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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Basic EPS:
Net income	$ 1,362	$ 1,709	$ 3,594	$ 5,139
Income allocated to RSUs	(7)	(9)	(18)	(27)
Income allocated to common stock	$ 1,355	$ 1,700	$ 3,576	$ 5,112
Weighted average number of shares outstanding, basic (in shares)	913	908	912	908
Basic (in dollars per share)	$ 1.48	$ 1.87	$ 3.92	$ 5.63
Dilutive effect of stock compensation plans (in shares)	7	8	7	8
Diluted EPS:
Net income	$ 1,362	$ 1,709	$ 3,594	$ 5,139
Income allocated to RSUs	(7)	(10)	(18)	(26)
Income allocated to common stock for diluted EPS	$ 1,355	$ 1,699	$ 3,576	$ 5,113
Weighted average number of shares outstanding, diluted (in shares)	920	916	919	916
Diluted (in dollars per share)	$ 1.47	$ 1.85	$ 3.89	$ 5.58