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Employee Benefit Plans (Details)
$ in Thousands
 12 Months Ended
Sep. 30, 2017
USD ($)
years
Sep. 30, 2016
USD ($)
Sep. 30, 2015
USD ($)
Executive Saving Plan [Abstract]      
Maximum percentage of salary permitted for deferral 75.00%    
Post Retirement Benefit Plan [Abstract]      
Defined Benefit Plan, Percentage Vest After Ten Years Of Service 50.00%    
Denfied Benefits Plan, Annual Percentage Vested 10.00%    
Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Benefit Obligation $ 815 $ 875  
Expense Related to Post Retirement Benefit Plan $ 0 $ 65 $ 11
Multiemployer Plans [Abstract]      
Percentage of Plan Funded   82.82%  
IES 401(k) Plan [Member]      
Defined Contribution Plan Disclosure [Line Items]      
Defined Benefit Plan Plans Fully Vested Number Of Years | years 3    
Defined Benefit Plan Minimum Age | years 21    
Minimum Employment Term For Eligibility 60 days    
401(k) Matching Expense $ 1,157 $ 737 $ 387