Employee Benefit Plans	12 Months Ended
Sep. 30, 2017
Employee Benefit Plans [Abstract]
401(k) Plan	13. EMPLOYEE BENEFIT PLANS 401(k) Plan In November 1998, we established the IES Holdings, Inc. 401(k) Retirement Savings Plan. All full-time IES employees are eligible to participate on the first day of the month subsequent to completing sixty days of service and attaining age twenty-one. Participants become vested in our matching contributions following three years of service. We also maintain several subsidiary retirement savings plans. We recognized $1,157, $737, and $387 in matching expenses in fiscal years 2017, 2016 and 2015, respectively. Executive Savings Plan Under the Executive Deferred Compensation Plan adopted on July 1, 2004 (the “Executive Savings Plan”), certain employees are permitted to defer a portion (up to 75%) of their base salary and/or bonus for a plan year. The Human Resources and Compensation Committee of the Board of Directors may, in its sole discretion, credit one or more participants with an employer deferral (contribution) in such amount as the Committee may choose (“Employer Contribution”). The Employer Contribution, if any, may be a fixed dollar amount, a fixed percentage of the participant’s compensation, base salary, or bonus, or a “matching” amount with respect to all or part of the participant’s elective deferrals for such plan year, and/or any combination of the foregoing as the Committee may choose. No compensation earned during the years ended September 30, 2017, 2016 or 2015 was deferred under this plan. Post Retirement Benefit Plans Certain individuals at one of the Company’s locations are entitled to receive fixed annual payments that reach a maximum amount, as specified in the related agreements, for a ten year period following retirement or, in some cases, the attainment of 62 years of age. We recognize the unfunded status of the plan as a non-current liability in our Consolidated Balance Sheet. Benefits vest 50% after ten years of service, which increases by 10% per annum until benefits are fully vested after 15 years of service. We had an unfunded benefit liability of $815 and $875 recorded as of September 30, 2017 and 2016, respectively. We recognized compensation expense related to these agreements of zero, $65, and $11 during the years ended September 30, 2017, 2016 and 2015, respectively. Multiemployer Pension Plan Infrastructure Solutions participates in a multiemployer direct benefit pension plan for employees covered under our collective bargaining agreement. We do not administer the plan. We do not significantly participate in this plan. As of December 31, 2016, this plan was funded at 82.82%.

Employee Benefit Plans

12 Months Ended

Sep. 30, 2017

13. EMPLOYEE BENEFIT PLANS

401(k) Plan

In November 1998, we established the IES Holdings, Inc. 401(k) Retirement Savings Plan. All full-time IES employees are eligible to participate on the first day of the month subsequent to completing sixty days of service and attaining age twenty-one. Participants become vested in our matching contributions following three years of service. We also maintain several subsidiary retirement savings plans. We recognized $1,157, $737, and $387 in matching expenses in fiscal years 2017, 2016 and 2015, respectively.

Executive Savings Plan

Under the Executive Deferred Compensation Plan adopted on July 1, 2004 (the “Executive Savings Plan”), certain employees are permitted to defer a portion (up to 75%) of their base salary and/or bonus for a plan year. The Human Resources and Compensation Committee of the Board of Directors may, in its sole discretion, credit one or more participants with an employer deferral (contribution) in such amount as the Committee may choose (“Employer Contribution”). The Employer Contribution, if any, may be a fixed dollar amount, a fixed percentage of the participant’s compensation, base salary, or bonus, or a “matching” amount with respect to all or part of the participant’s elective deferrals for such plan year, and/or any combination of the foregoing as the Committee may choose. No compensation earned during the years ended September 30, 2017, 2016 or 2015 was deferred under this plan.

Post Retirement Benefit Plans

Certain individuals at one of the Company’s locations are entitled to receive fixed annual payments that reach a maximum amount, as specified in the related agreements, for a ten year period following retirement or, in some cases, the attainment of 62 years of age. We recognize the unfunded status of the plan as a non-current liability in our Consolidated Balance Sheet. Benefits vest 50% after ten years of service, which increases by 10% per annum until benefits are fully vested after 15 years of service. We had an unfunded benefit liability of $815 and $875 recorded as of September 30, 2017 and 2016, respectively. We recognized compensation expense related to these agreements of zero, $65, and $11 during the years ended September 30, 2017, 2016 and 2015, respectively.

Multiemployer Pension Plan

Infrastructure Solutions participates in a multiemployer direct benefit pension plan for employees covered under our collective bargaining agreement. We do not administer the plan. We do not significantly participate in this plan. As of December 31, 2016, this plan was funded at 82.82%.