds from sale/leaseback of equipment	0		$ 40.4
Land and improvements to land
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 276.9	281.7
Land and improvements to land | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	10 years
Land and improvements to land | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	20 years
Building and building equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 387.6	382.4
Building and building equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	10 years
Building and building equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	30 years
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 5,252	5,028.4
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	3 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life (in years)	20 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 5.2	3.9
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 341.4	$ 212.5

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill	$ 2,119.6	$ 2,120	$ 2,118
Foreign currency translation adjustment	(0.4)	2
Chlor Alkali Products and Vinyls
Goodwill [Line Items]
Goodwill	1,832.6	1,832.9	1,831.3
Foreign currency translation adjustment	(0.3)	1.6
Epoxy
Goodwill [Line Items]
Goodwill	287	287.1	$ 286.7
Foreign currency translation adjustment	$ (0.1)	$ 0.4

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	$ 768.3	$ 775
Finite-Lived Intangible Assets, Accumulated Amortization	(256.7)	(196.5)
Finite-Lived Intangible Assets, Net	511.6	578.5
Customers, customer contracts and relationships
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	675.2	679.5
Finite-Lived Intangible Assets, Accumulated Amortization	(211.9)	(163.6)
Finite-Lived Intangible Assets, Net	463.3	515.9
Trade name
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	7	7.1
Finite-Lived Intangible Assets, Accumulated Amortization	(4.6)	(3.2)
Finite-Lived Intangible Assets, Net	2.4	3.9
Acquired technology
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	85.4	86.1
Finite-Lived Intangible Assets, Accumulated Amortization	(39.6)	(27.7)
Finite-Lived Intangible Assets, Net	45.8	58.4
Other
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	0.7	2.3
Finite-Lived Intangible Assets, Accumulated Amortization	(0.6)	(2)
Finite-Lived Intangible Assets, Net	$ 0.1	$ 0.3
Minimum | Customers, customer contracts and relationships
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Minimum | Trade name
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Minimum | Acquired technology
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Minimum | Other
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Maximum | Customers, customer contracts and relationships
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
Maximum | Trade name
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Maximum | Acquired technology
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Maximum | Other
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Amortization	$ 62.8	$ 62.8	$ 73.8
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	63
Finite-Lived Intangible Assets, Amortization Expense, Year Two	63
Finite-Lived Intangible Assets, Amortization Expense, Year Three	61
Finite-Lived Intangible Assets, Amortization Expense, Year Four	54
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 35
Trade name | K.A. Steel Chemicals Inc.
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Asset, Useful Life			1 year
Amortization			$ 10.9

DEBT (Details)

DEBT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 19, 2018	Mar. 09, 2017	Oct. 31, 2016	Jun. 30, 2016	Oct. 05, 2015	Jun. 23, 2015	Dec. 22, 1997
Debt Instrument [Line Items]
Term Loan Facility					$ 1,375				$ 1,350
Senior Credit Facility Term (in years)	5 years
Senior Credit Facility					1,975				1,850
Senior Revolving Credit Facility					600				$ 500
Senior Revolving Credit Facility, Available Borrowing Amount	$ 596.5
Senior Revolving Credit Facility, Letters of Credit Outstanding Amount	$ 3.5
Senior Revolving Credit Facility, Subfacility Amount					$ 100
Annual Required Principal Payment (Percent) in Years 1 and 2					5.00%
Annual Required Principal Payment (Percent) in Year 3					7.50%
Annual Required Principal Payment (Percent) in Years 4 and 5					10.00%
2027 Senior Notes					$ 500
Receivables Financing Agreement Term (in years)	3 years
Receivables Financing Agreement Maximum Borrowing Capacity			$ 250
Receivables Financing Agreement Collateral	$ 360.4	$ 340.9
Receivables Financing Agreement	125	249.7
Receivables Financing Agreement Available Borrowing Capacity	125
Receivables Financing Agreement Amount Borrowed		40
Sumitomo Credit Facility								$ 800
Debt issuance costs	8.5	11.2	1
Total Letters of Credit Outstanding	74.7
Expected maturities of long-term debt [Abstract]
2,019	125.9
2,020	1.8
2,021	0.5
2,022	743.4
2,023	720.3
Thereafter	1,706.2
Swap Amount	116.5	92.8
Derivative Liability, Fair Value, Gross Liability	37.6	31.9
Reduction in interest expense due to interest rate swaps	6.8	$ 6.1	3.7
2030 Notes
Debt Instrument [Line Items]
2030 Notes Debt Issuance Proceeds	$ 550
Interest rate	5.00%	0.00%		5.00%
Sumitomo Credit Facility
Debt Instrument [Line Items]
Debt Repayments		$ 590	210
Write-off of Unamortized Deferred Debt Issuance Costs		$ 1.5
2023 Notes
Debt Instrument [Line Items]
Interest rate	9.75%	9.75%						9.75%
2023 Senior Notes								$ 720
2025 Notes
Debt Instrument [Line Items]
Interest rate	10.00%	10.00%						10.00%
2025 Senior Notes								$ 500
Senior Credit Facility
Debt Instrument [Line Items]
Write-off of Unamortized Deferred Debt Issuance Costs	$ 2.6	$ 1.2
Term Loan Facility
Debt Instrument [Line Items]
Interest rate	4.02%	3.57%
Debt Repayments	$ 550	$ 1,282.5
Term Loan Amortization Payable, Amount Paid		$ 51.6	67.5
2027 Notes
Debt Instrument [Line Items]
Interest rate	5.125%	5.125%			5.125%
Notes payable due 2016
Debt Instrument [Line Items]
Interest rate							6.75%
Debt Repayments			125
SunBelt Notes
Debt Instrument [Line Items]
Debt Repayments		$ 12.2	12.2
Guaranteed Senior Secured Notes due 2017, Series O
Debt Instrument [Line Items]
Face amount of senior secured notes										$ 97.5
Guaranteed Senior Secured Notes due 2017, Series G
Debt Instrument [Line Items]
Face amount of senior secured notes										$ 97.5
SunBelt | SunBelt Notes
Debt Instrument [Line Items]
Interest rate										7.23%
Fixed Interest Rate Swaps $1,100M (Tranche 1)
Expected maturities of long-term debt [Abstract]
Swap Amount							$ 1,100
Fixed Interest Rate Swaps $900M (Tranche 2)
Expected maturities of long-term debt [Abstract]
Swap Amount							900
Fixed Interest Rate Swaps $400M (Tranche 3)
Expected maturities of long-term debt [Abstract]
Swap Amount							400
Interest Rate Contract Gains
Expected maturities of long-term debt [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 5.3
Interest Rate Swaps Designated As Fair Value Hedges
Expected maturities of long-term debt [Abstract]
Swap Amount	500	500				$ 250	$ 250
Derivative Liability, Fair Value, Gross Liability	33.7
Derivative, Gain (Loss) on Derivative, Net	$ (2.1)	$ 2.9	$ 2.6

DEBT (Details 1)

DEBT (Details 1) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 19, 2018	Dec. 31, 2017	Mar. 09, 2017	Oct. 05, 2015
Debt Instrument [Line Items]
Notes payable	$ 3,298.1		$ 3,672.7
Receivables Financing Agreement	125		249.7
Capital lease obligations	4.2		3.7
Deferred debt issuance costs	(34.1)		(32.6)
Interest rate swaps	(33.7)		(28.1)
Total debt	3,230.3		3,612
Current installments of long-term debt	125.9		0.7
Total long-term debt	3,104.4		3,611.3
Term Loan Facility
Debt Instrument [Line Items]
Notes payable	$ 543		$ 1,323.4
Interest rate	4.02%		3.57%
Variable-Rate Recovery Zone Bonds
Debt Instrument [Line Items]
Notes payable	$ 103		$ 103
Interest rate	3.67%		3.27%
Variable-Rate Go Zone Bonds
Debt Instrument [Line Items]
Notes payable	$ 50		$ 50
Interest rate	3.67%		3.27%
Industrial Development and Environmental Improvement Obligations
Debt Instrument [Line Items]
Notes payable	$ 2.9		$ 2.9
Interest rate	2.52%		1.27%
2023 Notes
Debt Instrument [Line Items]
Notes payable	$ 720		$ 720
Interest rate	9.75%		9.75%		9.75%
2025 Notes
Debt Instrument [Line Items]
Notes payable	$ 500		$ 500
Interest rate	10.00%		10.00%		10.00%
2022 Notes
Debt Instrument [Line Items]
Notes payable	$ 200		$ 200
Interest rate	5.50%		5.50%
2027 Notes
Debt Instrument [Line Items]
Notes payable	$ 500		$ 500
Interest rate	5.125%		5.125%	5.125%
2030 Notes
Debt Instrument [Line Items]
Notes payable	$ 550		$ 0
Interest rate	5.00%	5.00%	0.00%
Senior Revolving Credit Facility
Debt Instrument [Line Items]
Senior Revolving Credit Facility	$ 0		$ 20

PENSION PLANS (Details)

PENSION PLANS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Defined Benefit Plan Disclosure [Line Items]
After-tax (benefit) charge to shareholders' equity	$ 76.5	$ 21.3
Pretax (benefit) charge to shareholders' equity	$ 100.6	$ 26.9	$ 66.1
Basis point increase (decrease) in the plans' discount rate reflected in (benefit) charge to shareholders' equity	60	(50)
Actuarial (gain) loss	$ (161.7)	$ 171.3
Benefit obligation	2,667.8	2,883.3	2,717.2
Projected benefit payments [Abstract]
Par outstanding value of bonds used to determine the discount rate yield curve	$ 250
Historic rate of return on plan assets in the last 5 year period (in hundredths)	6.30%
Historic rate of return on plan assets in the last 10 year period (in hundredths)	9.20%
Historic rate of return on plan assets in the last 15 year period (in hundredths)	8.80%
Qualified plans
Projected benefit payments [Abstract]
2,019	$ 140.5
2,020	140.3
2,021	139.4
2,022	138
2,023	135.2
Non-qualified plans
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	5.9	5.8
Projected benefit payments [Abstract]
2,019	0.5
2,020	0.9
2,021	0.5
2,022	0.4
2,023	0.3
Foreign
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer	2.6	1.7	1.3
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	5
U.S.
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer			6
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 0
Accounting Standards Update 2017-07 | Cost of Goods Sold
Projected benefit payments [Abstract]
New Accounting Pronouncement, Quantification of Effect of Adoption		15.3	20.8
Accounting Standards Update 2017-07 | Selling and Administration Expenses
Projected benefit payments [Abstract]
New Accounting Pronouncement, Quantification of Effect of Adoption		$ 19.1	$ 24

PENSION PLANS (Details 1)

