Income taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
(Decreases) increases in taxes resulting from:
Taxes at U.S. statutory rate	$ 1,641	$ 1,643	$ 1,429
Taxes at U. S. statutory rate (as a percent)	21.00%	21.00%	35.00%
Non-U.S. subsidiaries taxed at other than the U.S. rate	$ 365	$ 282	$ (282)
Non-U.S. subsidiaries taxed at other than the U.S. rate (as a percent)	4.70%	3.60%	(6.90%)
State and local taxes, net of federal	$ 59	$ 22	$ 27
State and local taxes, net of federal (as a percent)	0.80%	0.30%	0.70%
Interest and penalties, net of tax	$ 34	$ 33	$ 28
Interest and penalties, net of tax (as a percent)	0.40%	0.40%	0.70%
U.S. tax incentives	$ (149)	$ (106)	$ (52)
U.S. tax incentives (as a percent)	(1.90%)	(1.30%)	(1.30%)
Net excess tax benefits from stock-based compensation	$ (41)	$ (56)	$ (64)
Net excess tax benefits from stock-based compensation, percent	(0.50%)	(0.70%)	(1.60%)
U.S. deferred tax rate change	$ 0	$ (154)	$ 596
U.S. deferred tax rate change (as a percent)	0.00%	(2.00%)	14.60%
Mandatory deemed repatriation of non-U.S. earnings	$ (178)	$ 50	$ 1,775
Mandatory deemed repatriation of non-U.S. earnings (as a percent)	(2.30%)	0.70%	43.50%
Valuation allowances	$ 0	$ (29)	$ (111)
Valuation allowances (as a percent)	0.00%	(0.40%)	(2.70%)
Other-net	$ 15	$ 13	$ (7)
Other-net (as a percent)	0.20%	0.10%	(0.20%)
Provision (benefit) for income taxes	$ 1,746	$ 1,698	$ 3,339
Provision (benefit) for income taxes (as a percent)	22.40%	21.70%	81.80%
U.S. state taxing jurisdictions
(Decreases) increases in taxes resulting from:
Valuation allowances			$ (111)