Commitments and Contingent Liabilities (Details 2) - USD ($) $ in Millions	Sep. 30, 2015	Sep. 30, 2014
Accrual for Environmental Loss Contingencies [Abstract]
Other current liabilities	$ 13.4
Other liabilities	48.0
Total recorded environmental remediation costs	61.4	$ 60.0
Receivables	(1.6)
Other assets	(6.6)
Total recorded probable expected recoveries	(8.2)
Net environmental remediation costs	53.2
Discounted ongoing operating maintenance expenditures	39.3
Asset Retirement Obligation [Abstract]
Other current liabilities	0.4	0.3
Other liabilities	19.8	21.9
Total recorded conditional asset retirement obligations	20.2	22.2
Probable expected recoveries recorded in other assets	(0.3)	(0.3)
Net conditional asset retirement obligations	$ 19.9	$ 21.9