Olin (OLN) 10-Q 28 Jul 21 2021 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information	6 Months Ended
	Jun. 30, 2021shares
Cover [Abstract]
Entity Registrant Name	Olin Corporation
Entity Central Index Key	0000074303
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Document Transition Report	false
Entity File Number	1-1070
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	13-1872319
Entity Address, Address Line One	190 Carondelet Plaza,
Entity Address, Address Line Two	Suite 1530,
Entity Address, City or Town	Clayton,
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63105
City Area Code	314
Local Phone Number	480-1400
Title of 12(b) Security	Common Stock, $1.00 par value per share
Trading Symbol	OLN
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	160,462,045

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Current assets:
Cash and cash equivalents	$ 272.8	$ 189.7	$ 237.9
Receivables, net	1,033.7	770.9	700.2
Income taxes receivable	62.4	15.1	17.6
Inventories, net	736.5	674.7	619.1
Other current assets	112.7	66.7	42
Total current assets	2,218.1	1,717.1	1,616.8
Property, plant and equipment (less accumulated depreciation of $3,893.8, $3,719.8 and $3,484.9)	3,005.6	3,171	3,234.9
Operating lease assets, net	370.7	360.7	371.8
Deferred income taxes	111	11.2	38.3
Other assets	1,165.9	1,191.3	1,179.7
Intangible assets, net	365.7	399.4	416.9
Goodwill	1,420.2	1,420.2	2,119.7
Total assets	8,657.2	8,270.9	8,978.1
Current liabilities:
Current installments of long-term debt	1.1	26.3	1.8
Accounts payable	806.3	729.2	520.8
Income taxes payable	35.1	10.7	7.7
Current operating lease liabilities	76.9	74.7	77.3
Accrued liabilities	426.3	358	318.7
Total current liabilities	1,345.7	1,198.9	926.3
Long-term debt	3,381.8	3,837.5	4,073.9
Operating lease liabilities	299.8	291.6	299.2
Accrued pension liability	683.2	733.3	768
Deferred income taxes	521.9	443.2	414.5
Other liabilities	350.1	315.6	307.3
Total liabilities	6,582.5	6,820.1	6,789.2
Commitments and contingencies
Shareholders’ equity:
Common stock, $1.00 par value per share:  authorized, 240.0 shares; issued and outstanding, 160.5, 158.0 and 157.9 shares	160.5	158	157.9
Additional paid-in capital	2,187.9	2,137.8	2,127
Accumulated other comprehensive loss	(654.3)	(689.9)	(773.9)
Retained earnings (accumulated deficit)	380.6	(155.1)	677.9
Total shareholders’ equity	2,074.7	1,450.8	2,188.9
Total liabilities and shareholders’ equity	$ 8,657.2	$ 8,270.9	$ 8,978.1

Condensed Balance Sheets Parent

Condensed Balance Sheets Parenthetical - USD ($) shares in Millions, $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Assets
Accumulated depreciation	$ 3,893.8	$ 3,719.8	$ 3,484.9
Shareholders' equity:
Common stock, par value	$ 1	$ 1	$ 1
Common stock, authorized (in shares)	240	240	240
Common stock, issued	160.5	158	157.9
Common stock, outstanding	160.5	158	157.9

Condensed Statements of Operati

Condensed Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Sales	$ 2,221.3	$ 1,241.2	$ 4,140.1	$ 2,666.3
Operating expenses:
Cost of goods sold	1,712.2	1,235.7	3,136	2,609.9
Selling and administration	100.6	99.7	207.5	196.4
Restructuring charges	14	1.7	20.9	3.4
Other operating income	0.5	0.1	0.5	0.1
Operating income (loss)	395	(95.8)	776.2	(143.3)
Interest expense	65.9	69.4	150.4	132.5
Interest income	0	0.2	0.1	0.3
Non-operating pension income	(8.2)	(4.9)	(17.5)	(9.5)
Income (loss) before taxes	337.3	(160.1)	643.4	(266)
Income tax (benefit) provision	(18.5)	(40)	44	(65.9)
Net income (loss)	$ 355.8	$ (120.1)	$ 599.4	$ (200.1)
Net income (loss) per common share:
Basic	$ 2.23	$ (0.76)	$ 3.77	$ (1.27)
Diluted	$ 2.17	$ (0.76)	$ 3.69	$ (1.27)
Average common shares outstanding:
Basic	159.9	157.9	159.2	157.8
Diluted	163.8	157.9	162.3	157.8

Condensed Statements of Compreh

Condensed Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income (loss)	$ 355.8	$ (120.1)	$ 599.4	$ (200.1)
Other comprehensive income, net of tax:
Foreign currency translation adjustments, net	2.4	8.2	(9)	(0.8)
Unrealized gains on derivative contracts, net	16.3	30	23.3	12.1
Amortization of prior service costs and actuarial losses, net	10.7	9	21.3	18.2
Total other comprehensive income, net of tax	29.4	47.2	35.6	29.5
Comprehensive income (loss)	$ 385.2	$ (72.9)	$ 635	$ (170.6)

Condensed Statements of Shareho

Condensed Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Balance at Dec. 31, 2019		$ 157.7	$ 2,122.1	$ (803.4)	$ 941.1
Common stock issued for stock options exercised	$ 0.5	0	0.5
Common stock issued for other transactions		0.2	3.1
Stock-based compensation			1.3
Other comprehensive income	29.5			29.5
Net income (loss)	(200.1)				(200.1)
Common stock dividends paid					(63.1)
Balance at Jun. 30, 2020	2,188.9	$ 157.9	2,127	(773.9)	677.9
Dividends declared per share of common stock		$ 0.40
Balance at Mar. 31, 2020		$ 157.8	2,122.8	(821.1)	829.6
Common stock issued for stock options exercised		0	0
Common stock issued for other transactions		0.1	0.3
Stock-based compensation			3.9
Other comprehensive income	47.2			47.2
Net income (loss)	(120.1)				(120.1)
Common stock dividends paid					(31.6)
Balance at Jun. 30, 2020	2,188.9	$ 157.9	2,127	(773.9)	677.9
Dividends declared per share of common stock		$ 0.20
Balance at Dec. 31, 2020	1,450.8	$ 158	2,137.8	(689.9)	(155.1)
Common stock issued for stock options exercised	50.2	2.4	47.8
Common stock issued for other transactions		0.1	2.6
Stock-based compensation			(0.3)
Other comprehensive income	35.6			35.6
Net income (loss)	599.4				599.4
Common stock dividends paid					(63.7)
Balance at Jun. 30, 2021	2,074.7	$ 160.5	2,187.9	(654.3)	380.6
Dividends declared per share of common stock		$ 0.40
Balance at Mar. 31, 2021		$ 159.2	2,164.3	(683.7)	56.8
Common stock issued for stock options exercised		1.2	23.3
Common stock issued for other transactions		0.1	1.2
Stock-based compensation			(0.9)
Other comprehensive income	29.4			29.4
Net income (loss)	355.8				355.8
Common stock dividends paid					(32)
Balance at Jun. 30, 2021	$ 2,074.7	$ 160.5	$ 2,187.9	$ (654.3)	$ 380.6
Dividends declared per share of common stock		$ 0.20

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating Activities
Net income (loss)	$ 599.4	$ (200.1)
Adjustments to reconcile net income (loss) to net cash and cash equivalents provided by (used for) operating activities:
Stock-based compensation	1.3	4.1
Loss on debt extinguishment	38.9	0
Depreciation and amortization	287.2	283
Deferred income taxes	(26.8)	(52.1)
Qualified pension plan contributions	(0.6)	(1.2)
Qualified pension plan income	(13.7)	(5.9)
Change in:
Receivables	(274.5)	64.1
Income taxes receivable/payable	(22.6)	(15.8)
Inventories	(67.6)	75.7
Other current assets	12	(18.3)
Accounts payable and accrued liabilities	143.6	(74.9)
Other assets	(2.5)	0.6
Other noncurrent liabilities	32.2	(5.6)
Other operating activities	1.3	1.8
Net operating activities	707.6	55.4
Investing Activities
Capital expenditures	(86.4)	(166.5)
Payments under ethylene long-term supply contracts	0	461
Payments under other long-term supply contracts	0	75.8
Net investing activities	(86.4)	(703.3)
Long-term debt:
Borrowings	365	1,163.2
Repayments	(855.2)	(425.8)
Debt early redemption premiums	(31)	0
Stock options exercised	50.2	0.5
Dividends paid	(63.7)	(63.1)
Debt issuance costs	(3.1)	(9.6)
Net financing activities	(537.8)	665.2
Effect of exchange rate changes on cash and cash equivalents	(0.3)	(0.3)
Net increase in cash and cash equivalents	83.1	17
Cash and cash equivalents, beginning of year	189.7	220.9
Cash and cash equivalents, end of period	272.8	237.9
Cash paid for interest and income taxes:
Interest, net	153.5	122.3
Income taxes, net of refunds	82.6	3.1
Non-cash investing activities:
Decrease in capital expenditures included in accounts payable and accrued liabilities	$ 26.1	$ 38.6

DESCRIPTION OF BUSINESS

DESCRIPTION OF BUSINESS	6 Months Ended
	Jun. 30, 2021
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 (EDC) and vinyl chloride monomer, methyl chloride, methylene chloride, chloroform, carbon tetrachloride, perchloroethylene, trichloroethylene, hydrochloric acid, hydrogen, bleach products and potassium hydroxide. The Epoxy segment produces and sells a full range of epoxy materials and precursors, including aromatics (acetone, bisphenol, cumene and phenol), allyl chloride, epichlorohydrin, liquid epoxy resins, solid epoxy resins and downstream products such as converted epoxy resins and additives. The Winchester segment produces and sells sporting ammunition, reloading components, small caliber military ammunition and components, and industrial cartridges. We have prepared the condensed financial statements included herein, without audit, pursuant to the rules and regulations of the United States (U.S.) Securities and Exchange Commission (SEC). The preparation of the financial statements requires estimates and assumptions that affect amounts reported and disclosed in the financial statements and related notes. In our opinion, these financial statements reflect all adjustments (consisting only of normal accruals), which are necessary to present fairly the results for interim periods. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations; however, we believe that the disclosures are appropriate. We recommend that you read these condensed financial statements in conjunction with the financial statements, accounting policies and the notes thereto and Management’s Discussion and Analysis of Financial Condition and Results of Operations included in our Annual Report on Form 10-K for the year ended December 31, 2020. Certain reclassifications were made to prior year amounts to conform to the 2021 presentation.

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	6 Months Ended
	Jun. 30, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	NOTE 2. RECENT ACCOUNTING PRONOUNCEMENTSIn March 2020, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) 2020-04, “Facilitation of the Effects of Reference Rate Reform on Financial Reporting” (ASU 2020-04) which creates a new topic, Accounting Standards Codification (ASC) 848 “Reference Rate Reform.”  Subsequent to the issuance of ASU 2020-04, ASC 848 was amended by ASU 2021-01, “Scope” which amended and clarified the application and scope of the aforementioned update. This update provides optional guidance to ease the potential accounting burden associated with transition away from reference rates that are expected to be discontinued at the end of 2021, at which time financial institutions will no longer be required to report information that is currently used to determine the London Interbank Offered Rate (LIBOR) and other reference rates.  This update allows companies to treat contract amendments to existing contracts for the purpose of establishing a new reference rate as continuations of those contracts without additional analysis, as long as the modification was made to establish a new reference rate.  This update applies prospectively to contract modifications.  The optional guidance was effective on March 12, 2020 and can be adopted beginning January 1, 2020 or any date thereafter until December 31, 2022, at which time the optional guidance can no longer be applied to contract amendments to existing contracts. We adopted the provisions of this update on January 1, 2020 and will apply this guidance prospectively to contract modifications that are entered into for the purpose of establishing a new reference rate.  The adoption of this update did not have a material impact on our consolidated financial statements.

