Share-based compensation - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended		12 Months Ended
	Dec. 31, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Jun. 11, 2020	Jun. 07, 2018	Sep. 17, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Common stock reserved for issuance		4,743,801
Stock option vesting period		2 years
Share-based compensation arrangement by share based payment award percentage of fair market Person holding more then 10% voting stock		110.00%
Intrinsic value of options outstanding	$ 8.9	$ 15.2		$ 8.9
Intrinsic value of options unvested	$ 0.0	0.6		$ 0.0
Intrinsic value of options exercised		$ 2.1	$ 1.6
Minimum
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Options outstanding		3 years
Maximum
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Options outstanding		10 years
2014 Stock Incentive Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Common stock reserved for issuance							3,000,000
2018 Stock Incentive Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Common stock reserved for issuance						4,000,000
2020 Stock Incentive Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Common stock reserved for issuance					3,000,000
Stock Option Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Options granted		379,070		484,254
Option to purchase granted				463,754
Share-based awards at the granted
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Options granted		379,070	463,754
Stock Appreciation Rights (SARs)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Options granted	20,500
Selling, general and administrative expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share based compensation expense		$ 0.8	$ 0.4