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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 |  |  |  |

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- Definition Percentage of fair market value in the case of persons holding 10% or more of the voting stock of the company. + References No definition available. + Details
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- Definition Amount of intrinsic value of equity-based compensation awards not vested. + References No definition available. + Details
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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901 + Details
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- Definition Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901 + Details
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