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Supplemental Statement of Operations Information (Details) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016
Schedule of Statement of Operations Supplemental Disclosures [Line Items] |  |  |
Restructuring Reserve | $ 0.9 | $ 3.3 |
Included in selling, general and administrative expenses: |  |  |
Research and development | 11.6 | 12.1 | $ 9.9
Advertising | 7.1 | 5.2 | 4.0
Interest expense, net: |  |  |
Interest rate swap contracts | 0.6 | 1.9 | 0.0
Deferred financing fees amortization | 1.6 | 1.8 | 1.9
Other interest expense | 0.6 | 0.6 | 0.5
Interest Expense | 25.3 | 24.2 | 24.0
Interest income | (4.4) | (2.0) | (0.4)
Interest expense, net | (20.9) | (22.2) | (23.6)
Other Cost and Expense, Operating | 10.5 | 10.4 | 7.2
Secured Debt [Member] |  |  |
Interest expense, net: |  |  |
Debt instrument interest expense | 14.4 | 19.1 | 20.5
Seven Point Three Seven Five Senior Subordinated Notes [Member] |  |  |
Interest expense, net: |  |  |
Debt instrument interest expense | 7.5 | 0.0 | 0.0
ABL Agreement [Member] |  |  |
Interest expense, net: |  |  |
Debt instrument interest expense | $ 0.6 | 0.8 | 1.1
Statesboro [Member] |  |  |
Interest expense, net: |  |  |
Other Cost and Expense, Operating |  |  | $ 4.1
Mueller One Project [Member] |  |  |
Interest expense, net: |  |  |
Other Cost and Expense, Operating |  | $ 4.6 |

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