0001048268-26-000086 | 10-Q | XBRL Viewer

Subsequent Events (Details) $ in Thousands	Jan. 21, 2025 USD ($) Rate
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity \| $	$ 300
Minimum [Member] \| Pricing Level III
Subsequent Event [Line Items]
Line of Credit Facility, Interest Rate Description	100.00%
Minimum [Member] \| Pricing Level II
Subsequent Event [Line Items]
Line of Credit Facility, Interest Rate Description	175.00%
Minimum [Member] \| Pricing Level I
Subsequent Event [Line Items]
Line of Credit Facility, Interest Rate Description	250.00%
Maximum [Member] \| Pricing Level III
Subsequent Event [Line Items]
Line of Credit Facility, Interest Rate Description	175.00%
Maximum [Member] \| Pricing Level II
Subsequent Event [Line Items]
Line of Credit Facility, Interest Rate Description	250.00%
Maximum [Member] \| Pricing Level IV
Subsequent Event [Line Items]
Line of Credit Facility, Interest Rate Description	100.00%
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate \| Pricing Level III
Subsequent Event [Line Items]
Credit Agreement Interest Margin Rate	1.75%
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate \| Pricing Level II
Subsequent Event [Line Items]
Credit Agreement Interest Margin Rate	2.00%
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate \| Pricing Level IV
Subsequent Event [Line Items]
Credit Agreement Interest Margin Rate	1.50%
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate \| Pricing Level I
Subsequent Event [Line Items]
Credit Agreement Interest Margin Rate	2.25%
Base Rate \| Pricing Level III
Subsequent Event [Line Items]
Credit Agreement Interest Margin Rate	0.75%
Base Rate \| Pricing Level II
Subsequent Event [Line Items]
Credit Agreement Interest Margin Rate	1.00%
Base Rate \| Pricing Level IV
Subsequent Event [Line Items]
Credit Agreement Interest Margin Rate	0.50%
Base Rate \| Pricing Level I
Subsequent Event [Line Items]
Credit Agreement Interest Margin Rate	1.25%

Cash Flows, Supplemental Disclosures - USD ($)
$ in Thousands

6 Months Ended

Mar. 31, 2026

Mar. 31, 2025

Supplemental Cash Flow Elements [Abstract]

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

$ 19,701

$ 27,795

Right-of-Use Asset Obtained in Exchange for Finance Lease Liability

$ 773

$ 465

Schedule of Cash Flow, Supplemental Disclosures

Cash and noncash activities in the six months ended March 31, 2026 and 2025 were as follows:


		Six Months Ended March 31,
		2026		2025
SUPPLEMENTAL DISCLOSURE OF CASH ACTIVITIES:
	Cash paid for interest	$	1,459	$	355
	Cash paid for income taxes, net	$	34,616	$	64,197

SUPPLEMENTAL DISCLOSURE OF NONCASH ACTIVITIES:



	Right-of-use assets obtained in exchange for new operating lease liabilities	$	19,701	$	27,795
	Right-of-use assets obtained in exchange for new finance lease liabilities	$	773	$	465

Statement of Cash Flows, Supplemental Disclosures

6 Months Ended

Mar. 31, 2026

Supplemental Cash Flow Elements [Abstract]

Cash Flow, Supplemental Disclosures

SUPPLEMENTAL CASH FLOW INFORMATION

Cash and noncash activities in the six months ended March 31, 2026 and 2025 were as follows:


		Six Months Ended March 31,
		2026		2025
SUPPLEMENTAL DISCLOSURE OF CASH ACTIVITIES:
	Cash paid for interest	$	1,459	$	355
	Cash paid for income taxes, net	$	34,616	$	64,197

SUPPLEMENTAL DISCLOSURE OF NONCASH ACTIVITIES:



	Right-of-use assets obtained in exchange for new operating lease liabilities	$	19,701	$	27,795
	Right-of-use assets obtained in exchange for new finance lease liabilities	$	773	$	465

Per Share Information

6 Months Ended

Mar. 31, 2026

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

5. PER SHARE INFORMATION

The following table reconciles the components of basic and diluted earnings per share for the three and six months ended March 31, 2026 and 2025:


	Three Months Ended March 31,				Six Months Ended March 31,
	2026		2025		2026		2025
Numerator:
Net income attributable to IES Holdings, Inc.	$	109,909	$	70,652	$	201,348	$	126,955
(Increase) decrease in noncontrolling interest	(138)		86		(551)		(1,058)

Net income attributable to common stockholders of IES Holdings, Inc.	$	109,771	$	70,738	$	200,797	$	125,897

Denominator:
Weighted average common shares outstanding — basic	19,926,397		19,969,618		19,906,511		19,979,896
Effect of dilutive non-vested securities	259,988		243,824		273,195		249,981
Weighted average common and common equivalent shares outstanding — diluted	20,186,385		20,213,442		20,179,707		20,229,877

Earnings per share attributable to common stockholders of IES Holdings, Inc.:
Basic	$	5.51	$	3.54	$	10.09	$	6.30
Diluted	$	5.44	$	3.50	$	9.95	$	6.22

Potentially dilutive securities excluded from the computation of diluted earnings per share as the effect of their inclusion would have been anti-dilutive:
Employee phantom stock units	69		16,635		1,347		33,179

Revenue Recognition (Tables)

6 Months Ended

Mar. 31, 2026

Revenue Recognition and Deferred Revenue [Abstract]

Disaggregation of Revenue [Table Text Block]

Our consolidated revenue for the three and six months ended March 31, 2026 and 2025 was derived from the following activities. Certain prior period amounts have been reclassified to conform with the current period presentation, where applicable. See details in the following tables:


