MGE ACQUISITION (Details) (USD $)	3 Months Ended	6 Months Ended			0 Months Ended	6 Months Ended	0 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013	Sep. 01, 2013 Laclede Group [Member] Missouri Gas Energy (MGE) [Member]	Mar. 31, 2014 Laclede Group [Member] Missouri Gas Energy (MGE) [Member]	Dec. 20, 2013 Gas Utility [Member] Laclede Group [Member] Missouri Gas Energy (MGE) [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross					$ 975,000,000
Assets, Fair Value Adjustment						23,900,000
Proceeds from Divestiture of Businesses		23,925,000	0				11,000,000
Payments to Acquire Businesses, Net of Cash Acquired						940,100,000
Goodwill	216,370,000	216,370,000	0	247,078,000
Regulated Operating Revenue, Other	$ 236,600,000	$ 396,700,000