Trinseo (TSE) 10-Q 5 May 23 2023 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2023	Apr. 28, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	001-36473
Entity Registrant Name	Trinseo PLC
Entity Incorporation, State or Country Code	L2
Entity Tax Identification Number	00-0000000
Entity Address, Address Line One	440 East Swedesford Road
Entity Address, Address Line Two	Suite 301
Entity Address, City or Town	Wayne
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19087
City Area Code	610
Local Phone Number	240-3200
Title of 12(b) Security	Ordinary Shares, par value $0.01 per share
Trading Symbol	TSE
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		35,146,342
Entity Central Index Key	0001519061
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 217.1	$ 211.7
Accounts receivable, net of allowance for doubtful accounts (March 31, 2023: $6.9; December 31, 2022: $7.3)	622.5	586
Inventories	502.6	553.6
Other current assets	34.1	39.4
Total current assets	1,376.3	1,390.7
Investments in unconsolidated affiliates	252.7	255.1
Property, plant and equipment, net of accumulated depreciation (March 31, 2023: $708.4; December 31, 2022: $668.8)	681	691.1
Other assets
Goodwill	414.2	410.4
Other intangible assets, net	759.4	772
Right-of-use assets - operating, net	73	76.1
Deferred income tax assets	114.2	97.3
Deferred charges and other assets	70.7	67.5
Total other assets	1,431.5	1,423.3
Total assets	3,741.5	3,760.2
Current liabilities
Short-term borrowings and current portion of long-term debt	16.6	16
Accounts payable	454.6	438.1
Current lease liabilities - operating	16.7	17.1
Income taxes payable	2.7	9.9
Accrued expenses and other current liabilities	227.2	208.3
Total current liabilities	717.8	689.4
Noncurrent liabilities
Long-term debt, net of unamortized deferred financing fees	2,299.9	2,301.6
Noncurrent lease liabilities - operating	57.2	60.2
Deferred income tax liabilities	53.7	59.8
Other noncurrent obligations	236.7	228.9
Total noncurrent liabilities	2,647.5	2,650.5
Commitments and contingencies (Note 13)
Shareholders' equity
Ordinary shares, $0.01 nominal value, 4,000.0 shares authorized (March 31, 2023: 39.3 shares issued and 35.2 shares outstanding; December 31, 2022: 39.2 shares issued and 35.1 shares outstanding)	0.4	0.4
Preferred shares, €0.01 nominal value, 1,000.0 shares authorized (no shares issued or outstanding)
Additional paid-in-capital	493.3	486.7
Treasury shares, at cost (March 31, 2023: 4.1 shares; December 31, 2022: 4.1 shares)	(200)	(200)
Retained earnings	210.4	264.5
Accumulated other comprehensive loss	(127.9)	(131.3)
Total shareholders' equity	376.2	420.3
Total liabilities and shareholders' equity	$ 3,741.5	$ 3,760.2

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) shares in Thousands, $ in Millions	Mar. 31, 2023 USD ($) $ / shares shares	Mar. 31, 2023 € / shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2022 € / shares
Allowance for doubtful accounts | $	$ 6.9		$ 7.3
Accumulated depreciation | $	$ 708.4		$ 668.8
Ordinary shares, nominal value | $ / shares	$ 0.01		$ 0.01
Ordinary shares, shares authorized	4,000,000		4,000,000
Ordinary shares, shares issued	39,300		39,200
Ordinary shares, shares outstanding	35,200		35,100
Treasury stock, shares	4,100		4,100
Preferred stock, par value | € / shares		€ 0.01		€ 0.01
Preferred stock, shares authorized	1,000,000		1,000,000
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Deferred Ordinary Shares
Ordinary shares, nominal value | € / shares		€ 1		€ 1
Ordinary shares, shares authorized	25		25
Ordinary shares, shares issued	25		25
Ordinary shares, shares outstanding	25		25

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Consolidated Statements of Operations
Net sales	$ 996.3	$ 1,386.7
Cost of sales	959.1	1,210.7
Gross profit	37.2	176
Selling, general and administrative expenses	84.7	96.7
Equity in earnings of unconsolidated affiliates	17.6	21.6
Impairment and other charges	0.3	36.3
Operating income (loss)	(30.2)	64.6
Interest expense, net	38.3	21.9
Other expense (income), net	(2.9)	3
Income (loss) from continuing operations before income taxes	(65.6)	39.7
Provision for (benefit from) income taxes	(16.7)	22.6
Net income (loss) from continuing operations	(48.9)	17.1
Net loss from discontinued operations, net of income taxes		(0.4)
Net income (loss)	$ (48.9)	$ 16.7
Earnings Per Share
Weighted average shares- basic	35	37.3
Net income (loss) per share- basic: continuing operations	$ (1.40)	$ 0.46
Net income (loss) per share- basic: discontinued operations		(0.01)
Net income (loss) per share- basic	$ (1.40)	$ 0.45
Weighted average shares- diluted	35	38.1
Net income (loss) per share- diluted: continuing operations	$ (1.40)	$ 0.45
Net income (loss) per share- diluted: discontinued operations		(0.01)
Net income (loss) per share- diluted	$ (1.40)	$ 0.44

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Consolidated Statements of Comprehensive Income (Loss)
Net income (loss)	$ (48.9)	$ 16.7
Other comprehensive income (loss), net of tax:
Cumulative translation adjustments (net of tax of $0.0 and $0.0)	10.5	(4.3)
Net gain (loss) on cash flow hedges (net of tax (benefit) of $(2.5) and $0.0)	(7.4)	1.5
Amounts reclassified from accumulated other comprehensive income	0.3	0.3
Total other comprehensive income (loss), net of tax	3.4	(2.5)
Comprehensive income (loss)	$ (45.5)	$ 14.2

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Consolidated Statements of Comprehensive Income (Loss)
Cumulative translation adjustments, tax	$ 0	$ 0
Net gain (loss) on cash flow hedges, tax	$ (2.5)	$ 0

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders Equity - USD ($) shares in Millions, $ in Millions	Common Stock	Additional Paid-In Capital	Treasury Shares	Accumulated other comprehensive income(Loss)	Retained Earnings	Total
Balance at beginning of period at Dec. 31, 2021	$ 0.4	$ 468.1	$ (50)	$ (147.2)	$ 741.8	$ 1,013.1
Balance at beginning of period, shares at Dec. 31, 2021	37.9
Balance at beginning of period, Treasury shares at Dec. 31, 2021			1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)					16.7	16.7
Other comprehensive income				(2.5)		(2.5)
Share-based compensation activity		7.6				7.6
Share-based compensation activity, shares	0.2
Purchase of treasury shares			$ (50)			(50)
Purchase of treasury shares, shares	(0.9)		0.9
Dividends on ordinary shares					(12.1)	(12.1)
Balance at end of period at Mar. 31, 2022	$ 0.4	475.7	$ (100)	(149.7)	746.4	972.8
Balance at end of period, shares at Mar. 31, 2022	37.2
Balance at end of period, Treasury shares at Mar. 31, 2022			1.9
Balance at beginning of period at Dec. 31, 2022	$ 0.4	486.7	$ (200)	(131.3)	264.5	$ 420.3
Balance at beginning of period, shares at Dec. 31, 2022	35.1					35.1
Balance at beginning of period, Treasury shares at Dec. 31, 2022			4.1			4.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)					(48.9)	$ (48.9)
Other comprehensive income				3.4		3.4
Share-based compensation activity		6.6				6.6
Share-based compensation activity, shares	0.1
Dividends on ordinary shares					(5.2)	(5.2)
Balance at end of period at Mar. 31, 2023	$ 0.4	$ 493.3	$ (200)	$ (127.9)	$ 210.4	$ 376.2
Balance at end of period, shares at Mar. 31, 2023	35.2					35.2
Balance at end of period, Treasury shares at Mar. 31, 2023			4.1			4.1

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Shareholders Equity (Parenthetical)) - $ / shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Consolidated Statements of Shareholders' Equity
Dividends on ordinary shares	$ 0.14	$ 0.32

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities
Net income (loss)	$ (48.9)	$ 16.7
Less: Net loss from discontinued operations		(0.4)
Net income (loss) from continuing operations	(48.9)	17.1
Adjustments to reconcile net income (loss) from continuing operations to net cash provided by (used in) operating activities - continuing operations
Depreciation and amortization	56	53
Amortization of deferred financing fees and issuance discount	2.3	2.3
Deferred income tax (benefit)	(16.6)	9
Share-based compensation expense	8.2	8.3
Earnings of unconsolidated affiliates, net of dividends	2.4	(14.1)
Unrealized net (gain) loss on foreign exchange forward contracts	1.5	(2.6)
Unrealized net loss on commodity economic swap contracts	5.8
Gain on sale of businesses and other assets		(0.3)
Impairment charges or write-offs	0.3	0.7
Changes in assets and liabilities
Accounts receivable	(29.2)	(79.8)
Inventories	55.1	(66.2)
Accounts payable and other current liabilities	26.5	42
Income taxes payable	(7)	5.9
Other assets, net	3.8	12.7
Other liabilities, net	(14.8)	6.8
Cash provided by (used in) operating activities - continuing operations	45.4	(5.2)
Cash provided by operating activities - discontinued operations		0.2
Cash provided by (used in) operating activities	45.4	(5)
Cash flows from investing activities
Capital expenditures	(21.8)	(23.9)
Cash paid for asset or business acquisitions, net of cash acquired ($0.0 and $1.0)		(22.2)
Cash used in investing activities - continuing operations	(21.8)	(46.1)
Cash used in investing activities - discontinued operations		(0.9)
Cash used in investing activities	(21.8)	(47)
Cash flows from financing activities
Short-term borrowings, net	(2.7)	(3.6)
Purchase of treasury shares		(51.9)
Dividends paid	(11.8)	(12.4)
Proceeds from exercise of option awards	0.1	1.7
Withholding taxes paid on restricted share units	(1.3)	(0.8)
Acquisition-related contingent consideration payment	(1.2)
Repurchases and repayments of long-term debt	(3.6)	(3.6)
Cash used in financing activities	(20.5)	(70.6)
Effect of exchange rates on cash	2.3	(1.7)
Net change in cash, cash equivalents, and restricted cash	5.4	(124.3)
Cash, cash equivalents, and restricted cash-beginning of period	211.7	573
Cash, cash equivalents, and restricted cash-end of period	217.1	448.7
Cash and cash equivalents-end of period	$ 217.1	$ 448.7

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2023
Basis of Presentation
Basis of Presentation	NOTE 1—BASIS OF PRESENTATION The unaudited interim condensed consolidated financial statements of Trinseo PLC and its subsidiaries (the “Company”) as of and for the periods ended March 31, 2023 and 2022 were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and reflect all adjustments, consisting only of normal recurring adjustments, which, in the opinion of management, are considered necessary for the fair statement of the results for the periods presented. Because they cover interim periods, the statements and related notes to the financial statements do not include all disclosures normally provided in annual financial statements, and therefore, these statements should be read in conjunction with the 2022 audited consolidated financial statements included within the Company’s Annual Report on Form 10-K (“Annual Report”) filed with the Securities and Exchange Commission (“SEC”) on February 27, 2023. The Company’s condensed consolidated financial statements presented herein reflect the latest estimates and assumptions made by management that affect the reported amounts and related disclosures as of and for the period ended March 31, 2023. However, actual results could differ from these estimates and assumptions. The December 31, 2022 condensed consolidated balance sheet data presented herein was derived from the Company’s December 31, 2022 audited consolidated financial statements, but does not include all disclosures required by GAAP for annual periods. Throughout this Quarterly Report, unless otherwise indicated, amounts and activity are presented on a continuing operations basis.

Recent Accounting Guidance

Recent Accounting Guidance	3 Months Ended
	Mar. 31, 2023
Recent Accounting Guidance
Recent Accounting Guidance	NOTE 2—RECENT ACCOUNTING GUIDANCE As of March 31, 2023, there was no recently issued accounting standards which would have a material effect on the Company’s condensed consolidated financial statements.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2023
Acquisitions
Acquisitions	NOTE 3—ACQUISITIONS Acquisition of Heathland B.V. On January 3, 2022, the Company completed the acquisition of Heathland B.V. (“Heathland”) from Heathland Holding B.V. (“Heathland Holding”), through the purchase of all issued and outstanding shares (the “Heathland Acquisition”). Heathland is a leading collector and recycler of post-consumer and post-industrial plastic wastes in Europe. The total purchase price consideration is estimated to be $29.3 million, including an initial cash purchase price of $22.9 million which was paid during the three months ended March 31, 2022, as well as $6.4 million of contingent cash consideration, representing the fair value of certain earn-out payments. The maximum amount of potential earn-out payments is $6.8 million, which will become payable to Heathland Holding as and when the related performance milestones or thresholds are achieved over the three-year period following the date of acquisition. Heathland results are included within the Plastics Solution segment. The Company allocated the purchase price of the acquisition to identifiable assets acquired and liabilities assumed based on their estimated fair values as of the acquisition date. Refer to the Annual Report for further information. In February 2023, the Company delivered the first year earn-out to Heathland Holding based on its first related performance milestones or threshold in the amount of $1.2 million. ​

Divestitures and Discontinued O

Divestitures and Discontinued Operations	3 Months Ended
	Mar. 31, 2023
Divestitures and Discontinued Operations
Divestitures and Discontinued Operations	NOTE 4—DIVESTITURES AND DISCONTINUED OPERATIONS On December 1, 2021, the Company completed the divestiture of its Synthetic Rubber business to Synthos S.A. and certain of its subsidiaries (together, “Synthos”) for a purchase price of $402.4 million, which reflected a reduction of approximately $41.6 million for the assumption of pension liabilities by Synthos and $47.0 million for net working capital (excluding inventory) retained by Trinseo. Refer to the Annual Report for further information. At closing, the Company and Synthos executed a long-term supply agreement, in which Trinseo will supply Synthos certain raw materials used in the Synthetic Rubber business subsequent to the sale. For the three months ended March 31, 2023, the Company recorded $13.5 million in net sales and $15.4 million in cost of sales related to the supply agreement, which is recorded in continuing operations. The results of the Synthetic Rubber business for the three months ended March 31, 2023 was insignificant. The following table summarizes the results of the Synthetic Rubber business for the three months ended March 31, 2022, which are reflected as discontinued operations in the Company’s condensed consolidated statements of operations: ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2022 Net sales $ 0.1 Cost of sales ​ 0.7 ​ Gross loss ​ (0.6) ​ Selling, general and administrative expenses ​ (0.2) ​ Operating loss ​ (0.4) ​ Other expense, net ​ ​ — ​ Loss from discontinued operations before income taxes ​ (0.4) ​ Provision for income taxes ​ — ​ Net loss from discontinued operations ​ $ (0.4) ​ ​

Net Sales

Net Sales	3 Months Ended
	Mar. 31, 2023
Net Sales
Net Sales	NOTE 5—NET SALES Refer to the Annual Report for information on the Company's accounting policies and further background related to its net sales. The following table provides disclosure of net sales to external customers by primary geographical market (based on the location where sales originated), by segment for the three months ended March 31, 2023 and 2022. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Engineered ​ Latex ​ Plastics ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Materials ​ Binders ​ Solutions ​ Polystyrene ​ Feedstocks ​ Total March 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ United States ​ $ 110.9 ​ $ 67.6 ​ $ 68.7 ​ $ — ​ $ 3.6 ​ $ 250.8 ​ Europe ​ 73.5 ​ 128.1 ​ 165.3 ​ 138.5 ​ 39.4 ​ 544.8 ​ Asia-Pacific ​ 18.9 ​ 50.7 ​ 27.8 ​ 70.6 ​ — ​ 168.0 ​ Rest of World ​ 2.9 ​ 1.7 ​ 28.1 ​ — ​ — ​ 32.7 ​ Total ​ $ 206.2 ​ $ 248.1 ​ $ 289.9 ​ $ 209.1 ​ $ 43.0 ​ $ 996.3 ​ March 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ United States ​ $ 138.4 ​ $ 82.2 ​ $ 84.5 ​ $ — ​ $ 3.9 ​ $ 309.0 ​ Europe ​ 118.7 ​ 150.9 ​ 246.6 ​ 214.6 ​ 66.4 ​ 797.2 ​ Asia-Pacific ​ 35.3 ​ 71.7 ​ 37.2 ​ 103.4 ​ — ​ ​ 247.6 ​ Rest of World ​ 2.8 ​ 1.9 ​ 28.2 ​ — ​ — ​ 32.9 ​ Total ​ $ 295.2 ​ $ 306.7 ​ $ 396.5 ​ $ 318.0 ​ $ 70.3 ​ $ 1,386.7 ​ ​