	Three Months Ended March 31,				Six Months Ended March 31,
	2026		2025			2026		2025
Communications	$	367,696	$	273,016		$	719,616	$	505,976
Residential
Single-family Electrical	134,202		160,065			271,181		329,282
Single-family Plumbing & HVAC	90,059		79,168			172,919		153,351
Multi-family and Other	63,355		78,733			127,560		155,304
Total Residential	287,616		317,966			571,660		637,937
Infrastructure Solutions
Industrial Services	40,687		29,178			64,878		47,846
Custom Engineered Solutions	151,761		88,442			267,745		177,899
Total Infrastructure Solutions	192,448		117,620			332,623		225,745
Commercial & Industrial	126,524		125,358			221,343		213,849
Total revenue	$	974,284	$	833,960		$	1,845,242	$	1,583,507


	Three Months Ended March 31, 2026
		Communications		Residential		Infrastructure Solutions		Commercial & Industrial		Total
Fixed-price		$	219,657	$	287,616	$	163,624	$	112,454	$	783,351
Time-and-material		148,039		—		28,824		14,070		190,933
Total revenue		$	367,696	$	287,616	$	192,448	$	126,524	$	974,284

	Three Months Ended March 31, 2025
		Communications		Residential		Infrastructure Solutions		Commercial & Industrial		Total
Fixed-price		$	202,412	$	317,966	$	106,477	$	107,516	$	734,371
Time-and-material		70,604		—		11,143		17,842		99,589
Total revenue		$	273,016	$	317,966	$	117,620	$	125,358	$	833,960

Inventory (Tables)

6 Months Ended

Mar. 31, 2026

Inventory Disclosure [Abstract]

Schedule of Inventory, Current [Table Text Block]

Inventories consist of the following components:


	March 31,		September 30,
	2026		2025
Raw materials	$	35,916	$	30,231
Work in process		13,726		10,546
Finished goods		10,978		8,158
Parts and supplies		66,059		62,601
Total inventories	$	126,679	$	111,536

Goodwill and Intangible Assets Goodwill (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2026 USD ($)
Goodwill [Line Items]
Goodwill	$ 107,830
Goodwill	129,190
Goodwill, Acquired During Period	21,360
Commercial and Industrial [Member]
Goodwill [Line Items]
Goodwill	0
Goodwill	0
Goodwill, Acquired During Period	0
Residential [Member]
Goodwill [Line Items]
Goodwill	51,370
Goodwill	51,370
Goodwill, Acquired During Period	0
Infrastructure Solutions [Member]
Goodwill [Line Items]
Goodwill	44,124
Goodwill	65,484
Goodwill, Acquired During Period	21,360
Communications [Member]
Goodwill [Line Items]
Goodwill	12,336
Goodwill	12,336
Goodwill, Acquired During Period	$ 0

- Definition

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

+ References

+ Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

Debt (Details) - USD ($) $ in Thousands	Jan. 21, 2025	Mar. 31, 2026	Sep. 30, 2025
Debt Disclosure [Abstract]
Long-term debt		$ 0	$ 0
Letters of Credit Outstanding, Amount		11,335
Line of Credit Facility, Remaining Borrowing Capacity		253,665
Line of Credit Facility, Maximum Borrowing Capacity	$ 300
Line of Credit Facility [Line Items]
Consolidated Total Leverage Ratio, Maximum	300.00%
Consolidated Interest Coverage Ratio, Minimum	300.00%
Line of Credit Facility, Maximum Borrowing Capacity	$ 300
Consolidated Total Leverage Ratio, Restrictive Covenant	275.00%
Long-term debt		$ 0	$ 0
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.25%
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.35%

Investments, Debt and Equity Securities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Trading, Unrealized Gain (Loss)		$ (66)	$ 0	$ (33)
Unrealized Gain (Loss) on Investments	$ 17,706	5,481	34,621	7,829
Marketable Securities [Line Items]
Equity Securities, FV-NI	213,983		213,983		$ 104,587
Marketable Securities, Current	213,983		213,983		$ 104,587
Equity Securities, FV-NI, Unrealized Gain (Loss)	$ 17,706	$ 5,547	$ 34,621	$ 7,862

- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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+ Details

