Document and Entity Information	6 Months Ended
Document and Entity Information	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	Orion Engineered Carbons S.A.
Entity Central Index Key	0001609804
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2018
Document Type	6-K
Document Fiscal Period Focus	Q2
Amendment Flag	false
Document Period End Date	Jun. 30, 2018

Interim Condensed Consolidated Income Statements - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Profit or loss [abstract]
Revenue	$ 391,586	$ 329,613	$ 798,285	$ 653,678
Cost of sales	(278,813)	(236,734)	(573,109)	(465,261)
Gross profit	112,773	92,879	225,176	188,417
Selling expenses	(35,732)	(32,705)	(73,600)	(63,450)
Research and development costs	(4,644)	(4,456)	(9,705)	(8,644)
General and administrative expenses	(18,426)	(18,209)	(39,469)	(38,346)
Other operating income	296	2,127	459	2,274
Other operating expenses	(1,561)	(1,097)	(3,556)	(4,290)
Restructuring income	40,253	0	40,253	0
Restructuring expenses	(10,502)	(319)	(11,768)	(722)
Restructuring income/(expenses), net	29,751	(319)	28,485	(722)
Earnings before taxes and finance income/costs (operating result (EBIT))	82,457	38,220	127,790	75,239
Finance income	19,123	6,245	19,978	20,083
Finance costs	(28,475)	(17,147)	(37,420)	(41,355)
Share of profit or loss of joint ventures	144	133	293	262
Financial result	(9,208)	(10,769)	(17,149)	(21,010)
Profit before income taxes	73,249	27,451	110,641	54,229
Income taxes	(20,558)	(9,023)	(33,722)	(18,986)
Profit for the period	$ 52,691	$ 18,428	$ 76,919	$ 35,243
Earnings per share (USD per share), basic	$ 0.88	$ 0.31	$ 1.29	$ 0.59
Weighted average shares, basic (in thousand of shares)	59,590	59,320	59,456	59,320
Earnings per share (USD per share), diluted	$ 0.87	$ 0.30	$ 1.26	$ 0.58
Weighted average shares, diluted (in thousand of shares)	60,743	60,460	60,866	60,462

Interim Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of comprehensive income [abstract]
Profit for the period	$ 52,691	$ 18,428	$ 76,919	$ 35,243
Exchange differences on translation of foreign operations
Change in unrealized gains/(losses)	(6,504)	(18,303)	(12,549)	(7,205)
Income tax effects	(881)	(365)	(872)	(133)
Unrealized net gains/(losses) on net investments in a foreign operation
Change in unrealized gains/(losses)	(4,875)	10,690	(12)	12,914
Income tax effects	1,623	(3,455)	4	(4,174)
Unrealized net gains/(losses) on cash flow hedges
Change in unrealized gains/(losses)	(3,474)	21	(2,347)	(1,015)
Income tax effects	964	(5)	790	223
Net other comprehensive income to be reclassified to profit or loss in subsequent periods	(13,147)	(11,417)	(14,986)	610
Actuarial gains (losses) on defined benefit plans
Change in unrealized gains/(losses)	2,094	(256)	207	(833)
Income tax effects	(661)	109	(54)	283
Net other comprehensive income not to be reclassified to profit or loss in subsequent periods	1,433	(147)	153	(550)
Other comprehensive income, net of tax	(11,714)	(11,564)	(14,833)	60
Total comprehensive income, net of tax all attributable to equity holders of the parent	$ 40,977	$ 6,864	$ 62,086	$ 35,303

Interim Condensed Consolidated Statements of Financial Position - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Non-current assets
Goodwill	$ 56,555	$ 58,180
Other intangible assets	60,650	70,722
Property, plant and equipment	429,603	462,129
Investment in joint ventures	5,711	5,585
Other financial assets	3,175	3,564
Other assets	3,499	3,883
Deferred tax assets	56,510	43,546
Total Non-current assets	615,703	647,609
Current assets
Inventories	175,228	159,334
Trade receivables	277,621	234,273
Other financial assets	6,872	3,890
Other assets	28,725	35,038
Income tax receivables	14,983	16,377
Cash and cash equivalents	73,453	72,284
Total Current assets	576,882	521,196
Total Assets	1,192,585	1,168,805
Equity
Subscribed capital	84,254	83,770
Treasury shares	(3,757)	(3,773)
Reserves	(26,610)	(55,403)
Profit for the period	76,919	75,262
Total Equity	130,806	99,856
Non-current liabilities
Pension provisions	64,714	65,390
Other provisions	11,576	13,344
Financial liabilities	664,441	680,699
Other liabilities	66	6
Deferred tax liabilities	33,931	25,121
Total Non-current liabilities	774,728	784,560
Current liabilities
Other provisions	56,746	59,471
Trade payables	164,180	169,624
Other financial liabilities	8,872	7,013
Income tax liabilities	35,741	15,539
Other liabilities	21,512	32,742
Current liabilities	287,051	284,389
Equity and liabilities	$ 1,192,585	$ 1,168,805

Interim Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of cash flows [abstract]
Profit for the period	$ 52,691	$ 18,428	$ 76,919	$ 35,243
Income taxes	20,558	9,023	33,722	18,986
Profit before income taxes	73,249	27,451	110,641	54,229
Depreciation and amortization of intangible assets and property, plant and equipment	24,239	24,035	49,029	46,277
Gain on sale of property, plant and equipment	(40,253)	0	(40,253)	0
Other non-cash expenses/(income)	2,124	1,402	5,656	3,421
(Increase) in trade receivables	(4,935)	(4,027)	(53,039)	(20,499)
(Increase) in inventories	(21,763)	(2,996)	(21,774)	(15,655)
Increase in trade payables	594	6,926	12,552	11,436
Decrease in provisions	10,693	(1,663)	(3,179)	(21,560)
Increase in other assets and liabilities that cannot be allocated to investing or financing activities	(15,861)	(4,582)	(8,838)	582
Finance income	(19,123)	(11,743)	(19,978)	(20,083)
Finance costs	28,475	22,645	37,420	41,355
Cash paid for income taxes	(13,288)	(8,905)	(16,869)	(12,388)
Other cash paid	(4,741)	0	(4,741)	0
Cash flows from operating activities	19,410	48,543	46,627	67,115
Cash received from disposal of property, plant and equipment	64,672	0	64,672	0
Cash paid for the acquisition of intangible assets and property, plant and equipment	(33,940)	(18,160)	(59,870)	(36,458)
Cash flows from investing activities	30,732	(18,160)	4,802	(36,458)
Repayments of short term borrowings	(2,054)	(2,028)	(4,188)	(24,702)
Repayments of short term borrowings	2,387	4,651	7,460	10,786
Cash outflows related to current financial liabilities	(12,298)	(6,631)	(12,298)	(6,631)
Interest and similar expenses paid	(13,569)	(11,223)	(23,597)	(17,738)
Interest and similar income received	4,612	2,678	8,732	4,428
Dividends paid to shareholders	(11,944)	(11,169)	(23,808)	(21,955)
Cash flows from financing activities	(32,866)	(23,722)	(47,699)	(55,812)
Change in cash	17,276	6,661	3,730	(25,155)
Change in cash resulting from exchange rate differences	(3,537)	234	(2,561)	2,650
Cash and cash equivalents at the beginning of the period	59,714	48,506	72,284	77,906
Cash and cash equivalents at the end of the period	$ 73,453	$ 55,401	$ 73,453	$ 55,401

Interim Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Subscribed capital	Treasury shares	Capital reserves	Translation reserve	Cash flow hedge reserve	Reserve for hedges of a net investment in foreign operation	Reserve for actuarial gains (losses) on defined benefit plans	Retained Earnings
Number of common shares, Beginning of Period (in shares) at Dec. 31, 2016		59,320,214
Equity, Beginning of Period at Dec. 31, 2016	$ 55,743	$ 83,770	$ (3,773)	$ 139,399	$ 4,237	$ 793	$ (16,055)	$ (21,006)	$ (131,622)
Entity Information [Line Items]
Profit for the period	35,243								35,243
Other comprehensive income, net of tax	60				(7,338)	(792)	8,740	(550)
Total comprehensive income, net of tax all attributable to equity holders of the parent	35,303				(7,338)	(792)	8,740	(550)	35,243
Dividends paid	(21,955)			(21,955)
Share based payments	3,209			3,209
Number of common shares, End of Period (in shares) at Jun. 30, 2017		59,320,214
Equity, End of Period at Jun. 30, 2017	72,300	$ 83,770	(3,773)	120,653	(3,101)	1	(7,315)	(21,556)	(96,379)
Entity Information [Line Items]
Beginning of period, as adjusted	91,314	$ 83,770	(3,773)	102,529	(1,312)	(314)	(1,486)	(23,198)	(64,902)
Number of common shares, Beginning of Period (in shares) at Dec. 31, 2017		59,320,214
Equity, Beginning of Period at Dec. 31, 2017	99,856
Entity Information [Line Items]
Profit for the period	76,919								76,919
Other comprehensive income, net of tax	(14,833)				(13,421)	(1,557)	(8)	153
Total comprehensive income, net of tax all attributable to equity holders of the parent	62,086				(13,421)	(1,557)	(8)	153	76,919
Dividends paid	(23,808)			(23,808)
Share-based payments (in shares)		401,737
Share based payments	1,214	$ 484	16	714
Number of common shares, End of Period (in shares) at Jun. 30, 2018		59,721,951
Equity, End of Period at Jun. 30, 2018	$ 130,806	$ 84,254	$ (3,757)	$ 79,435	$ (14,733)	$ (1,871)	$ (1,494)	$ (23,045)	$ 12,017

Organization and principal activities	6 Months Ended
Organization and principal activities	Jun. 30, 2018
Corporate Information And Statement Of IFRS Compliance [Abstract]
Organization and principal activities	Organization and principal activities Orion Engineered Carbons S.A. (“Orion” or the "Company") is entered in the commercial register of Luxembourg under no. B 160558; the Company’s registered office is in Luxembourg; its business address is 6, Route de Trèves, L-2633 Senningerberg (Municipality of Niederanven), Grand Duchy of Luxembourg. Orion’s unaudited interim condensed consolidated financial statements comprise Orion and its subsidiaries (the “Orion Group” or the “Group”). Orion was incorporated on April 13, 2011. Orion’s fiscal year is the calendar year. Orion Group is a leading global manufacturer of carbon black products and is based in Luxembourg. Carbon black is a powdered form of carbon that is used to create the desired physical, electrical and optical qualities of various materials. Carbon black products are primarily used as consumables and additives for the production of polymers, printing inks and coatings (“Specialty Carbon Black” or “Specialties”) and in the reinforcement of rubber polymers (“Rubber Carbon Black” or “Rubber”). Specialty Carbon Black are high-tech materials which are mainly used for polymers, printing systems and coatings applications. The various production processes result in a wide range of different Specialty Carbon Black pigment grades with respect to their primary particle size, structure and surface area/surface chemistry. These parameters affect jetness, tinting strength, undertone, dispersibility, oil absorption, electrical conductivity and other characteristics. The types of Rubber Carbon Black used in the rubber industry are manufactured according to strict specifications and quality standards. Structure and specific surface area are the key factors in optimizing reinforcement properties in rubber polymers. As at June 30, 2018, the Orion Group operates 12 wholly owned production facilities in Europe, North and South America, Asia and South Africa and three sales companies. Another ten holding companies and two service companies, as well as two former operating entities in Portugal and France (currently in dissolution), are consolidated in the Orion Group. In June 2018 production ceased at the Bupyeong plant in South Korea and was consolidated into the second production plant in South Korea located in Yeosu. Additionally, the Group operates a joint venture with one production facility in Germany. Orion’s global presence enables it to supply Specialty Carbon Black customers as well as international customers in the tire and rubber industry with the full range of carbon black grades and particle sizes. Sales activities are supported by sales and representative offices all around the globe. Integrated sales activities with key account managers and customer services are carried out in the United States, Brazil, South Korea, Germany and China. The Group’s unaudited interim condensed consolidated financial statements were authorized for issue by management on August 2, 2018.

Basis of preparation of the interim condensed consolidated financial statements

6 Months Ended

Jun. 30, 2018

Corporate Information And Statement Of IFRS Compliance [Abstract]

Basis of preparation of the interim condensed consolidated financial statements

Basis of preparation

The unaudited interim condensed consolidated financial statements as at and for the six months ended June 30, 2018 have been prepared in accordance with IAS 34 Interim Financial Reporting as issued by the International Accounting Standards Board (“IASB”). Due to the change in the Group's presentation currency from euros to US dollars effective as of January 1, 2018 these unaudited interim condensed consolidated financial statements are prepared in US dollars, the new presentation currency of the Group.

A change in presentation currency is a change in accounting policy which is accounted for retrospectively. Therefore, comparative information for periods prior to January 1, 2018 included in these unaudited interim condensed consolidated financial statements have been restated into US dollars accordingly. Historical financial information included in the Group’s Annual Report on Form 20-F, filed with the SEC on February 23, 2018, for the year ended 31 December 2017 previously reported in euro was the basis for restatement of historical information into US dollars using the procedures outlined below:


–	assets and liabilities denominated in non-US dollar currencies were translated into US dollars at the closing rates of exchange on the relevant balance sheet dates;


–	non-US dollar income and expenditure were translated at the average rates of exchange prevailing for the relevant periods;

–

the cumulative equity and translation reserves were nil at April 13, 2011, the date of incorporation of Orion, and these reserves have been restated on the basis that the Group has reported in US dollars since that date. Share capital, share premium and the other reserves were translated at the historic rates prevailing at April 13, 2011, and subsequent rates prevailing on the date of each transaction;


–	all restated amounts were extracted from the Group’s underlying financial records at applicable historical exchange rates.

All International Financial Reporting Standards ("IFRSs"), interpretations (IFRICs, SICs) originated by the IFRS Interpretations Committee applicable for the period ended June 30, 2018 have been applied.

The unaudited interim condensed consolidated financial statements do not include all the information and disclosures required in the annual financial statements, and should be read in conjunction with the Group’s annual financial statements for the year ended December 31, 2017.

The unaudited interim condensed consolidated financial statements are prepared in US dollars, the presentation currency of the Orion Group. Except where stated otherwise, all figures are presented in thousands of US dollars (USD k) for the sake of clarity. Due to rounding, numbers presented throughout the tables and notes herein may not add up precisely to the totals presented and percentages may not precisely reflect the absolute figures.

First-time adoption of accounting standards

The accounting policies adopted in the preparation of the interim condensed consolidated financial statements are - with the exception of IFRS 9 and IFRS 15 - consistent with those followed in the preparation of the Group’s annual financial statements for the year ended December 31, 2017. The following amendments to IFRS were adopted on January 1, 2018:


•	IFRS 9 Financial instruments

IFRS 9 issued on July 24, 2014 replaces IAS 39 Financial Instruments: Recognition and Measurement. IFRS 9 determines requirements for recognition and measurement, impairment, derecognition and general hedge accounting. The latest issued version supersedes all previous versions. IFRS 9 became effective as of January 1, 2018.

The adoption of IFRS 9 had an effect on the measurement of certain of the Group’s financial instruments while it had no material impact on the hedge accounting models used by the Group.

The impact from the new impairment approach outlined in section 5.4 of IFRS 9 and the required initial recognition of a loss allowance at an amount equal to lifetime expected credit losses for trade receivables did not result in a transition adjustment on retained earnings as of January 1, 2018, as other previously recorded specific allowances are now covered under the new IFRS 9 allowance approach for expected credit losses.

In July 2017 the IASB clarified the accounting treatment for modification of financial liabilities under IFRS 9. A modification gain or loss is required to be calculated as the difference between the original contractual cash flows and the modified cash flows discounted at the original effective interest rate. Such modification gain or loss is recognized in the income statement in the period of modification, and the modified cash flows are then amortized using the new effective interest rate.

The Company has entered into various modifications of its term loan liabilities in the fiscal years 2016 and 2017 while it recorded gains or losses of such modifications over the remaining terms of the respective modifications as permitted under IAS 39. Such modification amounts would have been recorded as immediate gain or loss at each modification date if the Company would have applied IFRS 9 in the past already.

IFRS 9 is generally required to be applied retrospectively; however the recognition of a modification gain or loss for historic modifications made to financial liabilities outstanding on the adoption date is recorded as an accumulative catch up adjustment in retained earnings on the adoption date. The cumulative effect of the modification adjustments amounted to a loss of USD 8,542k net of taxes and is reflected in the retained earnings as of January 1, 2018.


•	IFRS 15 Revenue from contracts with customers

The IASB issued IFRS 15 on May 28, 2014. IFRS 15 intends to combine and harmonize the revenue recognition methods issued in several standards and interpretations. IFRS 15 also determines the time and extent of revenue recognition. IFRS 15 replaces IAS 18 Revenue, IAS 11 Construction Contracts, IFRIC 13 Customer Loyalty Programs, IFRIC 15 Agreements for Construction of Real Estate, IFRIC 18 Transfer of Assets from Customers and SIC 31 Revenue-Barter Transactions. The Company has completed a group wide review of all material contracts with customers. The changes had no impact on the Company's revenue recognition. Performance obligations are almost entirely the transfer of goods. In a limited number of cases the service to ship goods to the Company's customers may qualify as a separate performance obligation while the price of such ancillary services are deemed to be immaterial and the realization of such services usually occurs at same point of time as the transfer of the main performance obligation. As the changes have no impact on revenue recognition there was no cumulative catch up adjustment recorded in retained earnings under the modified retrospective approach of adoption that is now applied.

Accounting standards issued but not yet effective

The IASB has issued accounting standards which were not yet effective in the current fiscal year. Any new accounting standards which are relevant for the Group’s consolidated financial statements will be adopted when they become effective.

The following relevant pronouncements by the IASB and IFRSIC were not effective as at the reporting date on June 30, 2018 and were not applied by the Group:


•	IFRS 16 Leases

In January 2016, the IASB issued the new standard IFRS 16 “Leases”, which supersedes the existing lease accounting according to IAS 17. The existing concept of operating and finance leases will be replaced and most leases will be recognized in the statement of financial position. IFRS 16 will be effective as of January 1, 2019.

The Group has operating lease contracts as well as very limited finance leases and the new standard will have an impact on Group accounting policies, procedures as well as financial statements and our key performance indicators. The Group has started to analyze the impact of IFRS 16. Refer to note (9.5) Contingent liabilities and other financial obligations in the last annual financial statements for fiscal year 2017 for details of our current lease obligations on an undiscounted basis totaling to $33.3 million. While the Group has not finalized its assessment, according to the provisions of the Standard, the right–to-use leased assets that do not meet the exemption criteria will increase property, plant and equipment and will result in the recognition of a corresponding lease obligation based on the existing contracts at the transition date. The exemption criteria will be applicable in rare cases. In 2017 the Group recorded $9.7 million as operating lease expenses. The Group estimates that a comparable amount of expenses will in the future be recorded as amortization and to a certain amount as finance expenses.

Segment information

6 Months Ended

Jun. 30, 2018

Operating Segments [Abstract]

Segment information

Operating segments

The Group’s business is organized by product for corporate management purposes and has the following two operating segments: “Rubber” and “Specialties”.

The performance of the operating segments is assessed by reference to Adjusted EBITDA (as defined below) which is the segment's measure of profit or loss. Group financing (including finance costs and finance income), adjustment items and income taxes are managed on a Group basis and are not allocated to operating segments.

Segment reconciliation for the three months ended June 30, 2018 and 2017:



	In USD k						In USD k
	For the Three Months Ended Jun 30,						For the Three Months Ended Jun 30,
	2018						2017
	Rubber		Specialties		Total segments		Rubber		Specialties		Total segments
Revenue	248,915		142,671		391,586		207,298		122,315		329,613
Cost of sales	(194,191	)	(84,622	)	(278,813	)	(164,179	)	(72,555	)	(236,734	)
Gross profit	54,724		58,049		112,773		43,119		49,760		92,879
Adjusted EBITDA	35,923		45,225		81,148		25,953		38,385		64,338
Adjusted EBITDA Margin	14.4	%	31.7	%	20.7	%	12.5	%	31.3	%	19.5	%
Depreciation amortization and impairment of intangible assets and property, plant and equipment	(14,470	)	(9,769	)	(24,239	)	(14,769	)	(9,266	)	(24,035	)
Share of profit of joint venture	(144	)	—		(144	)	(133	)	—		(133	)
Adjustment items					25,692						(1,950	)
EBIT					82,457						38,220

Segment reconciliation for the six months ended June 30, 2018 and 2017:



	In USD k						In USD k
	For the Six Months Ended Jun 30,						For the Six Months Ended Jun 30,
	2018						2017
	Rubber		Specialties		Total segments		Rubber		Specialties		Total segments
Revenue	513,943		284,342		798,285		415,255		238,423		653,678
Cost of sales	(400,798	)	(172,311	)	(573,109	)	(322,827	)	(142,434	)	(465,261	)
Gross profit	113,145		112,031		225,176		92,428		95,989		188,417
Adjusted EBITDA	71,579		85,561		157,140		54,345		72,612		126,957
Adjusted EBITDA Margin	13.9	%	30.1	%	19.7	%	13.1	%	30.4	%	19.4	%
Depreciation amortization and impairment of intangible assets and property, plant and equipment	(29,374	)	(19,655	)	(49,029	)	(28,771	)	(17,506	)	(46,277	)
Share of profit of joint venture	(293	)	—		(293	)	(262	)	—		(262	)
Adjustment items					19,972						(5,179	)
EBIT					127,790						75,239

Definition of “Adjusted EBITDA”

“EBIT” (operating result) is defined as profit or loss for the period before income taxes and finance income and finance costs. “EBITDA” is defined as EBIT before depreciation, amortization and impairment losses. For management reporting purposes and as defined in the credit agreement governing our term loans “Adjusted EBITDA” is defined as EBITDA adjusted for acquisition related expenses, restructuring expenses, consulting fees related to Group strategy, share of profit or loss of joint venture and certain other adjustments. The Company believes that each of these items have less bearing on its performance of the underlying core business. “Adjusted EBITDA” is the management’s measure of the segment result.

