Retirement Benefits (Summary of changes in pension plan assets fair value classified as level 3) (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	$ 210.5	$ 187.2
Actual return on plan assets:
Assets held at end of year	16.5	25.0
Assets sold during the period	1.2	0.2
Purchases, sales, and settlements, net	(9.0)	(1.9)
Fair Value at End of Year	219.2	210.5
Pooled Funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	9.4	8.7
Actual return on plan assets:
Assets held at end of year	(0.9)	1.6
Assets sold during the period	1.2	0.2
Purchases, sales, and settlements, net	(0.4)	(1.1)
Fair Value at End of Year	9.3	9.4
Real Estate [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	132.8	115.0
Actual return on plan assets:
Assets held at end of year	17.4	17.8
Assets sold during the period	0	0
Purchases, sales, and settlements, net	0	0
Fair Value at End of Year	150.2	132.8
Insurance Contracts [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value at beginning of year	68.3	63.5
Actual return on plan assets:
Assets held at end of year	0	5.6
Assets sold during the period	0	0
Purchases, sales, and settlements, net	(8.6)	(0.8)
Fair Value at End of Year	$ 59.7	$ 68.3