Operating Segments (Details) $ in Thousands	3 Months Ended		6 Months Ended
Operating Segments (Details) $ in Thousands	Mar. 31, 2026 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2026 USD ($) business	Mar. 31, 2025 USD ($)	Sep. 30, 2025 USD ($)
Segment Reporting [Line Items]
Cost of services	$ 719,497	$ 625,091	$ 1,370,440	$ 1,196,611
Gross profit	254,787	208,869	474,802	386,896
Selling, general and administrative expenses	142,442	116,044	264,257	219,083
Contingent consideration	129	339	258	678
Loss (gain) on sale of assets	(39)	(209)	299	(179)
Operating income (loss)	112,255	92,695	209,988	167,314
Depreciation and amortization expense	16,091	11,948	28,765	23,035
Capital expenditures	31,833	16,953	78,407	30,122
Total assets	1,994,038	1,364,559	1,994,038	1,364,559	$ 1,595,661
Revenues	974,284	833,960	1,845,242	1,583,507
Noncontrolling Interest, Change in Redemption Value			$ 723	1,401
Number of Reportable Segments \| business			4
Commercial and Industrial [Member]
Segment Reporting [Line Items]
Cost of services	90,379	98,505	$ 165,047	171,880
Gross profit	36,145	26,853	56,296	41,969
Selling, general and administrative expenses	14,751	11,024	25,268	19,088
Loss (gain) on sale of assets	(33)	(23)	(102)	(27)
Operating income (loss)	21,427	15,852	31,130	22,908
Depreciation and amortization expense	1,059	612	1,989	1,185
Capital expenditures	3,515	2,149	5,443	5,131
Total assets	220,919	121,990	220,919	121,990
Revenues	126,524	125,358	221,343	213,849
Communications [Member]
Segment Reporting [Line Items]
Cost of services	273,970	209,973	539,500	394,122
Gross profit	93,726	63,043	180,116	111,854
Selling, general and administrative expenses	32,567	23,441	61,007	43,679
Loss (gain) on sale of assets	(1)	(21)	512	(59)
Operating income (loss)	61,160	39,623	118,597	68,234
Depreciation and amortization expense	1,836	1,255	3,644	2,458
Capital expenditures	22,296	6,372	44,834	11,052
Total assets	472,610	343,356	472,610	343,356
Revenues	367,696	273,016	719,616	505,976
Infrastructure Solutions [Member]
Segment Reporting [Line Items]
Cost of services	129,328	78,319	218,962	151,472
Gross profit	63,120	39,301	113,661	74,273
Selling, general and administrative expenses	21,050	12,487	35,957	23,755
Contingent consideration	129	339	258	678
Loss (gain) on sale of assets	(2)	(9)	(97)	70
Operating income (loss)	41,943	26,484	77,543	49,770
Depreciation and amortization expense	6,482	3,942	10,386	7,615
Capital expenditures	4,617	2,999	6,909	5,110
Total assets	582,557	328,027	582,557	328,027
Revenues	192,448	117,620	332,623	225,745
Residential [Member]
Segment Reporting [Line Items]
Cost of services	225,820	238,294	446,931	479,137
Gross profit	61,796	79,672	124,729	158,800
Selling, general and administrative expenses	55,375	57,151	109,457	112,463
Contingent consideration	0	0	0	0
Loss (gain) on sale of assets	(3)	(156)	(14)	(163)
Operating income (loss)	6,424	22,677	15,286	46,500
Depreciation and amortization expense	6,363	5,913	12,081	11,324
Capital expenditures	1,361	3,748	2,701	6,089
Total assets	342,980	379,510	342,980	379,510
Revenues	287,616	317,966	571,660	637,937
Corporate Segment [Member]
Segment Reporting [Line Items]
Cost of services	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	18,699	11,941	32,568	20,098
Contingent consideration		0
Loss (gain) on sale of assets	0	0	0	0
Operating income (loss)	(18,699)	(11,941)	(32,568)	(20,098)
Depreciation and amortization expense	351	226	665	453
Capital expenditures	44	1,685	18,520	2,740
Total assets	374,972	191,676	374,972	191,676
Revenues	$ 0	$ 0	$ 0	$ 0

Per Share Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Earnings Per Share [Abstract]
Undistributed Earnings (Loss) Available to Common Shareholders, Basic	$ 109,771	$ 70,738	$ 200,797	$ 125,897
Noncontrolling Interest, Change in Redemption Value			(723)	(1,401)
Noncontrolling Interest, Period Increase (Decrease)	$ (138)	$ 86	$ (551)	$ (1,058)
Weighted Average Number of Shares Outstanding, Basic	19,926,397	19,969,618	19,906,511	19,979,896
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	259,988	243,824	273,195	249,981
Weighted Average Number of Shares Outstanding, Diluted	20,186,385	20,213,442	20,179,707	20,229,877
Earnings Per Share, Basic	$ 5.51	$ 3.54	$ 10.09	$ 6.30
Earnings Per Share, Diluted	$ 5.44	$ 3.50	$ 9.95	$ 6.22
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	$ 109,909	$ 70,652	$ 201,348	$ 126,955
Phantom Share Units (PSUs) [Member]
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	69	16,635	1,347	33,179
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	69	16,635	1,347	33,179

Business	6 Months Ended
Business	Mar. 31, 2026
Accounting Policies [Abstract]
Accounting Standards Update and Change in Accounting Principle	Recent Accounting Pronouncements and Disclosure Rules Not Yet Adopted In December 2023, the FASB issued Accounting Standard Update No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). This standard requires more detailed disclosure within the tax rate reconciliation table, as well as additional information about cash taxes paid. This update is effective for fiscal years beginning after December 15, 2024. Early adoption is permitted. We are evaluating the impact this update will have on our annual disclosures; however, it will not impact our financial condition, results of operations, or cash flows. In November 2024, the FASB issued Accounting Standard Update No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (“ASU 2024-03”). This standard requires additional disclosures of certain expenses, including purchases of inventory, employee compensation, depreciation, intangible asset amortization, and other specific expense categories. This standard also requires disclosure of the total amount of selling expenses and the Company's definition of selling expenses. This update is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. We are evaluating the impact this update will have on our annual disclosures; however, it will not impact our financial condition, results of operations, or cash flows.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 20
-Name Accounting Standards Codification
-Section 65
-Paragraph 7
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480528/815-20-65-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 11.M.Q2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480530/250-10-S99-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 65
-Paragraph 3
-Subparagraph (e)(1)
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-URI https://asc.fasb.org/1943274/2147479719/606-10-65-3

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 65
-Paragraph 3
-Subparagraph (d)
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-URI https://asc.fasb.org/1943274/2147479719/606-10-65-3

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Section 65
-Paragraph 8
-Subparagraph (f)(1)
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482705/350-40-65-4

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147482705/350-40-65-4

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147479719/606-10-65-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147479719/606-10-65-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 65
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-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479279/805-10-65-5

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147479343/105-10-65-9

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147480336/718-10-65-17

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147480336/718-10-65-17

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147476176/805-60-65-1

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147480016/944-40-65-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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Reference 29: http://www.xbrl.org/2003/role/disclosureRef
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Reference 30: http://www.xbrl.org/2003/role/disclosureRef
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Reference 31: http://www.xbrl.org/2003/role/disclosureRef
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Reference 32: http://www.xbrl.org/2003/role/disclosureRef
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Reference 33: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147479654/326-10-65-4

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 6
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-URI https://asc.fasb.org/1943274/2147480530/250-10-S99-6

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 20
-Name Accounting Standards Codification
-Section 65
-Paragraph 4
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481538/470-20-65-4

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 65
-Paragraph 4
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481538/470-20-65-4

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-1

Reference 38: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 250
-Publisher FASB
-URI https://asc.fasb.org/250/tableOfContent

Reference 39: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480175/815-40-65-1