PENSION PLANS (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	$ 2,883.3	$ 2,717.2
Service cost	11.1	9.4
Interest cost	86.3	86.6	$ 87.7
Actuarial (gain) loss	(161.7)	171.3
Benefits paid	136.9	134.7
Plan participant’s contributions	1.2	1
Plan amendments	0.4	(1.7)
Foreign currency translation adjustments	(15.1)	30.8
Benefit obligation at end of year	2,667.8	2,883.3	2,717.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plans' assets at beginning of year	2,246.9	2,078.5
Actual return on plans’ assets	(116)	295.6
Employer contributions	2.2	2.6
Benefits paid	135.4	133.5
Foreign currency translation adjustments	(4.7)	3.7
Fair value of plans' assets at end of year	1,993	2,246.9	2,078.5
Qualified plans
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	668.9	630.6
Non-qualified plans
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	5.8
Benefit obligation at end of year	5.9	5.8
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	5.9	5.8
U.S. | Qualified plans
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	436.1	403.7
U.S. | Non-qualified plans
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	3.6	3.7
Foreign | Qualified plans
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	232.8	226.9
Foreign | Non-qualified plans
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	2.3	2.1
Pension Plan
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(674.8)	(636.4)
Pension Plan | U.S.
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	2,579.9	2,466.2
Service cost	1.4	1.2
Interest cost	80.6	81.3
Actuarial (gain) loss	(163.2)	161.7
Benefits paid	133.2	130.5
Plan participant’s contributions	0	0
Plan amendments	0	0
Foreign currency translation adjustments	0	0
Benefit obligation at end of year	2,365.5	2,579.9	2,466.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plans' assets at beginning of year	2,172.5	2,012
Actual return on plans’ assets	(113.9)	290.6
Employer contributions	0.4	0.4
Benefits paid	133.2	130.5
Foreign currency translation adjustments	0	0
Fair value of plans' assets at end of year	1,925.8	2,172.5	2,012
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(439.7)	(407.4)
Pension Plan | Foreign
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	303.4	251
Service cost	9.7	8.2
Interest cost	5.7	5.3
Actuarial (gain) loss	1.5	9.6
Benefits paid	3.7	4.2
Plan participant’s contributions	1.2	1
Plan amendments	0.4	(1.7)
Foreign currency translation adjustments	(15.1)	30.8
Benefit obligation at end of year	302.3	303.4	251
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plans' assets at beginning of year	74.4	66.5
Actual return on plans’ assets	(2.1)	5
Employer contributions	1.8	2.2
Benefits paid	2.2	3
Foreign currency translation adjustments	(4.7)	3.7
Fair value of plans' assets at end of year	67.2	74.4	$ 66.5
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ (235.1)	$ (229)

PENSION PLANS (Details 2)

PENSION PLANS (Details 2) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amounts Recognized in Balance Sheet [Abstract]
Accrued benefit in current liabilities	$ 0.5	$ 0.5
Accrued benefit in noncurrent liabilities	674.3	635.9
Accumulated other comprehensive loss	852.5	786.5
Net balance sheet impact	177.7	150.1
Pension Plan | U.S.
Amounts Recognized in Balance Sheet [Abstract]
Accrued benefit in current liabilities	0.4	0.4
Accrued benefit in noncurrent liabilities	439.3	407
Accumulated other comprehensive loss	796.5	735.1
Net balance sheet impact	356.8	327.7
Pension Plan | Foreign
Amounts Recognized in Balance Sheet [Abstract]
Accrued benefit in current liabilities	0.1	0.1
Accrued benefit in noncurrent liabilities	235	228.9
Accumulated other comprehensive loss	56	51.4
Net balance sheet impact	$ (179.1)	$ (177.6)

PENSION PLANS (Details 3)

PENSION PLANS (Details 3) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Projected benefit obligation	$ 2,667.8	$ 2,883.3
Accumulated benefit obligation	2,641.3	2,851
Fair value of plan assets	$ 1,993	$ 2,246.9

PENSION PLANS (Details 4)

PENSION PLANS (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Net Periodic Benefit (Income) Cost [Abstract]
Service cost	$ 11.1	$ 9.4	$ 9
Interest cost	86.3	86.6	87.7
Expected return on plans’ assets	(146.5)	(149.4)	(154.5)
Amortization of prior service cost	0.1	2.2	0
Recognized actuarial loss	34.5	24.8	20.7
Net periodic benefit (income) costs	(14.5)	(26.4)	(37.1)
Included in Other Comprehensive Loss (Pretax)
Liability adjustment	100.6	26.9	66.1
Amortization of prior service costs and actuarial losses	$ (34.6)	$ (27)	$ (20.7)

PENSION PLANS (Details 5)

PENSION PLANS (Details 5)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted Average Assumptions [Abstract]
Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate for Interest Cost	3.20%
Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Discount Rate for Service Cost	3.70%
Pension Plan | U.S.
Weighted Average Assumptions [Abstract]
Discount rate—periodic benefit cost	3.60%	4.10%	4.40%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	7.75%	7.75%	7.75%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	3.00%	3.00%	3.00%
Discount rate—benefit obligation	4.20%	3.60%	4.10%
Pension Plan | Foreign
Weighted Average Assumptions [Abstract]
Discount rate—periodic benefit cost	2.20%	2.30%	2.70%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.20%	5.60%	6.00%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	2.90%	3.00%	3.00%
Discount rate—benefit obligation	2.20%	2.20%	2.30%

PENSION PLANS (Details 6)

PENSION PLANS (Details 6)	12 Months Ended
	Dec. 31, 2018
Long-term rate of return assumption by asset class [Abstract]
U.S. equities, minimum (in hundredths)	9.00%
U.S. equities, maximum (in hundredths)	13.00%
Non-U.S. equities, minimum (in hundredths)	6.00%
Non-U.S. equities, maximum (in hundredths)	11.00%
Fixed income/cash, minimum (in hundredths)	5.00%
Fixed income/cash, maximum (in hundredths)	9.00%
Alternative investments, minimum (in hundredths)	5.00%
Alternative investments, maximum (in hundredths)	15.00%
Absolute return strategies, minimum (in hundredths)	8.00%
Absolute return strategies, maximum (in hundredths)	12.00%

PENSION PLANS (Details 7)

PENSION PLANS (Details 7)	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	100.00%	100.00%
U.S. equities(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	12.00%	19.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	20.00%
Non-U.S. equities(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	15.00%	17.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	16.00%
Fixed income/cash(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	32.00%	24.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	43.00%
Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	24.00%	21.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	4.00%
Absolute return strategies
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actual Plan Asset Allocations	17.00%	19.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	17.00%
Minimum | U.S. equities(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15.00%
Minimum | Non-U.S. equities(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.00%
Minimum | Fixed income/cash(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	21.00%
Minimum | Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%
Minimum | Absolute return strategies
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%
Maximum | U.S. equities(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	31.00%
Maximum | Non-U.S. equities(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	32.00%
Maximum | Fixed income/cash(1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	75.00%
Maximum | Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	29.00%
Maximum | Absolute return strategies
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	30.00%

PENSION PLANS (Details 8)

PENSION PLANS (Details 8) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	$ 1,423.5
Defined Benefit Plan, Fair Value of Plan Assets	1,993	$ 2,246.9	$ 2,078.5
Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	236.8	301.2
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	332.7	324.9
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
U.S. equities
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	111.5	230.7
Defined Benefit Plan, Fair Value of Plan Assets	248.1	434.4
U.S. equities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	136.6	203.7
U.S. equities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
U.S. equities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Non-U.S. equities
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	255.8	321.9
Defined Benefit Plan, Fair Value of Plan Assets	301.2	392.1
Non-U.S. equities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	44.5	55.6
Non-U.S. equities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0.9	14.6
Non-U.S. equities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	0	0
Defined Benefit Plan, Fair Value of Plan Assets	55.7	41.9
Cash | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	55.7	41.9
Cash | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Government treasuries
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	0.7	0.7
Defined Benefit Plan, Fair Value of Plan Assets	175.7	151.9
Government treasuries | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Government treasuries | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	175	151.2
Government treasuries | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Corporate debt instruments
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	83.7	80.9
Defined Benefit Plan, Fair Value of Plan Assets	222.9	196
Corporate debt instruments | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Corporate debt instruments | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	139.2	115.1
Corporate debt instruments | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	153.6	104.3
Defined Benefit Plan, Fair Value of Plan Assets	171.2	148.3
Asset-backed securities | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Asset-backed securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	17.6	44
Asset-backed securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Hedge fund of funds
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	440.8	430.7
Defined Benefit Plan, Fair Value of Plan Assets	440.8	430.7
Hedge fund of funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Hedge fund of funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Hedge fund of funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Real estate funds
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	22.3	21.8
Defined Benefit Plan, Fair Value of Plan Assets	22.3	21.8
Real estate funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Real estate funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Real estate funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Private equity funds
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	7.6	11.5
Defined Benefit Plan, Fair Value of Plan Assets	7.6	11.5
Private equity funds | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Private equity funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Private equity funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Absolute return strategies
Defined Benefit Plan Disclosure [Line Items]
Investments Net Asset Value	347.5	418.3
Defined Benefit Plan, Fair Value of Plan Assets	347.5	418.3
Absolute return strategies | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Absolute return strategies | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Absolute return strategies | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	$ 0

POSTRETIREMENT BENEFITS (Detail

POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shareholders' Equity Charges
After-tax (benefit) charge to shareholders' equity for other postretirement plans	$ (1.6)	$ (0.3)
Pretax (benefit) charge to shareholders' equity	100.6	26.9	$ 66.1
Other Postretirement Benefit Plans, Defined Benefit
Shareholders' Equity Charges
Pretax (benefit) charge to shareholders' equity	(2.1)	$ 0.4	$ (5.1)
Par outstanding value of non-callable zero coupon bond used to determine the hypothetical yield curve	250
Defined Benefit Plan, Expected Future Benefit Payments in Year One	4
Defined Benefit Plan, Expected Future Benefit Payments in Year Two	4
Defined Benefit Plan, Expected Future Benefit Payments in Year Three	4
Defined Benefit Plan, Expected Future Benefit Payments in Year Four	4
Defined Benefit Plan, Expected Future Benefit Payments in Year Five	$ 4

