Earnings per share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income (Numerator):
Net income for basic and diluted EPS	$ 5,893	$ 7,264	$ 7,842
Shares (Denominator):
Weighted-average shares for basic EPS	570	586	605
Effect of dilutive securities (in shares)	3	4	4
Weighted-average shares for diluted EPS	573	590	609
Basic EPS (in usd per share)	$ 10.34	$ 12.40	$ 12.96
Diluted EPS (in usd per share)	$ 10.28	$ 12.31	$ 12.88