Document And Entity Information (USD $)	12 Months Ended
	Sep. 30, 2011	Mar. 31, 2011	Dec. 12, 2011 Common Stock [Member]	Dec. 12, 2011 Class B Stock [Member]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 30, 2011
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2011
Entity Registrant Name	GENCOR INDUSTRIES INC
Entity Central Index Key	0000064472
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 Public Float		$ 52,429,972
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No