Adjusted EBITDA is reconciled to profit or loss as follows:



Reconciliation of profit or loss	In USD k				In USD k
	For the Three Months Ended Jun 30,				For the Six Months Ended Jun 30,
	2018		2017		2018		2017
Profit for the period	52,691		18,428		76,919		35,243
Add back income taxes	20,558		9,023		33,722		18,986
Profit before income taxes	73,249		27,451		110,641		54,229
Add back finance costs	28,475		17,147		37,420		41,355
Add back share of profit of joint ventures	(144	)	(133	)	(293	)	(262	)
Add back other finance income	(19,123	)	(6,245	)	(19,978	)	(20,083	)
Earnings before taxes and finance income/costs (operating result (EBIT))	82,457		38,220		127,790		75,239
Add back depreciation, amortization and impairment of intangible assets and property, plant and equipment	24,239		24,035		49,029		46,277
EBITDA	106,696		62,255		176,819		121,516
Add back share of profit of joint venture	144		133		293		262
Add back restructuring (income)/expenses, net ⁽¹⁾	(29,751	)	319		(28,485	)	722
Add back consulting fees related to Group strategy ⁽²⁾	151		810		1,035		1,049
Add back long term incentive plan	2,853		1,609		5,953		3,209
Add back other adjustments ⁽³⁾	1,055		(788	)	1,525		199
Adjusted EBITDA	81,148		64,338		157,140		126,957

(1) Restructuring income or expenses are related to further actions undertaken to realign our worldwide Rubber footprint and reflects in particular the proceeds of the land sale in South Korea exceeding the associated cessation costs in three and six months ended June 30, 2018.

(2) Consulting fees related to external consulting fees from establishing and executing Group strategies.

(3) Other adjustments in the three and six months ended June 30, 2018 related in particular to license fees required for certain innovative technologies to meet the EPA requirements of USD 1.1 million. Other adjustments include income in the three months ended June 30, 2017 related to a reimbursement following a successful objection against reassessed real estate transfer taxes in Germany of USD 1.5 million, primarily offset by costs in association with our EPA enforcement action of USD 0.5 million. In addition to the real estate transfer tax reimbursement of USD 1.5 million other adjustments in the six months ended June 30, 2017 include costs of USD 1.4 million in connection with our EPA enforcement action.

Geographic information by legal entity



Revenues	In USD k		In USD k
	For the Three Months Ended Jun 30,		For the Six Months Ended Jun 30,
	2018	2017	2018	2017
Germany	157,579	135,702	324,974	261,875
United States	100,290	82,422	196,905	166,407
South Korea	72,437	57,487	146,058	118,202
Brazil	21,349	19,503	43,265	39,096
China	16,860	12,717	38,486	25,833
South Africa	14,244	12,002	28,625	23,932
Other	5,770	6,930	10,556	12,496
Rest of Europe*	3,057	2,850	9,416	5,837
Total	391,586	329,613	798,285	653,678


*	Country of domicile of the Group (Luxembourg) USD nil



Goodwill, intangible assets, property, plant and equipment	In USD k	In USD k
	As at Jun 30,	As at Dec 31,
	2018	2017
Germany	136,710	145,837
Sweden	72,095	80,974
Italy	65,124	72,980
Poland	43,466	49,933
Rest of Europe	3,561	4,443
Subtotal Europe	320,956	354,167

United States	85,243	70,530
South Korea	84,943	109,905
South Africa	29,081	32,007
Brazil	17,289	13,661
China	9,261	10,733
Other	35	28
Total	546,808	591,031

Other operating income, other operating expenses, restructuring income and expenses, financial result

6 Months Ended

Jun. 30, 2018

Analysis of income and expense [abstract]

Other operating income, other operating expenses, restructuring income and expenses, financial result

Other operating income decreased by USD 1,815k from USD 2,274k for the six months ended June 30, 2017 to USD 459k for the six months ended June 30, 2018. Other operating income for the six months ended June 30, 2017 mainly comprised of USD 1,432k reimbursement of property tax paid.

Other operating expenses decreased by USD 734k from USD 4,290k for the six months ended June 30, 2017 to USD 3,556k for the six months ended June 30, 2018. Other operating expenses for the six months ended June 30, 2018 mainly include consulting fees of USD 1,035k and other items that have less bearing on performance of the underlying core business of USD 1,525k compared to USD 1,049k and USD 199k, respectively, in the six months ended June 30, 2017 - for further details please see Note 3 (Segment information). Moreover, other operating expenses for the six months ended June 30, 2018 included allowances on trade receivables of USD 172k compared to USD 637k in six months ended June 30, 2017.

The restructuring of the South Korean footprint concluded in the second quarter of 2018 resulting in cessation of production at the Bupyeong plant and the sale of the land to a third party. Restructuring income is reflecting the proceeds of the land sale less the remaining book value of the land. Restructuring expenses comprise required costs for land restoration of USD 4,021k and cost to consolidate the two South Korean production sites into one remaining site in particular personnel related termination costs of USD 4,363k. This resulted in a net restructuring income of USD 29,751k in the three months ended June 30, 2018. For the six months ended June 30, 2018 net restructuring income amounted to USD 28,485k following restructuring expenses of USD 722k for the six months ended June 30, 2017 related in particular to costs to consolidate the production sites.

Financial result includes finance income, finance costs and share of profit or loss of joint ventures. Financial result decreased by USD 3,861k from USD 21,010k net finance expenses for the six months ended June 30, 2017 to USD 17,149k net finance expenses for the six months ended June 30, 2018. Total net foreign currency revaluation loss in finance result amounted USD 2,667k for the six months ended June 30, 2018 compared to a loss of USD 2,835k for the six months ended June 30, 2017. Interest related to the term loans amounted to USD 11,395k for the six months ended June 30, 2018 compared to USD 12,479k for the six months ended June 30, 2017.

The table below presents a breakdown of financial result for the six months ended June 30, 2018 and 2017:



Financial Result	In USD k
	For the Six Months Ended Jun 30,
	2018		2017
Interest expense on term loans	(11,395	)	(12,479	)
Amortization of transaction costs	(2,119	)	(2,437	)
Commitment bank charge	(865	)	(612	)
Interest income	2,776		807
Interest on non-current provisions	(1,051	)	(920	)
Other interest expense, net	(2,110	)	(2,796	)
Total net interest expenses	(14,764	)	(18,437	)
Gains from foreign currency revaluation	17,202		19,276
Losses from foreign currency revaluation	(19,869	)	(22,111	)
Net foreign currency revaluation impact	(2,667	)	(2,835	)
Bank guarantee expense	(11	)	—
Share of profit of joint ventures	293		262
Financial Result	(17,149	)	(21,010	)

Share-based payments

6 Months Ended

Jun. 30, 2018

Share-Based Payment Arrangements [Abstract]

Share-based payments

On July 31, 2015 the Company established the Long Term Incentive Plan ("LTIP" or the "2015 Plan") providing for the grant of performance share units (“PSUs”) to employees and officers selected by the Compensation Committee of the Board of Directors (the “Compensation Committee”). PSU awards are earned based on achievement against one or more performance metrics established by the Compensation Committee in respect of a specified performance period. Earned PSUs range from zero to a specified maximum percentage of a participant's target award based on the performance of applicable performance metrics, and are also subject to vesting terms based on continued employment. The first performance period was settled at the beginning of the second quarter of 2018, with PSUs earned based on achievement of EBITDA metrics established by the Compensation Committee and total shareholder return relative to a peer group. Earned and vested, PSUs settled in one share of Company common stock per vested PSU (or, at the Company’s election, cash equal to the fair market value thereof). The first vesting period ended March 31, 2018 (the “2015 Plan”) and PSUs common stocks are issued to participants on April 30, 2018 except for certain PSUs settled in cash at fair market value to cover wage taxes or as substitute for share transfer restrictions. All PSUs are granted under, and are subject to the terms and conditions of, the Company’s 2014 Incentive Compensation Plan, and do not increase the number of shares previously reserved for issuance under that plan. On August 2, 2016 the Compensation Committee established a consecutive LTIP (the "2016 Plan") having consistent terms as compared to the 2015 Plan. On July 31, 2017 the Compensation Committee established a consecutive LTIP (the "2017 Plan"). The following table details the costs charged to the income statement with respect to the 2015 Plan, 2016 Plan and 2017 Plan.



	USD k
	For the Six Months Ended Jun 30,
	2018	2017
Expense arising from equity-settled share based payment transactions (2015 Plan)	777	1,241
Expense arising from equity-settled share based payment transactions (2016 Plan)	2,253	1,968
Expense arising from equity-settled share based payment transactions (2017 Plan)	2,360	—
Expenses arising form equity-settled share based 2018 incentive	563	—
Total expenses	5,953	3,209

The following table illustrates the number of, and movements in, performance share units ("PSUs") during the period.



