Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Revenues	$ 205,677	$ 203,662	$ 403,977	$ 395,840
Cost of services	171,837	171,848	337,073	328,844
Gross profit	33,840	31,814	66,904	66,996
Selling, general and administrative expenses	29,647	30,120	59,736	58,314
Contingent consideration expense	71	83	71	83
Loss (gain) on sale of assets	(20)	(6)	(34)	(13)
Income from operations	4,142	1,617	7,131	8,612
Interest and other (income) expense:
Interest expense	473	428	914	874
Other (income) expense, net	(43)	(44)	(141)	(48)
Income from operations before income taxes	3,712	1,233	6,358	7,786
Provision (benefit) for income taxes	1,425	682	33,584	3,311
Net Income (loss)	2,287	551	(27,226)	4,475
Net income attributable to noncontrolling interest	66	15	122	67
Comprehensive income (loss) attributable to IES Holdings, Inc.	$ 2,221	$ 536	$ (27,348)	$ 4,408
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
Shares used in the computation of earnings (loss) per share
Basic	21,182,268	21,299,098	21,189,641,000	21,292,523
Diluted	21,440,570	21,574,155	21,189,641,000	21,560,678