Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Settlements	$ 2.6	$ 12.6	$ 2.6	$ 12.6
US [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	9.3	10.6	18.3	21.2
Interest cost	27.7	31.3	55.4	62.5
Expected return on plan assets	(50.5)	(50.5)	(101.0)	(101.0)
Prior service cost amortization	0.8	0.7	1.5	1.4
Actuarial loss amortization	21.5	19.6	42.6	39.4
Settlements	2.6	12.6	2.6	12.5
Curtailments	0.0	3.1	0.0	3.1
Special termination benefits	0.6	2.1	0.6	4.8
Other	0.0	0.0	0.0	1.1
Net periodic benefit cost	12.0	29.5	20.0	45.0
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6.1	7.9	12.3	16.1
Interest cost	11.1	14.2	22.7	29.2
Expected return on plan assets	(19.6)	(19.1)	(40.3)	(40.2)
Prior service cost amortization	(0.1)	0.1	(0.1)	0.1
Actuarial loss amortization	9.1	10.1	18.3	20.6
Settlements	0.0	0.0	0.0	(0.1)
Curtailments	0.0	0.0	0.0	0.0
Special termination benefits	0.0	0.9	0.0	0.9
Other	0.5	0.5	1.0	1.0
Net periodic benefit cost	7.1	14.6	13.9	27.6
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.6	0.7	1.1	1.4
Interest cost	0.5	0.5	1.0	1.1
Expected return on plan assets	0.0	0.0	0.0	0.0
Prior service cost amortization	0.0	0.0	0.0	0.0
Actuarial loss amortization	0.1	0.2	0.3	0.4
Other	0.0	0.0	0.0	0.0
Net periodic benefit cost	$ 1.2	$ 1.4	$ 2.4	$ 2.9