+ Details

Business (Details) - USD ($) $ in Thousands	6 Months Ended
Business (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025	Sep. 30, 2024
Accounting Policies [Abstract]
Redeemable Noncontrolling Interest, Equity, Redemption Value	$ 4,572
Accounting Standards Update and Change in Accounting Principle	Recent Accounting Pronouncements and Disclosure Rules Not Yet Adopted In December 2023, the FASB issued Accounting Standard Update No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”). This standard requires more detailed disclosure within the tax rate reconciliation table, as well as additional information about cash taxes paid. This update is effective for fiscal years beginning after December 15, 2024. Early adoption is permitted. We are evaluating the impact this update will have on our annual disclosures; however, it will not impact our financial condition, results of operations, or cash flows. In November 2024, the FASB issued Accounting Standard Update No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (“ASU 2024-03”). This standard requires additional disclosures of certain expenses, including purchases of inventory, employee compensation, depreciation, intangible asset amortization, and other specific expense categories. This standard also requires disclosure of the total amount of selling expenses and the Company's definition of selling expenses. This update is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. We are evaluating the impact this update will have on our annual disclosures; however, it will not impact our financial condition, results of operations, or cash flows.
Redeemable Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest	$ 732	$ 3,318
Payments to Noncontrolling Interests	(890)	(4,967)
Noncontrolling Interest, Change in Redemption Value	723	1,401
Redeemable Noncontrolling Interest, Equity, Carrying Amount	4,572	$ 40,748	$ 4,007	$ 40,996
Noncontrolling Interest, Decrease from Deconsolidation	$ 40,000
Edmonson Electric
Redeemable Noncontrolling Interest [Line Items]
Subsidiary, Ownership Percentage, Noncontrolling Owner	20.00%
Subsidiary, Ownership Percentage, Parent	80.00%
NEXT Electric
Redeemable Noncontrolling Interest [Line Items]
Subsidiary, Ownership Percentage, Noncontrolling Owner	20.00%
Subsidiary, Ownership Percentage, Parent	80.00%

Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	$ 740		$ 740		$ 1,120
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(609)		(609)		(984)
Business Combination, Contingent Consideration, Liability, Noncurrent	(2,371)		(2,371)		(2,113)
Fair Value, Net Asset (Liability)	211,743		211,743		102,610
Equity Securities, FV-NI, Current	213,983		213,983		104,587
Equity Securities, FV-NI, Unrealized Gain (Loss)	17,706	$ 5,547	34,621	$ 7,862
Debt Securities, Trading, Unrealized Gain (Loss)		$ (66)	0	(33)
Equity Securities, FV-NI	213,983		213,983		104,587
Payments to Acquire Investments			0	$ 44,900
Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability, Noncurrent	(2,371)		(2,371)		(2,113)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings			$ 258
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Contingent consideration
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	740		$ 740		1,120
Financial and Nonfinancial Liabilities, Fair Value Disclosure	(609)		(609)		(984)
Fair Value, Net Asset (Liability)	214,114		214,114		104,723
Equity Securities, FV-NI, Current	213,983		213,983		104,587
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability, Noncurrent	(2,371)		(2,371)		(2,113)
Fair Value, Net Asset (Liability)	$ (2,371)		$ (2,371)		$ (2,113)

Business Combinations, Asset Acquisitions, Transaction between Entities under Common Control, and Joint Venture Formation (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
	Jan. 16, 2026	Mar. 31, 2026	Mar. 31, 2026
Business Combination [Line Items]
Goodwill, Acquired During Period			$ 21,360
Business Combination, Goodwill, Expected Tax Deductible, Amount	$ 3,342
Gulf Island
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]
Business Combination, Achieved in Stages, Description	We remeasured our previously held interest in Gulf Island to its fair value of $6,791 and realized a remeasurement gain of $2,818, representing the difference between the carrying value of that interest at September 30, 2025 and its fair value immediately prior to our acquisition of the remaining outstanding shares. Prior to the acquisition of the remaining outstanding shares of Gulf Island, we accounted for our initial investment as a trading security and recorded a gain or loss in each period to adjust the carrying value of the securities to fair value at each period end. The net impact of the change in value of our previously held interest in Gulf Island, inclusive of the final realized gain, was $17 and $2,818 for the three and six months ended March 31, 2026, and is included in Gain on marketable securities in the Company's Condensed Consolidated Statements of Comprehensive Income.
Business Combination [Line Items]
Goodwill, Acquired During Period	$ 21,360		21,360
Business Combination, Recognized Asset Acquired, Other Asset, Noncurrent	2,488
Business Combination, Acquiree's Earnings (Loss) since Acquisition Date, Actual		$ 1,185	1,185
Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment	78,968
Business Combination, Recognized Asset Acquired, Deferred Tax Asset	6,110
Business Combination, Consideration Transferred and Preacquisition Equity Interest in Acquiree	152,042
Business Combination, Recognized Asset Acquired, Receivable, Current	21,973
Business Combination, Recognized Asset Acquired, Asset, Current	17,156
Business Combination, Recognized Liability Assumed, Liability, Noncurrent	(1,263)
Business Combination, Recognized Liability Assumed, Liability, Current	(19,160)
Business Combination, Acquiree's Revenue since Acquisition Date, Actual		$ 37,493	$ 37,493
Business Combination, Consideration Transferred, Liabilities Incurred	2,143
Business Combination, Consideration Transferred, Equity Interest	6,791
Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill	$ 152,042
Business Combination, Voting Equity Interest Acquired, Percentage	100.00%
Business Combination, Achieved in Stages, Description	We remeasured our previously held interest in Gulf Island to its fair value of $6,791 and realized a remeasurement gain of $2,818, representing the difference between the carrying value of that interest at September 30, 2025 and its fair value immediately prior to our acquisition of the remaining outstanding shares. Prior to the acquisition of the remaining outstanding shares of Gulf Island, we accounted for our initial investment as a trading security and recorded a gain or loss in each period to adjust the carrying value of the securities to fair value at each period end. The net impact of the change in value of our previously held interest in Gulf Island, inclusive of the final realized gain, was $17 and $2,818 for the three and six months ended March 31, 2026, and is included in Gain on marketable securities in the Company's Condensed Consolidated Statements of Comprehensive Income.
Business Combination, Consideration Transferred, Tangible and Intangible Assets, Excluding Cash	$ 143,108
Business Combination, Voting Equity Interest Acquired, Percentage	100.00%
Gulf Island \| Trade name
Business Combination [Line Items]
Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Excluding Goodwill	$ 4,890
Gulf Island \| Customer Relationships [Member]
Business Combination [Line Items]
Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Excluding Goodwill	$ 19,520
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	8 years
Gulf Island \| Trade Names
Business Combination [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	4 years

