Document and Entity Information (USD $)	12 Months Ended
	Sep. 30, 2014	Nov. 21, 2014	Mar. 31, 2014
Entity Information [Line Items]
Entity Registrant Name	LACLEDE GROUP INC
Entity Central Index Key	0001126956
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,452,654,866
Entity Common Stock, Shares Outstanding		43,212,824
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 30, 2014
Subsidiaries
Entity Information [Line Items]
Entity Registrant Name	LACLEDE GAS CO
Entity Central Index Key	0000057183
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		24,577
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 30, 2014