	2015 Plan				2016 Plan				2017 Plan			Total
	Number of PSUs				Number of PSUs				Number of PSUs			Number of PSUs
	2018		2017		2018		2017		2018		2017	2018		2017
Outstanding at January 1,	452,816		454,959		686,038		690,279		472,040			1,610,894		1,145,238
Granted during the period	—		—		113		—		830			943		—
Forfeited during the period	(5,694	)	(1,515	)	(8,544	)	(4,241	)	(5,521	)		(19,759	)	(5,756	)
Vested during the period	(447,122	)	—		—		—		—			(447,122	)	—
Outstanding at June 30,	—		453,444		677,607		686,038		467,349		—	1,144,956		1,139,482

The Company created and registered 400,453 new shares on April 30, 2018 of which 380,436 shares were used to settled the 2015 Plan. The remaining new shares plus 1,284 treasury shares were granted to our Board of Directors as a 2018 incentive. The fair value of the PSUs settled on April 30, 2018 amounted to USD 26.80 per PSU. The remaining portion of PSUs vested on March 31, 2018 was settled in cash at fair market value to cover employee wage tax obligations or in very limited cases as a substitute were share settlement was impeded. All obligations of the Company arising form the 2015 Plan were fulfilled through settlement during the reporting period and settlement is reflected in the consolidated statement of changes in equity of the Company.

The following table lists the inputs to the model used for the grant date fair values of the 2015 Plan, 2016 Plan and 2017 Plan.



	2015 Plan	2016 Plan	2017 Plan
Dividend Yield (%)	2.14%	2.23%	1.88%
Expected Volatility OEC (%)	25.16%	32.07%	33.77%
Expected Volatility Peer Group (%)	13.90%	18.12%	17.30%
Correlation	0.5234	0.4952	0.4574
Risk-free interest rate (%)	0.90%	0.76%	1.45%
Model used	Monte Carlo	Monte Carlo	Monte Carlo
Weighted average fair value of PSUs granted in USD	17.41	17.21	24.89

Inventories

6 Months Ended

Jun. 30, 2018

Inventories [Abstract]

Inventories

The impairment allowance as of June 30, 2018 and June 30, 2017, respectively, amounted to USD 2,073k and USD 4,980k and developed as follows:



	In USD k
	2018		2017
As at January 1,	1,717		4,436
Currency translation	(48	)	375
Addition	1,276		2,826
Utilization	(342	)	(1,920	)
Release	(530	)	(737	)
As at June 30,	2,073		4,980

Financial assets and liabilities

6 Months Ended

Jun. 30, 2018

Financial Instruments [Abstract]

Financial assets and liabilities

The table below presents fair values and the allocation of the fair value measurements to the hierarchy levels as at June 30, 2018 and December 31, 2017.



	In USD k as at
	Jun 30, 2018			Dec 31, 2017
	Level 1	Level 2	Level 3	Level 1	Level 2	Level 3
Financial assets measured at fair value
Receivables from derivatives	—	4,554	—	—	3,554	—
Financial liabilities measured at fair value
Liabilities from derivatives	—	4,473	—	—	5,193	—
Liabilities for which fair values are disclosed
Liabilities to banks	—	—	—	—	—	—
Term loan	—	669,119	—	—	684,234	—
Local bank loans	—	—	—	—	12,512	—

The receivables from derivatives of USD 4,554k and USD 3,554k as at June 30, 2018 and December 31, 2017, respectively, are presented in other non-current financial assets with an amount of USD 570k and USD 2,647k as at June 30, 2018 and December 31, 2017, respectively, and in other current financial assets with an amount of USD 3,984k and USD 907k as at June 30, 2018 and December 31, 2017, respectively. In 2014 and 2017 the Company acquired interest rate caps (both Euro and USD denominated) to hedge interest rate risks on current term loan financing. Since 2017 the Company has been entering into commodity derivative agreements to hedge the impact of raw material price fluctuations on cost of sales for specific sales.

The liabilities from derivatives of USD 4,473k and USD 5,193k as at June 30, 2018 and December 31, 2017, respectively, are presented in other financial liabilities. Those derivatives are solely used to hedge the on balance sheet payables and receivables and interest rate payments on the term loan as part of our hedging strategy.

On May 8, 2018 Orion signed an amendment to the credit agreement to reprice its EUR- and USD-denominated outstanding term loans. The repricing on the US dollar tranche reflects a 50 basis point reduction on margin from 2.50% to 2.00%, whereas on the euro tranche there is a 25 basis point reduction on margin from 2.50% to 2.25%. This repricing will reduce Orion's current annual interest payments by approximately USD 2.4 million. Other provisions to this credit agreement remained unchanged. In conjunction with the amendment of the credit agreement Orion effectively converted on May 11, 2018 USD 235,000k of its USD-denominated term loan into EUR by way of a cross currency swap as part of a new hedging approach. This swap transaction impacts both principal and interest payments associated with debt service and will result in a further annual interest payments savings of approximately USD 4.7 million over and above the interest savings achieved by the amendment itself. The swap became effective on May 15, 2018 and will expire on July 25, 2024, in line with maturity of the term loan. As result of the new cross currency swap, Orion terminated the current USD denominated interest rate caps on May 14, 2018, and received the proceeds of the termination of USD 4.0 million on May 16, 2018.

A portion of the USD-denominated term loan was designated as a hedge of the net investment in a foreign operation to reduce the Company's foreign currency exposure. Since January 1, 2015 the Company had designated USD 180 million of the total USD denominated term loan held by a Germany based subsidiary as the hedging instrument to hedge the change in net assets of a US subsidiary, which is held by a Germany based subsidiary, to manage foreign currency risk. Due to the new hedging approach and the new cross currency swap as described above, hedge accounting for the net investment hedge was discontinued on May 15, 2018. An unrealized loss of USD 2.2 million remains within other comprehensive income until it is recycled through profit and loss upon divestment of the hedged item.

In light of the above measures the refinancing activities qualified as an extinguishment and an amount of USD 1.7 million of capitalized transaction costs were released through finance expenses in the three months ended June 30, 2018 while new transaction costs of USD 0.7 million were capitalized and will be amortized over time in line with maturity of the term loan.

The USD-denominated term loan decreased during the first six months ended June 30, 2018 from USD 288,426k at December 31, 2017 to USD 286,669k due to a regular repayment of 0.5% of the initial principal amount. The USD-equivalent of the euro term loan decreased during the first six months of 2018 from USD 395,808k at December 31, 2017 to USD 382,450k due to a regular repayment of 0.5% of the initial principal amount, and foreign exchange revaluation effects.

On May 11, 2018 local Korean entity fully repaid the local term loan facility with KEB Hana Bank amounting to KRW 13.3 billion (equivalent to USD 12.3 million) from proceeds of Korean land sale.

Deferred and current taxes	6 Months Ended
Deferred and current taxes	Jun. 30, 2018
Income Taxes [Abstract]
Deferred and current taxes	Deferred and current taxes The development of deferred tax assets and liabilities relates to changes in temporary differences and tax loss carry forwards. Income tax receivables decreased from USD 16,377k at December 31, 2017 to USD 14,983k at June 30, 2018 due to tax refunds received from tax authorities. Income tax liabilities increased from USD 15,539k at December 31, 2017 to USD 35,741k at June 30, 2018 due to the expense calculated for the period. Income taxes in the six months ended June 30, 2018 amounted to USD 33,722k compared to USD 18,986k in the six months ended June 30, 2017, reflecting profit in these periods. The effective tax rate of 30.5% for the six months ended June 30, 2018 deviated from the expected group rate of 32.0% primarily due to changes in recognition of valuation allowances on tax losses and deductible temporary differences in Germany, Brazil, South Africa and Luxembourg, impacting the rate by 4.03%. Offsetting these unfavorable impacts by 0.4% were benefits from tax exempt income due to ACE deduction in Italy and other effects by 1.24%. The remaining difference primarily relates to foreign tax rate differentials decreasing the tax rate by 3.9%. The effective tax rate of 35.0% for the six months ended June 30, 2017 deviated from the expected group rate of 32.0% primarily due to non-creditable withholding taxes on tax exempt dividends received from the South Korean subsidiary. The tax effect for the six months ended June 30, 2016 was 3.3% and the impact of this first quarter event will have a reduced effect on the annual effective tax rate over the remainder of the year. Other non-deductible business expenses and non-deductible interest expenses due to local trade tax adjustments for the Group's German entities also impacted the rate by 5.9%. Offsetting these unfavorable impacts by 1.6% were benefits from tax exempt income due to domestic production activities in the United States and ACE deduction in Italy. Changes in recognition of losses and deductible temporary differences in Luxembourg, Germany, Brazil, South Africa, and Sweden resulted in a further 3.3% decrease. The remaining difference primarily relates to foreign tax rate differentials of favorable 1.9%.

Contingent liabilities and other financial obligations

6 Months Ended

Jun. 30, 2018

Disclosure of contingent liabilities [abstract]

Contingent liabilities and other financial obligations

To safeguard the supply of raw materials, contractual purchase commitments under long-term supply agreements for raw materials, especially oil and gas, are in place with the following maturities:



	In USD k
	As at Jun 30,	As at Dec 31,
Maturity	2018	2017
Less than one year	222,321	109,207
1 to 5 years	325,122	236,639
More than 5 years	—	—

Total	547,443	345,846

EPA Consent Decree

During 2008 and 2009, the U.S. Environmental Protection Agency (“EPA”) contacted all U.S. carbon black producers as part of an industry-wide EPA initiative, requesting extensive and comprehensive information under Section 114 of the U.S. Clean Air Act. EPA used that information to determine, for each facility, that either: (i) the facility has been in compliance with the Clean Air Act; (ii) violations have occurred and enforcement litigation may be undertaken; or (iii) violations have occurred and a settlement of an enforcement case is appropriate. In response to information requests received by the Company’s U.S. facilities, the Company furnished information to the EPA on each of its U.S. facilities. EPA subsequently sent notices under Section 113(a) of the Clean Air Act in 2010 alleging violations of Prevention of Significant Deterioration (“PSD”) and Title V permitting requirements under the Clean Air Act at the Company’s Belpre (Ohio) facility. In October 2012, the Company received a corresponding notice and finding of violation (an “NOV”) alleging the failure to obtain PSD and Title V permits reflecting Best Available Control Technology (“BACT”) at several units of the Company’s Ivanhoe (Louisiana) facility, and in January 2013 the Company also received an NOV issued by the EPA for its facility in Borger (Texas) alleging the failure to obtain PSD and Title V permits reflecting BACT during the years 1996 to 2008. A comparable NOV the Company’s U.S. facility in Orange (Texas) was issued by the EPA in February 2013; and EPA issued an additional NOV in March 2016 alleging more recent non-PSD air emissions violations primarily at the dryers and the incinerator of the Orange facility.

