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

The increase (decrease) in the entity's equity resulting from the change in the equity of subsidiaries. [Refer: Subsidiaries [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 106
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_106_d&doctype=Standard
-URIDate 2019-03-27

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

The proportion of ownership interest in a subsidiary attributable to the entity. [Refer: Subsidiaries [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2019-01-01
-Paragraph 17
-Subparagraph b
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2019-en-r&anchor=para_17_b_iii&doctype=Standard
-URIDate 2019-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2019-01-01
-Paragraph 16
-Subparagraph b
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2019-en-r&anchor=para_16_b_iii&doctype=Standard
-URIDate 2019-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2019-01-01
-Paragraph 19B
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2019-en-r&anchor=para_19B_c&doctype=Standard
-URIDate 2019-03-27

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

Impact of Transaction in Equity Attributable to Equity Holders

No definition available.

Name:	tef_ImpactofTransactioninEquityAttributabletoEquityHolders
Namespace Prefix:	tef_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Indirect participation percentage

No definition available.

Name:	tef_Indirectparticipationpercentage
Namespace Prefix:	tef_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage Of Voting Equity Transfered As Consideration

No definition available.

Name:	tef_PercentageOfVotingEquityTransferedAsConsideration
Namespace Prefix:	tef_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Proceeds From Exchange Of Share Capital

No definition available.

Name:	tef_ProceedsFromExchangeOfShareCapital
Namespace Prefix:	tef_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Transfer price per share

No definition available.

Name:	tef_Transferpricepershare
Namespace Prefix:	tef_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=tef_TelxiusTelecomMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_CounterpartiesAxis=tef_PontegadeaGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=tef_TelefonicaS.A.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=tef_PontelParticipacionesSLMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: