Financial instruments and concentration of credit risks - Gains and Losses Recognized on Foreign Exchange Forward Contracts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other (expense), net | Foreign Exchange Forward Contract
Fair Value, Gain (Loss) Included in Earnings, Measured on Recurring Basis [Line Items]
Amount of gain (loss) recognized	$ (18.8)	$ 7.6	$ 1.7