Basis of Presentation and Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Reconciled Basic and Diluted EPS
Net income	$ 183.3	$ 150.1
Less: Allocation to participating securities	(0.4)	(0.3)
Net income available to common shareowners	$ 182.9	$ 149.8
Basic weighted average outstanding shares	141.8	141.8
Effect of dilutive securities
Stock options	1.7	2.3
Performance shares	0.4	0.4
Diluted weighted average outstanding shares	143.9	144.5
Earnings per share:
Basic	$ 1.29	$ 1.06
Diluted	$ 1.27	$ 1.04