Fair Value Measurements (Tables)

6 Months Ended

Mar. 31, 2026

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

Financial assets (liabilities) measured at fair value on a recurring basis as of March 31, 2026 and September 30, 2025, are summarized in the following tables by the type of inputs applicable to the fair value measurements:


	March 31, 2026
			Total Fair Value		Quoted Prices (Level 1)		Significant Unobservable Inputs (Level 3)
Equity securities		$	213,983	$	213,983	$	—


Executive savings plan assets			740		740		—
Executive savings plan liabilities			(609)		(609)		—
Contingent consideration liability			(2,371)		—		(2,371)
Total		$	211,743	$	214,114	$	(2,371)


	September 30, 2025
			Total Fair Value		Quoted Prices (Level 1)		Significant Unobservable Inputs (Level 3)
Equity securities		$	104,587	$	104,587	$	—

Executive savings plan assets			1,120		1,120		—

Executive savings plan liabilities			(984)		(984)		—

Contingent consideration liability			(2,113)		—		(2,113)
Total		$	102,610	$	104,723	$	(2,113)

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation

The table below presents the change in fair value of liabilities measured using significant unobservable inputs (Level 3).












	Contingent consideration liability
Fair value at September 30, 2025	$	(2,113)

Net adjustments to fair value included in “Contingent consideration”	(258)

Fair value at March 31, 2026	$	(2,371)

Business (Tables)

6 Months Ended

Mar. 31, 2026

Accounting Policies [Abstract]

Redeemable Noncontrolling Interest

The activity in redeemable noncontrolling interest for the six months ended March 31, 2026 and 2025 is summarized in the table below.


	Six Months Ended March 31,
	2026		2025
Balance at beginning of period	$	4,007	$	40,996
Net income attributable to noncontrolling interests	732		3,318
Distributions to noncontrolling interests	(890)		(4,967)
Adjustments to record noncontrolling interests at redemption value	723		1,401


Balance at end of period	$	4,572	$	40,748

Investments, Equity Method and Joint Ventures (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Dec. 02, 2024	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Investments				$ 0	$ 44,900
Equity Method Investments		$ 63,888		63,888		$ 59,662
Income (Loss) from Equity Method Investments				$ 4,226	$ 0
CB&I
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Investments	$ 44,900
Equity Method Investment, Ownership Percentage		12.50%		12.50%
Equity Method Investments		$ 63,888		$ 63,888
Income (Loss) from Equity Method Investments		$ 0	$ 0

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References + Details

- Definition

Amount of income (loss) for proportionate share of equity method investee's income (loss).

+ References + Details

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483499/205-20-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Investments, Equity Method and Joint Ventures

6 Months Ended

Mar. 31, 2026

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investments and Joint Ventures Disclosure

Equity Method Investments

On December 2, 2024, we paid $44,900 to acquire a 12.5% membership interest in Jett Texas Company LLC (“Jett”), an investment company, as part of the financing of Jett's investment in the CB&I storage solutions business, a designer and builder of storage facilities, tanks and terminals for energy and industrial markets, formerly owned by McDermott International, Ltd. Our investment, which is included in “Investments” on our Condensed Consolidated Balance Sheets, is measured using the equity method of accounting, wherein the carrying value of our investment is initially recorded at cost basis and subsequently adjusted for our proportionate share of earnings or losses, additional investments, and distributions. We recorded no earnings on our investment in Jett in the three months ended March 31, 2026 and $4,226 in the six months ended March 31, 2026 and the carrying value of our investment in Jett was $63,888 at March 31, 2026.

Investment in Debt and Equity Securities and Other Trading Assets [Text Block]

Investments in Marketable Securities

Investments in marketable equity and debt securities classified as trading securities, which were included in “Marketable securities” in our Condensed Consolidated Balance Sheets, are measured at fair value on a recurring basis and classified within Level 1 of the fair value hierarchy, because we use quoted prices of identical assets in active markets. For more information, refer to Note 9, “Fair Value Measurements.” The balance of our marketable securities was as follows:


	March 31, 2026		September 30, 2025
Marketable equity securities	$	213,983	$	104,587

Gains and losses to measure our investments in marketable equity and debt securities at fair value were included in “Gain on marketable securities” on our Condensed Consolidated Statements of Comprehensive Income. Our unrealized net gains (losses), which are calculated as total net gains (losses) recognized during the period less net gains (losses) recognized on securities sold during the period, were as follows:


	Three Months Ended March 31,				Six Months Ended March 31,
	2026		2025		2026		2025
Unrealized gain on marketable equity securities	$	17,706	$	5,547	$	34,621	$	7,862
Unrealized loss on marketable debt securities	—		(66)		—		(33)

