Document and Entity Information - shares	3 Months Ended
	Apr. 30, 2019	Jun. 06, 2019
Document And Entity Information
Entity Registrant Name	ARGAN INC
Entity Central Index Key	0000100591
Document Type	10-Q
Document Period End Date	Apr. 30, 2019
Amendment Flag	false
Current Fiscal Year End Date	--01-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		15,633,302
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1