Stockholders' equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended													3 Months Ended												12 Months Ended
	Dec. 12, 2023	Mar. 31, 2024	Oct. 31, 2023	Jul. 31, 2023	Mar. 31, 2023	Dec. 31, 2022	Oct. 31, 2022	Jul. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Oct. 31, 2021	Jul. 31, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Stock repurchases															$ 0	$ 0	$ 0	$ 0	$ 0	$ 900	$ 0	$ 5,410	$ 1,461	$ 1,069	$ 1,592	$ 865	$ 0	$ 6,310	$ 4,987
Stock repurchases (in shares)															0	0	0	0	0	1,500,000	0	24,600,000	6,900,000	4,600,000	6,500,000	3,700,000	0	26,100,000	21,700,000
Amount available for stock repurchases under a board approved stock repurchase plan															$ 7,000												$ 7,000
Common stock, dividends declared per share (in usd per share)	$ 2.25		$ 2.13	$ 2.13	$ 2.13	$ 2.13	$ 1.94	$ 1.94	$ 1.94	$ 1.94	$ 1.76	$ 1.76	$ 1.76	$ 1.76													$ 8.64	$ 7.95	$ 7.22
Common stock, dividends paid per share (in usd per share)															$ 2.13	$ 2.13	$ 2.13	$ 2.13	$ 1.94	$ 1.94	$ 1.94	$ 1.94	$ 1.76	$ 1.76	$ 1.76	$ 1.76
Income taxes expense or (benefit) for unrealized gains and losses for cash flow hedges																											$ 6	$ (19)	$ (33)
Income taxes expense or (benefit) for unrealized gains and losses for cash flow hedges and related reclassifications																											$ 50	$ 0	$ (55)
Preferred stock shares authorized (in shares)															5,000,000												5,000,000
Preferred stock, par value (in usd per share)															$ 0.0001												$ 0.0001
Preferred stock, shares outstanding (in shares)						0									0				0								0	0
Preferred stock, shares issued (in shares)						0									0				0								0	0
Forecast
Class of Stock [Line Items]
Common stock, dividends paid per share (in usd per share)		$ 2.25
Accelerated stock repurchase agreement
Class of Stock [Line Items]
Stock repurchases																						$ 6,000
Stock repurchases (in shares)																						23,300,000						24,800,000