Supplemental financial information - Amounts Reclassified out of AOCI (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense), net (OI&E)		$ 99	$ 52	$ 124	$ 88
Provision for income taxes		101	(209)	51	(369)
Net income		1,380	1,305	2,554	2,522
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]	9	15	19	28
Provision for income taxes		(3)	(4)	(5)	(7)
Net income		$ 6	$ 11	$ 14	$ 21

[1] Detailed in Note 6.