In 2013, Orion began discussions with the EPA and the U.S. Department of Justice (“DOJ”) about a potential settlement to resolve the NOVs received, which ultimately led to a consent decree executed between Orion Engineered Carbons LLC (“Orion”) and the United States (on behalf of EPA), as well as the Louisiana Department of Environmental Quality. The consent decree (the “EPA CD”) was lodged in the U.S. District Court for the Western District of Louisiana and became effective on June 7, 2018. The consent decree resolves and settles the EPA’s claims of noncompliance set forth in the NOVs and in a respective complaint filed in court against Orion by the United States immediately prior to the lodging of the consent decree.

All five U.S. carbon black producers have settled with the U.S. government. Orion was one of the two last carbon black companies to sign a consent decree.

Under Orion’s EPA CD, Orion will install certain pollution control technology in order to further reduce SO2, NOx and particulate matter (PM) emissions at its four U.S. manufacturing facilities in Ivanhoe (Louisiana), Belpre (Ohio), Borger (Texas), and Orange (Texas). Orion estimates that the capital expenditures for these installations, to be incurred over approximately six years, at US dollar amounts of 110 to140 million. We caution, however, that the actual capital expenditures we might need to incur in order to fulfill the requirements of the EPA CD remain uncertain. The EPA CD allows some flexibility for Orion to choose among different technology solutions for reducing emissions and the locations where these solutions are implemented. The solutions Orion ultimately chooses to implement may differ in scope and operation from those it currently anticipates (including those discussed in the next paragraph) and factors, such as timing, locations, target levels, changing cost estimates and local regulations, could cause capital expenditures to exceed current estimates by a significant amount or affect Orion’s ability to meet the agreed target emission levels as anticipated or at all. Orion also agreed to and paid a civil penalty of USD 800,000 and agreed to perform environmental mitigation projects totaling USD 550,000. The EPA CD also requires the continuous monitoring of emissions reductions that Orion will need to comply with over a number of years. Noncompliance with applicable emissions limits could lead to further penalty payments to EPA.

As part of Orion’s compliance plan under the EPA CD, in April 2018 Orion signed a contract with Haldor Topsoe group to install its SNOX^TM emissions control technology to remove SO₂, NOx and dust particles from tail gases at Orion’s Ivanhoe, Louisiana Carbon Black production plant. The SNOX^TM technology has not been used previously in the carbon black industry.

Orion’s Share Purchase Agreement with Evonik in connection with the Acquisition provides for a partial indemnity from Evonik against various exposures, including, but not limited to, capital investments, fines and costs arising in connection with Clean Air Act violations that occurred prior to July 29, 2011. Except for certain less relevant allegations contained in the second NOV received for the Company’s facility in Orange (Texas) in March 2016, all of the other allegations made by the EPA with regard to all four of the Company’s U.S. facilities - as discussed above - relate to alleged violations before July 29, 2011. The indemnity provides for a recovery from Evonik of a share of the costs (including fines), expenses (including reasonable attorney’s fees, but excluding costs for maintenance and control in the ordinary course of business and any internal cost of monitoring the remedy), liabilities, damages and losses suffered and is subject to various contractual provisions including provisions set forth in the Share Purchase Agreement with Evonik, such as a de minimis clause, a basket, overall caps (which apply to all covered exposures and all covered environmental exposures, in the aggregate), damage mitigation and cooperation requirements, as well as a statute of limitations provision. Due to the cost-sharing and cap provisions in Evonik’s indemnity, the Company expects that substantial costs it has already incurred and will incur in this EPA enforcement initiative and the EPA CD could exceed the scope of the indemnity, perhaps in the tens of millions of Euros. In addition, Evonik has signaled that it may likely defend itself against claims under the indemnity. While the Company intends to enforce its rights vigorously, there is no assurance that the Company will be able to recover costs or expenditures incurred under the indemnity as it expects or at all.

Related parties	6 Months Ended
Related parties	Jun. 30, 2018
Related Party [Abstract]
Related parties	Related parties In addition to the subsidiaries included in the consolidated financial statements, there is one joint venture of Orion that is accounted for using the equity method which classifies as a related party. Furthermore, related parties include key management personnel having authority and responsibility for planning, directing and monitoring the activities of the Group directly or indirectly and their close family members. We have not entered into material related party transactions other than in the normal course of business.

Basis of preparation of the interim condensed consolidated financial statements (Policies)

6 Months Ended

Jun. 30, 2018

Corporate Information And Statement Of IFRS Compliance [Abstract]

First-time adoption of accounting standards

Accounting standards issued but not yet effective

The IASB has issued accounting standards which were not yet effective in the current fiscal year. Any new accounting standards which are relevant for the Group’s consolidated financial statements will be adopted when they become effective.

The following relevant pronouncements by the IASB and IFRSIC were not effective as at the reporting date on June 30, 2018 and were not applied by the Group:


•	IFRS 16 Leases

In January 2016, the IASB issued the new standard IFRS 16 “Leases”, which supersedes the existing lease accounting according to IAS 17. The existing concept of operating and finance leases will be replaced and most leases will be recognized in the statement of financial position. IFRS 16 will be effective as of January 1, 2019.

The Group has operating lease contracts as well as very limited finance leases and the new standard will have an impact on Group accounting policies, procedures as well as financial statements and our key performance indicators. The Group has started to analyze the impact of IFRS 16. Refer to note (9.5) Contingent liabilities and other financial obligations in the last annual financial statements for fiscal year 2017 for details of our current lease obligations on an undiscounted basis totaling to $33.3 million. While the Group has not finalized its assessment, according to the provisions of the Standard, the right–to-use leased assets that do not meet the exemption criteria will increase property, plant and equipment and will result in the recognition of a corresponding lease obligation based on the existing contracts at the transition date. The exemption criteria will be applicable in rare cases. In 2017 the Group recorded $9.7 million as operating lease expenses. The Group estimates that a comparable amount of expenses will in the future be recorded as amortization and to a certain amount as finance expenses.

First-time adoption of accounting standards

The accounting policies adopted in the preparation of the interim condensed consolidated financial statements are - with the exception of IFRS 9 and IFRS 15 - consistent with those followed in the preparation of the Group’s annual financial statements for the year ended December 31, 2017. The following amendments to IFRS were adopted on January 1, 2018:


•	IFRS 9 Financial instruments

IFRS 9 issued on July 24, 2014 replaces IAS 39 Financial Instruments: Recognition and Measurement. IFRS 9 determines requirements for recognition and measurement, impairment, derecognition and general hedge accounting. The latest issued version supersedes all previous versions. IFRS 9 became effective as of January 1, 2018.

The adoption of IFRS 9 had an effect on the measurement of certain of the Group’s financial instruments while it had no material impact on the hedge accounting models used by the Group.

The impact from the new impairment approach outlined in section 5.4 of IFRS 9 and the required initial recognition of a loss allowance at an amount equal to lifetime expected credit losses for trade receivables did not result in a transition adjustment on retained earnings as of January 1, 2018, as other previously recorded specific allowances are now covered under the new IFRS 9 allowance approach for expected credit losses.

In July 2017 the IASB clarified the accounting treatment for modification of financial liabilities under IFRS 9. A modification gain or loss is required to be calculated as the difference between the original contractual cash flows and the modified cash flows discounted at the original effective interest rate. Such modification gain or loss is recognized in the income statement in the period of modification, and the modified cash flows are then amortized using the new effective interest rate.

The Company has entered into various modifications of its term loan liabilities in the fiscal years 2016 and 2017 while it recorded gains or losses of such modifications over the remaining terms of the respective modifications as permitted under IAS 39. Such modification amounts would have been recorded as immediate gain or loss at each modification date if the Company would have applied IFRS 9 in the past already.

IFRS 9 is generally required to be applied retrospectively; however the recognition of a modification gain or loss for historic modifications made to financial liabilities outstanding on the adoption date is recorded as an accumulative catch up adjustment in retained earnings on the adoption date. The cumulative effect of the modification adjustments amounted to a loss of USD 8,542k net of taxes and is reflected in the retained earnings as of January 1, 2018.


•	IFRS 15 Revenue from contracts with customers

The IASB issued IFRS 15 on May 28, 2014. IFRS 15 intends to combine and harmonize the revenue recognition methods issued in several standards and interpretations. IFRS 15 also determines the time and extent of revenue recognition. IFRS 15 replaces IAS 18 Revenue, IAS 11 Construction Contracts, IFRIC 13 Customer Loyalty Programs, IFRIC 15 Agreements for Construction of Real Estate, IFRIC 18 Transfer of Assets from Customers and SIC 31 Revenue-Barter Transactions. The Company has completed a group wide review of all material contracts with customers. The changes had no impact on the Company's revenue recognition. Performance obligations are almost entirely the transfer of goods. In a limited number of cases the service to ship goods to the Company's customers may qualify as a separate performance obligation while the price of such ancillary services are deemed to be immaterial and the realization of such services usually occurs at same point of time as the transfer of the main performance obligation. As the changes have no impact on revenue recognition there was no cumulative catch up adjustment recorded in retained earnings under the modified retrospective approach of adoption that is now applied.

Accounting standards issued but not yet effective

The IASB has issued accounting standards which were not yet effective in the current fiscal year. Any new accounting standards which are relevant for the Group’s consolidated financial statements will be adopted when they become effective.

The following relevant pronouncements by the IASB and IFRSIC were not effective as at the reporting date on June 30, 2018 and were not applied by the Group:


•	IFRS 16 Leases

In January 2016, the IASB issued the new standard IFRS 16 “Leases”, which supersedes the existing lease accounting according to IAS 17. The existing concept of operating and finance leases will be replaced and most leases will be recognized in the statement of financial position. IFRS 16 will be effective as of January 1, 2019.

The Group has operating lease contracts as well as very limited finance leases and the new standard will have an impact on Group accounting policies, procedures as well as financial statements and our key performance indicators. The Group has started to analyze the impact of IFRS 16. Refer to note (9.5) Contingent liabilities and other financial obligations in the last annual financial statements for fiscal year 2017 for details of our current lease obligations on an undiscounted basis totaling to $33.3 million. While the Group has not finalized its assessment, according to the provisions of the Standard, the right–to-use leased assets that do not meet the exemption criteria will increase property, plant and equipment and will result in the recognition of a corresponding lease obligation based on the existing contracts at the transition date. The exemption criteria will be applicable in rare cases. In 2017 the Group recorded $9.7 million as operating lease expenses. The Group estimates that a comparable amount of expenses will in the future be recorded as amortization and to a certain amount as finance expenses.

First-time adoption of accounting standards

The accounting policies adopted in the preparation of the interim condensed consolidated financial statements are - with the exception of IFRS 9 and IFRS 15 - consistent with those followed in the preparation of the Group’s annual financial statements for the year ended December 31, 2017. The following amendments to IFRS were adopted on January 1, 2018:


•	IFRS 9 Financial instruments

IFRS 9 issued on July 24, 2014 replaces IAS 39 Financial Instruments: Recognition and Measurement. IFRS 9 determines requirements for recognition and measurement, impairment, derecognition and general hedge accounting. The latest issued version supersedes all previous versions. IFRS 9 became effective as of January 1, 2018.

