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Document And Entity Information - shares
 6 Months Ended
Mar. 31, 2018
May 02, 2018
Document And Entity Information [Abstract]    
Entity Registrant Name IES Holdings, Inc.  
Entity Central Index Key 0001048268  
Document Type 10-Q  
Document Period End Date Mar. 31, 2018  
Amendment Flag false  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --09-30  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   21,209,916
Entity Well-known Seasoned Issuer No  
Entity Current Reporting Status Yes  
Entity Voluntary Filers No  
TradingSymbol IESC