XML 13 R1.htm IDEA: XBRL DOCUMENT v3.5.0.2
Document and Entity Information - shares
 6 Months Ended
Jul. 31, 2016
Sep. 01, 2016
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, 2016  
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   15,032,469
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q2