Disclosures About Derivative Instruments and Hedging Activities (Details Textual) In Millions, unless otherwise specified				9 Months Ended				9 Months Ended
	Jun. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 Foreign Currency [Member] USD ($)	Jun. 30, 2012 Foreign Currency [Member] USD ($)	Jun. 30, 2013 Interest Rate Swaps [Member] EUR (€)	Jun. 30, 2012 Interest Rate Swaps [Member] EUR (€)	Jun. 30, 2012 Interest Rate Protection Agreements [Member] USD ($)	Jun. 30, 2013 Interest Rate Protection Agreements [Member] USD ($)	Jun. 30, 2012 Net Investment Hedges [Member] EUR (€)	Jun. 30, 2013 LPG (millions of gallons) [Member]	Jun. 30, 2013 Natural Gas (millions of dekatherms) [Member]	Jun. 30, 2013 Electricity (millions of kilowatt-hours) [Member] Forward Purchase Contracts [Member]	Jun. 30, 2013 Electricity (millions of kilowatt-hours) [Member] Forward Sales Contracts [Member]	Jun. 30, 2013 Electric transmission congestion - Electric Utility [Member] kWh	Jun. 30, 2012 Electric transmission congestion - Electric Utility [Member] kWh	Jun. 30, 2013 Gas Utility [Member] DTH	Jun. 30, 2012 Gas Utility [Member] DTH	Jun. 30, 2013 Midstream & Marketing [Member] Electric transmission congestion (excluding Electric Utility) [Member] kWh	Jun. 30, 2012 Midstream & Marketing [Member] Electric transmission congestion (excluding Electric Utility) [Member] kWh	Jun. 30, 2013 Electric Utility - Forward Contract [Member] USD ($) kWh	Jun. 30, 2012 Electric Utility - Forward Contract [Member] USD ($) kWh	Jun. 30, 2013 Midstream and Marketing Natural Gas [Member] DTH	Jun. 30, 2012 Midstream and Marketing Natural Gas [Member] DTH	Jun. 30, 2013 Midstream and Marketing Propane Storage [Member] gal	Jun. 30, 2012 Midstream and Marketing Propane Storage [Member] gal
Disclosures About Derivative Instruments Hedging Activities (Textual) [Abstract]
Notional amount (in units)															260,600,000	261,000,000	11,700,000	13,200,000	1,609,200,000	1,285,500,000	327,400,000	654,700,000	2,700,000	4,100,000	1,800,000	2,200,000
Maximum length of time hedged in price risk cash flow hedges (in months)				33 months							19 months	41 months	27 months	14 months			16 months		11 months		11 months
Derivative Liability, Fair Value, Gross Liability	$ 80.7		$ 187.0																		$ 6.1	$ 13.1
Notional amount				170.3	75.0	440.5	441.9	173.0	173.0	14.5
Weighted Average Length if Time Hedged (in months)				14 months							7 months	10 months	9 months	3 months
Recorded loss amount included in Other Income, Net								0.7
Minimum approximate range of estimated dollar-denominated purchases of LPG (as a percent)				15.00%
Maximum approximate range of estimated dollar-denominated purchases of LPG (as a percent)				30.00%
Disclosures About Derivative Instruments Hedging Activities (Additional Textual) [Abstract]
Net losses associated with commodity price risk hedges expected to be reclassified into earnings during the next twelve months	15.6
Amount of net losses associated with interest rate hedges to be reclassified with interest rate hedges during the next 12 months	2.2
Amount of net gains associated with currency rate risk to be reclassified into earnings during the next 12 months	1.0
Restricted Cash in brokerage accounts	$ 6.0	$ 3.0	$ 7.6