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Organization (Details) $ in Millions |  | 3 Months Ended | 6 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | ---
Jul. 31, 2014 | Jun. 30, 2018 USD ($) | Dec. 31, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Mar. 31, 2017 USD ($) | Jun. 30, 2018 USD ($) | Jun. 30, 2017 USD ($) | Sep. 30, 2019 | Sep. 30, 2017
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Beginning balance |  |  | $ 3.3 |  |  |  | $ 3.3 |  |  |
Restructuring |  | $ 2.6 |  | $ 1.2 |  |  | 8.4 | $ 5.0 |  |
Payments |  |  | $ 6.3 |  |  |  |  |  |  |
Number of Reportable Segments |  |  | 2 |  |  |  |  |  |  |
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage | 49.00% |  |  |  |  |  |  |  |  |
Payments for (Proceeds from) Other Investing Activities |  |  |  |  |  | $ 26.6 |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost other than Service Cost |  | 0.2 |  | 0.4 |  |  | 0.7 | 1.1 |  |
Revenue, Net |  | $ 250.2 |  | $ 232.2 |  |  | $ 661.7 | $ 599.1 |  |
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent |  | 24.50% |  | 35.00% |  |  | 24.50% | 35.00% |  | 35.00%
Mueller Co. [Member] |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Restructuring |  | $ 0.0 |  | $ 0.4 |  |  | $ 0.1 | $ 2.1 |  |
Revenue, Net |  | $ 224.1 |  | $ 207.6 |  |  | $ 595.3 | $ 535.5 |  |
General and Administrative Expense [Member] | Mueller Co. [Member] |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost other than Service Cost |  |  |  |  | $ 0.3 | 0.8 |  |  |  |
Cost of Sales [Member] | Mueller Co. [Member] |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost other than Service Cost |  |  |  |  | $ 0.1 | $ 0.3 |  |  |  |
Scenario, Forecast [Member] |  |  |  |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |  |  |  |
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent |  |  |  |  |  |  |  |  | 21.00% |

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