Commitments and Contingent Liabilities (Details 1) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Accrual for Environmental Loss Contingencies [Abstract]
Other current liabilities	$ 10.7
Other liabilities	56.9
Total recorded environmental remediation costs	67.6	$ 73.9
Receivables	(1.2)
Other assets	(10.1)
Total recorded probable expected recoveries	(11.3)
Net environmental remediation costs	56.3
Discounted ongoing operating maintenance expenditures	47.5
Asset Retirement Obligation [Abstract]
Other current liabilities	0.7	0.7
Other liabilities	20.5	19.9
Total recorded conditional asset retirement obligations	21.2	20.6
Receivables	(0.1)	(0.1)
Other assets	(0.2)	(0.2)
Total recorded probable expected recoveries	(0.3)	(0.3)
Net conditional asset retirement obligations	$ 20.9	$ 20.3