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Pensions and Other Post-employment Benefit Obligations - Summary of Amounts Recognized in the Consolidated Statement of Financial Position (Detail) - EUR (€) € in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Disclosure of variation in financial position [line items] |  |
Present value of funded obligation | € 691 | € 721
Fair value of plan assets | (387) | (391)
Deficit of funded plans | 304 | 330
Present value of unfunded obligation | 360 | 405
Net liability arising from defined benefit obligation | 664 | 735
Pension benefits [member] |  |
Disclosure of variation in financial position [line items] |  |
Present value of funded obligation | 691 | 721
Fair value of plan assets | (387) | (391)
Deficit of funded plans | 304 | 330
Present value of unfunded obligation | 110 | 132
Net liability arising from defined benefit obligation | 414 | 462
Other benefits [member] |  |
Disclosure of variation in financial position [line items] |  |
Present value of unfunded obligation | 250 | 273
Net liability arising from defined benefit obligation | € 250 | € 273

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- Definition Disclosure of variation in financial position [line items] + References No definition available. + Details
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- Definition The present value, without deducting any plan assets, of expected future payments required to settle the obligation resulting from employee service in the current and prior periods. [Refer: Plan assets, at fair value] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_57_a&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of non-current net defined benefit liability. [Refer: Net defined benefit liability] + References 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
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- Definition The fair value of defined benefit plan assets. Plan assets comprise assets held by a long-term employee benefit fund and qualifying insurance policies. [Refer: At fair value [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_57_a&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The present value of the defined benefit obligation, less the fair value of the plan assets (if any). [Refer: Plan assets [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_57_a&doctype=Standard -URIDate 2017-03-09 + Details
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