Organization (Details) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2022 USD ($) business_segments	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Segment Reporting Information [Line Items]
Restructuring	$ 0.5	$ 2.6	$ 0.5	$ 2.6	$ 3.1	$ 2.8
Restructuring and other charges	0.6	3.9	3.6	6.1
Payments			3.0	2.2
Pension costs (benefits) other then service	$ (0.9)	$ (0.8)	$ (2.9)	$ (2.4)
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
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
Mueller Co. [Member]
Segment Reporting Information [Line Items]
Restructuring and other charges	$ 0.0	$ 0.0	$ 0.0	$ 0.1

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