POSTRETIREMENT BENEFITS (Deta_2

POSTRETIREMENT BENEFITS (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	$ 2,883.3	$ 2,717.2
Service cost	11.1	9.4
Interest cost	86.3	86.6	$ 87.7
Actuarial (gain) loss	(161.7)	171.3
Benefits paid	(136.9)	(134.7)
Foreign currency translation adjustments	(15.1)	30.8
Benefit obligation at end of year	2,667.8	2,883.3	2,717.2
Other Postretirement Benefit Plans, Defined Benefit
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	50.8	52.2
Service cost	1.3	1.1	1.2
Interest cost	1.5	1.5	1.6
Actuarial (gain) loss	(2.1)	0.4
Benefits paid	(3.6)	(4.7)
Foreign currency translation adjustments	(0.9)	0.3
Benefit obligation at end of year	47	50.8	52.2
Funded status	(47)	(50.8)
U.S. | Other Postretirement Benefit Plans, Defined Benefit
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	40.6	43.6
Service cost	0.9	0.8
Interest cost	1.2	1.2
Actuarial (gain) loss	(2)	(0.6)
Benefits paid	(3.2)	(4.4)
Foreign currency translation adjustments	0	0
Benefit obligation at end of year	37.5	40.6	43.6
Funded status	(37.5)	(40.6)
Foreign | Other Postretirement Benefit Plans, Defined Benefit
Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	10.2	8.6
Service cost	0.4	0.3
Interest cost	0.3	0.3
Actuarial (gain) loss	(0.1)	1
Benefits paid	(0.4)	(0.3)
Foreign currency translation adjustments	(0.9)	0.3
Benefit obligation at end of year	9.5	10.2	$ 8.6
Funded status	$ (9.5)	$ (10.2)

POSTRETIREMENT BENEFITS (Deta_3

POSTRETIREMENT BENEFITS (Details 2) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amounts recognized in consolidated balance sheet [Abstract]
Accrued benefit in current liabilities	$ (0.5)	$ (0.5)
Accrued benefit in noncurrent liabilities	(674.3)	(635.9)
Accumulated other comprehensive loss	852.5	786.5
Net balance sheet impact	177.7	150.1
Other Postretirement Benefit Plans, Defined Benefit
Amounts recognized in consolidated balance sheet [Abstract]
Accrued benefit in current liabilities	(3.9)	(4.3)
Accrued benefit in noncurrent liabilities	(43.1)	(46.5)
Accumulated other comprehensive loss	21.1	25.6
Net balance sheet impact	(25.9)	(25.2)
U.S. | Other Postretirement Benefit Plans, Defined Benefit
Amounts recognized in consolidated balance sheet [Abstract]
Accrued benefit in current liabilities	(3.6)	(4)
Accrued benefit in noncurrent liabilities	(33.9)	(36.6)
Accumulated other comprehensive loss	20.1	24.7
Net balance sheet impact	(17.4)	(15.9)
Foreign | Other Postretirement Benefit Plans, Defined Benefit
Amounts recognized in consolidated balance sheet [Abstract]
Accrued benefit in current liabilities	(0.3)	(0.3)
Accrued benefit in noncurrent liabilities	(9.2)	(9.9)
Accumulated other comprehensive loss	1	0.9
Net balance sheet impact	$ (8.5)	$ (9.3)

POSTRETIREMENT BENEFITS (Deta_4

POSTRETIREMENT BENEFITS (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 11.1	$ 9.4
Interest cost	86.3	86.6	$ 87.7
Amortization of prior service cost	0.1	2.2	0
Net periodic benefit cost	14.5	26.4	37.1
Included in Other Comprehensive Loss (Pretax)
Liability adjustment	100.6	26.9	66.1
Amortization of prior service costs and actuarial losses	(37)	(26.9)	(20.4)
Other Postretirement Benefit Plans, Defined Benefit
Components of Net Periodic Benefit Cost [Abstract]
Service cost	1.3	1.1	1.2
Interest cost	1.5	1.5	1.6
Amortization of prior service cost	0	(2.2)	(2.6)
Recognized actuarial loss	2.4	2.1	2.3
Net periodic benefit cost	(5.2)	(2.5)	(2.5)
Included in Other Comprehensive Loss (Pretax)
Liability adjustment	(2.1)	0.4	(5.1)
Amortization of prior service costs and actuarial losses	$ (2.4)	$ 0.1	$ 0.3

POSTRETIREMENT BENEFITS (Deta_5

POSTRETIREMENT BENEFITS (Details 4) - Other Postretirement Benefit Plans, Defined Benefit	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted Average Assumptions [Abstract]
Discount rate—periodic benefit cost	3.50%	3.80%	4.10%
Discount rate—benefit obligation	4.10%	3.50%	3.80%

POSTRETIREMENT BENEFITS (Deta_6

POSTRETIREMENT BENEFITS (Details 5) - Other Postretirement Benefit Plans, Defined Benefit	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Assumed healthcare cost trend rates [Abstract]
Healthcare cost trend rate assumed for next year	7.50%	8.00%
Rate that the cost trend rate gradually declines to	4.50%	4.50%
Year that the rate reaches the ultimate rate	2,024	2,024

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective Tax Rate Reconciliation, Net Benefit from Discrete Items	$ 2.9	$ 452.3	$ 3.9
U.S Tax Cuts and Jobs Act Net Benefit Increase	$ 3.8
Effective Tax Rate Adjusted for Discrete Items	25.70%	17.10%	77.20%
Statutory federal tax rate	21.00%	35.00%	35.00%
2017 Tax Act, Change in Enacted Tax Rate, Amount		$ 315.8
2017 Tax Act, Unremitted Foreign Earnings Amount in Excess of One-time Transition Tax		122.1
2017 Tax Act, Unremitted Foreign Earnings Benefit, Amount		162.6
2017 Tax Act, One-time Transition Tax, Amount		40.5
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	$ 50.2	53.3
Deferred state tax benefits relating to net operating losses	12.2
State tax credit carryforward	18.1
Capital loss carry-forward	8.3
Deferred Tax Assets, Capital Loss Carryforwards	2
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	5
Valuation allowance	147.4	121.4	$ 29
Increases in Valuation Allowances in Foreign Jurisdictions	26
Unrecognized tax benefits [Abstract]
Unrecognized Tax Benefits	33.8	36.3	38.4
Impact on the effective tax rate, if recognized	33	35.5
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount		9.5
Interest and penalties accrued	1.6	1.2
Interest and penalties expense (benefit)	0.4	$ (1.8)	$ (0.4)
Reasonable possibility that unrecognized tax benefits will decrease over next twelve months	7.2
United States
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forward (NOL)	0.5
Deferred Tax Assets, Operating Loss Carryforwards	0.1
Foreign
Operating Loss Carryforwards [Line Items]
Net operating loss carry-forward (NOL)	225.8
Deferred Tax Assets, Operating Loss Carryforwards	38
Operating Loss Carryforwards Subject to Expiration	44.8
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	11
Operating Loss Carryforwards Not Subject to Expiration	181
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	$ 27

INCOME TAXES (Details 1)

INCOME TAXES (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Income (Loss) Before Taxes
Domestic	$ 288	$ 53.3	$ (23.3)
Foreign	149.3	63.9	(10.9)
Income (loss) before taxes	437.3	117.2	(34.2)
Current expense (benefit):
Federal	21.7	(4)	(11.6)
State	5.1	3	0.9
Foreign	48	24.1	15.7
Total current income tax expense	74.8	23.1	5
Deferred expense (benefit):
Federal	27	(549.6)	(10.1)
State	(0.8)	14.6	(5.1)
Foreign	8.4	79.6	(20.1)
Total deferred income tax expense (benefit)	34.6	(455.4)	(35.3)
Income tax provision (benefit)	$ 109.4	$ (432.3)	$ (30.3)

INCOME TAXES (Details 2)

INCOME TAXES (Details 2)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Tax Rate Reconciliation (Percent)
Statutory federal tax rate	21.00%	35.00%	35.00%
State income taxes, net	2.00%	(1.20%)	8.00%
Foreign rate differential	1.80%	(7.70%)	(25.10%)
U.S. tax on foreign earnings	1.10%	(70.80%)	24.40%
Salt depletion	(2.40%)	(16.10%)	45.40%
Change in valuation allowance	3.80%	76.00%	(0.70%)
Remeasurement of U.S. state deferred taxes	(0.60%)	10.20%	9.40%
Change in tax contingencies	(0.70%)	(7.70%)	(9.70%)
U.S. Tax Cuts and Jobs Act	(0.80%)	(373.50%)	0.00%
Share-based payments	0.00%	(5.70%)	0.00%
Dividends paid to Contributing Employee Ownership Plan	(0.10%)	(0.60%)	2.80%
Return to provision	(0.10%)	(0.60%)	5.30%
U.S. Federal tax credits	(0.40%)	(4.20%)	0.60%
Other, net	0.40%	(2.00%)	(6.80%)
Effective tax rate	25.00%	(368.90%)	88.60%

INCOME TAXES (Details 3)

INCOME TAXES (Details 3) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Pension and postretirement benefits	$ 156.8	$ 147.3
Environmental reserves	31.9	33.2
Asset retirement obligations	15.5	14
Accrued liabilities	37	37.6
Tax credits	19.5	37.1
Net operating losses	50.2	53.3
Capital loss carryforward	2	2.1
Other miscellaneous items	23.9	11.2
Total deferred tax assets	336.8	335.8
Valuation allowance	147.4	121.4	$ 29
Net deferred tax assets	189.4	214.4
Deferred tax liabilities:
Property, plant and equipment	541.8	550.3
Intangible amortization	61.6	67.3
Inventory and prepaids	8.3	1
Partnerships	65.2	67.5
Taxes on unremitted earnings	5.1	3.1
Total deferred tax liabilities	682	689.2
Net deferred tax liability	$ (492.6)	$ (474.8)

INCOME TAXES (Details 4)

INCOME TAXES (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Valuation Allowance [Abstract]
Beginning balance	$ 121.4	$ 29
Increases to valuation allowances	31.9	94.5
U.S. Tax Cuts and Jobs Act	0	2.2
Decreases to valuation allowances	(0.9)	(5)
Currency translation adjustment	(5)	0.7
Ending balance	$ 147.4	$ 121.4

INCOME TAXES (Details 5)

INCOME TAXES (Details 5) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Beginning balance	$ 36.3	$ 38.4
Increase for current year tax positions	2.1	2.9
Increase for prior year tax positions	0.3	5.4
Reductions due to statute of limitations	0	(0.1)
Decrease for prior year tax positions	(4.9)	(9.2)
Decrease due to tax settlements	0	(1.1)
Ending balance	$ 33.8	$ 36.3

INCOME TAXES (Details 6)

