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Organization (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2024 USD ($) business_segments	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Segment Reporting Information [Line Items]
Restructuring	$ 4.1	$ 2.2	$ 4.1	$ 2.2	$ 6.6	$ 3.3
Restructuring Reserve, Accrual Adjustment			12.7	0.9
Gain (Loss) on Sale of Properties				4.0
Pension costs (benefits) other then service	$ 1.0	$ 0.9	$ 3.0	$ 2.8
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
Number of Reportable Segments | business_segments	2
Other Sundry Liabilities, Noncurrent	$ 3.9		$ 3.9
Asset Impairment Charges			1.4	$ 0.0
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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