Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2018	May 01, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Entity Registrant Name	Trinseo S.A.
Entity Central Index Key	0001519061
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		43,177,966

Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 398.9	$ 432.8
Accounts receivable, net of allowance for doubtful accounts (March 31, 2018: $5.1; December 31, 2017: $5.6)	728.7	685.5
Inventories	588.3	510.4
Other current assets	18.7	17.5
Total current assets	1,734.6	1,646.2
Investments in unconsolidated affiliates	168.1	152.5
Property, plant and equipment, net of accumulated depreciation (March 31, 2018: $556.5; December 31, 2017: $523.7)	635.2	627.0
Other assets
Goodwill	74.2	72.5
Other intangible assets, net	206.9	207.5
Deferred income tax assets	34.7	35.5
Deferred charges and other assets	32.7	30.8
Total other assets	348.5	346.3
Total assets	2,886.4	2,772.0
Current liabilities
Short-term borrowings and current portion of long-term debt	7.0	7.0
Accounts payable	454.2	436.8
Income taxes payable	36.9	35.9
Accrued expenses and other current liabilities	135.3	146.9
Total current liabilities	633.4	626.6
Noncurrent liabilities
Long-term debt, net of unamortized deferred financing fees	1,164.0	1,165.0
Deferred income tax liabilities	51.4	49.2
Other noncurrent obligations	281.9	256.4
Total noncurrent liabilities	1,497.3	1,470.6
Commitments and contingencies (Note 11)
Shareholders' equity
Ordinary shares, $0.01 nominal value, 50,000.0 shares authorized (March 31, 2018: 48.8 shares issued and 43.4 shares outstanding; December 31, 2017: 48.8 shares issued and 43.4 shares outstanding)	0.5	0.5
Additional paid-in-capital	566.6	578.8
Treasury shares, at cost (March 31, 2018: 5.4 shares; December 31, 2017: 5.4 shares)	(299.5)	(286.8)
Retained earnings	632.4	527.9
Accumulated other comprehensive loss	(144.3)	(145.6)
Total shareholders' equity	755.7	674.8
Total liabilities and shareholders' equity	$ 2,886.4	$ 2,772.0

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Consolidated Balance Sheets
Allowance for doubtful accounts	$ 5.1	$ 5.6
Accumulated depreciation	$ 556.5	$ 523.7
Ordinary shares, nominal value	$ 0.01	$ 0.01
Ordinary shares, shares authorized	50,000,000,000	50,000,000,000
Ordinary shares, shares issued	48,800,000	48,800,000
Ordinary shares, shares outstanding	43,400,000	43,400,000
Treasury stock, shares	5,400,000	5,400,000

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Consolidated Statements of Operations
Net sales	$ 1,121.6	$ 1,104.5
Cost of sales	946.4	905.5
Gross profit	175.2	199.0
Selling, general and administrative expenses	64.4	59.6
Equity in earnings of unconsolidated affiliates	45.5	19.3
Operating income	156.3	158.7
Interest expense, net	14.9	18.2
Other income, net	(3.8)	(6.1)
Income before income taxes	145.2	146.6
Provision for income taxes	24.9	29.3
Net income	$ 120.3	$ 117.3
Weighted average shares- basic	43.4	44.1
Net income per share- basic	$ 2.77	$ 2.66
Weighted average shares- diluted	44.4	45.3
Net income per share- diluted	$ 2.71	$ 2.59
Dividends on ordinary shares	$ 0.36	$ 0.30

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Consolidated Statements of Comprehensive Income (Loss)
Net income	$ 120.3	$ 117.3
Other comprehensive income (loss), net of tax
Cumulative translation adjustments	(2.1)	4.2
Net gain (loss) on cash flow hedges	2.8	(4.8)
Amounts reclassified from accumulated other comprehensive income (loss)	0.6	1.4
Total other comprehensive income (loss), net of tax	1.3	0.8
Comprehensive income	$ 121.6	$ 118.1

Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Ordinary Shares	Additional Paid-In Capital	Treasury Shares	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Total
Balance at beginning of period at Dec. 31, 2016	$ 0.5	$ 573.7	$ (217.5)	$ (170.2)	$ 261.2	$ 447.7
Balance at beginning of period, shares at Dec. 31, 2016	44.3		4.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					117.3	117.3
Other comprehensive income				0.8		0.8
Stock-based compensation		1.0	$ 6.9			7.9
Stock-based compensation, shares from treasury stock	0.2		(0.2)
Purchase of treasury shares			$ (23.3)			(23.3)
Purchase of treasury shares, shares	(0.4)		0.4
Dividends on ordinary shares					(13.7)	(13.7)
Balance at end of period at Mar. 31, 2017	$ 0.5	574.7	$ (233.9)	(169.4)	364.8	536.7
Balance at end of period, shares at Mar. 31, 2017	44.1		4.7
Balance at beginning of period at Dec. 31, 2017	$ 0.5	578.8	$ (286.8)	(145.6)	527.9	$ 674.8
Balance at beginning of period, shares at Dec. 31, 2017	43.4		5.4			43.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					120.3	$ 120.3
Other comprehensive income				1.3		1.3
Stock-based compensation		(12.2)	$ 11.5			(0.7)
Stock-based compensation, shares from treasury stock	0.3		(0.3)
Purchase of treasury shares			$ (24.2)			(24.2)
Purchase of treasury shares, shares	(0.3)		0.3
Dividends on ordinary shares					(15.8)	(15.8)
Balance at end of period at Mar. 31, 2018	$ 0.5	$ 566.6	$ (299.5)	$ (144.3)	$ 632.4	$ 755.7
Balance at end of period, shares at Mar. 31, 2018	43.4		5.4			43.4

Consolidate Statements of Shareholders' Equity (Parenthetical)) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Consolidated Statement of Stockholders' Equity
Dividends on ordinary shares	$ 0.36	$ 0.30

Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net income	$ 120.3	$ 117.3
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	31.9	24.7
Amortization of deferred financing fees and debt discounts	1.1	1.4
Deferred income tax	2.5	11.3
Stock-based compensation expense	5.5	4.7
Earnings of unconsolidated affiliates, net of dividends	(15.5)	(2.9)
Unrealized net losses (gains) on foreign exchange forward contracts	0.1	0.2
Gain on sale of businesses and other assets	(0.5)	(9.9)
Changes in assets and liabilities
Accounts receivable	(32.7)	(133.3)
Inventories	(70.3)	(91.6)
Accounts payable and other current liabilities	3.0	49.9
Income taxes payable	0.8	5.6
Other assets, net	(1.3)	(4.5)
Other liabilities, net	(4.1)	1.4
Cash provided by (used in) operating activities	40.8	(25.7)
Cash flows from investing activities
Capital expenditures	(30.6)	(36.0)
Proceeds from the sale of businesses and other assets	0.5	42.1
Distributions from unconsolidated affiliates		0.8
Cash provided by (used in) investing activities	(30.1)	6.9
Cash flows from financing activities
Short term borrowings, net	(0.1)	(0.1)
Purchase of treasury shares	(23.8)	(26.6)
Dividends paid	(16.2)	(13.3)
Proceeds from exercise of option awards	1.9	3.4
Withholding taxes paid on restricted share units	(8.0)	(0.1)
Cash used in financing activities	(48.0)	(38.0)
Effect of exchange rates on cash	3.4	1.8
Net change in cash and cash equivalents	(33.9)	(55.0)
Cash and cash equivalents, beginning of period	432.8	465.1
Cash and cash equivalents, end of period	398.9	410.1
2021 Term Loan B
Cash flows from financing activities
Repayments of Term Loans		$ (1.3)
2024 Term Loan B
Cash flows from financing activities
Repayments of Term Loans	$ (1.8)

Basis of Presentation	3 Months Ended
Basis of Presentation	Mar. 31, 2018
Basis of Presentation.
Basis of Presentation	NOTE 1—BASIS OF PRESENTATION The unaudited interim condensed consolidated financial statements of Trinseo S.A. and its subsidiaries (the “Company”) as of and for the periods ended March 31, 2018 and 2017 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 2017 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 March 1, 2018. The December 31, 2017 condensed consolidated balance sheet data presented herein was derived from the Company’s December 31, 2017 audited consolidated financial statements, but does not include all disclosures required by GAAP for annual periods. Certain prior year amounts have been reclassified to conform to the current period presentation. These reclassifications did not have a material impact on the Company’s financial position or results. Refer to Notes 2, 7, and 15 for further information.

Recent Accounting Guidance	3 Months Ended
Recent Accounting Guidance	Mar. 31, 2018
Recent Accounting Guidance
Recent Accounting Guidance	NOTE 2—RECENT ACCOUNTING GUIDANCE In May 2014, the Financial Accounting Standards Board (“FASB”) and the International Accounting Standards Board (“IASB”) jointly issued guidance (“Topic 606”) which clarifies the principles for recognizing revenue and develops a common revenue standard for GAAP and International Financial Reporting Standards (“IFRS”). The core principle of the guidance, which the FASB issued certain clarifying updates for, is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The Company adopted Topic 606 effective January 1, 2018, electing to apply the modified retrospective approach only to contracts that were not completed as of the date of initial application at the individual contract level, rather than applying the portfolio approach. Results for reporting periods beginning after January 1, 2018 are presented under Topic 606, while prior period amounts have not been adjusted and continue to be reported in accordance with historical accounting standards (“Topic 605”). As a result of our implementation procedures, we have determined that the cumulative effect to retained earnings from initially applying Topic 606 was immaterial and therefore, no adjustment was recorded. Furthermore, based on current contracts with customers, we do not expect the adoption of the new revenue standard to have a material impact to our financial statements on an ongoing basis. Refer to Note 3 for new disclosure requirements in effect as a result of this adoption. In February 2016, the FASB issued guidance related to leases that outlines a comprehensive lease accounting model and supersedes the current lease guidance. The new guidance requires lessees to recognize on the consolidated balance sheets lease liabilities and corresponding right-of-use assets for all leases with terms of greater than 12 months. It also changes the definition of a lease and expands the disclosure requirements of lease arrangements. This new guidance is effective for public companies for annual and interim periods beginning after December 15, 2018, with early adoption permitted. The new guidance must be adopted using a modified retrospective transition, and provides for certain practical expedients. The Company is in the process of assessing the impact on its consolidated financial statements from the adoption of the new guidance. However, as we are the lessee under various real estate, railcar, and other equipment leases, which we currently account for as operating leases, we anticipate an increase in the recognition of right-of-use assets and lease liabilities as a result of this adoption. In March 2017, the FASB issued guidance that requires employers to present the service cost component of net periodic benefit cost in the same statement of operations line item as other employee compensation costs arising from services rendered during the period. The other components of net periodic benefit cost are to be presented outside of any subtotal of operating income. This guidance also requires employers to prospectively only consider the service cost component of net periodic benefit cost for potential capitalization into assets, with all other components of net periodic benefit cost being ineligible for capitalization. The Company adopted this guidance effective January 1, 2018 on a retrospective basis. As a result of this adoption, for the three months ended March 31, 2017, the Company reclassified net periodic benefit cost of $1.2 million from “Cost of sales” and $0.8 million from “Selling, general and administrative expenses” to “Other income, net” within the condensed consolidated statements of operations. The change related to capitalization guidance is not expected to have a material impact on the Company’s consolidated financial statements. In August 2017, the FASB issued significant amendments to its existing hedge accounting guidance. Among other things, this guidance will make more financial and nonfinancial hedging strategies eligible for hedge accounting, amend presentation and disclosure requirements, and change how companies assess effectiveness. This guidance is required for public companies for annual and interim periods beginning after December 15, 2018, with early adoption permitted. The Company will adopt this guidance effective April 1, 2018, and is in the process of evaluating the ongoing impact to the Company’s consolidated financial statements. In February 2018, the FASB issued guidance to address certain stranded income tax effects in accumulated other comprehensive income/loss (“AOCI”) resulting from the enactment of the U.S. “Tax Cuts and Jobs Act” signed into law on December 22, 2017. The amendment provides financial statement preparers with an option to reclassify stranded tax effects within AOCI, resulting from the reduction of the U.S. federal corporate income tax rate, to retained earnings. The amendment also includes disclosure requirements regarding the Company’s accounting policy for releasing income tax effects from AOCI. The amendment is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2018. Early adoption is permitted, and the provisions of the amendment should be applied either in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act is recognized. While the Company is still evaluating the provisions of this amendment, should the Company choose to adopt this guidance, it is not expected to have a material impact on the Company’s consolidated financial statements.

Net Sales

3 Months Ended

Mar. 31, 2018

Revenue from Contract with Customer [Abstract]

Net Sales

NOTE 3 — NET SALES

As discussed in Note 2, effective January 1, 2018, the Company adopted accounting guidance, Topic 606, issued by the FASB related to the recognition of revenue from contracts with customers. The Company’s accounting policy and practical expedient elections related to revenue recognition, including those elected as a result of the adoption of Topic 606, are summarized as follows.

