Retirement Benefits (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Settlements	$ 4.1	$ 2.0	$ 4.1	$ 2.0
US [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6.9	9.3	15.2	18.3
Interest cost	27.6	27.7	52.5	55.4
Expected return on plan assets	(51.7)	(50.5)	(104.4)	(101.0)
Prior service cost amortization	0.6	0.8	1.2	1.5
Actuarial loss amortization	20.9	21.5	47.0	42.6
Settlements	4.1	2.6	4.1	2.6
Curtailment	0.1	0.0	4.3	0.0
Special termination benefits	(0.1)	0.6	1.0	0.6
Other	0.0	0.0	0.0	0.0
Net periodic benefit cost	8.4	12.0	20.9	20.0
US [Member] | Discontinued Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	0.1	2.1	0.7	3.9
US [Member] | Continuing Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	8.3	9.9	20.2	16.1
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	6.3	6.1	13.0	12.3
Interest cost	7.9	11.1	15.5	22.7
Expected return on plan assets	(18.3)	(19.6)	(36.8)	(40.3)
Prior service cost amortization	(0.1)	(0.1)	(0.1)	(0.1)
Actuarial loss amortization	13.2	9.1	27.1	18.3
Settlements	4.0	0.0	1.7	0.0
Curtailment	1.8	0.0	(1.3)	0.0
Special termination benefits	0.1	0.0	0.5	0.0
Other	(2.2)	0.5	0.5	1.0
Net periodic benefit cost	12.7	7.1	20.1	13.9
International [Member] | Discontinued Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	3.4	0.2	4.1	1.6
International [Member] | Continuing Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	9.3	6.9	16.0	12.3
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.2	0.6	0.7	1.1
Interest cost	0.4	0.5	0.8	1.0
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	0.0	0.1	0.2	0.3
Settlements	0.0	0.0	0.0	0.0
Curtailment	0.0	0.0	0.0	0.0
Special termination benefits	0.0	0.0	0.0	0.0
Other	0.0	0.0	0.0	0.0
Net periodic benefit cost	0.6	1.2	1.7	2.4
Other Postretirement Benefit Plan [Member] | Discontinued Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	0.0	0.0	0.0	0.0
Other Postretirement Benefit Plan [Member] | Continuing Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 0.6	$ 1.2	$ 1.7	$ 2.4