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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Basic EPS:
Net income	$ 1,722	$ 2,291	$ 3,430	$ 4,492
Income allocated to RSUs	(9)	(10)	(17)	(19)
Income allocated to common stock	$ 1,713	$ 2,281	$ 3,413	$ 4,473
Weighted average number of shares outstanding, basic (in shares)	908	920	907	922
Basic (in dollars per share)	$ 1.89	$ 2.48	$ 3.76	$ 4.85
Dilutive effect of stock compensation plans (in shares)	8	10	9	10
Diluted EPS:
Net income	$ 1,722	$ 2,291	$ 3,430	$ 4,492
Income allocated to RSUs	(8)	(10)	(18)	(19)
Income allocated to common stock for diluted EPS	$ 1,714	$ 2,281	$ 3,412	$ 4,473
Weighted average number of shares outstanding, diluted (in shares)	916	930	916	932
Diluted (in dollars per share)	$ 1.87	$ 2.45	$ 3.72	$ 4.80