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Organization (Narrative) (Details) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2025 USD ($) business_segments	Mar. 31, 2025 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)
Segment Reporting Information [Line Items]
Restructuring	$ 2.1	$ 2.1	$ 7.2	$ 3.4	$ 6.6
Restructuring Reserve, Accrual Adjustment		4.1	$ 9.8
Number of Reportable Segments | business_segments	2
Other Sundry Liabilities, Noncurrent	$ 3.9	3.9
Proceeds from Other Equity, Gross Amount	4.8	4.8
Intercompany Loan related to NMTC	12.2	12.2
Investment Fund Contribution for NMTC	16.5	16.5
Sub-CDE loan from NMTC	$ 16.2	$ 16.2

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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

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