Document and Entity Information (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Mar. 31, 2013	Apr. 26, 2013	Mar. 31, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	Laclede Gas Company
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		12,847
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2013