Disclosures About Derivative Instruments and Hedging Activities Textual (Details) (USD $) In Thousands, unless otherwise specified												3 Months Ended	9 Months Ended
	Jun. 30, 2013	Sep. 30, 2012	Jun. 30, 2012	Jun. 30, 2013 Electric Utility electric transmission congestion [Member] kWh	Jun. 30, 2012 Electric Utility electric transmission congestion [Member] kWh	Jun. 30, 2013 Gas Utility [Member] DTH	Jun. 30, 2012 Gas Utility [Member] DTH	Jun. 30, 2013 Electric Utility [Member] kWh	Jun. 30, 2012 Electric Utility [Member] kWh	Jun. 30, 2013 Interest Rate Protection Agreements [Member]	Jun. 30, 2012 Interest Rate Protection Agreements [Member]	Jun. 30, 2012 Interest Rate Swap [Member]	Jun. 30, 2012 Interest Rate Swap [Member]
Disclosures About Derivative Instruments Hedging Activities (Textual) [Abstract]
Notional amount (in units)				260,600,000	261,000,000	11,700,000	13,200,000	327,400,000	654,700,000
Total Derivatives Liability	$ 22,950		$ 42,473					$ (6,060)	$ (13,095)
Total Derivatives Assets	8,228		545
Underlying variable rate debt										173,000	173,000
Recorded loss amount included in Other Income, Net												0	(682)
Maximum length of time hedged in price risk cash flow hedges (in months)				11 months		16 months		11 months
Amount of net losses associated with interest rate hedges to be reclassified with interest rate hedges during the next 12 months	2,203
Restricted Cash in brokerage accounts	$ 2,636	$ 0	$ 1,604