Income Tax - Summary of Income Tax Reconciliation Using Composite Statutory Income Tax Rate Applicable by Tax Jurisdiction (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of average effective tax rate and applicable tax rate [abstract]
Income before income tax	€ 222	€ 49	€ 65
Composite statutory income tax rate applicable by tax jurisdiction	24.10%	31.90%	24.90%
Income tax (expense) / benefit calculated at composite statutory tax rate applicable by tax jurisdiction	€ (53)	€ (16)	€ (16)
Tax effect of:
Changes in recognized and unrecognized deferred tax assets	30	(61)	(45)
Change in tax rate		(11)	(6)
Other	(9)	8	(2)
Income tax (expense) / benefit	€ (32)	€ (80)	€ (69)
Effective income tax rate	14.00%	163.00%	106.00%

Adjustments for deferred tax expense to reconcile profit (loss) to net cash flow from (used in) operating activities. [Refer: Deferred tax expense (income); Profit (loss)]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 20
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_20&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_AdjustmentsForDeferredTaxExpense
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The applicable income tax rate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2018-01-01
-Paragraph 81
-Subparagraph c
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_81_c_ii&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_ApplicableTaxRate
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The tax expense (income) divided by the accounting profit. [Refer: Accounting profit]

+ References

+ Details

Name:	ifrs-full_AverageEffectiveTaxRate
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax. [Refer: Current tax expense (income); Deferred tax expense (income)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 26
-IssueDate 2018-01-01
-Paragraph 35
-Subparagraph b
-Clause viii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=26&date=2018-03-01&anchor=para_35_b_viii&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2018-01-01
-Paragraph 23
-Subparagraph h
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2018-03-01&anchor=para_23_h&doctype=Standard
-URIDate 2018-03-16

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2018-01-01
-Paragraph 79
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_79&doctype=Standard
-URIDate 2018-03-16

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2018-01-01
-Paragraph 81
-Subparagraph c
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_81_c_i&doctype=Standard
-URIDate 2018-03-16

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 82
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_82_d&doctype=Standard
-URIDate 2018-03-16

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2018-01-01
-Paragraph 81
-Subparagraph c
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_81_c_ii&doctype=Standard
-URIDate 2018-03-16

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2018-01-01
-Paragraph B13
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2018-03-01&anchor=para_B13_g&doctype=Appendix&seq=2
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_IncomeTaxExpenseContinuingOperations
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that the entity does not separately disclose in the same statement or note. [Refer: Accounting profit; Applicable tax rate]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2018-01-01
-Paragraph 81
-Subparagraph c
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_81_c_i&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_OtherTaxEffectsForReconciliationBetweenAccountingProfitAndTaxExpenseIncome
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The profit (loss) before tax expense or income. [Refer: Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 8
-IssueDate 2018-01-01
-Paragraph 28
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2018-03-01&anchor=para_28_b&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 8
-IssueDate 2018-01-01
-Paragraph 23
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=8&date=2018-03-01&anchor=para_23&doctype=Standard
-URIDate 2018-03-16

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 103
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_103&doctype=Standard
-URIDate 2018-03-16

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 102
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_102&doctype=Standard
-URIDate 2018-03-16

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 5
-IssueDate 2018-01-01
-Paragraph 33
-Subparagraph b
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=5&date=2018-03-01&anchor=para_33_b_i&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_ProfitLossBeforeTax
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to changes in the tax rate. [Refer: Accounting profit]

+ References

+ Details

Name:	ifrs-full_TaxEffectFromChangeInTaxRate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The product of the accounting profit multiplied by the applicable tax rate(s). [Refer: Accounting profit; Applicable tax rate]

+ References

+ Details

Name:	ifrs-full_TaxExpenseIncomeAtApplicableTaxRate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration