Equity - OCI items may be reclassified: debt instruments (Details) - EUR (€) € in Millions	Jun. 30, 2020	Dec. 31, 2019
Financial assets at fair value through other comprehensive income [abstract]
Net revaluation gains/(losses)	€ 2,465	€ 2,321
Financial assets at fair value through comprehensive income	122,560	125,708
Debt Securities Plus Loans And Advances [Member]
Financial assets at fair value through other comprehensive income [abstract]
Revaluation gains	2,703	2,531
Revaluation losses	(238)	(210)
Net revaluation gains/(losses)	2,465	2,321
Financial assets at fair value through comprehensive income	120,332	122,845
Government debt securities and debt instruments issued by central banks \| Spain
Financial assets at fair value through other comprehensive income [abstract]
Revaluation gains	862	947
Revaluation losses	0	(2)
Net revaluation gains/(losses)	862	945
Financial assets at fair value through comprehensive income	23,167	32,413
Government debt securities and debt instruments issued by central banks \| Rest of Europe
Financial assets at fair value through other comprehensive income [abstract]
Revaluation gains	792	664
Revaluation losses	(69)	(38)
Net revaluation gains/(losses)	723	626
Financial assets at fair value through comprehensive income	17,993	19,052
Government debt securities and debt instruments issued by central banks \| Latin America and rest of the world
Financial assets at fair value through other comprehensive income [abstract]
Revaluation gains	893	839
Revaluation losses	(119)	(121)
Net revaluation gains/(losses)	774	718
Financial assets at fair value through comprehensive income	51,697	51,284
Private-sector debt securities
Financial assets at fair value through other comprehensive income [abstract]
Revaluation gains	156	81
Revaluation losses	(50)	(49)
Net revaluation gains/(losses)	106	32
Financial assets at fair value through comprehensive income	€ 27,475	€ 20,096

No definition available.

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- Definition

The amount of financial assets that are measured at fair value through other comprehensive income. A financial asset shall be measured at fair value through other comprehensive income if both of the following conditions are met: (a) the financial asset is held within a business model whose objective is achieved by both collecting contractual cash flows and selling financial assets and (b) the contractual terms of the financial asset give rise on specified dates to cash flows that are solely payments of principal and interest on the principal amount outstanding. [Refer: At fair value [member]; Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2019-01-01
-Paragraph 8
-Subparagraph h
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-URIDate 2019-03-27

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- Definition

A component of equity representing the reserve of gains and losses on financial assets measured at fair value through other comprehensive income. [Refer: Financial assets measured at fair value through other comprehensive income; Other comprehensive income]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 78
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_78_e&doctype=Standard
-URIDate 2019-03-27

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- Definition

The portion of the reserve of gains and losses on financial assets measured at fair value through other comprehensive income that represents accumulated gains.

+ References

No definition available.

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- Definition

The portion of the reserve of gains and losses on financial assets measured at fair value through other comprehensive income that represents accumulated revaluation losses.

+ References

No definition available.

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