Financial instruments and concentration of credit risks - Fair Value of Foreign Exchange Forward Contracts by Balance Sheet Location (Details) - Foreign Exchange Forward Contract - Level 2 - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Prepaid expenses and other current assets	$ 9.0	$ 7.9
Other accrued liabilities	0.1	1.3
Total fair value	$ 8.9	$ 6.6