Document and Entity Information	9 Months Ended
	Jun. 30, 2013	Aug. 05, 2013 Common Stock [Member]	Aug. 05, 2013 Class B Stock [Member]
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3
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