Document and Entity Information - shares	6 Months Ended
	Jul. 31, 2018	Aug. 31, 2018
Document And Entity Information
Entity Registrant Name	ARGAN INC
Entity Central Index Key	0000100591
Trading Symbol	AGX
Document Type	10-Q
Document Period End Date	Jul. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--01-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		15,568,719
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2