Total unrealized gain on marketable securities	$	17,706	$	5,481	$	34,621	$	7,829

Goodwill and Intangible Assets Intangibles (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Jan. 16, 2026	Sep. 30, 2025
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, before Accumulated Amortization	$ 141,578		$ 117,168
Intangible Asset, Finite-Lived, Accumulated Amortization	(83,132)		(75,523)
Intangible Asset, Excluding Goodwill, after Accumulated Amortization	58,446		41,645
Trademarks and Trade Names [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, before Accumulated Amortization	21,089		16,199
Intangible Asset, Finite-Lived, Accumulated Amortization	(9,653)		(8,549)
Intangible Asset, Excluding Goodwill, after Accumulated Amortization	$ 11,436		$ 7,650
Trademarks and Trade Names [Member] \| Minimum [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, Useful Life	5 years		5 years
Trademarks and Trade Names [Member] \| Maximum [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, Useful Life	20 years		20 years
Technical Library
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, Useful Life	20 years		20 years
Intangible Asset, Finite-Lived, before Accumulated Amortization	$ 400		$ 400
Intangible Asset, Finite-Lived, Accumulated Amortization	(251)		(241)
Intangible Asset, Excluding Goodwill, after Accumulated Amortization	$ 149		$ 159
Noncompete Agreements [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, Useful Life	5 years		5 years
Intangible Asset, Finite-Lived, before Accumulated Amortization	$ 940		$ 940
Intangible Asset, Finite-Lived, Accumulated Amortization	(125)		(31)
Intangible Asset, Excluding Goodwill, after Accumulated Amortization	815		909
Backlog [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, before Accumulated Amortization	1,257		1,257
Intangible Asset, Finite-Lived, Accumulated Amortization	(910)		(678)
Intangible Asset, Excluding Goodwill, after Accumulated Amortization	$ 347		$ 579
Backlog [Member] \| Minimum [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, Useful Life	1 year		1 year
Backlog [Member] \| Maximum [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, Useful Life	2 years		2 years
Customer Relationships [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, before Accumulated Amortization	$ 117,892		$ 98,372
Intangible Asset, Finite-Lived, Accumulated Amortization	(72,193)		(66,024)
Intangible Asset, Excluding Goodwill, after Accumulated Amortization	$ 45,699		$ 32,348
Customer Relationships [Member] \| Gulf Island
Intangible Asset, Finite-Lived [Line Items]
Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Excluding Goodwill		$ 19,520
Customer Relationships [Member] \| Minimum [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, Useful Life	1 year		1 year
Customer Relationships [Member] \| Maximum [Member]
Intangible Asset, Finite-Lived [Line Items]
Intangible Asset, Finite-Lived, Useful Life	15 years		15 years

Stockholders' Equity

6 Months Ended

Mar. 31, 2026

Equity [Abstract]

Shareholders' Equity and Share-based Payments [Text Block]

7. STOCKHOLDERS’ EQUITY

Equity Incentive Plan

The Company’s 2006 Equity Incentive Plan, as amended and restated (the “Equity Incentive Plan”), provides for grants of phantom stock units, performance awards and stock options as well as grants of stock, including restricted stock. The Equity Incentive Plan was amended and restated effective February 20, 2025 following approval by stockholders at the Company's 2025 Annual Meeting of Stockholders to, among other things, authorize the issuance of an additional 750,000 shares under the Equity Incentive Plan and extend its term to February 19, 2035. As of March 31, 2026, approximately 1,299,355 shares were authorized and available for issuance.

Stock Repurchase Program

On July 31, 2024, our Board authorized a stock repurchase program for the purchase from time to time of up to $200,000 of the Company’s common stock after the previous stock repurchase program was fully utilized. Share purchases are made for cash in open market transactions at prevailing market prices or in privately negotiated transactions or otherwise. The timing and amount of purchases under the program are determined based upon prevailing market conditions, our liquidity requirements, contractual restrictions and other factors. All or part of the repurchases may be implemented under a Rule 10b5-1 trading plan, which allows repurchases under predetermined terms at times when the Company might otherwise be prevented from purchasing under insider trading laws or because of self-imposed blackout periods. The program does not require the Company to purchase any specific number of shares and may be modified, suspended, reinstated, or terminated at any time at the Company’s discretion and without notice. We repurchased 4,112 shares of common stock during both the three and six months ended March 31, 2026 in open market transactions at an average price of $418.31. We repurchased 118,314 and 139,362 shares of our common stock during the three and six months ended March 31, 2025 in open market transactions at an average price of $172.80 and $178.40 per share, respectively.

Treasury Stock

During the six months ended March 31, 2026, we issued 121,139 shares of common stock from treasury stock to employees and repurchased 47,603 shares of common stock from our employees to satisfy statutory tax withholding requirements upon the vesting of certain phantom stock units under the Equity Incentive Plan.

During the six months ended March 31, 2025, we issued 94,752 shares of common stock from treasury stock to employees and repurchased 38,744 shares of common stock from our employees to satisfy statutory tax withholding requirements upon the vesting of certain phantom stock units under the Equity Incentive Plan.

Director Stock Compensation

Members of our Board of Directors receive a portion of their overall compensation as either grants of common stock or as Director phantom stock units (“Director PSUs”). The Director PSUs are contractual rights to receive one share of the Company's common stock and are paid via unrestricted stock grants to each director upon their departure from the Board of Directors, or upon a change in control. We record compensation expense for the full value of the grant on the date of grant.

Employee Phantom Stock Units

An employee phantom stock unit (an “Employee PSU”) is a contractual right to receive one share of the Company’s common stock. Depending on the terms of each grant, Employee PSUs may vest upon the achievement of certain specified performance objectives and continued performance of services, or may vest based on continued performance of services through the vesting date.

