Stock-based compensation - Restricted Stock Units and Other Stock Awards (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Unvested restricted stock units
Number of Shares
Unvested at beginning of period (in shares)	3,834,108
Granted (in shares)	2,457,489
Vested (in shares)	(1,634,811)
Forfeited (in shares)	(723,754)
Unvested at end of period (in shares)	3,933,032	3,834,108
Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted-average remaining contractual term	1 year 4 months 24 days	1 year 4 months 24 days
Aggregate intrinsic value (in dollars)	$ 5,624	$ 8,895
Weighted-Average Grant Date Fair Value
Unvested at beginning of period (in dollars per share)	$ 5.01
Granted (in dollars per share)	2.99
Vested (in dollars per share)	4.88
Forfeited (in dollars per share)	4.37
Unvested at end of period (in dollars per share)	$ 3.91	$ 5.01
Rescinded Restricted Stock Unit (RSU)
Number of Shares
Forfeited (in shares)	(14,467)

No definition available.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

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-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 718
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-Name Accounting Standards Codification
-Paragraph 2
-Section 50
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Intrinsic value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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