The adoption of IFRS 9 had an effect on the measurement of certain of the Group’s financial instruments while it had no material impact on the hedge accounting models used by the Group.

The impact from the new impairment approach outlined in section 5.4 of IFRS 9 and the required initial recognition of a loss allowance at an amount equal to lifetime expected credit losses for trade receivables did not result in a transition adjustment on retained earnings as of January 1, 2018, as other previously recorded specific allowances are now covered under the new IFRS 9 allowance approach for expected credit losses.

In July 2017 the IASB clarified the accounting treatment for modification of financial liabilities under IFRS 9. A modification gain or loss is required to be calculated as the difference between the original contractual cash flows and the modified cash flows discounted at the original effective interest rate. Such modification gain or loss is recognized in the income statement in the period of modification, and the modified cash flows are then amortized using the new effective interest rate.

The Company has entered into various modifications of its term loan liabilities in the fiscal years 2016 and 2017 while it recorded gains or losses of such modifications over the remaining terms of the respective modifications as permitted under IAS 39. Such modification amounts would have been recorded as immediate gain or loss at each modification date if the Company would have applied IFRS 9 in the past already.

IFRS 9 is generally required to be applied retrospectively; however the recognition of a modification gain or loss for historic modifications made to financial liabilities outstanding on the adoption date is recorded as an accumulative catch up adjustment in retained earnings on the adoption date. The cumulative effect of the modification adjustments amounted to a loss of USD 8,542k net of taxes and is reflected in the retained earnings as of January 1, 2018.


•	IFRS 15 Revenue from contracts with customers

The IASB issued IFRS 15 on May 28, 2014. IFRS 15 intends to combine and harmonize the revenue recognition methods issued in several standards and interpretations. IFRS 15 also determines the time and extent of revenue recognition. IFRS 15 replaces IAS 18 Revenue, IAS 11 Construction Contracts, IFRIC 13 Customer Loyalty Programs, IFRIC 15 Agreements for Construction of Real Estate, IFRIC 18 Transfer of Assets from Customers and SIC 31 Revenue-Barter Transactions. The Company has completed a group wide review of all material contracts with customers. The changes had no impact on the Company's revenue recognition. Performance obligations are almost entirely the transfer of goods. In a limited number of cases the service to ship goods to the Company's customers may qualify as a separate performance obligation while the price of such ancillary services are deemed to be immaterial and the realization of such services usually occurs at same point of time as the transfer of the main performance obligation. As the changes have no impact on revenue recognition there was no cumulative catch up adjustment recorded in retained earnings under the modified retrospective approach of adoption that is now applied.

Segment information (Tables)

6 Months Ended

Jun. 30, 2018

Operating Segments [Abstract]

Disclosure of segment reconciliation

Segment reconciliation for the three months ended June 30, 2018 and 2017:



	In USD k						In USD k
	For the Three Months Ended Jun 30,						For the Three Months Ended Jun 30,
	2018						2017
	Rubber		Specialties		Total segments		Rubber		Specialties		Total segments
Revenue	248,915		142,671		391,586		207,298		122,315		329,613
Cost of sales	(194,191	)	(84,622	)	(278,813	)	(164,179	)	(72,555	)	(236,734	)
Gross profit	54,724		58,049		112,773		43,119		49,760		92,879
Adjusted EBITDA	35,923		45,225		81,148		25,953		38,385		64,338
Adjusted EBITDA Margin	14.4	%	31.7	%	20.7	%	12.5	%	31.3	%	19.5	%
Depreciation amortization and impairment of intangible assets and property, plant and equipment	(14,470	)	(9,769	)	(24,239	)	(14,769	)	(9,266	)	(24,035	)
Share of profit of joint venture	(144	)	—		(144	)	(133	)	—		(133	)
Adjustment items					25,692						(1,950	)
EBIT					82,457						38,220

Segment reconciliation for the six months ended June 30, 2018 and 2017:



	In USD k						In USD k
	For the Six Months Ended Jun 30,						For the Six Months Ended Jun 30,
	2018						2017
	Rubber		Specialties		Total segments		Rubber		Specialties		Total segments
Revenue	513,943		284,342		798,285		415,255		238,423		653,678
Cost of sales	(400,798	)	(172,311	)	(573,109	)	(322,827	)	(142,434	)	(465,261	)
Gross profit	113,145		112,031		225,176		92,428		95,989		188,417
Adjusted EBITDA	71,579		85,561		157,140		54,345		72,612		126,957
Adjusted EBITDA Margin	13.9	%	30.1	%	19.7	%	13.1	%	30.4	%	19.4	%
Depreciation amortization and impairment of intangible assets and property, plant and equipment	(29,374	)	(19,655	)	(49,029	)	(28,771	)	(17,506	)	(46,277	)
Share of profit of joint venture	(293	)	—		(293	)	(262	)	—		(262	)
Adjustment items					19,972						(5,179	)
EBIT					127,790						75,239

Adjusted EBITDA is reconciled to profit or loss as follows:



Reconciliation of profit or loss	In USD k				In USD k
	For the Three Months Ended Jun 30,				For the Six Months Ended Jun 30,
	2018		2017		2018		2017
Profit for the period	52,691		18,428		76,919		35,243
Add back income taxes	20,558		9,023		33,722		18,986
Profit before income taxes	73,249		27,451		110,641		54,229
Add back finance costs	28,475		17,147		37,420		41,355
Add back share of profit of joint ventures	(144	)	(133	)	(293	)	(262	)
Add back other finance income	(19,123	)	(6,245	)	(19,978	)	(20,083	)
Earnings before taxes and finance income/costs (operating result (EBIT))	82,457		38,220		127,790		75,239
Add back depreciation, amortization and impairment of intangible assets and property, plant and equipment	24,239		24,035		49,029		46,277
EBITDA	106,696		62,255		176,819		121,516
Add back share of profit of joint venture	144		133		293		262
Add back restructuring (income)/expenses, net ⁽¹⁾	(29,751	)	319		(28,485	)	722
Add back consulting fees related to Group strategy ⁽²⁾	151		810		1,035		1,049
Add back long term incentive plan	2,853		1,609		5,953		3,209
Add back other adjustments ⁽³⁾	1,055		(788	)	1,525		199
Adjusted EBITDA	81,148		64,338		157,140		126,957

(1) Restructuring income or expenses are related to further actions undertaken to realign our worldwide Rubber footprint and reflects in particular the proceeds of the land sale in South Korea exceeding the associated cessation costs in three and six months ended June 30, 2018.

(2) Consulting fees related to external consulting fees from establishing and executing Group strategies.

(3) Other adjustments in the three and six months ended June 30, 2018 related in particular to license fees required for certain innovative technologies to meet the EPA requirements of USD 1.1 million. Other adjustments include income in the three months ended June 30, 2017 related to a reimbursement following a successful objection against reassessed real estate transfer taxes in Germany of USD 1.5 million, primarily offset by costs in association with our EPA enforcement action of USD 0.5 million. In addition to the real estate transfer tax reimbursement of USD 1.5 million other adjustments in the six months ended June 30, 2017 include costs of USD 1.4 million in connection with our EPA enforcement action.

Disclosure of geographic information

Geographic information by legal entity



Revenues	In USD k		In USD k
	For the Three Months Ended Jun 30,		For the Six Months Ended Jun 30,
	2018	2017	2018	2017
Germany	157,579	135,702	324,974	261,875
United States	100,290	82,422	196,905	166,407
South Korea	72,437	57,487	146,058	118,202
Brazil	21,349	19,503	43,265	39,096
China	16,860	12,717	38,486	25,833
South Africa	14,244	12,002	28,625	23,932
Other	5,770	6,930	10,556	12,496
Rest of Europe*	3,057	2,850	9,416	5,837
Total	391,586	329,613	798,285	653,678


*	Country of domicile of the Group (Luxembourg) USD nil



Goodwill, intangible assets, property, plant and equipment	In USD k	In USD k
	As at Jun 30,	As at Dec 31,
	2018	2017
Germany	136,710	145,837
Sweden	72,095	80,974
Italy	65,124	72,980
Poland	43,466	49,933
Rest of Europe	3,561	4,443
Subtotal Europe	320,956	354,167

United States	85,243	70,530
South Korea	84,943	109,905
South Africa	29,081	32,007
Brazil	17,289	13,661
China	9,261	10,733
Other	35	28
Total	546,808	591,031

Other operating income, other operating expenses, restructuring income and expenses, financial result (Tables)

6 Months Ended

Jun. 30, 2018

Analysis of income and expense [abstract]

Disclosure of finance income and costs

The table below presents a breakdown of financial result for the six months ended June 30, 2018 and 2017:



Financial Result	In USD k
	For the Six Months Ended Jun 30,
	2018		2017
Interest expense on term loans	(11,395	)	(12,479	)
Amortization of transaction costs	(2,119	)	(2,437	)
Commitment bank charge	(865	)	(612	)
Interest income	2,776		807
Interest on non-current provisions	(1,051	)	(920	)
Other interest expense, net	(2,110	)	(2,796	)
Total net interest expenses	(14,764	)	(18,437	)
Gains from foreign currency revaluation	17,202		19,276
Losses from foreign currency revaluation	(19,869	)	(22,111	)
Net foreign currency revaluation impact	(2,667	)	(2,835	)
Bank guarantee expense	(11	)	—
Share of profit of joint ventures	293		262
Financial Result	(17,149	)	(21,010	)

Share-based payments (Tables)

6 Months Ended

Jun. 30, 2018

Share-Based Payment Arrangements [Abstract]

Disclosure of detail as to expenses recorded within the profit and loss with respect to the LTIP

The following table details the costs charged to the income statement with respect to the 2015 Plan, 2016 Plan and 2017 Plan.



	USD k
	For the Six Months Ended Jun 30,
	2018	2017
Expense arising from equity-settled share based payment transactions (2015 Plan)	777	1,241
Expense arising from equity-settled share based payment transactions (2016 Plan)	2,253	1,968
Expense arising from equity-settled share based payment transactions (2017 Plan)	2,360	—
Expenses arising form equity-settled share based 2018 incentive	563	—
Total expenses	5,953	3,209

Disclosure of the number of and movements in PSUs

The following table illustrates the number of, and movements in, performance share units ("PSUs") during the period.