Sales are recognized at a point when control of the promised goods or services is transferred to the customer in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services, and when the Company’s related performance obligation is satisfied under the terms of the contract. Standard terms of delivery are included in contracts of sale, order confirmation documents, and invoices. Sales and other taxes that the Company collects concurrent with sales-producing activities are excluded from “Net sales” and included as a component of “Cost of sales” in the condensed consolidated statements of operations. Additionally, freight and any directly related costs of transporting finished products to customers are accounted for as fulfilment costs and are also included within “Cost of sales”. The amount of net sales recognized varies with changes in returns, rebates, cash sales incentives, and other allowances offered to customers based on the Company's experience.

The Company has elected to apply the following practical expedients as allowed under Topic 606:

·

The incremental costs of obtaining contracts are expensed as incurred if the amortization period of the assets that the Company otherwise would have recognized is one year or less, and are included within “Selling, general and administrative expenses” in the condensed consolidated statements of operations.

·

When the period between customer payment and transfer of goods/services is determined to be one year or less at contract inception, the promised amount of consideration under the contract is not adjusted for the effects of a significant financing component.

·

In consideration of the disclosure requirements regarding the transaction price and expected period of recognition of remaining performance obligations that are unsatisfied as of the end of a reporting period, the Company has elected the following optional exemptions:

o

The Company will not disclose the aggregate amount of the transaction price allocated to remaining performance obligations for its contracts with an original expected duration of one year or less, which applies to the vast majority of the Company’s contracts with customers.

o

For contracts with customers containing variable consideration (via enforceable minimum volume requirements) and an original expected duration greater than one year, the Company will not disclose the transaction price allocated to remaining performance obligations if the variable consideration is allocated entirely to a wholly unsatisfied performance obligation. Under these contracts with customers, each unit of production generally represents a separate performance obligation, the pricing for which is based on current or forecasted raw material prices, often using formulas that utilize commodity indices. Therefore, future volumes are wholly unsatisfied and disclosure of the transaction price allocated to remaining performance obligations is not required. The variable consideration in these contracts is resolved typically at the issuance of a purchase order or as of the date of revenue recognition.

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, 2018 and 2017, respectively:


	Three Months Ended
	March 31, 2018
	Latex		Synthetic		Performance
	Binders		Rubber		Plastics		Polystyrene		Feedstocks		Total
United States	$	64.3	$	—	$	84.1	$	0.2	$	3.7	$	152.3
Europe		113.3		149.2		249.2		148.2		57.9		717.8
Asia-Pacific		74.3		—		47.3		91.2		13.0		225.8
Rest of World		3.4		—		22.3		—		—		25.7
Total	$	255.3	$	149.2	$	402.9	$	239.6	$	74.6	$	1,121.6


	Three Months Ended
	March 31, 2017(1)
	Latex		Synthetic		Performance
	Binders		Rubber		Plastics		Polystyrene		Feedstocks		Total
United States	$	76.0	$	—	$	82.8	$	0.2	$	3.8	$	162.8
Europe		119.5		163.4		199.4		140.1		34.7		657.1
Asia-Pacific		89.0		—		32.7		88.1		48.4		258.2
Rest of World		4.4		—		22.0		—		—		26.4
Total	$	288.9	$	163.4	$	336.9	$	228.4	$	86.9	$	1,104.5

(1)

As the Company has adopted Topic 606 utilizing the modified retrospective approach, amounts for the three months ended March 31, 2017 above are disclosed as recognized under Topic 605.

For all material contracts with customers, control is transferred and sales are recognized at a point in time, when the Company satisfies the performance obligations according to the terms of the contract, and when title and the risk of loss is passed to the customer. Title and risk of loss varies by region and customer and is determined based upon the purchase order received from the customer and the applicable contractual terms or jurisdictional standards. The Company receives cash equal to the invoice price for most product sales, subject to cash sales incentives with certain customers, with payment terms generally ranging from 10 to 90 days (with an approximate weighted average of 50 days as of March 31, 2018), also varying by segment and region.

Certain of the Company’s contracts with customers contain multiple performance obligations, most commonly due to the sale of multiple distinct products. The transaction price within these contracts is allocated between these separate and distinct products based on their stand-alone selling prices, as defined within the contract. The Company’s products are typically sold at observable stand-alone sales values, which are used to determine the estimated stand-alone selling price. The stand-alone selling prices of the Company’s products are generally based, in part, on the current or forecasted costs of key raw materials, but are often subject to a predetermined lag period for the pass through of these costs. As such, contracts with customers typically include provisions that allow for the changes in stand-alone selling prices to reflect the pass through of changes in raw material costs, often using pricing formulas that utilize commodity indices.

In cases where the Company’s transaction price is considered variable at the point of revenue recognition, the ‘most likely amount’ method is used to estimate the effect of any related uncertainty. In formulating this estimate, the Company considers all historical, current, and forecasted information that is reasonably available to identify a reasonable number of possible consideration amounts. Once the transaction price, including impacts of variable consideration, is estimated, revenue is recognized only to the extent that it is probable that a subsequent change in the estimate would not result in a significant revenue reversal. Furthermore, if the Company is not able to rely on observable stand-alone selling prices, the ‘expected cost plus a margin approach’ is utilized to estimate the stand-alone selling price of each performance obligation, primarily utilizing historical experience. During the three months ended March 31, 2018, the impact of recognizing changes in selling prices related to prior periods was immaterial.

Investments in Unconsolidated Affiliates

3 Months Ended

Mar. 31, 2018

Investments in Unconsolidated Affiliates

Investments in Unconsolidated Affiliates

NOTE 4—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). Previously, the Company also had a 50% share in Sumika Styron Polycarbonate Limited (“Sumika Styron Polycarbonate”, a polycarbonate, or PC, joint venture with Sumitomo Chemical Company Limited), until the sale of the Company’s investment in the joint venture during the first quarter of 2017 (refer to discussion below for further information). Investments held in unconsolidated affiliates are accounted for by the equity method. The results of Americas Styrenics are included within its own reporting segment. The results of Sumika Styron Polycarbonate were included within the Performance Plastics reporting segment (as recast due to the segment realignment effective January 1, 2018 discussed further in Note 15) until the Company sold its share of the entity during the first quarter of 2017.

Both of the unconsolidated affiliates are privately held companies; therefore, quoted market prices for their stock are not available. The summarized financial information of the Company’s unconsolidated affiliates is shown below. This table includes summarized financial information for Sumika Styron Polycarbonate through the date of sale in January 2017.


	Three Months Ended
	March 31,
	2018		2017
Sales	$	486.6	$	433.9
Gross profit	$	95.2	$	20.6
Net income	$	85.7	$	6.3

Americas Styrenics

As of March 31, 2018 and December 31, 2017, respectively, the Company’s investment in Americas Styrenics was $168.1 million and $152.5 million, which was $43.8 million and $46.4 million less than the Company’s 50% share of the underlying net assets of Americas Styrenics. This amount represents the difference between the book value of assets contributed to the joint venture at the time of formation (May 1, 2008) and the Company’s 50% share of the total recorded value of the joint venture’s assets and certain adjustments to conform with the Company’s accounting policies. This difference is being amortized over a weighted average remaining useful life of the contributed assets of approximately 2.6 years as of March 31, 2018. The Company received dividends from Americas Styrenics of $30.0 million and $7.5 million during the three months ended March 31, 2018 and 2017, respectively.

Sumika Styron Polycarbonate

On January 31, 2017, the Company completed the sale of its 50% share in Sumika Styron Polycarbonate to Sumitomo Chemical Company Limited for total sales proceeds of approximately $42.1 million. As a result, the Company recorded a gain on sale of $9.3 million during the three months ended March 31, 2017, which was included within “Other income, net” in the condensed consolidated statement of operations and was allocated entirely to the Performance Plastics segment (as recast under the segment realignment discussed further in Note 15). In addition, the parties entered into a long-term agreement to continue sourcing PC resin from Sumika Styron Polycarbonate to the Company’s Performance Plastics segment.

Due to the sale in January 2017, the Company no longer had an investment in Sumika Styron Polycarbonate as of December 31, 2017. The Company received dividends from Sumika Styron Polycarbonate of $9.8 million during the three months ended March 31, 2017 related to the Company’s proportionate share of earnings from the year ended December 31, 2016.

Inventories

3 Months Ended

Mar. 31, 2018

Inventories

Inventories

NOTE 5—INVENTORIES

Inventories consisted of the following:


	March 31,		December 31,
	2018		2017
Finished goods	$	285.6	$	250.9
Raw materials and semi-finished goods		265.1		226.7
Supplies		37.6		32.8
Total	$	588.3	$	510.4

Debt

3 Months Ended

Mar. 31, 2018

Debt

Debt

NOTE 6—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, 2018 and December 31, 2017.

As of March 31, 2018 and December 31, 2017, debt consisted of the following:


			March 31, 2018						December 31, 2017
	Interest Rate as of March 31, 2018	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
2022 Revolving Facility(2)	Various	September 2022	$	—	$	—	$	—	$	—	$	—	$	—
2024 Term Loan B(3)	4.377%	September 2024		696.5		(17.8)		678.7		698.3		(18.3)		680.0
2025 Senior Notes	5.375%	September 2025		500.0		(9.1)		490.9		500.0		(9.4)		490.6
Accounts Receivable Securitization Facility(4)	Various	May 2019		—		—		—		—		—		—
Other indebtedness	Various	Various		1.4		—		1.4		1.4		—		1.4
Total debt			$	1,197.9	$	(26.9)	$	1,171.0	$	1,199.7	$	(27.7)	$	1,172.0
Less: current portion								(7.0)						(7.0)
Total long-term debt, net of unamortized deferred financing fees							$	1,164.0					$	1,165.0

(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)

Under the 2022 Revolving Facility, the Company had a capacity of $375.0 million and funds available for borrowing of $359.9 million (net of $15.1 million outstanding letters of credit) as of March 31, 2018. 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)

The 2024 Term Loan B bears an interest rate of LIBOR plus 2.50%, subject to a 0.00% LIBOR floor. As of March 31, 2018, $7.0 million of the scheduled future payments related to this facility were classified as current debt on the Company’s condensed consolidated balance sheet.

(4)

This facility had a borrowing capacity of $150.0 million as of March 31, 2018. Additionally, as of March 31, 2018, the Company had accounts receivable available to support this facility in excess of its borrowing capacity, based on the pool of eligible accounts receivable. In regard to outstanding borrowings, fixed interest charges are 1.95% plus variable commercial paper rates, while for available, but undrawn commitments, fixed interest charges are 1.0%.

.

Goodwill and Intangible Assets

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets.

Goodwill and Intangible Assets

NOTE 7—GOODWILL

The following table shows changes in the carrying amount of goodwill, by segment, from December 31, 2017 to March 31, 2018. Prior period balances in this table have been recast in conjunction with the segment realignment that occurred during the first quarter of 2018. Refer to Note 15 for further information.


	Latex		Synthetic		Performance						Americas
	Binders		Rubber		Plastics		Polystyrene		Feedstocks		Styrenics		Total
Balance at December 31, 2017	$	16.5	$	11.7	$	39.6	$	4.7	$	—	$	—	$	72.5
Foreign currency impact		0.4		0.3		0.9		0.1		—		—		1.7
Balance at March 31, 2018	$	16.9	$	12.0	$	40.5	$	4.8	$	—	$	—	$	74.2

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Derivative Instruments

3 Months Ended

Mar. 31, 2018

Derivative Instruments [Abstract]

Derivative Instruments

NOTE 8—DERIVATIVE INSTRUMENTS

The Company’s ongoing business operations expose it to various risks, including fluctuating foreign exchange rates and interest rate risk. To manage these risks, the Company periodically enters into derivative financial instruments, such as foreign exchange forward contracts and interest rate swap agreements. 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. Refer to Note 9 for fair value disclosures related to these instruments.

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 our 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, 2018, the Company had open foreign exchange forward contracts with a notional U.S. dollar equivalent absolute value of $334.7 million. The following table displays the notional amounts of the most significant net foreign exchange hedge positions outstanding as of March 31, 2018:


	March 31,
Buy / (Sell)	2018
Euro	$	(129.4)
Chinese Yuan	$	(78.2)
Swiss Franc	$	54.6
Taiwan Dollar	$	14.4
Indonesian Rupiah	$	(14.0)

Open foreign exchange forward contracts as of March 31, 2018 had maturities occurring over a period of two months.

Foreign Exchange Cash Flow Hedges

The Company also enters into forward contracts 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 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 foreign exchange cash flow hedges as of March 31, 2018 had maturities occurring over a period of nine months, and had a net notional U.S. dollar equivalent of $162.0 million.

Interest Rate Swaps

On September 6, 2017, the Company issued the 2024 Term Loan B, which bears an interest rate of LIBOR plus 2.50%, 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 the third quarter of 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.

As of March 31, 2018, the Company had open interest rate swap agreements with a net notional U.S. dollar equivalent of $200.0 million which had an effective date of September 29, 2017 and mature over a period of five years. Under the terms of the swap agreements, the Company is 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 (1.88% as of March 31, 2018) from the counterparties.