RESTRUCTURING CHARGES

RESTRUCTURING CHARGES	6 Months Ended
	Jun. 30, 2021
Restructuring and Related Activities [Abstract]
RESTRUCTURING CHARGES	NOTE 3. RESTRUCTURING CHARGES Olin committed to a productivity initiative to align the organization with our new operating model and improve efficiencies (collectively, Productivity Plan). These actions and related activities were completed during the second quarter of 2021. For both the three and six months ended June 30, 2021, we recorded pretax restructuring charges of $10.1 million for employee severance and related benefit costs related to these actions. We do not expect to incur additional restructuring charges related to these actions. On May 18, 2021, we announced that we had made the decision to permanently close approximately 20% of our diaphragm-grade chlor alkali capacity, representing 225,000 tons, at our Plaquemine, LA facility (Plaquemine Plan). The closure was completed in the second quarter of 2021. We expect to incur restructuring charges through 2022 of approximately $2 million related to this action. On March 15, 2021, we announced that we had made the decision to permanently close approximately 50% of our diaphragm-grade chlor alkali capacity, representing 200,000 tons, at our McIntosh, AL facility (McIntosh Plan). The closure was completed in the first quarter of 2021. For the three and six months ended June 30, 2021, we recorded pretax restructuring charges of $0.4 million and $4.8 million, respectively, for lease and other contract termination costs related to this action. We expect to incur additional restructuring charges through 2022 of approximately $2 million related to this action. On January 18, 2021, we announced that we had made the decision to permanently close our trichloroethylene and anhydrous hydrogen chloride liquefaction facilities in Freeport, TX (collectively, Freeport 2021 Plan), before the end of 2021. For the three and six months ended June 30, 2021, we recorded pretax restructuring charges of $2.8 million and $4.1 million, respectively, for facility exit costs related to these actions. We expect to incur additional restructuring charges through 2023 of approximately $25 million related to these actions. On December 11, 2019, we announced that we had made the decision to permanently close a chlor alkali plant with a capacity of 230,000 tons and our vinylidene chloride (VDC) production facility, both in Freeport, TX (collectively, Freeport 2019 Plan). The VDC facility and related chlor alkali plant were closed during fourth quarter of 2020 and second quarter of 2021, respectively. For the three months ended June 30, 2021 and 2020, we recorded pretax restructuring charges of $0.4 million and $0.5 million, respectively, for facility exit costs related to these actions. For the six months ended June 30, 2021 and 2020, we recorded pretax restructuring charges of $1.2 million and $0.5 million, respectively, for facility exit costs related to these actions. We expect to incur additional restructuring charges through 2025 of approximately $45 million related to these actions. 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 (collectively, Chlor Alkali 2016 Plan). 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 three months ended June 30, 2021 and 2020, we recorded pretax restructuring charges of $0.3 million and $1.2 million, respectively, for facility exit costs and lease and other contract termination costs related to these actions. For the six months ended June 30, 2021 and 2020, we recorded pretax restructuring charges of $0.7 million and $2.9 million, respectively, for facility exit costs, employee severance and related benefit costs and lease and other contract termination costs related to these actions. We expect to incur additional restructuring charges through 2021 of approximately $2 million related to these capacity reductions. The following table summarizes the 2021 and 2020 activities by major component of these restructuring actions and the remaining balances of accrued restructuring costs as of June 30, 2021 and 2020: Employee severance and related benefit costs Lease and other contract termination costs Facility exit costs Total ($ in millions) Balance at January 1, 2020 $ — $ 3.1 $ — $ 3.1 Restructuring charges: First quarter 0.1 0.1 1.5 1.7 Second quarter — — 1.7 1.7 Amounts utilized (0.1) (0.6) (3.2) (3.9) Balance at June 30, 2020 $ — $ 2.6 $ — $ 2.6 Balance at January 1, 2021 $ 1.8 $ 1.7 $ — $ 3.5 Restructuring charges: First quarter — 4.6 2.3 6.9 Second quarter 10.1 0.5 3.4 14.0 Amounts utilized (1.3) (0.7) (5.7) (7.7) Balance at June 30, 2021 $ 10.6 $ 6.1 $ — $ 16.7 The following table summarizes the cumulative restructuring charges of these restructuring actions by major component through June 30, 2021: Chlor Alkali Products and Vinyls Corporate/other Total Plaquemine Plan McIntosh Plan Freeport 2021 Plan Freeport 2019 Plan Chlor Alkali 2016 Plan Productivity Plan ($ in millions) Write-off of equipment and facility $ — $ — $ — $ 58.9 $ 78.1 $ — $ 137.0 Employee severance and related benefit costs — — — 2.1 6.7 10.1 18.9 Facility exit costs — — 4.1 2.9 52.4 — 59.4 Employee relocation costs — — — — 1.7 — 1.7 Lease and other contract termination costs — 4.8 — — 42.5 — 47.3 Total cumulative restructuring charges $ — $ 4.8 $ 4.1 $ 63.9 $ 181.4 $ 10.1 $ 264.3 As of June 30, 2021, we have incurred cash expenditures of $110.2 million and non-cash charges of $137.4 million related to these restructuring actions. The remaining balance of $16.7 million is expected to be paid out through 2031.

ACCOUNTS RECEIVABLES

ACCOUNTS RECEIVABLES	3 Months Ended
	Jun. 30, 2021
Receivables [Abstract]
ACCOUNTS RECEIVABLE	NOTE 4. ACCOUNTS RECEIVABLES We maintain a $250.0 million Receivables Financing Agreement (Receivables Financing Agreement) that is scheduled to mature on July 15, 2022. The Receivables Financing Agreement includes a minimum borrowing requirement of 50% of the facility limit or available borrowing capacity, whichever is less. The administrative agent for our Receivables Financing Agreement is PNC Bank, National Association. 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 secured leverage covenant that is contained in the $1,615.0 million senior secured credit facility. As of June 30, 2021, $457.9 million of our trade receivables were pledged as collateral. As of June 30, 2021, we had $125.0 million drawn with $125.0 million of additional borrowing capacity available under the Receivables Financing Agreement. As of December 31, 2020 and June 30, 2020, we had $125.0 million and $240.7 million, respectively, drawn 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 domestic subsidiaries may sell their accounts receivable up to a maximum of $228.0 million and certain of our foreign subsidiaries may sell their accounts receivable up to a maximum of €35.3 million. We will continue to service the outstanding accounts sold. These receivables qualify for sales treatment under ASC 860 “Transfers and Servicing” and, accordingly, the proceeds are included in net cash provided by operating activities in the condensed statements of cash flows. The following table summarizes the AR Facilities activity: June 30, 2021 2020 ($ in millions) Balance at beginning of year $ 48.8 $ 63.1 Gross receivables sold 487.3 457.5 Payments received from customers on sold accounts (450.4) (458.9) Balance at end of period $ 85.7 $ 61.7 The factoring discount paid under the AR Facilities is recorded as interest expense on the condensed statements of operations. The factoring discount was $0.3 million and $0.4 million for the three months ended June 30, 2021 and 2020, respectively, and $0.7 million and $1.0 million for the six months ended June 30, 2021 and 2020, respectively. The agreements are without recourse and therefore no recourse liability had been recorded as of June 30, 2021, December 31, 2020 or June 30, 2020.

INVENTORIES

INVENTORIES	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
INVENTORIES	NOTE 5. INVENTORIES Inventories consisted of the following: June 30, 2021 December 31, June 30, 2020 ($ in millions) Supplies $ 115.0 $ 113.8 $ 111.6 Raw materials 145.1 116.3 64.6 Work in process 145.1 133.2 94.0 Finished goods 420.9 359.6 392.7 Inventories excluding LIFO reserve 826.1 722.9 662.9 LIFO reserve (89.6) (48.2) (43.8) Inventories, net $ 736.5 $ 674.7 $ 619.1 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. Cost for other inventories has been determined principally by the average-cost method (primarily operating supplies, spare parts and maintenance parts). Elements of costs in inventories included raw materials, direct labor and manufacturing overhead. Inventories under the LIFO method are based on annual estimates of quantities and costs as of year-end; therefore, the condensed financial statements at June 30, 2021 reflect certain estimates relating to inventory quantities and costs at December 31, 2021. The replacement cost of our inventories would have been approximately $89.6 million, $48.2 million and $43.8 million higher than reported at June 30, 2021, December 31, 2020 and June 30, 2020, respectively.

OTHER ASSETS

OTHER ASSETS	6 Months Ended
	Jun. 30, 2021
Other Assets [Abstract]
OTHER ASSETS	NOTE 6. OTHER ASSETS Included in other assets were the following: June 30, 2021 December 31, 2020 June 30, 2020 ($ in millions) Supply contracts $ 1,091.0 $ 1,122.9 $ 1,137.9 Other 74.9 68.4 41.8 Other assets $ 1,165.9 $ 1,191.3 $ 1,179.7 We have entered into various arrangements for the long-term supply of ethylene and electricity. A payment of $461.0 million was made during the second quarter of 2020 associated with a previously executed option to reserve additional ethylene at producer economics from The Dow Chemical Company (Dow). The original liability was discounted and recorded at present value as of March 31, 2017. For the six months ended June 30, 2020, $4.0 million of interest expense was recorded for accretion on the 2020 payment liability discount. During the six months ended June 30, 2020, a payment of $75.8 million was made associated with the resolution of a dispute over the allocation to Olin of certain capital costs incurred at our Plaquemine, LA site after the October 5, 2015 closing date of the acquisition from Dow. Amortization expense of $17.3 million and $11.0 million for the three months ended June 30, 2021 and 2020, respectively, and amortization expense of $34.8 million and $33.3 million for the six months ended June 30, 2021 and 2020, respectively, was recognized within cost of goods sold related to our long-term supply contracts and is reflected in depreciation and amortization on the condensed statements of cash flows. The long-term supply contracts are monitored for impairment each reporting period.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLES	NOTE 7. 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, 2020 $ 1,832.7 $ 287.0 $ 2,119.7 Foreign currency translation adjustment — — — Balance at June 30, 2020 $ 1,832.7 $ 287.0 $ 2,119.7 Balance at January 1, 2021 (1) $ 1,275.3 $ 144.9 $ 1,420.2 Foreign currency translation adjustment — — — Balance at June 30, 2021 (1) $ 1,275.3 $ 144.9 $ 1,420.2 (1) The Chlor Alkali Products and Vinyls, Epoxy and total goodwill balances are net of $557.6 million, $142.2 million and $699.8 million of accumulated impairment losses recorded during the third quarter of 2020. Intangible assets consisted of the following: June 30, 2021 December 31, 2020 June 30, 2020 Gross Amount Accumulated Amortization Net Gross Amount Accumulated Amortization Net Gross Amount Accumulated Amortization Net ($ in millions) Customers, customer contracts and relationships $ 678.2 $ (336.3) $ 341.9 $ 681.0 $ (312.5) $ 368.5 $ 673.3 $ (285.3) $ 388.0 Trade name — — — — — — 7.0 (6.7) 0.3 Acquired technology 94.5 (71.9) 22.6 95.0 (65.3) 29.7 85.1 (57.7) 27.4 Other 1.8 (0.6) 1.2 1.8 (0.6) 1.2 1.8 (0.6) 1.2 Total intangible assets $ 774.5 $ (408.8) $ 365.7 $ 777.8 $ (378.4) $ 399.4 $ 767.2 $ (350.3) $ 416.9

EARNINGS PER SHARE

EARNINGS PER SHARE	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
EARNINGS PER SHARE	NOTE 8. EARNINGS PER SHARE Basic and diluted net 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. Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Computation of Net Income (Loss) per Share (In millions, except per share data) Net income (loss) $ 355.8 $ (120.1) $ 599.4 $ (200.1) Basic shares 159.9 157.9 159.2 157.8 Basic net income (loss) per share $ 2.23 $ (0.76) $ 3.77 $ (1.27) Diluted shares: Basic shares 159.9 157.9 159.2 157.8 Stock-based compensation 3.9 — 3.1 — Diluted shares 163.8 157.9 162.3 157.8 Diluted net income (loss) per share $ 2.17 $ (0.76) $ 3.69 $ (1.27) The computation of dilutive shares does not include less than 0.1 million and 10.3 million shares for the three months ended June 30, 2021 and 2020, respectively, and 1.1 million and 10.3 million shares for the six months ended June 30, 2021 and 2020, respectively, as their effect would have been anti-dilutive.

