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Share-Based Compensation - Schedule of Restricted Stock Activity (Detail) - Restricted Stock [Member] - 2018 Equity Incentive Plan [Member] - $ / shares		1 Months Ended		12 Months Ended
	Aug. 14, 2018	Apr. 30, 2019	Jul. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance				1,195,548	847,974	1,250,625
Number of Shares, Granted	1,266,034	3,827,493		346,123	910,297	321,926
Number of Shares, Vested		(2,748,042)		(492,465)	(555,473)	(701,582)
Number of Shares, Cancelled		(73,245)	(491,915)	(43,000)	(7,250)	(22,995)
Number of Shares, Unvested, Ending Balance				1,006,206	1,195,548	847,974
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance				$ 5.47	$ 9.56	$ 9.59
Weighted-Average Grant Date Fair Value, Granted				9.53	3.97	8.94
Weighted-Average Grant Date Fair Value, Vested				6.89	9.21	9.25
Weighted-Average Grant Date Fair Value, Cancelled				4.57	7.89	12.00
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance				$ 6.22	$ 5.47	$ 9.56

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- Definition

Share based compensation arrangement by share based payment award equity instruments other than options cancelled in period.

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Share based compensation arrangement by share based payment award equity instruments other than options cancelled weighted average grant date fair value.

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- Definition

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).

+ 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
-Subparagraph (c)(2)(iii)(1)
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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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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.

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

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- Definition

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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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.

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