Retirement Benefits (Changes recognized in other comprehensive income on pretax basis) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
US [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss arising during the period	$ 230.0	$ 236.5
Amortization of net actuarial loss	(78.6)	(63.9)
Prior service cost arising during the period	1.8	0.6
Amortization of prior service cost	(2.7)	(2.6)
Total	150.5	170.6
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss arising during the period	128.6	(108.8)
Amortization of net actuarial loss	(18.8)	(31.9)
Prior service cost arising during the period	0	0
Amortization of prior service cost	(0.5)	(0.6)
Total	109.3	(141.3)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss arising during the period	10.2	(2.5)
Amortization of net actuarial loss	(2.9)	(3.8)
Amortization of prior service cost	0	0
Total	$ 7.3	$ (6.3)