ENVIRONMENTAL

ENVIRONMENTAL	6 Months Ended
	Jun. 30, 2021
Environmental Remediation Obligations [Abstract]
ENVIRONMENTAL	NOTE 9. ENVIRONMENTAL We are party to various government and private environmental actions associated with past manufacturing facilities and former waste disposal sites. Environmental provisions charged to income, which are included in costs of goods sold, were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 ($ in millions) Provisions charged to income $ 4.7 $ 2.8 $ 7.2 $ 5.4 Recoveries for costs incurred and expensed — — (2.2) — Environmental expense $ 4.7 $ 2.8 $ 5.0 $ 5.4 Environmental expense for the six months ended June 30, 2021 includes $2.2 million of insurance recoveries for environmental costs incurred and expensed in prior periods. The condensed balance sheets included reserves for future environmental expenditures to investigate and remediate known sites amounting to $148.4 million, $147.2 million and $138.6 million at June 30, 2021, December 31, 2020 and June 30, 2020, respectively, of which $129.4 million, $128.2 million and $121.6 million, respectively, were classified as other noncurrent liabilities. 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.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 10. COMMITMENTS AND CONTINGENCIES Olin, K.A. Steel Chemicals (a wholly owned subsidiary of Olin) and other caustic soda producers were named as defendants in six purported class action civil lawsuits filed March 22, 25 and 26, 2019 and April 12, 2019 in the U.S. District Court for the Western District of New York on behalf of the respective named plaintiffs and a putative class comprised of all persons and entities who purchased caustic soda in the U.S. directly from one or more of the defendants, their parents, predecessors, subsidiaries or affiliates at any time on or after October 1, 2015. Olin, K.A. Steel Chemicals and other caustic soda producers were also named as defendants in two purported class action civil lawsuits filed July 25 and 29, 2019 in the U.S. District Court for the Western District of New York on behalf of the respective named plaintiffs and a putative class comprised of all persons and entities who purchased caustic soda in the U.S. indirectly from distributors at any time on or after October 1, 2015. The other current defendants in the lawsuits are Occidental Chemical Corporation d/b/a OxyChem, Westlake Chemical Corporation, Shin-Etsu Chemical Co., Ltd., and Formosa Plastics Corporation, U.S.A. The lawsuits allege the defendants conspired to fix, raise, maintain and stabilize the price of caustic soda, restrict domestic (U.S.) supply of caustic soda and allocate caustic soda customers. Plaintiffs seek an unspecified amount of damages and injunctive relief. Olin, K.A. Steel Chemical, Olin Canada ULC, 3229897 Nova Scotia Co. (wholly owned subsidiaries of Olin) and other alleged caustic soda producers were named as defendants in a proposed class action civil lawsuit filed on October 7, 2020 in the Quebec Superior Court (Province of Quebec) on behalf of the respective named plaintiff and a putative class comprised of all Canadian persons and entities who, between October 1, 2015 and the date of the eventual class action certification, directly or indirectly purchased caustic soda or products containing caustic soda, produced by one or more of the defendants. Olin, K.A. Steel Chemical, Olin Canada ULC, 3229897 Nova Scotia Co. and other alleged caustic soda producers were also named as defendants in a proposed class action civil lawsuit filed November 13, 2020 in the Federal Court of Canada on behalf of the respective named plaintiff and a putative class comprised of all legal persons in Canada who, at any time on or after October 1, 2015 to the present, directly or indirectly purchased caustic soda. The other defendants named in the two Canadian lawsuits are Occidental Petroleum Corporation, Occidental Chemical Corporation, Oxy Canada Sales, Inc., Westlake Chemical Corporation, Axiall Canada, Inc., Shin-Etsu Chemical Co., Ltd., Shintech Incorporated, Formosa Plastics Corporation, and Formosa Plastics Corporation, U.S.A. The lawsuits allege the defendants conspired to fix, raise, maintain control, and stabilize the price of caustic soda, divide and allocate markets, sales, customers and territories, fix, maintain, control, prevent, restrict, lessen or eliminate production and supply of caustic soda, and agree to idle capacity of production and/or refrain from increasing their production capacity. Plaintiffs seek an unspecified amount of damages, including punitive damages. We believe we have meritorious legal positions and will continue to represent our interests vigorously in this matter. Any losses related to this matter are not currently estimable because of unresolved questions of fact and law, but if resolved unfavorably to Olin, 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. As of June 30, 2021, December 31, 2020 and June 30, 2020, our condensed balance sheets included accrued liabilities for these other legal actions of $12.9 million, $13.5 million and $12.4 million, respectively. These liabilities do not include costs associated with legal representation. Based on our analysis, and considering the inherent uncertainties associated with litigation, we do not believe that it is reasonably possible that these other legal actions will materially adversely affect our financial position, cash flows or results of operations. 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.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	NOTE 11. 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. There were no shares repurchased for both the three and six months ended June 30, 2021 and 2020. As of June 30, 2021, we had repurchased a total of $195.9 million of our common stock, representing 10.1 million shares, and $304.1 million of common stock remained authorized to be repurchased. We issued 2.4 million and less than 0.1 million shares representing stock options exercised for the six months ended June 30, 2021 and 2020, respectively, with a total value of $50.2 million and $0.5 million, respectively. The following table represents the activity included in accumulated other comprehensive loss: Foreign Currency Translation Adjustment (net of taxes) Unrealized (Losses) Gains on Derivative Contracts (net of taxes) Pension and Other Postretirement Benefits (net of taxes) Accumulated Other Comprehensive Loss ($ in millions) Balance at January 1, 2020 $ (8.4) $ (13.6) $ (781.4) $ (803.4) Unrealized (losses) gains: First quarter (9.0) (35.1) — (44.1) Second quarter 8.2 29.9 — 38.1 Reclassification adjustments of losses into income: First quarter — 11.6 11.9 23.5 Second quarter — 9.3 11.6 20.9 Tax benefit (provision): First quarter — 5.6 (2.7) 2.9 Second quarter — (9.2) (2.6) (11.8) Net change (0.8) 12.1 18.2 29.5 Balance at June 30, 2020 $ (9.2) $ (1.5) $ (763.2) $ (773.9) Balance at January 1, 2021 $ 19.4 $ 21.4 $ (730.7) $ (689.9) Unrealized (losses) gains: First quarter (11.4) 122.0 — 110.6 Second quarter 2.4 41.8 — 44.2 Reclassification adjustments of (gains) losses into income: First quarter — (112.8) 13.7 (99.1) Second quarter — (20.4) 13.7 (6.7) Tax provision: First quarter — (2.2) (3.1) (5.3) Second quarter — (5.1) (3.0) (8.1) Net change (9.0) 23.3 21.3 35.6 Balance at June 30, 2021 $ 10.4 $ 44.7 $ (709.4) $ (654.3) Net income (loss) and cost of goods sold included reclassification adjustments for realized gains and losses on derivative contracts from accumulated other comprehensive loss.

SEGMENT INFORMATION

SEGMENT INFORMATION	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
SEGMENT INFORMATION	NOTE 12. SEGMENT INFORMATION We define segment results as income (loss) before interest expense, interest income, goodwill impairment charges, other operating income (expense), non-operating pension income, other income and income taxes. 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. Sales are attributed to geographic areas based on customer location. Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Sales: ($ in millions) Chlor Alkali Products and Vinyls $ 967.3 $ 651.2 $ 1,834.3 $ 1,411.1 Epoxy 850.0 397.4 1,512.6 874.6 Winchester 404.0 192.6 793.2 380.6 Total sales $ 2,221.3 $ 1,241.2 $ 4,140.1 $ 2,666.3 Income (loss) before taxes: Chlor Alkali Products and Vinyls $ 168.9 $ (57.0) $ 440.0 $ (91.3) Epoxy 165.3 (13.0) 230.5 (1.3) Winchester 109.9 16.0 195.0 26.5 Corporate/other: Environmental expense (4.7) (2.8) (5.0) (5.4) Other corporate and unallocated costs (30.9) (37.4) (63.9) (68.5) Restructuring charges (14.0) (1.7) (20.9) (3.4) Other operating income 0.5 0.1 0.5 0.1 Interest expense (65.9) (69.4) (150.4) (132.5) Interest income — 0.2 0.1 0.3 Non-operating pension income 8.2 4.9 17.5 9.5 Income (loss) before taxes $ 337.3 $ (160.1) $ 643.4 $ (266.0) Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Sales by geography: ($ in millions) Chlor Alkali Products and Vinyls United States $ 713.6 $ 450.3 $ 1,290.6 $ 984.2 Europe 39.4 26.8 68.9 57.0 Other foreign 214.3 174.1 474.8 369.9 Total Chlor Alkali Products and Vinyls 967.3 651.2 1,834.3 1,411.1 Epoxy United States 253.6 122.5 411.9 281.3 Europe 403.8 140.4 723.8 334.8 Other foreign 192.6 134.5 376.9 258.5 Total Epoxy 850.0 397.4 1,512.6 874.6 Winchester United States 373.6 178.6 738.6 352.7 Europe 6.3 2.3 10.1 4.8 Other foreign 24.1 11.7 44.5 23.1 Total Winchester 404.0 192.6 793.2 380.6 Total United States 1,340.8 751.4 2,441.1 1,618.2 Europe 449.5 169.5 802.8 396.6 Other foreign 431.0 320.3 896.2 651.5 Total sales $ 2,221.3 $ 1,241.2 $ 4,140.1 $ 2,666.3 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Sales by product line: ($ in millions) Chlor Alkali Products and Vinyls Caustic soda $ 400.8 $ 320.2 $ 747.8 $ 680.4 Chlorine, chlorine-derivatives and other co-products 566.5 331.0 1,086.5 730.7 Total Chlor Alkali Products and Vinyls 967.3 651.2 1,834.3 1,411.1 Epoxy Aromatics and allylics 366.5 167.0 678.5 384.4 Epoxy resins 483.5 230.4 834.1 490.2 Total Epoxy 850.0 397.4 1,512.6 874.6 Winchester Commercial 281.5 135.6 542.5 262.7 Military and law enforcement 122.5 57.0 250.7 117.9 Total Winchester 404.0 192.6 793.2 380.6 Total sales $ 2,221.3 $ 1,241.2 $ 4,140.1 $ 2,666.3

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	NOTE 13. STOCK-BASED COMPENSATION Stock-based compensation granted includes stock options, performance stock awards, restricted stock awards and deferred directors’ compensation. Stock-based compensation expense was as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 ($ in millions) Stock-based compensation $ 7.2 $ 4.3 $ 11.9 $ 6.3 Mark-to-market adjustments 6.0 (0.1) 14.1 (3.1) Total expense $ 13.2 $ 4.2 $ 26.0 $ 3.2 The fair value of each stock 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 weighted-average assumptions: Grant date 2021 Dividend yield 2.76 % Risk-free interest rate 0.94 % Expected volatility of Olin common stock 44 % Expected life (years) 7.0 Weighted-average grant fair value (per option) $ 9.91 Weighted-average exercise price $ 28.99 Options granted 1,094,700 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 of Olin common stock 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 of future exercise patterns. 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 are based on two criteria: (1) 50% of the award is based on Olin’s total shareholder returns (TSR) over the applicable three-year performance cycle in relation to the TSR 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. The fair value of each performance stock award based on net income was estimated on the date of grant, using the current stock price. The fair value of each performance stock award based on TSR was estimated on the date of grant, using a Monte Carlo simulation model with the following weighted average assumptions: Grant date 2021 Risk-free interest rate 0.23 % Expected volatility of Olin common stock 55 % Expected average volatility of peer companies 50 % Average correlation coefficient of peer companies 0.50 Expected life (years) 3.0 Grant date fair value (TSR based award) $ 39.96 Grant date fair value (net income based award) $ 28.99 Awards granted 248,700 Risk-free interest rate was based on zero coupon U.S. Treasury securities rates for the expected life of the performance stock awards. Expected volatility of Olin common stock and peer companies was based on historical stock price movements, as

DEBT

DEBT	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
DEBT	NOTE 14. DEBT During 2021, activity of our debt outstanding included: Long-term Debt Borrowings (Repayments) Loss on Debt Extinguishment (1) Six Months Ended June 30, 2021 Three Months Ended June 30, 2021 Six Months Ended June 30, 2021 Debt Instrument ($ in millions) Borrowings: Senior Secured Term Loans $ 315.0 Receivables Financing Agreement 50.0 Total borrowings $ 365.0 Repayments: 10.00% senior notes due 2025 $ (500.0) $ 11.3 $ 30.9 9.75% senior notes due 2023 (120.0) — 3.7 5.625% senior notes due 2029 (26.5) 2.9 2.9 5.00% senior notes due 2030 (8.0) 0.6 0.6 Senior Secured Term Loans (150.0) 0.6 0.8 Receivables Financing Agreement (50.0) — — Finance leases (0.7) — — Total repayments $ (855.2) $ 15.4 $ 38.9 Long-term debt repayments, net $ (490.2) (1) Loss on debt extinguishment is included as interest expense in the condensed statements of operations. The loss includes the payment of bond redemption premiums of $12.3 million and $31.0 million for the three and six months ended June 30, 2021, respectively, as well as the write-off of deferred debt issuance costs and recognition of deferred fair value interest rate swap losses of $3.1 million and $7.9 million for the three and six months ended June 30, 2021, respectively, associated with the optional prepayment of existing debt. The cash payments related to the early redemption premiums for the debt extinguishments are classified as cash outflows from financing activities on the condensed statement of cash flows for the six months ended June 30, 2021. The condensed statement of cash flows reflects a correction to the loss on debt extinguishment and early redemption premiums from the previously issued condensed statement of cash flows for the three months ended March 31, 2021, which increased cash flows from net operating activities and decreased cash flows from net financing activities by $18.7 million. During the fourth quarter of 2021, the previously issued statement of cash flows for the year ended December 31, 2020 will reflect the correction of previously presented early redemption premiums, which will increase cash flows from net operating activities and decrease cash flows from net financing activities by $14.6 million. On February 24, 2021, we entered into a $1,615.0 million senior secured credit facility (Senior Secured Credit Facility) that amended our existing $1,300.0 million senior secured credit facility. The Senior Secured Credit Facility includes a senior secured delayed-draw term loan facility with aggregate commitments of $315.0 million (Delayed Draw Term Loan), a senior secured term loan facility with aggregate commitments of $500.0 million (2020 Term Loan and together with the Delayed Draw Term Loan, the Senior Secured Term Loans) and a senior secured revolving credit facility with aggregate commitments in an amount equal to $800.0 million (Senior Revolving Credit Facility). The maturity date for the Senior Secured Credit Facility is July 16, 2024. The amendment modified the pricing grid for the Senior Secured Credit Facility by reducing applicable interest rates on the borrowings under the facility. On March 30, 2021, Olin drew the entire $315.0 million of the Delayed Draw Term Loan and used the proceeds to fund the redemption of the 10.00% senior notes due October 15, 2025. The Senior Secured Term Loans include principal amortization amounts payable beginning June 30, 2021 at a rate of 1.25% per quarter through the end of 2022, increasing to 1.875% per quarter during 2023 and 2.50% per quarter thereafter until maturity. During the six months ended June 30, 2021, we repaid $150.0 million of the Senior Secured Term Loans, of which $10.2 million was a required quarterly installment. These repayments eliminated the required quarterly installments of the Senior Secured Term Loans through December 2023. The Senior Revolving Credit Facility includes a $100.0 million letter of credit subfacility. At June 30, 2021, we had $799.6 million available under our $800.0 million Senior Revolving Credit Facility because we had issued $0.4 million of letters of credit. Annual maturities of long-term debt at June 30, 2021, including finance lease obligations, are $0.6 million in 2021, $326.1 million in 2022, $1.0 million in 2023, $735.8 million in 2024, $503.1 million in 2025 and a total of $1,848.5 million thereafter. For the six months ended June 30, 2021, we paid debt issuance costs of $3.1 million for the amendments to our Senior Secured Credit Facility. Under the Senior Secured Credit Facility, we may select various floating rate borrowing options. The actual interest rate paid on borrowings under the Senior Secured Credit Facility is based on a pricing grid which is dependent upon the net leverage ratio as calculated under the terms of the applicable facility for the prior fiscal quarter. The Senior Secured Credit Facility includes various customary restrictive covenants, including restrictions related to the ratio of secured debt to earnings before interest expense, taxes, depreciation and amortization (secured leverage ratio) and the ratio of earnings before interest expense, taxes, depreciation and amortization to interest expense (coverage ratio). The calculation of secured debt in our secured leverage ratio excludes borrowings under the Receivables Financing Agreement, up to a maximum of $250.0 million. As of June 30, 2021, the only secured borrowings included in the secured leverage ratio were $665.0 million for our Senior Secured Term Loans and $153.0 million for our Go Zone and Recovery Zone bonds. Compliance with these covenants is determined quarterly. We were in compliance with all covenants and restrictions under all our outstanding credit agreements as of June 30, 2021, 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 a result of our restrictive covenant related to the secured leverage ratio, the maximum additional borrowings available to us could be limited in the future. The limitation, if an amendment or waiver from our lenders is not obtained, could restrict our ability to borrow the maximum amounts available under the Senior Revolving Credit Facility and the Receivables Financing Agreement. As of June 30, 2021, there were no covenants or other restrictions that limited our ability to borrow.

