Disclosures About Derivative Instruments and Hedging Activities (Details Textual) In Millions, unless otherwise specified	1 Months Ended					12 Months Ended		12 Months Ended
	Aug. 31, 2011 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2013 Interest Rate Swaps [Member] EUR (€)	Sep. 30, 2012 Interest Rate Swaps [Member] EUR (€)	Sep. 30, 2013 Foreign Currency [Member] USD ($)	Sep. 30, 2012 Foreign Currency [Member] USD ($)	Sep. 30, 2012 Interest Rate Protection Agreements [Member] USD ($)	Sep. 30, 2013 Interest Rate Protection Agreements [Member] USD ($)	Sep. 30, 2013 Cross Currency Interest Rate Contract [Member] USD ($)	Sep. 30, 2013 Net Investment Hedges [Member] EUR (€)	Sep. 30, 2012 Net Investment Hedges [Member] EUR (€)	Sep. 30, 2013 Electric transmission congestion - Electric Utility [Member] kWh	Sep. 30, 2012 Electric transmission congestion - Electric Utility [Member] kWh	Sep. 30, 2013 Electric transmission congestion (excluding Electric Utility) [Member] kWh	Sep. 30, 2012 Electric transmission congestion (excluding Electric Utility) [Member] kWh	Sep. 30, 2013 LPG [Member]	Sep. 30, 2013 Natural Gas [Member] DTH	Sep. 30, 2012 Natural Gas [Member] DTH	Sep. 30, 2013 Electricity (millions of kilowatt-hours) [Member] Call Option [Member] kWh	Sep. 30, 2012 Electricity (millions of kilowatt-hours) [Member] Call Option [Member] kWh	Sep. 30, 2013 Electricity (millions of kilowatt-hours) [Member] Put Option [Member] kWh	Sep. 30, 2012 Electricity (millions of kilowatt-hours) [Member] Put Option [Member] kWh	Sep. 30, 2013 Brokerage Accounts [Member] USD ($)	Sep. 30, 2013 Gas Utility [Member] DTH	Sep. 30, 2012 Gas Utility [Member] DTH	Sep. 30, 2013 Electric Utility - Forward Contract [Member] USD ($) kWh	Sep. 30, 2012 Electric Utility - Forward Contract [Member] USD ($) kWh	Sep. 30, 2013 Midstream And Marketing Natural Gas [Member] DTH	Sep. 30, 2012 Midstream And Marketing Natural Gas [Member] DTH	Sep. 30, 2013 Midstream And Marketing Propane Storage [Member] gal	Sep. 30, 2012 Midstream And Marketing Propane Storage [Member] gal	Sep. 30, 2013 Senior Notes [Member]
Derivative [Line Items]
Notional amount (in units)													189,300,000	189,700,000	1,401,900,000	988,800,000		24,300,000	23,600,000	754,400,000	1,415,700,000	393,000,000	135,300,000		15,000,000	19,200,000	245,800,000	570,400,000	2,900,000	4,300,000	2,800,000	3,100,000
Maximum length of time hedged in price risk cash flow hedges						30 months											24 months			24 months					12 months		8 months
Fair values of electric utility's forward purchase power agreements		$ 55.4	$ 132.9																								$ 4.8	$ 9.2
Maximum period of hedging exposure to variability in cash flows associated with price risk, weighted average						11 months											6 months			8 months
Net losses associated with commodity price risk hedges expected to be reclassified into earnings during the next twelve months		(13.6)
Underlying variable rate debt				440.5	441.9	200.2	174.5	173.0	0	52.0	0	0
Recorded loss amount included in Other Income, Net								0.7
Amount of net losses associated with interest rate hedges to be reclassified with interest rate hedges during the next 12 months		(2.7)
Minimum approximate range of estimated dollar-denominated purchases of LPG						15.00%
Maximum approximate range of estimated dollar-denominated purchases of LPG						30.00%
Amount of net losses associated with currency rate risk to be reclassified into earnings during the next 12 months		2.5
Restricted Cash in brokerage accounts		8.3	3.0																					7.0
Write off of settled but unamortized interest rate protection agreements included in extinguishment of debt	$ 2.6
Interest rate stated percentage																																	7.125%