Income taxes - Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Income Tax Disclosure [Abstract]
Taxes calculated using the estimated annual effective tax rate	$ 229	$ 166
Discrete tax items	(60)	(69)
Provision for income taxes	$ 169	$ 97
Effective tax rate	10.00%	8.00%