Stock-based compensation (Components of Stock-based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of stock-based compensation expense [Abstract]
Total stock-based compensation expense, pretax	$ 341	$ 330	$ 308
Tax benefit from stock-based compensation expense	(74)	(72)	(67)
Total stock-based compensation expense, net of tax	267	258	241
RSUs [Member]
Components of stock-based compensation expense [Abstract]
Total stock-based compensation expense, pretax	183	178	168
Performance units [Member]
Components of stock-based compensation expense [Abstract]
Total stock-based compensation expense, pretax	121	118	105
Stock options [Member]
Components of stock-based compensation expense [Abstract]
Total stock-based compensation expense, pretax	$ 37	$ 34	$ 35