Income Taxes - Reconciliation of U.S. Federal Statutory Tax Rate to Effective Tax Rate (Details)	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
U.S. federal statutory tax rate	24.50%	35.00%	35.00%
Difference in tax rate due to:
Effect of tax rate changes - TJCA	(20.90%)	0.00%	0.00%
Effect of tax rate changes - France	(2.10%)	(4.10%)	0.00%
Noncontrolling interests not subject to tax	(3.00%)	(4.30%)	(6.20%)
State income taxes, net of federal benefit	2.90%	2.90%	3.00%
Valuation allowance adjustments	1.10%	(1.10%)	(0.90%)
Effects of foreign operations	3.10%	(1.10%)	0.60%
Excess tax benefits on share-based payments	(1.10%)	(1.30%)	0.00%
Other, net	(0.70%)	(0.70%)	(0.30%)
Effective tax rate	3.80%	25.30%	31.20%

Difference in tax rate due to.

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Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Percent

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Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act of 2017, 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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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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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 attributable to noncontrolling interest income (loss) exempt from income taxes.

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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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