Disclosures About Derivative Instruments and Hedging Activities (Details Textual) In Millions, unless otherwise specified				3 Months Ended
	Dec. 31, 2013 USD ($)	Sep. 30, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2013 Foreign Currency [Member] USD ($)	Dec. 31, 2012 Foreign Currency [Member] USD ($)	Dec. 31, 2013 Interest Rate Swaps [Member] EUR (€)	Dec. 31, 2012 Interest Rate Swaps [Member] EUR (€)	Dec. 31, 2013 Interest Rate Protection Agreements [Member] USD ($)	Dec. 31, 2012 Interest Rate Protection Agreements [Member] USD ($)	Dec. 31, 2013 Cross Currency Interest Rate Contract [Member] USD ($)	Dec. 31, 2013 LPG (millions of gallons) [Member]	Dec. 31, 2013 Electricity (millions of kilowatt-hours) [Member] Forward Purchase Contracts [Member] kWh	Dec. 31, 2012 Electricity (millions of kilowatt-hours) [Member] Forward Purchase Contracts [Member] kWh	Dec. 31, 2013 Electricity (millions of kilowatt-hours) [Member] Forward Sales Contracts [Member] kWh	Dec. 31, 2012 Electricity (millions of kilowatt-hours) [Member] Forward Sales Contracts [Member] kWh	Dec. 31, 2013 Electric transmission congestion - Electric Utility [Member] kWh	Dec. 31, 2012 Electric transmission congestion - Electric Utility [Member] kWh	Dec. 31, 2013 Brokerage Accounts [Member] USD ($)	Dec. 31, 2012 Brokerage Accounts [Member] USD ($)	Dec. 31, 2013 Gas Utility [Member] DTH	Dec. 31, 2012 Gas Utility [Member] DTH	Dec. 31, 2013 Midstream & Marketing [Member] Natural Gas (millions of dekatherms) [Member] DTH	Dec. 31, 2012 Midstream & Marketing [Member] Natural Gas (millions of dekatherms) [Member] DTH	Dec. 31, 2013 Midstream & Marketing [Member] Electric transmission congestion (excluding Electric Utility) [Member] kWh	Dec. 31, 2012 Midstream & Marketing [Member] Electric transmission congestion (excluding Electric Utility) [Member] kWh	Dec. 31, 2013 Electric Utility - Forward Contract [Member] USD ($) kWh	Dec. 31, 2012 Electric Utility - Forward Contract [Member] USD ($) kWh	Dec. 31, 2013 Midstream and Marketing Natural Gas [Member] DTH	Dec. 31, 2012 Midstream and Marketing Natural Gas [Member] DTH	Dec. 31, 2013 Midstream and Marketing Propane Storage [Member] gal	Dec. 31, 2012 Midstream and Marketing Propane Storage [Member] gal	Dec. 31, 2013 Designated as Hedging Instrument [Member] LPG (millions of gallons) [Member] gal	Dec. 31, 2012 Designated as Hedging Instrument [Member] LPG (millions of gallons) [Member] gal
Disclosures About Derivative Instruments Hedging Activities (Textual) [Abstract]
Notional amount (in units)												664,700,000	1,180,800,000	371,000,000	195,300,000	117,900,000	118,200,000			9,700,000	13,000,000	27,400,000	21,100,000	968,000,000	677,500,000	324,400,000	482,300,000	1,100,000	2,400,000	2,200,000	2,000,000	215,200,000	212,100,000
Maximum length of time hedged in price risk cash flow hedges (in months)				27 months							21 months									9 months						11 months
Derivative Liability, Fair Value, Gross Liability	$ 49.2	$ 57.5	$ 128.8																							$ 3.2	$ 8.2
Notional amount				149.1	120.0	439.8	441.2	0	173.0	52.0
Weighted Average Length if Time Hedged (in months)				12 months							5 months
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	43.6
Amount of net losses associated with interest rate hedges to be reclassified with interest rate hedges during the next 12 months	2.7
Amount of net gains associated with currency rate risk to be reclassified into earnings during the next 12 months	3.4
Restricted cash	$ 4.5	$ 8.3	$ 6.9															$ 3.2	$ 6.9