Net Investment Hedge

Through August 31, 2017, the Company had designated a portion (€280 million) of the original principal amount of the Company’s previous €375.0 million Euro Notes as a hedge of the foreign currency exposure of the Issuers’ net investment in certain European subsidiaries. Effective September 1, 2017, the Company de-designated the Euro Notes as a net investment hedge of the Issuers’ net investment in certain European subsidiaries, as the Euro Notes were redeemed on September 7, 2017. Through the date of de-designation, this hedge was deemed to be highly effective, and changes in the Euro Notes’ carrying value resulting from fluctuations in the euro exchange rate were recorded as cumulative foreign currency translation loss of $24.1 million within AOCI as of December 31, 2017.

On August 29, 2017, the Issuers executed an indenture pursuant to which they issued the $500.0 million 5.375% 2025 Senior Notes. Subsequently, on September 1, 2017, the Company entered into certain fixed-for-fixed cross currency swaps (“CCS”), swapping USD principal and interest payments on the newly issued 2025 Senior Notes for euro-denominated payments. Under the terms of the CCS, the Company has notionally exchanged $500.0 million at an interest rate of 5.375% for €420 million at a weighted average interest rate of 3.45% for approximately five years.

Effective September 1, 2017, the Company designated the full notional amount of the CCS (€420 million) as a hedge of the Issuers’ net investment in certain European subsidiaries. As the CCS were deemed to be highly effective hedges, changes in the fair value of the CCS were recorded as cumulative foreign currency translation loss of $38.0 million within AOCI as of March 31, 2018.

Summary of Derivative Instruments

Information regarding changes in the fair value of the Company’s derivative instruments, net of tax, including those not designated for hedge accounting treatment, is as follows:


	Gain (Loss) Recognized in				Gain (Loss) Recognized in
	AOCI on Balance Sheet				Statement of Operations
	Three Months Ended March 31,								Statement of Operations
	2018		2017		2018		2017		Classification
Designated as Cash Flow Hedges
Foreign exchange cash flow hedges	$	(0.5)	$	(4.8)	$	(3.7)	$	2.5	Cost of sales
Interest rate swaps		3.3		—		(0.1)		—	Interest expense, net
Total	$	2.8	$	(4.8)	$	(3.8)	$	2.5
Net Investment Hedges
Euro Notes	$	—	$	(5.0)	$	—	$	—
Cross-currency swaps (CCS)		(20.4)		—		—		—
Total	$	(20.4)	$	(5.0)	$	—	$	—
Not Designated as Cash Flow Hedges
Foreign exchange forward contracts	$	—	$	—	$	(5.3)	$	(1.7)	Other income, net
Total	$	—	$	—	$	(5.3)	$	(1.7)

The Company recorded losses of $5.3 million and $1.7 million during the three months ended March 31, 2018 and 2017, respectively, from settlements and changes in the fair value of outstanding forward contracts (not designated as hedges). The losses from these forward contracts offset net foreign exchange transaction gains of $10.4 million and $0.6 million during the three months ended March 31, 2018 and 2017, respectively, which resulted from the remeasurement of the Company’s foreign currency denominated assets and liabilities. The cash settlements of these foreign exchange forward contracts are included within operating activities in the condensed consolidated statement of cash flows.

As of March 31, 2018, the Company had no ineffectiveness related to its derivatives designated as hedging instruments. Further, the Company expects to reclassify in the next twelve months an approximate $11.5 million net loss from AOCI into earnings related to the Company’s outstanding foreign exchange cash flow hedges and interest rate swaps as of March 31, 2018 based on current foreign exchange rates.

The following table summarizes the net unrealized gains and losses and balance sheet classification of outstanding derivatives recorded in the condensed consolidated balance sheets:


	March 31, 2018										December 31, 2017
	Foreign		Foreign								Foreign		Foreign
	Exchange		Exchange		Interest		Cross-				Exchange		Exchange		Interest		Cross-
Balance Sheet	Forward		Cash Flow		Rate		Currency				Forward		Cash Flow		Rate		Currency
Classification	Contracts		Hedges		Swaps		Swaps		Total		Contracts		Hedges		Swaps		Swaps		Total
Asset Derivatives:
Accounts receivable, net of allowance	$	0.3	$	—	$	0.6	$	10.4	$	11.3	$	0.1	$	—	$	—	$	10.8	$	10.9
Deferred charges and other assets		—		—		5.6		—		5.6		—		—		3.0		—		3.0
Total asset derivatives	$	0.3	$	—	$	6.2	$	10.4	$	16.9	$	0.1	$	—	$	3.0	$	10.8	$	13.9
Liability Derivatives:
Accounts payable	$	2.8	$	12.1	$	—	$	—	$	14.9	$	2.5	$	11.1	$	0.1	$	—	$	13.7
Other noncurrent obligations		—		—		—		48.3		48.3		—		—		—		28.3		28.3
Total liability derivatives	$	2.8	$	12.1	$	—	$	48.3	$	63.2	$	2.5	$	11.1	$	0.1	$	28.3	$	42.0

Forward contracts, interest rate swaps, 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. Information regarding the gross amounts of the Company’s derivative instruments and the amounts offset in the condensed consolidated balance sheets is as follows:


	Gross Amounts		Gross Amounts		Net Amounts
	Recognized in the		Offset in the		Presented in the
	Balance Sheet		Balance Sheet		Balance Sheet
Balance at March 31, 2018
Derivative assets - Current	$	11.4	$	(0.1)	$	11.3
Derivative assets - Non-Current		5.6		—		5.6
Derivative liabilities - Current		15.0		(0.1)		14.9
Derivative liabilities - Non-Current		48.3		—		48.3

Balance at December 31, 2017
Derivative assets - Current	$	11.5	$	(0.6)	$	10.9
Derivative assets - Non-Current		3.0		—		3.0
Derivative liabilities - Current		14.3		(0.6)		13.7
Derivative liabilities - Non-Current		28.3		—		28.3

Refer to Notes 9 and 17 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

3 Months Ended

Mar. 31, 2018

Fair Value Measurements

Fair Value Measurements

NOTE 9—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, 2018 and December 31, 2017:


	March 31, 2018
	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	$	—	$	0.3	$	—	$	0.3
Foreign exchange forward contracts—(Liabilities)		—		(2.8)		—		(2.8)
Foreign exchange cash flow hedges—(Liabilities)		—		(12.1)		—		(12.1)
Interest rate swaps—Assets		—		6.2		—		6.2
Cross-currency swaps—Assets		—		10.4		—		10.4
Cross-currency swaps—(Liabilities)		—		(48.3)		—		(48.3)
Total fair value	$	—	$	(46.3)	$	—	$	(46.3)


	December 31, 2017
	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)		—		(2.5)		—		(2.5)
Foreign exchange cash flow hedges—(Liabilities)		—		(11.1)		—		(11.1)
Interest rate swaps—Assets		—		3.0		—		3.0
Interest rate swaps—(Liabilities)		—		(0.1)		—		(0.1)
Cross-currency swaps—Assets		—		10.8		—		10.8
Cross-currency swaps—(Liabilities)		—		(28.3)		—		(28.3)
Total fair value	$	—	$	(28.1)	$	—	$	(28.1)

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.

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, 2018 and December 31, 2017, respectively:


	As of		As of
	March 31, 2018		December 31, 2017
2025 Senior Notes	$	495.2	$	518.8
2024 Term Loan B		701.7		705.7
Total fair value	$	1,196.9	$	1,224.5

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.

There were no other significant financial instruments outstanding as of March 31, 2018 and December 31, 2017.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Provision for Income Taxes

3 Months Ended

Mar. 31, 2018

Provision for Income Taxes

Income Taxes

NOTE 10—PROVISION FOR INCOME TAXES


	Three Months Ended
	March 31,
	2018			2017
Effective income tax rate		17.1	%		20.0	%

Provision for income taxes for the three months ended March 31, 2018 totaled $24.9 million, resulting in an effective tax rate of 17.1%. Provision for income taxes for the three months ended March 31, 2017 totaled $29.3 million, resulting in an effective tax rate of 20.0%.

The decrease in the effective tax rate for the three months ended March 31, 2018 as compared to the same period in 2017 was primarily driven by the reduction in the U.S. federal corporate tax rate from 35% to 21%, effective January 1, 2018, in accordance with the enactment of the Tax Cuts and Jobs Act signed into law on December 22, 2017. The decrease related to the reduction in the U.S. federal corporate tax rate effective in 2018 was partially offset by the $9.3 million gain on sale of the Company’s 50% share in Sumika Styron Polycarbonate during the three months ended March 31, 2017, which was exempt from tax (refer to Note 4 for further information).

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2018
Commitments and Contingencies Disclosure
Commitments and Contingencies	NOTE 11—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 conditions were retained by Dow and Dow has agreed to indemnify the Company from and against all environmental liabilities incurred or relating to the predecessor periods. No environmental claims have been asserted or threatened against the Company, and the Company is not a potentially responsible party at any Superfund Sites. As of March 31, 2018 and December 31, 2017, the Company had no accrued obligations for environmental remediation and restoration costs. 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. 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 1 to 4 years. In certain raw material purchase contracts, the Company has the right to purchase less than the required minimums and pay a liquidated damages fee, or, in case of a permanent plant shutdown, to terminate the contracts. In such cases, these obligations would be less than the annual commitment as disclosed in the Notes to Consolidated Financial Statements included in the Annual Report. 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 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.

Pension Plans and Other Postretirement Benefits

3 Months Ended

Mar. 31, 2018

Pension Plans and Other Postretirement Benefits

Pension Plans and Other Postretirement Benefits

NOTE 12—PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS

The components of net periodic benefit costs for all significant plans were as follows:


	Three Months Ended
	March 31,
	2018		2017
Defined Benefit Pension Plans
Service cost	$	3.1	$	4.6
Interest cost		1.3		1.1
Expected return on plan assets		(0.6)		(0.4)
Amortization of prior service credit		(0.3)		(0.5)
Amortization of net loss		1.0		1.4
Net settlement and curtailment loss(1)		—		0.1
Net periodic benefit cost	$	4.5	$	6.3

(1)

Represents a settlement loss of approximately $0.5 million triggered by benefit payments exceeding the sum of service and interest cost for one of the Company’s pension plans in Switzerland, partially offset by a curtailment gain of approximately $0.4 million related to a reduction in the number of participants in the Company’s pension plan in Japan.


	Three Months Ended
	March 31,
	2018		2017
Other Postretirement Plans
Service cost	$	—	$	0.1
Interest cost		0.1		0.1
Amortization of prior service cost		—		—
Amortization of net gain		—		—
Net periodic benefit cost	$	0.1	$	0.2

In accordance with recently issued accounting standards, 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 income, net” in the condensed consolidated statements of operations. Refer to Note 2 for further information.

As of March 31, 2018 and December 31, 2017, the Company’s benefit obligations included primarily in “Other noncurrent obligations” in the condensed consolidated balance sheets were $195.2 million and $188.7 million, respectively.

The Company made cash contributions and benefit payments to unfunded plans of approximately $2.0 million during the three months ended March 31, 2018. The Company expects to make additional cash contributions, including benefit payments to unfunded plans, of approximately $4.5 million to its defined benefit plans for the remainder of 2018.

Stock-Based Compensation

3 Months Ended

Mar. 31, 2018

Stock-Based Compensation

Stock-Based Compensation

NOTE 13—STOCK-BASED COMPENSATION

Refer to the Annual Report for definitions of capitalized terms not included herein and further background on the Company’s stock-based compensation programs included in the tables below.

The following table summarizes the Company’s stock-based compensation expense for the three months ended March 31, 2018 and 2017, as well as unrecognized compensation cost as of March 31, 2018:


					As of
	Three Months Ended				March 31, 2018
	March 31,				Unrecognized		Weighted
	2018		2017		Compensation Cost		Average Years
RSUs	$	2.2	$	1.9	$	14.9	2.2
Options		2.8		2.6		2.9	1.6
PSUs		0.5		0.2		6.7	2.5
Total stock-based compensation expense	$	5.5	$	4.7

The following table summarizes awards granted and the respective weighted average grant date fair value for the three months ended March 31, 2018:


	Three Months Ended
	March 31, 2018
	Awards Granted		Weighted Average Grant Date Fair Value per Award
RSUs		97,676	$	81.20
Options		202,963		22.29
PSUs		50,289		88.51

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, 2018:


	Three Months Ended
	March 31,
	2018
Expected term (in years)	5.50
Expected volatility	32.00	%
Risk-free interest rate	2.71	%
Dividend yield	2.00	%

Since the Company’s equity interests were privately held prior to its initial public offering (“IPO”) in June 2014, there is limited publicly traded history of the Company’s ordinary shares. Until such time that the Company can determine expected volatility based solely on the publicly traded history of its ordinary shares, expected volatility used in the Black-Scholes model for option awards granted is based on a combination of the Company’s historical volatility and similar companies’ stock that are publicly traded. 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, 2018, 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, 2018:


		Three Months Ended
		March 31,
		2018
Expected term (in years)		3.00
Expected volatility		36.00	%
Risk-free interest rate		2.42	%
Stock price	$	81.20

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 stock 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 stock price is the closing price of the Company’s ordinary shares on the grant date.

