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Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Jan. 06, 2017	Sep. 30, 2014
Product Warranty Expense	$ 12.3	$ 5.3	$ 5.1
Asset Retirement Obligation	3.8	7.5
Exposure to Workers Compensation Claims, Per Incident	1.0
Discontinued Operations, Receivable from Buyer of Discontinued Operation				$ 1.9	$ 11.8
Workers Compensation Undiscounted Basis Liability	10.7	13.7
Workers' Compensation Liability	$ 9.1	11.8
Income Tax Benefit, Likelihood of Realization Threshold	50.00%
Debt Issuance Costs, Net	$ 7.4
Minimum [Member]
Finite-Lived Tangible Asset, Useful Life, Maximum	3 years
Maximum [Member]
Finite-Lived Tangible Asset, Useful Life, Maximum	10 years
Land Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life, Minimum	10 years
Land Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life, Minimum	20 years
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life, Minimum	10 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life, Minimum	40 years
Machinery and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life, Minimum	3 years
Machinery and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life, Minimum	15 years
Software and Software Development Costs [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life, Minimum	6 years
U.S. Pipe [Member] | Maximum [Member]
Discontinued Operations, Receivable from Buyer of Discontinued Operation	$ 4.1
Other Current Assets [Member] | U.S. Pipe [Member]
Discontinued Operations, Receivable from Buyer of Discontinued Operation	0.5
Other Noncurrent Assets [Member] | U.S. Pipe [Member]
Discontinued Operations, Receivable from Buyer of Discontinued Operation	3.6
Revolving Credit Facility [Member]
Debt Issuance Costs, Net	1.5
Secured Debt [Member]
Debt Issuance Costs, Net	5.9	$ 6.3
Product Concentration Risk [Member]
Product Warranty Expense	$ 9.8

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