Document and Entity Information (USD $)	12 Months Ended
	Sep. 30, 2012	Mar. 31, 2012	Dec. 03, 2012 Common Stock	Dec. 03, 2012 Class B Stock
Entity Registrant Name	GENCOR INDUSTRIES INC
Entity Central Index Key	0000064472
Document Type	10-K
Document Period End Date	Sep. 30, 2012
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--09-30
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding			8,008,632	1,509,238
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Public Float		$ 46,932,200
Entity Voluntary Filers	No