Deposits from central banks and credit institutions - Schedule of deposits from central banks and credit institutions (Details) - EUR (€) € in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deposits [Line Items]
Financial liabilities held for trading	€ 122,270	€ 115,185	€ 79,469
Financial liabilities designated at fair value through profit or loss	40,367	40,268	14,943
Financial liabilities at amortized cost	1,468,703	1,423,858	1,349,169
Euro
Deposits [Line Items]
Total financial liabilities	53,921	65,133	107,908
Pound sterling
Deposits [Line Items]
Total financial liabilities	27,697	35,357	42,451
US dollar
Deposits [Line Items]
Total financial liabilities	49,447	30,924	24,012
Brazilian real
Deposits [Line Items]
Total financial liabilities	7,997	14,195	11,297
Other currencies
Deposits [Line Items]
Total financial liabilities	19,580	19,176	15,521
Central banks and Credit institutions
Deposits [Line Items]
Total financial liabilities	158,642	164,785	201,189
Central banks
Deposits [Line Items]
Financial liabilities held for trading	7,808	5,757	1,038
Financial liabilities designated at fair value through profit or loss	1,209	1,740	607
Financial liabilities at amortized cost	48,782	76,952	139,757
Total financial liabilities	57,799	84,449	141,402
Central banks \| Deposits on demand
Deposits [Line Items]
Total financial liabilities	117	0	10
Central banks \| Time deposits
Deposits [Line Items]
Total financial liabilities	43,853	72,320	134,439
Central banks \| Reverse repurchase agreements
Deposits [Line Items]
Total financial liabilities	13,829	12,129	6,953
Credit institutions
Deposits [Line Items]
Financial liabilities held for trading	17,862	9,796	6,488
Financial liabilities designated at fair value through profit or loss	1,735	1,958	1,064
Financial liabilities at amortized cost	81,246	68,582	52,235
Total financial liabilities	100,843	80,336	59,787
Credit institutions \| Deposits on demand
Deposits [Line Items]
Total financial liabilities	5,468	6,808	6,139
Credit institutions \| Time deposits
Deposits [Line Items]
Total financial liabilities	54,402	49,221	37,332
Credit institutions \| Reverse repurchase agreements
Deposits [Line Items]
Total financial liabilities	40,689	24,245	16,198
Credit institutions \| Subordinated liabilities
Deposits [Line Items]
Total financial liabilities	€ 284	€ 62	€ 118

The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) 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 deliver 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, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are 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. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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-IssueDate 2023-01-01
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The amount of financial liabilities at amortised cost. The amortised cost is the amount at which financial liabilities are measured at initial recognition minus principal repayments, plus or minus the cumulative amortisation using the effective interest method of any difference between that initial amount and the maturity amount. [Refer: Financial liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2023-01-01
-Paragraph 8
-Subparagraph g
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2023-en-r&anchor=para_8_g&doctype=Standard
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The amount of financial liabilities at fair value through profit or loss that meet the definition of held for trading. A financial liability is classified as held for trading if: (a) it is acquired or incurred principally for the purpose of selling or repurchasing it in the near term; (b) on initial recognition it is part of a portfolio of identified financial instruments that are managed together and for which there is evidence of a recent actual pattern of short-term profit-taking; or (c) it is a derivative (except for a derivative that is a financial guarantee contract or a designated and effective hedging instrument). [Refer: Financial liabilities at fair value through profit or loss]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
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The amount of financial liabilities at fair value through profit or loss that were designated as such upon initial recognition or subsequently. [Refer: At fair value [member]; Financial liabilities at fair value through profit or loss]

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