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Document And Entity Information - USD ($)
 12 Months Ended
Jan. 31, 2017
Mar. 24, 2017
Jul. 31, 2016
Document and Entity Information [Abstract]      
Entity Registrant Name REX AMERICAN RESOURCES Corp    
Document Type 10-K    
Current Fiscal Year End Date --01-31    
Entity Common Stock, Shares Outstanding   6,558,679  
Entity Public Float     $ 368,483,290
Amendment Flag false    
Entity Central Index Key 0000744187    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Filer Category Accelerated Filer    
Entity Well-known Seasoned Issuer No    
Document Period End Date Jan. 31, 2017    
Document Fiscal Year Focus 2016    
Document Fiscal Period Focus FY