EARNINGS (LOSS) PER SHARE ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC. - Antidilutive Shares (Details) - shares	3 Months Ended	6 Months Ended
Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2018
EARNINGS (LOSS) PER SHARE ATTRIBUTABLE TO THE STOCKHOLDERS OF ARGAN, INC.
Antidilutive stock options	530,000	486,500	486,500

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration