Stockholders' Equity - Performance RSU Activity (Details) - Performance RSUs - $ / shares	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Number of Shares
Beginning balance (in shares)	353,556	1,722,551	2,042,817
Granted (in shares)	284,765	353,556	0
Exercised (in shares)	(90,345)	0	0
Canceled (in shares)	(19,252)	(1,722,551)	(320,266)
Ending balance (in shares)	528,724	353,556	1,722,551
Weighted- Average Fair Value Per Share
Beginning balance (in dollars per share)	$ 6.06	$ 7.76	$ 7.66
Granted (in dollars per share)	11.84	6.06	0
Exercised (in dollars per share)	6.06	0	0
Canceled (in dollars per share)	6.06	7.76	7.11
Ending balance (in dollars per share)	$ 9.17	$ 6.06	$ 7.76

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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- Definition

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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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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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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No definition available.

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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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- Definition

Number of non-option equity instruments exercised by participants.

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Number of shares under non-option equity instrument agreements that were cancelled as a result of occurrence of a terminating event.

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Net number of non-option equity instruments granted to participants.

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Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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