Stockholders' equity - Schedule of Changes in Stockholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	$ 16,897
Net income	1,105	$ 1,708
Other comprehensive income (loss), net of taxes	2	2
Balance, ending	16,983
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	1,741	1,741
Balance, ending	1,741	1,741
Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	3,362	2,951
Common stock issued for stock-based awards	(29)	(37)
Stock compensation	106	104
Other	0	(2)
Balance, ending	3,439	3,016
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	52,283	50,353
Net income	1,105	1,708
Dividends declared and paid	(1,183)	(1,125)
Dividend equivalents on RSUs	(7)	(6)
Other	1	0
Balance, ending	52,199	50,930
Treasury Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	(40,284)	(40,214)
Common stock issued for stock-based awards	94	118
Stock repurchases	(3)	(96)
Balance, ending	(40,193)	(40,192)
AOCI
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	(205)	(254)
Other comprehensive income (loss), net of taxes	2	2
Balance, ending	$ (203)	$ (252)