Document And Entity Information - shares	3 Months Ended
	Dec. 31, 2016	Jan. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	GRIFFON CORP
Document Type	10-Q
Current Fiscal Year End Date	--09-30
Entity Common Stock, Shares Outstanding		47,266,068
Amendment Flag	false
Entity Central Index Key	0000050725
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2017
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q1