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Segment Information (Narrative) (Details) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2015 USD ($) business_segments customer | Sep. 30, 2014 USD ($) | Sep. 30, 2013 | Sep. 30, 2012
Segment Reporting [Abstract] |  |  |  |
Number of Reportable Segments | business_segments | 3 |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Receivables, net | $ 175.3 | $ 182.1 |  |
Customer Concentration Risk [Member] | Major Customers, Group One |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Number of major customers | customer | 10 |  |  |
Customer Concentration Risk [Member] | Major Customers, Group One | Sales Revenue, Goods, Gross [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Concentration risk, percentage of benchmark | 41.00% |  |  |
Customer Concentration Risk [Member] | Major Customers, Group Two |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Number of major customers | customer | 2 |  |  |
Customer Concentration Risk [Member] | Major Customers, Group Two | Sales Revenue, Goods, Gross [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Concentration risk, percentage of benchmark | 25.00% |  |  |
Customer Concentration Risk [Member] | Ferguson Enterprises | Sales Revenue, Goods, Gross [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Concentration risk, percentage of benchmark | 13.00% | 13.00% | 12.00% |
Customer Concentration Risk [Member] | Ferguson Enterprises | Sales Revenue, Goods, Gross [Member] | Mueller Co. [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Concentration risk, percentage of benchmark | 16.00% |  |  |
Customer Concentration Risk [Member] | Ferguson Enterprises | Sales Revenue, Goods, Gross [Member] | Anvil [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Concentration risk, percentage of benchmark | 8.00% |  |  |
Customer Concentration Risk [Member] | Ferguson Enterprises | Accounts Receivable [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Receivables, net | $ 28.2 | $ 25.7 |  |
Customer Concentration Risk [Member] | HD Supply | Sales Revenue, Goods, Gross [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Concentration risk, percentage of benchmark | 12.00% | 11.00% |  | 11.00%
Customer Concentration Risk [Member] | HD Supply | Sales Revenue, Goods, Gross [Member] | Mueller Co. [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Concentration risk, percentage of benchmark | 18.00% |  |  |
Customer Concentration Risk [Member] | HD Supply | Sales Revenue, Goods, Gross [Member] | Anvil [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Concentration risk, percentage of benchmark | 5.00% |  |  |
Customer Concentration Risk [Member] | HD Supply | Accounts Receivable [Member] |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |
Receivables, net | $ 17.4 | $ 17.7 |  |

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