Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Revenues	$ 695,993	$ 573,857	$ 512,395
Cost of services	569,013	473,966	429,269
Gross profit	126,980	99,891	83,126
Selling, general and administrative expenses	100,558	81,416	75,571
Contingent Consideration Expense	652	0	0
(Gain) loss on sale of assets	810	(13)	(86)
Income from operations	24,960	18,488	7,641
Interest and other (income) expense:
Interest expense	1,282	1,130	1,574
Other (income) expense, net	(83)	(180)	(203)
Income (loss) from operations before income taxes	23,761	17,538	6,270
Provision (benefit) for income taxes	(97,117)	661	748
Net income (loss) from continuing operations	120,878	16,877	5,522
Net loss from discontinued operations	0	(339)	(198)
Net Income (loss)	120,878	16,538	5,324
Net income attributable to noncontrolling interest	100	0	0
Net Income Attributable to IES Holdings	120,778	16,538	5,324
Unrealized gain (loss) on interest hedge, net of tax	0	2	(19)
Comprehensive income attributable to IES Holdings, Inc.	$ 120,778	$ 16,540	$ 5,305
Basic earnings (loss) per share:
Continuing operations	$ 5.63	$ 0.79	$ 0.3
Discontinued operations	0	(0.02)	(0.01)
Earnings Per Share, Basic	5.63	0.77	0.29
Diluted earnings (loss) per share:
Continuing operations	5.62	0.79	0.3
Discontinued operations	0	(0.02)	(0.01)
Earnings Per Share, Diluted	$ 5.62	$ 0.77	$ 0.29
Shares used in the computation of income (loss) per share
Basic	21,279,342	21,480,622	18,417,564
Diluted	21,492,339	21,526,188	18,473,420