Acquisitions and Divestitures	3 Months Ended
Acquisitions and Divestitures	Mar. 31, 2018
Acquisitions and Divestitures
Acquisitions and Divestitures	NOTE 14—ACQUISITIONS AND DIVESTITURES Acquisition of API Plastics On July 10, 2017, the Company acquired 100% of the equity interests of API Applicazioni Plastiche Industriali S.p.A, or API Plastics, a privately held company. The gross purchase price for the acquisition was $90.6 million, inclusive of $8.4 million of cash acquired, yielding a net purchase price of $82.3 million, all of which was paid for during the year ended December 31, 2017 (noting no cash flows during the three months ended March 31, 2017). API Plastics, based in Mussolente, Italy, is a manufacturer of soft-touch polymers and bioplastics, such as thermoplastic elastomers (“TPEs”), whose results are included within our Performance Plastics 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. During the first quarter of 2018, there were no changes to the purchase price allocation for the acquisition of API Plastics. However, further adjustments may be necessary as a result of the Company’s on-going assessment of additional information related to the fair value of assets acquired and liabilities assumed, including goodwill, during the measurement period. During the three months ended March 31, 2018, transaction and integration costs related to advisory and professional fees incurred in conjunction with the API Plastics acquisition were $0.3 million, and were included within “Selling, general and administrative expenses” in the condensed consolidated statement of operations. Refer to the Annual Report for further information.

Segments

3 Months Ended

Mar. 31, 2018

Segments

Segments

NOTE 15—SEGMENTS

Through December 31, 2017, the Company operated under two divisions: Performance Materials and Basic Plastics & Feedstocks. The Performance Materials division included the following reporting segments: Latex Binders, Synthetic Rubber, and Performance Plastics. The Basic Plastics & Feedstocks division included the following reporting segments: Basic Plastics, Feedstocks, and Americas Styrenics.

Effective January 1, 2018, the Company realigned its reporting segments to reflect the new model under which the business will be managed and results will be reviewed by the chief executive officer, who is the Company’s chief operating decision maker. Under this new segmentation, the Company will no longer have divisions, but will continue to report operating results for six segments, four of which remain unchanged from the Company’s prior segmentation: Latex Binders, Synthetic Rubber, Feedstocks, and Americas Styrenics. The results of our Polystyrene business, which was previously included within the results of the Basic Plastics segment, are now reported as a stand-alone segment. Performance Plastics, which previously consisted of compounds, blends, and ABS products sold to the automotive market, now includes the remaining portion of the Company’s ABS business, as well as the results of the Company’s SAN and PC businesses. This segmentation change will provide enhanced clarity to investors by concentrating the Company’s more specialized plastics into a single reporting segment, while also reducing complexity as PC and ABS are the primary inputs into the downstream production of the Company’s compounds and blends. The information in the tables below has been retroactively adjusted to reflect the changes in reporting segments.

The Latex Binders segment produces styrene-butadiene latex, or 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 Synthetic Rubber segment produces synthetic rubber products used predominantly in high-performance tires, impact modifiers and technical rubber products, such as conveyer belts, hoses, seals and gaskets. The Performance Plastics segment produces highly engineered compounds and blends, and also includes our ABS, SAN, and PC businesses. The Performance Plastics segment, as recast, also included the results of our previously 50%-owned joint venture, Sumika Styron Polycarbonate, until the Company sold its share in the entity in January 2017 (refer to Note 4 for further information). Polystyrene is a stand-alone reporting segment, and includes a variety of general purpose polystyrenes, or GPPS, as well as HIPS, which is polystyrene that has been modified with polybutadiene rubber to increase its impact resistant properties. 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, ABS resins, solution styrene-butadiene rubber, or SSBR, etc. Lastly, the Americas Styrenics segment consists solely of the operations of our 50%-owned joint venture, Americas Styrenics, a producer of both styrene monomer and polystyrene in North America.

Asset, capital expenditure, 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.


	Latex		Synthetic		Performance						Americas		Corporate
Three Months Ended	Binders		Rubber		Plastics		Polystyrene		Feedstocks		Styrenics		Unallocated		Total
March 31, 2018
Sales to external customers	$	255.3	$	149.2	$	402.9	$	239.6	$	74.6	$	—	$	—	$	1,121.6
Equity in earnings (losses) of unconsolidated affiliates		—		—		—		—		—		45.5		—		45.5
Adjusted EBITDA(1)		27.5		25.5		65.5		9.6		41.5		45.5
Investment in unconsolidated affiliates		—		—		—		—		—		168.1		—		168.1
Depreciation and amortization		6.1		11.2		6.4		2.9		3.0		—		2.3		31.9
March 31, 2017
Sales to external customers	$	288.9	$	163.4	$	336.9	$	228.4	$	86.9	$	—	$	—	$	1,104.5
Equity in earnings (losses) of unconsolidated affiliates		—		—		0.8		—		—		18.5		—		19.3
Adjusted EBITDA(1)		36.8		46.3		52.2		13.6		41.9		18.5
Investment in unconsolidated affiliates		—		—		—		—		—		160.6		—		160.6
Depreciation and amortization		5.7		8.4		4.0		2.0		2.5		—		2.1		24.7

(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 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 before income taxes to Segment Adjusted EBITDA is as follows:


	Three Months Ended
	March 31,
	2018		2017
Income before income taxes	$	145.2	$	146.6
Interest expense, net		14.9		18.2
Depreciation and amortization		31.9		24.7
Corporate Unallocated(2)		20.1		27.6
Adjusted EBITDA Addbacks(3)		3.0		(7.8)
Segment Adjusted EBITDA	$	215.1	$	209.3

(2)Corporate unallocated includes corporate overhead costs and certain other income and expenses.

(3)Adjusted EBITDA addbacks for the three months ended March 31, 2018 and 2017 are as follows:


	Three Months Ended
	March 31,
	2018		2017
Net gain on disposition of businesses and assets (Note 4)	$	(0.5)	$	(9.9)
Restructuring and other charges (Note 16)		0.5		2.1
Acquisition transaction and integration costs (Note 14)		0.3		—
Other items(a)		2.7		—
Total Adjusted EBITDA Addbacks	$	3.0	$	(7.8)

(a)

Other items for the three months ended March 31, 2018 relate to advisory and professional fees incurred in conjunction with the Company’s initiative to transition business services from Dow, including certain administrative services such as accounts payable, logistics, and IT services.

.

Restructuring

3 Months Ended

Mar. 31, 2018

Restructuring

Restructuring

NOTE 16—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, 2018 and 2017:


	Three Months Ended				Cumulative
	March 31,				Life-to-date
	2018		2017		Charges		Segment
Terneuzen Compounding Restructuring(1)
Asset impairment/accelerated depreciation	$	0.3	$	0.6	$	2.3
Employee termination benefits		0.1		—		0.7
Contract terminations		—		0.6		0.6
Decommissioning and other		—		—		0.8
Terneuzen Subtotal	$	0.4	$	1.2	$	4.4	Performance Plastics
Livorno Plant Restructuring(2)
Asset impairment/accelerated depreciation	$	—	$	—	$	14.3
Employee termination benefits		—		0.2		5.4
Contract terminations		—		—		0.3
Decommissioning and other		0.3		0.6		3.3
Livorno Subtotal	$	0.3	$	0.8	$	23.3	Latex Binders
Other Restructurings		0.1		0.7			Various
Total Restructuring Charges	$	0.8	$	2.7

(1)

In March 2017, the Company announced plans to upgrade its production capability for compounded resins with the construction of a new state-of-the art compounding facility to replace its existing compounding facility in Terneuzen, The Netherlands. The new facility is expected to be operational by the end of 2018, with substantive production at the existing facility expected to cease by December 2018, followed by decommissioning activities in 2019. The Company expects to incur incremental accelerated depreciation charges of approximately $0.9 million through the end of 2018, as well as estimated employee termination benefit charges and decommissioning and other charges of approximately $0.9 million throughout 2019, the majority of which are expected to be paid throughout 2019.

(2)

In August 2016, the Company announced its plan to cease manufacturing activities at its latex binders manufacturing facility in Livorno, Italy. Production at the facility ceased in October 2016, followed by decommissioning activities which began in the fourth quarter of 2016. The Company does not expect to incur additional employee termination benefit charges related to this restructuring. The Company expects to incur additional decommissioning costs associated with this plant shutdown in 2018, the cost of which will be expensed as incurred.

The following table provides a rollforward of the liability balances associated with the Company’s restructuring activities as of March 31, 2018. Employee termination benefit and contract termination charges are recorded within “Accrued expenses and other current liabilities” in the condensed consolidated balance sheet.


	Balance at						Balance at
	December 31, 2017		Expenses		Deductions(1)		March 31, 2018
Employee termination benefits	$	1.4	$	0.1	$	(0.6)	$	0.9
Contract terminations		0.6		—		—		0.6
Decommissioning and other		—		0.4		(0.4)		—
Total	$	2.0	$	0.5	$	(1.0)	$	1.5

(1)

Includes primarily payments made against the existing accrual, as well as immaterial impacts of foreign currency remeasurement.

.

Accumulated Other Comprehensive Income (Loss)

3 Months Ended

Mar. 31, 2018

Shareholders' Equity.

Accumulated Other Comprehensive Income (Loss)

NOTE 17—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, 2018 and 2017	Adjustments		Plans, Net		Hedges, Net		Total
Balance at December 31, 2017	$	(94.5)	$	(45.0)	$	(6.1)	$	(145.6)
Other comprehensive income (loss)		(2.1)		—		(1.0)		(3.1)
Amounts reclassified from AOCI to net income (1)		—		0.6		3.8		4.4
Balance at March 31, 2018	$	(96.6)	$	(44.4)	$	(3.3)	$	(144.3)

Balance as of December 31, 2016	$	(119.0)	$	(63.5)	$	12.3	$	(170.2)
Other comprehensive income (loss)		4.2		—		(2.3)		1.9
Amounts reclassified from AOCI to net income (1)		—		1.4		(2.5)		(1.1)
Balance as of March 31, 2017	$	(114.8)	$	(62.1)	$	7.5	$	(169.4)

(1)

The following is a summary of amounts reclassified from AOCI to net income for the three months ended March 31, 2018 and 2017, respectively:


	Amount Reclassified from AOCI
AOCI Components	Three Months Ended March 31,				Statement of Operations
	2018		2017		Classification
Cash flow hedging items
Foreign exchange cash flow hedges	$	3.7	$	(2.5)	Cost of sales
Interest rate swaps		0.1		—	Interest expense, net
Total before tax		3.8		(2.5)
Tax effect		—		—	Provision for income taxes
Total, net of tax	$	3.8	$	(2.5)

Amortization of pension and other postretirement benefit plan items
Prior service credit	$	(0.2)	$	(0.4)	(a)
Net actuarial loss		1.1		1.6	(a)
Net settlement and curtailment loss		—		0.6	(a)
Total before tax		0.9		1.8
Tax effect		(0.3)		(0.4)	Provision for income taxes
Total, net of tax	$	0.6	$	1.4

(a)

These AOCI components are included in the computation of net periodic benefit costs (see Note 12).

.

Earnings Per Share

3 Months Ended

Mar. 31, 2018

Earnings Per Share

Earnings Per Share

NOTE 18—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 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, 2018 and 2017, respectively:


	Three Months Ended
	March 31,
(in millions, except per share data)	2018		2017
Earnings:
Net income	$	120.3	$	117.3
Shares:
Weighted average ordinary shares outstanding		43.4		44.1
Dilutive effect of RSUs, option awards, and PSUs*		1.0		1.2
Diluted weighted average ordinary shares outstanding		44.4		45.3
Income per share:
Income per share—basic	$	2.77	$	2.66
Income per share—diluted	$	2.71	$	2.59

* Refer to Note 13 for discussion of RSUs, option awards, and PSUs granted to certain Company directors and employees. The number of anti-dilutive shares that have been excluded in the computation of diluted earnings per share for the three months ended March 31, 2018 and 2017 were 0.2 million and 0.2 million, respectively.

Basis of Presentation (Policies)	3 Months Ended
Basis of Presentation (Policies)	Mar. 31, 2018
Basis of Presentation.
Basis of Presentation	The unaudited interim condensed consolidated financial statements of Trinseo S.A. and its subsidiaries (the “Company”) as of and for the periods ended March 31, 2018 and 2017 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 2017 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 March 1, 2018. The December 31, 2017 condensed consolidated balance sheet data presented herein was derived from the Company’s December 31, 2017 audited consolidated financial statements, but does not include all disclosures required by GAAP for annual periods. Certain prior year amounts have been reclassified to conform to the current period presentation. These reclassifications did not have a material impact on the Company’s financial position or results. Refer to Notes 2, 7, and 15 for further information.

