Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenues	$ 293,125	$ 282,633	$ 860,445	$ 783,389
Cost of services	234,805	236,236	700,646	652,156
Gross profit	58,320	46,397	159,799	131,233
Selling, general and administrative expenses	44,261	36,333	124,169	103,489
Contingent consideration	0	(163)	0	(278)
Loss (gain) on sale of assets	(3)	(8)	(40)	87
Operating income (loss)	14,062	10,235	35,670	27,935
Interest expense	269	451	828	1,533
Other (income) expense, net	(232)	(64)	177	(129)
Income (loss) from operations before income taxes	14,025	9,848	34,665	26,531
Provision for (benefit from) income taxes	1,695	(1,207)	7,592	3,036
Net income (loss)	12,330	11,055	27,073	23,495
Net income attributable to noncontrolling interest	(70)	(83)	(80)	(150)
Comprehensive income attributable to IES Holdings, Inc.	$ 12,260	$ 10,972	$ 26,993	$ 23,345
Earnings Per Share, Basic	$ 0.58	$ 0.52	$ 1.28	$ 1.10
Earnings Per Share, Diluted	$ 0.58	$ 0.52	$ 1.26	$ 1.09
Weighted Average Number of Shares Outstanding, Basic	20,728,149	21,043,425	20,819,857	21,139,697
Weighted Average Number of Shares Outstanding, Diluted	20,996,732	21,301,235	21,084,267	21,382,178