Supplemental financial information - Amounts reclassified out of accumulated other comprehensive income (loss), net of taxes, to net income (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net (OI&E)		$ 440	$ 106	$ 143
Provision for income taxes		(908)	(1,283)	(1,150)
Net income		6,510	8,749	7,769
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]	20	78	37
Provision for income taxes		(5)	(17)	(8)
Net income		15	61	29
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]	1	(1)	(1)
Provision for income taxes		0	0	0
Net income		$ 1	$ (1)	$ (1)

[1] Detailed in Note 7