CONTRIBUTING EMPLOYEE OWNERSHIP

CONTRIBUTING EMPLOYEE OWNERSHIP PLAN	6 Months Ended
	Jun. 30, 2021
Retirement Benefits [Abstract]
CONTRIBUTING EMPLOYEE OWNERSHIP PLAN	NOTE 15. 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 for the three months ended June 30, 2021 and 2020 was $8.6 million and $6.8 million, respectively, and for the six months ended June 30, 2021 and 2020 was $17.3 million and $15.0 million, respectively. Company matching contributions are invested in the same investment allocation as the employee’s contribution. Our matching contributions for eligible employees for the three months ended June 30, 2021 and 2020 were $3.7 million and $0.7 million, respectively, and for the six months ended June 30, 2021 and 2020 were $6.9 million and $1.5 million, respectively. Effective January 1, 2020, we suspended the match on all salaried and non-bargaining hourly employees’ contributions, and moved to a discretionary contribution model with contributions contingent upon company-wide financial performance. During 2020, we did not make a discretionary matching contribution. Effective January 1, 2021, we reinstated the match on all salaried and non-bargaining hourly employees’ contributions, which provides for a maximum 3.0% matching contribution based on the level of participant contributions.

PENSION PLANS AND RETIREMENT BE

PENSION PLANS AND RETIREMENT BENEFITS	6 Months Ended
	Jun. 30, 2021
Retirement Benefits [Abstract]
PENSION PLANS AND RETIREMENT BENEFITS	NOTE 16. PENSION PLANS AND RETIREMENT BENEFITS 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). We also 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. Pension Benefits Other Postretirement Benefits Three Months Ended June 30, Three Months Ended June 30, 2021 2020 2021 2020 Components of Net Periodic Benefit (Income) Cost ($ in millions) Service cost $ 2.8 $ 2.7 $ 0.3 $ 0.4 Interest cost 12.8 18.8 0.3 0.3 Expected return on plans’ assets (35.0) (35.6) — — Amortization of prior service cost (0.2) — 0.1 — Recognized actuarial loss 13.2 11.1 0.6 0.5 Net periodic benefit (income) cost $ (6.4) $ (3.0) $ 1.3 $ 1.2 Pension Benefits Other Postretirement Benefits Six Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Components of Net Periodic Benefit (Income) Cost ($ in millions) Service cost $ 5.8 $ 5.7 $ 0.7 $ 0.7 Interest cost 25.6 37.5 0.6 0.7 Expected return on plans’ assets (71.1) (71.2) — — Amortization of prior service cost (0.3) — 0.1 — Recognized actuarial loss 26.3 22.3 1.3 1.2 Net periodic benefit (income) cost $ (13.7) $ (5.7) $ 2.7 $ 2.6 We made cash contributions to our international qualified defined benefit pension plans of $0.6 million and $1.2 million for the six months ended June 30, 2021 and 2020, respectively.

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE 17. INCOME TAXES The effective tax rate for the three months ended June 30, 2021 included a benefit from a net decrease in the valuation allowance related to deferred tax assets in foreign jurisdictions, a benefit associated with prior year tax positions, a benefit associated with stock-based compensation and an expense from a change in tax contingencies. These factors resulted in a net $93.9 million tax benefit. After giving consideration to these items, the effective tax rate for the three months ended June 30, 2021 of 22.4% was higher than the 21% U.S. federal statutory rate primarily due to state taxes, foreign income inclusions and foreign income taxes, partially offset by a net decrease in the valuation allowance related to utilization of losses in foreign jurisdictions and favorable permanent salt depletion deductions. The effective tax rate for the three months ended June 30, 2020 of 25.0% was higher than the 21% U.S. federal statutory rate primarily due to state taxes, foreign income taxes and favorable permanent salt depletion deductions, partially offset by foreign income inclusions and a net increase in the valuation allowance related to losses in foreign jurisdictions. The effective tax rate for the six months ended June 30, 2021 included a benefit from a net decrease in the valuation allowance related to deferred tax assets in foreign jurisdictions, a benefit associated with prior year tax positions, a benefit associated with stock-based compensation, an expense from remeasurement of deferred taxes due to an increase in our state effective tax rates and an expense from a change in tax contingencies. These factors resulted in a net $95.2 million tax benefit. After giving consideration to these items, the effective tax rate for the six months ended June 30, 2021 of 21.6% was higher than the 21% U.S. federal statutory rate primarily due to state taxes, foreign income inclusions and foreign income taxes, partially offset by a net decrease in the valuation allowance related to utilization of losses in foreign jurisdictions and favorable permanent salt depletion deductions. The effective tax rate for the six months ended June 30, 2020 included an expense associated with stock-based compensation, an expense associated with prior year tax positions and an expense from a change in tax contingencies. These factors resulted in a net $1.0 million tax expense. After giving consideration to these items, the effective tax rate for the six months ended June 30, 2020 of 25.2% was higher than the 21% U.S. federal statutory rate primarily due to state taxes, foreign income taxes and favorable permanent salt depletion deductions, partially offset by foreign income inclusions and a net increase in the valuation allowance related to losses in foreign jurisdictions. During the three months ended June 30, 2021, we released the valuation allowance related to deferred tax assets of our German operations that resulted in a net tax benefit of $103.8 million. As a result of significant taxable income during the first six months of 2021, our German operations reported cumulative income before tax (adjusted for permanent items) over the previous twelve quarters. Additionally, we project taxable income in our German operations for the remainder of 2021 and we expect that net operating loss carryovers and other deductible amounts in Germany will ultimately be realizable against future income. We concluded, based upon the preponderance of positive evidence over negative evidence and the anticipated ability to use the deferred tax assets, that it was more likely than not that the deferred tax assets in Germany would be realizable due to U.S. GAAP forecasted income. If there are unfavorable changes to actual operating results or to projections of future income, we may determine that it is more likely than not such deferred tax assets may not be realizable. As of June 30, 2021, we had $40.8 million of gross unrecognized tax benefits, which would have a net $40.6 million impact on the effective tax rate, if recognized. As of June 30, 2020, we had $22.0 million of gross unrecognized tax benefits, of which $21.8 million would have impacted the effective tax rate, if recognized. The amount of unrecognized tax benefits was as follows: June 30, 2021 2020 ($ in millions) Balance at beginning of year $ 21.3 $ 22.8 Increases for prior year tax positions 20.5 — Decreases for prior year tax positions (3.8) (1.8) Increases for current year tax positions 2.8 1.0 Balance at end of period $ 40.8 $ 22.0 Increases for prior year tax positions primarily are the result of ongoing discussions with tax auditors in a major foreign jurisdiction during the second quarter of 2021. In April 2021, the review of certain U.S. income tax claims by the Internal Revenue Service for the year 2016 was finalized which resulted in a $3.8 million income tax benefit related to favorable adjustments in uncertain tax positions for prior tax years. As of June 30, 2021, we believe it is reasonably possible that our total amount of unrecognized tax benefits will decrease by approximately $15.6 million over the next twelve months. The anticipated reduction primarily relates to settlements with taxing 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. Examinations are ongoing in various states and foreign jurisdictions. 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 2017 - 2020 U.S. state income tax 2012 - 2020 Canadian federal income tax 2013 - 2020 Brazil 2015 - 2020 Germany 2015 - 2020 China 2014 - 2020 The Netherlands 2015 - 2020

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	NOTE 18. 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 “Derivatives and Hedging” (ASC 815) requires an entity to recognize all derivatives as either assets or liabilities in the condensed 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 risk to offset our net exposures, by currency, related to the foreign currency denominated monetary assets and liabilities of our operations. At June 30, 2021, we had outstanding forward contracts to buy foreign currency with a notional value of $270.8 million and to sell foreign currency with a notional value of $99.7 million. All of the currency derivatives expire within one year and are for U.S. dollar (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, 2020, we had outstanding forward contracts to buy foreign currency with a notional value of $169.9 million and to sell foreign currency with a notional value of $113.6 million. At June 30, 2020, we had outstanding forward contracts to buy foreign currency with a notional value of $176.6 million and to sell foreign currency with a notional value of $111.7 million. Cash Flow Hedges For derivative instruments that are designated and qualify as a cash flow hedge, the change in fair value of the derivative is recognized as a component of other comprehensive income (loss) until the hedged item is recognized in earnings. We had the following notional amounts of outstanding commodity contracts that were entered into to hedge forecasted purchases: June 30, 2021 December 31, 2020 June 30, 2020 ($ in millions) Natural gas $ 57.3 $ 74.1 $ 59.3 Ethane 44.8 51.8 48.2 Metals 148.7 88.2 117.6 Total notional $ 250.8 $ 214.1 $ 225.1 As of June 30, 2021, the counterparties to these commodity contracts were Wells Fargo Bank, N.A., Citibank, N.A., JPMorgan Chase Bank, National Association and Bank of America Corporation, 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 June 30, 2021, we had open derivative contract positions through 2027. If all open futures contracts had been settled on June 30, 2021, we would have recognized a pretax gain of $59.0 million. If commodity prices were to remain at June 30, 2021 levels, approximately $33.6 million of deferred gains, 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. 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. In August 2019, we terminated the interest rate swaps designated as fair value hedges which resulted in a loss of $2.3 million that was deferred as an offset to the carrying value of the related debt and was subsequently recognized to interest expense. In 2021, we redeemed the 2025 Notes, which resulted in recognition of the outstanding deferred swap loss. For the three months ended June 30, 2021 and June 30, 2020, $0.6 million and $0.1 million, respectively, and for the six months ended June 30, 2021 and June 30, 2020, $1.8 million and $0.2 million, respectively, of expense was recorded to interest expense on the accompanying condensed statements of operations related to these swap agreements. Financial Statement Impacts We present our derivative assets and liabilities in our condensed balance sheets on a net basis whenever we have a legally enforceable master netting agreement with the counterparty to our derivative contracts. We use these agreements to manage and substantially reduce our potential counterparty credit risk. The following table summarizes the location and fair value of the derivative instruments on our condensed balance sheets. The table disaggregates our net derivative assets and liabilities into gross components on a contract-by-contract basis before giving effect to master netting arrangements: June 30, 2021 December 31, 2020 June 30, 2020 ($ in millions) Asset derivatives: Other current assets Derivatives designated as hedging instruments: Commodity contracts - gains $ 45.5 $ 25.0 $ 5.1 Commodity contracts - losses (1.3) (3.1) (2.8) Derivatives not designated as hedging instruments: Foreign exchange contracts - gains — 2.5 5.3 Foreign exchange contracts - losses — (0.2) (2.9) Total other current assets 44.2 24.2 4.7 Other assets Derivatives designated as hedging instruments: Commodity contracts - gains 14.9 7.4 3.0 Commodity contracts - losses — (0.2) (0.7) Total other assets 14.9 7.2 2.3 Total asset derivatives (1) $ 59.1 $ 31.4 $ 7.0 Liability derivatives: Accrued liabilities Derivatives designated as hedging instruments: Commodity contracts - losses $ 0.7 $ 1.4 $ 8.8 Commodity contracts - gains (0.7) (1.3) (2.4) Derivatives not designated as hedging instruments: Foreign exchange contracts - losses 6.5 — 1.3 Foreign exchange contracts - gains (0.4) — (0.1) Total accrued liabilities 6.1 0.1 7.6 Other liabilities Derivatives designated as hedging instruments: Commodity contracts - losses — 0.8 0.2 Commodity contracts - gains — (0.2) (0.1) Total other liabilities — 0.6 0.1 Total liability derivatives (1) $ 6.1 $ 0.7 $ 7.7 (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 condensed statements of operations: Amount of Gain (Loss) Three Months Ended June 30, Six Months Ended June 30, Location of Gain (Loss) 2021 2020 2021 2020 Derivatives – Cash Flow Hedges ($ in millions) Recognized in other comprehensive loss: Commodity contracts ——— $ 41.8 $ 29.9 $ 163.8 $ (5.2) Reclassified from accumulated other comprehensive loss into income: Commodity contracts Cost of goods sold $ 20.4 $ (9.3) $ 133.2 $ (20.9) Derivatives – Fair Value Hedges Interest rate contracts Interest expense $ (0.6) $ (0.1) $ (1.8) $ (0.2) Derivatives Not Designated as Hedging Instruments Foreign exchange contracts Selling and administration $ (6.2) $ 0.6 $ (8.2) $ 7.1 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 June 30, 2021, December 31, 2020 and June 30, 2020, 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	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	NOTE 19. FAIR VALUE MEASUREMENTS 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 condensed 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 Measurements and Disclosures” (ASC 820) are directly related to the amount of subjectivity associated with the inputs to fair valuation of these assets and liabilities, and 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. 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. We evaluate our hierarchy disclosures each quarter. The following table summarizes the assets and liabilities measured at fair value in the condensed balance sheets: Fair Value Measurements Balance at June 30, 2021 Level 1 Level 2 Level 3 Total Assets ($ in millions) Commodity contracts $ — $ 59.1 $ — $ 59.1 Total Assets $ — $ 59.1 $ — $ 59.1 Liabilities Foreign exchange contracts $ — $ 6.1 $ — $ 6.1 Total Liabilities $ — $ 6.1 $ — $ 6.1 Balance at December 31, 2020 Assets Commodity contracts $ — $ 29.1 $ — $ 29.1 Foreign exchange contracts — 2.3 — 2.3 Total Assets $ — $ 31.4 $ — $ 31.4 Liabilities Commodity contracts $ — $ 0.7 $ — $ 0.7 Total Liabilities $ — $ 0.7 $ — $ 0.7 Balance at June 30, 2020 Assets Commodity contracts $ — $ 4.6 $ — $ 4.6 Foreign exchange contracts — 2.4 — 2.4 Total Assets $ — $ 7.0 $ — $ 7.0 Liabilities Commodity contracts $ — $ 6.5 $ — $ 6.5 Foreign exchange contracts — 1.2 — 1.2 Total Liabilities $ — $ 7.7 $ — $ 7.7 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. Since our long-term debt instruments may not be actively traded, the inputs used to measure the fair value of our long-term debt are based on current market rates for debt of similar risk and maturities and is classified as Level 2 in the fair value measurement hierarchy. As of June 30, 2021, December 31, 2020 and June 30, 2020, the fair value measurements of debt were $3,669.2 million, $4,177.2 million and $4,056.7 million, respectively. 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 or liabilities measured at fair value on a nonrecurring basis as of June 30, 2021, December 31, 2020 and June 30, 2020.

