Derivative Instruments and Hedging Activities (Details) In Millions, unless otherwise specified	0 Months Ended		12 Months Ended					12 Months Ended		12 Months Ended							12 Months Ended			12 Months Ended		12 Months Ended				12 Months Ended		12 Months Ended						12 Months Ended
	Sep. 30, 2014 gal	Sep. 30, 2013 gal	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)		Sep. 30, 2014 Interest Rate Swaps [Member] EUR (€)	Sep. 30, 2013 Interest Rate Swaps [Member] EUR (€)	Sep. 30, 2014 Foreign Currency [Member] USD ($)	Sep. 30, 2013 Foreign Currency [Member] USD ($)	Sep. 30, 2012 Interest Rate Protection Agreements [Member] USD ($)	Sep. 30, 2014 Interest Rate Protection Agreements [Member] USD ($)	Sep. 30, 2013 Interest Rate Protection Agreements [Member] USD ($)	Sep. 30, 2014 Net Investment Hedges EUR (€)	Sep. 30, 2013 Net Investment Hedges EUR (€)	Sep. 30, 2014 Electric transmission congestion - Electric Utility [Member] kWh	Sep. 30, 2013 Electric transmission congestion - Electric Utility [Member] kWh	Sep. 30, 2014 LPG [Member]	Sep. 30, 2014 Natural Gas [Member] DTH	Sep. 30, 2013 Natural Gas [Member] DTH	Sep. 30, 2014 Electricity (millions of kilowatt-hours) [Member] Call Option [Member] kWh	Sep. 30, 2013 Electricity (millions of kilowatt-hours) [Member] Call Option [Member] kWh	Sep. 30, 2014 Electricity (millions of kilowatt-hours) [Member] Put Option [Member] kWh	Sep. 30, 2013 Electricity (millions of kilowatt-hours) [Member] Put Option [Member] kWh	Sep. 30, 2014 Brokerage Accounts [Member] USD ($)	Sep. 30, 2013 Brokerage Accounts [Member] USD ($)	Sep. 30, 2014 Gas Utility DTH	Sep. 30, 2013 Gas Utility DTH	Sep. 30, 2014 Electric Utility - Forward Contract [Member] kWh	Sep. 30, 2013 Electric Utility - Forward Contract [Member] kWh	Sep. 30, 2014 Midstream And Marketing Natural Gas [Member] DTH	Sep. 30, 2013 Midstream And Marketing Natural Gas [Member] DTH	Sep. 30, 2014 Midstream And Marketing Propane Storage [Member] gal	Sep. 30, 2013 Midstream And Marketing Propane Storage [Member] gal	Sep. 30, 2014 Minimum Foreign Currency [Member]	Sep. 30, 2014 Maximum Foreign Currency [Member]	Sep. 30, 2014 Flaga Term Loan, due September 2016 [Member] Flaga [Member] Notes Payable to Banks USD ($)	Sep. 30, 2013 Flaga Term Loan, due September 2016 [Member] Flaga [Member] Notes Payable to Banks USD ($)	Sep. 30, 2013 Flaga Term Loan, due September 2016 [Member] Flaga [Member] Notes Payable to Banks Cross Currency Contracts USD ($)
Derivative
Derivative, Nonmonetary Notional Amount, Volume	344,500,000	279,000,000
Maximum Length of Time Hedged in Price Risk Cash Flow Hedge			21 months
Notional amount (in units)															232,100,000	189,300,000		113,700,000	24,300,000	394,400,000	754,400,000	206,600,000	393,000,000			16,900,000	15,000,000	237,000,000	245,800,000	3,900,000	2,900,000	1,300,000	2,800,000
Maximum length of time hedged in price risk cash flow hedges								27 months									41 months			24 months		12 months				12 months		8 months
Fair values of electric utility's forward purchase power agreements			$ (75.2)	$ (57.5)	[1]
Net losses associated with commodity price risk hedges expected to be reclassified into earnings during the next twelve months			(2.3)
Underlying variable rate debt						401.1	440.5	219.8	200.2		0	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			4.6
Long-term Debt			3,510.8	3,609.4																																52.0	52.0	52.0
Restricted Cash in brokerage accounts			$ 16.6	$ 8.3																				$ 16.6	$ 7.0

[1] Certain immaterial amounts have been revised to correct the classification of derivatives.