Principal subsidiaries, investments in associates and joint ventures - Summary of principal subsidiaries, investments in associates and joint ventures (Details)	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
TMBThanachart Bank Public Company Limited
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Interest held	23.00%	23.00%
ING Bank N.V.
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
Bank Mendes Gans N.V.
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
ING Belgium S.A./N.V.
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
ING Luxembourg S.A.
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
ING-DiBa AG
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
ING Bank Slaski S.A.
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	75.00%	75.00%
Proportion of ownership interests held by non-controlling interests		25.00%
ING Financial Holdings Corporation
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
ING Bank A.S.
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
ING Bank (Australia) Ltd
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
ING Commercial Finance B.V.
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%
ING Groenbank N.V.
Disclosure of Significant Investments in Principal Subsidiaries, Associates and Joint Ventures [Line Items]
Proportion of ownership and interest held by the group	100.00%	100.00%

The proportion of ownership interest in an associate attributable to the entity. [Refer: Associates [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 17
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_17_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 16
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_16_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph 21
-Subparagraph a
-Clause iv
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_21_a_iv&doctype=Standard
-URIDate 2023-03-23

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- Definition

The proportion of ownership interest in a subsidiary attributable to the entity. [Refer: Subsidiaries [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 17
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_17_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 16
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_16_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph 19B
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_19B_c&doctype=Standard
-URIDate 2023-03-23

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- Definition

The proportion of ownership interests in a subsidiary held by non-controlling interests. [Refer: Subsidiaries [member]; Non-controlling interests]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph 12
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_12_c&doctype=Standard
-URIDate 2023-03-23

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- Definition

Disclosure of significant investments in principal subsidiaries, associates and joint ventures.

+ References

No definition available.

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