RESTRUCTURING CHARGES (Tables)

RESTRUCTURING CHARGES (Tables)	6 Months Ended
	Jun. 30, 2021
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Reserve by Type of Cost	The following table summarizes the 2021 and 2020 activities by major component of these restructuring actions and the remaining balances of accrued restructuring costs as of June 30, 2021 and 2020: Employee severance and related benefit costs Lease and other contract termination costs Facility exit costs Total ($ in millions) Balance at January 1, 2020 $ — $ 3.1 $ — $ 3.1 Restructuring charges: First quarter 0.1 0.1 1.5 1.7 Second quarter — — 1.7 1.7 Amounts utilized (0.1) (0.6) (3.2) (3.9) Balance at June 30, 2020 $ — $ 2.6 $ — $ 2.6 Balance at January 1, 2021 $ 1.8 $ 1.7 $ — $ 3.5 Restructuring charges: First quarter — 4.6 2.3 6.9 Second quarter 10.1 0.5 3.4 14.0 Amounts utilized (1.3) (0.7) (5.7) (7.7) Balance at June 30, 2021 $ 10.6 $ 6.1 $ — $ 16.7
Cumulative Restructuring Charges by Type and Plan	The following table summarizes the cumulative restructuring charges of these restructuring actions by major component through June 30, 2021: Chlor Alkali Products and Vinyls Corporate/other Total Plaquemine Plan McIntosh Plan Freeport 2021 Plan Freeport 2019 Plan Chlor Alkali 2016 Plan Productivity Plan ($ in millions) Write-off of equipment and facility $ — $ — $ — $ 58.9 $ 78.1 $ — $ 137.0 Employee severance and related benefit costs — — — 2.1 6.7 10.1 18.9 Facility exit costs — — 4.1 2.9 52.4 — 59.4 Employee relocation costs — — — — 1.7 — 1.7 Lease and other contract termination costs — 4.8 — — 42.5 — 47.3 Total cumulative restructuring charges $ — $ 4.8 $ 4.1 $ 63.9 $ 181.4 $ 10.1 $ 264.3

ACCOUNTS RECEIVABLES (Tables)

ACCOUNTS RECEIVABLES (Tables)	6 Months Ended
	Jun. 30, 2021
Receivables [Abstract]
AR Facilities	The following table summarizes the AR Facilities activity: June 30, 2021 2020 ($ in millions) Balance at beginning of year $ 48.8 $ 63.1 Gross receivables sold 487.3 457.5 Payments received from customers on sold accounts (450.4) (458.9) Balance at end of period $ 85.7 $ 61.7

INVENTORIES (Tables)

INVENTORIES (Tables)	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Inventories Table	Inventories consisted of the following: June 30, 2021 December 31, June 30, 2020 ($ in millions) Supplies $ 115.0 $ 113.8 $ 111.6 Raw materials 145.1 116.3 64.6 Work in process 145.1 133.2 94.0 Finished goods 420.9 359.6 392.7 Inventories excluding LIFO reserve 826.1 722.9 662.9 LIFO reserve (89.6) (48.2) (43.8) Inventories, net $ 736.5 $ 674.7 $ 619.1

OTHER ASSETS (Tables)

OTHER ASSETS (Tables)	6 Months Ended
	Jun. 30, 2021
Other Assets [Abstract]
Schedule of Other Assets	Included in other assets were the following: June 30, 2021 December 31, 2020 June 30, 2020 ($ in millions) Supply contracts $ 1,091.0 $ 1,122.9 $ 1,137.9 Other 74.9 68.4 41.8 Other assets $ 1,165.9 $ 1,191.3 $ 1,179.7

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Changes in the carrying value of goodwill were as follows: Chlor Alkali Products and Vinyls Epoxy Total ($ in millions) Balance at January 1, 2020 $ 1,832.7 $ 287.0 $ 2,119.7 Foreign currency translation adjustment — — — Balance at June 30, 2020 $ 1,832.7 $ 287.0 $ 2,119.7 Balance at January 1, 2021 (1) $ 1,275.3 $ 144.9 $ 1,420.2 Foreign currency translation adjustment — — — Balance at June 30, 2021 (1) $ 1,275.3 $ 144.9 $ 1,420.2 (1) The Chlor Alkali Products and Vinyls, Epoxy and total goodwill balances are net of $557.6 million, $142.2 million and $699.8 million of accumulated impairment losses recorded during the third quarter of 2020.
Schedule of Finite-Lived Intangible Assets	Intangible assets consisted of the following: June 30, 2021 December 31, 2020 June 30, 2020 Gross Amount Accumulated Amortization Net Gross Amount Accumulated Amortization Net Gross Amount Accumulated Amortization Net ($ in millions) Customers, customer contracts and relationships $ 678.2 $ (336.3) $ 341.9 $ 681.0 $ (312.5) $ 368.5 $ 673.3 $ (285.3) $ 388.0 Trade name — — — — — — 7.0 (6.7) 0.3 Acquired technology 94.5 (71.9) 22.6 95.0 (65.3) 29.7 85.1 (57.7) 27.4 Other 1.8 (0.6) 1.2 1.8 (0.6) 1.2 1.8 (0.6) 1.2 Total intangible assets $ 774.5 $ (408.8) $ 365.7 $ 777.8 $ (378.4) $ 399.4 $ 767.2 $ (350.3) $ 416.9

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Share Table	Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Computation of Net Income (Loss) per Share (In millions, except per share data) Net income (loss) $ 355.8 $ (120.1) $ 599.4 $ (200.1) Basic shares 159.9 157.9 159.2 157.8 Basic net income (loss) per share $ 2.23 $ (0.76) $ 3.77 $ (1.27) Diluted shares: Basic shares 159.9 157.9 159.2 157.8 Stock-based compensation 3.9 — 3.1 — Diluted shares 163.8 157.9 162.3 157.8 Diluted net income (loss) per share $ 2.17 $ (0.76) $ 3.69 $ (1.27)

ENVIRONMENTAL (Tables)

ENVIRONMENTAL (Tables)	6 Months Ended
	Jun. 30, 2021
Environmental Remediation Obligations [Abstract]
Environmental Provisions Charged to Income [Table Text Block]	Environmental provisions charged to income, which are included in costs of goods sold, were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 ($ in millions) Provisions charged to income $ 4.7 $ 2.8 $ 7.2 $ 5.4 Recoveries for costs incurred and expensed — — (2.2) — Environmental expense $ 4.7 $ 2.8 $ 5.0 $ 5.4

SHAREHOLDERS' EQUITY (Tables)

SHAREHOLDERS' EQUITY (Tables)	6 Months Ended
	Jun. 30, 2021
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, 2020 $ (8.4) $ (13.6) $ (781.4) $ (803.4) Unrealized (losses) gains: First quarter (9.0) (35.1) — (44.1) Second quarter 8.2 29.9 — 38.1 Reclassification adjustments of losses into income: First quarter — 11.6 11.9 23.5 Second quarter — 9.3 11.6 20.9 Tax benefit (provision): First quarter — 5.6 (2.7) 2.9 Second quarter — (9.2) (2.6) (11.8) Net change (0.8) 12.1 18.2 29.5 Balance at June 30, 2020 $ (9.2) $ (1.5) $ (763.2) $ (773.9) Balance at January 1, 2021 $ 19.4 $ 21.4 $ (730.7) $ (689.9) Unrealized (losses) gains: First quarter (11.4) 122.0 — 110.6 Second quarter 2.4 41.8 — 44.2 Reclassification adjustments of (gains) losses into income: First quarter — (112.8) 13.7 (99.1) Second quarter — (20.4) 13.7 (6.7) Tax provision: First quarter — (2.2) (3.1) (5.3) Second quarter — (5.1) (3.0) (8.1) Net change (9.0) 23.3 21.3 35.6 Balance at June 30, 2021 $ 10.4 $ 44.7 $ (709.4) $ (654.3)

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Segment Information	Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Sales: ($ in millions) Chlor Alkali Products and Vinyls $ 967.3 $ 651.2 $ 1,834.3 $ 1,411.1 Epoxy 850.0 397.4 1,512.6 874.6 Winchester 404.0 192.6 793.2 380.6 Total sales $ 2,221.3 $ 1,241.2 $ 4,140.1 $ 2,666.3 Income (loss) before taxes: Chlor Alkali Products and Vinyls $ 168.9 $ (57.0) $ 440.0 $ (91.3) Epoxy 165.3 (13.0) 230.5 (1.3) Winchester 109.9 16.0 195.0 26.5 Corporate/other: Environmental expense (4.7) (2.8) (5.0) (5.4) Other corporate and unallocated costs (30.9) (37.4) (63.9) (68.5) Restructuring charges (14.0) (1.7) (20.9) (3.4) Other operating income 0.5 0.1 0.5 0.1 Interest expense (65.9) (69.4) (150.4) (132.5) Interest income — 0.2 0.1 0.3 Non-operating pension income 8.2 4.9 17.5 9.5 Income (loss) before taxes $ 337.3 $ (160.1) $ 643.4 $ (266.0)
Disaggregation of Revenue	Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Sales by geography: ($ in millions) Chlor Alkali Products and Vinyls United States $ 713.6 $ 450.3 $ 1,290.6 $ 984.2 Europe 39.4 26.8 68.9 57.0 Other foreign 214.3 174.1 474.8 369.9 Total Chlor Alkali Products and Vinyls 967.3 651.2 1,834.3 1,411.1 Epoxy United States 253.6 122.5 411.9 281.3 Europe 403.8 140.4 723.8 334.8 Other foreign 192.6 134.5 376.9 258.5 Total Epoxy 850.0 397.4 1,512.6 874.6 Winchester United States 373.6 178.6 738.6 352.7 Europe 6.3 2.3 10.1 4.8 Other foreign 24.1 11.7 44.5 23.1 Total Winchester 404.0 192.6 793.2 380.6 Total United States 1,340.8 751.4 2,441.1 1,618.2 Europe 449.5 169.5 802.8 396.6 Other foreign 431.0 320.3 896.2 651.5 Total sales $ 2,221.3 $ 1,241.2 $ 4,140.1 $ 2,666.3 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Sales by product line: ($ in millions) Chlor Alkali Products and Vinyls Caustic soda $ 400.8 $ 320.2 $ 747.8 $ 680.4 Chlorine, chlorine-derivatives and other co-products 566.5 331.0 1,086.5 730.7 Total Chlor Alkali Products and Vinyls 967.3 651.2 1,834.3 1,411.1 Epoxy Aromatics and allylics 366.5 167.0 678.5 384.4 Epoxy resins 483.5 230.4 834.1 490.2 Total Epoxy 850.0 397.4 1,512.6 874.6 Winchester Commercial 281.5 135.6 542.5 262.7 Military and law enforcement 122.5 57.0 250.7 117.9 Total Winchester 404.0 192.6 793.2 380.6 Total sales $ 2,221.3 $ 1,241.2 $ 4,140.1 $ 2,666.3

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-based compensation expense	Stock-based compensation expense was as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 ($ in millions) Stock-based compensation $ 7.2 $ 4.3 $ 11.9 $ 6.3 Mark-to-market adjustments 6.0 (0.1) 14.1 (3.1) Total expense $ 13.2 $ 4.2 $ 26.0 $ 3.2
Schedule of fair value of stock options granted valuation assumptions	The fair value of each stock 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 weighted-average assumptions: Grant date 2021 Dividend yield 2.76 % Risk-free interest rate 0.94 % Expected volatility of Olin common stock 44 % Expected life (years) 7.0 Weighted-average grant fair value (per option) $ 9.91 Weighted-average exercise price $ 28.99 Options granted 1,094,700
Schedule of fair value of performance share awards granted valuation assumptions	The fair value of each performance stock award based on TSR was estimated on the date of grant, using a Monte Carlo simulation model with the following weighted average assumptions: Grant date 2021 Risk-free interest rate 0.23 % Expected volatility of Olin common stock 55 % Expected average volatility of peer companies 50 % Average correlation coefficient of peer companies 0.50 Expected life (years) 3.0 Grant date fair value (TSR based award) $ 39.96 Grant date fair value (net income based award) $ 28.99 Awards granted 248,700

DEBT (Tables)

DEBT (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Debt	During 2021, activity of our debt outstanding included: Long-term Debt Borrowings (Repayments) Loss on Debt Extinguishment (1) Six Months Ended June 30, 2021 Three Months Ended June 30, 2021 Six Months Ended June 30, 2021 Debt Instrument ($ in millions) Borrowings: Senior Secured Term Loans $ 315.0 Receivables Financing Agreement 50.0 Total borrowings $ 365.0 Repayments: 10.00% senior notes due 2025 $ (500.0) $ 11.3 $ 30.9 9.75% senior notes due 2023 (120.0) — 3.7 5.625% senior notes due 2029 (26.5) 2.9 2.9 5.00% senior notes due 2030 (8.0) 0.6 0.6 Senior Secured Term Loans (150.0) 0.6 0.8 Receivables Financing Agreement (50.0) — — Finance leases (0.7) — — Total repayments $ (855.2) $ 15.4 $ 38.9 Long-term debt repayments, net $ (490.2) (1) Loss on debt extinguishment is included as interest expense in the condensed statements of operations. The loss includes the payment of bond redemption premiums of $12.3 million and $31.0 million for the three and six months ended June 30, 2021, respectively, as well as the write-off of deferred debt issuance costs and recognition of deferred fair value interest rate swap losses of $3.1 million and $7.9 million for the three and six months ended June 30, 2021, respectively, associated with the optional prepayment of existing debt. The cash payments related to the early redemption premiums for the debt extinguishments are classified as cash outflows from financing activities on the condensed statement of cash flows for the six months ended June 30, 2021. The condensed statement of cash flows reflects a correction to the loss on debt extinguishment and early redemption premiums from the previously issued condensed statement of cash flows for the three months ended March 31, 2021, which increased cash flows from net operating activities and decreased cash flows from net financing activities by $18.7 million. During the fourth quarter of 2021, the previously issued statement of cash flows for the year ended December 31, 2020 will reflect the correction of previously presented early redemption premiums, which will increase cash flows from net operating activities and decrease cash flows from net financing activities by $14.6 million.