Net Sales (Tables)

3 Months Ended

Mar. 31, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]


	Three Months Ended
	March 31, 2018
	Latex		Synthetic		Performance
	Binders		Rubber		Plastics		Polystyrene		Feedstocks		Total
United States	$	64.3	$	—	$	84.1	$	0.2	$	3.7	$	152.3
Europe		113.3		149.2		249.2		148.2		57.9		717.8
Asia-Pacific		74.3		—		47.3		91.2		13.0		225.8
Rest of World		3.4		—		22.3		—		—		25.7
Total	$	255.3	$	149.2	$	402.9	$	239.6	$	74.6	$	1,121.6


	Three Months Ended
	March 31, 2017(1)
	Latex		Synthetic		Performance
	Binders		Rubber		Plastics		Polystyrene		Feedstocks		Total
United States	$	76.0	$	—	$	82.8	$	0.2	$	3.8	$	162.8
Europe		119.5		163.4		199.4		140.1		34.7		657.1
Asia-Pacific		89.0		—		32.7		88.1		48.4		258.2
Rest of World		4.4		—		22.0		—		—		26.4
Total	$	288.9	$	163.4	$	336.9	$	228.4	$	86.9	$	1,104.5

(1)

As the Company has adopted Topic 606 utilizing the modified retrospective approach, amounts for the three months ended March 31, 2017 above are disclosed as recognized under Topic 605.

Investments in Unconsolidated Affiliates (Tables)

3 Months Ended

Mar. 31, 2018

Investments in Unconsolidated Affiliates

Summarized Financial Information of Unconsolidated Affiliates


	Three Months Ended
	March 31,
	2018		2017
Sales	$	486.6	$	433.9
Gross profit	$	95.2	$	20.6
Net income	$	85.7	$	6.3

Inventories (Tables)

3 Months Ended

Mar. 31, 2018

Inventories

Schedule of Inventories


	March 31,		December 31,
	2018		2017
Finished goods	$	285.6	$	250.9
Raw materials and semi-finished goods		265.1		226.7
Supplies		37.6		32.8
Total	$	588.3	$	510.4

Debt (Tables)

3 Months Ended

Mar. 31, 2018

Debt

Schedule of Debt [Table Text Block]

			March 31, 2018						December 31, 2017
	Interest Rate as of March 31, 2018	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
2022 Revolving Facility(2)	Various	September 2022	$	—	$	—	$	—	$	—	$	—	$	—
2024 Term Loan B(3)	4.377%	September 2024		696.5		(17.8)		678.7		698.3		(18.3)		680.0
2025 Senior Notes	5.375%	September 2025		500.0		(9.1)		490.9		500.0		(9.4)		490.6
Accounts Receivable Securitization Facility(4)	Various	May 2019		—		—		—		—		—		—
Other indebtedness	Various	Various		1.4		—		1.4		1.4		—		1.4
Total debt			$	1,197.9	$	(26.9)	$	1,171.0	$	1,199.7	$	(27.7)	$	1,172.0
Less: current portion								(7.0)						(7.0)
Total long-term debt, net of unamortized deferred financing fees							$	1,164.0					$	1,165.0

(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)

Under the 2022 Revolving Facility, the Company had a capacity of $375.0 million and funds available for borrowing of $359.9 million (net of $15.1 million outstanding letters of credit) as of March 31, 2018. 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)

The 2024 Term Loan B bears an interest rate of LIBOR plus 2.50%, subject to a 0.00% LIBOR floor. As of March 31, 2018, $7.0 million of the scheduled future payments related to this facility were classified as current debt on the Company’s condensed consolidated balance sheet.

(4)

This facility had a borrowing capacity of $150.0 million as of March 31, 2018. Additionally, as of March 31, 2018, the Company had accounts receivable available to support this facility in excess of its borrowing capacity, based on the pool of eligible accounts receivable. In regard to outstanding borrowings, fixed interest charges are 1.95% plus variable commercial paper rates, while for available, but undrawn commitments, fixed interest charges are 1.0%.

Goodwill and Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets.

Changes in Carrying Amount of Goodwill, by Segment


	Latex		Synthetic		Performance						Americas
	Binders		Rubber		Plastics		Polystyrene		Feedstocks		Styrenics		Total
Balance at December 31, 2017	$	16.5	$	11.7	$	39.6	$	4.7	$	—	$	—	$	72.5
Foreign currency impact		0.4		0.3		0.9		0.1		—		—		1.7
Balance at March 31, 2018	$	16.9	$	12.0	$	40.5	$	4.8	$	—	$	—	$	74.2

Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Derivative Instruments [Abstract]

Notional Amounts of Most Significant Net Foreign Exchange Hedge Positions Outstanding


	March 31,
Buy / (Sell)	2018
Euro	$	(129.4)
Chinese Yuan	$	(78.2)
Swiss Franc	$	54.6
Taiwan Dollar	$	14.4
Indonesian Rupiah	$	(14.0)

Schedule of Changes in Fair Value of Company's Derivatives Instruments


	Gain (Loss) Recognized in				Gain (Loss) Recognized in
	AOCI on Balance Sheet				Statement of Operations
	Three Months Ended March 31,								Statement of Operations
	2018		2017		2018		2017		Classification
Designated as Cash Flow Hedges
Foreign exchange cash flow hedges	$	(0.5)	$	(4.8)	$	(3.7)	$	2.5	Cost of sales
Interest rate swaps		3.3		—		(0.1)		—	Interest expense, net
Total	$	2.8	$	(4.8)	$	(3.8)	$	2.5
Net Investment Hedges
Euro Notes	$	—	$	(5.0)	$	—	$	—
Cross-currency swaps (CCS)		(20.4)		—		—		—
Total	$	(20.4)	$	(5.0)	$	—	$	—
Not Designated as Cash Flow Hedges
Foreign exchange forward contracts	$	—	$	—	$	(5.3)	$	(1.7)	Other income, net
Total	$	—	$	—	$	(5.3)	$	(1.7)

Net Unrealized Gains and Losses Recorded in Consolidated Balance Sheets


	March 31, 2018										December 31, 2017
	Foreign		Foreign								Foreign		Foreign
	Exchange		Exchange		Interest		Cross-				Exchange		Exchange		Interest		Cross-
Balance Sheet	Forward		Cash Flow		Rate		Currency				Forward		Cash Flow		Rate		Currency
Classification	Contracts		Hedges		Swaps		Swaps		Total		Contracts		Hedges		Swaps		Swaps		Total
Asset Derivatives:
Accounts receivable, net of allowance	$	0.3	$	—	$	0.6	$	10.4	$	11.3	$	0.1	$	—	$	—	$	10.8	$	10.9
Deferred charges and other assets		—		—		5.6		—		5.6		—		—		3.0		—		3.0
Total asset derivatives	$	0.3	$	—	$	6.2	$	10.4	$	16.9	$	0.1	$	—	$	3.0	$	10.8	$	13.9
Liability Derivatives:
Accounts payable	$	2.8	$	12.1	$	—	$	—	$	14.9	$	2.5	$	11.1	$	0.1	$	—	$	13.7
Other noncurrent obligations		—		—		—		48.3		48.3		—		—		—		28.3		28.3
Total liability derivatives	$	2.8	$	12.1	$	—	$	48.3	$	63.2	$	2.5	$	11.1	$	0.1	$	28.3	$	42.0

Gross Amounts of Derivative Instruments and Amounts Offset


	Gross Amounts		Gross Amounts		Net Amounts
	Recognized in the		Offset in the		Presented in the
	Balance Sheet		Balance Sheet		Balance Sheet
Balance at March 31, 2018
Derivative assets - Current	$	11.4	$	(0.1)	$	11.3
Derivative assets - Non-Current		5.6		—		5.6
Derivative liabilities - Current		15.0		(0.1)		14.9
Derivative liabilities - Non-Current		48.3		—		48.3

Balance at December 31, 2017
Derivative assets - Current	$	11.5	$	(0.6)	$	10.9
Derivative assets - Non-Current		3.0		—		3.0
Derivative liabilities - Current		14.3		(0.6)		13.7
Derivative liabilities - Non-Current		28.3		—		28.3

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Measurements

Schedule of Assets and Liabilities at Fair Value on Recurring Basis


	March 31, 2018
	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	$	—	$	0.3	$	—	$	0.3
Foreign exchange forward contracts—(Liabilities)		—		(2.8)		—		(2.8)
Foreign exchange cash flow hedges—(Liabilities)		—		(12.1)		—		(12.1)
Interest rate swaps—Assets		—		6.2		—		6.2
Cross-currency swaps—Assets		—		10.4		—		10.4
Cross-currency swaps—(Liabilities)		—		(48.3)		—		(48.3)
Total fair value	$	—	$	(46.3)	$	—	$	(46.3)


	December 31, 2017
	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)		—		(2.5)		—		(2.5)
Foreign exchange cash flow hedges—(Liabilities)		—		(11.1)		—		(11.1)
Interest rate swaps—Assets		—		3.0		—		3.0
Interest rate swaps—(Liabilities)		—		(0.1)		—		(0.1)
Cross-currency swaps—Assets		—		10.8		—		10.8
Cross-currency swaps—(Liabilities)		—		(28.3)		—		(28.3)
Total fair value	$	—	$	(28.1)	$	—	$	(28.1)

Estimated Fair Value of Outstanding Debt Not Carried at Fair Value


	As of		As of
	March 31, 2018		December 31, 2017
2025 Senior Notes	$	495.2	$	518.8
2024 Term Loan B		701.7		705.7
Total fair value	$	1,196.9	$	1,224.5

Income Taxes (Tables)

3 Months Ended

Mar. 31, 2018

Provision for Income Taxes

Schedule of Effective Tax Rate


	Three Months Ended
	March 31,
	2018			2017
Effective income tax rate		17.1	%		20.0	%

Pension Plans and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2018

Defined Benefit Pension Plans

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Net Periodic Benefit Costs


	Three Months Ended
	March 31,
	2018		2017
Defined Benefit Pension Plans
Service cost	$	3.1	$	4.6
Interest cost		1.3		1.1
Expected return on plan assets		(0.6)		(0.4)
Amortization of prior service credit		(0.3)		(0.5)
Amortization of net loss		1.0		1.4
Net settlement and curtailment loss(1)		—		0.1
Net periodic benefit cost	$	4.5	$	6.3

(1)

Represents a settlement loss of approximately $0.5 million triggered by benefit payments exceeding the sum of service and interest cost for one of the Company’s pension plans in Switzerland, partially offset by a curtailment gain of approximately $0.4 million related to a reduction in the number of participants in the Company’s pension plan in Japan.

Other Postretirement Plans

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Net Periodic Benefit Costs


	Three Months Ended
	March 31,
	2018		2017
Other Postretirement Plans
Service cost	$	—	$	0.1
Interest cost		0.1		0.1
Amortization of prior service cost		—		—
Amortization of net gain		—		—
Net periodic benefit cost	$	0.1	$	0.2

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Stock-Based Compensation Expense and Unrecognized Compensation Cost


					As of
	Three Months Ended				March 31, 2018
	March 31,				Unrecognized		Weighted
	2018		2017		Compensation Cost		Average Years
RSUs	$	2.2	$	1.9	$	14.9	2.2
Options		2.8		2.6		2.9	1.6
PSUs		0.5		0.2		6.7	2.5
Total stock-based compensation expense	$	5.5	$	4.7

Summary of Awards Granted and Weighted Average Grant-Date Fair Value


	Three Months Ended
	March 31, 2018
	Awards Granted		Weighted Average Grant Date Fair Value per Award
RSUs		97,676	$	81.20
Options		202,963		22.29
PSUs		50,289		88.51

Option Awards

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Weighted-average Assumptions


	Three Months Ended
	March 31,
	2018
Expected term (in years)	5.50
Expected volatility	32.00	%
Risk-free interest rate	2.71	%
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,
		2018
Expected term (in years)		3.00
Expected volatility		36.00	%
Risk-free interest rate		2.42	%
Stock price	$	81.20

Segments (Tables)

3 Months Ended

Mar. 31, 2018

Segments

Schedule of Segment Reporting Information, by Segment [Table Text Block]


	Latex		Synthetic		Performance						Americas		Corporate
Three Months Ended	Binders		Rubber		Plastics		Polystyrene		Feedstocks		Styrenics		Unallocated		Total
March 31, 2018
Sales to external customers	$	255.3	$	149.2	$	402.9	$	239.6	$	74.6	$	—	$	—	$	1,121.6
Equity in earnings (losses) of unconsolidated affiliates		—		—		—		—		—		45.5		—		45.5
Adjusted EBITDA(1)		27.5		25.5		65.5		9.6		41.5		45.5
Investment in unconsolidated affiliates		—		—		—		—		—		168.1		—		168.1
Depreciation and amortization		6.1		11.2		6.4		2.9		3.0		—		2.3		31.9
March 31, 2017
Sales to external customers	$	288.9	$	163.4	$	336.9	$	228.4	$	86.9	$	—	$	—	$	1,104.5
Equity in earnings (losses) of unconsolidated affiliates		—		—		0.8		—		—		18.5		—		19.3
Adjusted EBITDA(1)		36.8		46.3		52.2		13.6		41.9		18.5
Investment in unconsolidated affiliates		—		—		—		—		—		160.6		—		160.6
Depreciation and amortization		5.7		8.4		4.0		2.0		2.5		—		2.1		24.7

(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 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,
	2018		2017
Income before income taxes	$	145.2	$	146.6
Interest expense, net		14.9		18.2
Depreciation and amortization		31.9		24.7
Corporate Unallocated(2)		20.1		27.6
Adjusted EBITDA Addbacks(3)		3.0		(7.8)
Segment Adjusted EBITDA	$	215.1	$	209.3

(2)Corporate unallocated includes corporate overhead costs and certain other income and expenses.

