Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenues	$ 282,633	$ 232,576	$ 783,389	$ 636,553
Cost of services	236,236	190,039	652,156	527,112
Gross profit	46,397	42,537	131,233	109,441
Selling, general and administrative expenses	36,333	32,372	103,489	92,108
Contingent consideration	(163)	81	(278)	152
Loss (gain) on sale of assets	(8)	(5)	87	(39)
Operating income (loss)	10,235	10,089	27,935	17,220
Interest expense	451	513	1,533	1,427
Other (income) expense, net	(64)	(111)	(129)	(252)
Income (loss) from operations before income taxes	9,848	9,687	26,531	16,045
Provision for (benefit from) income taxes	(1,207)	1,038	3,036	34,622
Net income (loss)	11,055	8,649	23,495	(18,577)
Net income attributable to noncontrolling interest	(83)	(133)	(150)	(255)
Comprehensive income attributable to IES Holdings, Inc.	$ 10,972	$ 8,516	$ 23,345	$ (18,832)
Earnings Per Share, Basic	$ 0.52	$ 0.40	$ 1.10	$ (0.89)
Earnings Per Share, Diluted	$ 0.52	$ 0.40	$ 1.09	$ (0.89)
Weighted Average Number of Shares Outstanding, Basic	21,043,425	21,200,635	21,139,697	21,193,306
Weighted Average Number of Shares Outstanding, Diluted	21,301,235	21,331,883	21,382,178	21,193,306