INCOME TAXES - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits, beginning of year	$ 190.2	$ 121.1	$ 100.9
Gross increase – tax positions in prior period	3.2	77.5	21.5
Gross decrease – tax positions in prior period	(6.7)	(9.2)	(34.4)
Gross increase – tax positions in current period	1.4	1.7	33.4
Settlements	0.0	(0.6)	0.0
Lapse of statutes of limitations	(1.8)	(0.3)	(0.3)
Unrecognized tax benefits, end of year	$ 186.3	$ 190.2	$ 121.1

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 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 increase 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 lapses of applicable statutes of limitations.

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