Other Income Net (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Other Income Net
Interest and interest-related income	$ 2.4	$ 2.3	$ 2.9
Antargaz Competition Authority matter	0	9.4	0
Utility non-tariff service income	2.7	6.4	2.4
Foreign currency hedge gain (loss)	0.5	(6.1)	0
Gain on sale of Atlantic Energy, LLC	0	0	36.5
Finance charges	18.8	15.1	11.3
Partnership interest rate protection agreement loss	0	0	(12.2)
Other, net	13.9	19.4	17.1
Total other income, net	$ 38.3	$ 46.5	$ 58.0