Supplemental financial information - Amounts Reclassified out of AOCI (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net (OI&E)		$ 62	$ 131	$ 190	$ 384
Provision for income taxes		(220)	(192)	(500)	(500)
Net income		1,364	1,362	3,838	3,594
Reclassification out of Accumulated Other Comprehensive Income | Net actuarial losses of defined benefit plans:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net (OI&E)	[1]	6	3	14	10
Provision for income taxes		(1)	(1)	(3)	(3)
Net income		5	2	11	7
Reclassification out of Accumulated Other Comprehensive Income | Prior service cost (credit) of defined benefit plans:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net (OI&E)	[1]	0	1	0	1
Provision for income taxes		0	0	0	0
Net income		$ 0	$ 1	$ 0	$ 1

[1] Detailed in Note 5