Income Taxes - Reconciliation of U.S. Federal Statutory Tax Rate to Effective Tax Rate (Details)	12 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Operating Loss Carryforwards [Line Items]
U.S. federal statutory tax rate	21.00%	21.00%	21.00%
Difference in tax rate due to:
Goodwill impairment not deductible for tax	(7.30%)	0.00%	0.00%
Effects of foreign operations	3.90%	4.40%	4.60%
State income taxes, net of federal benefit	(1.10%)	1.50%	1.90%
Valuation allowance adjustments	1.10%	(0.50%)	1.00%
Other, net	0.40%	(0.10%)	(0.20%)
Effective tax rate	18.20%	22.60%	26.20%
Effects of U.S. tax legislation
Difference in tax rate due to:
Effects of tax rate changes	0.00%	0.00%	(0.80%)
Effects of tax rate changes - International
Difference in tax rate due to:
Effects of tax rate changes	0.00%	(2.30%)	(1.30%)
Effects of tax rate changes – State, net of federal benefit
Difference in tax rate due to:
Effects of tax rate changes	0.20%	(1.40%)	0.00%

Difference in tax rate due to.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

+ References

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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