Income taxes - Schedule of Effective Income Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S. statutory rate	$ 843	$ 727	$ 651
State tax, net of federal tax benefit	38	73	61
Tax rate differentials	(11)	(6)	4
Uncertain tax positions	87	60	75
Tax credits	(125)	(96)	(107)
Non-deductible goodwill impairment	75	0	0
Other	18	4	(34)
Total tax expense	$ 925	$ 762	$ 650
Effective income tax rate	23.00%	22.00%	21.00%