Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Revenues	$ 2,377,227	$ 2,166,808	$ 1,536,493
Cost of services	1,932,688	1,847,878	1,248,495
Gross profit	444,539	318,930	287,998
Selling, general and administrative expenses	298,625	262,714	202,251
Contingent consideration	277	277	211
Loss (gain) on sale of assets	(14,139)	(69)	(47)
Operating income	159,776	56,008	85,583
Interest Expense	3,022	2,970	962
Other (income) expense, net	(1,794)	37	(286)
Income from operations before income taxes	158,548	53,001	84,907
Provision for income taxes	38,761	12,815	16,231
Net income (loss)	119,787	40,186	68,676
Net (income) loss attributable to noncontrolling interest	(11,499)	(5,424)	(2,018)
Comprehensive income (loss) attributable to IES Holdings, Inc.	$ 108,288	$ 34,762	$ 66,658
Earnings (loss) per share, basic	$ 4.58	$ 1.45	$ 3.19
Earnings (loss) per share, diluted	$ 4.54	$ 1.44	$ 3.15
Weighted Average Number of Shares Outstanding, Basic	20,196,850	20,667,745	20,790,307
Weighted Average Number of Shares Outstanding, Diluted	20,413,032	20,894,625	21,086,432
Net income (loss) attributable to IES Holdings, Inc.	$ 108,288	$ 34,762	$ 66,658