Derivative and hedging activities - Effect on AOCI (Details) - Net Investment Hedging - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of gain or (loss) recognized in OCI on Derivative	$ 7.3	$ 6.8	$ 29.8	$ (93.9)
Amount of gain or (loss) recognized in income on Derivative (amount excluded from effectiveness testing)	1.7	1.9	5.2	7.2
Cross-currency swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of gain or (loss) recognized in OCI on Derivative	7.3	6.8	29.8	(93.9)
Cross-currency swaps | Income Statement Location [Axis]: us-gaap:InterestExpense
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of gain or (loss) recognized in income on Derivative (amount excluded from effectiveness testing)	$ 1.7	$ 1.9	$ 5.2	$ 7.2