Provisions - Main Actuarial Assumptions Used in Valuing Defined Benefit Plans (Details) - Telefónica Spain - Foreign defined benefit plans	12 Months Ended
Dec. 31, 2018
Survival
Disclosure of defined benefit plans [line items]
Average duration of plans	7 years 5 months 1 day
Discount rate (as a percent)	1.32%
Survival \| Minimum
Disclosure of defined benefit plans [line items]
Expected rate of salary increase (as a percent)	0.00%
Survival \| Maximum
Disclosure of defined benefit plans [line items]
Expected rate of salary increase (as a percent)	0.50%
ITP
Disclosure of defined benefit plans [line items]
Average duration of plans	7 years 5 months 1 day
Discount rate (as a percent)	1.29%

The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2019-01-01
-Paragraph 144
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-URIDate 2019-03-27

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- Definition

The expected rate of salary increases used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]]

+ References

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- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

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- Definition

The weighted average duration of a defined benefit obligation. [Refer: Weighted average [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2019-01-01
-Paragraph 147
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2019-en-r&anchor=para_147_c&doctype=Standard
-URIDate 2019-03-27

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