Income taxes (Details 7) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Unrecognized tax benefits, beginning	$ 1,759	$ 1,778	$ 1,796
Additions for tax positions related to current year	141	44	72
Additions for tax positions related to prior years	43	46	112
Reductions for tax positions related to prior years	(30)	(12)	(201)
Reductions for settlements	(24)	(94)	0
Reductions for expiration of statute of limitations	(3)	(3)	(1)
Unrecognized tax benefits, ending	1,886	1,759	1,778
Unrecognized tax benefits that, if recognized, would impact the effective tax rate	1,688	1,657	1,616
Net provision for interest and penalties	54	38	$ 43
Interest and penalties, accrued	297	$ 264
Income tax examination, proposed liability increase/(decrease)	$ 2,300