Other disclosures - Disclosure of home purchase loans in Spain (Details) - Home purchase loans - Spain - EUR (€) € in Millions	6 Months Ended
Jun. 30, 2025	Dec. 31, 2024
Disclosure of credit risk exposure [line items]
Percentage secured by mortgage	99.66%
Gross carrying amount
Disclosure of credit risk exposure [line items]
Financial assets	€ 59,927	€ 59,316
Gross carrying amount \| Without collateral
Disclosure of credit risk exposure [line items]
Financial assets	201	208
Gross carrying amount \| With collateral
Disclosure of credit risk exposure [line items]
Financial assets	59,726	59,108
Credit impaired \| Gross carrying amount
Disclosure of credit risk exposure [line items]
Financial assets	729	789
Credit impaired \| Gross carrying amount \| Without collateral
Disclosure of credit risk exposure [line items]
Financial assets	6	11
Credit impaired \| Gross carrying amount \| With collateral
Disclosure of credit risk exposure [line items]
Financial assets	€ 723	€ 778

- Definition

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Classes of financial instruments [domain]; Financial liabilities]

+ References + Details