Retirement Benefits (Details 2) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit)	$ 4.9	$ 3.0
Net actuarial loss	1,235.1	1,099.9
Total	1,240.0	1,102.9
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit)	(15.9)	(22.9)
Net actuarial loss	15.7	17.1
Total	$ (0.2)	$ (5.8)