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IFRSs not yet adopted (Details Textual) € in Millions	12 Months Ended
	Dec. 31, 2017 EUR (€)
DisclosureOfIfrssNotYetAdoptedLineItems [Line Items]
Customer acquisition costs capitalized	€ 60
Expected credit loss model [Member]
DisclosureOfIfrssNotYetAdoptedLineItems [Line Items]
ImpairmentLoss	€ 356
Intragroup related balances [Member]
DisclosureOfIfrssNotYetAdoptedLineItems [Line Items]
Description Of How Future Recovery Or Reversal Of Regulatory Deferral Account Balances is Affected By Risks And Uncertainty	For exposures arising from intragroup transactions, the recovery rate is assumed to be 100% in consideration of the possibility of providing for capital contribution to the investees in order to guarantee their solvency.
Increase Decrease Due To Application Of IFRS15 [Member]
DisclosureOfIfrssNotYetAdoptedLineItems [Line Items]
Decrease in equity	€ 43
Increase Decrease Due To Application Of IFRS15 [Member] | Sales method [Member]
DisclosureOfIfrssNotYetAdoptedLineItems [Line Items]
Decrease in equity	103
Increase decrease due to application of ifrs 9 [Member]
DisclosureOfIfrssNotYetAdoptedLineItems [Line Items]
Increase in equity	322
IncreaseDecreaseInFairValueMeasurementEntitysOwnEquityInstruments	€ 678

X

- Definition

The amount of customer acquisition costs capitalized during the year.

+ References

No definition available.

+ Details

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X

- Definition

The amount of decrease in equity due to effect of adoption of ifrs.

+ References

No definition available.

+ Details

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- References

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- Definition

The amount of increase in equity due to effect of adoption of ifrs.

+ References

No definition available.

+ Details

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X

- Definition

The description of how the future recovery or reversal of regulatory deferral account balances is affected by risks and uncertainty. [Refer: Regulatory deferral account balances [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 14
-IssueDate 2017-01-01
-Paragraph 30
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=14&date=2017-03-01&anchor=para_30_c&doctype=Standard
-URIDate 2017-03-09

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- Definition

The amount recognised as a reduction of the carrying amount of an asset or cash-generating unit to its recoverable amount. [Refer: Carrying amount [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 130
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_130_b&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2017-01-01
-Paragraph 130
-Subparagraph d
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=36&date=2017-03-01&anchor=para_130_d_ii&doctype=Standard
-URIDate 2017-03-09

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- Definition

The increase (decrease) in the fair value measurement of the entity's own equity instruments. [Refer: At fair value [member]; Entity's own equity instruments [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 13
-IssueDate 2017-01-01
-Paragraph 93
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=13&date=2017-03-01&anchor=para_93_e&doctype=Standard
-URIDate 2017-03-09

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