	2015 Plan				2016 Plan				2017 Plan			Total
	Number of PSUs				Number of PSUs				Number of PSUs			Number of PSUs
	2018		2017		2018		2017		2018		2017	2018		2017
Outstanding at January 1,	452,816		454,959		686,038		690,279		472,040			1,610,894		1,145,238
Granted during the period	—		—		113		—		830			943		—
Forfeited during the period	(5,694	)	(1,515	)	(8,544	)	(4,241	)	(5,521	)		(19,759	)	(5,756	)
Vested during the period	(447,122	)	—		—		—		—			(447,122	)	—
Outstanding at June 30,	—		453,444		677,607		686,038		467,349		—	1,144,956		1,139,482

Disclosure of indirect measurement of fair value of goods or services received, other equity instruments granted during period

The following table lists the inputs to the model used for the grant date fair values of the 2015 Plan, 2016 Plan and 2017 Plan.



	2015 Plan	2016 Plan	2017 Plan
Dividend Yield (%)	2.14%	2.23%	1.88%
Expected Volatility OEC (%)	25.16%	32.07%	33.77%
Expected Volatility Peer Group (%)	13.90%	18.12%	17.30%
Correlation	0.5234	0.4952	0.4574
Risk-free interest rate (%)	0.90%	0.76%	1.45%
Model used	Monte Carlo	Monte Carlo	Monte Carlo
Weighted average fair value of PSUs granted in USD	17.41	17.21	24.89

Inventories (Tables)

6 Months Ended

Jun. 30, 2018

Property, plant and equipment [abstract]

Disclosure of impairment allowance on inventories

The impairment allowance as of June 30, 2018 and June 30, 2017, respectively, amounted to USD 2,073k and USD 4,980k and developed as follows:



	In USD k
	2018		2017
As at January 1,	1,717		4,436
Currency translation	(48	)	375
Addition	1,276		2,826
Utilization	(342	)	(1,920	)
Release	(530	)	(737	)
As at June 30,	2,073		4,980

Financial assets and liabilities (Tables)

6 Months Ended

Jun. 30, 2018

Financial Instruments [Abstract]

Disclosure of fair value measurement of assets

The table below presents fair values and the allocation of the fair value measurements to the hierarchy levels as at June 30, 2018 and December 31, 2017.



	In USD k as at
	Jun 30, 2018			Dec 31, 2017
	Level 1	Level 2	Level 3	Level 1	Level 2	Level 3
Financial assets measured at fair value
Receivables from derivatives	—	4,554	—	—	3,554	—
Financial liabilities measured at fair value
Liabilities from derivatives	—	4,473	—	—	5,193	—
Liabilities for which fair values are disclosed
Liabilities to banks	—	—	—	—	—	—
Term loan	—	669,119	—	—	684,234	—
Local bank loans	—	—	—	—	12,512	—

Contingent liabilities and other financial obligations (Tables)

6 Months Ended

Jun. 30, 2018

Disclosure of contingent liabilities [abstract]

Disclosure of long-term supply commitments

To safeguard the supply of raw materials, contractual purchase commitments under long-term supply agreements for raw materials, especially oil and gas, are in place with the following maturities:



	In USD k
	As at Jun 30,	As at Dec 31,
Maturity	2018	2017
Less than one year	222,321	109,207
1 to 5 years	325,122	236,639
More than 5 years	—	—

Total	547,443	345,846

Organization and principal activities - Narrative (Details)	Jun. 30, 2018 service_company facility holding_company sales_company
Disclosure of detailed information about business combination [line items]
Number of wholly owned production facilities	12
Number of sales companies \| sales_company	3
Number of holding companies \| holding_company	10
Number of service companies \| service_company	2
Portugal and France
Disclosure of detailed information about business combination [line items]
Number of former operating entities in dissolution	2
Germany
Disclosure of detailed information about business combination [line items]
Number of production facilities operating as a joint venture	1

Basis of preparation of the interim condensed consolidated financial statements - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jan. 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure of initial application of standards or interpretations [line items]
Cumulative effect of modification loss		$ 52,691	$ 18,428	$ 76,919	$ 35,243
Retained Earnings
Disclosure of initial application of standards or interpretations [line items]
Cumulative effect of modification loss				$ 76,919	$ 35,243
Retained Earnings \| IFRS 9
Disclosure of initial application of standards or interpretations [line items]
Cumulative effect of modification loss	$ (8,542)

Segment information - Narrative (Details)	6 Months Ended
Segment information - Narrative (Details)	Jun. 30, 2018 segment
Operating Segments [Abstract]
Number of operating segments	2

Segment information - Operating results by segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure of operating segments [line items]
Revenue	$ 391,586	$ 329,613	$ 798,285	$ 653,678
Cost of sales	(278,813)	(236,734)	(573,109)	(465,261)
Gross profit	112,773	92,879	225,176	188,417
Adjusted EBITDA	$ 81,148	$ 64,338	$ 157,140	$ 126,957
Adjusted EBITDA Margin	20.70%	19.50%	19.70%	19.40%
Depreciation amortization and impairment of intangible assets and property, plant and equipment	$ (24,239)	$ (24,035)	$ (49,029)	$ (46,277)
Share of profit of joint venture	(144)	(133)	(293)	(262)
Adjustment items	25,692	(1,950)	19,972	(5,179)
Earnings before taxes and finance income/costs (operating result (EBIT))	82,457	38,220	127,790	75,239
Rubber
Disclosure of operating segments [line items]
Revenue	248,915	207,298	513,943	415,255
Cost of sales	(194,191)	(164,179)	(400,798)	(322,827)
Gross profit	54,724	43,119	113,145	92,428
Adjusted EBITDA	$ 35,923	$ 25,953	$ 71,579	$ 54,345
Adjusted EBITDA Margin	14.40%	12.50%	13.90%	13.10%
Depreciation amortization and impairment of intangible assets and property, plant and equipment	$ (14,470)	$ (14,769)	$ (29,374)	$ (28,771)
Share of profit of joint venture	(144)	(133)	(293)	(262)
Specialties
Disclosure of operating segments [line items]
Revenue	142,671	122,315	284,342	238,423
Cost of sales	(84,622)	(72,555)	(172,311)	(142,434)
Gross profit	58,049	49,760	112,031	95,989
Adjusted EBITDA	$ 45,225	$ 38,385	$ 85,561	$ 72,612
Adjusted EBITDA Margin	31.70%	31.30%	30.10%	30.40%
Depreciation amortization and impairment of intangible assets and property, plant and equipment	$ (9,769)	$ (9,266)	$ (19,655)	$ (17,506)
Share of profit of joint venture	$ 0	$ 0	$ 0	$ 0

Segment information - Reconciliation of adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring And Related Costs [Line Items]
Profit for the period	$ 52,691	$ 18,428	$ 76,919	$ 35,243
Add back income taxes	20,558	9,023	33,722	18,986
Profit before income taxes	73,249	27,451	110,641	54,229
Add back finance costs	28,475	17,147	37,420	41,355
Add back share of profit of joint ventures	(144)	(133)	(293)	(262)
Add back other finance income	(19,123)	(6,245)	(19,978)	(20,083)
Earnings before taxes and finance income/costs (operating result (EBIT))	82,457	38,220	127,790	75,239
Add back depreciation, amortization and impairment of intangible assets and property, plant and equipment	24,239	24,035	49,029	46,277
EBITDA	106,696	62,255	176,819	121,516
Add back restructuring (income)/expenses, net	(29,751)	319	(28,485)	722
Add back consulting fees related to Group strategy	151	810	1,035	1,049
Add back long term incentive plan	2,853	1,609	5,953	3,209
Add back other adjustments	1,055	(788)	1,525	199
Adjusted EBITDA	81,148	64,338	157,140	126,957
EPA enforcement action expense	$ 1,100	500	$ 1,100	1,400
Reimbursed reassessed real estate transfer tax		$ 1,500		$ 1,500

Segment information - Revenue geographical information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure of geographical areas [line items]
Revenues	$ 391,586	$ 329,613	$ 798,285	$ 653,678
Germany
Disclosure of geographical areas [line items]
Revenues	157,579	135,702	324,974	261,875
United States
Disclosure of geographical areas [line items]
Revenues	100,290	82,422	196,905	166,407
South Korea
Disclosure of geographical areas [line items]
Revenues	72,437	57,487	146,058	118,202
Brazil
Disclosure of geographical areas [line items]
Revenues	21,349	19,503	43,265	39,096
China
Disclosure of geographical areas [line items]
Revenues	16,860	12,717	38,486	25,833
South Africa
Disclosure of geographical areas [line items]
Revenues	14,244	12,002	28,625	23,932
Other
Disclosure of geographical areas [line items]
Revenues	5,770	6,930	10,556	12,496
Rest of Europe
Disclosure of geographical areas [line items]
Revenues	$ 3,057	$ 2,850	$ 9,416	$ 5,837

Segment information - Goodwill, intangible assets, property, plant and equipment geographical information (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	$ 546,808	$ 591,031
Subtotal Europe
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	320,956	354,167
Germany
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	136,710	145,837
Sweden
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	72,095	80,974
Italy
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	65,124	72,980
Poland
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	43,466	49,933
Rest of Europe
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	3,561	4,443
United States
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	85,243	70,530
South Korea
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	84,943	109,905
South Africa
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	29,081	32,007
Brazil
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	17,289	13,661
China
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	9,261	10,733
Other
Disclosure of geographical areas [line items]
Goodwill, intangible assets, property, plant and equipment	$ 35	$ 28

Other operating income, other operating expenses, restructuring income and expenses, financial result - Other operating income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Analysis of income and expense [abstract]
Increase (decrease) in other operating income				$ (1,815)
Other operating income	$ 296	$ 2,127	$ 459	$ 2,274
Reimbursement of property tax paid			$ 1,432

Other operating income, other operating expenses, restructuring income and expenses, financial result - Other operating expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Analysis of income and expense [abstract]
Increase (decrease) in other operating expense				$ (734)
Other operating expenses	$ 1,561	$ 1,097	$ 3,556	4,290
Consulting fees related to Group strategy	$ 151	$ 810	1,035	1,049
Miscellaneous expenses			1,525	199
Allowance on trade receivables recorded			$ 172	$ 637

Other operating income, other operating expenses, restructuring income and expenses, financial result - Restructuring expenses (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) site	Jun. 30, 2017 USD ($)
Analysis of income and expense [abstract]
Restructuring expense, land restoration			$ 4,021
Number of sites consolidated \| site			2
Restructuring expense, personnel related termination costs			$ 4,363
Net restructuring income	$ 29,751	$ (319)	$ 28,485	$ (722)