INCOME TAXES (Details 6)	12 Months Ended
	Dec. 31, 2018
United States | U.S Federal Income Tax | Minimum
Income Tax Examination [Line Items]
Tax years	2,013
United States | U.S Federal Income Tax | Maximum
Income Tax Examination [Line Items]
Tax years	2,017
United States | U.S State Income Tax | Minimum
Income Tax Examination [Line Items]
Tax years	2,006
United States | U.S State Income Tax | Maximum
Income Tax Examination [Line Items]
Tax years	2,017
Canada | Foreign Income Tax | Minimum
Income Tax Examination [Line Items]
Tax years	2,012
Canada | Foreign Income Tax | Maximum
Income Tax Examination [Line Items]
Tax years	2,017
Brazil | Foreign Income Tax | Minimum
Income Tax Examination [Line Items]
Tax years	2,014
Brazil | Foreign Income Tax | Maximum
Income Tax Examination [Line Items]
Tax years	2,017
Germany | Foreign Income Tax | Minimum
Income Tax Examination [Line Items]
Tax years	2,015
Germany | Foreign Income Tax | Maximum
Income Tax Examination [Line Items]
Tax years	2,017
China | Foreign Income Tax | Minimum
Income Tax Examination [Line Items]
Tax years	2,014
China | Foreign Income Tax | Maximum
Income Tax Examination [Line Items]
Tax years	2,017
The Netherlands | Foreign Income Tax | Minimum
Income Tax Examination [Line Items]
Tax years	2,014
The Netherlands | Foreign Income Tax | Maximum
Income Tax Examination [Line Items]
Tax years	2,017

ACCRUED LIABILITIES (Details)

ACCRUED LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities, Current [Abstract]
Accrued compensation and payroll taxes	$ 100	$ 80.6
Tax-related accruals	23.1	21.7
Accrued interest	48.9	37.4
Legal and professional costs	54.4	34.8
Accrued employee benefits	25.3	21.7
Environmental (current portion only)	17	20
Asset retirement obligation (current portion only)	10.6	10.5
Restructuring reserves (current portion only)	7.3	3.3
Other	46.7	44.4
Accrued liabilities	$ 333.3	$ 274.4

CONTRIBUTING EMPLOYEE OWNERSH_2

CONTRIBUTING EMPLOYEE OWNERSHIP PLAN (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan Expense	$ 28.6	$ 29	$ 28.2
Defined Contribution Plan Matching Expense	$ 14.9	$ 11.5	$ 11.2
Initial vesting period (in years)	2
Initial vesting period vested percentage	25.00%
Additional vesting percentage for each additional year of service	25.00%
Years of service for full vesting	5
Vesting percentage after five years	100.00%
Number of days an employee is prohibited from trading out of the fund to which the transfer was made	7
Minimum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation	5.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation	7.50%

STOCK-BASED COMPENSATION (Detai

STOCK-BASED COMPENSATION (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option and long-term incentive plans, exercisable period (in years)	10 years
Stock options, restricted stock and performance shares vesting period (in years)	3 years
Average exercise period for outstanding options (in months)	79 months
Average exercise period for exercisable options (in months)	66 months
Aggregate intrinsic value for outstanding options	$ 9.5
Aggregate intrinsic value for exercisable options	6.4
Total intrinsic value of options exercised	2.9	$ 26.5	$ 2.1
Total unrecognized compensation, unvested	$ 9.8
Total unrecognized compensation, unvested, weighted average recognition period (in years)	16 months
Performance share award cycle (in years)	3
Liability recorded for performance shares to be settled in cash	$ 11.2
Stock Purchase Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Committed shares reserved under the stock purchase plans for non employee Directors | shares	161,049
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation, unvested	$ 5.4
Total unrecognized compensation, unvested, weighted average recognition period (in years)	15 months

STOCK-BASED COMPENSATION (Det_2

STOCK-BASED COMPENSATION (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation	$ 19.3	$ 18.7	$ 11.2
Mark-to-market adjustments	(10.1)	4.5	3
Total expense	$ 9.2	$ 23.2	$ 14.2

STOCK-BASED COMPENSATION STOCK-

STOCK-BASED COMPENSATION STOCK-BASED COMPENSATION (Details 2) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock Options Activity [Rollforward]
Outstanding at beginning of year (in shares)	5,342,526
Granted (in shares)	927,000	1,621,000	1,670,400
Exercised (in shares)	(204,064)
Canceled (in shares)	(201,246)
Outstanding at end of year (in shares)	5,864,216	5,342,526
Option Price, outstanding, beginning of period, minimum (in dollars per share)		$ 13.14
Option price, outstanding, beginning of period, maximum (in dollars per share)	$ 31.90
Option price, granted, minimum (in dollars per share)	32.94
Option price, granted, maximum (in dollars per share)	32.94
Option price, exercised, minimum (in dollars per share)	13.14
Option price exercised, maximum (in dollars per share)	29.75
Option price, canceled, minimum (in dollars per share)	13.14
Option price, canceled, maximum (in dollars per share)	32.94
Option price, outstanding, minimum, end of period (in dollars per share)	13.14
Option price, outstanding, maximum, end of period (in dollars per share)	32.94
Weighted average option price, beginning of period (in dollars per share)	22.72
Weighted-average exercise price (in dollars)	32.94	29.82	$ 13.14
Weighted average option price, exercised (in dollars per share)	17.68
Weighted average option price, canceled (in dollars per share)	25.92
Weighted average option price, outstanding, end of period (in dollars per share)	$ 24.40	$ 22.72
Options exercisable, beginning of period (in shares)	2,603,962
Options exercisable, end of period (in shares)	3,571,732	2,603,962
Weighted average exercise price, exercisable, beginning of period (in dollars per share)	$ 21.78
Weighted average exercise price, exercisable, end of period (in dollars per share)	$ 22.27	$ 21.78

STOCK-BASED COMPENSATION (Det_3

STOCK-BASED COMPENSATION (Details 3)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercisable (in shares) | shares	3,571,732
Options outstanding (in shares) | shares	5,864,216
$20.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise price, minimum, (in dollars per share)	$ 0
Range of exercise price, maximum, (in dollars per share)	$ 20
Options exercisable (in shares) | shares	1,129,630
Weighted average exercise price, exercisable (in dollars per share)	$ 14.19
Options outstanding (in shares) | shares	1,579,848
Weighted average exercise price, outstanding (in dollars per share)	$ 13.89
$20.00 - $26.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise price, minimum, (in dollars per share)	20
Range of exercise price, maximum, (in dollars per share)	$ 26
Options exercisable (in shares) | shares	1,290,236
Weighted average exercise price, exercisable (in dollars per share)	$ 23.77
Options outstanding (in shares) | shares	1,290,236
Weighted average exercise price, outstanding (in dollars per share)	$ 23.77
$26.00
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise price, minimum, (in dollars per share)	$ 26
Options exercisable (in shares) | shares	1,151,866
Weighted average exercise price, exercisable (in dollars per share)	$ 28.49
Options outstanding (in shares) | shares	2,994,132
Weighted average exercise price, outstanding (in dollars per share)	$ 30.22

STOCK-BASED COMPENSATION (Det_4

STOCK-BASED COMPENSATION (Details 4)	Dec. 31, 2018shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sub-limit for all types of stock awards included in available to be issued stock options (in shares)	1,989,000
2000 long term incentive plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	44,130
Number of shares available for grant or purchase (in shares)	0
2003 long term incentive plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	215,584
Number of shares available for grant or purchase (in shares)	0
2006 long term incentive plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	278,270
Number of shares available for grant or purchase (in shares)	0
2009 long term incentive plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	1,873,421
Number of shares available for grant or purchase (in shares)	0
2014 long term incentive plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	2,098,802
Number of shares available for grant or purchase (in shares)	0
2016 long term incentive plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	2,326,334
Number of shares available for grant or purchase (in shares)	0
2018 long term incentive plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	9,263,665
Number of shares available for grant or purchase (in shares)	9,252,665
Long Term Incentive Stock Option Plan Reserved for Issuance
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	16,100,206
Long Term Incentive Stock Option Plan Available for Grant or Purchase
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant or purchase (in shares)	9,252,665
1997 stock plan for non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved for Issuance (in shares)	536,295
Number of shares available for grant or purchase (in shares)	375,245

STOCK-BASED COMPENSATION (Det_5

STOCK-BASED COMPENSATION (Details 5)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Unvested Performance Shares [Rollforward]
Unvested, beginning of period (in shares) | shares	202,017
Granted (in shares) | shares	81,626
Vested (in shares) | shares	(163,901)
Canceled (in shares) | shares	(14,125)
Unvested, end of period (in shares) | shares	105,617
Weighted average fair value per share, beginning of period (in dollars per share) | $ / shares	$ 35.62
Weighted average fair value per share, granted (in dollars per share) | $ / shares	32.67
Weighted average fair value per share, vested (in dollars per share) | $ / shares	19.89
Weighted average fair value per share, canceled (in dollars per share) | $ / shares	34.68
Weighted average fair value per share, end of period (in dollars per share) | $ / shares	$ 19.89
To Settle in Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding at beginning of period, performance shares (in shares) | shares	650,689
Granted, performance shares (in shares) | shares	81,626
Paid/Issued, performance shares (in shares) | shares	(77,262)
Performance shares converted to cash | shares	29,375
Canceled, performance shares (in shares) | shares	(14,125)
Shares outstanding at end of period, performance shares (in shares) | shares	670,303
Total vested at end of period, performance shares (in shares) | shares	564,686
Weighted average fair value, outstanding at beginning of period, performance shares (in dollars per share) | $ / shares	$ 35.62
Weighted average fair value, granted, performance shares (in dollars per share) | $ / shares	32.67
Weighted average fair value, paid/issued, performance shares (in dollars per share) | $ / shares	35.62
Weighted average fair value, converted from shares to cash, performance shares (in dollars per shares) | $ / shares	17.88
Weighted average fair value, canceled, performance shares (in dollars per share) | $ / shares	34.68
Weighted average fair value, outstanding at end of period, performance shares (in dollars per share) | $ / shares	19.89
Weighted average fair value, total vested at end of period, performance shares (in dollars per share) | $ / shares	$ 19.89
To Settle in Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding at beginning of period, performance shares (in shares) | shares	480,200
Granted, performance shares (in shares) | shares	88,500
Paid/Issued, performance shares (in shares) | shares	(34,500)
Performance shares converted to cash | shares	(29,375)
Canceled, performance shares (in shares) | shares	(14,125)
Shares outstanding at end of period, performance shares (in shares) | shares	490,700
Total vested at end of period, performance shares (in shares) | shares	385,083
Weighted average fair value, outstanding at beginning of period, performance shares (in dollars per share) | $ / shares	$ 19.81
Weighted average fair value, granted, performance shares (in dollars per share) | $ / shares	33.03
Weighted average fair value, paid/issued, performance shares (in dollars per share) | $ / shares	27.40
Weighted average fair value, converted from shares to cash, performance shares (in dollars per shares) | $ / shares	17.88
Weighted average fair value, canceled, performance shares (in dollars per share) | $ / shares	26.51
Weighted average fair value, outstanding at end of period, performance shares (in dollars per share) | $ / shares	21.58
Weighted average fair value, total vested at end of period, performance shares (in dollars per share) | $ / shares	$ 18.95

SHAREHOLDERS' EQUITY (Details)

