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Related Parties - Narrative (Details) - EUR (€)					3 Months Ended	12 Months Ended
Related Parties - Narrative (Details) - EUR (€)	Feb. 06, 2025	Nov. 25, 2024	May 20, 2024	Jan. 05, 2021	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Disclosure of transactions between related parties [line items]
Unearned premiums						€ 4,743,348	€ 5,565,729
BBVA
Disclosure of transactions between related parties [line items]
Significant shareholder stake of the Company (as a percent)						0.77%	0.76%
Guarantees						€ 118,000,000	€ 239,000,000
Deposits maturity 2024							600,000,000
Purchase of goods						1,000,000	0
BBVA \| Derivative instruments
Disclosure of transactions between related parties [line items]
Credit derivative, fair value						106,000,000	52,000,000
Nominal amount of hedging instrument						€ 7,702,000,000	9,797,000,000
Credit derivatives, to total (in percentage)						9.00%
Guarantees						€ 24,000,000	45,000,000
Caixabank
Disclosure of transactions between related parties [line items]
Expense recognised during period for bad and doubtful debts for related party transaction					€ 3,000,000		6,000,000
Purchase of assets					29,000,000		117,000,000
Telefónica Factoring España, S.A. Factoring
Disclosure of transactions between related parties [line items]
Proportion of voting rights held in subsidiary (as a percent)						50.00%
Adquira España, S.A.
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint venture						44.44%
New fusion portfolio \| Caixabank
Disclosure of transactions between related parties [line items]
Purchase of goods					139,000,000		393,000,000
Expense recognised during period for bad and doubtful debts for related party transaction					€ 14,000,000		€ 33,000,000
BBVA
Disclosure of transactions between related parties [line items]
Significant shareholder stake of the Company (as a percent)						4.93%
Proportion of ownership shares held						0.231%
BBVA \| Adquira España, S.A.
Disclosure of transactions between related parties [line items]
Proportion of ownership interest in joint venture						44.44%
Sociedad Estatal de Participaciones Industriales "SEPI"
Disclosure of transactions between related parties [line items]
Significant shareholder stake of the Company (as a percent)			10.00%
Criteria Caixa S.A.U.
Disclosure of transactions between related parties [line items]
Significant shareholder stake of the Company (as a percent)						9.99%
Fundación Bancaria Caixa d'Estalvis i Pensions de Barcelona
Disclosure of transactions between related parties [line items]
Significant shareholder stake of the Company (as a percent)						9.99%
Telefonica Digital Espana \| Movistar Consumer Finance Colombia SAS.
Disclosure of transactions between related parties [line items]
Proportion of voting rights held in joint venture				50.00%
BlackRock Inc \| Telefónica, S.A.
Disclosure of transactions between related parties [line items]
Significant shareholder stake of the Company (as a percent)		4.29%
Green Bridge Investment Company \| Telefónica, S.A. \| Forecast
Disclosure of transactions between related parties [line items]
Significant shareholder stake of the Company (as a percent)	9.97%