Investments in Unconsolidated A

Investments in Unconsolidated Affiliates	3 Months Ended
	Mar. 31, 2023
Investments in Unconsolidated Affiliates
Investments in Unconsolidated Affiliates	NOTE 6—INVESTMENTS IN UNCONSOLIDATED AFFILIATES The Company is currently supplemented by one joint venture, Americas Styrenics LLC (“Americas Styrenics,” a styrene and polystyrene joint venture with Chevron Phillips Chemical Company LP), which is accounted for using the equity method. The results of Americas Styrenics are included within its own reporting segment. Americas Styrenics is a privately held company; therefore, a quoted market price for its equity interests is not available. The summarized financial information of the Company’s unconsolidated affiliate is shown below. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Sales $ 443.3 $ 524.4 ​ Gross profit ​ $ 52.9 ​ $ 48.1 ​ Net income ​ $ 37.8 ​ $ 36.1 ​ ​ As of March 31, 2023 and December 31, 2022, the Company’s investment in Americas Styrenics was $252.7 million and $255.1 million, respectively, which was $7.0 million and $8.4 million greater than the Company’s 50% share of the underlying net assets of Americas Styrenics, respectively. This amount represents the difference between the book value of assets held by the joint venture and the Company’s 50% share of the total recorded value of the joint venture’s assets, inclusive of certain adjustments to conform with the Company’s accounting policies. This difference is being amortized over a weighted average remaining useful life of approximately 1.8 years as of March 31, 2023. The Company received dividends of $20.0 million and $7.5 million from Americas Styrenics during the three months ended March 31, 2023 and 2022, respectively.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2023
Inventories
Inventories	NOTE 7—INVENTORIES Inventories consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ 2023 ​ 2022 Finished goods $ 195.3 $ 218.4 Raw materials and semi-finished goods ​ 265.9 ​ 295.6 Supplies ​ 41.4 ​ 39.6 Total ​ $ 502.6 ​ $ 553.6 ​

Debt

Debt	3 Months Ended
	Mar. 31, 2023
Debt
Debt	NOTE 8—DEBT Refer to the Annual Report for definitions of capitalized terms not included herein and further background on the Company’s debt structure discussed below. The Company was in compliance with all debt related covenants as of March 31, 2023 and December 31, 2022. As of March 31, 2023 and December 31, 2022, debt consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ December 31, 2022 ​ ​ Interest Rate as of March 31, 2023 Maturity Date Carrying Amount Unamortized Deferred Financing Fees (1) Total Debt, Less Unamortized Deferred Financing Fees Carrying Amount Unamortized Deferred Financing Fees (1) Total Debt, Less Unamortized Deferred Financing Fees ​ Senior Credit Facility ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024 Term Loan B ​ 6.840% ​ September 2024 ​ $ 661.7 ​ $ (4.4) ​ $ 657.3 ​ $ 663.4 ​ $ (5.1) ​ $ 658.3 ​ 2028 Term Loan B ​ 7.340% ​ May 2028 ​ ​ 734.1 ​ ​ (13.8) ​ ​ 720.3 ​ ​ 735.9 ​ ​ (14.4) ​ ​ 721.5 ​ 2026 Revolving Facility (2) ​ Various ​ May 2026 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ 2029 Senior Notes ​ 5.125% ​ April 2029 ​ ​ 447.0 ​ ​ (12.5) ​ ​ 434.5 ​ ​ 447.0 ​ ​ (12.9) ​ ​ 434.1 ​ 2025 Senior Notes ​ 5.375% ​ September 2025 ​ ​ 500.0 ​ ​ (3.4) ​ ​ 496.6 ​ ​ 500.0 ​ ​ (3.7) ​ ​ 496.3 ​ Accounts Receivable Securitization Facility (3) ​ Various ​ November 2024 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Other indebtedness ​ Various ​ Various ​ ​ 7.8 ​ ​ — ​ ​ 7.8 ​ ​ 7.4 ​ ​ — ​ ​ 7.4 ​ Total debt ​ ​ ​ ​ ​ $ 2,350.6 ​ $ (34.1) ​ $ 2,316.5 ​ $ 2,353.7 ​ $ (36.1) ​ $ 2,317.6 ​ Less: current portion (4) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (16.6) ​ ​ ​ ​ ​ ​ ​ ​ (16.0) ​ Total long-term debt, net of unamortized deferred financing fees ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 2,299.9 ​ ​ ​ ​ ​ ​ ​ $ 2,301.6 ​ (1) This caption does not include deferred financing fees related to the Company’s revolving facilities, which are included within “Deferred charges and other assets” on the condensed consolidated balance sheets. (2) As of March 31, 2023, under the 2026 Revolving Facility, the Company had a capacity of $375.0 million and $22.0 million outstanding letters of credit. As of March 31, 2023, the Company had funds available for borrowing of $100.5 million (net of the applicable $12.0 million outstanding letters of credit as defined in the secured credit agreement), which reflects the borrowing limit imposed by the springing covenant. The springing covenant applies when 30% or more of the 2026 Revolving Facility’s capacity is drawn which then requires the Company to meet a first lien net leverage ratio (as defined in the secured credit agreement) not to exceed 3.50 x at the end of each financial quarter. As of March 31, 2023, the first lien net leverage ratio was 4.85 x and the outstanding borrowings did not exceed the 30% threshold. Additionally, the Company is required to pay a quarterly commitment fee in respect of any unused commitments under this facility equal to 0.375% per annum. (3) As of March 31, 2023, this facility had a borrowing capacity of $150.0 million, and the Company had approximately $150.0 million of accounts receivable available to support this facility, based on the pool of eligible accounts receivable. (4) The current portion of long-term debt was primarily related to $14.5 million of the scheduled future principal payments on both the 2024 Term Loan B and 2028 Term Loan B as of March 31, 2023 and December 31, 2022.

Goodwill

Goodwill	3 Months Ended
	Mar. 31, 2023
Goodwill and Intangible assets
Goodwill	NOTE 9—GOODWILL The following table shows changes in the carrying amount of goodwill, by segment, from December 31, 2022 to March 31, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Engineered ​ Latex ​ Plastics ​ ​ ​ ​ ​ Americas ​ ​ ​ ​ Materials Binders Solutions Polystyrene Feedstocks Styrenics Total Balance at December 31, 2022 ​ $ 348.9 ​ $ 14.8 ​ $ 42.5 ​ $ 4.2 ​ $ — ​ $ — ​ $ 410.4 ​ Foreign currency impact ​ 2.6 ​ ​ 0.3 ​ ​ 0.8 ​ ​ 0.1 ​ ​ — ​ ​ — ​ 3.8 ​ Balance at March 31, 2023 ​ $ 351.5 ​ $ 15.1 ​ $ 43.3 ​ $ 4.3 ​ $ — ​ $ — ​ $ 414.2 ​ ​ As a result of the Company’s fourth quarter 2022 impairment testing, an impairment charge was taken for the PMMA business and Aristech Surfaces reporting units primarily due to the continuation of the challenging macroeconomic environment experienced in 2022 into the fourth quarter of 2022, including significantly lower demand for building & construction and wellness applications, which led to lower operating results including slower growth projections, and a prolonged drop in market capitalization, as well as an increase in the weighted average cost of capital. This goodwill may be at risk for future impairment due to the remaining fair value being equal to carrying value as a result of the recorded impairment. While the challenging macroeconomic environment has continued to impact these businesses in the first quarter of 2023, the Company performed qualitative analyses over this goodwill, including consideration of current and estimated future financial results of the related businesses, general and industry-specific economic conditions, changes in reporting unit carrying values and potential changes to the assumptions used in the previous fair value calculations. Based on these analyses, the Company has not identified any triggering events since the fourth quarter of 2022 impairment test indicating that is more likely than not that goodwill is impaired. Should these conditions persist, or other events occur indicating that the estimated future cash flows of these businesses have declined, the Company may be required to record future non-cash impairment charges related to goodwill. As of March 31, 2023 and December 31, 2022, the reported balance of goodwill included accumulated impairment losses of $297.1 million in the Engineered Materials segment.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2023
Derivative Instruments
Derivative Instruments	NOTE 10—DERIVATIVE INSTRUMENTS The Company’s ongoing business operations expose it to various risks, including fluctuating foreign exchange rates, interest rate risk, and commodity price risk, in particular natural gas. To manage these risks, the Company periodically enters into derivative financial instruments, such as foreign exchange forward contracts, interest rate swap agreements, and commodity swaps agreements, forward contracts, or options. The Company does not hold or enter into financial instruments for trading or speculative purposes. All derivatives are recorded on the condensed consolidated balance sheets at fair value. Foreign Exchange Forward Contracts Certain subsidiaries have assets and liabilities denominated in currencies other than their respective functional currencies, which creates foreign exchange risk. The Company’s principal strategy in managing its exposure to changes in foreign currency exchange rates is to naturally hedge the foreign currency-denominated liabilities on its balance sheet against corresponding assets of the same currency, such that any changes in liabilities due to fluctuations in exchange rates are offset by changes in their corresponding foreign currency assets. In order to further reduce this exposure, the Company also uses foreign exchange forward contracts to economically hedge the impact of the variability in exchange rates on assets and liabilities denominated in certain foreign currencies. These derivative contracts are not designated for hedge accounting treatment. As of March 31, 2023, the Company had open foreign exchange forward contracts with a notional U.S. dollar equivalent absolute value of $657.5 million. The following table displays the notional amounts of the most significant net foreign exchange hedge positions outstanding as of March 31, 2023: ​ ​ ​ ​ ​ ​ ​ March 31, Buy / (Sell) 2023 Euro ​ $ (520.9) Chinese Yuan ​ $ (48.4) South Korean Won ​ $ (21.8) Swiss Franc ​ $ (19.6) Swedish Krona ​ $ 14.7 ​ Open foreign exchange forward contracts as of March 31, 2023 had maturities occurring over a period of two months. Foreign Exchange Cash Flow Hedges The Company also enters into forward contracts, as deemed appropriate, with the objective of managing the currency risk associated with forecasted U.S. dollar-denominated raw materials purchases by one of its subsidiaries whose functional currency is the euro. By entering into these forward contracts, which are designated as cash flow hedges, the Company buys a designated amount of U.S. dollars and sells euros at the prevailing market rate to mitigate the risk associated with the fluctuations in the euro-to-U.S. dollar foreign currency exchange rates. The qualifying hedge contracts are marked-to-market at each reporting date and any unrealized gains or losses are included in Accumulated Other Comprehensive Income (“AOCI”) to the extent effective, and reclassified to cost of sales in the period during which the transaction affects earnings or it becomes probable that the forecasted transaction will not occur. The Company had no open foreign exchange cash flow hedges as of Commodity Cash Flow Hedges & Commodity Economic Hedges The Company purchases certain commodities, primarily natural gas, to operate facilities and generate heat and steam for various manufacturing processes, which purchases are subject to price volatility. In order to manage the risk of price fluctuations associated with these commodity purchases, as deemed appropriate, the Company may enter into commodity swaps, forward contracts, or options. As of March 31, 2023, the Company had open commodity swap agreements, which effectively convert a portion of its natural gas costs into a fixed rate obligation. These commodity derivatives are designated as cash flow hedges, and as such, the contracts are marked-to-market at each reporting date and any unrealized gains or losses are included in AOCI to the extent effective, and reclassified to cost of sales in the period during which the transaction affects earnings or it becomes probable that the forecasted transaction will not occur. Open commodity cash flow hedges as of March 31, 2023 had maturities occurring over a period of 21 months and had a notional value of approximately 964 thousand megawatt hours of natural gas purchases. The Company may also enter into certain commodity swap agreements to economically hedge the impact of these price fluctuations, which are not designated for hedge accounting treatment. Open commodity economic hedges as of March 31, 2023 had maturities occurring over a period of 24 months and had a notional value of approximately 895 thousand megawatt hours of natural gas purchases. Interest Rate Swaps On September 6, 2017, the Company issued the 2024 Term Loan B, which currently bears an interest rate of LIBOR plus 2.00%, subject to a 0.00% LIBOR floor. In order to reduce the variability in interest payments associated with the Company’s variable rate debt, during 2017 the Company entered into certain interest rate swap agreements to convert a portion of these variable rate borrowings into a fixed rate obligation. These interest rate swap agreements are designated as cash flow hedges, and as such, the contracts are marked-to-market at each reporting date and any unrealized gains or losses are included in AOCI to the extent effective, and reclassified to interest expense in the period during which the transaction affects earnings or it becomes probable that the forecasted transaction will not occur. Under the terms of the swap agreements, with a net notional U.S. dollar equivalent of $200.0 million and an effective date of September 29, 2017, the Company was required to pay the counterparties a stream of fixed interest payments at a rate of 1.81%, and in turn, receives variable interest payments based on 1-month LIBOR from the counterparties. These interest rate swap agreements matured in September 2022, and the Company has no remaining open interest rate swap agreements. Net Investment Hedge The Company accounts for its cross currency swaps (“CCS”) under the spot method, meaning that changes in the fair value of the hedge included in the assessment of effectiveness (changes due to spot foreign exchange rates) are recorded within AOCI, where they remain until either the sale or substantially complete liquidation of the subsidiary subject to the hedge. Additionally, the initial value of any component excluded from the assessment of effectiveness is recognized in income using a systematic and rational method over the life of the hedging instrument and any difference between the change in the fair value of the excluded component and amounts recognized in income under that systematic and rational method is recognized in AOCI. When applicable, the Company amortizes any initial excluded component value of a CCS as a reduction of “Interest expense, net” in the condensed consolidated statements of operations using the straight-line method over the remaining term of the related CCS. Additionally, interest receipts and payments are accrued under the terms of the Company’s CCS and are recognized within “Interest expense, net” in the condensed consolidated statements of operations. The Company entered into a CCS arrangement (the “2017 CCS”) on September 1, 2017, swapping U.S. dollar principal and interest payments of $500.0 million at an interest rate of 5.375% on its 2025 Senior Notes for euro-denominated payments of €420.0 million at a weighted average interest rate of 3.45% for approximately five years. On February 26, 2020, the Company settled its 2017 CCS and replaced it with a new CCS arrangement (the “2020 CCS”) that carried substantially the same terms as the 2017 CCS. Under the 2020 CCS, the Company notionally exchanged $500.0 million at an interest rate of 5.375% for €459.3 million at a weighted average interest rate of 3.672% for approximately 2.7 years, with a final maturity of November 3, 2022. The cash flows under the 2020 CCS are aligned with the Company’s principal and interest obligations on its 5.375% 2025 Senior Notes. On April 7, 2022, the Company settled its existing 2020 CCS, which were set to mature in November 2022. Upon settlement of the 2020 CCS, the Company realized net cash proceeds of $1.9 million. ​ Summary of Derivative Instruments The following table presents the effect of the Company’s derivative instruments, including those not designated for hedge accounting treatment, on the condensed consolidated statements of operations for the three months ended March 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Location and Amount of Gain (Loss) Recognized in Statements of Operations ​ ​ Three Months Ended ​ Three Months Ended ​ ​ March 31, 2023 ​ March 31, 2022 ​ Cost of sales ​ Interest expense, net ​ Other (expense) income, net ​ Cost of sales ​ Interest expense, net ​ Other (expense) income, net Total amount of income and (expense) line items presented in the statements of operations in which the effects of derivative instruments are recorded ​ $ (959.1) ​ $ (38.3) ​ $ 2.9 ​ $ (1,210.7) ​ $ (21.9) ​ $ (3.0) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The effects of cash flow hedge instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity cash flow hedges ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of loss reclassified from AOCI into income ​ $ (6.4) ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — Interest rate swaps ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of loss reclassified from AOCI into income ​ $ — ​ $ — ​ $ — ​ $ — ​ $ (0.8) ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The effects of net investment hedge instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cross currency swaps ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of gain excluded from effectiveness testing ​ $ — ​ $ — ​ $ — ​ $ — ​ $ 2.1 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The effects of derivatives not designated as hedge instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign exchange forward contracts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of gain (loss) recognized in income ​ $ — ​ $ — ​ $ (7.8) ​ $ — ​ $ — ​ $ 8.8 Commodity economic hedges ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of loss recognized in income ​ $ (12.4) ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​ The following table presents the effect of cash flow and net investment hedge accounting on AOCI for the three months ended March 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ` ​ Gain (Loss) Recognized in AOCI on Balance Sheet ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2023 ​ 2022 Designated as Cash Flow Hedges ​ ​ ​ ​ ​ ​ Commodity cash flow hedges ​ $ (9.9) ​ $ — Interest rate swaps ​ ​ — ​ ​ 1.5 Total ​ $ (9.9) ​ $ 1.5 Designated as Net Investment Hedges ​ ​ ​ ​ ​ ​ Cross currency swaps (CCS) ​ $ — ​ $ 6.1 Total ​ $ — ​ $ 6.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gain (Loss) Recognized in Other expense (income), net in Statement of Operations ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ ​ 2023 2022 Settlements and changes in the fair value of forward contracts (not designated as hedges) $ (7.8) $ 8.8 Remeasurement of foreign currency-denominated assets and liabilities ​ $ 10.5 ​ $ (10.2) ​ ​ Total ​ $ 2.7 ​ $ (1.4) ​ ​ ​ The Company expects to reclassify in the next twelve months an approximate $23.0 million net loss from AOCI into earnings related to the Company’s outstanding commodity cash flow hedges as of March 31, 2023, based on current commodity price indices. The following tables summarize the gross and net unrealized gains and losses, as well as the balance sheet classification, of outstanding derivatives recorded in the condensed consolidated balance sheets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ ​ Foreign ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Exchange ​ Commodity ​ Commodity ​ ​ ​ Balance Sheet ​ Forward ​ Economic ​ Cash Flow ​ ​ Classification Contracts ​ Hedges ​ Hedges ​ Total Asset Derivatives: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts receivable, net of allowance ​ $ 0.1 ​ $ — ​ $ 0.1 ​ $ 0.2 Gross derivative asset position ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ 0.2 Less: Counterparty netting ​ ​ (0.1) ​ ​ — ​ ​ (0.1) ​ ​ (0.2) Net derivative asset position ​ $ — ​ $ — ​ $ — ​ $ — Liability Derivatives: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable ​ $ (12.5) ​ $ (13.5) ​ $ (23.1) ​ $ (49.1) Other noncurrent obligations ​ ​ — ​ ​ (1.9) ​ ​ (2.5) ​ ​ (4.4) Gross derivative liability position ​ ​ (12.5) ​ ​ (15.4) ​ ​ (25.6) ​ ​ (53.5) Less: Counterparty netting ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ 0.2 Net derivative liability position ​ $ (12.4) ​ $ (15.4) ​ $ (25.5) ​ $ (53.3) Total net derivative position ​ $ (12.4) ​ $ (15.4) ​ $ (25.5) ​ $ (53.3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ Foreign ​ ​ ​ ​ ​ ​ ​ ​ Exchange ​ Commodity ​ Commodity ​ ​ ​ ​ Balance Sheet ​ Forward ​ Economic ​ Cash Flow ​ ​ Classification Contracts Hedges Hedges Total Asset Derivatives: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts receivable, net of allowance ​ $ 0.2 ​ $ — ​ $ — ​ $ 0.2 ​ Gross derivative asset position ​ ​ 0.2 ​ ​ — ​ ​ — ​ ​ 0.2 ​ Less: Counterparty netting ​ ​ (0.1) ​ ​ — ​ ​ — ​ ​ (0.1) ​ Net derivative asset position ​ $ 0.1 ​ $ — ​ $ — ​ $ 0.1 ​ Liability Derivatives: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable ​ $ (11.1) ​ $ (5.3) ​ $ (11.3) ​ $ (27.7) ​ Other noncurrent obligations ​ ​ — ​ ​ (1.3) ​ ​ (0.9) ​ ​ (2.2) ​ Gross derivative liability position ​ ​ (11.1) ​ ​ (6.6) ​ ​ (12.2) ​ ​ (29.9) ​ Less: Counterparty netting ​ ​ 0.1 ​ ​ — ​ ​ — ​ ​ 0.1 ​ Net derivative liability position ​ $ (11.0) ​ $ (6.6) ​ $ (12.2) ​ $ (29.8) ​ Total net derivative position ​ $ (10.9) ​ $ (6.6) ​ $ (12.2) ​ $ (29.7) ​ ​ Forward contracts, interest rate swaps, commodity forward contracts, swaps, or options, and cross currency swaps are entered into with a limited number of counterparties, each of which allows for net settlement of all contracts through a single payment in a single currency in the event of a default on or termination of any one contract. As such, in accordance with the Company’s accounting policy, these derivative instruments are recorded on a net basis by counterparty within the condensed consolidated balance sheets. Refer to Notes 11 and 18 of the condensed consolidated financial statements for further information regarding the fair value of the Company’s derivative instruments and the related changes in AOCI.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2023
Fair Value Measurements
Fair Value Measurements	NOTE 11—FAIR VALUE MEASUREMENTS Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Assets and liabilities measured at fair value are classified using the following hierarchy, which is based upon the transparency of inputs to the valuation as of the measurement date. Level 1—Valuation is based upon quoted prices (unadjusted) for identical assets or liabilities in active markets. Level 2—Valuation is based upon quoted prices for similar assets and liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument. Level 3—Valuation is based upon other unobservable inputs that are significant to the fair value measurement. The following table summarizes the basis used to measure certain assets and liabilities at fair value on a recurring basis in the condensed consolidated balance sheets as of March 31, 2023 and December 31, 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ ​ Quoted Prices in Active Markets for Identical Items ​ Significant Other Observable Inputs ​ Significant Unobservable Inputs ​ ​ ​ Assets (Liabilities) at Fair Value (Level 1) (Level 2) (Level 3) Total Foreign exchange forward contracts—(Liabilities) ​ $ — ​ $ (12.4) ​ $ — ​ $ (12.4) ​ Commodity economic hedges—(Liabilities) ​ ​ — ​ ​ (15.4) ​ ​ — ​ ​ (15.4) ​ Commodity cash flow hedges—(Liabilities) ​ ​ — ​ ​ (25.5) ​ ​ — ​ ​ (25.5) ​ Total fair value ​ $ — ​ $ (53.3) ​ $ — ​ $ (53.3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ Quoted Prices in Active Markets for Identical Items ​ Significant Other Observable Inputs ​ Significant Unobservable Inputs ​ ​ ​ Assets (Liabilities) at Fair Value (Level 1) (Level 2) (Level 3) Total Foreign exchange forward contracts—Assets ​ $ — $ 0.1 $ — $ 0.1 ​ Foreign exchange forward contracts—(Liabilities) ​ ​ — ​ ​ (11.0) ​ ​ — ​ ​ (11.0) ​ Commodity economic hedges—(Liabilities) ​ ​ — ​ ​ (6.6) ​ ​ — ​ ​ (6.6) ​ Commodity cash flow hedges—(Liabilities) ​ ​ — ​ ​ (12.2) ​ ​ — ​ ​ (12.2) ​ Total fair value ​ $ — ​ $ (29.7) ​ $ — ​ $ (29.7) ​ ​ The Company uses an income approach to value its derivative instruments, utilizing discounted cash flow techniques, considering the terms of the contract and observable market information available as of the reporting date, such as interest rate yield curves and currency spot and forward rates. Significant inputs to the valuation for these derivative instruments are obtained from broker quotations or from listed or over-the-counter market data, and are classified as Level 2 in the fair value hierarchy. Nonrecurring Fair Value Measurements The Company measured certain financial assets at fair value on a nonrecurring basis during the year ended December 31, 2022, which were still held as of March 31, 2023. These financial assets represent the Company’s styrene monomer assets in Boehlen, Germany, which it continued to operate until the fourth quarter of 2022 when the Company decided to close this plant in connection with the asset restructuring plan. Refer to Note 17 for further information. These assets were measured at fair value using underlying fixed asset records in conjunction with the use of industry experience and available market data, which are classified as Level 3 significant unobservable inputs in the fair value hierarchy. During the three months ended March 31, 2023, the Company recorded additional impairment charges There were no other financial assets Fair Value of Debt Instruments The following table presents the estimated fair value of the Company’s outstanding debt not carried at fair value as of March 31, 2023 and December 31, 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ As of ​ March 31, 2023 December 31, 2022 2029 Senior Notes ​ $ 269.1 ​ $ 292.3 ​ 2028 Term Loan B ​ ​ 662.1 ​ ​ 687.1 ​ 2025 Senior Notes ​ ​ 406.8 ​ ​ 416.9 ​ 2024 Term Loan B ​ ​ 653.8 ​ ​ 645.6 ​ Total fair value ​ $ 1,991.8 ​ $ 2,041.9 ​ ​ The fair value of the Company’s debt facilities above (each Level 2 securities) is determined using over-the-counter market quotes and benchmark yields received from independent vendors. Fair value amount presented reflect the Company’s carrying value of debt, net of original issuance discount. There were no other significant financial instruments outstanding as of March 31, 2023 and December 31, 2022.

