Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
US [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10.6	$ 13.0	$ 21.3	$ 26.0
Interest cost	32.7	29.2	65.4	58.4
Expected return on plan assets	(46.9)	(47.7)	(93.9)	(92.6)
Prior service cost amortization	0.7	0.7	1.4	1.4
Actuarial loss amortization	19.6	29.1	39.2	58.2
Settlements	0	0	0	0
Special termination benefits	0	0	0.2	0
Other	0	0	0	0
Net periodic benefit cost	16.7	24.3	33.6	51.4
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	9.0	8.0	17.8	16.3
Interest cost	16.9	14.3	33.5	29.0
Expected return on plan assets	(19.6)	(17.6)	(38.8)	(35.9)
Prior service cost amortization	0	0.1	0.1	0.2
Actuarial loss amortization	8.9	6.6	17.7	13.4
Settlements	0.5	0	0.5	0
Special termination benefits	0	0	0	0
Other	0.5	0.5	1.0	1.1
Net periodic benefit cost	16.2	11.9	31.8	24.1
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.8	1.1	1.6	2.1
Interest cost	0.6	0.5	1.2	1.0
Expected return on plan assets	0	0	0	0
Prior service cost amortization	0	0	0	0
Actuarial loss amortization	0.5	0.6	0.9	1.2
Special termination benefits	0	0	0	0
Other	0	0	0	0
Net periodic benefit cost	$ 1.9	$ 2.2	$ 3.7	$ 4.3