PENSION PLANS AND RETIREMENT _2

PENSION PLANS AND RETIREMENT BENEFITS (Tables)	6 Months Ended
	Jun. 30, 2021
Retirement Benefits [Abstract]
Components of Net Periodic Benefit (Income) Cost	Pension Benefits Other Postretirement Benefits Three Months Ended June 30, Three Months Ended June 30, 2021 2020 2021 2020 Components of Net Periodic Benefit (Income) Cost ($ in millions) Service cost $ 2.8 $ 2.7 $ 0.3 $ 0.4 Interest cost 12.8 18.8 0.3 0.3 Expected return on plans’ assets (35.0) (35.6) — — Amortization of prior service cost (0.2) — 0.1 — Recognized actuarial loss 13.2 11.1 0.6 0.5 Net periodic benefit (income) cost $ (6.4) $ (3.0) $ 1.3 $ 1.2 Pension Benefits Other Postretirement Benefits Six Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Components of Net Periodic Benefit (Income) Cost ($ in millions) Service cost $ 5.8 $ 5.7 $ 0.7 $ 0.7 Interest cost 25.6 37.5 0.6 0.7 Expected return on plans’ assets (71.1) (71.2) — — Amortization of prior service cost (0.3) — 0.1 — Recognized actuarial loss 26.3 22.3 1.3 1.2 Net periodic benefit (income) cost $ (13.7) $ (5.7) $ 2.7 $ 2.6

INCOME TAXES (Tables)

INCOME TAXES (Tables)	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	The amount of unrecognized tax benefits was as follows: June 30, 2021 2020 ($ in millions) Balance at beginning of year $ 21.3 $ 22.8 Increases for prior year tax positions 20.5 — Decreases for prior year tax positions (3.8) (1.8) Increases for current year tax positions 2.8 1.0 Balance at end of period $ 40.8 $ 22.0
Tax Returns 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 2017 - 2020 U.S. state income tax 2012 - 2020 Canadian federal income tax 2013 - 2020 Brazil 2015 - 2020 Germany 2015 - 2020 China 2014 - 2020 The Netherlands 2015 - 2020

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	6 Months Ended
	Jun. 30, 2021
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: June 30, 2021 December 31, 2020 June 30, 2020 ($ in millions) Natural gas $ 57.3 $ 74.1 $ 59.3 Ethane 44.8 51.8 48.2 Metals 148.7 88.2 117.6 Total notional $ 250.8 $ 214.1 $ 225.1
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 condensed 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: June 30, 2021 December 31, 2020 June 30, 2020 ($ in millions) Asset derivatives: Other current assets Derivatives designated as hedging instruments: Commodity contracts - gains $ 45.5 $ 25.0 $ 5.1 Commodity contracts - losses (1.3) (3.1) (2.8) Derivatives not designated as hedging instruments: Foreign exchange contracts - gains — 2.5 5.3 Foreign exchange contracts - losses — (0.2) (2.9) Total other current assets 44.2 24.2 4.7 Other assets Derivatives designated as hedging instruments: Commodity contracts - gains 14.9 7.4 3.0 Commodity contracts - losses — (0.2) (0.7) Total other assets 14.9 7.2 2.3 Total asset derivatives (1) $ 59.1 $ 31.4 $ 7.0 Liability derivatives: Accrued liabilities Derivatives designated as hedging instruments: Commodity contracts - losses $ 0.7 $ 1.4 $ 8.8 Commodity contracts - gains (0.7) (1.3) (2.4) Derivatives not designated as hedging instruments: Foreign exchange contracts - losses 6.5 — 1.3 Foreign exchange contracts - gains (0.4) — (0.1) Total accrued liabilities 6.1 0.1 7.6 Other liabilities Derivatives designated as hedging instruments: Commodity contracts - losses — 0.8 0.2 Commodity contracts - gains — (0.2) (0.1) Total other liabilities — 0.6 0.1 Total liability derivatives (1) $ 6.1 $ 0.7 $ 7.7 (1) Does not include the impact of cash collateral received from or provided to counterparties.
Summary of effects of derivative instruments on condensed statements of income	The following table summarizes the effects of derivative instruments on our condensed statements of operations: Amount of Gain (Loss) Three Months Ended June 30, Six Months Ended June 30, Location of Gain (Loss) 2021 2020 2021 2020 Derivatives – Cash Flow Hedges ($ in millions) Recognized in other comprehensive loss: Commodity contracts ——— $ 41.8 $ 29.9 $ 163.8 $ (5.2) Reclassified from accumulated other comprehensive loss into income: Commodity contracts Cost of goods sold $ 20.4 $ (9.3) $ 133.2 $ (20.9) Derivatives – Fair Value Hedges Interest rate contracts Interest expense $ (0.6) $ (0.1) $ (1.8) $ (0.2) Derivatives Not Designated as Hedging Instruments Foreign exchange contracts Selling and administration $ (6.2) $ 0.6 $ (8.2) $ 7.1

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Table of financial instruments measured at fair value	The following table summarizes the assets and liabilities measured at fair value in the condensed balance sheets: Fair Value Measurements Balance at June 30, 2021 Level 1 Level 2 Level 3 Total Assets ($ in millions) Commodity contracts $ — $ 59.1 $ — $ 59.1 Total Assets $ — $ 59.1 $ — $ 59.1 Liabilities Foreign exchange contracts $ — $ 6.1 $ — $ 6.1 Total Liabilities $ — $ 6.1 $ — $ 6.1 Balance at December 31, 2020 Assets Commodity contracts $ — $ 29.1 $ — $ 29.1 Foreign exchange contracts — 2.3 — 2.3 Total Assets $ — $ 31.4 $ — $ 31.4 Liabilities Commodity contracts $ — $ 0.7 $ — $ 0.7 Total Liabilities $ — $ 0.7 $ — $ 0.7 Balance at June 30, 2020 Assets Commodity contracts $ — $ 4.6 $ — $ 4.6 Foreign exchange contracts — 2.4 — 2.4 Total Assets $ — $ 7.0 $ — $ 7.0 Liabilities Commodity contracts $ — $ 6.5 $ — $ 6.5 Foreign exchange contracts — 1.2 — 1.2 Total Liabilities $ — $ 7.7 $ — $ 7.7

RESTRUCTURING CHARGES (Details

RESTRUCTURING CHARGES (Details 1) $ in Millions	1 Months Ended	3 Months Ended				4 Months Ended	5 Months Ended	6 Months Ended		19 Months Ended	63 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Mar. 31, 2021USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2021USD ($)	May 18, 2021T	Mar. 15, 2021T	Dec. 11, 2019T	Mar. 21, 2016T
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 14	$ 6.9	$ 1.7	$ 1.7			$ 20.9	$ 3.4		$ 264.3
Inception to date Amounts Utilized (cash)											110.2
Inception to date Amounts Utilized (non-cash)											137.4
Productivity Plan | Corporate/other
Restructuring Cost and Reserve [Line Items]
Restructuring charges		10.1						10.1
Additional restructuring and related expected cost	$ 0	0				$ 0	$ 0	0		$ 0	0
Plaquemine Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Additional restructuring and related expected cost	2	2				2	2	2		2	2
Plaquemine Restructuring Capacity Reduction Percent												20.00%
McIntosh Restructuring Capacity Reduction Tons | T												225,000
McIntosh Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.4				4.8		4.8
Additional restructuring and related expected cost	2	2				2	2	2		2	2
McIntosh Restructuring Capacity Reduction Tons | T													200,000
McIntosh Restructuring Capacity Reduction Percent													50.00%
Freeport 2021 Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		2.8					4.1	4.1
Additional restructuring and related expected cost	25	25				25	25	25		25	25
Freeport 2019 Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.4		0.5				1.2	0.5	63.9
Additional restructuring and related expected cost	45	45				45	45	45		45	45
Freeport Chlor Alkali Capacity Reduction | T														230,000
Chlor Alkali 2016 Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.3		$ 1.2				0.7	$ 2.9		181.4
Additional restructuring and related expected cost	$ 2	$ 2				$ 2	$ 2	$ 2		$ 2	$ 2
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 (Detail_2

RESTRUCTURING CHARGES (Details 2) - USD ($) $ in Millions	3 Months Ended				6 Months Ended		63 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Accrued restructuring costs	$ 16.7		$ 2.6		$ 16.7	$ 2.6	$ 16.7	$ 3.5	$ 3.1
Restructuring charges	14	$ 6.9	1.7	$ 1.7	20.9	3.4	264.3
Amounts utilized					(7.7)	(3.9)
Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Accrued restructuring costs	10.6		0		10.6	0	10.6	1.8	0
Restructuring charges	10.1	0	0	0.1			18.9
Amounts utilized					(1.3)	(0.1)
Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Accrued restructuring costs	6.1		2.6		6.1	2.6	6.1	1.7	3.1
Restructuring charges	0.5	4.6	0	0.1			47.3
Amounts utilized					(0.7)	(0.6)
Facility exit costs
Restructuring Cost and Reserve [Line Items]
Accrued restructuring costs	0		0		0	0	0	$ 0	$ 0
Restructuring charges	$ 3.4	$ 2.3	$ 1.7	$ 1.5			$ 59.4
Amounts utilized					$ (5.7)	$ (3.2)

RESTRUCTURING CHARGES (Detail_3

RESTRUCTURING CHARGES (Details 3) - USD ($) $ in Millions	1 Months Ended	3 Months Ended				4 Months Ended	5 Months Ended	6 Months Ended		19 Months Ended	63 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 14	$ 6.9	$ 1.7	$ 1.7			$ 20.9	$ 3.4		$ 264.3
Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges											137
Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		10.1	0	0	0.1						18.9
Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		3.4	2.3	1.7	1.5						59.4
Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges											1.7
Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.5	$ 4.6	0	$ 0.1						47.3
Plaquemine Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0
Plaquemine Plan | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Plaquemine Plan | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Plaquemine Plan | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Plaquemine Plan | Chlor Alkali Products and Vinyls | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0
Plaquemine Plan | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0
McIntosh Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.4				$ 4.8		4.8
McIntosh Plan | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges						0
McIntosh Plan | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						0
McIntosh Plan | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						0
McIntosh Plan | Chlor Alkali Products and Vinyls | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						0
McIntosh Plan | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges						$ 4.8
Freeport 2021 Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		2.8					$ 4.1	4.1
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges							0
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges							0
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges							4.1
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges							0
Freeport 2021 Plan | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges							$ 0
Freeport 2019 Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.4		0.5				1.2	0.5	$ 63.9
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges										58.9
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges										2.1
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges										2.9
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges										0
Freeport 2019 Plan | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges										$ 0
Chlor Alkali 2016 Plan | Chlor Alkali Products and Vinyls
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.3		$ 1.2				0.7	$ 2.9		181.4
Chlor Alkali 2016 Plan | Chlor Alkali Products and Vinyls | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges											78.1
Chlor Alkali 2016 Plan | Chlor Alkali Products and Vinyls | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges											6.7
Chlor Alkali 2016 Plan | Chlor Alkali Products and Vinyls | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges											52.4
Chlor Alkali 2016 Plan | Chlor Alkali Products and Vinyls | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges											1.7
Chlor Alkali 2016 Plan | Chlor Alkali Products and Vinyls | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges											$ 42.5
Productivity Plan | Corporate/other
Restructuring Cost and Reserve [Line Items]
Restructuring charges		10.1						$ 10.1
Productivity Plan | Corporate/other | Write-off of equipment and facility
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Productivity Plan | Corporate/other | Employee severance and related benefit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		10.1
Productivity Plan | Corporate/other | Facility exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Productivity Plan | Corporate/other | Employee relocation costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0
Productivity Plan | Corporate/other | Lease and other contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 0

ACCOUNTS RECEIVABLES (Details)