SHAREHOLDERS' EQUITY (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 26, 2018
Equity, Class of Treasury Stock [Line Items]
Cost of common stock repurchased and retired	$ 50	$ 0	$ 0
Stock options exercised (in shares)	0.2	1.7	0.3
Total value of stock options exercised	$ 3.4	$ 32.4	$ 4.1
Foreign currency translation adjustment [Roll Forward]
Beginning balance	7.6	(24.1)	(12.1)
Unrealized (losses) gains	(22.2)	55.6	(22.4)
Reclassification adjustments of (gains) losses into income	0	0	0
Tax benefit (provision)	0	(23.9)	10.4
Net change	(22.2)	31.7	(12)
Ending balance	0.7	7.6	(24.1)
Unrealized gains (losses) on derivative contracts (net of taxes) [Roll Forward]
Beginning balance	11.1	12.8	(6.9)
Unrealized (losses) gains	(1.1)	1.9	26.3
Reclassification adjustments of (gains) losses into income	(14.3)	(4.6)	5.8
Tax benefit (provision)	3.7	1	(12.4)
Net change	(11.7)	(1.7)	19.7
Ending balance	1.8	11.1	12.8
Pension and postretirement benefits (net of taxes) [Roll Forward]
Beginning balance	(503.3)	(498.7)	(473.5)
Unrealized (losses) gains	(98.5)	(27.3)	(61)
Reclassification adjustments of (gains) losses into income	37	26.9	20.4
Tax benefit (provision)	(14.9)	4.2	(15.4)
Net change	(46.6)	(4.6)	(25.2)
Ending balance	(653.5)	(503.3)	(498.7)
Accumulated other comprehensive loss [Roll Forward]
Beginning balance	(484.6)	(510)	(492.5)
Unrealized (losses) gains	(121.8)	30.2	(57.1)
Reclassification adjustments of (gains) losses into income	22.7	22.3	26.2
Tax benefit (provision)	18.6	(27.1)	13.4
Net change	(80.5)	25.4	(17.5)
Ending balance	(651)	$ (484.6)	(510)
Income Tax Reclassification Adjustment, Foreign Currency Translation	15.3
Income Tax Reclassification Adjustment, Derivative Contracts	2.4
Income Tax Reclassification Adjustment, Pension and Postretirement Benefits	$ (103.6)
Common Stock | 2018 Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Authorized share repurchase program (in dollars)				$ 500
Total repurchased shares under this program (in shares)	2.1
Cost of common stock repurchased and retired			$ 50
Remaining authorized repurchase amount (in dollars)	$ 450
Accounting Standards Update 2018-02
Accumulated other comprehensive loss [Roll Forward]
Income Tax Accounting Standard Adoption	$ (85.9)

SEGMENT INFORMATION (Details 1)

SEGMENT INFORMATION (Details 1) - USD ($) $ in Millions	3 Months Ended								12 Months Ended			98 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Sales [Abstract]
Sales	$ 1,635	$ 1,872.4	$ 1,728.4	$ 1,710.3	$ 1,619.9	$ 1,554.9	$ 1,526.5	$ 1,567.1	$ 6,946.1	$ 6,268.4	$ 5,550.6
Income (loss) before taxes [Abstract]
Income (loss) before taxes									(437.3)	(117.2)	34.2
Environmental income (expense)									(103.7)	8.5	9.2
Restructuring charge									(21.9)	(37.6)	(112.9)	$ (209.1)
Acquisition-related costs									(1)	(12.8)	(48.8)
Other operating income									6.4	3.3	10.6
Interest expense									(243.2)	(217.4)	(191.9)
Interest income									1.6	1.8	3.4
Non-operating pension income									21.7	34.4	44.8
Earnings (losses) of non-consolidated affiliates [Abstract]
Earnings (losses) of non-consolidated affiliates									(19.7)	1.8	1.7
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									601.4	558.9	533.5
Capital spending [Abstract]
Total capital spending									385.2	294.3	278
Assets
Total assets	8,997.4				9,218.3				8,997.4	9,218.3		8,997.4
Investments-Affiliated Companies (at equity) [Abstract]
Investments in non-consolidated affiliates	8.8				28.5				8.8	28.5		8.8
Chlor Alkali Products and Vinyls
Sales [Abstract]
Sales									3,986.7	3,500.8	2,999.3
Income (loss) before taxes [Abstract]
Income (loss) before taxes									(637.1)	(405.8)	(224.9)
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									473.1	432.2	418.1
Capital spending [Abstract]
Total capital spending									259.9	209.5	195.1
Assets
Total assets	6,837.2				7,008				6,837.2	7,008		6,837.2
Investments-Affiliated Companies (at equity) [Abstract]
Investments in non-consolidated affiliates	8.8				28.5				8.8	28.5		8.8
Epoxy
Sales [Abstract]
Sales									2,303.1	2,086.4	1,822
Income (loss) before taxes [Abstract]
Income (loss) before taxes									(52.8)	11.8	(15.4)
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									102.4	94.3	90
Capital spending [Abstract]
Total capital spending									36.3	37.9	45.4
Assets
Total assets	1,521.9				1,597.1				1,521.9	1,597.1		1,521.9
Winchester
Sales [Abstract]
Sales									656.3	681.2	729.3
Income (loss) before taxes [Abstract]
Income (loss) before taxes									(38.4)	(72.4)	(120.9)
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									20	19.5	18.5
Capital spending [Abstract]
Total capital spending									14.7	22.5	19.5
Assets
Total assets	399.9				425.2				399.9	425.2		399.9
Corporate/Other
Income (loss) before taxes [Abstract]
Environmental income (expense)									103.7	(8.5)	(9.2)
Other corporate and unallocated costs									(158.3)	(112.4)	(91.4)
Restructuring charge									(21.9)	(37.6)	(112.9)
Acquisition-related costs									(1)	(12.8)	(48.8)
Depreciation and amortization expense [Abstract]
Total depreciation and amortization expense									5.9	12.9	6.9
Capital spending [Abstract]
Total capital spending									74.3	24.4	$ 18
Assets
Total assets	$ 238.4				$ 188				$ 238.4	$ 188		$ 238.4

SEGMENT INFORMATION (Details 2)

SEGMENT INFORMATION (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Sales	$ 6,946.1	$ 6,268.4	$ 5,550.6
United States
Disaggregation of Revenue [Line Items]
Sales	3,944.4	3,556.1	3,355.2
Europe
Disaggregation of Revenue [Line Items]
Sales	1,183.9	1,082.5	923.9
Other foreign
Disaggregation of Revenue [Line Items]
Sales	1,817.8	1,629.8	1,271.5
Chlor Alkali Products and Vinyls
Disaggregation of Revenue [Line Items]
Sales	3,986.7	3,500.8	2,999.3
Chlor Alkali Products and Vinyls | Caustic soda
Disaggregation of Revenue [Line Items]
Sales	2,198.6	1,904.3	1,479.3
Chlor Alkali Products and Vinyls | Chlorine, chlorine derivatives and other co-products
Disaggregation of Revenue [Line Items]
Sales	1,788.1	1,596.5	1,520
Chlor Alkali Products and Vinyls | United States
Disaggregation of Revenue [Line Items]
Sales	2,610.7	2,294.4	2,161.3
Chlor Alkali Products and Vinyls | Europe
Disaggregation of Revenue [Line Items]
Sales	181.8	130.1	121.3
Chlor Alkali Products and Vinyls | Other foreign
Disaggregation of Revenue [Line Items]
Sales	1,194.2	1,076.3	716.7
Epoxy
Disaggregation of Revenue [Line Items]
Sales	2,303.1	2,086.4	1,822
Epoxy | Aromatics and allylics
Disaggregation of Revenue [Line Items]
Sales	1,145.7	1,051.1	844.4
Epoxy | Epoxy resins
Disaggregation of Revenue [Line Items]
Sales	1,157.4	1,035.3	977.6
Epoxy | United States
Disaggregation of Revenue [Line Items]
Sales	742.7	646.5	532.4
Epoxy | Europe
Disaggregation of Revenue [Line Items]
Sales	991.1	940.8	787.6
Epoxy | Other foreign
Disaggregation of Revenue [Line Items]
Sales	569.3	499.1	502
Winchester
Disaggregation of Revenue [Line Items]
Sales	656.3	681.2	729.3
Winchester | Commercial
Disaggregation of Revenue [Line Items]
Sales	427.6	471	559.7
Winchester | Military and law enforcement
Disaggregation of Revenue [Line Items]
Sales	228.7	210.2	169.6
Winchester | United States
Disaggregation of Revenue [Line Items]
Sales	591	615.2	661.5
Winchester | Europe
Disaggregation of Revenue [Line Items]
Sales	11	11.6	15
Winchester | Other foreign
Disaggregation of Revenue [Line Items]
Sales	$ 54.3	$ 54.4	$ 52.8

SEGMENT INFORMATION (Details 3)

SEGMENT INFORMATION (Details 3) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Long-Lived Assets [Line Items]
Long-lived assets	$ 3,482.1	$ 3,575.8
United States
Long-Lived Assets [Line Items]
Long-lived assets	3,147.6	3,211.9
Foreign
Long-Lived Assets [Line Items]
Long-lived assets	$ 334.5	$ 363.9

ENVIRONMENTAL (Details 1)

ENVIRONMENTAL (Details 1) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Accrued liabilities for unasserted claims	$ 8.6
Maximum period for required site OM and M expense accrual (in years)	30
Environmental loss contingencies accrual
Beginning balance	$ 131.6	$ 137.3
Provisions charged to income	7.3	10.3	$ 9.2
Remedial and investigatory spending	(13)	(16.5)
Foreign currency translation adjustments	(0.3)	0.5
Ending balance	125.6	131.6	$ 137.3
Reserves for environmental expenditures-noncurrent	108.6	$ 111.6
Future environmental expenditures expected to be utilized over the next 5 years	68.9
Future environmental expenditures expected to be utilized over the next 6 to 10 years	14.1
Future environmental expenditures expected to be utilized beyond 10 years	$ 42.6
Number of sites included in the total estimated environmental liability	60
Number of United States Environmental Protection Agency National Priority List sites	14
Number of sites which constituted the largest portion of the environmental liability	9
Percentage of environmental liability that the larger sites made up (in hundredths)	79.00%
Number of sites which constituted the smallest portion of the environmental liability	51
Percentage of environmental liability any one of the smallest sites made up, maximum (in hundredths)	3.00%
Number of larger sites in which part of the site is subject to a remedial investigation and another part is in the long-term OM and M stage	3
Number of larger sites in which for part of the site a remedial action plan is being developed and for the other part a remedial design being developed	2
Number of larger sites subject to remedial investigation and remedial design being developed	1
Number of Larger Sites in Remedial Action Plan and Long-Term OM&M.	1
Number of larger sites which are in long-term OM and M	2
Percentage of environmental liability any one of the largest sites made up., maximum (in hundredths)	22.00%
Possible additional contingent environmental liabilities	$ 60
Minimum
Expected annual environmental-related cash outlay for site investigation and remediation	15
Maximum
Expected annual environmental-related cash outlay for site investigation and remediation	$ 25

