Retirement benefits - Impact of change in assumptions (Details) $ in Millions	Dec. 31, 2025 USD ($)
Actuarial assumption of discount rates
Disclosure of defined benefit plans [line items]
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption	$ (58)
Increase (decrease) in defined benefit obligation due to reasonably possible decrease in actuarial assumption	70
Actuarial assumption of expected rates of salary increases
Disclosure of defined benefit plans [line items]
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption	15
Increase (decrease) in defined benefit obligation due to reasonably possible decrease in actuarial assumption	$ (11)

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

No definition available.

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- Definition

The increase (decrease) in a defined benefit obligation that would have been caused by a decrease in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [domain]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2024-01-01
-Paragraph 145
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_145_a&doctype=Standard
-URIDate 2024-03-27

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- Definition

The increase (decrease) in a defined benefit obligation that would have been caused by an increase in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [domain]]

+ References

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