Stockholders' equity - Summary of Stock Repurchase Program Activity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended	12 Months Ended
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
Equity [Abstract]
Stock repurchases (in shares)	0.0	0.0	0.0	0.0	0.0	1.5	0.0	24.6	6.9	4.6	6.5	3.7	0.0	26.1	21.7
Stock repurchases	$ 0	$ 0	$ 0	$ 0	$ 0	$ 900	$ 0	$ 5,410	$ 1,461	$ 1,069	$ 1,592	$ 865	$ 0	$ 6,310	$ 4,987

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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