Income Taxes - Schedule of Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024
Unrecognized Tax Benefits [Roll Forward]
Balance at the beginning of the year	$ 81.3	$ 62.1
Gross increase in current period’s tax positions	9.2	34.5
Gross increase in prior years’ tax positions	47.0	13.9
Gross decrease in prior years’ tax positions	(6.4)	(20.1)
Decrease due to settlement with tax authorities	0.0	(7.4)
Decrease due to lapse of statute of limitations	(1.3)	(2.2)
Gross change due to foreign exchange fluctuations	(0.2)
Gross change due to foreign exchange fluctuations		0.5
Balance at the end of the year	$ 129.6	$ 81.3

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

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Amount of decrease in unrecognized tax benefits resulting from foreign currency translation.

+ References

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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