ACCOUNTS RECEIVABLES (Details) € in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021EUR (€)	Feb. 24, 2021USD ($)	Dec. 31, 2020USD ($)	Apr. 23, 2020USD ($)	Mar. 27, 2020	Dec. 31, 2019USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables Financing Agreement Outstanding Balance		$ 240.7		$ 240.7			$ 125
AR Facilities, Amount Outstanding to be Serviced	$ 85.7	61.7	$ 85.7	61.7			48.8			$ 63.1
AR Facilities, Gross receivables sold			487.3	457.5
AR Facilities, Payments received from customers on sold accounts			(450.4)	(458.9)
AR Facilities, Interest Expense	0.3	0.4	0.7	1
AR Facilities, Recourse Liability	0	0	0	0			0
Allowance for Doubtful Accounts	12.4	12.5	12.4	12.5			12.3
Other Receivables	72.8	$ 87.7	72.8	$ 87.7			$ 62.4
United States
Accounts, Notes, Loans and Financing Receivable [Line Items]
AR Facilities, Maximum Outstanding Sales	228		228
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
AR Facilities, Maximum Outstanding Sales | €					€ 35.3
Receivables Financing Agreement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables Financing Agreement Maximum Borrowing Capacity								$ 250
Receivables Financing Agreement Minimum Borrowing Percentage									50.00%
Receivables Financing Agreement Collateral	457.9		457.9
Receivables Financing Agreement Outstanding Balance	125		125
Receivables Financing Agreement Available Borrowing Capacity	$ 125		$ 125
$1,615.0 million Senior Secured Credit Facility
Accounts, Notes, Loans and Financing Receivable [Line Items]
2021 Senior Secured Credit Facility						$ 1,615

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Inventory Disclosure [Abstract]
Supplies	$ 115	$ 113.8	$ 111.6
Raw materials	145.1	116.3	64.6
Work in process	145.1	133.2	94
Finished goods	420.9	359.6	392.7
Inventories excluding LIFO reserve	826.1	722.9	662.9
LIFO reserve	(89.6)	(48.2)	(43.8)
Inventories, net	$ 736.5	$ 674.7	$ 619.1

OTHER ASSETS (Details)

OTHER ASSETS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Other Assets [Abstract]
Supply contracts	$ 1,091	$ 1,137.9	$ 1,091	$ 1,137.9	$ 1,122.9
Other	74.9	41.8	74.9	41.8	68.4
Other assets	1,165.9	1,179.7	1,165.9	1,179.7	$ 1,191.3
2020 Supply Contract Payment				461
2020 Supply Contract Payment Accretion Expense				4
Payments under other long-term supply contracts			0	75.8
Amortization of Supply Contracts	$ 17.3	$ 11	$ 34.8	$ 33.3

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS (Details 1) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 1,420.2	$ 2,119.7	$ 1,420.2	$ 2,119.7
Foreign currency translation adjustment	0	0
Goodwill, Accumulated Impairment Loss	699.8
Chlor Alkali Products and Vinyls
Goodwill [Line Items]
Goodwill	1,275.3	1,832.7	1,275.3	1,832.7
Foreign currency translation adjustment	0	0
Goodwill, Accumulated Impairment Loss	557.6
Epoxy
Goodwill [Line Items]
Goodwill	144.9	287	$ 144.9	$ 287
Foreign currency translation adjustment	0	$ 0
Goodwill, Accumulated Impairment Loss	$ 142.2

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS (Details 2) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	$ 774.5	$ 777.8	$ 767.2
Finite-Lived Intangible Assets, Accumulated Amortization	(408.8)	(378.4)	(350.3)
Finite-Lived Intangible Assets, Net	365.7	399.4	416.9
Customers, customer contracts and relationships
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	678.2	681	673.3
Finite-Lived Intangible Assets, Accumulated Amortization	(336.3)	(312.5)	(285.3)
Finite-Lived Intangible Assets, Net	341.9	368.5	388
Trade name
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	0	0	7
Finite-Lived Intangible Assets, Accumulated Amortization	0	0	(6.7)
Finite-Lived Intangible Assets, Net	0	0	0.3
Acquired technology
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	94.5	95	85.1
Finite-Lived Intangible Assets, Accumulated Amortization	(71.9)	(65.3)	(57.7)
Finite-Lived Intangible Assets, Net	22.6	29.7	27.4
Other
Schedule Of Finite Lived And Indefinite Lived Intangible Assets By Major Class [Line Items]
Finite-Lived Intangible Assets, Gross	1.8	1.8	1.8
Finite-Lived Intangible Assets, Accumulated Amortization	(0.6)	(0.6)	(0.6)
Finite-Lived Intangible Assets, Net	$ 1.2	$ 1.2	$ 1.2

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net income (loss)	$ 355.8	$ (120.1)	$ 599.4	$ (200.1)
Basic shares	159,900	157,900	159,200	157,800
Basic net income (loss) per share	$ 2.23	$ (0.76)	$ 3.77	$ (1.27)
Earnings Per Share, Diluted [Abstract]
Basic shares	159,900	157,900	159,200	157,800
Stock-based compensation	3,900	0	3,100	0
Diluted shares	163,800	157,900	162,300	157,800
Diluted net income (loss) per share	$ 2.17	$ (0.76)	$ 3.69	$ (1.27)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Shares	100	10,300	1,100	10,300

ENVIRONMENTAL (Details)

ENVIRONMENTAL (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Environmental Remediation Obligations [Abstract]
Provisions charged to income	$ 4.7	$ 2.8	$ 7.2	$ 5.4
Recoveries for costs incurred and expensed	0	0	(2.2)	0
Environmental expense	4.7	2.8	5	5.4
Reserves for future environmental expenditures - total	148.4	138.6	148.4	138.6	$ 147.2
Reserves for future environmental expenditures - noncurrent	$ 129.4	$ 121.6	$ 129.4	$ 121.6	$ 128.2

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Legal action accrued liabilities	$ 12.9	$ 13.5	$ 12.4

SHAREHOLDERS' EQUITY (Details)

SHAREHOLDERS' EQUITY (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended				6 Months Ended		38 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Apr. 26, 2018
Equity, Class of Treasury Stock [Line Items]
Stock options exercised, Shares					2,400	100
Stock options exercised, Value					$ 50.2	$ 0.5
Foreign Currency Translation Adjustment (net of taxes)
Beginning balance		$ 19.4		$ (8.4)	19.4	(8.4)
Unrealized (losses) gains	$ 2.4	(11.4)	$ 8.2	(9)
Reclassification adjustments of losses (gains) into income	0	0	0	0
Tax benefit (provision)	0	0	0	0
Net change					(9)	(0.8)
Ending Balance	10.4		(9.2)		10.4	(9.2)	$ 10.4
Unrealized (Losses) Gains on Derivative Contracts (net of taxes)
Beginning balance		21.4		(13.6)	21.4	(13.6)
Unrealized (losses) gains	41.8	122	29.9	(35.1)
Reclassification adjustments of losses (gains) into income	(20.4)	(112.8)	9.3	11.6
Tax benefit (provision)	(5.1)	(2.2)	(9.2)	5.6
Net change	16.3		30		23.3	12.1
Ending balance	44.7		(1.5)		44.7	(1.5)	44.7
Pension and Other Postretirement Benefits (net of taxes)
Beginning balance		(730.7)		(781.4)	(730.7)	(781.4)
Unrealized (losses) gains	0	0	0	0
Reclassification adjustments of losses (gains) into income	13.7	13.7	11.6	11.9
Tax benefit (provision)	(3)	(3.1)	(2.6)	(2.7)
Net change					21.3	18.2
Ending balance	(709.4)		(763.2)		(709.4)	(763.2)	(709.4)
Accumulated Other Comprehensive Loss
Beginning balance		(689.9)		(803.4)	(689.9)	(803.4)
Unrealized (losses) gains	44.2	110.6	38.1	(44.1)
Reclassification adjustments of losses (gains) into income	(6.7)	(99.1)	20.9	23.5
Tax benefit (provision)	(8.1)	$ (5.3)	(11.8)	$ 2.9
Net change					35.6	29.5
Ending balance	(654.3)		$ (773.9)		(654.3)	$ (773.9)	(654.3)
Common Stock | 2018 Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Authorized share repurchase program (in dollars)								$ 500
Cost of common stock repurchased and retired (in dollars)							195.9
Remaining authorized repurchase amount (in dollars)	$ 304.1				$ 304.1		$ 304.1
Stock Repurchased and Retired During Period, Shares	0		0		0	0	10,100

SEGMENT INFORMATION (Details 1)

SEGMENT INFORMATION (Details 1) - USD ($) $ in Millions	3 Months Ended				6 Months Ended		63 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021
Sales [Abstract]
Sales	$ 2,221.3		$ 1,241.2		$ 4,140.1	$ 2,666.3
Income (loss) before taxes:
Income (loss) before taxes	337.3		(160.1)		643.4	(266)
Corporate/Other:
Environmental expense	4.7		2.8		7.2	5.4
Restructuring charges	(14)	$ (6.9)	(1.7)	$ (1.7)	(20.9)	(3.4)	$ (264.3)
Other operating income	0.5		0.1		0.5	0.1
Interest expense	(65.9)		(69.4)		(150.4)	(132.5)
Interest income	0		0.2		0.1	0.3
Non-operating pension income	8.2		4.9		17.5	9.5
Corporate/other
Corporate/Other:
Environmental expense	4.7		2.8		5	5.4
Other corporate and unallocated costs	(30.9)		(37.4)		(63.9)	(68.5)
Restructuring charges	(14)		(1.7)		(20.9)	(3.4)
Chlor Alkali Products and Vinyls
Sales [Abstract]
Sales	967.3		651.2		1,834.3	1,411.1
Income (loss) before taxes:
Income (loss) before taxes	168.9		(57)		440	(91.3)
Epoxy
Sales [Abstract]
Sales	850		397.4		1,512.6	874.6
Income (loss) before taxes:
Income (loss) before taxes	165.3		(13)		230.5	(1.3)
Winchester
Sales [Abstract]
Sales	404		192.6		793.2	380.6
Income (loss) before taxes:
Income (loss) before taxes	$ 109.9		$ 16		$ 195	$ 26.5

SEGMENT INFORMATION (Details 2)

SEGMENT INFORMATION (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Sales	$ 2,221.3	$ 1,241.2	$ 4,140.1	$ 2,666.3
United States
Disaggregation of Revenue [Line Items]
Sales	1,340.8	751.4	2,441.1	1,618.2
Europe
Disaggregation of Revenue [Line Items]
Sales	449.5	169.5	802.8	396.6
Other foreign
Disaggregation of Revenue [Line Items]
Sales	431	320.3	896.2	651.5
Chlor Alkali Products and Vinyls
Disaggregation of Revenue [Line Items]
Sales	967.3	651.2	1,834.3	1,411.1
Chlor Alkali Products and Vinyls | United States
Disaggregation of Revenue [Line Items]
Sales	713.6	450.3	1,290.6	984.2
Chlor Alkali Products and Vinyls | Europe
Disaggregation of Revenue [Line Items]
Sales	39.4	26.8	68.9	57
Chlor Alkali Products and Vinyls | Other foreign
Disaggregation of Revenue [Line Items]
Sales	214.3	174.1	474.8	369.9
Epoxy
Disaggregation of Revenue [Line Items]
Sales	850	397.4	1,512.6	874.6
Epoxy | United States
Disaggregation of Revenue [Line Items]
Sales	253.6	122.5	411.9	281.3
Epoxy | Europe
Disaggregation of Revenue [Line Items]
Sales	403.8	140.4	723.8	334.8
Epoxy | Other foreign
Disaggregation of Revenue [Line Items]
Sales	192.6	134.5	376.9	258.5
Winchester
Disaggregation of Revenue [Line Items]
Sales	404	192.6	793.2	380.6
Winchester | United States
Disaggregation of Revenue [Line Items]
Sales	373.6	178.6	738.6	352.7
Winchester | Europe
Disaggregation of Revenue [Line Items]
Sales	6.3	2.3	10.1	4.8
Winchester | Other foreign
Disaggregation of Revenue [Line Items]
Sales	$ 24.1	$ 11.7	$ 44.5	$ 23.1

SEGMENT INFORMATION (Details 3)

SEGMENT INFORMATION (Details 3) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Sales	$ 2,221.3	$ 1,241.2	$ 4,140.1	$ 2,666.3
Chlor Alkali Products and Vinyls
Disaggregation of Revenue [Line Items]
Sales	967.3	651.2	1,834.3	1,411.1
Chlor Alkali Products and Vinyls | Caustic soda
Disaggregation of Revenue [Line Items]
Sales	400.8	320.2	747.8	680.4
Chlor Alkali Products and Vinyls | Chlorine, chlorine-derivatives and other co-products
Disaggregation of Revenue [Line Items]
Sales	566.5	331	1,086.5	730.7
Epoxy
Disaggregation of Revenue [Line Items]
Sales	850	397.4	1,512.6	874.6
Epoxy | Aromatics and allylics
Disaggregation of Revenue [Line Items]
Sales	366.5	167	678.5	384.4
Epoxy | Epoxy resins
Disaggregation of Revenue [Line Items]
Sales	483.5	230.4	834.1	490.2
Winchester
Disaggregation of Revenue [Line Items]
Sales	404	192.6	793.2	380.6
Winchester | Commercial
Disaggregation of Revenue [Line Items]
Sales	281.5	135.6	542.5	262.7
Winchester | Military and law enforcement
Disaggregation of Revenue [Line Items]
Sales	$ 122.5	$ 57	$ 250.7	$ 117.9

STOCK-BASED COMPENSATION (Detai

STOCK-BASED COMPENSATION (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Stock-based compensation	$ 7.2	$ 4.3	$ 11.9	$ 6.3
Mark-to-market adjustments	6	(0.1)	14.1	(3.1)
Total expense	$ 13.2	$ 4.2	$ 26	$ 3.2

STOCK-BASED COMPENSATION (Det_2

STOCK-BASED COMPENSATION (Details 2)	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance Share Award, Total Shareholder Return Percent	50.00%
Performance Share Award Cycle	3
Performance Share Award, Net Income Percent	50.00%
Black-Sholes Option-Pricing Model
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	2.76%
Risk-free interest rate	0.94%
Expected volatility of Olin common stock	44.00%
Expected life (years)	7 years
Weighted-average grant fair value (per option) | $ / shares	$ 9.91
Weighted-average exercise price | $ / shares	$ 28.99
Options granted | shares	1,094,700
Monte Carlo Simulation Model
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.23%
Expected volatility of Olin common stock	55.00%
Expected life (years)	3 years
Expected average volatility of peer companies	0.50
Average correlation coefficient of peer companies	0.50
Grant date fair value (TSR based award) | $	$ 39.96
Grant date fair value (net income based award) | $	$ 28.99
Awards granted | shares	248,700

