Stockholders' equity - Schedule of Changes in Stockholders' Equity (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning		$ 16,897			$ 16,897
Net income	$ 1,127		$ 1,722		2,232	$ 3,430
Other comprehensive income (loss), net of taxes	3		6		5	8
Balance, ending	17,214				17,214
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	1,741	1,741	1,741	$ 1,741	1,741	1,741
Balance, ending	1,741	1,741	1,741	1,741	1,741	1,741
Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	3,439	3,362	3,016	2,951	3,362	2,951
Common stock issued for stock-based awards	111	(29)	36	(37)
Stock compensation	116	106	111	104
Other		0		(2)
Balance, ending	3,666	3,439	3,163	3,016	3,666	3,163
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	52,199	52,283	50,930	50,353	52,283	50,353
Net income	1,127	1,105	1,722	1,708
Dividends declared and paid	(1,185)	(1,183)	(1,125)	(1,125)
Dividend equivalents on RSUs	(6)	(7)	(5)	(6)
Other		1		0
Balance, ending	52,135	52,199	51,522	50,930	52,135	51,522
Treasury Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	(40,193)	(40,284)	(40,192)	(40,214)	(40,284)	(40,214)
Common stock issued for stock-based awards	137	94	29	118
Stock repurchases	(72)	(3)	(77)	(96)
Balance, ending	(40,128)	(40,193)	(40,240)	(40,192)	(40,128)	(40,240)
AOCI
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning	(203)	(205)	(252)	(254)	(205)	(254)
Other comprehensive income (loss), net of taxes	3	2	6	2
Balance, ending	$ (200)	$ (203)	$ (246)	$ (252)	$ (200)	$ (246)