Pension and Other Post-Retirement Benefits - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plans, employer matching contribution, percentage	50.00%
Defined contribution plans, employer matching contribution of eligible salary, percentage	6.00%
Defined contribution plans, charges incurred	$ 0.5	$ 0.5	$ 0.7
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plans, pension expenses	0.5	0.5	0.9
Defined benefit plans, benefit obligation	11.8	10.4	14.7
Defined benefit plans, Net liability	$ 5.5	$ 4.9	$ 8.7

Amount of liability, recognized in statement of financial position, for defined benefit pension plan. Excludes other postretirement benefit plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(15))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 715
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-Section 45
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 50
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-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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Amount of cost for defined contribution plan.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Percentage employer matches of the employee's percentage contribution matched.

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Amount of cost (reversal of cost) for pension benefits. Excludes other postretirement benefits.

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