Basis of Presentation and Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Reconciled Basic and Diluted EPS
Net income	$ 180.3	$ 175.9	$ 378.4	$ 337.3
Less: Allocation to participating securities	(0.2)	(0.3)	(0.5)	(0.5)
Net income available to common shareowners	$ 180.1	$ 175.6	$ 377.9	$ 336.8
Basic weighted average outstanding shares	138.5	140.0	138.5	139.6
Effect of dilutive securities
Stock options	1.5	1.6	1.5	1.6
Performance shares	0.2	0.2	0.2	0.2
Diluted weighted average outstanding shares	140.2	141.8	140.2	141.4
Earnings Per Share, Basic [Abstract]
Basic	$ 1.30	$ 1.25	$ 2.73	$ 2.41
Earnings Per Share, Diluted [Abstract]
Diluted	$ 1.28	$ 1.24	$ 2.70	$ 2.38