Basis of Presentation and Accounting Policies (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Reconciled Basic and Diluted EPS
Net income	$ 214.7	$ 185.5
Less: Allocation to participating securities	(0.2)	(0.2)
Net income available to common shareowners	$ 214.5	$ 185.3
Basic weighted average outstanding shares	128.3	131.8
Effect of dilutive securities
Stock options	1.2	0.8
Performance shares	0.2	0.0
Diluted weighted average outstanding shares	129.7	132.6
Basic earnings per share:
Basic	$ 1.67	$ 1.41
Diluted earnings per share:
Diluted	$ 1.65	$ 1.40