Goodwill and other intangibles - Amortization (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Goodwill [member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	$ 1,879	$ 1,949
Increase (decrease) through net exchange differences, intangible assets and goodwill	1	(1)
Increase (Decrease) Through Finalization Of Purchase Price Allocation	(409)	(70)
Intangible assets other than goodwill at end of period	1,471	1,879
Customer-related intangible assets [member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	285	339
Amortization	47	53
Increase (decrease) through net exchange differences, intangible assets and goodwill	2
Intangible assets other than goodwill at end of period	239	285
Other intangible assets [member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	16	20
Additions	3	3
Amortization	2	9
Disposals	(4)
Other	2	(2)
Intangible assets other than goodwill at end of period	15	16
Goodwill And Intangible Assets Excluding Licenses [Member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	2,180	2,307
Additions	3	3
Amortization	49	63
Increase (decrease) through net exchange differences, intangible assets and goodwill	3	(1)
Increase (Decrease) Through Finalization Of Purchase Price Allocation	(409)	(70)
Disposals	(4)
Other	2	(2)
Intangible assets other than goodwill at end of period	1,726	2,180
Gross carrying amount \| Goodwill [member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	1,879
Intangible assets other than goodwill at end of period	1,471	1,879
Gross carrying amount \| Customer-related intangible assets [member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	489
Intangible assets other than goodwill at end of period	491	489
Gross carrying amount \| Other intangible assets [member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	81
Intangible assets other than goodwill at end of period	78	81
Gross carrying amount \| Goodwill And Intangible Assets Excluding Licenses [Member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	2,448
Intangible assets other than goodwill at end of period	2,040	2,448
Accumulated depreciation and amortisation \| Customer-related intangible assets [member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	(203)
Intangible assets other than goodwill at end of period	(251)	(203)
Accumulated depreciation and amortisation \| Other intangible assets [member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	(65)
Intangible assets other than goodwill at end of period	(63)	(65)
Accumulated depreciation and amortisation \| Goodwill And Intangible Assets Excluding Licenses [Member]
Reconciliation of changes in intangible assets other than goodwill [abstract]
Intangible assets other than goodwill at beginning of period	(268)
Intangible assets other than goodwill at end of period	$ (314)	$ (268)

The amount of additions to intangible assets other than goodwill, other than those acquired through business combinations. [Refer: Total for all business combinations [member]; Intangible assets other than goodwill]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 38
-IssueDate 2024-01-01
-Paragraph 118
-Subparagraph e
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=38&code=ifrs-tx-2024-en-r&anchor=para_118_e_i&doctype=Standard
-URIDate 2024-03-27

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- Definition

The amount of amortisation of intangible assets other than goodwill. [Refer: Depreciation and amortisation expense; Intangible assets other than goodwill]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 38
-IssueDate 2024-01-01
-Paragraph 118
-Subparagraph e
-Clause vi
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=38&code=ifrs-tx-2024-en-r&anchor=para_118_e_vi&doctype=Standard
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- Definition

The decrease in intangible assets and goodwill resulting from disposals. [Refer: Intangible assets and goodwill]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 38
-IssueDate 2024-01-01
-Paragraph 118
-Subparagraph e
-Clause ii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=38&code=ifrs-tx-2024-en-r&anchor=para_118_e_ii&doctype=Standard
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The increase (decrease) in intangible assets and goodwill resulting from the net exchange differences arising when the financial statements are translated from the functional currency into a different presentation currency, including the translation of a foreign operation into the presentation currency of the reporting entity. [Refer: Intangible assets and goodwill]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 38
-IssueDate 2024-01-01
-Paragraph 118
-Subparagraph e
-Clause vii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=38&code=ifrs-tx-2024-en-r&anchor=para_118_e_vii&doctype=Standard
-URIDate 2024-03-27

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- Definition

The increase (decrease) in intangible assets and goodwill resulting from changes that the entity does not separately disclose in the same statement or note. [Refer: Intangible assets and goodwill]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 38
-IssueDate 2024-01-01
-Paragraph 118
-Subparagraph e
-Clause viii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=38&code=ifrs-tx-2024-en-r&anchor=para_118_e_viii&doctype=Standard
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- Definition

The amount of intangible assets and goodwill held by the entity. [Refer: Goodwill; Intangible assets other than goodwill]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
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-IssueDate 2024-01-01
-Paragraph 55
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_55&doctype=Standard
-URIDate 2024-03-27

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- References

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Increase (Decrease) Through Finalization Of Purchase Price Allocation

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