Provision For Income Taxes

Provision For Income Taxes	3 Months Ended
	Mar. 31, 2023
Provision For Income Taxes
Provision For Income Taxes	NOTE 12—PROVISION FOR INCOME TAXES ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ ​ 2023 2022 ​ Effective income tax rate ​ ​ 25.4 % ​ 56.9 % ​ ​ Benefit from income taxes for the three months ended March 31, 2023 totaled $16.7 million, resulting in an effective tax rate of 25.4%. Provision for income taxes for the three months ended March 31, 2022 totaled $22.6 million, resulting in an effective tax rate of 56.9%. The most significant driver of the decrease in the effective income tax rate for the three months ended March 31, 2023 compared to the prior year was the change in the Company’s forecasted jurisdictional mix of earnings, where income expected to be generated in higher rate jurisdictions exceeds income expected to be generated in lower rate jurisdictions, partially offset by losses not anticipated to provide a tax benefit. The effective income tax rate for the three months ended March 31, 2022 was primarily impacted by a $35.6 million charge related to the European Commission request for information, as described within Note 13 in the condensed consolidated financial statements, for which the Company estimates no tax benefit.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies.
Commitments and Contingencies	NOTE 13—COMMITMENTS AND CONTINGENCIES Environmental Matters Accruals for environmental matters are recorded when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated based on current law, existing technologies and other information. Pursuant to the terms of the agreement associated with the Company’s formation, the pre-closing environmental liabilities were retained by Dow, and Dow agreed, subject to temporal, monetary, and other limitations to indemnify the Company from and against environmental liabilities incurred or relating to the predecessor periods. Other than certain immaterial environmental liabilities assumed as part of the PMMA Acquisition and the Aristech Surfaces Acquisition, no material environmental claims have been asserted against the Company, and the Company does not have any material accrued obligations for any Superfund Sites. As of March 31, 2023 and December 31, 2022, the Company had $3.5 million of accrued obligations for environmental remediation or restoration costs, which were recorded at fair value within the opening balance sheets of the PMMA business and Aristech Surfaces during 2021. On March 24, 2023, due to equipment failure at the Bristol, Pennsylvania facility, operated by our wholly-owned subsidiary, Altuglas LLC, an accidental release of a latex emulsion product occurred, which ultimately flowed into a local waterway (the “Bristol Spill”). We reported the event and cooperated closely with local, state, and federal authorities on the response activities. Water sampling conducted by the authorities did not detect site-related material in the waterway. See “Litigation Matters” Inherent uncertainties exist in the Company’s potential environmental liabilities primarily due to unknown conditions, whether future claims may fall outside the scope of the indemnity, changing governmental regulations and legal standards regarding liability, and evolving technologies for handling site remediation and restoration. In connection with the Company’s existing indemnification, the possibility is considered remote that environmental remediation costs will have a material adverse impact on the condensed consolidated financial statements over the next 12 months. Purchase Commitments In the normal course of business, the Company has certain raw material purchase contracts where it is required to purchase certain minimum volumes at current market prices. These commitments range from one Asset Retirement Obligations The Company has built certain manufacturing facilities on leased land and is required to remove these facilities at the end of the corresponding contract term. Legal obligations for these demolition and decommissioning activities exist in connection with the retirement of these assets triggered upon closure of the facilities. In instances when the Company plans to continue operations at these facilities indefinitely, and therefore, a reasonable estimate of fair value cannot be determined, an asset retirement obligation is not recognized. In connection with the Asset Restructuring Plan as described within Note 17, the Company concluded the Boehlen, Germany site no longer had an indeterminate life. Accordingly, during the fourth quarter of 2022, the Company recorded the fair value of an asset retirement obligation and a corresponding asset retirement cost, which was capitalized as part of the carrying amount of the related long-lived assets and depreciated over the asset’s shortened useful life. The asset retirement cost was fully depreciated during the fourth quarter of 2022. ​ ​ ​ ​ ​ ​ ​ Balance at Change in asset retirement obligation ​ March 31, 2023 Balance at beginning of period ​ $ 35.8 Obligations incurred ​ ​ 0.9 Settlements ​ ​ (2.2) Accretion expense ​ ​ 0.5 Currency translation adjustment ​ ​ 0.6 Balance at end of period ​ $ 35.6 ​ Accretion expense is included within “Selling, general and administrative expenses” in the condensed consolidated statement of operations. The current portion of the asset retirement obligation is recorded within “Accrued expenses and other current liabilities” and the long-term portion is recorded within “Other noncurrent obligations” in the condensed consolidated balance sheets. As of March 31, 2023 and December 31, 2022, the current portion was $24.6 million and $25.3 million, respectively, and the long-term portion was $11.0 million and $10.5 million, respectively. Litigation Matters From time to time, the Company may be subject to various legal claims and proceedings incidental to the normal conduct of business, relating to such matters as employees, product liability, antitrust/competition, past waste disposal practices and release of chemicals into the environment. While it is impossible at this time to determine with certainty the ultimate outcome of these routine claims, the Company does not believe that the ultimate resolution of these claims will have a material adverse effect on the Company’s results of operations, financial condition or cash flow. Legal costs, including those legal costs expected to be incurred in connection with a loss contingency, are expensed as incurred. Legal Proceedings related to the Bristol Spill (a) Jonnie Helfrich v. Trinseo PLC (No. 2:23-cv-01525) (United States District Court for the Eastern District of Pennsylvania) On April 20, 2023, a complaint was filed which purports to be on behalf of a class of purchasers of the Company’s securities between May 3, 2021 and March 27, 2023. It names as defendants the Company and our chief executive officer and chief financial officer, and seeks unspecified damages and other relief for alleged violations of Sections 10(b) and 20(a) of, and Rule 10b-5 under, of the Securities Exchange Act of 1934. Given the early stage of this matter, we are not able to estimate whether a material loss to our business is probable or remote, or estimate a potential range of loss, if any. The Company intends to vigorously defend this action. (b) Timothy McGraw, Emily Cohen & Danielle Byrd v. Altuglas LLC and Trinseo LLC (Court of Common Pleas of Philadelphia County) On March 29, 2023, a putative class action complaint was filed which seeks to certify a class that could potentially include all persons and entities that reside in the area served by the Baxter Drinking Water Treatment Plant. The plaintiffs allege claims of breach of duty of care based on negligence as a result of the Bristol Spill, as well as other causes of action, and seek compensatory damages, restitution, or refund of damages, including actual, statutory, and punitive damages, as well as injunctive relief. Given the early stage of this matter, we are not able to estimate whether a material loss to our business is probable or remote, or estimate a potential range of loss, if any. The Company intends to vigorously defend this action. (c) Environmental Proceedings On March 25, 2023, the Company received a Notice of Federal Interest from the United States Coast Guard (“USCG”), identifying the Company as a “potentially responsible party” (“PRP”) related to the Bristol Spill. The Company also received a Notice of Federal Assumption and an Administrative Order, dated April 20, 2023 from the USCG, identifying the Company as a PRP related to the Bristol Spill. The USCG notices and order do not designate specific fines or penalties against the Company. It is not possible at this time for the Company to estimate its ultimate liability pursuant to the USCG notices or order, or other potential administrative actions related to the Bristol Spill, whether a material loss to our business is probable or remote, or estimate a potential range of loss, if any. Synthos Matter On November 21, 2022, the Company received formal notice from the German Arbitration Institute that Synthos had initiated an arbitration dispute on October 14, 2022 against Trinseo and its following subsidiaries: Trinseo Deutschland GmbH, Trinseo Belgium BV, Trinseo Europe GmbH, and Trinseo Export GmbH, related to Synthos’ purchase of Trinseo’s Rubber Business in 2021. As discussed in Note 4, Synthos and Trinseo are parties to an asset purchase agreement (“APA”) dated May 21, 2021, whereby Trinseo transferred its Rubber Business to Synthos, pending regulatory approval and other administrative pre-closing conditions, for an enterprise value of approximately $491.0 million. This transaction formally closed on December 1, 2021. Synthos claims that Trinseo did not properly disclose certain information including the natural gas pricing mechanism for the steam which is supplied by a third party to the Rubber Business. Synthos is seeking non-monetary restitution and monetary damages related to the spike of utility prices in Germany that commenced in the fall of 2021. The Company believes it has valid and prevailing defenses to Synthos’ claims and intends to vigorously defend itself against all allegations. European Commission Request for Information On June 6, 2018, Trinseo Europe GmbH, a subsidiary of the Company, received a request for information in the form of a letter from the European Commission Directorate General for Competition (the “European Commission”) related to styrene monomer commercial activity in the European Economic Area. The Company subsequently commenced an internal investigation into these commercial activities and discovered instances of inappropriate activity. As a result of further developments in this matter, during the first quarter of 2022, the Company recorded a charge of $35.6 million which is included within “Impairment and other charges” on the condensed consolidated statements of operations. In November 2022, the Company reached a final settlement with the European Commission in respect of this matter of $33.8 million, adjusted for foreign exchange rate impacts, which was subsequently paid in full in December 2022.

