Stock-based compensation - Narrative (Details) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2022 USD ($) shares
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period for recognition	1 year 11 months 19 days
Shares withheld (in shares) \| shares	0.1
Tax withholding obligation	$ 1.0
Unrecognized compensation expense, excluding options	$ 11.3
Performance stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period for recognition	11 months 1 day
Shares withheld (in shares) \| shares	0.1
Tax withholding obligation	$ 0.8
Unrecognized compensation expense, excluding options	$ 24.0
Performance factor percentage	148.00%
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, options	$ 0.1
2018 Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period for recognition	1 year 5 months 8 days
2020 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, options	$ 9.4
Remaining shares available for grant (in shares) \| shares	9.6
2020 Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period for recognition	2 years 10 months 24 days

Share-based Compensation Arrangement by Share-based Payment Award, Performance Goal

No definition available.

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- Definition

Amount of decrease to equity for grantee's tax withholding obligation for award under share-based payment arrangement.

+ References

No definition available.

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- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Number of shares used to settle grantee's tax withholding obligation for award under share-based payment arrangement.

+ References

No definition available.

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