Stock Award Plans - Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Number of Options
Outstanding, beginning balance (in shares)	1,137,608	1,030,323
Granted (in shares)	779,740	352,043	0
Exercised (in shares)	(35,877)	(64,415)
Forfeited (in shares)	(173,646)	(180,343)
Outstanding, ending balance (in shares)	1,707,825	1,137,608	1,030,323
Exercisable (in shares)	318,695
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 30.06	$ 29.14
Granted (in dollars per share)	28.47	32.49
Exercised (in dollars per share)	30.39	28.16
Forfeited (in dollars per share)	30.07	30.24
Outstanding, ending balance (in dollars per share)	29.32	$ 30.06	$ 29.14
Exercisable (in dollars per share)	$ 33.15
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, weighted average remaining contractual term (in years)	8 years	8 years	8 years
Options outstanding, aggregate intrinsic value	$ 0	$ 0	$ 5,330
Weighted average remaining contractual term, Exercisable	7 years
Aggregate intrinsic value, exercisable	$ 0

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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