ENVIRONMENTAL (Details 2)

ENVIRONMENTAL (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Environmental Remediation Obligations [Abstract]
Provisions charged to income	$ 7.3	$ 10.3	$ 9.2
Insurance recoveries for costs incurred and expensed	(111)	(1.8)	0
Environmental (income) expense	(103.7)	$ 8.5	$ 9.2
Gross Recoveries from Third Parties of Costs Incurred and Expensed in Prior Periods	121
Environmental Recoveries Owed to Third-Party	10
Environmental Possible Additional Contingent Environmental Liabilities	$ 60

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Future minimum operating leases [Abstract]
2,019	$ 82.2
2,020	61.4
2,021	44.2
2,022	31.8
2,023	23.2
Thereafter	102.6
Total operating leases	345.4
Future minimum purchase commitments [Abstract]
2,019	678.5
2,020	642.5
2,021	727.7
2,022	725
2,023	725
Thereafter	4,424.9
Total purchase commitments	7,923.6
Total rent expense charged to operations	122.4	$ 118.5	$ 95.5
2017 Supply Contract Payment		209.4
Long-term Purchase Commitment [Line Items]
2020 Supply Contract Payment		389.2
2020 Supply Contract Payment Total Accretion		51.8
2020 Supply Contract Accretion Expense	16	3.9
Legal action liabilities	15.6	24.8
Estimated Insurance Recoveries		8
Gain in Other Operating Income due to Insurance Recoveries	8	$ 0	$ 11
Minimum
Long-term Purchase Commitment [Line Items]
2020 Supply Contract Payment	440
Maximum
Long-term Purchase Commitment [Line Items]
2020 Supply Contract Payment	$ 465

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016	Jun. 30, 2016
Derivative [Line Items]
Derivative, Notional Amount	$ 116.5	$ 92.8
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	(5.3)
Derivative Liability, Fair Value, Gross Liability	37.6	31.9
Interest Rate Contract Gains
Derivative [Line Items]
Cash Flow Hedges Derivative Instruments at Fair Value, Net	(5.3)
Commodity Contract
Derivative [Line Items]
Cash Flow Hedges Derivative Instruments at Fair Value, Net	2.6
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	2.3
Forward Contracts
Derivative [Line Items]
Derivative, Notional Amount	123.7	135.5
Forward Contracts Sell
Derivative [Line Items]
Derivative, Notional Amount	82.6	97.7
Interest Rate Swaps Designated As Fair Value Hedges
Derivative [Line Items]
Derivative, Notional Amount	500	500		$ 250	$ 250
Derivative Liability, Fair Value, Gross Liability	33.7
Derivative, Gain (Loss) on Derivative, Net	(2.1)	2.9	$ 2.6
Fixed Interest Rate Swaps $1,100M (Tranche 1)
Derivative [Line Items]
Derivative, Notional Amount					1,100
Fixed Interest Rate Swaps $900M (Tranche 2)
Derivative [Line Items]
Derivative, Notional Amount					900
Fixed Interest Rate Swaps $400M (Tranche 3)
Derivative [Line Items]
Derivative, Notional Amount					$ 400
Cash Flow Hedging | Interest Expense | Interest Rate Contract Gains
Derivative [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	$ 8.9	$ 3.1	$ 0

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS (Details 1) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative, Notional Amount	$ 116.5	$ 92.8
Natural Gas Commodity Forward Contracts
Derivative [Line Items]
Derivative, Notional Amount	58.4	39.2
Other Commodity Forward Contracts
Derivative [Line Items]
Derivative, Notional Amount	$ 58.1	$ 53.6

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS (Details 2) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 6.4	$ 22.8
Derivative Liability, Fair Value, Gross Liability	37.6	31.9
Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	5.7	19.2
Other Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0.7	3.6
Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	3.5	3.8
Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	34.1	28.1
Designated as Hedging Instrument | Interest Rate Contract Gains | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	5.3	6.9
Designated as Hedging Instrument | Interest Rate Contract Gains | Other Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	3.6
Designated as Hedging Instrument | Interest Rate Contract Loss | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	33.7	28.1
Designated as Hedging Instrument | Commodity Contracts Losses | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	(0.1)
Designated as Hedging Instrument | Commodity Contracts Losses | Other Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	(0.2)	0
Designated as Hedging Instrument | Commodity Contracts Losses | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	4.9	3.8
Designated as Hedging Instrument | Commodity Contracts Losses | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0.5	0
Designated as Hedging Instrument | Commodity Contracts Gains | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	11.4
Designated as Hedging Instrument | Commodity Contracts Gains | Other Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0.9	0
Designated as Hedging Instrument | Commodity Contracts Gains | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(1.9)	0
Designated as Hedging Instrument | Commodity Contracts Gains | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	(0.1)	0
Not Designated as Hedging Instrument | Foreign Exchange Contract Loss | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	(0.5)	(1)
Not Designated as Hedging Instrument | Foreign Exchange Contract Loss | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0.6	0
Not Designated as Hedging Instrument | Foreign Exchange Contract | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0.9	2
Not Designated as Hedging Instrument | Foreign Exchange Contract | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ (0.1)	$ 0

DERIVATIVE FINANCIAL INSTRUME_6

DERIVATIVE FINANCIAL INSTRUMENTS (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ (1.1)	$ 1.9	$ 26.3
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	14.3	4.6	(5.8)
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(5.4)	1.8	(11.5)
Commodity Contract | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(4.8)	(2.1)	16.7
Commodity Contract | Cost of Goods Sold | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	5.4	1.5	(5.8)
Commodity Contract | Cost of Goods Sold | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	(0.4)
Interest Rate Contract Gains | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	3.7	4	9.6
Interest Rate Contract Gains | Interest Expense | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	8.9	3.1	0
Interest Rate Contract Gains | Interest Expense | Fair Value Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2.1)	3	3.7
Foreign Exchange Contract | Selling and Administration Expenses | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (5.4)	$ 1.8	$ (11.1)

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Non-recurring Fair Value, Assets	$ 0	$ 0

FAIR VALUE MEASUREMENTS (Deta_2

FAIR VALUE MEASUREMENTS (Details 1) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Swap Asset Fair Value Disclosure	$ 5.3	$ 10.5
Commodity Forward Contracts Asset Fair Value Disclosure	0.7	11.3
Foreign Currency Contract, Asset, Fair Value Disclosure	0.4	1
Total Asset Fair Value Disclosure	6.4	22.8
Interest Rate Swap Liability Fair Value Disclosure	33.7	28.1
Commodity Forward Contracts Liability Fair Value Disclosure	3.4	3.8
Foreign Currency Contracts, Liability, Fair Value Disclosure	0.5
Total Liability Fair Value Disclosure	37.6	31.9
Quoted Prices In Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Swap Asset Fair Value Disclosure	0	0
Commodity Forward Contracts Asset Fair Value Disclosure	0	0
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Total Asset Fair Value Disclosure	0	0
Interest Rate Swap Liability Fair Value Disclosure	0	0
Commodity Forward Contracts Liability Fair Value Disclosure	0	0
Foreign Currency Contracts, Liability, Fair Value Disclosure	0
Total Liability Fair Value Disclosure	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Swap Asset Fair Value Disclosure	5.3	10.5
Commodity Forward Contracts Asset Fair Value Disclosure	0.7	11.3
Foreign Currency Contract, Asset, Fair Value Disclosure	0.4	1
Total Asset Fair Value Disclosure	6.4	22.8
Interest Rate Swap Liability Fair Value Disclosure	33.7	28.1
Commodity Forward Contracts Liability Fair Value Disclosure	3.4	3.8
Foreign Currency Contracts, Liability, Fair Value Disclosure	0.5
Total Liability Fair Value Disclosure	37.6	31.9
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Swap Asset Fair Value Disclosure	0	0
Commodity Forward Contracts Asset Fair Value Disclosure	0	0
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Total Asset Fair Value Disclosure	0	0
Interest Rate Swap Liability Fair Value Disclosure	0	0
Commodity Forward Contracts Liability Fair Value Disclosure	0	0
Foreign Currency Contracts, Liability, Fair Value Disclosure	0
Total Liability Fair Value Disclosure	$ 0	$ 0

FAIR VALUE MEASUREMENTS (Deta_3

FAIR VALUE MEASUREMENTS (Details 2) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Long-term Debt, Fair Value	$ 3,290.2	$ 3,911
Debt, Long-term and Short-term, Combined Amount	3,230.3	3,612
Quoted Prices In Active Markets for Identical Assets (Level 1)
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Long-term Debt, Fair Value	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Long-term Debt, Fair Value	3,137.2	3,758
Significant Unobservable Inputs (Level 3)
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Long-term Debt, Fair Value	$ 153	$ 153

SUPPLEMENTAL GUARANTOR FINANC_3

SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Oct. 05, 2015
2023 Notes
Business Acquisition [Line Items]
2023 Senior Notes			$ 720
Interest rate	9.75%	9.75%	9.75%
2025 Notes
Business Acquisition [Line Items]
Interest rate	10.00%	10.00%	10.00%
2025 Senior Notes			$ 500

