Other assets - Narratives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Deferred Costs Capitalized Prepaid And Other Assets Disclosure Abstract
Hosting arrangement service contract implementation cost capitalized	$ 22.1		$ 22.1		$ 18.4
Hosting arrangement service contract accumulated amortization	10.8		10.8		8.8
Hosting arrangement service contract, net value	11.3		11.3		$ 9.6
Hosting arrangement service amortization expense	$ 1.1	$ 1.1	$ 2.0	$ 1.9