The amount of outstanding funds that the entity is obligated to repay.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_55&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_Borrowings
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The adjustment to the basis (reference rate) used for calculation of the interest rate on borrowings. [Refer: Borrowings]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 7
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_7&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_BorrowingsAdjustmentToInterestRateBasis
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of cash on hand and demand deposits, along with short-term, highly liquid investments that are readily convertible to known amounts of cash and that are subject to an insignificant risk of changes in value. [Refer: Cash; Cash equivalents]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2017-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_45&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2017-01-01
-Paragraph B13
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_B13_a&doctype=Appendix&seq=2
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 54
-Subparagraph i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_i&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_CashAndCashEquivalents
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfDetailedInformationAboutBorrowingsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of equity attributable to the owners of the parent. This specifically excludes non-controlling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 54
-Subparagraph r
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_r&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_EquityAttributableToOwnersOfParent
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Borrowings, Annual Minimum Principal Amount To Be Paid, Percentage

+ References

No definition available.

+ Details

Name:	oec_BorrowingsAnnualMinimumPrincipalAmountToBePaidPercentage
Namespace Prefix:	oec_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Borrowings, Variable Rate, Floor

+ References

No definition available.

+ Details

Name:	oec_BorrowingsVariableRateFloor
Namespace Prefix:	oec_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Invested Capital

+ References

No definition available.

+ Details

Name:	oec_InvestedCapital
Namespace Prefix:	oec_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	ifrs-full_BorrowingsByNameAxis=oec_CreditFacilityTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfInterestRatesAxis=ifrs-full_FixedInterestRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_TypesOfInterestRatesAxis=ifrs-full_FloatingInterestRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Other notes - Capital management, schedule of invested capital (Details) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 29, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 25, 2014
Disclosure of detailed information about borrowings [line items]
Reported equity	€ 83,262	€ 52,882			€ 49,686	€ 55,265
Term Loans (see note (7.10(a)))	558,569	618,059
Cash and cash equivalents	(60,272)	(73,907)			€ (65,261)	€ (70,544)
Total invested capital	€ 581,559	€ 597,034
Credit Facility Term Loan
Disclosure of detailed information about borrowings [line items]
EURIBOR and LIBOR floor	0.00%	0.75%	0.75%	1.00%			1.00%
Credit Facility Term Loan \| Fixed interest rate
Disclosure of detailed information about borrowings [line items]
Principal amount required to be repaid per annum (at least)	1.00%	1.00%					1.00%
Credit Facility Term Loan \| Floating interest rate
Disclosure of detailed information about borrowings [line items]
Borrowings, adjustment to interest rate basis	2.50%	3.00%