Accumulated other comprehensive loss - Schedule of Reclassification Out of AOCI (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax benefit	$ 180	$ 156	$ 326	$ 280
Net income	(666)	(634)	(1,080)	(979)
Reclassification out of Accumulated Other Comprehensive Income \| Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of actuarial losses	6	4	11	8
Tax benefit	(2)	(2)	(3)	(3)
Net income	$ 4	$ 2	$ 8	$ 5

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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