Pension Plans And Other Postret

Pension Plans And Other Postretirement Benefits	3 Months Ended
	Mar. 31, 2023
Pension Plans and Other Postretirement Benefits
Pension Plans and Other Postretirement Benefits	NOTE 14—PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS The components of net periodic benefit costs for all significant plans were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Three Months Ended ​ ​ ​ March 31, ​ March 31, ​ ​ ​ Non-U.S. Defined Benefit Pension Plans ​ U.S. Defined Benefit Pension ​ ​ 2023 2022 2023 2022 Net periodic benefit cost ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service cost ​ $ 2.0 ​ $ 3.2 $ 0.1 ​ $ 0.2 ​ Interest cost ​ 1.7 ​ 0.7 ​ 0.2 ​ 0.2 ​ Expected return on plan assets ​ (0.2) ​ (0.1) ​ (0.1) ​ (0.2) ​ Amortization of prior service credit ​ (0.1) ​ (0.1) ​ — ​ — ​ Amortization of net loss ​ (0.8) ​ 0.7 ​ — ​ — ​ Net periodic benefit cost ​ $ 2.6 ​ $ 4.4 ​ $ 0.2 ​ $ 0.2 ​ ​ The Company had less than $0.2 million of net periodic benefit costs for its other postretirement plans for the three months ended March 31, 2023 and 2022. Service cost related to the Company’s defined benefit pension plans and other postretirement plans is included within “Cost of sales” and “Selling, general and administrative expenses,” whereas all other components of net periodic benefit cost are included within “Other expense (income), net” in the condensed consolidated statements of operations. As of March 31, 2023 and December 31, 2022, the Company’s benefit obligations included primarily in “Other noncurrent obligations” in the condensed consolidated balance sheets were $183.4 million and $177.8 million, respectively. The Company made cash contributions and benefit payments to unfunded plans of approximately $1.7 million during the three months ended March 31, 2023. The Company expects to make additional cash contributions, including benefit payments to unfunded plans, of approximately $11.4 million to its defined benefit plans for the remainder of 2023.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2023
Share-Based Compensation.
Share-Based Compensation	NOTE 15—SHARE-BASED COMPENSATION Refer to the Annual Report for definitions of capitalized terms not included herein and further background on the Company’s share-based compensation programs included in the tables below. The following table summarizes the Company’s share-based compensation expense for the three months ended March 31, 2023 and 2022, as well as unrecognized compensation cost as of March 31, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ ​ Three Months Ended ​ March 31, 2023 ​ ​ ​ March 31, ​ Unrecognized ​ Weighted ​ ​ 2023 2022 Compensation Cost Average Years ​ RSUs ​ $ 4.8 ​ $ 4.6 ​ $ 13.5 ​ 2.0 ​ Options ​ ​ 2.6 ​ ​ 3.0 ​ ​ 3.9 ​ 1.6 ​ PSUs ​ ​ 0.8 ​ ​ 0.7 ​ ​ 7.4 ​ 2.4 ​ Total share-based compensation expense ​ $ 8.2 ​ $ 8.3 ​ ​ ​ ​ ​ ​ ​ The following table summarizes awards granted and the respective weighted average grant date fair value for the three months ended March 31, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, 2023 ​ ​ Awards Granted ​ Weighted Average Grant Date Fair Value per Award RSUs ​ ​ 394,292 ​ $ 24.10 Options ​ ​ 438,727 ​ ​ 10.86 PSUs ​ ​ 219,238 ​ ​ 20.23 ​ Option Awards The following are the weighted average assumptions used within the Black-Scholes pricing model for the Company’s option awards granted during the three months ended March 31, 2023: ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ March 31, 2023 Expected term (in years) 5.50 ​ Expected volatility 54.01 % Risk-free interest rate 4.06 % Dividend yield ​ 2.00 % ​ The expected volatility assumption is determined based on the historical volatility of the Company’s publicly traded ordinary shares. The expected term of option awards represents the period of time that option awards granted are expected to be outstanding. For the option awards granted during the three months ended March 31, 2023, the simplified method was used to calculate the expected term, given the Company’s limited historical exercise data. The risk-free interest rate for the periods within the expected term of option awards is based on the U.S. Treasury yield curve in effect at the time of grant. The dividend yield is estimated based on historical and expected dividend activity. Performance Share Units (PSUs) The following are the weighted average assumptions used within the Monte Carlo valuation model for PSUs granted during the three months ended March 31, 2023: ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, 2023 Expected term (in years) ​ 3.00 ​ Expected volatility 62.60 % Risk-free interest rate 4.41 % Share price $ 24.08 ​ ​ Determining the fair value of PSUs requires considerable judgment, including estimating the expected volatility of the price of the Company’s ordinary shares, the correlation between the Company’s share price and that of its peer companies, and the expected rate of interest. The expected volatility for each grant is determined based on the historical volatility of the Company’s ordinary shares. The expected term of PSUs represents the length of the performance period. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for a duration equivalent to the performance period. The share price is the closing price of the Company’s ordinary shares on the grant date.

Segments

Segments	3 Months Ended
	Mar. 31, 2023
Segments
Segments	NOTE 16—SEGMENTS The Company operates under six segments: Engineered Materials, Latex Binders, Plastics Solutions, Polystyrene, Feedstocks, and Americas Styrenics. On January 1, 2023, the Base Plastics segment was renamed to Plastics Solutions to better reflect Trinseo’s strategic focus on providing solutions in areas such as sustainability and material substitution. The Engineered Materials segment includes the Company’s compounds and blends products sold into higher growth and value applications, such as consumer electronics and medical, as well as soft thermoplastic elastomers (“TPEs”) products which are sold into markets such as footwear and automotive. Additionally, PMMA and MMA products, which are sold into a variety of applications including automotive, building & construction, medical, consumer electronics, and wellness, among others. The Latex Binders segment produces styrene-butadiene latex (“SB latex”) and other latex polymers and binders, primarily for coated paper and packaging board, carpet and artificial turf backings, as well as a number of performance latex binders applications, such as adhesive, building and construction and the technical textile paper market. The Plastics Solutions segment contains the results of the acrylonitrile-butadiene-styrene (“ABS”), styrene-acrylonitrile (“SAN”), and polycarbonate (“PC”) businesses, as well as compounds and blends for automotive and other applications. The Plastics Solutions segment also includes the results of Heathland, which was acquired in the first quarter of 2022. The Polystyrene segment includes a variety of general purpose polystyrenes (“GPPS”) and polystyrene that has been modified with polybutadiene rubber to increase its impact resistant properties (“HIPS”). The Feedstocks segment includes the Company’s production and procurement of styrene monomer outside of North America, which is used as a key raw material in many of the Company’s products, including polystyrene, SB latex, and ABS resins. Lastly, the Americas Styrenics segment consists solely of the operations of the Company’s The following table provides disclosure of the Company’s segment Adjusted EBITDA, which is used to measure segment operating performance and is defined below, for the three months ended March 31, 2023 and 2022. Asset and intersegment sales information by reporting segment is not regularly reviewed or included with the Company’s reporting to the chief operating decision maker. Therefore, this information has not been disclosed below. Refer to Note 5 for the Company’s net sales to external customers by segment for the three months ended March 31, 2023 and 2022. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Engineered ​ Latex ​ Plastics ​ ​ ​ ​ ​ Americas Three Months Ended (1) ​ Materials ​ Binders ​ Solutions ​ Polystyrene ​ Feedstocks ​ Styrenics March 31, 2023 $ (11.7) $ 26.0 ​ $ 25.6 ​ $ 15.7 $ (10.8) $ 17.6 ​ March 31, 2022 ​ $ 34.7 ​ $ 30.2 ​ $ 68.6 ​ $ 45.3 ​ $ 4.1 ​ $ 21.6 ​ (1) The Company’s primary measure of segment operating performance is Adjusted EBITDA, which is defined as income from continuing operations before interest expense, net; provision for income taxes; depreciation and amortization expense; loss on extinguishment of long-term debt; asset impairment charges; gains or losses on the dispositions of businesses and assets; restructuring charges; acquisition related costs and benefits and other items. Segment Adjusted EBITDA is a key metric that is used by management to evaluate business performance in comparison to budgets, forecasts, and prior year financial results, providing a measure that management believes reflects core operating performance by removing the impact of transactions and events that would not be considered a part of core operations. Other companies in the industry may define segment Adjusted EBITDA differently than the Company, and as a result, it may be difficult to use segment Adjusted EBITDA, or similarly named financial measures, that other companies may use to compare the performance of those companies to the Company’s segment performance. ​ The reconciliation of income from continuing operations before income taxes to segment Adjusted EBITDA is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Income (loss) from continuing operations before income taxes ​ $ (65.6) ​ $ 39.7 ​ Interest expense, net ​ 38.3 ​ 21.9 ​ Depreciation and amortization ​ ​ 56.0 ​ 53.0 ​ Corporate Unallocated (2) ​ ​ 26.1 ​ ​ 26.9 ​ Adjusted EBITDA Addbacks (3) ​ 7.6 ​ 63.0 ​ Segment Adjusted EBITDA ​ $ 62.4 ​ $ 204.5 ​ (2) Corporate unallocated includes corporate overhead costs and certain other income and expenses. (3) Adjusted EBITDA addbacks for the three months ended March 31, 2023 and 2022 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Net gain on disposition of businesses and assets ​ $ — ​ $ (0.3) ​ Restructuring and other charges (Note 17) ​ ​ 3.7 ​ ​ 0.4 ​ Acquisition transaction and integration net costs (Note 3) ​ ​ — ​ ​ 3.2 ​ Asset impairment charges or write-offs (Note 11) ​ ​ 0.3 ​ ​ 0.7 ​ European Commission request for information (Note 13) ​ ​ — ​ ​ 35.6 ​ Other items (a) ​ ​ 3.6 ​ ​ 23.4 ​ Total Adjusted EBITDA Addbacks ​ $ 7.6 ​ $ 63.0 ​ (a) Other items for the three months ended March 31, 2023 and 2022 primarily relate to fees incurred in conjunction with certain of the Company’s strategic initiatives, as well as our transition to a new enterprise resource planning system.

Restructuring

Restructuring	3 Months Ended
	Mar. 31, 2023
Restructuring
Restructuring	NOTE 17—RESTRUCTURING Refer to the Annual Report for further details regarding the Company’s previously announced restructuring activities included in the tables below. Restructuring charges are included within “Selling, general and administrative expenses” in the condensed consolidated statements of operations. The following table provides detail of the Company’s restructuring charges for the three months ended March 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Cumulative ​ ​ ​ ​ ​ March 31, ​ Life-to-date ​ ​ ​ ​ ​ 2023 2022 ​ Charges Segment ​ Asset Restructuring Plan (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Feedstocks: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accelerated depreciation ​ $ 0.9 ​ $ — ​ $ 36.0 ​ Feedstocks ​ Employee termination benefits ​ ​ (0.2) ​ ​ — ​ ​ 3.7 ​ Feedstocks ​ Contract terminations ​ ​ 2.5 ​ ​ — ​ ​ 2.9 ​ Feedstocks ​ Decommissioning and other ​ ​ 0.5 ​ ​ — ​ ​ 3.7 ​ Feedstocks ​ Plastics Solutions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accelerated depreciation ​ ​ — ​ ​ — ​ ​ 1.4 ​ Plastics Solutions ​ Employee termination benefits ​ ​ (0.4) ​ ​ — ​ ​ 3.0 ​ Plastics Solutions ​ Decommissioning and other ​ ​ 0.7 ​ ​ — ​ ​ 0.7 ​ Plastics Solutions ​ Engineered Materials: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accelerated depreciation ​ ​ 3.1 ​ ​ — ​ ​ 6.3 ​ Engineered Materials ​ Employee termination benefits ​ ​ — ​ ​ — ​ ​ 2.4 ​ Engineered Materials ​ Decommissioning and other ​ ​ 0.6 ​ ​ — ​ ​ 4.3 ​ Engineered Materials ​ Asset Restructuring Plan subtotal ​ $ 7.7 ​ $ — ​ $ 64.4 ​ ​ ​ Transformational Restructuring Program ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Employee termination benefits ​ $ — ​ $ 0.3 ​ $ 8.8 ​ ​ ​ Transformational Restructuring Program Subtotal ​ $ — ​ $ 0.3 ​ $ 8.8 ​ N/A (2) ​ Other Restructurings ​ ​ — ​ ​ 0.1 ​ ​ ​ ​ Various ​ Total Restructuring Charges ​ $ 7.7 ​ $ 0.4 ​ ​ ​ ​ ​ ​ (1) In December 2022, the Company announced an asset restructuring plan designed to reduce costs, improve profitability, reduce exposure to cyclical markets and elevated natural gas prices, and address market overcapacity. The asset restructuring plan includes (i) closure of manufacturing operations at the styrene production facility in Boehlen, Germany, (ii) closure of one of its production lines at the Stade, Germany polycarbonate plant, and (iii) closure of the PMMA sheet manufacturing site in Matamoros, Mexico. The program is expected to be substantially completed by the end of 2024. In connection with this restructuring plan, during the three months ended March 31, 2023, the Company incurred employee termination benefit charges of $(0.6) million, contract termination charges of $2.5 million, accelerated depreciation charges of $4.0 million, and decommissioning and other charges of $1.8 million. Production at all facilities have ceased and decommissioning activities are expected to continue through the end of 2024. The Company expects to incur incremental contract termination charges of $17.6 million, decommissioning and other charges of $2.2 million, as well as a limited amount of incremental employee termination benefit charges, the majority of which is expected to be paid by the end of 2024. Of the total incremental charges, $18.6 million is expected to be incurred in the Feedstocks segment, and $1.2 million is expected to be incurred in the Plastics Solution segment. On April 4, 2023, the Company entered into an agreement to sell its land, buildings and equipment in Matamoros, Mexico for a cash consideration of approximately $19.0 million. The transaction is expected to close within the second quarter of 2023. (2) In May 2021, the Company approved a transformational restructuring program associated with the Company’s strategic initiatives. The Company expects to incur incremental employee termination benefit charges related to impacted employees as of March 31, 2023 of less than $1.0 million, the majority of which are expected to be paid in 2023. As this was identified as a corporate-related activity, the charges related to this restructuring program were not allocated to a specific segment, but rather included within corporate unallocated. Refer to Note 13 for further information regarding the asset retirement obligation. The following table provides a roll forward of the other liability balances associated with the Company’s restructuring activities as of March 31, 2023. Employee termination benefit and contract termination charges are primarily recorded within “Accrued expenses and other current liabilities” in the condensed consolidated balance sheets. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ ​ ​ Balance at ​ December 31, 2022 Expenses Deductions (1) March 31, 2023 Employee termination benefits ​ $ 13.3 ​ $ (0.6) ​ $ (2.1) ​ $ 10.6 ​ Contract terminations ​ — ​ 2.5 ​ (2.5) ​ — ​ Decommissioning and other ​ ​ — ​ ​ 1.8 ​ ​ (1.8) ​ ​ — ​ Total ​ $ 13.3 ​ $ 3.7 ​ $ (6.4) ​ $ 10.6 ​ (1) Primarily includes payments made against the existing accrual, as well as immaterial impacts of foreign currency remeasurement.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss).
Accumulated Other Comprehensive Income (Loss)	NOTE 18—ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The components of AOCI, net of income taxes, consisted of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Pension & Other ​ ​ ​ ​ ​ ​ ​ ​ Translation ​ Postretirement Benefit ​ ​ Cash Flow ​ ​ ​ ​ Three Months Ended March 31, 2023 and 2022 Adjustments Plans, Net ​ Hedges, Net Total Balance as of December 31, 2022 ​ $ (151.2) ​ $ 29.0 ​ $ (9.1) ​ $ (131.3) ​ Other comprehensive income (loss) ​ 10.5 ​ — ​ (13.2) ​ (2.7) ​ Amounts reclassified from AOCI to net income (1) ​ ​ — ​ ​ 0.3 ​ ​ 5.8 ​ ​ 6.1 ​ Balance as of March 31, 2023 ​ $ (140.7) ​ $ 29.3 ​ $ (16.5) ​ $ (127.9) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of December 31, 2021 ​ $ (114.3) ​ $ (33.6) ​ $ 0.7 ​ $ (147.2) ​ Other comprehensive income (loss) ​ (4.3) ​ — ​ 0.7 ​ (3.6) ​ Amounts reclassified from AOCI to net income (1) ​ ​ — ​ ​ 0.3 ​ ​ 0.8 ​ ​ 1.1 ​ Balance as of March 31, 2022 ​ $ (118.6) ​ $ (33.3) ​ $ 2.2 ​ $ (149.7) ​ ​ (1) The following is a summary of amounts reclassified from AOCI to net income (loss) for the three months ended March 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ ​ March 31, ​ Statements of Operations ​ AOCI Components 2023 2022 Classification ​ Cash flow hedging items ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity cash flow hedges ​ $ 6.4 ​ $ — ​ Cost of sales ​ Interest rate swaps ​ ​ — ​ ​ 0.8 ​ Interest expense, net ​ Total before tax ​ ​ 6.4 ​ ​ 0.8 ​ ​ ​ Tax effect ​ ​ (0.6) ​ ​ — ​ Provision for (benefit from) income taxes ​ Total, net of tax ​ $ 5.8 ​ $ 0.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of pension and other postretirement benefit plan items ​ ​ ​ ​ ​ ​ ​ ​ ​ Prior service cost (credit) ​ $ 0.1 ​ $ (0.1) ​ (a) ​ Net actuarial loss ​ ​ 0.3 ​ ​ 0.6 ​ (a) ​ Total before tax ​ ​ 0.4 ​ ​ 0.5 ​ ​ ​ Tax effect ​ ​ (0.1) ​ ​ (0.2) ​ Provision for (benefit from) income taxes ​ Total, net of tax ​ $ 0.3 ​ $ 0.3 ​ ​ ​ (a) These AOCI components are included in the computation of net periodic benefit costs (see Note 14). .

