Share-Based Compensation (Total Before-Tax Share-Based Compensation Cost by Type of Program) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Before-Tax Share-Based Compensation	$ 40.7	$ 37.6	$ 45.7
Deferred Stock Units
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Before-Tax Share-Based Compensation	34.5	29.9	28.8
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Before-Tax Share-Based Compensation	1.4	4.2	12.6
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Before-Tax Share-Based Compensation	$ 4.8	$ 3.5	$ 4.3