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Discontinued Operations, Assets Held for Sale and Divestitures (Details) - USD ($) $ in Millions		3 Months Ended								6 Months Ended	12 Months Ended
	Apr. 02, 2012	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Restructuring Charges											$ 9.2	$ 3.1	$ 1.5
Asset Impairment Charges											11.6	0.0	0.0
Revenue, Net		$ 311.4	$ 301.0	$ 290.3	$ 261.8	$ 320.7	$ 318.5	$ 288.1	$ 257.4		1,164.5	1,184.7	$ 1,120.8
Multiemployer Plans, Withdrawal Obligation		$ 0.9									0.9
Gain (Loss) on Sale of Assets and Asset Impairment Charges											2.5
QUEBEC
Restructuring Charges											7.2
Asset Impairment Charges											2.5
Environmental Remediation Expense											2.3
Severance Costs											2.4
Revenue, Net												$ 11.5
U.S. Pipe [Member]
Proceeds from Divestiture of Businesses	$ 94.0										$ 4.5
Noncash or Part Noncash Divestiture, Amount of Consideration Received										$ 10.1