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2023
Earnings Per Share
Earnings Per Share	NOTE 19—EARNINGS PER SHARE Basic earnings per ordinary share (“basic EPS”) is computed by dividing net income available to ordinary shareholders by the weighted average number of the Company’s ordinary shares outstanding for the applicable period. Diluted earnings per ordinary share (“diluted EPS”) is calculated using net income available to ordinary shareholders divided by diluted weighted average ordinary shares outstanding during each period, which includes unvested RSUs, option awards, and PSUs. Diluted EPS considers the impact of potentially dilutive securities except in periods in which there is a loss from continuing operations because the inclusion of the potential ordinary shares would have an anti-dilutive effect. The following table presents basic EPS and diluted EPS for the three months ended March 31, 2023 and 2022. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ (in millions, except per share data) 2023 2022 Earnings: ​ ​ ​ ​ ​ ​ ​ Net income (loss) from continuing operations ​ $ (48.9) ​ $ 17.1 ​ Net loss from discontinued operations ​ ​ — ​ ​ (0.4) ​ Net income (loss) ​ $ (48.9) ​ $ 16.7 ​ Shares: ​ ​ ​ ​ ​ ​ ​ Weighted average ordinary shares outstanding ​ 35.0 ​ 37.3 ​ Dilutive effect of RSUs, option awards, and PSUs (1) ​ — ​ 0.8 ​ Diluted weighted average ordinary shares outstanding ​ 35.0 ​ 38.1 ​ Income (loss) per share: ​ ​ ​ ​ ​ ​ ​ Income (loss) per share—basic: ​ ​ ​ ​ ​ ​ ​ Continuing operations ​ $ (1.40) ​ $ 0.46 ​ Discontinued operations ​ ​ — ​ ​ (0.01) ​ Income (loss) per share—basic ​ $ (1.40) ​ $ 0.45 ​ Income (loss) per share—diluted: ​ ​ ​ ​ ​ ​ ​ Continuing operations ​ $ (1.40) ​ $ 0.45 ​ Discontinued operations ​ ​ — ​ ​ (0.01) ​ Income (loss) per share—diluted ​ $ (1.40) ​ $ 0.44 ​ (1) Refer to Note 15 for discussion of RSUs, option awards, and PSUs granted to certain Company directors and employees. As the Company recorded a net loss from continuing operations for the three months ended March 31, 2023, potential shares related to equity-based awards have been excluded from the calculation of diluted EPS, as doing so would be anti-dilutive. There were 0.9 million anti-dilutive shares that have been excluded from the computation of diluted earnings per share for the three months ended March 31, 2022.

Impairment and Other Charges

Impairment and Other Charges	3 Months Ended
	Mar. 31, 2023
Impairment and Other Charges.
Impairment and Other Charges	NOTE 20—IMPAIRMENT AND OTHER CHARGES ​ Impairment and other charges consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Asset impairment charges or write-offs (Note 11) ​ $ 0.3 ​ $ 0.7 ​ European Commission request for information (Note 13) ​ ​ — ​ ​ 35.6 ​ Total ​ $ 0.3 ​ $ 36.3 ​ ​

Recent Accounting Guidance (Pol

Recent Accounting Guidance (Policies)	3 Months Ended
	Mar. 31, 2023
Recent Accounting Guidance
Basis of Presentation	The unaudited interim condensed consolidated financial statements of Trinseo PLC and its subsidiaries (the “Company”) as of and for the periods ended March 31, 2023 and 2022 were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and reflect all adjustments, consisting only of normal recurring adjustments, which, in the opinion of management, are considered necessary for the fair statement of the results for the periods presented. Because they cover interim periods, the statements and related notes to the financial statements do not include all disclosures normally provided in annual financial statements, and therefore, these statements should be read in conjunction with the 2022 audited consolidated financial statements included within the Company’s Annual Report on Form 10-K (“Annual Report”) filed with the Securities and Exchange Commission (“SEC”) on February 27, 2023. The Company’s condensed consolidated financial statements presented herein reflect the latest estimates and assumptions made by management that affect the reported amounts and related disclosures as of and for the period ended March 31, 2023. However, actual results could differ from these estimates and assumptions. The December 31, 2022 condensed consolidated balance sheet data presented herein was derived from the Company’s December 31, 2022 audited consolidated financial statements, but does not include all disclosures required by GAAP for annual periods. Throughout this Quarterly Report, unless otherwise indicated, amounts and activity are presented on a continuing operations basis.

Divestitures and Discontinued_2

Divestitures and Discontinued Operations (Tables)	3 Months Ended
	Mar. 31, 2023
Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Summary of the assets and liabilities classified as held-for-sale and results reflected as discontinued operations	​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2022 Net sales $ 0.1 Cost of sales ​ 0.7 ​ Gross loss ​ (0.6) ​ Selling, general and administrative expenses ​ (0.2) ​ Operating loss ​ (0.4) ​ Other expense, net ​ ​ — ​ Loss from discontinued operations before income taxes ​ (0.4) ​ Provision for income taxes ​ — ​ Net loss from discontinued operations ​ $ (0.4) ​

Net Sales (Tables)

Net Sales (Tables)	3 Months Ended
	Mar. 31, 2023
Net Sales
Disaggregation of Revenue [Table Text Block]	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Engineered ​ Latex ​ Plastics ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Materials ​ Binders ​ Solutions ​ Polystyrene ​ Feedstocks ​ Total March 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ United States ​ $ 110.9 ​ $ 67.6 ​ $ 68.7 ​ $ — ​ $ 3.6 ​ $ 250.8 ​ Europe ​ 73.5 ​ 128.1 ​ 165.3 ​ 138.5 ​ 39.4 ​ 544.8 ​ Asia-Pacific ​ 18.9 ​ 50.7 ​ 27.8 ​ 70.6 ​ — ​ 168.0 ​ Rest of World ​ 2.9 ​ 1.7 ​ 28.1 ​ — ​ — ​ 32.7 ​ Total ​ $ 206.2 ​ $ 248.1 ​ $ 289.9 ​ $ 209.1 ​ $ 43.0 ​ $ 996.3 ​ March 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ United States ​ $ 138.4 ​ $ 82.2 ​ $ 84.5 ​ $ — ​ $ 3.9 ​ $ 309.0 ​ Europe ​ 118.7 ​ 150.9 ​ 246.6 ​ 214.6 ​ 66.4 ​ 797.2 ​ Asia-Pacific ​ 35.3 ​ 71.7 ​ 37.2 ​ 103.4 ​ — ​ ​ 247.6 ​ Rest of World ​ 2.8 ​ 1.9 ​ 28.2 ​ — ​ — ​ 32.9 ​ Total ​ $ 295.2 ​ $ 306.7 ​ $ 396.5 ​ $ 318.0 ​ $ 70.3 ​ $ 1,386.7 ​

Investments in Unconsolidated_2

Investments in Unconsolidated Affiliates (Tables)	3 Months Ended
	Mar. 31, 2023
Investments in Unconsolidated Affiliates
Summarized financial information of unconsolidated affiliates	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Sales $ 443.3 $ 524.4 ​ Gross profit ​ $ 52.9 ​ $ 48.1 ​ Net income ​ $ 37.8 ​ $ 36.1 ​

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2023
Inventories
Schedule of Inventories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ 2023 ​ 2022 Finished goods $ 195.3 $ 218.4 Raw materials and semi-finished goods ​ 265.9 ​ 295.6 Supplies ​ 41.4 ​ 39.6 Total ​ $ 502.6 ​ $ 553.6

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2023
Debt
Schedule of Debt	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ December 31, 2022 ​ ​ Interest Rate as of March 31, 2023 Maturity Date Carrying Amount Unamortized Deferred Financing Fees (1) Total Debt, Less Unamortized Deferred Financing Fees Carrying Amount Unamortized Deferred Financing Fees (1) Total Debt, Less Unamortized Deferred Financing Fees ​ Senior Credit Facility ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2024 Term Loan B ​ 6.840% ​ September 2024 ​ $ 661.7 ​ $ (4.4) ​ $ 657.3 ​ $ 663.4 ​ $ (5.1) ​ $ 658.3 ​ 2028 Term Loan B ​ 7.340% ​ May 2028 ​ ​ 734.1 ​ ​ (13.8) ​ ​ 720.3 ​ ​ 735.9 ​ ​ (14.4) ​ ​ 721.5 ​ 2026 Revolving Facility (2) ​ Various ​ May 2026 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ 2029 Senior Notes ​ 5.125% ​ April 2029 ​ ​ 447.0 ​ ​ (12.5) ​ ​ 434.5 ​ ​ 447.0 ​ ​ (12.9) ​ ​ 434.1 ​ 2025 Senior Notes ​ 5.375% ​ September 2025 ​ ​ 500.0 ​ ​ (3.4) ​ ​ 496.6 ​ ​ 500.0 ​ ​ (3.7) ​ ​ 496.3 ​ Accounts Receivable Securitization Facility (3) ​ Various ​ November 2024 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ Other indebtedness ​ Various ​ Various ​ ​ 7.8 ​ ​ — ​ ​ 7.8 ​ ​ 7.4 ​ ​ — ​ ​ 7.4 ​ Total debt ​ ​ ​ ​ ​ $ 2,350.6 ​ $ (34.1) ​ $ 2,316.5 ​ $ 2,353.7 ​ $ (36.1) ​ $ 2,317.6 ​ Less: current portion (4) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (16.6) ​ ​ ​ ​ ​ ​ ​ ​ (16.0) ​ Total long-term debt, net of unamortized deferred financing fees ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 2,299.9 ​ ​ ​ ​ ​ ​ ​ $ 2,301.6 ​ (1) This caption does not include deferred financing fees related to the Company’s revolving facilities, which are included within “Deferred charges and other assets” on the condensed consolidated balance sheets. (2) As of March 31, 2023, under the 2026 Revolving Facility, the Company had a capacity of $375.0 million and $22.0 million outstanding letters of credit. As of March 31, 2023, the Company had funds available for borrowing of $100.5 million (net of the applicable $12.0 million outstanding letters of credit as defined in the secured credit agreement), which reflects the borrowing limit imposed by the springing covenant. The springing covenant applies when 30% or more of the 2026 Revolving Facility’s capacity is drawn which then requires the Company to meet a first lien net leverage ratio (as defined in the secured credit agreement) not to exceed 3.50 x at the end of each financial quarter. As of March 31, 2023, the first lien net leverage ratio was 4.85 x and the outstanding borrowings did not exceed the 30% threshold. Additionally, the Company is required to pay a quarterly commitment fee in respect of any unused commitments under this facility equal to 0.375% per annum. (3) As of March 31, 2023, this facility had a borrowing capacity of $150.0 million, and the Company had approximately $150.0 million of accounts receivable available to support this facility, based on the pool of eligible accounts receivable. (4) The current portion of long-term debt was primarily related to $14.5 million of the scheduled future principal payments on both the 2024 Term Loan B and 2028 Term Loan B as of March 31, 2023 and December 31, 2022.

Goodwill (Tables)

Goodwill (Tables)	3 Months Ended
	Mar. 31, 2023
Goodwill and Intangible assets
Changes in Carrying Amount of Goodwill, by Segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Engineered ​ Latex ​ Plastics ​ ​ ​ ​ ​ Americas ​ ​ ​ ​ Materials Binders Solutions Polystyrene Feedstocks Styrenics Total Balance at December 31, 2022 ​ $ 348.9 ​ $ 14.8 ​ $ 42.5 ​ $ 4.2 ​ $ — ​ $ — ​ $ 410.4 ​ Foreign currency impact ​ 2.6 ​ ​ 0.3 ​ ​ 0.8 ​ ​ 0.1 ​ ​ — ​ ​ — ​ 3.8 ​ Balance at March 31, 2023 ​ $ 351.5 ​ $ 15.1 ​ $ 43.3 ​ $ 4.3 ​ $ — ​ $ — ​ $ 414.2 ​ ​

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2023
Derivative Instruments
Notional Amounts of Most Significant Net Foreign Exchange Hedge Positions Outstanding	​ ​ ​ ​ ​ ​ ​ March 31, Buy / (Sell) 2023 Euro ​ $ (520.9) Chinese Yuan ​ $ (48.4) South Korean Won ​ $ (21.8) Swiss Franc ​ $ (19.6) Swedish Krona ​ $ 14.7
Schedule of Effect of Derivative Instruments on Statements of Operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Location and Amount of Gain (Loss) Recognized in Statements of Operations ​ ​ Three Months Ended ​ Three Months Ended ​ ​ March 31, 2023 ​ March 31, 2022 ​ Cost of sales ​ Interest expense, net ​ Other (expense) income, net ​ Cost of sales ​ Interest expense, net ​ Other (expense) income, net Total amount of income and (expense) line items presented in the statements of operations in which the effects of derivative instruments are recorded ​ $ (959.1) ​ $ (38.3) ​ $ 2.9 ​ $ (1,210.7) ​ $ (21.9) ​ $ (3.0) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The effects of cash flow hedge instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity cash flow hedges ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of loss reclassified from AOCI into income ​ $ (6.4) ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — Interest rate swaps ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of loss reclassified from AOCI into income ​ $ — ​ $ — ​ $ — ​ $ — ​ $ (0.8) ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The effects of net investment hedge instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cross currency swaps ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of gain excluded from effectiveness testing ​ $ — ​ $ — ​ $ — ​ $ — ​ $ 2.1 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The effects of derivatives not designated as hedge instruments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign exchange forward contracts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of gain (loss) recognized in income ​ $ — ​ $ — ​ $ (7.8) ​ $ — ​ $ — ​ $ 8.8 Commodity economic hedges ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of loss recognized in income ​ $ (12.4) ​ $ — ​ $ — ​ $ — ​ $ — ​ $ — ​
Schedule of Effect of Hedges on AOCI	​ ​ ​ ​ ​ ​ ​ ​ ` ​ Gain (Loss) Recognized in AOCI on Balance Sheet ​ ​ Three Months Ended ​ ​ March 31, ​ ​ 2023 ​ 2022 Designated as Cash Flow Hedges ​ ​ ​ ​ ​ ​ Commodity cash flow hedges ​ $ (9.9) ​ $ — Interest rate swaps ​ ​ — ​ ​ 1.5 Total ​ $ (9.9) ​ $ 1.5 Designated as Net Investment Hedges ​ ​ ​ ​ ​ ​ Cross currency swaps (CCS) ​ $ — ​ $ 6.1 Total ​ $ — ​ $ 6.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gain (Loss) Recognized in Other expense (income), net in Statement of Operations ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ ​ 2023 2022 Settlements and changes in the fair value of forward contracts (not designated as hedges) $ (7.8) $ 8.8 Remeasurement of foreign currency-denominated assets and liabilities ​ $ 10.5 ​ $ (10.2) ​ ​ Total ​ $ 2.7 ​ $ (1.4) ​ ​ ​
Schedule of Gross and Net Unrealized Gains and Losses and Balance Sheet Classification	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ ​ Foreign ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Exchange ​ Commodity ​ Commodity ​ ​ ​ Balance Sheet ​ Forward ​ Economic ​ Cash Flow ​ ​ Classification Contracts ​ Hedges ​ Hedges ​ Total Asset Derivatives: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts receivable, net of allowance ​ $ 0.1 ​ $ — ​ $ 0.1 ​ $ 0.2 Gross derivative asset position ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ 0.2 Less: Counterparty netting ​ ​ (0.1) ​ ​ — ​ ​ (0.1) ​ ​ (0.2) Net derivative asset position ​ $ — ​ $ — ​ $ — ​ $ — Liability Derivatives: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable ​ $ (12.5) ​ $ (13.5) ​ $ (23.1) ​ $ (49.1) Other noncurrent obligations ​ ​ — ​ ​ (1.9) ​ ​ (2.5) ​ ​ (4.4) Gross derivative liability position ​ ​ (12.5) ​ ​ (15.4) ​ ​ (25.6) ​ ​ (53.5) Less: Counterparty netting ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ 0.2 Net derivative liability position ​ $ (12.4) ​ $ (15.4) ​ $ (25.5) ​ $ (53.3) Total net derivative position ​ $ (12.4) ​ $ (15.4) ​ $ (25.5) ​ $ (53.3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ Foreign ​ ​ ​ ​ ​ ​ ​ ​ Exchange ​ Commodity ​ Commodity ​ ​ ​ ​ Balance Sheet ​ Forward ​ Economic ​ Cash Flow ​ ​ Classification Contracts Hedges Hedges Total Asset Derivatives: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts receivable, net of allowance ​ $ 0.2 ​ $ — ​ $ — ​ $ 0.2 ​ Gross derivative asset position ​ ​ 0.2 ​ ​ — ​ ​ — ​ ​ 0.2 ​ Less: Counterparty netting ​ ​ (0.1) ​ ​ — ​ ​ — ​ ​ (0.1) ​ Net derivative asset position ​ $ 0.1 ​ $ — ​ $ — ​ $ 0.1 ​ Liability Derivatives: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accounts payable ​ $ (11.1) ​ $ (5.3) ​ $ (11.3) ​ $ (27.7) ​ Other noncurrent obligations ​ ​ — ​ ​ (1.3) ​ ​ (0.9) ​ ​ (2.2) ​ Gross derivative liability position ​ ​ (11.1) ​ ​ (6.6) ​ ​ (12.2) ​ ​ (29.9) ​ Less: Counterparty netting ​ ​ 0.1 ​ ​ — ​ ​ — ​ ​ 0.1 ​ Net derivative liability position ​ $ (11.0) ​ $ (6.6) ​ $ (12.2) ​ $ (29.8) ​ Total net derivative position ​ $ (10.9) ​ $ (6.6) ​ $ (12.2) ​ $ (29.7) ​ ​

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2023
Fair Value Measurements
Schedule of Assets and Liabilities at Fair Value on Recurring Basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2023 ​ ​ Quoted Prices in Active Markets for Identical Items ​ Significant Other Observable Inputs ​ Significant Unobservable Inputs ​ ​ ​ Assets (Liabilities) at Fair Value (Level 1) (Level 2) (Level 3) Total Foreign exchange forward contracts—(Liabilities) ​ $ — ​ $ (12.4) ​ $ — ​ $ (12.4) ​ Commodity economic hedges—(Liabilities) ​ ​ — ​ ​ (15.4) ​ ​ — ​ ​ (15.4) ​ Commodity cash flow hedges—(Liabilities) ​ ​ — ​ ​ (25.5) ​ ​ — ​ ​ (25.5) ​ Total fair value ​ $ — ​ $ (53.3) ​ $ — ​ $ (53.3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ Quoted Prices in Active Markets for Identical Items ​ Significant Other Observable Inputs ​ Significant Unobservable Inputs ​ ​ ​ Assets (Liabilities) at Fair Value (Level 1) (Level 2) (Level 3) Total Foreign exchange forward contracts—Assets ​ $ — $ 0.1 $ — $ 0.1 ​ Foreign exchange forward contracts—(Liabilities) ​ ​ — ​ ​ (11.0) ​ ​ — ​ ​ (11.0) ​ Commodity economic hedges—(Liabilities) ​ ​ — ​ ​ (6.6) ​ ​ — ​ ​ (6.6) ​ Commodity cash flow hedges—(Liabilities) ​ ​ — ​ ​ (12.2) ​ ​ — ​ ​ (12.2) ​ Total fair value ​ $ — ​ $ (29.7) ​ $ — ​ $ (29.7) ​
Estimated Fair Value of Outstanding Debt Not Carried at Fair Value	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ As of ​ March 31, 2023 December 31, 2022 2029 Senior Notes ​ $ 269.1 ​ $ 292.3 ​ 2028 Term Loan B ​ ​ 662.1 ​ ​ 687.1 ​ 2025 Senior Notes ​ ​ 406.8 ​ ​ 416.9 ​ 2024 Term Loan B ​ ​ 653.8 ​ ​ 645.6 ​ Total fair value ​ $ 1,991.8 ​ $ 2,041.9 ​

Provision For Income Taxes (Tab

Provision For Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2023
Provision For Income Taxes
Schedule of Effective Tax Rate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ March 31, ​ ​ ​ 2023 2022 ​ Effective income tax rate ​ ​ 25.4 % ​ 56.9 % ​ ​

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies.
Schedule of asset retirement cost	​ ​ ​ ​ ​ ​ ​ Balance at Change in asset retirement obligation ​ March 31, 2023 Balance at beginning of period ​ $ 35.8 Obligations incurred ​ ​ 0.9 Settlements ​ ​ (2.2) Accretion expense ​ ​ 0.5 Currency translation adjustment ​ ​ 0.6 Balance at end of period ​ $ 35.6

Pension Plans and Other Postr_2

Pension Plans and Other Postretirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2023
Pension Plans and Other Postretirement Benefits
Schedule of Net Periodic Benefit Costs	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Three Months Ended ​ ​ ​ March 31, ​ March 31, ​ ​ ​ Non-U.S. Defined Benefit Pension Plans ​ U.S. Defined Benefit Pension ​ ​ 2023 2022 2023 2022 Net periodic benefit cost ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service cost ​ $ 2.0 ​ $ 3.2 $ 0.1 ​ $ 0.2 ​ Interest cost ​ 1.7 ​ 0.7 ​ 0.2 ​ 0.2 ​ Expected return on plan assets ​ (0.2) ​ (0.1) ​ (0.1) ​ (0.2) ​ Amortization of prior service credit ​ (0.1) ​ (0.1) ​ — ​ — ​ Amortization of net loss ​ (0.8) ​ 0.7 ​ — ​ — ​ Net periodic benefit cost ​ $ 2.6 ​ $ 4.4 ​ $ 0.2 ​ $ 0.2 ​

Share-Based Compensation (Table

Share-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Share-Based Compensation Expense and Unrecognized Compensation Cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ ​ Three Months Ended ​ March 31, 2023 ​ ​ ​ March 31, ​ Unrecognized ​ Weighted ​ ​ 2023 2022 Compensation Cost Average Years ​ RSUs ​ $ 4.8 ​ $ 4.6 ​ $ 13.5 ​ 2.0 ​ Options ​ ​ 2.6 ​ ​ 3.0 ​ ​ 3.9 ​ 1.6 ​ PSUs ​ ​ 0.8 ​ ​ 0.7 ​ ​ 7.4 ​ 2.4 ​ Total share-based compensation expense ​ $ 8.2 ​ $ 8.3 ​ ​ ​ ​ ​ ​
Summary of Awards Granted and Weighted Average Grant-Date Fair Value	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, 2023 ​ ​ Awards Granted ​ Weighted Average Grant Date Fair Value per Award RSUs ​ ​ 394,292 ​ $ 24.10 Options ​ ​ 438,727 ​ ​ 10.86 PSUs ​ ​ 219,238 ​ ​ 20.23
Option Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Weighted-average Assumptions	​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ March 31, 2023 Expected term (in years) 5.50 ​ Expected volatility 54.01 % Risk-free interest rate 4.06 % Dividend yield ​ 2.00 %
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Weighted-average Assumptions	​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, 2023 Expected term (in years) ​ 3.00 ​ Expected volatility 62.60 % Risk-free interest rate 4.41 % Share price $ 24.08 ​

Segments (Tables)

Segments (Tables)	3 Months Ended
	Mar. 31, 2023
Segments
Reconciliation of Segment Reporting to Consolidated	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Engineered ​ Latex ​ Plastics ​ ​ ​ ​ ​ Americas Three Months Ended (1) ​ Materials ​ Binders ​ Solutions ​ Polystyrene ​ Feedstocks ​ Styrenics March 31, 2023 $ (11.7) $ 26.0 ​ $ 25.6 ​ $ 15.7 $ (10.8) $ 17.6 ​ March 31, 2022 ​ $ 34.7 ​ $ 30.2 ​ $ 68.6 ​ $ 45.3 ​ $ 4.1 ​ $ 21.6 ​ (1) The Company’s primary measure of segment operating performance is Adjusted EBITDA, which is defined as income from continuing operations before interest expense, net; provision for income taxes; depreciation and amortization expense; loss on extinguishment of long-term debt; asset impairment charges; gains or losses on the dispositions of businesses and assets; restructuring charges; acquisition related costs and benefits and other items. Segment Adjusted EBITDA is a key metric that is used by management to evaluate business performance in comparison to budgets, forecasts, and prior year financial results, providing a measure that management believes reflects core operating performance by removing the impact of transactions and events that would not be considered a part of core operations. Other companies in the industry may define segment Adjusted EBITDA differently than the Company, and as a result, it may be difficult to use segment Adjusted EBITDA, or similarly named financial measures, that other companies may use to compare the performance of those companies to the Company’s segment performance. ​
Reconciliation of IBT to Adjusted EBITDA	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Income (loss) from continuing operations before income taxes ​ $ (65.6) ​ $ 39.7 ​ Interest expense, net ​ 38.3 ​ 21.9 ​ Depreciation and amortization ​ ​ 56.0 ​ 53.0 ​ Corporate Unallocated (2) ​ ​ 26.1 ​ ​ 26.9 ​ Adjusted EBITDA Addbacks (3) ​ 7.6 ​ 63.0 ​ Segment Adjusted EBITDA ​ $ 62.4 ​ $ 204.5 ​ (2) Corporate unallocated includes corporate overhead costs and certain other income and expenses. (3) Adjusted EBITDA addbacks for the three months ended March 31, 2023 and 2022 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Net gain on disposition of businesses and assets ​ $ — ​ $ (0.3) ​ Restructuring and other charges (Note 17) ​ ​ 3.7 ​ ​ 0.4 ​ Acquisition transaction and integration net costs (Note 3) ​ ​ — ​ ​ 3.2 ​ Asset impairment charges or write-offs (Note 11) ​ ​ 0.3 ​ ​ 0.7 ​ European Commission request for information (Note 13) ​ ​ — ​ ​ 35.6 ​ Other items (a) ​ ​ 3.6 ​ ​ 23.4 ​ Total Adjusted EBITDA Addbacks ​ $ 7.6 ​ $ 63.0 ​ (a) Other items for the three months ended March 31, 2023 and 2022 primarily relate to fees incurred in conjunction with certain of the Company’s strategic initiatives, as well as our transition to a new enterprise resource planning system.

Restructuring (Tables)

Restructuring (Tables)	3 Months Ended
	Mar. 31, 2023
Restructuring
Detail of Restructuring Charges	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Cumulative ​ ​ ​ ​ ​ March 31, ​ Life-to-date ​ ​ ​ ​ ​ 2023 2022 ​ Charges Segment ​ Asset Restructuring Plan (1) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Feedstocks: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accelerated depreciation ​ $ 0.9 ​ $ — ​ $ 36.0 ​ Feedstocks ​ Employee termination benefits ​ ​ (0.2) ​ ​ — ​ ​ 3.7 ​ Feedstocks ​ Contract terminations ​ ​ 2.5 ​ ​ — ​ ​ 2.9 ​ Feedstocks ​ Decommissioning and other ​ ​ 0.5 ​ ​ — ​ ​ 3.7 ​ Feedstocks ​ Plastics Solutions: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accelerated depreciation ​ ​ — ​ ​ — ​ ​ 1.4 ​ Plastics Solutions ​ Employee termination benefits ​ ​ (0.4) ​ ​ — ​ ​ 3.0 ​ Plastics Solutions ​ Decommissioning and other ​ ​ 0.7 ​ ​ — ​ ​ 0.7 ​ Plastics Solutions ​ Engineered Materials: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accelerated depreciation ​ ​ 3.1 ​ ​ — ​ ​ 6.3 ​ Engineered Materials ​ Employee termination benefits ​ ​ — ​ ​ — ​ ​ 2.4 ​ Engineered Materials ​ Decommissioning and other ​ ​ 0.6 ​ ​ — ​ ​ 4.3 ​ Engineered Materials ​ Asset Restructuring Plan subtotal ​ $ 7.7 ​ $ — ​ $ 64.4 ​ ​ ​ Transformational Restructuring Program ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Employee termination benefits ​ $ — ​ $ 0.3 ​ $ 8.8 ​ ​ ​ Transformational Restructuring Program Subtotal ​ $ — ​ $ 0.3 ​ $ 8.8 ​ N/A (2) ​ Other Restructurings ​ ​ — ​ ​ 0.1 ​ ​ ​ ​ Various ​ Total Restructuring Charges ​ $ 7.7 ​ $ 0.4 ​ ​ ​ ​ ​ ​ (1) In December 2022, the Company announced an asset restructuring plan designed to reduce costs, improve profitability, reduce exposure to cyclical markets and elevated natural gas prices, and address market overcapacity. The asset restructuring plan includes (i) closure of manufacturing operations at the styrene production facility in Boehlen, Germany, (ii) closure of one of its production lines at the Stade, Germany polycarbonate plant, and (iii) closure of the PMMA sheet manufacturing site in Matamoros, Mexico. The program is expected to be substantially completed by the end of 2024. In connection with this restructuring plan, during the three months ended March 31, 2023, the Company incurred employee termination benefit charges of $(0.6) million, contract termination charges of $2.5 million, accelerated depreciation charges of $4.0 million, and decommissioning and other charges of $1.8 million. Production at all facilities have ceased and decommissioning activities are expected to continue through the end of 2024. The Company expects to incur incremental contract termination charges of $17.6 million, decommissioning and other charges of $2.2 million, as well as a limited amount of incremental employee termination benefit charges, the majority of which is expected to be paid by the end of 2024. Of the total incremental charges, $18.6 million is expected to be incurred in the Feedstocks segment, and $1.2 million is expected to be incurred in the Plastics Solution segment. On April 4, 2023, the Company entered into an agreement to sell its land, buildings and equipment in Matamoros, Mexico for a cash consideration of approximately $19.0 million. The transaction is expected to close within the second quarter of 2023. (2) In May 2021, the Company approved a transformational restructuring program associated with the Company’s strategic initiatives. The Company expects to incur incremental employee termination benefit charges related to impacted employees as of March 31, 2023 of less than $1.0 million, the majority of which are expected to be paid in 2023. As this was identified as a corporate-related activity, the charges related to this restructuring program were not allocated to a specific segment, but rather included within corporate unallocated.
Rollforward of Liability Balances	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ ​ ​ Balance at ​ December 31, 2022 Expenses Deductions (1) March 31, 2023 Employee termination benefits ​ $ 13.3 ​ $ (0.6) ​ $ (2.1) ​ $ 10.6 ​ Contract terminations ​ — ​ 2.5 ​ (2.5) ​ — ​ Decommissioning and other ​ ​ — ​ ​ 1.8 ​ ​ (1.8) ​ ​ — ​ Total ​ $ 13.3 ​ $ 3.7 ​ $ (6.4) ​ $ 10.6 ​ (1) Primarily includes payments made against the existing accrual, as well as immaterial impacts of foreign currency remeasurement.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss).
Components of AOCI, Net of Income Taxes	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cumulative Pension & Other ​ ​ ​ ​ ​ ​ ​ ​ Translation ​ Postretirement Benefit ​ ​ Cash Flow ​ ​ ​ ​ Three Months Ended March 31, 2023 and 2022 Adjustments Plans, Net ​ Hedges, Net Total Balance as of December 31, 2022 ​ $ (151.2) ​ $ 29.0 ​ $ (9.1) ​ $ (131.3) ​ Other comprehensive income (loss) ​ 10.5 ​ — ​ (13.2) ​ (2.7) ​ Amounts reclassified from AOCI to net income (1) ​ ​ — ​ ​ 0.3 ​ ​ 5.8 ​ ​ 6.1 ​ Balance as of March 31, 2023 ​ $ (140.7) ​ $ 29.3 ​ $ (16.5) ​ $ (127.9) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of December 31, 2021 ​ $ (114.3) ​ $ (33.6) ​ $ 0.7 ​ $ (147.2) ​ Other comprehensive income (loss) ​ (4.3) ​ — ​ 0.7 ​ (3.6) ​ Amounts reclassified from AOCI to net income (1) ​ ​ — ​ ​ 0.3 ​ ​ 0.8 ​ ​ 1.1 ​ Balance as of March 31, 2022 ​ $ (118.6) ​ $ (33.3) ​ $ 2.2 ​ $ (149.7) ​ ​ (1) The following is a summary of amounts reclassified from AOCI to net income (loss) for the three months ended March 31, 2023 and 2022: ​
Summary of amounts reclassified from AOCI to net income (loss)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ ​ ​ March 31, ​ Statements of Operations ​ AOCI Components 2023 2022 Classification ​ Cash flow hedging items ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity cash flow hedges ​ $ 6.4 ​ $ — ​ Cost of sales ​ Interest rate swaps ​ ​ — ​ ​ 0.8 ​ Interest expense, net ​ Total before tax ​ ​ 6.4 ​ ​ 0.8 ​ ​ ​ Tax effect ​ ​ (0.6) ​ ​ — ​ Provision for (benefit from) income taxes ​ Total, net of tax ​ $ 5.8 ​ $ 0.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortization of pension and other postretirement benefit plan items ​ ​ ​ ​ ​ ​ ​ ​ ​ Prior service cost (credit) ​ $ 0.1 ​ $ (0.1) ​ (a) ​ Net actuarial loss ​ ​ 0.3 ​ ​ 0.6 ​ (a) ​ Total before tax ​ ​ 0.4 ​ ​ 0.5 ​ ​ ​ Tax effect ​ ​ (0.1) ​ ​ (0.2) ​ Provision for (benefit from) income taxes ​ Total, net of tax ​ $ 0.3 ​ $ 0.3 ​ ​ ​ (a) These AOCI components are included in the computation of net periodic benefit costs (see Note 14).

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2023
Earnings Per Share
Schedule of Earnings per Share Basic and Diluted	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ (in millions, except per share data) 2023 2022 Earnings: ​ ​ ​ ​ ​ ​ ​ Net income (loss) from continuing operations ​ $ (48.9) ​ $ 17.1 ​ Net loss from discontinued operations ​ ​ — ​ ​ (0.4) ​ Net income (loss) ​ $ (48.9) ​ $ 16.7 ​ Shares: ​ ​ ​ ​ ​ ​ ​ Weighted average ordinary shares outstanding ​ 35.0 ​ 37.3 ​ Dilutive effect of RSUs, option awards, and PSUs (1) ​ — ​ 0.8 ​ Diluted weighted average ordinary shares outstanding ​ 35.0 ​ 38.1 ​ Income (loss) per share: ​ ​ ​ ​ ​ ​ ​ Income (loss) per share—basic: ​ ​ ​ ​ ​ ​ ​ Continuing operations ​ $ (1.40) ​ $ 0.46 ​ Discontinued operations ​ ​ — ​ ​ (0.01) ​ Income (loss) per share—basic ​ $ (1.40) ​ $ 0.45 ​ Income (loss) per share—diluted: ​ ​ ​ ​ ​ ​ ​ Continuing operations ​ $ (1.40) ​ $ 0.45 ​ Discontinued operations ​ ​ — ​ ​ (0.01) ​ Income (loss) per share—diluted ​ $ (1.40) ​ $ 0.44 ​ (1) Refer to Note 15 for discussion of RSUs, option awards, and PSUs granted to certain Company directors and employees. As the Company recorded a net loss from continuing operations for the three months ended March 31, 2023, potential shares related to equity-based awards have been excluded from the calculation of diluted EPS, as doing so would be anti-dilutive. There were 0.9 million anti-dilutive shares that have been excluded from the computation of diluted earnings per share for the three months ended March 31, 2022.

Impairment and Other Charges (T

Impairment and Other Charges (Tables)	3 Months Ended
	Mar. 31, 2023
Impairment and Other Charges.
Schedule of Other Charges	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2023 2022 Asset impairment charges or write-offs (Note 11) ​ $ 0.3 ​ $ 0.7 ​ European Commission request for information (Note 13) ​ ​ — ​ ​ 35.6 ​ Total ​ $ 0.3 ​ $ 36.3 ​

Acquisitions - Heathland B.V (D

Acquisitions - Heathland B.V (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended
	Jan. 03, 2022	Feb. 28, 2023	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Business Acquisition [Line Items]
Cash acquired from acquisition			$ 0	$ 1
Contingent consideration payment			1.2
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill			$ 414.2		$ 410.4
Heathland B.V.
Business Acquisition [Line Items]
Contingent payments to be paid	$ 6.4
Consideration paid upon signing the agreement				$ 22.9
Contingent consideration payment		$ 1.2
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Purchase price consideration	29.3
Heathland B.V. | Maximum
Business Acquisition [Line Items]
Consideration paid upon signing the agreement	$ 6.8

Divestitures and Discontinued_3

Divestitures and Discontinued Operations (Details) - Emulsion Polymers, Synthetic Rubber - Disposal Group, Disposed of by Sale, Not Discontinued Operations $ in Millions	Dec. 01, 2021 USD ($)
Disclosures by disposal group
Consideration	$ 402.4
Pension and other postretirement benefits	41.6
Working capital target	$ 47

Divestitures and Discontinued_4

Divestitures and Discontinued Operations - Results (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Net sales		$ 0.1
Cost of sales		0.7
Gross loss		(0.6)
Selling, general and administrative expenses		(0.2)
Operating loss		(0.4)
Loss from discontinued operations before income taxes		(0.4)
Net loss from discontinued operations		$ (0.4)
Emulsion Polymers, Synthetic Rubber | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Net sales related to supply agreement	$ 13.5
Cost of sales related to supply agreement	$ 15.4

Net Sales (Details)

Net Sales (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Net sales	$ 996.3	$ 1,386.7
Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales	206.2	295.2
Latex Binders
Disaggregation of Revenue [Line Items]
Net sales	248.1	306.7
Base Plastics
Disaggregation of Revenue [Line Items]
Net sales	289.9	396.5
Polystyrene
Disaggregation of Revenue [Line Items]
Net sales	209.1	318
Feedstocks
Disaggregation of Revenue [Line Items]
Net sales	43	70.3
United States
Disaggregation of Revenue [Line Items]
Net sales	250.8	309
United States | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales	110.9	138.4
United States | Latex Binders
Disaggregation of Revenue [Line Items]
Net sales	67.6	82.2
United States | Base Plastics
Disaggregation of Revenue [Line Items]
Net sales	68.7	84.5
United States | Feedstocks
Disaggregation of Revenue [Line Items]
Net sales	3.6	3.9
Europe
Disaggregation of Revenue [Line Items]
Net sales	544.8	797.2
Europe | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales	73.5	118.7
Europe | Latex Binders
Disaggregation of Revenue [Line Items]
Net sales	128.1	150.9
Europe | Base Plastics
Disaggregation of Revenue [Line Items]
Net sales	165.3	246.6
Europe | Polystyrene
Disaggregation of Revenue [Line Items]
Net sales	138.5	214.6
Europe | Feedstocks
Disaggregation of Revenue [Line Items]
Net sales	39.4	66.4
Asia-Pacific
Disaggregation of Revenue [Line Items]
Net sales	168	247.6
Asia-Pacific | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales	18.9	35.3
Asia-Pacific | Latex Binders
Disaggregation of Revenue [Line Items]
Net sales	50.7	71.7
Asia-Pacific | Base Plastics
Disaggregation of Revenue [Line Items]
Net sales	27.8	37.2
Asia-Pacific | Polystyrene
Disaggregation of Revenue [Line Items]
Net sales	70.6	103.4
Rest of World
Disaggregation of Revenue [Line Items]
Net sales	32.7	32.9
Rest of World | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales	2.9	2.8
Rest of World | Latex Binders
Disaggregation of Revenue [Line Items]
Net sales	1.7	1.9
Rest of World | Base Plastics
Disaggregation of Revenue [Line Items]
Net sales	$ 28.1	$ 28.2

Investments in Unconsolidated_3

Investments in Unconsolidated Affiliates (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) item	Mar. 31, 2022 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of joint ventures | item	1
Summarized Financial Information, Net Income
Gross profit	$ 37.2	$ 176
Net income (loss)	(48.9)	16.7
AmSty
Summarized Financial Information, Net Income
Sales	443.3	524.4
Gross profit	52.9	48.1
Net income (loss)	$ 37.8	$ 36.1

Investments in Unconsolidated_4

Investments in Unconsolidated Affiliates - Americas Styrenics (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Investments in Unconsolidated Affiliates
Investments in unconsolidated affiliates	$ 252.7		$ 255.1
AmSty
Investments in Unconsolidated Affiliates
Investments in unconsolidated affiliates	$ 252.7		$ 255.1
Percentage of ownership underlying net assets	50%		50%
Amortized weighted average remaining useful life	P1Y9M18D
Dividends received from operating activities	$ 20	$ 7.5
Unconsolidated affiliates
Investments in Unconsolidated Affiliates
Investment in unconsolidated affiliates-difference between carrying amount and underlying equity	$ 7		$ 8.4

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Inventories
Finished goods	$ 195.3	$ 218.4
Raw materials and semi-finished goods	265.9	295.6
Supplies	41.4	39.6
Total	$ 502.6	$ 553.6

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) € in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Feb. 26, 2020 USD ($)	Feb. 26, 2020 EUR (€)	Sep. 01, 2017 USD ($)
Debt Instruments
Carrying amount	$ 2,350.6	$ 2,353.7
Unamortized deferred financing fees	(34.1)	(36.1)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent	2,316.5	2,317.6
Less: current portion	(16.6)	(16)
Total long-term debt, net of unamortized deferred financing fees	2,299.9	2,301.6
Letter of Credit [Member]
Debt Instruments
Line of credit	22
Term Loan B
Debt Instruments
Less: current portion	$ (14.5)	(14.5)
2024 Term Loan B
Debt Instruments
Interest rate at end of period (as a percent)	6.84%
Carrying amount	$ 661.7	663.4
Unamortized deferred financing fees	(4.4)	(5.1)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent	$ 657.3	658.3
2028 Term Loan B
Debt Instruments
Interest rate at end of period (as a percent)	7.34%
Carrying amount	$ 734.1	735.9
Unamortized deferred financing fees	(13.8)	(14.4)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent	720.3	721.5
2026 Revolving Facility
Debt Instruments
Funds available for borrowings	100.5
Letters of credit, amount outstanding	$ 12
Commitment fee (as a percent)	0.375%
Maximum borrowing capacity	$ 375
Percentage of Revolving Facility borrowing capacity covenant trigger	30%
Net leverage ratio	4.85
2026 Revolving Facility | Maximum
Debt Instruments
Net leverage ratio	3.50
2029 Senior Notes
Debt Instruments
Interest rate	5.125%
Carrying amount	$ 447	447
Unamortized deferred financing fees	(12.5)	(12.9)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent	$ 434.5	434.1
2025 Senior Notes
Debt Instruments
Interest rate	5.375%		5.375%	5.375%	5.375%
Carrying amount	$ 500	500
Unamortized deferred financing fees	(3.4)	(3.7)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent	496.6	496.3	$ 500	€ 459.3	$ 500
Accounts Receivable Securitization Facility
Debt Instruments
Carrying amount	0	0
Unamortized deferred financing fees	0	0
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent	0	0
Maximum borrowing capacity	150
Accounts receivable available to support facility	150
Other Indebtedness
Debt Instruments
Carrying amount	7.8	7.4
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent	$ 7.8	$ 7.4

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Goodwill [Roll Forward]
Beginning Balance	$ 410.4
Foreign currency impact	3.8
Ending Balance	414.2	$ 410.4
Engineered Materials
Goodwill [Roll Forward]
Beginning Balance	348.9
Impairment losses	297.1	297.1
Foreign currency impact	2.6
Ending Balance	351.5	348.9
Latex Binders
Goodwill [Roll Forward]
Beginning Balance	14.8
Foreign currency impact	0.3
Ending Balance	15.1	14.8
Base Plastics
Goodwill [Roll Forward]
Beginning Balance	42.5
Foreign currency impact	0.8
Ending Balance	43.3	42.5
Polystyrene
Goodwill [Roll Forward]
Beginning Balance	4.2
Foreign currency impact	0.1
Ending Balance	$ 4.3	$ 4.2

Derivative Instruments (Details

Derivative Instruments (Details) MWh in Thousands, € in Millions, $ in Millions					3 Months Ended
	Apr. 07, 2022 USD ($)	Feb. 26, 2020 USD ($)	Sep. 06, 2017	Sep. 01, 2017 USD ($)	Mar. 31, 2023 USD ($) MWh item	Dec. 31, 2022 USD ($)	Feb. 26, 2020 EUR (€)	Sep. 01, 2017 EUR (€)
Derivative Instruments
Total debt					$ 2,316.5	$ 2,317.6
Foreign exchange forward contracts
Derivative Instruments
Derivative term					2 months
Foreign exchange forward contracts | Not Designated as Hedging Instruments
Derivative Instruments
Derivative contracts, notional amount					$ 657.5
Foreign exchange forward contracts | Designated as Hedging Instrument
Derivative Instruments
Number of subsidiaries participating | item					1
Foreign exchange forward contracts | Designated as Hedging Instrument | Cash Flow Hedges
Derivative Instruments
Amount hedged					$ 0
Cross currency swaps
Derivative Instruments
Derivative contracts, notional amount | €								€ 420
Derivative term		2 years 8 months 12 days		5 years
Cross currency swap weighted average interest rate (as a percent)		3.672%		3.45%
Cash proceeds	$ 1.9
Interest rate swaps
Derivative Instruments
Derivative contracts, notional amount					$ 200
Fixed interest rate per agreement (as a percent)					1.81%
Commodity Contract
Derivative Instruments
Derivative term					24 months
Number of megawatt hours of natural gas purchases | MWh					895
Commodity Contract | Cash Flow Hedges
Derivative Instruments
Derivative term					21 months
Number of megawatt hours of natural gas purchases | MWh					964
2025 Senior Notes
Derivative Instruments
Total debt		$ 500		$ 500	$ 496.6	496.3	€ 459.3
Interest rate		5.375%		5.375%	5.375%		5.375%	5.375%
2024 Term Loan B
Derivative Instruments
Total debt					$ 657.3	$ 658.3
Debt instrument, margin rate			2%
Variable rate floor (as a percent)			0%
Euro | Foreign exchange forward contracts | (Sell) | Not Designated as Hedging Instruments
Derivative Instruments
Derivative contracts, notional amount					520.9
Chinese Yuan | Foreign exchange forward contracts | (Sell) | Not Designated as Hedging Instruments
Derivative Instruments
Derivative contracts, notional amount					48.4
Swedish Krona | Foreign exchange forward contracts | Buy | Not Designated as Hedging Instruments
Derivative Instruments
Derivative contracts, notional amount					14.7
South Korean Won | Foreign exchange forward contracts | (Sell) | Not Designated as Hedging Instruments
Derivative Instruments
Derivative contracts, notional amount					21.8
New Taiwan Dollar | Foreign exchange forward contracts | (Sell) | Not Designated as Hedging Instruments
Derivative Instruments
Derivative contracts, notional amount					$ 19.6

Derivative Instruments - Income

Derivative Instruments - Income Statements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Cost of Sales	$ (959.1)	$ (1,210.7)
Interest expense, net	38.3	21.9
Other expense (income), net	(2.9)	3
Cost of Sales
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Cost of Sales	(959.1)	(1,210.7)
Amount of gain (loss) recognized in income, not designated	(12.4)
Interest Expense, Net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Interest expense, net	(38.3)	(21.9)
Other expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Other expense (income), net	2.9	(3)
Foreign exchange forward contracts | Not Designated as Hedging Instruments
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain (loss) recognized in income, not designated	(7.8)	8.8
Foreign exchange forward contracts | Not Designated as Hedging Instruments | Other expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain (loss) recognized in income, not designated	(7.8)	8.8
Cross currency swaps | Interest Expense, Net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain excluded from effectiveness testing		2.1
Interest rate swaps | Interest Expense, Net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of loss reclassified from AOCI into income, interest rate cash flow hedges		$ (0.8)
Commodity Contract | Cash Flow Hedges | Cost of Sales
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain reclassified from AOCI into income, commodity cash flow hedges	$ (6.4)

Derivative Instruments - Effect

Derivative Instruments - Effect on AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Derivative Instruments
Gain (Loss) Recognized in AOCI, Cash flow hedges	$ (9.9)	$ 1.5
Gain (Loss) Recognized in AOCI, Net investment hedges		6.1
Commodity Contract
Derivative Instruments
Gain (Loss) Recognized in AOCI, Cash flow hedges	$ (9.9)
Interest rate swaps
Derivative Instruments
Gain (Loss) Recognized in AOCI, Cash flow hedges		1.5
Cross currency swaps
Derivative Instruments
Gain (Loss) Recognized in AOCI, Net investment hedges		$ 6.1

Derivative Instruments - Gains

Derivative Instruments - Gains and Losses in Other expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Foreign exchange transaction gains (losses)	$ 10.5	$ (10.2)
Derivative, Gain (Loss) on Derivative, Net, Total	$ 2.7	$ (1.4)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Reclassification expected during next 12 months	$ 23
Foreign exchange forward contracts | Not Designated as Hedging Instruments
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain (loss) recognized in income, not designated	(7.8)	$ 8.8
Foreign exchange forward contracts | Not Designated as Hedging Instruments | Other expense, net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Amount of gain (loss) recognized in income, not designated	$ (7.8)	$ 8.8

Derivative Instruments - Financ

Derivative Instruments - Financial Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Derivatives, Financial Assets and Liabilities
Gross derivative asset position	$ 0.2	$ 0.2
Counterparty netting, derivative assets		(0.1)
Net derivative asset position		0.1
Liabilities at fair value	$ (49.1)	$ (27.7)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Gross derivative liability position	$ (53.5)	$ (29.9)
Counterparty netting, derivative liabilities	0.2	0.1
Net derivative liability position	(53.3)	(29.8)
Total net derivative position	(53.3)	(29.7)
Other noncurrent obligations.
Derivatives, Financial Assets and Liabilities
Liabilities at fair value	$ (4.4)	$ (2.2)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Accounts Receivable
Derivatives, Financial Assets and Liabilities
Gross derivative asset position	$ 0.2	$ 0.2
Counterparty netting, derivative assets	(0.2)
Foreign exchange forward contracts | Not Designated as Hedging Instruments
Derivatives, Financial Assets and Liabilities
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Accounts and Other Receivables, Net, Current
Gross derivative asset position	0.1	$ 0.2
Counterparty netting, derivative assets		(0.1)
Net derivative asset position		0.1
Liabilities at fair value	$ (12.5)	$ (11.1)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Gross derivative liability position	$ (12.5)	$ (11.1)
Counterparty netting, derivative liabilities	0.1	0.1
Net derivative liability position	(12.4)	(11)
Total net derivative position	(12.4)	(10.9)
Foreign exchange forward contracts | Not Designated as Hedging Instruments | Accounts Receivable
Derivatives, Financial Assets and Liabilities
Gross derivative asset position	0.1	0.2
Counterparty netting, derivative assets	(0.1)
Commodity Contract
Derivatives, Financial Assets and Liabilities
Liabilities at fair value	(13.5)	(5.3)
Gross derivative liability position	(15.4)	(6.6)
Net derivative liability position	(15.4)	(6.6)
Total net derivative position	(15.4)	(6.6)
Commodity Contract | Other noncurrent obligations.
Derivatives, Financial Assets and Liabilities
Liabilities at fair value	$ (1.9)	$ (1.3)
Commodity Contract | Not Designated as Hedging Instruments
Derivatives, Financial Assets and Liabilities
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current	Accounts Payable, Current
Commodity Contract | Cash Flow Hedges
Derivatives, Financial Assets and Liabilities
Gross derivative asset position	$ 0.1
Liabilities at fair value	(23.1)	$ (11.3)
Gross derivative liability position	(25.6)	(12.2)
Counterparty netting, derivative liabilities	0.1
Net derivative liability position	(25.5)	(12.2)
Total net derivative position	(25.5)	(12.2)
Commodity Contract | Cash Flow Hedges | Other noncurrent obligations.
Derivatives, Financial Assets and Liabilities
Liabilities at fair value	(2.5)	$ (0.9)
Commodity Contract | Cash Flow Hedges | Accounts Receivable
Derivatives, Financial Assets and Liabilities
Gross derivative asset position	0.1
Counterparty netting, derivative assets	$ (0.1)
Commodity Contract | Cash Flow Hedges | Not Designated as Hedging Instruments
Derivatives, Financial Assets and Liabilities
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Accounts Payable, Current