(3)Adjusted EBITDA addbacks for the three months ended March 31, 2018 and 2017 are as follows:


	Three Months Ended
	March 31,
	2018		2017
Net gain on disposition of businesses and assets (Note 4)	$	(0.5)	$	(9.9)
Restructuring and other charges (Note 16)		0.5		2.1
Acquisition transaction and integration costs (Note 14)		0.3		—
Other items(a)		2.7		—
Total Adjusted EBITDA Addbacks	$	3.0	$	(7.8)

(a)

Other items for the three months ended March 31, 2018 relate to advisory and professional fees incurred in conjunction with the Company’s initiative to transition business services from Dow, including certain administrative services such as accounts payable, logistics, and IT services.

Restructuring (Tables)

3 Months Ended

Mar. 31, 2018

Restructuring

Detail of Restructuring Charges

	Three Months Ended				Cumulative
	March 31,				Life-to-date
	2018		2017		Charges		Segment
Terneuzen Compounding Restructuring(1)
Asset impairment/accelerated depreciation	$	0.3	$	0.6	$	2.3
Employee termination benefits		0.1		—		0.7
Contract terminations		—		0.6		0.6
Decommissioning and other		—		—		0.8
Terneuzen Subtotal	$	0.4	$	1.2	$	4.4	Performance Plastics
Livorno Plant Restructuring(2)
Asset impairment/accelerated depreciation	$	—	$	—	$	14.3
Employee termination benefits		—		0.2		5.4
Contract terminations		—		—		0.3
Decommissioning and other		0.3		0.6		3.3
Livorno Subtotal	$	0.3	$	0.8	$	23.3	Latex Binders
Other Restructurings		0.1		0.7			Various
Total Restructuring Charges	$	0.8	$	2.7

(1)

In March 2017, the Company announced plans to upgrade its production capability for compounded resins with the construction of a new state-of-the art compounding facility to replace its existing compounding facility in Terneuzen, The Netherlands. The new facility is expected to be operational by the end of 2018, with substantive production at the existing facility expected to cease by December 2018, followed by decommissioning activities in 2019. The Company expects to incur incremental accelerated depreciation charges of approximately $0.9 million through the end of 2018, as well as estimated employee termination benefit charges and decommissioning and other charges of approximately $0.9 million throughout 2019, the majority of which are expected to be paid throughout 2019.

(2)

In August 2016, the Company announced its plan to cease manufacturing activities at its latex binders manufacturing facility in Livorno, Italy. Production at the facility ceased in October 2016, followed by decommissioning activities which began in the fourth quarter of 2016. The Company does not expect to incur additional employee termination benefit charges related to this restructuring. The Company expects to incur additional decommissioning costs associated with this plant shutdown in 2018, the cost of which will be expensed as incurred.

Rollforward of Liability Balances

	Balance at						Balance at
	December 31, 2017		Expenses		Deductions(1)		March 31, 2018
Employee termination benefits	$	1.4	$	0.1	$	(0.6)	$	0.9
Contract terminations		0.6		—		—		0.6
Decommissioning and other		—		0.4		(0.4)		—
Total	$	2.0	$	0.5	$	(1.0)	$	1.5

(1)

Includes primarily payments made against the existing accrual, as well as immaterial impacts of foreign currency remeasurement.

.

Accumulated Other Comprehensive Income (Loss) (Tables)

3 Months Ended

Mar. 31, 2018

Shareholders' Equity.

Components of AOCI, Net of Income Taxes


	Cumulative		Pension & Other
	Translation		Postretirement Benefit		Cash Flow
Three Months Ended March 31, 2018 and 2017	Adjustments		Plans, Net		Hedges, Net		Total
Balance at December 31, 2017	$	(94.5)	$	(45.0)	$	(6.1)	$	(145.6)
Other comprehensive income (loss)		(2.1)		—		(1.0)		(3.1)
Amounts reclassified from AOCI to net income (1)		—		0.6		3.8		4.4
Balance at March 31, 2018	$	(96.6)	$	(44.4)	$	(3.3)	$	(144.3)

Balance as of December 31, 2016	$	(119.0)	$	(63.5)	$	12.3	$	(170.2)
Other comprehensive income (loss)		4.2		—		(2.3)		1.9
Amounts reclassified from AOCI to net income (1)		—		1.4		(2.5)		(1.1)
Balance as of March 31, 2017	$	(114.8)	$	(62.1)	$	7.5	$	(169.4)

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]

	Amount Reclassified from AOCI
AOCI Components	Three Months Ended March 31,				Statement of Operations
	2018		2017		Classification
Cash flow hedging items
Foreign exchange cash flow hedges	$	3.7	$	(2.5)	Cost of sales
Interest rate swaps		0.1		—	Interest expense, net
Total before tax		3.8		(2.5)
Tax effect		—		—	Provision for income taxes
Total, net of tax	$	3.8	$	(2.5)

Amortization of pension and other postretirement benefit plan items
Prior service credit	$	(0.2)	$	(0.4)	(a)
Net actuarial loss		1.1		1.6	(a)
Net settlement and curtailment loss		—		0.6	(a)
Total before tax		0.9		1.8
Tax effect		(0.3)		(0.4)	Provision for income taxes
Total, net of tax	$	0.6	$	1.4

(a)

These AOCI components are included in the computation of net periodic benefit costs (see Note 12).

Earnings Per Share (Tables)

3 Months Ended

Mar. 31, 2018

Earnings Per Share

Schedule of Earnings per Share Basic and Diluted


	Three Months Ended
	March 31,
(in millions, except per share data)	2018		2017
Earnings:
Net income	$	120.3	$	117.3
Shares:
Weighted average ordinary shares outstanding		43.4		44.1
Dilutive effect of RSUs, option awards, and PSUs*		1.0		1.2
Diluted weighted average ordinary shares outstanding		44.4		45.3
Income per share:
Income per share—basic	$	2.77	$	2.66
Income per share—diluted	$	2.71	$	2.59

* Refer to Note 13 for discussion of RSUs, option awards, and PSUs granted to certain Company directors and employees. The number of anti-dilutive shares that have been excluded in the computation of diluted earnings per share for the three months ended March 31, 2018 and 2017 were 0.2 million and 0.2 million, respectively.

Recent Accounting Guidance - Revenue Recognition (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Recent Accounting Guidance
Cumulative effect of initially applying the new revenue standard to retained earnings	$ 632.4	$ 527.9

Recent Accounting Guidance - Other (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest expense, net	$ 14.9	$ 18.2
Cost of sales	946.4	905.5
Selling, general and administrative expenses	64.4	$ 59.6
Accounting Standards Update 2017-07 [Member] \| Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of sales	(1.2)
Selling, general and administrative expenses	$ (0.8)

Net Sales (Details) - USD ($) $ in Millions	3 Months Ended
Net Sales (Details) - USD ($) $ in Millions	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue, Practical Expedient, Incremental Cost of Obtaining Contract [true/false]	true
Revenue, Practical Expedient, Financing Component [true/false]	true
Revenue, Practical Expedient, Remaining Performance Obligation [true/false]	true
Net sales	$ 1,121.6
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		$ 1,104.5
Minimum
Disaggregation of Revenue [Line Items]
Product sales payment terms	10 days
Maximum
Disaggregation of Revenue [Line Items]
Product sales payment terms	90 days
Weighted Average [Member]
Disaggregation of Revenue [Line Items]
Product sales payment terms	50 days
Latex Binders Segment
Disaggregation of Revenue [Line Items]
Net sales	$ 255.3
Latex Binders Segment \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		288.9
Synthetic Rubber Segment
Disaggregation of Revenue [Line Items]
Net sales	149.2
Synthetic Rubber Segment \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		163.4
Performance Plastics Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	402.9
Performance Plastics Segment [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		336.9
Polystyrene [Member]
Disaggregation of Revenue [Line Items]
Net sales	239.6
Polystyrene [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		228.4
Feedstocks [Member]
Disaggregation of Revenue [Line Items]
Net sales	74.6
Feedstocks [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		86.9
United States [Member]
Disaggregation of Revenue [Line Items]
Net sales	152.3
United States [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		162.8
United States [Member] \| Latex Binders Segment
Disaggregation of Revenue [Line Items]
Net sales	64.3
United States [Member] \| Latex Binders Segment \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		76.0
United States [Member] \| Performance Plastics Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	84.1
United States [Member] \| Performance Plastics Segment [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		82.8
United States [Member] \| Polystyrene [Member]
Disaggregation of Revenue [Line Items]
Net sales	0.2
United States [Member] \| Polystyrene [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		0.2
United States [Member] \| Feedstocks [Member]
Disaggregation of Revenue [Line Items]
Net sales	3.7
United States [Member] \| Feedstocks [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		3.8
Europe [Member]
Disaggregation of Revenue [Line Items]
Net sales	717.8
Europe [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		657.1
Europe [Member] \| Latex Binders Segment
Disaggregation of Revenue [Line Items]
Net sales	113.3
Europe [Member] \| Latex Binders Segment \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		119.5
Europe [Member] \| Synthetic Rubber Segment
Disaggregation of Revenue [Line Items]
Net sales	149.2
Europe [Member] \| Synthetic Rubber Segment \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		163.4
Europe [Member] \| Performance Plastics Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	249.2
Europe [Member] \| Performance Plastics Segment [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		199.4
Europe [Member] \| Polystyrene [Member]
Disaggregation of Revenue [Line Items]
Net sales	148.2
Europe [Member] \| Polystyrene [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		140.1
Europe [Member] \| Feedstocks [Member]
Disaggregation of Revenue [Line Items]
Net sales	57.9
Europe [Member] \| Feedstocks [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		34.7
Asia-Pacific [Member]
Disaggregation of Revenue [Line Items]
Net sales	225.8
Asia-Pacific [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		258.2
Asia-Pacific [Member] \| Latex Binders Segment
Disaggregation of Revenue [Line Items]
Net sales	74.3
Asia-Pacific [Member] \| Latex Binders Segment \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		89.0
Asia-Pacific [Member] \| Performance Plastics Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	47.3
Asia-Pacific [Member] \| Performance Plastics Segment [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		32.7
Asia-Pacific [Member] \| Polystyrene [Member]
Disaggregation of Revenue [Line Items]
Net sales	91.2
Asia-Pacific [Member] \| Polystyrene [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		88.1
Asia-Pacific [Member] \| Feedstocks [Member]
Disaggregation of Revenue [Line Items]
Net sales	13.0
Asia-Pacific [Member] \| Feedstocks [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		48.4
Rest of World [Member]
Disaggregation of Revenue [Line Items]
Net sales	25.7
Rest of World [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		26.4
Rest of World [Member] \| Latex Binders Segment
Disaggregation of Revenue [Line Items]
Net sales	3.4
Rest of World [Member] \| Latex Binders Segment \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		4.4
Rest of World [Member] \| Performance Plastics Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 22.3
Rest of World [Member] \| Performance Plastics Segment [Member] \| Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Net sales		$ 22.0

Investments in Unconsolidated Affiliates - Summarized Financial Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Summarized Financial Information, Net Income
Sales	$ 486.6	$ 433.9
Gross profit	95.2	20.6
Net income	$ 85.7	$ 6.3

Investments in Unconsolidated Affiliates (Details) - USD ($) $ in Millions		3 Months Ended
	Jan. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Investments in Unconsolidated Affiliates
Equity in earnings (losses) of unconsolidated affiliates		$ 45.5	$ 19.3
Investments in unconsolidated affiliates		168.1	160.6	$ 152.5
Americas Styrenics
Investments in Unconsolidated Affiliates
Investments in unconsolidated affiliates		168.1		152.5
Investment in unconsolidated affiliates-difference between carrying amount and underlying equity		$ 43.8		$ 46.4
Percentage of ownership underlying net assets		50.00%		50.00%
Amortized weighted average remaining useful life		P2Y7M6D
Dividends received from operating activities		$ 30.0	7.5
Sumika Styron Polycarbonate
Investments in Unconsolidated Affiliates
Investments in unconsolidated affiliates				$ 0.0
Percentage of ownership underlying net assets	50.00%
Sales proceeds	$ 42.1
Gain on sale			9.3
Dividends received from operating and investing activities			$ 9.8

Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Inventories
Finished goods	$ 285.6	$ 250.9
Raw materials and semi-finished goods	265.1	226.7
Supplies	37.6	32.8
Total	$ 588.3	$ 510.4

Debt - Schedule of Debt (Details) € in Millions, $ in Millions		3 Months Ended
	Sep. 06, 2017	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Aug. 31, 2017 EUR (€)	Aug. 29, 2017 USD ($)
Debt Instruments
Carrying amount		$ 1,197.9	$ 1,199.7
Unamortized deferred financing fees		(26.9)	(27.7)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent		1,171.0	1,172.0
Less: current portion		(7.0)	(7.0)
Total long-term debt, net of unamortized deferred financing fees		1,164.0	1,165.0
2022 Revolving Facility
Debt Instruments
Funds available for borrowings		359.9
Letters of credit, amount outstanding		$ 15.1
Commitment fee (as a percent)		0.375%
Maximum borrowing capacity		$ 375.0
2024 Term Loan B
Debt Instruments
Interest rate		4.377%
Carrying amount		$ 696.5	698.3
Unamortized deferred financing fees		(17.8)	(18.3)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent		678.7	680.0
Less: current portion		$ (7.0)
2024 Term Loan B \| LIBOR [Member]
Debt Instruments
Debt instrument, margin rate	2.50%	2.50%
Variable rate floor (as a percent)	0.00%	0.00%
2025 Senior Notes
Debt Instruments
Interest rate		5.375%			5.375%
Carrying amount		$ 500.0	500.0
Unamortized deferred financing fees		(9.1)	(9.4)
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent		490.9	490.6		$ 500.0
Accounts Receivable Securitization Facility [Member]
Debt Instruments
Carrying amount		0.0	0.0
Unamortized deferred financing fees		0.0	0.0
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent		$ 0.0	0.0
Commitment fee (as a percent)		1.00%
Maximum borrowing capacity		$ 150.0
Accounts Receivable Securitization Facility [Member] \| Base Rate [Member]
Debt Instruments
Interest rate		1.95%
Other Indebtedness [Member]
Debt Instruments
Carrying amount		$ 1.4	1.4
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent		$ 1.4	$ 1.4
Euro Notes
Debt Instruments
Total Debt, Less Unamortized Deferred Financing Fees, Current and Noncurrent \| €				€ 375.0

Goodwill and Intangible Assets (Details) $ in Millions	3 Months Ended
Goodwill and Intangible Assets (Details) $ in Millions	Mar. 31, 2018 USD ($)
Goodwill [Roll Forward]
Beginning Balance	$ 72.5
Foreign currency impact	1.7
Ending Balance	74.2
Latex Binders Segment
Goodwill [Roll Forward]
Beginning Balance	16.5
Foreign currency impact	0.4
Ending Balance	16.9
Synthetic Rubber Segment
Goodwill [Roll Forward]
Beginning Balance	11.7
Foreign currency impact	0.3
Ending Balance	12.0
Performance Plastics Segment [Member]
Goodwill [Roll Forward]
Beginning Balance	39.6
Foreign currency impact	0.9
Ending Balance	40.5
Polystyrene [Member]
Goodwill [Roll Forward]
Beginning Balance	4.7
Foreign currency impact	0.1
Ending Balance	$ 4.8

Derivative Instruments (Details) € in Millions, $ in Millions			3 Months Ended
	Sep. 06, 2017	Sep. 01, 2017 USD ($)	Mar. 31, 2018 USD ($) item	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Sep. 01, 2017 EUR (€)	Aug. 31, 2017 EUR (€)	Aug. 29, 2017 USD ($)
Derivative Instruments
Total debt			$ 1,171.0		$ 1,172.0
Information regarding changes in fair value of derivatives
Foreign exchange transaction gains (losses)			10.4	$ 0.6
Ineffectiveness related to derivatives designated as hedges			0.0
Reclassification expected during next 12 months			(11.5)
Net Investment Hedges
Information regarding changes in fair value of derivatives
Gain (Loss) Recognized in AOCI on Balance Sheet			(20.4)	(5.0)
Not Designated as Hedging Instruments - Economic
Information regarding changes in fair value of derivatives
Gain (Loss) Recognized in Statement of Operations			(5.3)	(1.7)
Designated as Hedging Instrument \| Cash Flow Hedges
Information regarding changes in fair value of derivatives
Gain (Loss) Recognized in AOCI on Balance Sheet			2.8	(4.8)
Gain (Loss) Recognized in Statement of Operations			$ (3.8)	2.5
Foreign Exchange Forward Contracts
Derivative Instruments
Derivative term			2 months
Foreign Exchange Forward Contracts \| Not Designated as Hedging Instruments - Economic
Derivative Instruments
Derivative contracts, notional amount			$ 334.7
Foreign Exchange Forward Contracts \| Designated as Hedging Instrument
Derivative Instruments
Derivative contracts, notional amount			$ 162.0
Derivative term			9 months
Number of subsidiaries participating \| item			1
Cross Currency Swap \| Net Investment Hedges
Derivative Instruments
Derivative contracts, notional amount \| €						€ 420.0
Derivative term		5 years
Cross currency swap weighted average interest rate (as a percent)		3.45%
Amount hedged		$ 500.0
Cumulative translation adjustment, net of tax			$ 38.0
Information regarding changes in fair value of derivatives
Gain (Loss) Recognized in AOCI on Balance Sheet			(20.4)
Debt Instrument Hedge \| Net Investment Hedges
Derivative Instruments
Total debt \| €							€ 280.0
Cumulative translation adjustment, net of tax					24.1
Information regarding changes in fair value of derivatives
Gain (Loss) Recognized in AOCI on Balance Sheet				(5.0)
Interest Rate Swap
Derivative Instruments
Derivative contracts, notional amount			$ 200.0
Derivative term			5 years
Fixed interest rate per agreement (as a percent)			1.81%
LIBOR rate at end of period (as a percent)			1.88%
Cost of Sales \| Foreign Exchange Forward Contracts \| Designated as Hedging Instrument \| Cash Flow Hedges
Information regarding changes in fair value of derivatives
Gain (Loss) Recognized in AOCI on Balance Sheet			$ (0.5)	(4.8)
Gain (Loss) Recognized in Statement of Operations			(3.7)	2.5
Interest Expense, Net \| Interest Rate Swap \| Designated as Hedging Instrument \| Cash Flow Hedges
Information regarding changes in fair value of derivatives
Gain (Loss) Recognized in AOCI on Balance Sheet			3.3
Gain (Loss) Recognized in Statement of Operations			(0.1)
Other Expense (Income), Net \| Foreign Exchange Forward Contracts \| Not Designated as Hedging Instruments - Economic
Information regarding changes in fair value of derivatives
Gain (Loss) Recognized in Statement of Operations			(5.3)	$ (1.7)
Euro Notes
Derivative Instruments
Total debt \| €							€ 375.0
2025 Senior Notes
Derivative Instruments
Total debt			$ 490.9		490.6			$ 500.0
Interest rate			5.375%					5.375%
2024 Term Loan B
Derivative Instruments
Total debt			$ 678.7		$ 680.0
Interest rate			4.377%
2024 Term Loan B \| LIBOR [Member]
Derivative Instruments
Debt instrument, margin rate	2.50%		2.50%
Variable rate floor (as a percent)	0.00%		0.00%
Euro [Member] \| Foreign Exchange Forward Contracts \| Sell \| Not Designated as Hedging Instruments - Economic
Derivative Instruments
Derivative contracts, notional amount			$ 129.4
Chinese Yuan [Member] \| Foreign Exchange Forward Contracts \| Sell \| Not Designated as Hedging Instruments - Economic
Derivative Instruments
Derivative contracts, notional amount			78.2
Swiss Franc [Member] \| Foreign Exchange Forward Contracts \| Buy \| Not Designated as Hedging Instruments - Economic
Derivative Instruments
Derivative contracts, notional amount			54.6
Taiwan, New Dollars \| Foreign Exchange Forward Contracts \| Buy \| Not Designated as Hedging Instruments - Economic
Derivative Instruments
Derivative contracts, notional amount			14.4
Indonesian Rupiah [Member] \| Foreign Exchange Forward Contracts \| Sell \| Not Designated as Hedging Instruments - Economic
Derivative Instruments
Derivative contracts, notional amount			$ 14.0

Derivative Instruments - Financial Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Financial Assets and Liabilities
Derivative assets	$ 16.9	$ 13.9
Derivative liabilities	63.2	42.0
Gross Amounts of Recognized Assets, Current	11.4	11.5
Gross Amounts of Offset in the Consolidated Balance Sheet, Current	(0.1)	(0.6)
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Current	11.3	10.9
Gross Amounts of Recognized Assets, Noncurrent	5.6	3.0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Noncurrent	5.6	3.0
Gross Amounts of Recognized Liabilities, Current	15.0	14.3
Gross Amounts of Offset in the Consolidated Balance Sheet, Current	(0.1)	(0.6)
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Current	14.9	13.7
Gross Amounts of Recognized Liiabilities, Noncurrent	48.3	28.3
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Noncurrent	48.3	28.3
Accounts Receivable
Derivatives, Financial Assets and Liabilities
Derivative assets	11.3	10.9
Deferred Charges and Other Assets
Derivatives, Financial Assets and Liabilities
Derivative assets	5.6	3.0
Accounts Payable
Derivatives, Financial Assets and Liabilities
Derivative liabilities	14.9	13.7
Other Noncurrent Obligations
Derivatives, Financial Assets and Liabilities
Derivative liabilities	48.3	28.3
Foreign Exchange Forward Contracts \| Not Designated as Hedging Instruments - Economic
Derivatives, Financial Assets and Liabilities
Derivative assets	0.3	0.1
Derivative liabilities	2.8	2.5
Foreign Exchange Forward Contracts \| Not Designated as Hedging Instruments - Economic \| Accounts Receivable
Derivatives, Financial Assets and Liabilities
Derivative assets	0.3	0.1
Foreign Exchange Forward Contracts \| Not Designated as Hedging Instruments - Economic \| Accounts Payable
Derivatives, Financial Assets and Liabilities
Derivative liabilities	2.8	2.5
Foreign Exchange Forward Contracts \| Designated as Hedging Instrument
Derivatives, Financial Assets and Liabilities
Derivative liabilities	12.1	11.1
Foreign Exchange Forward Contracts \| Designated as Hedging Instrument \| Accounts Payable
Derivatives, Financial Assets and Liabilities
Derivative liabilities	12.1	11.1
Interest Rate Swap
Derivatives, Financial Assets and Liabilities
Derivative assets	6.2	3.0
Derivative liabilities		0.1
Interest Rate Swap \| Accounts Receivable
Derivatives, Financial Assets and Liabilities
Derivative assets	0.6
Interest Rate Swap \| Deferred Charges and Other Assets
Derivatives, Financial Assets and Liabilities
Derivative assets	5.6	3.0
Interest Rate Swap \| Accounts Payable
Derivatives, Financial Assets and Liabilities
Derivative liabilities		0.1
Cross Currency Swap
Derivatives, Financial Assets and Liabilities
Derivative assets	10.4	10.8
Derivative liabilities	48.3	28.3
Cross Currency Swap \| Accounts Receivable
Derivatives, Financial Assets and Liabilities
Derivative assets	10.4	10.8
Cross Currency Swap \| Other Noncurrent Obligations
Derivatives, Financial Assets and Liabilities
Derivative liabilities	$ 48.3	$ 28.3

Fair Value Measurements - Assets and Liabilities at Fair Value, Recurring (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value Measurements
Assets at fair value	$ 16.9	$ 13.9
Liabilities at fair value	(63.2)	(42.0)
Interest Rate Swap
Fair Value Measurements
Assets at fair value	6.2	3.0
Liabilities at fair value		(0.1)
Cross Currency Swap
Fair Value Measurements
Assets at fair value	10.4	10.8
Liabilities at fair value	(48.3)	(28.3)
Designated as Hedging Instrument \| Foreign Exchange Forward Contracts
Fair Value Measurements
Liabilities at fair value	(12.1)	(11.1)
Not Designated as Hedging Instruments - Economic \| Foreign Exchange Forward Contracts
Fair Value Measurements
Assets at fair value	0.3	0.1
Liabilities at fair value	(2.8)	(2.5)
Recurring
Fair Value Measurements
Total fair value	(46.3)	(28.1)
Recurring \| Interest Rate Swap
Fair Value Measurements
Assets at fair value	6.2	3.0
Liabilities at fair value		(0.1)
Recurring \| Cross Currency Swap
Fair Value Measurements
Assets at fair value	10.4	10.8
Liabilities at fair value	(48.3)	(28.3)
Recurring \| Significant Other Observable Inputs (Level 2)
Fair Value Measurements
Total fair value	(46.3)	(28.1)
Recurring \| Significant Other Observable Inputs (Level 2) \| Interest Rate Swap
Fair Value Measurements
Assets at fair value	6.2	3.0
Liabilities at fair value		(0.1)
Recurring \| Significant Other Observable Inputs (Level 2) \| Cross Currency Swap
Fair Value Measurements
Assets at fair value	10.4	10.8
Liabilities at fair value	(48.3)	(28.3)
Recurring \| Designated as Hedging Instrument \| Foreign Exchange Forward Contracts
Fair Value Measurements
Liabilities at fair value	(12.1)	(11.1)
Recurring \| Designated as Hedging Instrument \| Significant Other Observable Inputs (Level 2) \| Foreign Exchange Forward Contracts
Fair Value Measurements
Liabilities at fair value	(12.1)	(11.1)
Recurring \| Not Designated as Hedging Instruments - Economic \| Foreign Exchange Forward Contracts
Fair Value Measurements
Assets at fair value	0.3	0.1
Liabilities at fair value	(2.8)	(2.5)
Recurring \| Not Designated as Hedging Instruments - Economic \| Significant Other Observable Inputs (Level 2) \| Foreign Exchange Forward Contracts
Fair Value Measurements
Assets at fair value	0.3	0.1
Liabilities at fair value	$ (2.8)	$ (2.5)

