Other Income (Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Components of other expense
Net (loss) gain on dispositions of securities and property	$ (0.5)	$ (1.0)	$ 0.9
Interest income	9.8	7.8	6.0
Royalty income	3.3	2.3	3.6
Environmental charges	(13.5)	(9.3)	(4.5)
Other	6.6	(4.8)	(8.1)
Other income (expense)	$ 5.7	$ (5.0)	$ (2.1)