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, 2021	Dec. 31, 2020	Dec. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net (OI&E)		$ 143	$ 313	$ 175
Provision for income taxes		(1,150)	(422)	(711)
Net income		7,769	5,595	5,017
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]	37	38	51
Provision for income taxes		(8)	(9)	(13)
Net income		29	29	38
Reclassification out of Accumulated Other Comprehensive Income | Prior service credit of defined benefit plans:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net (OI&E)	[1]	(1)	(1)	0
Provision for income taxes		0	0	0
Net income		$ (1)	$ (1)	$ 0

[1] Detailed in Note 7.