Schedule II - Valuation Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Deducted from Receivables — Allowance for Credit Losses
Valuation Reserves [Roll Forward]
Balance at the Beginning of the Period	$ 3.6	$ 2.3	$ 3.4
Additions Charged to Expense	3.5	3.5	2.2
Deductions	(4.9)	(2.2)	(3.3)
Balance at the End of the Period	2.2	3.6	2.3
Deducted from Deferred Income Taxes — Valuation Allowance
Valuation Reserves [Roll Forward]
Balance at the Beginning of the Period	167.3	121.2	109.9
Additions Charged to Expense	33.1	46.2	12.1
Deductions	(1.5)	(0.1)	(0.8)
Balance at the End of the Period	$ 198.9	$ 167.3	$ 121.2