DEBT (Details 1)

DEBT (Details 1) - USD ($) $ in Millions	Mar. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Feb. 24, 2021	May 08, 2020
Debt Instrument [Line Items]
Long-term Debt Borrowings				$ 365	$ 1,163.2
Long-term Debt Repayments				(855.2)	(425.8)
Long-term debt repayments, net				(490.2)
Loss on debt extinguishment		$ 15.4		38.9	0
Debt early redemption premiums		(12.3)		(31)	0
Write-off of Deferred Debt Issuance Costs and Deferred Fair Value Interest Rate Swap Losses		3.1		$ 7.9
Prior Period Reclassification Adjustment, Cash Flow, Debt Early Redemption Premiums			$ 18.7			$ 14.6
Quarterly Required Principal Payment Percent Through 2022				1.25%
Quarterly Required Principal Payment Percent In 2023				1.875%
Quarterly Required Principal Payment Percent After 2023				2.50%
Long-Term Debt, Maturity, Remainder of Fiscal Year		0.6		$ 0.6
Long-Term Debt, Maturity, Fiscal Year 2022		326.1		326.1
Long-Term Debt, Maturity, Fiscal Year 2023		1		1
Long-Term Debt, Maturity, Fiscal Year 2024		735.8		735.8
Long-Term Debt, Maturity, Fiscal Year 2025		503.1		503.1
Long-Term Debt, Maturity, After Fiscal Year 2025		1,848.5		1,848.5
Payment of Debt Issuance Costs				3.1	$ 9.6
Debt Covenant, Secured Debt Exclusion		250		250
Senior Secured Term Loans
Debt Instrument [Line Items]
Long-term Debt Borrowings				315
Long-term Debt Repayments				(150)
Loss on debt extinguishment		0.6		0.8
Senior Secured Term Loan, Quarterly Installment Repayment				10.2
Debt Covenant, Secured Debt		665		665
Receivables Financing Agreement
Debt Instrument [Line Items]
Long-term Debt Borrowings				50
Long-term Debt Repayments				(50)
Loss on debt extinguishment		0		0
10.00% Senior Notes Due 2025
Debt Instrument [Line Items]
Long-term Debt Repayments				(500)
Loss on debt extinguishment		11.3		30.9
Debt Instrument, Interest Rate, Stated Percentage			10.00%
9.75% Senior Notes Due 2023
Debt Instrument [Line Items]
Long-term Debt Repayments				(120)
Loss on debt extinguishment		0		3.7
5.625% Senior Notes Due 2029
Debt Instrument [Line Items]
Long-term Debt Repayments				(26.5)
Loss on debt extinguishment		2.9		2.9
5.00% Senior Notes Due 2030
Debt Instrument [Line Items]
Long-term Debt Repayments				(8)
Loss on debt extinguishment		0.6		0.6
Finance Leases
Debt Instrument [Line Items]
Long-term Debt Repayments				(0.7)
Loss on debt extinguishment		0		0
$1,615.0 million Senior Secured Credit Facility
Debt Instrument [Line Items]
2021 Senior Secured Credit Facility							$ 1,615
1,300 million Senior Secured Credit Facility
Debt Instrument [Line Items]
2020 Senior Secured Credit Facility								$ 1,300
$315.0 million Senior Secured Delayed Draw Term Loan
Debt Instrument [Line Items]
Senior Secured Delayed-Draw Term Loan, Maximum Borrowing Capacity							315
Proceeds from Issuance of Debt	$ 315
$500.0 million Senior Secured Term Loan
Debt Instrument [Line Items]
Senior Secured Term Loan Facility							500
$800.0 million Senior Secured Revolving Credit Facility
Debt Instrument [Line Items]
Senior Secured Revolving Credit Facility, Maximum Borrowing Capacity							800
Letter of Credit Subfacility, Maximum							$ 100
Senior Secured Revolving Credit Facility, Remaining Borrowing Capacity		799.6		799.6
Letters of Credit Outstanding, Amount		0.4		0.4
Recovery and Go Zone Bonds
Debt Instrument [Line Items]
Debt Covenant, Secured Debt		$ 153		$ 153

CONTRIBUTING EMPLOYEE OWNERSH_2

CONTRIBUTING EMPLOYEE OWNERSHIP PLAN (Details) - USD ($) $ in Millions	Jan. 01, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan Employer Contribution of Eligible Compensation		$ 8.6	$ 6.8	$ 17.3	$ 15
Employer matching contributions to employee ownership plan		$ 3.7	$ 0.7	$ 6.9	$ 1.5
Employer contributions to employee ownership plan						$ 0
Minimum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation		5.00%		5.00%
Maximum
Defined Contribution Plan Disclosure [Line Items]
Contribution To Individual Retirement Account Percentage Of Employees Eligible Compensation		7.50%		7.50%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	3.00%

PENSION PLANS AND RETIREMENT _3

PENSION PLANS AND RETIREMENT BENEFITS (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 2.8	$ 2.7	$ 5.8	$ 5.7
Interest cost	12.8	18.8	25.6	37.5
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(35)	(35.6)	(71.1)	(71.2)
Amortization of prior service cost	(0.2)	0	(0.3)	0
Recognized actuarial loss	13.2	11.1	26.3	22.3
Net periodic benefit (income) cost	(6.4)	(3)	(13.7)	(5.7)
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0.3	0.4	0.7	0.7
Interest cost	0.3	0.3	0.6	0.7
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	0	0	0	0
Amortization of prior service cost	0.1	0	0.1	0
Recognized actuarial loss	0.6	0.5	1.3	1.2
Net periodic benefit (income) cost	$ 1.3	$ 1.2	2.7	2.6
Foreign Plan | Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer			$ 0.6	$ 1.2

PENSION PLANS AND RETIREMENT _4

PENSION PLANS AND RETIREMENT BENEFITS (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Pension Benefits
Service cost	$ 2.8	$ 2.7	$ 5.8	$ 5.7
Interest cost	12.8	18.8	25.6	37.5
Expected return on plans’ assets	(35)	(35.6)	(71.1)	(71.2)
Amortization of prior service cost	(0.2)	0	(0.3)	0
Recognized actuarial loss	13.2	11.1	26.3	22.3
Net periodic benefit (income) cost	(6.4)	(3)	(13.7)	(5.7)
Other Postretirement Benefits
Service cost	0.3	0.4	0.7	0.7
Interest cost	0.3	0.3	0.6	0.7
Expected return on plans’ assets	0	0	0	0
Amortization of prior service cost	0.1	0	0.1	0
Recognized actuarial loss	0.6	0.5	1.3	1.2
Net periodic benefit (income) cost	$ 1.3	$ 1.2	$ 2.7	$ 2.6

INCOME TAXES (Details 1)

INCOME TAXES (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Effective Tax Rate, Discrete Items, net benefit (expense)	$ 93.9		$ 95.2	$ (1)
Effective Tax Rate, Discrete Items, net Percent	22.40%	25.00%	21.60%	25.20%
Statutory Federal Tax Rate	21.00%	21.00%	21.00%	21.00%
Valuation Allowance, Release	$ 103.8
Impact on the effective tax rate, if recognized	40.6	$ 21.8	$ 40.6	$ 21.8
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of year			21.3	22.8
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions			20.5	0
Decreases for prior year tax positions			(3.8)	(1.8)
Increases for current year tax positions			2.8	1
Balance at end of period	40.8	$ 22	40.8	$ 22
Prior Year Tax Position, IRS Audit Resolution	3.8
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	$ 15.6		$ 15.6

INCOME TAXES (Details 2)

INCOME TAXES (Details 2)	6 Months Ended
	Jun. 30, 2021
United States | Internal Revenue Service (IRS) | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2017
United States | Internal Revenue Service (IRS) | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2020
United States | State and Local Jurisdiction | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2012
United States | State and Local Jurisdiction | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2020
Canada | Foreign Country | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2013
Canada | Foreign Country | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2020
Brazil | Foreign Country | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2015
Brazil | Foreign Country | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2020
Germany | Foreign Country | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2015
Germany | Foreign Country | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2020
China | Foreign Country | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2014
China | Foreign Country | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2020
The Netherlands | Foreign Country | Minimum
Income Tax Examination [Line Items]
Open Tax Year	2015
The Netherlands | Foreign Country | Maximum
Income Tax Examination [Line Items]
Open Tax Year	2020

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS (Details Textuals) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Aug. 31, 2019	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Derivative [Line Items]
Notional amount		$ 250.8	$ 214.1	$ 225.1
Forward Contracts
Derivative [Line Items]
Notional amount		270.8	169.9	176.6
Forward Contracts Sell
Derivative [Line Items]
Notional amount		99.7	$ 113.6	$ 111.7
Commodity Contract
Derivative [Line Items]
Cash Flow Hedges Derivative Instruments at Fair Value, Net		59
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months		$ 33.6
Interest Rate Swaps Designated As Fair Value Hedges
Derivative [Line Items]
August Interest Rate Swap Settlement	$ 2.3

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS (Details 1) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Derivative [Line Items]
Notional amount	$ 250.8	$ 214.1	$ 225.1
Forward Contracts
Derivative [Line Items]
Notional amount	270.8	169.9	176.6
Forward Contracts Sell
Derivative [Line Items]
Notional amount	99.7	113.6	111.7
Natural Gas Commodity Forward Contracts
Derivative [Line Items]
Notional amount	57.3	74.1	59.3
Ethane Commodity Forward Contracts
Derivative [Line Items]
Notional amount	44.8	51.8	48.2
Metals Commodity Forward Contracts
Derivative [Line Items]
Notional amount	$ 148.7	$ 88.2	$ 117.6

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS (Details 2) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Derivatives, Fair Value [Line Items]
Asset derivatives	$ (59.1)	$ (31.4)	$ (7)
Liability derivatives	(6.1)	(0.7)	(7.7)
Other Current Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	(44.2)	(24.2)	(4.7)
Other Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	(14.9)	(7.2)	(2.3)
Accrued Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	(6.1)	(0.1)	(7.6)
Other Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	0	(0.6)	(0.1)
Commodity Contracts Gains | Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	(45.5)	(25)	(5.1)
Commodity Contracts Gains | Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	(14.9)	(7.4)	(3)
Commodity Contracts Gains | Designated as Hedging Instrument | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	0.7	1.3	2.4
Commodity Contracts Gains | Designated as Hedging Instrument | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	0	0.2	0.1
Commodity Contracts Losses | Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	1.3	3.1	2.8
Commodity Contracts Losses | Designated as Hedging Instrument | Other Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	0	0.2	0.7
Commodity Contracts Losses | Designated as Hedging Instrument | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	(0.7)	(1.4)	(8.8)
Commodity Contracts Losses | Designated as Hedging Instrument | Other Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	0	(0.8)	(0.2)
Foreign Exchange Contract | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	0	(2.5)	(5.3)
Foreign Exchange Contract | Not Designated as Hedging Instrument | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	0.4	0	0.1
Foreign Exchange Contract Loss | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Asset derivatives	0	0.2	2.9
Foreign Exchange Contract Loss | Not Designated as Hedging Instrument | Accrued Liabilities
Derivatives, Fair Value [Line Items]
Liability derivatives	$ (6.5)	$ 0	$ (1.3)

DERIVATIVE FINANCIAL INSTRUME_6

DERIVATIVE FINANCIAL INSTRUMENTS (Details 3) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in other comprehensive loss:	$ 41.8	$ 122	$ 29.9	$ (35.1)
Commodity Contract | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in other comprehensive loss:	41.8		29.9		$ 163.8	$ (5.2)
Commodity Contract | Cost of goods sold | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Reclassified from accumulated other comprehensive loss into income:	20.4		(9.3)		133.2	(20.9)
Interest Rate Swap | Interest expense | Fair Value Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss)	(0.6)		(0.1)		(1.8)	(0.2)
Foreign Exchange Contract | Selling and administration | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss)	$ (6.2)		$ 0.6		$ (8.2)	$ 7.1

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details Textuals) - Nonrecurring - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 0	$ 0	$ 0
Liabilities, Fair Value Disclosure	$ 0	$ 0	$ 0

FAIR VALUE MEASUREMENTS (Deta_2

FAIR VALUE MEASUREMENTS (Details 1) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	$ 59.1	$ 31.4	$ 7
Derivative Liability	6.1	0.7	7.7
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0	0
Derivative Liability	0	0	0
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	59.1	31.4	7
Derivative Liability	6.1	0.7	7.7
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0	0
Derivative Liability	0	0	0
Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	59.1	29.1	4.6
Derivative Liability		0.7	6.5
Commodity Contract | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0	0
Derivative Liability		0	0
Commodity Contract | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	59.1	29.1	4.6
Derivative Liability		0.7	6.5
Commodity Contract | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0	0
Derivative Liability		0	0
Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		2.3	2.4
Derivative Liability	6.1		1.2
Foreign Exchange Contract | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		0	0
Derivative Liability	0		0
Foreign Exchange Contract | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		2.3	2.4
Derivative Liability	6.1		1.2
Foreign Exchange Contract | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset		$ 0	0
Derivative Liability	$ 0		$ 0

FAIR VALUE MEASUREMENTS (Deta_3

FAIR VALUE MEASUREMENTS (Details 2) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Fair Value, Inputs, Level 2
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Long-term Debt, Fair Value	$ 3,669.2	$ 4,177.2	$ 4,056.7