Income Taxes - Effective Rate Reconciliation (Details)	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Federal statutory rate effect of:	21.00%	21.00%	21.00%
U.S. State and local income taxes	1.80%	1.20%	(0.90%)
Foreign earnings and losses taxed at different rates	1.00%	0.90%	0.20%
Change in valuation allowance	1.90%	1.00%	0.90%
Income tax rate holiday	(0.50%)	(0.80%)	0.50%
U.S. permanent items	(1.20%)	0.60%	(0.50%)
Non-deductible compensation	1.90%	0.60%	0.70%
Foreign permanent items	(0.20%)	1.10%	0.20%
U.S. bargain purchase gain	(0.50%)	(8.30%)	(1.00%)
GILTI	0.60%	0.70%	2.20%
Income tax rate change	(1.20%)	0.00%	0.00%
Income tax rate change	24.60%	18.00%	23.30%

Effective Income Tax Rate Reconciliation, Permanent Items, Percent

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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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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.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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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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