Fair Value Measurements - Items not at Fair Value (Details) - Significant Other Observable Inputs (Level 2) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value of Debt Instruments
Total fair value of long term debt	$ 1,196.9	$ 1,224.5
2025 Senior Notes
Fair Value of Debt Instruments
Total fair value of long term debt	495.2	518.8
2024 Term Loan B
Fair Value of Debt Instruments
Total fair value of long term debt	$ 701.7	$ 705.7

Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Provision for Income Taxes
Effective tax rate	17.10%	20.00%
Provision for income taxes	$ 24.9	$ 29.3
Sumika Styron Polycarbonate
Provision for Income Taxes
Gain on sale		$ 9.3

Commitments and Contingencies (Details)	Mar. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure
Accrued obligations for environmental remediation and restoration costs \| $	$ 0	$ 0
Environmental claims asserted \| item	0

Commitments and Contingencies - Purchase Commitments (Details)	3 Months Ended
	Mar. 31, 2018
Maximum
Loss Contingencies [Line Items]
Purchase commitment period	4 years
Minimum
Loss Contingencies [Line Items]
Purchase commitment period	1 year

Pension Plans and Other Postretirement Benefits - Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Pension Plans
Net periodic benefit cost
Service cost	$ 3.1	$ 4.6
Interest cost	1.3	1.1
Expected return on plan assets	(0.6)	(0.4)
Amortization of prior service cost (credit)	(0.3)	(0.5)
Amortization of net (gain) loss	1.0	1.4
Settlement and curtailment gain		0.1
Net periodic benefit cost	4.5	6.3
Settlement and curtailment gain	0.5
Defined benefit curtailment gain	0.4
Amounts recognized in other comprehensive income (loss)
Net periodic benefit cost	4.5	6.3
Other Postretirement Plans
Net periodic benefit cost
Service cost		0.1
Interest cost	0.1	0.1
Net periodic benefit cost	0.1	0.2
Amounts recognized in other comprehensive income (loss)
Net periodic benefit cost	$ 0.1	$ 0.2

Pension Plans and Other Postretirement Benefits - Net Amounts Recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Net amounts recognized in the balance sheets at December 31
Noncurrent liabilities	$ (195.2)	$ (188.7)
Cash contributions and benefit payments to unfunded plans	2.0
Expected contributions, remainder of current year	$ 4.5

Stock-Based Compensation - Summary of Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 5.5	$ 4.7
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2.2	1.9
Unrecognized compensation cost	$ 14.9
Weighted-average period of recognition	2 years 2 months 12 days
Option Awards
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2.8	2.6
Unrecognized compensation cost, options	$ 2.9
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]
Stock-based compensation expense	$ 0.5	$ 0.2
Unrecognized compensation cost	$ 6.7
Weighted-average period of recognition	2 years 6 months

Stock-Based Compensation - RSUs (Details) - Restricted Stock Units	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Other-than-Options, Shares Activity
Granted, Shares \| shares	97,676
Other-than-Options, FV Activity
Granted, Weighted-Average Grant Date Fair Value per Share \| $ / shares	$ 81.20

Stock-Based Compensation - Options and PSUs (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Options, Additional Disclosures
Proceeds from exercise of option awards	$ 1.9	$ 3.4
Option Awards
Options Outstanding Roll Forward
Granted, Options	202,963
Options, Additional Disclosures
Unrecognized compensation cost, options	$ 2.9
Fair Value Assumptions
Expected term (in years)	5 years 6 months
Expected volatility	32.00%
Risk-free interest rate	2.71%
Dividend yield	2.00%
Options granted, Weighted average grant date fair value	$ 22.29
Performance Share Units
Fair Value Assumptions
Expected term (in years)	3 years
Expected volatility	36.00%
Risk-free interest rate	2.42%
Share Price	$ 81.20
Other-than-Options, Shares Activity
Granted, Shares	50,289
Other-than-Options, FV Activity
Granted, Weighted-Average Grant Date Fair Value per Share	$ 88.51

Acquisitions and Divestitures - Acquisition (Details) - API Applicazioni Plastiche Industriali S.p.A. [Member] - USD ($) $ in Millions		3 Months Ended
	Jul. 10, 2017	Mar. 31, 2018
Business Acquisition [Line Items]
Equity interest acquired	100.00%
Gross purchase price	$ 90.6
Cash acquired	8.4
Purchase price, net of cash acquired	$ 82.3
Changes to purchase price allocation		$ 0.0
Transaction costs		$ 0.3

Segments - Reconciliation of Segment Reporting to Consolidated (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) division segment	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)	Jan. 31, 2017
Segment Reporting Information [Line Items]
Number of divisions \| division	2
Number of reportable segments \| segment	6
Number of segments unchanged from former model \| segment	4
Sales to external customers	$ 1,121.6	$ 1,104.5
Equity in earnings (losses) of unconsolidated affiliates	45.5	19.3
Adjusted EBITDA	215.1	209.3
Investment in unconsolidated affiliates	168.1	160.6	$ 152.5
Depreciation and amortization	$ 31.9	24.7
Americas Styrenics
Segment Reporting Information [Line Items]
Percentage of ownership underlying net assets	50.00%		50.00%
Investment in unconsolidated affiliates	$ 168.1		$ 152.5
Sumika Styron Polycarbonate
Segment Reporting Information [Line Items]
Percentage of ownership underlying net assets				50.00%
Investment in unconsolidated affiliates			$ 0.0
Corporate Unallocated [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	2.3	2.1
Latex Binders Segment
Segment Reporting Information [Line Items]
Sales to external customers	255.3	288.9
Adjusted EBITDA	27.5	36.8
Depreciation and amortization	6.1	5.7
Synthetic Rubber Segment
Segment Reporting Information [Line Items]
Sales to external customers	149.2	163.4
Adjusted EBITDA	25.5	46.3
Depreciation and amortization	11.2	8.4
Performance Plastics Segment [Member]
Segment Reporting Information [Line Items]
Sales to external customers	402.9	336.9
Equity in earnings (losses) of unconsolidated affiliates		0.8
Adjusted EBITDA	65.5	52.2
Depreciation and amortization	6.4	4.0
Polystyrene [Member]
Segment Reporting Information [Line Items]
Sales to external customers	239.6	228.4
Adjusted EBITDA	9.6	13.6
Depreciation and amortization	2.9	2.0
Basic Plastics Segment [Member] \| Sumika Styron Polycarbonate
Segment Reporting Information [Line Items]
Percentage of ownership underlying net assets				50.00%
Feedstocks [Member]
Segment Reporting Information [Line Items]
Sales to external customers	74.6	86.9
Adjusted EBITDA	41.5	41.9
Depreciation and amortization	3.0	2.5
Americas Styrenics [Member]
Segment Reporting Information [Line Items]
Equity in earnings (losses) of unconsolidated affiliates	45.5	18.5
Adjusted EBITDA	45.5	18.5
Investment in unconsolidated affiliates	$ 168.1	$ 160.6
Americas Styrenics [Member] \| Americas Styrenics
Segment Reporting Information [Line Items]
Percentage of ownership underlying net assets	50.00%

Segments - Recon. of Net Income to Segment Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Income before income taxes	$ 145.2	$ 146.6
Interest expense, net	(14.9)	(18.2)
Depreciation and amortization	31.9	24.7
Corporate Unallocated	20.1	27.6
Adjusted EBITDA addbacks	3.0	(7.8)
Adjusted EBITDA	215.1	209.3
Net loss (gain) on disposition of businesses and assets	(0.5)	(9.9)
Restructuring and other charges	0.5	2.1
Acquisition transactions and integration costs	0.3
Other items	2.7
Operating Segments [Member]
Segment Reporting Information [Line Items]
Income before income taxes	145.2	146.6
Corporate Unallocated [Member]
Segment Reporting Information [Line Items]
Interest expense, net	(14.9)	(18.2)
Depreciation and amortization	$ 2.3	$ 2.1

Restructuring (Details) - USD ($) $ in Millions	3 Months Ended
Restructuring (Details) - USD ($) $ in Millions	Mar. 31, 2018	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 0.8	$ 2.7
Restructuring Reserve [Roll Forward]
Accrued charges/Balance at beginning of period	2.0
Expenses	0.5
Payments/Deductions	(1.0)
Accrued charges/Balance at end of period	1.5
Terneuzen Plant Modernization
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.4	1.2
Cumulative life-to-date charges	4.4
Livorno Plant Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.3	0.8
Cumulative life-to-date charges	23.3
Other Restructurings
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.1	0.7
Asset Impairment And Accelerated Depreciation [Member] \| Terneuzen Plant Modernization
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.3	0.6
Cumulative life-to-date charges	2.3
Asset Impairment And Accelerated Depreciation [Member] \| Livorno Plant Restructuring
Restructuring Cost and Reserve [Line Items]
Cumulative life-to-date charges	14.3
Accelerated Depreciation On Related Assets [Member] \| Terneuzen Plant Modernization
Restructuring Reserve [Roll Forward]
Expected restructuring charges	0.9
Employee Termination Benefit Charges
Restructuring Reserve [Roll Forward]
Accrued charges/Balance at beginning of period	1.4
Expenses	0.1
Payments/Deductions	(0.6)
Accrued charges/Balance at end of period	0.9
Employee Termination Benefit Charges \| Terneuzen Plant Modernization
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.1
Cumulative life-to-date charges	0.7
Employee Termination Benefit Charges \| Livorno Plant Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.2
Cumulative life-to-date charges	5.4
Contract Termination
Restructuring Reserve [Roll Forward]
Accrued charges/Balance at beginning of period	0.6
Accrued charges/Balance at end of period	0.6
Contract Termination \| Terneuzen Plant Modernization
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.6
Cumulative life-to-date charges	0.6
Contract Termination \| Livorno Plant Restructuring
Restructuring Cost and Reserve [Line Items]
Cumulative life-to-date charges	0.3
Decommissioning and Other Charges
Restructuring Reserve [Roll Forward]
Expenses	0.4
Payments/Deductions	(0.4)
Decommissioning and Other Charges \| Terneuzen Plant Modernization
Restructuring Cost and Reserve [Line Items]
Cumulative life-to-date charges	0.8
Restructuring Reserve [Roll Forward]
Expected restructuring charges	0.9
Decommissioning and Other Charges \| Livorno Plant Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.3	$ 0.6
Cumulative life-to-date charges	$ 3.3

Accumulated Other Comprehensive Income (Loss) - Components (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	$ 674.8	$ 447.7
Balance at end of period	755.7	536.7
Cumulative Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(94.5)	(119.0)
Other comprehensive income (loss)	(2.1)	4.2
Balance at end of period	(96.6)	(114.8)
Pension and Other Postretirement Benefit Plans, Net
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(45.0)	(63.5)
Amounts reclassified from AOCI to net income	0.6	1.4
Balance at end of period	(44.4)	(62.1)
Accumulated Gain Loss from Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(6.1)	12.3
Other comprehensive income (loss)	(1.0)	(2.3)
Amounts reclassified from AOCI to net income	3.8	(2.5)
Balance at end of period	(3.3)	7.5
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(145.6)	(170.2)
Other comprehensive income (loss)	(3.1)	1.9
Amounts reclassified from AOCI to net income	4.4	(1.1)
Balance at end of period	$ (144.3)	$ (169.4)

Accumulated Other Comprehensive Income (Loss) - Reclassification (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net	$ 14.9	$ 18.2
Income before income taxes	(145.2)	(146.6)
Provision for (benefit from) income taxes	24.9	29.3
Net income	(120.3)	(117.3)
Pension and Other Postretirement Benefit Plans, Net \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Settlement and curtailment gain		0.6
Income before income taxes	0.9	1.8
Provision for (benefit from) income taxes	(0.3)	(0.4)
Net income	0.6	1.4
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credit	(0.2)	(0.4)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net actuarial loss	1.1	1.6
Accumulated Gain Loss from Cash Flow Hedges \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of Sales	3.7	(2.5)
Interest expense, net	0.1
Income before income taxes	3.8	(2.5)
Net income	$ 3.8	$ (2.5)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings:
Net income (loss)	$ 120.3	$ 117.3
Shares:
Weighted average ordinary shares outstanding	43.4	44.1
Dilutive effect of RSUs and option awards	1.0	1.2
Diluted weighted average ordinary shares outstanding	44.4	45.3
Income (loss) per share:
Income per share- basic	$ 2.77	$ 2.66
Income per share- diluted	$ 2.71	$ 2.59
Anti-dilutive shares excluded	0.2	0.2