Commitments and contingencies (Details) - USD ($) $ in Billions	3 Months Ended	9 Months Ended
	Mar. 31, 2025	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Letter of credit
Other Commitments [Line Items]
Debt instrument, term	1 year	1 year	1 year
Financial guarantee
Other Commitments [Line Items]
Guarantor obligations, current carrying value		$ 17.8	$ 12.9	$ 13.1
Financial standby letter of credit
Other Commitments [Line Items]
Guarantor obligations, current carrying value		$ 0.5	$ 0.5	$ 0.4