Goodwill - Goodwill (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line items]
Goodwill, beginning of period	€ 8,898
Changes in book value [Abstract]
Acquisitions	1,548	€ 140
Translation differences and other	(836)	248
Goodwill, end of period	7,731	8,898
Goodwill [Member]
Goodwill [Line items]
Goodwill, beginning of period	8,898	8,523
Changes in book value [Abstract]
Acquisitions	1,548	140
Divestments and transfers to assets classified as held for sale	(1,878)	(13)
Translation differences and other	(836)	248
Goodwill, end of period	7,731	8,898
Goodwill [Member] \| Cost
Goodwill [Line items]
Goodwill, beginning of period	11,151	10,704
Changes in book value [Abstract]
Goodwill, end of period	9,074	11,151
Goodwill [Member] \| Accumulated impairment [Member]
Goodwill [Line items]
Goodwill, beginning of period	(2,253)	(2,181)
Changes in book value [Abstract]
Goodwill, end of period	€ (1,343)	€ (2,253)

The increase in intangible assets and goodwill resulting from acquisitions through business combinations. [Refer: Business combinations [member]; Intangible assets and goodwill]

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The decrease in intangible assets and goodwill resulting from classification as held for sale or inclusion in a disposal group classified as held for sale. [Refer: Disposal groups classified as held for sale [member]; Intangible assets and goodwill]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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The amount of assets representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognised. [Refer: Business combinations [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The increase (decrease) in intangible assets and goodwill resulting from the net exchange differences arising when the financial statements are translated from the functional currency into a different presentation currency, including the translation of a foreign operation into the presentation currency of the reporting entity. [Refer: Intangible assets and goodwill]

+ References

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The amount of intangible assets and goodwill held by the entity. [Refer: Goodwill; Intangible assets other than goodwill]

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