Per Share Information EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share Reconciliation [Abstract]
Net income (loss) attributable to common shareholders of IES Holdings, Inc.	$ 2,250	$ 532	$ (27,304)	$ 4,373
Net income attributable to restricted shareholders of IES Holdings, Inc.	15	4		35
Net Income (loss)	$ 2,221	$ 536	$ (27,348)	$ 4,408
Weighted Average Number of Shares Outstanding, Basic	21,182,268	21,299,098	21,189,641,000	21,292,523
Effect of dilutive stock options and non-vested restricted stock	258,302	275,057		268,155
Weighted Average Number of Shares Outstanding, Diluted	21,440,570	21,574,155	21,189,641,000	21,560,678
Earnings (loss) per share attributable to IES Holdings, Inc.:
Earnings (loss) Per Share, Basic	$ 0.11	$ 0.02	$ (1.29)	$ 0.21
Earnings (loss) Per Share, Diluted	$ 0.11	$ 0.02	$ (1.29)	$ 0.2
Minority Interest Change in Redemption Value	$ (44)		$ (44)