SUPPLEMENTAL GUARANTOR FINANC_4

SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION (Balance Sheet)(Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	$ 178.8	$ 218.4	$ 184.5	$ 392
Receivables, net	776.3	733.2
Intercompany receivables	0	0
Income taxes receivable	5.9	16.9
Inventories, net	711.4	682.6
Other current assets	35	48.1
Total current assets	1,707.4	1,699.2
Property, plant and equipment, net	3,482.1	3,575.8
Investment in subsidiaries	0	0
Deferred income taxes	26.3	36.4
Other assets	1,150.4	1,208.4
Long-term receivables—affiliates	0	0
Intangible assets, net	511.6	578.5
Goodwill	2,119.6	2,120	2,118
Total assets	8,997.4	9,218.3
Current installments of long-term debt	125.9	0.7
Accounts payable	636.5	669.8
Intercompany payables	0	0
Income taxes payable	22.6	9.4
Accrued liabilities	333.3	274.4
Total current liabilities	1,118.3	954.3
Long-term debt	3,104.4	3,611.3
Accrued pension liability	674.3	635.9
Deferred Income Tax Liabilities, Net	518.9	511.2
Long-term payables—affiliates	0	0
Other liabilities	749.3	751.9
Total liabilities	6,165.2	6,464.6
Commitments and contingencies
Common stock	165.3	167.1
Additional paid-in capital	2,247.4	2,280.9
Accumulated other comprehensive loss	(651)	(484.6)	(510)	(492.5)
Retained earnings	1,070.5	790.3
Total shareholders' equity	2,832.2	2,753.7	2,273	2,418.8
Total liabilities and shareholders' equity	8,997.4	9,218.3
Parent Guarantor
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	92	57.1	25.2	119.4
Receivables, net	99.7	95.6
Intercompany receivables	0	0
Income taxes receivable	2.6	11.7
Inventories, net	161.4	155.4
Other current assets	220.2	206.2
Total current assets	575.9	526
Property, plant and equipment, net	651.4	544.4
Investment in subsidiaries	6,943.3	6,680.4
Deferred income taxes	7.3	38.1
Other assets	24.3	45.9
Long-term receivables—affiliates	0	0
Intangible assets, net	0.3	0.3
Goodwill	0	0
Total assets	8,202.5	7,835.1
Current installments of long-term debt	0.9	0.7
Accounts payable	90.1	83.2
Intercompany payables	2,558.2	2,093.2
Income taxes payable	3.9	0
Accrued liabilities	150.3	117.7
Total current liabilities	2,803.4	2,294.8
Long-term debt	1,357.5	839.4
Accrued pension liability	439.1	406.7
Deferred Income Tax Liabilities, Net	0	0
Long-term payables—affiliates	469.6	1,250
Other liabilities	300.7	290.5
Total liabilities	5,370.3	5,081.4
Commitments and contingencies
Common stock	165.3	167.1
Additional paid-in capital	2,247.4	2,280.9
Accumulated other comprehensive loss	(651)	(484.6)
Retained earnings	1,070.5	790.3
Total shareholders' equity	2,832.2	2,753.7
Total liabilities and shareholders' equity	8,202.5	7,835.1
Issuer
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	0	0	0	0
Receivables, net	0	0
Intercompany receivables	0	0
Income taxes receivable	0	0
Inventories, net	0	0
Other current assets	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Investment in subsidiaries	4,286.9	4,092.3
Deferred income taxes	0	0
Other assets	0	0
Long-term receivables—affiliates	1,247.2	2,137.8
Intangible assets, net	0	0
Goodwill	966.3	966.3
Total assets	6,500.4	7,196.4
Current installments of long-term debt	0	0
Accounts payable	0	0
Intercompany payables	0	0
Income taxes payable	0	0
Accrued liabilities	0	0
Total current liabilities	0	0
Long-term debt	1,746.9	2,522.2
Accrued pension liability	0	0
Deferred Income Tax Liabilities, Net	6	3
Long-term payables—affiliates	0	0
Other liabilities	5.5	5.6
Total liabilities	1,758.4	2,530.8
Commitments and contingencies
Common stock	0	0
Additional paid-in capital	4,125.7	4,125.7
Accumulated other comprehensive loss	0	0
Retained earnings	616.3	539.9
Total shareholders' equity	4,742	4,665.6
Total liabilities and shareholders' equity	6,500.4	7,196.4
Subsidiary Non-Guarantor
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	86.8	161.3	159.3	272.6
Receivables, net	676.6	637.6
Intercompany receivables	2,558.2	2,093.2
Income taxes receivable	3.3	6.3
Inventories, net	550	527.2
Other current assets	1.8	5.3
Total current assets	3,876.7	3,430.9
Property, plant and equipment, net	2,830.7	3,031.4
Investment in subsidiaries	0	0
Deferred income taxes	27.4	34.5
Other assets	1,126.1	1,162.5
Long-term receivables—affiliates	0	0
Intangible assets, net	511.3	578.2
Goodwill	1,153.3	1,153.7
Total assets	9,525.5	9,391.2
Current installments of long-term debt	125	0
Accounts payable	549.4	590
Intercompany payables	0	0
Income taxes payable	18.7	10.5
Accrued liabilities	367.5	318.1
Total current liabilities	1,060.6	918.6
Long-term debt	0	249.7
Accrued pension liability	235.2	229.2
Deferred Income Tax Liabilities, Net	521.3	544.4
Long-term payables—affiliates	777.6	887.8
Other liabilities	443.1	455.8
Total liabilities	3,037.8	3,285.5
Commitments and contingencies
Common stock	14.6	14.6
Additional paid-in capital	4,808.2	4,808.2
Accumulated other comprehensive loss	(6.9)	(4.6)
Retained earnings	1,671.8	1,287.5
Total shareholders' equity	6,487.7	6,105.7
Total liabilities and shareholders' equity	9,525.5	9,391.2
Eliminations
Supplemental Guarantor Financial Information Balance Sheets [Line Items]
Cash and cash equivalents	0	0	$ 0	$ 0
Receivables, net	0	0
Intercompany receivables	(2,558.2)	(2,093.2)
Income taxes receivable	0	(1.1)
Inventories, net	0	0
Other current assets	(187)	(163.4)
Total current assets	(2,745.2)	(2,257.7)
Property, plant and equipment, net	0	0
Investment in subsidiaries	(11,230.2)	(10,772.7)
Deferred income taxes	(8.4)	(36.2)
Other assets	0	0
Long-term receivables—affiliates	(1,247.2)	(2,137.8)
Intangible assets, net	0	0
Goodwill	0	0
Total assets	(15,231)	(15,204.4)
Current installments of long-term debt	0	0
Accounts payable	(3)	(3.4)
Intercompany payables	(2,558.2)	(2,093.2)
Income taxes payable	0	(1.1)
Accrued liabilities	(184.5)	(161.4)
Total current liabilities	(2,745.7)	(2,259.1)
Long-term debt	0	0
Accrued pension liability	0	0
Deferred Income Tax Liabilities, Net	(8.4)	(36.2)
Long-term payables—affiliates	(1,247.2)	(2,137.8)
Other liabilities	0	0
Total liabilities	(4,001.3)	(4,433.1)
Commitments and contingencies
Common stock	(14.6)	(14.6)
Additional paid-in capital	(8,933.9)	(8,933.9)
Accumulated other comprehensive loss	6.9	4.6
Retained earnings	(2,288.1)	(1,827.4)
Total shareholders' equity	(11,229.7)	(10,771.3)
Total liabilities and shareholders' equity	$ (15,231)	$ (15,204.4)

SUPPLEMENTAL GUARANTOR FINANC_5

SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION (Statements of Operations)(Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended			98 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018
Supplemental Guarantor Financial Information Statement of Operations [Line Items]
Sales	$ 1,635	$ 1,872.4	$ 1,728.4	$ 1,710.3	$ 1,619.9	$ 1,554.9	$ 1,526.5	$ 1,567.1	$ 6,946.1	$ 6,268.4	$ 5,550.6
Cost of goods sold	1,391	1,441.7	1,460.7	1,528.7	1,400.2	1,349.3	1,407.9	1,397.5	5,822.1	5,554.9	4,944.5
Selling and administration									430.6	369.8	347.2
Restructuring charges									21.9	37.6	112.9	$ 209.1
Acquisition-related costs									1	12.8	48.8
Other operating (loss) income									6.4	3.3	10.6
Operating income (loss)									(676.9)	(296.6)	(107.8)
Earnings (losses) of non-consolidated affiliates									(19.7)	1.8	1.7
Equity income in subsidiaries									0	0	0
Interest expense									243.2	217.4	191.9
Interest income									1.6	1.8	3.4
Non-operating pension income (expense)									21.7	34.4	44.8
Income (loss) before taxes									437.3	117.2	(34.2)
Income tax (benefit) provision									109.4	(432.3)	(30.3)
Net income (loss)	$ 53.3	$ 195.1	$ 58.6	$ 20.9	$ 489.3	$ 52.7	$ (5.9)	$ 13.4	327.9	549.5	(3.9)
Parent Guarantor
Supplemental Guarantor Financial Information Statement of Operations [Line Items]
Sales									1,423.8	1,330.3	1,321.3
Cost of goods sold									1,153.1	1,195.5	1,153
Selling and administration									206	157	162.1
Restructuring charges									0	1.7	0.8
Acquisition-related costs									1	12.8	47.4
Other operating (loss) income									(3)	(11.1)	(2.2)
Operating income (loss)									(60.7)	47.8	44.2
Earnings (losses) of non-consolidated affiliates									(19.7)	1.8	1.7
Equity income in subsidiaries									310.7	638.4	16.2
Interest expense									68.6	44.5	38.8
Interest income									5.8	6.3	4.7
Non-operating pension income (expense)									26.6	38.5	48.3
Income (loss) before taxes									315.5	592.7	(12.1)
Income tax (benefit) provision									(12.4)	43.2	(8.2)
Net income (loss)									327.9	549.5	(3.9)
Issuer
Supplemental Guarantor Financial Information Statement of Operations [Line Items]
Sales									0	0	0
Cost of goods sold									0	0	0
Selling and administration									0	0	0
Restructuring charges									0	0	0
Acquisition-related costs									0	0	0
Other operating (loss) income									0	0	0
Operating income (loss)									0	0	0
Earnings (losses) of non-consolidated affiliates									0	0	0
Equity income in subsidiaries									289.6	357.6	139
Interest expense									153.3	165.8	153.9
Interest income									0	0	0
Non-operating pension income (expense)									0	0	0
Income (loss) before taxes									136.3	191.8	(14.9)
Income tax (benefit) provision									(35.1)	(310)	(57.6)
Net income (loss)									171.4	501.8	42.7
Subsidiary Non-Guarantor
Supplemental Guarantor Financial Information Statement of Operations [Line Items]
Sales									5,937	5,344.9	4,720.2
Cost of goods sold									5,083.7	4,766.2	4,282.4
Selling and administration									224.6	212.8	185.1
Restructuring charges									21.9	35.9	112.1
Acquisition-related costs									0	0	1.4
Other operating (loss) income									9.4	14.4	12.8
Operating income (loss)									(616.2)	(344.4)	(152)
Earnings (losses) of non-consolidated affiliates									0	0	0
Equity income in subsidiaries									0	0	0
Interest expense									26.9	13	4.7
Interest income									1.4	1.4	4.2
Non-operating pension income (expense)									(4.9)	(4.1)	(3.5)
Income (loss) before taxes									585.8	328.7	148
Income tax (benefit) provision									156.9	(165.5)	35.5
Net income (loss)									428.9	494.2	112.5
Eliminations
Supplemental Guarantor Financial Information Statement of Operations [Line Items]
Sales									(414.7)	(406.8)	(490.9)
Cost of goods sold									(414.7)	(406.8)	(490.9)
Selling and administration									0	0	0
Restructuring charges									0	0	0
Acquisition-related costs									0	0	0
Other operating (loss) income									0	0	0
Operating income (loss)									0	0	0
Earnings (losses) of non-consolidated affiliates									0	0	0
Equity income in subsidiaries									(600.3)	(996)	(155.2)
Interest expense									(5.6)	(5.9)	(5.5)
Interest income									(5.6)	(5.9)	(5.5)
Non-operating pension income (expense)									0	0	0
Income (loss) before taxes									(600.3)	(996)	(155.2)
Income tax (benefit) provision									0	0	0
Net income (loss)									$ (600.3)	$ (996)	$ (155.2)

