Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 291,277	$ 256,914	$ 567,320	$ 500,756
Cost of services	240,013	213,679	465,841	415,920
Gross profit	51,264	43,235	101,479	84,836
Selling, general and administrative expenses	42,036	35,070	79,908	67,156
Contingent consideration	0	(149)	0	(115)
Loss (gain) on sale of assets	(1)	98	(37)	95
Operating income (loss)	9,229	8,216	21,608	17,700
Interest expense	320	535	559	1,082
Other (income) expense, net	268	(112)	409	(65)
Income (loss) from operations before income taxes	8,641	7,793	20,640	16,683
Provision for (benefit from) income taxes	2,428	2,336	5,897	4,243
Net income (loss)	6,213	5,457	14,743	12,440
Net income attributable to noncontrolling interest	18	32	(10)	(67)
Comprehensive income attributable to IES Holdings, Inc.	$ 6,231	$ 5,489	$ 14,733	$ 12,373
Earnings Per Share, Basic	$ 0.30	$ 0.26	$ 0.70	$ 0.58
Earnings Per Share, Diluted	$ 0.29	$ 0.26	$ 0.69	$ 0.58
Weighted Average Number of Shares Outstanding, Basic	20,847,245	21,139,096	20,865,460	21,187,834
Weighted Average Number of Shares Outstanding, Diluted	21,122,310	21,379,746	21,132,519	21,424,522