Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2015	Dec. 02, 2015	Mar. 31, 2015
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Trading Symbol	GENC
Entity Registrant Name	GENCOR INDUSTRIES INC
Entity Central Index Key	0000064472
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Public Float			$ 67,254,700
Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		8,028,882
Class B Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,509,238