Document and Entity Information - shares	3 Months Ended
	Apr. 30, 2025	May 30, 2025
Document And Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Apr. 30, 2025
Document Transition Report	false
Entity File Number	001-31756
Entity Registrant Name	ARGAN INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-1947195
Entity Address, Address Line One	4075 Wilson Boulevard, Suite 440
Entity Address, City or Town	Arlington
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	22203
City Area Code	301
Local Phone Number	315-0027
Title of 12(b) Security	Common Stock, $0.15 par value
Trading Symbol	AGX
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		13,640,813
Entity Central Index Key	0000100591
Current Fiscal Year End Date	--01-31
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q1
Amendment Flag	false