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities at Fair Value, Recurring (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Fair Value Measurements
Liabilities at fair value	$ (49.1)		$ (27.7)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current		Accounts Payable, Current
Total net derivative position	$ (53.3)		$ (29.7)
Impairment loss on assets	$ 0.3	$ 0.7
Impairment, Long-Lived Asset, Held-for-Use, Statement of Income or Comprehensive Income [Extensible Enumeration]	Impairment And Other charges
Boehlen Location
Fair Value Measurements
Impairment loss on assets	$ 0.3
Property Plant And Equipment At Fair Value | Boehlen Location
Fair Value Measurements
Assets at fair value, nonrecurring	3.2		3.2
Commodity Contract
Fair Value Measurements
Liabilities at fair value	(13.5)		(5.3)
Total net derivative position	(15.4)		(6.6)
Commodity Contract | Cash Flow Hedges
Fair Value Measurements
Liabilities at fair value	(23.1)		(11.3)
Total net derivative position	(25.5)		$ (12.2)
Not Designated as Hedging Instruments | Foreign exchange forward contracts
Fair Value Measurements
Derivative Asset, Statement of Financial Position [Extensible Enumeration]			Accounts and Other Receivables, Net, Current
Liabilities at fair value	$ (12.5)		$ (11.1)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current		Accounts Payable, Current
Total net derivative position	$ (12.4)		$ (10.9)
Not Designated as Hedging Instruments | Commodity Contract
Fair Value Measurements
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Accounts Payable, Current		Accounts Payable, Current
Not Designated as Hedging Instruments | Commodity Contract | Cash Flow Hedges
Fair Value Measurements
Derivative Liability, Statement of Financial Position [Extensible Enumeration]			Accounts Payable, Current
Recurring
Fair Value Measurements
Total net derivative position	$ (53.3)		$ (29.7)
Recurring | Level 2
Fair Value Measurements
Total net derivative position	(53.3)		(29.7)
Recurring | Not Designated as Hedging Instruments | Foreign exchange forward contracts
Fair Value Measurements
Assets at fair value			0.1
Liabilities at fair value	(12.4)		(11)
Recurring | Not Designated as Hedging Instruments | Commodity Contract
Fair Value Measurements
Liabilities at fair value	(15.4)		(6.6)
Recurring | Not Designated as Hedging Instruments | Commodity Contract | Cash Flow Hedges
Fair Value Measurements
Liabilities at fair value	(25.5)		(12.2)
Recurring | Not Designated as Hedging Instruments | Level 2 | Foreign exchange forward contracts
Fair Value Measurements
Assets at fair value			0.1
Liabilities at fair value	(12.4)		(11)
Recurring | Not Designated as Hedging Instruments | Level 2 | Commodity Contract
Fair Value Measurements
Liabilities at fair value	(15.4)		(6.6)
Recurring | Not Designated as Hedging Instruments | Level 2 | Commodity Contract | Cash Flow Hedges
Fair Value Measurements
Liabilities at fair value	$ (25.5)		(12.2)
Nonrecurring
Fair Value Measurements
Assets at fair value, nonrecurring			0
Liabilities at fair value, nonrecurring			$ 0

Fair Value Measurements - Items

Fair Value Measurements - Items not at Fair Value (Details) - Level 2 - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Fair Value of Debt Instruments
Total fair value of long term debt	$ 1,991.8	$ 2,041.9
2029 Senior Notes
Fair Value of Debt Instruments
Total fair value of long term debt	269.1	292.3
2028 Term Loan B
Fair Value of Debt Instruments
Total fair value of long term debt	662.1	687.1
2025 Senior Notes
Fair Value of Debt Instruments
Total fair value of long term debt	406.8	416.9
2024 Term Loan B
Fair Value of Debt Instruments
Total fair value of long term debt	$ 653.8	$ 645.6

Provision For Income Taxes (Det

Provision For Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Provision For Income Taxes
Effective tax rate	25.40%	56.90%
Tax benefits		$ 0
Provision for (benefit from) income taxes	$ (16.7)	22.6
Change in valuation allowances		$ 35.6

Commitments and Contingencies_2

Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2023 USD ($) item	Dec. 31, 2022 USD ($)
Commitments and Contingencies.
Accrued obligations for environmental remediation and restoration costs | $	$ 3.5	$ 3.5
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities and Other Liabilities, Other Liabilities, Noncurrent	Accrued Liabilities and Other Liabilities, Other Liabilities, Noncurrent
Environmental claims asserted | item	0

Commitments and Contingencies -

Commitments and Contingencies - Purchase Commitments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Nov. 30, 2022
Loss Contingencies [Line Items]
European Commission investigation		$ 35.6
Estimated Liability relating to European Commission Request for Information			$ 33.8
Maximum
Loss Contingencies [Line Items]
Purchase commitment period	4 years
Minimum
Loss Contingencies [Line Items]
Purchase commitment period	1 year

Commitments and Contingencies_3

Commitments and Contingencies - Change in asset retirement obligation (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
Change in asset retirement obligation
Balance at beginning of period	$ 35.8
Obligations incurred	0.9
Settlements	(2.2)
Accretion expense	0.5
Currency translation adjustment	0.6
Balance at end of period	$ 35.6

Commitments and Contingencies_4

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	May 31, 2021
Loss Contingencies [Line Items]
Current portion	$ 24.6	$ 25.3
Long-term portion	$ 11	$ 10.5
Pending Litigation | Synthos
Loss Contingencies [Line Items]
Current portion			$ 491

Pension Plans and Other Postr_3

Pension Plans and Other Postretirement Benefits - Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
U.S. Plans And Non-U.S. Plans
Net periodic benefit cost
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Pension plans | Non-U.S. Plans
Net periodic benefit cost
Service cost	$ 2	$ 3.2
Interest cost	1.7	0.7
Expected return on plan assets	(0.2)	(0.1)
Amortization of prior service cost	(0.1)	(0.1)
Amortization of net (gain) loss	(0.8)	0.7
Net periodic benefit cost	2.6	4.4
Pension plans | United States
Net periodic benefit cost
Service cost	0.1	0.2
Interest cost	0.2	0.2
Expected return on plan assets	(0.1)	(0.2)
Net periodic benefit cost	0.2	0.2
Other Postretirement Benefit Plans | Maximum
Net periodic benefit cost
Net periodic benefit cost	$ 0.2	$ 0.2

Pension Plans and Other Postr_4

Pension Plans and Other Postretirement Benefits - Net Amounts Recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Net amounts recognized in the balance sheets at December 31
Benefit obligations	$ 183.4	$ 177.8
Cash contributions and benefit payments to unfunded plans	1.7
Additional cash contributions, including benefit payments to unfunded plans	$ 11.4

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 8.2	$ 8.3
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	4.8	4.6
Unrecognized compensation cost	$ 13.5
Weighted-average period of recognition	2 years
Option Awards
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 2.6	3
Unrecognized compensation cost, options	$ 3.9
Weighted-average period of recognition	1 year 7 months 6 days
Performance Share Units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 0.8	$ 0.7
Unrecognized compensation cost	$ 7.4
Weighted-average period of recognition	2 years 4 months 24 days

Share-Based Compensation - RSUs

Share-Based Compensation - RSUs (Details) - Restricted Stock Units	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Other-than-Options, Shares Activity
Granted, Shares | shares	394,292
Other-than-Options, FV Activity
Granted, Weighted-Average Grant Date Fair Value per Share | $ / shares	$ 24.10

Share-Based Compensation - RSU

Share-Based Compensation - RSU Options and PSUs (Details)	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Restricted Stock Units
Other-than-Options, Shares Activity
Granted, Shares | shares	394,292
Other-than-Options, FV Activity
Granted, Weighted-Average Grant Date Fair Value per Share	$ 24.10
Option Awards
Options Outstanding Roll Forward
Granted, Options | shares	438,727
Fair Value Assumptions
Expected term (in years)	5 years 6 months
Expected volatility	54.01%
Risk-free interest rate	4.06%
Dividend yield	2%
Options granted, Weighted average grant date fair value	$ 10.86
Performance Share Units
Fair Value Assumptions
Expected term (in years)	3 years
Expected volatility	62.60%
Risk-free interest rate	4.41%
Share Price	$ 24.08
Other-than-Options, Shares Activity
Granted, Shares | shares	219,238
Other-than-Options, FV Activity
Granted, Weighted-Average Grant Date Fair Value per Share	$ 20.23

Segments - Reconciliation of Se

Segments - Reconciliation of Segment Reporting to Consolidated (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) segment	Mar. 31, 2022 USD ($)	Dec. 31, 2022
Segment Reporting Information [Line Items]
Number of operating segments | segment	6
Adjusted EBITDA	$ 62.4	$ 204.5
Depreciation and amortization	56	53
Engineered Materials
Segment Reporting Information [Line Items]
Adjusted EBITDA	(11.7)	34.7
Latex Binders
Segment Reporting Information [Line Items]
Adjusted EBITDA	26	30.2
Base Plastics
Segment Reporting Information [Line Items]
Adjusted EBITDA	25.6	68.6
Polystyrene
Segment Reporting Information [Line Items]
Adjusted EBITDA	15.7	45.3
Feedstocks
Segment Reporting Information [Line Items]
Adjusted EBITDA	(10.8)	4.1
Americas Styrenics
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 17.6	$ 21.6
AmSty
Segment Reporting Information [Line Items]
Percentage of ownership underlying net assets	50%		50%
AmSty | Americas Styrenics
Segment Reporting Information [Line Items]
Percentage of ownership underlying net assets	50%

Segments - Reconciliation of Ne

Segments - Reconciliation of Net Income to Segment Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Income (loss) from continuing operations before income taxes	$ (65.6)	$ 39.7
Interest expense, net	(38.3)	(21.9)
Depreciation and amortization	56	53
Corporate Unallocated	26.1	26.9
Adjusted EBITDA addbacks	7.6	63
Adjusted EBITDA	62.4	204.5
Net gain on disposition of businesses and assets		(0.3)
Restructuring and other charges	3.7	0.4
Acquisition transactions and integration net costs (benefit)		3.2
Asset impairment charges or write-offs	0.3	0.7
European Commission Request for Information (Note 16)		35.6
Other items	3.6	23.4
Corporate Unallocated
Segment Reporting Information [Line Items]
Interest expense, net	$ 38.3	$ 21.9

Restructuring (Details)

Restructuring (Details) - USD ($) $ in Millions		3 Months Ended
	Apr. 04, 2023	Mar. 31, 2023	Mar. 31, 2022
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 7.7	$ 0.4
Restructuring, Incurred Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]		Selling, General and Administrative Expense	Selling, General and Administrative Expense
Restructuring Reserve [Roll Forward]
Accrued charges/Balance at beginning of period		$ 13.3
Expenses		3.7
Deductions		(6.4)
Accrued charges/Balance at end of period		10.6
MEXICO
Restructuring Cost and Reserve [Line Items]
Proceeds received on sale of property	$ 19
Transformational Restructuring Program
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 0.3
Cumulative life-to-date charges		8.8
Other Restructurings
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			0.1
Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost		4
Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		(0.6)
Restructuring Reserve [Roll Forward]
Accrued charges/Balance at beginning of period		13.3
Expenses		(0.6)
Deductions		(2.1)
Accrued charges/Balance at end of period		10.6
Employee termination benefits | Transformational Restructuring Program
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 0.3
Cumulative life-to-date charges		8.8
Employee termination benefits | Transformational Restructuring Program | Maximum
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges		1
Contract Termination Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		2.5
Expected restructuring charges		17.6
Restructuring Reserve [Roll Forward]
Expenses		2.5
Deductions		(2.5)
Decommissioning and other
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		1.8
Expected restructuring charges		2.2
Restructuring Reserve [Roll Forward]
Expenses		1.8
Deductions		(1.8)
Plastic Solution
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges		1.2
Plastic Solution | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Cumulative life-to-date charges		1.4
Plastic Solution | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		(0.4)
Cumulative life-to-date charges		3
Plastic Solution | Decommissioning and other
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.7
Cumulative life-to-date charges		0.7
Feedstocks
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges		18.6
Feedstocks | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.9
Cumulative life-to-date charges		36
Feedstocks | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		(0.2)
Cumulative life-to-date charges		3.7
Feedstocks | Contract Termination Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		2.5
Cumulative life-to-date charges		2.9
Feedstocks | Decommissioning and other
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.5
Cumulative life-to-date charges		3.7
Engineered Materials
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		7.7
Cumulative life-to-date charges		64.4
Engineered Materials | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		3.1
Cumulative life-to-date charges		6.3
Engineered Materials | Employee termination benefits
Restructuring Cost and Reserve [Line Items]
Cumulative life-to-date charges		2.4
Engineered Materials | Decommissioning and other
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.6
Cumulative life-to-date charges		$ 4.3

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Components (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	$ 420.3	$ 1,013.1
Balance at end of period	376.2	972.8
Cumulative Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(151.2)	(114.3)
Other comprehensive income (loss)	10.5	(4.3)
Balance at end of period	(140.7)	(118.6)
Pension & Other Postretirement Benefit Plans, Net
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	29	(33.6)
Amounts reclassified from AOCI to net income	0.3	0.3
Balance at end of period	29.3	(33.3)
Cash Flow Hedges, Net
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(9.1)	0.7
Other comprehensive income (loss)	(13.2)	0.7
Amounts reclassified from AOCI to net income	5.8	0.8
Balance at end of period	(16.5)	2.2
Accumulated other comprehensive income(Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(131.3)	(147.2)
Other comprehensive income (loss)	(2.7)	(3.6)
Amounts reclassified from AOCI to net income	6.1	1.1
Balance at end of period	$ (127.9)	$ (149.7)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Reclassification (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	$ 959.1	$ 1,210.7
Interest expense, net	38.3	21.9
Income before income taxes	65.6	(39.7)
Provision for income taxes	(16.7)	22.6
Net income	48.9	(16.7)
Pension & Other Postretirement Benefit Plans, Net | Reclassified from AOCI to net income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	0.4	0.5
Provision for income taxes	(0.1)	(0.2)
Net income	$ 0.3	$ 0.3
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] | Reclassified from AOCI to net income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credit	$ 0.1	$ (0.1)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] | Reclassified from AOCI to net income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net actuarial loss	$ 0.3	$ 0.6
Cash Flow Hedges, Net | Reclassified from AOCI to net income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net		0.8
Income before income taxes	6.4	0.8
Provision for income taxes	(0.6)
Net income	5.8	$ 0.8
Cash Flow Hedges, Net | Reclassified from AOCI to net income (loss) | Commodity Contract
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	$ 6.4

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings:
Net income (loss) from continuing operations	$ (48.9)	$ 17.1
Net loss from discontinued operations, net of income taxes		(0.4)
Net income (loss)	$ (48.9)	$ 16.7
Shares:
Weighted average ordinary shares outstanding	35	37.3
Dilutive effect of RSUs, option awards and PSUs		0.8
Diluted weighted average ordinary shares outstanding	35	38.1
Income (loss) per share
Income (loss) per share-basic, Continuing operations	$ (1.40)	$ 0.46
Income (loss) per share-basic, Discontinued operations		(0.01)
Income (loss) per share-basic	(1.40)	0.45
Income (loss) per share-diluted, Continuing operations	(1.40)	0.45
Income (loss) per share-diluted, Discontinued operations		(0.01)
Income (loss) per share- diluted	$ (1.40)	$ 0.44
Anti-dilutive shares excluded		0.9

Impairment and Other Charges (D

Impairment and Other Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Impairment and Other Charges.
Asset impairment charges or write-offs (Note 11)	$ 0.3	$ 0.7
European Commission request for information (Note 13)		35.6
Total	$ 0.3	$ 36.3