Retirement Benefits (Details 2) (USD $) In Millions	Sep. 30, 2011	Sep. 30, 2010
Amounts included in accumulated other comprehensive loss, net of tax
Total	$ 1,033.6	$ 854.9
Pension Benefits [Member]
Amounts included in accumulated other comprehensive loss, net of tax
Prior service credit	(2.1)	(3.3)
Net actuarial loss	1,038.0	834.4
Net transition (benefit) obligation	(0.1)	0.2
Total	1,035.8	831.3
Other Postretirement Benefits [Member]
Amounts included in accumulated other comprehensive loss, net of tax
Prior service credit	(28.4)	(35.0)
Net actuarial loss	26.2	58.6
Net transition (benefit) obligation	0	0
Total	$ (2.2)	$ 23.6