Income taxes - Schedule of unrecognized tax benefits roll forward (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Unrecognized Tax Benefits [Roll Forward]
Balance beginning of the year	$ 19,185	$ 13,383	$ 7,437
Increases related to tax positions during the year	3,354	5,043	5,082
Increases related to tax positions taken in the prior year		759	864
decreases related to tax positions taken in the prior year	(127)
Balance end of the year	$ 22,412	$ 19,185	$ 13,383

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

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 217
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-217

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15A
-Subparagraph (a)
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 10B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482525/740-10-45-10B

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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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