SUPPLEMENTAL GUARANTOR FINANC_6

SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION (Statements of Comprehensive Income)(Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Guarantor Financial Information Statements Of Comprehensive Income [Line Items]
Net income (loss)	$ 53.3	$ 195.1	$ 58.6	$ 20.9	$ 489.3	$ 52.7	$ (5.9)	$ 13.4	$ 327.9	$ 549.5	$ (3.9)
Foreign currency translation adjustments, net									(22.2)	31.7	(12)
Unrealized (losses) gains on derivative contracts, net									(11.7)	(1.7)	19.7
Pension and postretirement liability adjustments, net									(74.9)	(21.6)	(37.5)
Amortization of prior service costs and actuarial losses, net									28.3	17	12.3
Total other comprehensive (loss) income, net of tax									(80.5)	25.4	(17.5)
Comprehensive income (loss)									247.4	574.9	(21.4)
Parent Guarantor
Supplemental Guarantor Financial Information Statements Of Comprehensive Income [Line Items]
Net income (loss)									327.9	549.5	(3.9)
Foreign currency translation adjustments, net									0	0	0
Unrealized (losses) gains on derivative contracts, net									(11.7)	(1.7)	19.7
Pension and postretirement liability adjustments, net									(69.6)	(12.3)	(25.3)
Amortization of prior service costs and actuarial losses, net									26.3	15.3	10.9
Total other comprehensive (loss) income, net of tax									(55)	1.3	5.3
Comprehensive income (loss)									272.9	550.8	1.4
Issuer
Supplemental Guarantor Financial Information Statements Of Comprehensive Income [Line Items]
Net income (loss)									171.4	501.8	42.7
Foreign currency translation adjustments, net									0	0	0
Unrealized (losses) gains on derivative contracts, net									0	0	0
Pension and postretirement liability adjustments, net									0	0	0
Amortization of prior service costs and actuarial losses, net									0	0	0
Total other comprehensive (loss) income, net of tax									0	0	0
Comprehensive income (loss)									171.4	501.8	42.7
Subsidiary Non-Guarantor
Supplemental Guarantor Financial Information Statements Of Comprehensive Income [Line Items]
Net income (loss)									428.9	494.2	112.5
Foreign currency translation adjustments, net									(22.2)	31.7	(12)
Unrealized (losses) gains on derivative contracts, net									0	0	0
Pension and postretirement liability adjustments, net									(5.3)	(9.3)	(12.2)
Amortization of prior service costs and actuarial losses, net									2	1.7	1.4
Total other comprehensive (loss) income, net of tax									(25.5)	24.1	(22.8)
Comprehensive income (loss)									403.4	518.3	89.7
Eliminations
Supplemental Guarantor Financial Information Statements Of Comprehensive Income [Line Items]
Net income (loss)									(600.3)	(996)	(155.2)
Foreign currency translation adjustments, net									0	0	0
Unrealized (losses) gains on derivative contracts, net									0	0	0
Pension and postretirement liability adjustments, net									0	0	0
Amortization of prior service costs and actuarial losses, net									0	0	0
Total other comprehensive (loss) income, net of tax									0	0	0
Comprehensive income (loss)									$ (600.3)	$ (996)	$ (155.2)

SUPPLEMENTAL GUARANTOR FINANC_7

SUPPLEMENTAL GUARANTOR FINANCIAL INFORMATION (Cash Flows)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net cash provided by (used for) operating activities	$ 907.8	$ 648.8	$ 603.2
Capital expenditures	(385.2)	(294.3)	(278)
Business acquired and related transactions, net of cash acquired	0	0	(69.5)
Payments under long-term supply contracts	0	(209.4)	(175.7)
Proceeds from sale/leaseback of equipment	0		40.4
Proceeds from disposition of property, plant and equipment	2.9	5.2	0.5
Proceeds from disposition of affiliated companies	0	0	8.8
Distributions from consolidated subsidiaries, net	0	0
Net investing activities	(382.3)	(498.5)	(473.5)
Long-term debt:
Borrowings	570	2,035.5	230
Repayments	(946.1)	(2,037.9)	(435.3)
Common stock repurchased and retired	(50)	0	0
Stock options exercised	3.4	29.8	0.5
Excess tax benefits from stock-based compensation	0	0	0.4
Dividends paid	(133.6)	(133)	(132.1)
Debt issuance costs	(8.5)	(11.2)	(1)
Intercompany financing activities	0	0	0
Net financing activities	(564.8)	(116.8)	(337.5)
Effect of exchange rate changes on cash and cash equivalents	(0.3)	0.4	0.3
Net (decrease) increase in cash and cash equivalents	(39.6)	33.9	(207.5)
Cash and cash equivalents, beginning of year	218.4	184.5	392
Cash and cash equivalents, end of year	178.8	218.4	184.5
Parent Guarantor
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net cash provided by (used for) operating activities	529.8	472	702.6
Capital expenditures	(149.8)	(89.1)	(65.7)
Business acquired and related transactions, net of cash acquired			(69.5)
Payments under long-term supply contracts		0	0
Proceeds from sale/leaseback of equipment			0
Proceeds from disposition of property, plant and equipment	0	0	0.2
Proceeds from disposition of affiliated companies			8.8
Distributions from consolidated subsidiaries, net	95	2.7
Net investing activities	(54.8)	(86.4)	(126.2)
Long-term debt:
Borrowings	550	620	0
Repayments	(21)	(690.8)	(335.6)
Common stock repurchased and retired	(50)
Stock options exercised	3.4	29.8	0.5
Excess tax benefits from stock-based compensation			0.4
Dividends paid	(133.6)	(133)	(132.1)
Debt issuance costs	(8.5)	(8.3)	0
Intercompany financing activities	(780.4)	(171.4)	(203.8)
Net financing activities	(440.1)	(353.7)	(670.6)
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net (decrease) increase in cash and cash equivalents	34.9	31.9	(94.2)
Cash and cash equivalents, beginning of year	57.1	25.2	119.4
Cash and cash equivalents, end of year	92	57.1	25.2
Issuer
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net cash provided by (used for) operating activities	0	0	0
Capital expenditures	0	0	0
Business acquired and related transactions, net of cash acquired			0
Payments under long-term supply contracts		0	0
Proceeds from sale/leaseback of equipment			0
Proceeds from disposition of property, plant and equipment	0	0	0
Proceeds from disposition of affiliated companies			0
Distributions from consolidated subsidiaries, net	95	0
Net investing activities	95	0	0
Long-term debt:
Borrowings	0	1,375	0
Repayments	(780.4)	(1,334.1)	(67.5)
Common stock repurchased and retired	0
Stock options exercised	0	0	0
Excess tax benefits from stock-based compensation			0
Dividends paid	(95)	0	0
Debt issuance costs	0	(2.9)	(1)
Intercompany financing activities	780.4	(38)	68.5
Net financing activities	(95)	0	0
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net (decrease) increase in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of year	0	0	0
Cash and cash equivalents, end of year	0	0	0
Subsidiary Non-Guarantor
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net cash provided by (used for) operating activities	378	176.8	(99.4)
Capital expenditures	(235.4)	(205.2)	(212.3)
Business acquired and related transactions, net of cash acquired			0
Payments under long-term supply contracts		(209.4)	(175.7)
Proceeds from sale/leaseback of equipment			40.4
Proceeds from disposition of property, plant and equipment	2.9	5.2	0.3
Proceeds from disposition of affiliated companies			0
Distributions from consolidated subsidiaries, net	0	0
Net investing activities	(232.5)	(409.4)	(347.3)
Long-term debt:
Borrowings	20	40.5	230
Repayments	(144.7)	(13)	(32.2)
Common stock repurchased and retired	0
Stock options exercised	0	0	0
Excess tax benefits from stock-based compensation			0
Dividends paid	(95)	(2.7)	0
Debt issuance costs	0	0	0
Intercompany financing activities	0	209.4	135.3
Net financing activities	(219.7)	234.2	333.1
Effect of exchange rate changes on cash and cash equivalents	(0.3)	0.4	0.3
Net (decrease) increase in cash and cash equivalents	(74.5)	2	(113.3)
Cash and cash equivalents, beginning of year	161.3	159.3	272.6
Cash and cash equivalents, end of year	86.8	161.3	159.3
Eliminations
Supplemental Guarantor Financial Information Statements Of Cash Flows [Line Items]
Net cash provided by (used for) operating activities	0	0	0
Capital expenditures	0	0	0
Business acquired and related transactions, net of cash acquired			0
Payments under long-term supply contracts		0	0
Proceeds from sale/leaseback of equipment			0
Proceeds from disposition of property, plant and equipment	0	0	0
Proceeds from disposition of affiliated companies			0
Distributions from consolidated subsidiaries, net	(190)	(2.7)
Net investing activities	(190)	(2.7)	0
Long-term debt:
Borrowings	0	0	0
Repayments	0	0	0
Common stock repurchased and retired	0
Stock options exercised	0	0	0
Excess tax benefits from stock-based compensation			0
Dividends paid	190	2.7	0
Debt issuance costs	0	0	0
Intercompany financing activities	0	0	0
Net financing activities	190	2.7	0
Effect of exchange rate changes on cash and cash equivalents	0	0	0
Net (decrease) increase in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of year	0	0	0
Cash and cash equivalents, end of year	$ 0	$ 0	$ 0

OTHER FINANCIAL DATA (Details)

OTHER FINANCIAL DATA (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Sales	$ 1,635	$ 1,872.4	$ 1,728.4	$ 1,710.3	$ 1,619.9	$ 1,554.9	$ 1,526.5	$ 1,567.1	$ 6,946.1	$ 6,268.4	$ 5,550.6
Cost of goods sold	1,391	1,441.7	1,460.7	1,528.7	1,400.2	1,349.3	1,407.9	1,397.5	5,822.1	5,554.9	4,944.5
Net income (loss)	$ 53.3	$ 195.1	$ 58.6	$ 20.9	$ 489.3	$ 52.7	$ (5.9)	$ 13.4	$ 327.9	$ 549.5	$ (3.9)
Earnings per Share, Basic [Abstract]
Basic net income (loss) per share (in dollars per share)	$ 0.32	$ 1.17	$ 0.35	$ 0.13	$ 2.93	$ 0.32	$ (0.04)	$ 0.08	$ 1.97	$ 3.31	$ (0.02)
Earnings per Share, Diluted [Abstract]
Diluted net income (loss) per share (in dollars per share)	0.32	1.16	0.35	0.12	2.89	0.31	(0.04)	0.08	1.95	3.26	$ (0.02)
Common dividends per share (in dollars per share)	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 0.80	$ 0.80