Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
US [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 9.0	$ 10.6
Interest cost	27.7	31.2
Expected return on plan assets	(50.5)	(50.5)
Actuarial loss amortization	21.1	19.8
Prior service cost amortization	0.7	0.7
Settlements	0.0	(0.1)
Special termination benefits	0.0	2.7
Other	0.0	1.1
Net periodic benefit cost	8.0	15.5
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6.2	8.2
Interest cost	11.6	15.0
Expected return on plan assets	(20.7)	(21.1)
Actuarial loss amortization	9.2	10.5
Prior service cost amortization	0.0	0.0
Settlements	0.0	(0.1)
Special termination benefits	0.0	0.0
Other	0.5	0.5
Net periodic benefit cost	6.8	13.0
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.5	0.7
Interest cost	0.5	0.6
Expected return on plan assets	0.0	0.0
Actuarial loss amortization	0.2	0.2
Prior service cost amortization	0.0	0.0
Settlements	0.0	0.0
Special termination benefits	0.0	0.0
Other	0.0	0.0
Net periodic benefit cost	$ 1.2	$ 1.5