Investment in associates and joint ventures - Summary of changes in investments in associates and joint ventures (Details) - EUR (€) € in Millions	6 Months Ended	12 Months Ended
Jun. 30, 2025	Dec. 31, 2024
Disclosure of investments in associates and joint ventures [line items]
Opening balance as at 1 January	€ 1,679
Closing balance	1,536	€ 1,679
Associates and joint ventures
Disclosure of investments in associates and joint ventures [line items]
Opening balance as at 1 January	1,679	1,509
Additions	1	26
Transfers	(10)	(7)
Revaluations	(11)	0
Share of results	85	205
Dividends received	(114)	(91)
Disposals	(2)	(16)
Impairments		(35)
Exchange rate differences	(91)	87
Closing balance	€ 1,536	€ 1,679

The increase (decrease) in financial assets resulting from foreign exchange. [Refer: Financial assets]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 7
-IssueDate 2024-01-01
-Paragraph IG20B
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2024-en-r&anchor=para_IG20B&doctype=Implementation%20Guidance
-URIDate 2024-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 7
-IssueDate 2024-01-01
-Paragraph 35H
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2024-en-r&anchor=para_35H&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_IncreaseDecreaseThroughForeignExchangeFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of investments in subsidiaries, joint ventures and associates in an entity's separate financial statements. [Refer: Total for all associates [member]; Total for all joint ventures [member]; Total for all subsidiaries [member]; Investments in subsidiaries reported in separate financial statements]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2024-01-01
-Paragraph 10
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2024-en-r&anchor=para_10&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_InvestmentsInSubsidiariesJointVenturesAndAssociates
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The entity's share of the profit (loss) of associates and joint ventures accounted for using the equity method. [Refer: Total for all associates [member]; Investments accounted for using equity method; Total for all joint ventures [member]; Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2024-01-01
-Paragraph 28
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2024-en-r&anchor=para_28_e&doctype=Standard
-URIDate 2024-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2024-01-01
-Paragraph 23
-Subparagraph g
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2024-en-r&anchor=para_23_g&doctype=Standard
-URIDate 2024-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 82
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_82_c&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_ShareOfProfitLossOfAssociatesAndJointVenturesAccountedForUsingEquityMethod
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Additions in investments in associates and joint ventures.

+ References

No definition available.

+ Details

Name:	ing_AdditionsInInvestmentsInAssociatesAndJointVentures
Namespace Prefix:	ing_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	ing_DecreaseInInvestmentsInSubsidiariesJointVenturesAndAssociatesFromDividendsReceived
Namespace Prefix:	ing_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Disclosure of investments in associates and joint ventures.

+ References

No definition available.

+ Details

Name:	ing_DisclosureOfInvestmentsInAssociatesAndJointVenturesLineItems
Namespace Prefix:	ing_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	ing_DisposalsOfInvestmentsInAssociatesAndJointVentures
Namespace Prefix:	ing_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

Name:	ing_ImpairmentLossOfInvestmentsInAssociatesAndJointVentures
Namespace Prefix:	ing_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Revaluation increase (decrease), Investments in associates and joint ventures.

+ References

No definition available.

+ Details

Name:	ing_RevaluationIncreaseDecreaseInvestmentsInAssociatesAndJointVentures
Namespace Prefix:	ing_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Transfer to and from Investments other assets and liabilities.

+ References

No definition available.

+ Details

Name:	ing_TransferToAndFromInvestmentsOtherAssetsAndLiabilities
Namespace Prefix:	ing_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=ing_AssociatesAndJointVenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: