Retirement Benefits (Amounts recognized in balance sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	$ 4.3	$ 22.9
Accrued liabilities	(26.1)	(48.4)
US [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	4.0	22.7
Accrued liabilities	(15.7)	(37.7)
Noncurrent liabilities	(514.6)	(241.7)
Net Amount Recognized	(526.3)	(256.7)
International [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	0.3	0.2
Accrued liabilities	0.0	0.0
Noncurrent liabilities	(345.4)	(367.5)
Net Amount Recognized	(345.1)	(367.3)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued liabilities	(10.4)	(10.7)
Noncurrent liabilities	$ (76.5)	$ (82.8)