Other operating income, other operating expenses, restructuring income and expenses, financial result - Finance income and expenses (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Analysis of income and expense [abstract]
Decrease in finance income (cost)	$ 3,861
Finance income (cost)	(17,149)	$ (21,010)
Foreign exchange gain (loss)	(2,667)	(2,835)
Interest expense on borrowings	$ 11,395	$ 12,479

Other operating income, other operating expenses, restructuring income and expenses, financial result - Schedule of financial results (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Analysis of income and expense [abstract]
Interest expense on term loans			$ (11,395)	$ (12,479)
Amortization of transaction costs	$ (1,700)		(2,119)	(2,437)
Commitment bank charge			(865)	(612)
Interest income			2,776	807
Interest on non-current provisions			(1,051)	(920)
Other interest expense, net			(2,110)	(2,796)
Total net interest expenses			(14,764)	(18,437)
Gains from foreign currency revaluation			17,202	19,276
Losses from foreign currency revaluation			(19,869)	(22,111)
Net foreign currency revaluation impact			(2,667)	(2,835)
Bank guarantee expense			(11)	0
Share of profit or loss of joint ventures	$ 144	$ 133	293	262
Financial Result			$ (17,149)	$ (21,010)

Share-based payments - Share-based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based payment expense	$ 2,853	$ 1,609	$ 5,953	$ 3,209
2015 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based payment expense			777	1,241
2016 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based payment expense			2,253	1,968
2017 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based payment expense			2,360	0
2018 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Share-based payment expense			$ 563	$ 0

Share-based payments - Movement in PSUs (Details)		6 Months Ended
Share-based payments - Movement in PSUs (Details)	Apr. 30, 2018 USD ($) shares	Jun. 30, 2018 shares	Jun. 30, 2017 shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding at January 1, (in shares)		1,610,894	1,145,238
Granted during the period (in shares)		943	0
Forfeited during the period (in shares)		(19,759)	(5,756)
Vested during the period (in shares)		(447,122)	0
Outstanding at June 30, (in shares)		1,144,956	1,139,482
2015 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding at January 1, (in shares)		452,816	454,959
Granted during the period (in shares)		0	0
Forfeited during the period (in shares)		(5,694)	(1,515)
Vested during the period (in shares)	380,436	(447,122)	0
Outstanding at June 30, (in shares)		0	453,444
Number of shares issued through share-based payment transactions, new shares (in shares)	400,453
Number of shares issued through share-based payment transactions, treasury shares (in shares)	1,284
Weighted average fair value at measurement date, other equity instruments settled (in dollars per share) \| $	$ 26.80
2016 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding at January 1, (in shares)		686,038	690,279
Granted during the period (in shares)		113	0
Forfeited during the period (in shares)		(8,544)	(4,241)
Vested during the period (in shares)		0	0
Outstanding at June 30, (in shares)		677,607	686,038
2017 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Outstanding at January 1, (in shares)		472,040
Granted during the period (in shares)		830
Forfeited during the period (in shares)		(5,521)
Vested during the period (in shares)		0
Outstanding at June 30, (in shares)		467,349	0

Share-based payments - Share-based compensation fair value assumptions (Details)	6 Months Ended
	Jun. 30, 2018 USD ($)
2015 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Dividend Yield (%)	2.14%
Expected Volatility OEC (%)	25.16%
Expected Volatility Peer Group (%)	13.90%
Correlation	0.5234
Risk-free interest rate (%)	0.90%
Weighted average fair value of PSUs granted in USD	$ 17.410
2016 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Dividend Yield (%)	2.23%
Expected Volatility OEC (%)	32.07%
Expected Volatility Peer Group (%)	18.12%
Correlation	0.4952
Risk-free interest rate (%)	0.76%
Weighted average fair value of PSUs granted in USD	$ 17.210
2017 Plan
Disclosure of terms and conditions of share-based payment arrangement [line items]
Dividend Yield (%)	1.88%
Expected Volatility OEC (%)	33.77%
Expected Volatility Peer Group (%)	17.30%
Correlation	0.4574
Risk-free interest rate (%)	1.45%
Weighted average fair value of PSUs granted in USD	$ 24.890

Inventories - Impairment allowance roll forward (Details) - Inventory Valuation Reserve - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Movement In Valuation Allowances And Reserves1 [Roll Forward]
Beginning Balance	$ 1,717	$ 4,436
Currency translation	(48)	375
Addition	1,276	2,826
Utilization	(342)	(1,920)
Release	(530)	(737)
Ending Balance	$ 2,073	$ 4,980

Financial assets and liabilities - Fair values to the fair value hierarchy (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	$ 1,192,585	$ 1,168,805
Level 1 \| At fair value \| Derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Level 1 \| At fair value \| Derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	0	0
Level 1 \| For which fair values are disclosed \| Borrowings \| Liabilities To Banks
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Level 1 \| For which fair values are disclosed \| Borrowings \| Term loan
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Level 1 \| For which fair values are disclosed \| Borrowings \| Local bank loans
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Level 2 \| At fair value \| Derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	4,473	5,193
Level 2 \| At fair value \| Derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	4,554	3,554
Level 2 \| For which fair values are disclosed \| Borrowings \| Liabilities To Banks
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Level 2 \| For which fair values are disclosed \| Borrowings \| Term loan
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	669,119	684,234
Level 2 \| For which fair values are disclosed \| Borrowings \| Local bank loans
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	12,512
Level 3 \| At fair value \| Derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Level 3 \| At fair value \| Derivatives
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Assets	0	0
Level 3 \| For which fair values are disclosed \| Borrowings \| Liabilities To Banks
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Level 3 \| For which fair values are disclosed \| Borrowings \| Term loan
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	0	0
Level 3 \| For which fair values are disclosed \| Borrowings \| Local bank loans
Disclosure Of Fair Value Measurement Of Assets And Liabilities [Line Items]
Liabilities	$ 0	$ 0

Financial assets and liabilities - Narrative (Details) ₩ in Billions					3 Months Ended	6 Months Ended
	May 16, 2018 USD ($)	May 11, 2018 USD ($)	May 11, 2018 KRW (₩)	May 08, 2018 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	May 15, 2018 USD ($)	May 07, 2018	Dec. 31, 2017 USD ($)
Subclassifications of assets, liabilities and equities [abstract]
Derivative financial assets					$ 4,554,000	$ 4,554,000				$ 3,554,000
Non-current derivative financial assets					570,000	570,000				2,647,000
Current derivative financial assets					3,984,000	3,984,000				907,000
Derivative financial liabilities					4,473,000	4,473,000				5,193,000
Disclosure of detailed information about borrowings [line items]
Borrowings expected reduction to interest paid				$ 2,400,000
Cash receipts from termination of interest cap	$ 4,000,000
Amortisation of transaction costs					1,700,000	$ 2,119,000	$ 2,437,000
Transaction costs capitalised					$ 700,000
US Denominated Credit Facility Term Loan
Disclosure of detailed information about borrowings [line items]
Borrowings, adjustment to interest rate basis				2.00%					2.50%
Borrowings decrease in interest rate				0.50%
Annual principal amount paid, percentage					0.50%	0.50%
Borrowings					$ 286,669,000	$ 286,669,000				288,426,000
EUR Denominated Credit Facility Term Loan
Disclosure of detailed information about borrowings [line items]
Borrowings, adjustment to interest rate basis				2.25%					2.50%
Borrowings decrease in interest rate				0.25%
Annual principal amount paid, percentage					0.50%	0.50%
Borrowings					$ 382,450,000	$ 382,450,000				$ 395,808,000
KEB Hana Bank Term Loan Facility
Disclosure of detailed information about borrowings [line items]
Repayments of non-current borrowings		$ 12,300,000	₩ 13.3
Cross Currency Swap Effective May 15, 2018
Disclosure of detailed information about borrowings [line items]
Borrowings expected reduction to interest paid		4,700,000.0
Nominal amount of hedging instrument		$ 235,000,000
Cross Currency Swap Effective January 1, 2015
Disclosure of detailed information about borrowings [line items]
Nominal amount of hedging instrument					$ 180,000,000	$ 180,000,000
Reserve for hedges of a net investment in foreign operation \| Cross Currency Swap Effective January 1, 2015
Disclosure of detailed information about borrowings [line items]
Accumulated other comprehensive loss								$ 2,200,000

Deferred and current taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2017
Income Taxes [Abstract]
Income tax receivables	$ 14,983		$ 14,983			$ 16,377
Income tax liabilities	35,741		35,741			$ 15,539
Income taxes	$ 20,558	$ 9,023	$ 33,722	$ 18,986
Effective tax rate in %			30.50%	35.00%
Applicable tax rate			32.00%	32.00%
Tax rate effect of change in recognition of losses and deductible temporary differences			4.03%	3.30%
Tax rate effect of revenues exempt from taxation			0.40%	1.60%
Tax rate effect of tax exempt dividends from subsidiary					3.30%
Tax rate effect from change in tax rate				5.90%
Tax rate effect of other			1.24%
Tax rate effect of foreign tax rates			3.90%	1.90%

Contingent liabilities and other financial obligations, schedule of long-term supply agreement commitments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Raw material commitments under long-term supply agreements	$ 547,443	$ 345,846
Less than one year
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Raw material commitments under long-term supply agreements	222,321	109,207
1 to 5 years
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Raw material commitments under long-term supply agreements	325,122	236,639
More than 5 years
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Raw material commitments under long-term supply agreements	$ 0	$ 0

Contingent liabilities and other financial obligations, narrative (Details)	Dec. 22, 2017 USD ($) producer	Dec. 31, 2017 facility
Disclosure of contingent liabilities [line items]
Number of U. S. carbon black producers settled with U.S. government \| producer	5
Number of facilities located in the United States \| facility		4
Legal proceedings contingent liability
Disclosure of contingent liabilities [line items]
Estimated time period to install capital improvements in all U.S. facilities (up to)	6 years
Environmental loss contingency, civil penalty to the EPA	$ 800,000
Environmental loss contingency, mitigation projects	550,000
Legal proceedings contingent liability \| Bottom of range
Disclosure of contingent liabilities [line items]
Estimated capital cost to install controls in all U.S. facilities	110,000,000
Legal proceedings contingent liability \| Top of range
Disclosure of contingent liabilities [line items]
Estimated capital cost to install controls in all U.S. facilities	$ 140,000,000

Related parties - Narrative (Details)	Jun. 30, 2018 joint_venture
Related Party [Abstract]
Number of joint ventures accounted for using the equity method	1