Basis of presentation and significant accounting policies and practices - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Basic EPS:
Net income	$ 2,295	$ 1,947	$ 6,787	$ 5,631
Income allocated to RSUs	(11)	(9)	(30)	(23)
Income allocated to common stock	$ 2,284	$ 1,938	$ 6,757	$ 5,608
Weighted average number of shares outstanding, basic (in shares)	913	923	919	923
Basic (in dollars per share)	$ 2.50	$ 2.10	$ 7.35	$ 6.08
Dilutive effect of stock compensation plans (in shares)	10	13	10	13
Diluted EPS:
Net income	$ 2,295	$ 1,947	$ 6,787	$ 5,631
Income allocated to RSUs	(11)	(9)	(30)	(24)
Income allocated to common stock for diluted EPS	$ 2,284	$ 1,938	$ 6,757	$ 5,607
Weighted average number of shares outstanding, diluted (in shares)	923	936	929	936
Diluted (in dollars per share)	$ 2.47	$ 2.07	$ 7.27	$ 5.99