A summary of Employee PSU activity for the six months ended March 31, 2026 is provided in the table below:


Unvested at September 30, 2025			306,755
Granted			15,680
Vested			(121,010)
Forfeited			(2,566)
Unvested at March 31, 2026			198,859

A summary of the compensation expense related to our stock awards recognized during the three and six months ended March 31, 2026 and 2025 is provided in the table below:


	Three Months Ended March 31,				Six Months Ended March 31,
	2026		2025		2026		2025

Director PSUs	$	132	$	159	$	290	$	319
Employee PSUs	$	3,366	$	2,980	$	6,935	$	4,766
Director common stock grants	$	52	$	—	$	91	$	—

DEI Document - shares	6 Months Ended
DEI Document - shares	Mar. 31, 2026	Apr. 27, 2026
Entity Information [Line Items]
Entity File Number	001-13783
Entity Registrant Name	IES Holdings, Inc.
Document Period End Date	Mar. 31, 2026
Document Quarterly Report	true
Document Transition Report	false
Entity Central Index Key	0001048268
Entity Incorporation, State or Country Code	DE
Document Type	10-Q
Amendment Flag	false
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Tax Identification Number	76-0542208
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	IESC
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Address, Address Line One	13131 Dairy Ashford Rd.
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Sugar Land
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77478
City Area Code	713
Local Phone Number	860-1500
Entity Common Stock, Shares Outstanding		19,923,887

Inventory

6 Months Ended

Mar. 31, 2026

Inventory Disclosure [Abstract]

Inventory Disclosure [Text Block]

10. INVENTORY

Inventories consist of the following components:


	March 31,		September 30,
	2026		2025
Raw materials	$	35,916	$	30,231
Work in process		13,726		10,546
Finished goods		10,978		8,158
Parts and supplies		66,059		62,601
Total inventories	$	126,679	$	111,536

Accounting Policies (Policies)	6 Months Ended
Accounting Policies (Policies)	Mar. 31, 2026
Accounting Policies [Abstract]
Use of Estimates, Policy	Use of Estimates The preparation of financial statements in conformity with GAAP requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, disclosures of contingent liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Estimates are primarily used in our revenue recognition of construction in progress, fair value assumptions in accounting for business combinations, stock-based compensation, reserves for legal matters, and realizability of deferred tax assets and unrecognized tax benefits.
Equity Method Investments	Equity Method Investments We account for investments using the equity method of accounting if the investment gives us the ability to exercise significant influence over an investee but does not grant us control. Significant influence generally exists when an investor owns 20% or more of the voting stock of an incorporated investee or a more than 3% to 5% interest in an unincorporated investee. Under the equity method of accounting, the carrying amount of an investment is initially recorded at cost basis and is subsequently adjusted for our proportionate share of earnings or losses, additional investments in the entity, and distributions. Our proportionate share of earnings or losses is recorded in Equity method investment income on our Condensed Consolidated Statements of Comprehensive Income.

- Definition

Disclosure of accounting policy for the use of estimates in the preparation of financial statements in conformity with generally accepted accounting principles.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
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+ Details

Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Sep. 30, 2025
Inventory Disclosure [Abstract]
Inventory, Raw Materials, Gross	$ 35,916	$ 30,231
Inventory, Work in Process, Gross	13,726	10,546
Inventory, Finished Goods, Gross	10,978	8,158
Other Inventory, Gross	66,059	62,601
Inventory, Net	$ 126,679	$ 111,536

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Sep. 30, 2025
Commitments and Contingencies Disclosure [Abstract]
Accrued Insurance, Current	$ 13,544	$ 12,131
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	11,335
Revenue, Remaining Performance Obligation, Amount	2,347,101
Estimated cost of completion of bonded projects	312,385
Estimated cost of completion of bonded projects	312,385
Inventory, Firm Purchase Commitment, Loss	15,773
Insurance Related [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	$ 11,335	$ 5,545

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Goodwill and Intangible Assets

6 Months Ended

Mar. 31, 2026

Intangible Asset, Goodwill and Other [Abstract]

Intangible Asset and Goodwill [Text Block]

11. GOODWILL AND INTANGIBLE ASSETS

Goodwill

The following summarizes the changes in the carrying value of goodwill by segment during the six months ended March 31, 2026:


	Communications		Residential		Infrastructure Solutions			Commercial & Industrial		Total
Goodwill at September 30, 2025	$	12,336	$	51,370	$	44,124		$	—	$	107,830
Acquisitions	—		—		21,360		(1)	—		21,360



Goodwill at March 31, 2026	$	12,336	$	51,370	$	65,484		$	—	$	129,190

(1) On January 16, 2026, the Company acquired all of the outstanding common stock of Gulf Island Fabrication, Inc. for a purchase price of $152,042, net of cash acquired. The valuation of goodwill is preliminary as of the date of this report, and is subject to change.

Intangible Assets

Intangible assets consist of the following:


	Estimated Useful Lives (in Years)			March 31, 2026
					Gross Carrying Amount		Accumulated Amortization		Net
Trademarks/trade names	5	-	20		$	21,089	$	(9,653)		$	11,436
Technical library	20				400		(251)			149
Customer relationships	1	-	15		117,892		(72,193)			45,699
Non-competition arrangements	5				940		(125)			815
Backlog and construction contracts	1	-	2		1,257		(910)			347
Total intangible assets					$	141,578	$	(83,132)		$	58,446


	Estimated Useful Lives (in Years)			September 30, 2025
					Gross Carrying Amount		Accumulated Amortization		Net
Trademarks/trade names	5	-	20		$	16,199	$	(8,549)		$	7,650
Technical library	20				400		(241)			159
Customer relationships	1	-	15		98,372		(66,024)			32,348
Non-competition arrangements	5				940		(31)			909
Backlog and construction contracts	1	-	2		1,257		(678)			579
Total intangible assets					$	117,168	$	(75,523)		$	41,645

Goodwill and Intangible Assets (Tables)

6 Months Ended

Mar. 31, 2026

Intangible Asset, Goodwill and Other [Abstract]

Goodwill [Table Text Block]


	Communications		Residential		Infrastructure Solutions			Commercial & Industrial		Total
Goodwill at September 30, 2025	$	12,336	$	51,370	$	44,124		$	—	$	107,830
Acquisitions	—		—		21,360		(1)	—		21,360



Goodwill at March 31, 2026	$	12,336	$	51,370	$	65,484		$	—	$	129,190

Intangible Asset, Finite-Lived [Table Text Block]

Intangible assets consist of the following:


	Estimated Useful Lives (in Years)			March 31, 2026
					Gross Carrying Amount		Accumulated Amortization		Net
Trademarks/trade names	5	-	20		$	21,089	$	(9,653)		$	11,436
Technical library	20				400		(251)			149
Customer relationships	1	-	15		117,892		(72,193)			45,699
Non-competition arrangements	5				940		(125)			815
Backlog and construction contracts	1	-	2		1,257		(910)			347
Total intangible assets					$	141,578	$	(83,132)		$	58,446


	Estimated Useful Lives (in Years)			September 30, 2025
					Gross Carrying Amount		Accumulated Amortization		Net
Trademarks/trade names	5	-	20		$	16,199	$	(8,549)		$	7,650
Technical library	20				400		(241)			159
Customer relationships	1	-	15		98,372		(66,024)			32,348
Non-competition arrangements	5				940		(31)			909
Backlog and construction contracts	1	-	2		1,257		(678)			579
Total intangible assets					$	117,168	$	(75,523)		$	41,645

- Definition

Tabular disclosure of goodwill.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482573/350-20-50-2

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 350
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482573/350-20-50-1A

+ Details

Revenue Recognition

6 Months Ended

Mar. 31, 2026

Revenue Recognition and Deferred Revenue [Abstract]

Revenue from External Customers by Products and Services [Table Text Block]

3. REVENUE RECOGNITION

Contracts

Our revenue is derived from contracts with customers, and we determine the appropriate accounting treatment for each contract at its inception. Our contracts primarily relate to electrical and mechanical contracting services, technology infrastructure products and services, and electro-mechanical solutions for industrial operations. Revenue is earned based upon an agreed fixed price or actual costs incurred plus an agreed upon percentage.

We account for a contract when: (i) it has approval and commitment from both parties, (ii) the rights of the parties are identified, (iii) payment terms are identified, (iv) the contract has commercial substance, and (v) collectability of consideration is probable. We consider the start of a project to be when the above criteria have been met and we have written authorization from the customer to proceed.

Performance Obligations

A performance obligation is a promise in a contract to transfer a distinct good or service to the customer. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied.

We recognize revenue over time for the majority of the services we perform as (i) control continuously transfers to the customer as work progresses at a project location controlled by the customer and (ii) we have the right to bill the customer as costs are incurred. Within our Infrastructure Solutions Custom Engineered Solutions business, we often perform work inside our own facilities, where control does not continuously transfer to the customer as work progresses. In such cases, we evaluate whether the work performed creates an asset with alternative use to the Company and whether we have the right to bill the customer as costs are incurred. Such assessment involves an evaluation of contractual termination clauses. Where we are creating an asset with no alternative use and we have a contractual right to payment for work performed to date, we recognize revenue over time. If we do not have such a right, we recognize revenue upon completion of the contract, when control of the work transfers to the customer.

For arrangements where we recognize revenue over time, we generally use the percentage of completion method of accounting under which revenue recognized is measured principally by the costs incurred and accrued to date for each contract as a percentage of the estimated total cost for each contract at completion. Contract costs include all direct material, labor and indirect costs related to contract performance. Changes in job performance, job conditions, estimated contract costs and profitability and final contract settlements may result in revisions to costs and income, and the effects of these revisions are recognized in the period in which the revisions are determined. Provisions for estimated losses on uncompleted contracts are made in the period in which such losses are determined. This process requires updates to the estimate of total costs to complete the contract, and these updates may include subjective assessments and judgments. Revenue for arrangements whose durations are short in nature is recognized when the project is complete and billable to the customer under the right to invoice practical expedient.

Variable Consideration

The transaction price for our contracts may include variable consideration, which includes changes to transaction price for unapproved change orders, claims and incentives. Change orders, claims and incentives are generally not distinct from the existing contract due to the significant integration service provided in the context of the contract and are accounted for as a modification of the existing contract. We estimate variable consideration at either the expected probability weighted value or the most likely amount in a range of possible consideration amounts, utilizing estimation methods that best predict the amount of consideration to which we will be entitled (or will be incurred in the case of liquidated damages, if any). We include variable consideration in the estimated transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur or when the uncertainty associated with the variable consideration is resolved. Our estimates of variable consideration and determination of whether to include estimated amounts in transaction price are based largely on an assessment of our anticipated performance and all information (historical, current and forecasted) that is reasonably available to us. The effect of variable consideration on the transaction price of a performance obligation is recognized as an adjustment to revenue on a cumulative catch-up basis. To the extent unapproved change orders and claims reflected in transaction price (or accounted for as a reduction of the transaction price in the case of liquidated damages) are not resolved in our favor, or to the extent incentives reflected in transaction price are not earned, there could be reductions in, or reversals of, previously recognized revenue.

Disaggregation of Revenue

We disaggregate our revenue from contracts with customers by activity and contract type, as these categories reflect how the nature, amount, timing and uncertainty of our revenue and cash flows are affected by economic factors. Our consolidated revenue for the three and six months ended March 31, 2026 and 2025 was derived from the following activities. Certain prior period amounts have been reclassified to conform with the current period presentation, where applicable. See details in the following tables:


	Three Months Ended March 31,				Six Months Ended March 31,
	2026		2025			2026		2025
Communications	$	367,696	$	273,016		$	719,616	$	505,976
Residential
Single-family Electrical	134,202		160,065			271,181		329,282
Single-family Plumbing & HVAC	90,059		79,168			172,919		153,351
Multi-family and Other	63,355		78,733			127,560		155,304
Total Residential	287,616		317,966			571,660		637,937
Infrastructure Solutions
Industrial Services	40,687		29,178			64,878		47,846
Custom Engineered Solutions	151,761		88,442			267,745		177,899
Total Infrastructure Solutions	192,448		117,620			332,623		225,745
Commercial & Industrial	126,524		125,358			221,343		213,849
Total revenue	$	974,284	$	833,960		$	1,845,242	$	1,583,507


	Three Months Ended March 31, 2026
		Communications		Residential		Infrastructure Solutions		Commercial & Industrial		Total
Fixed-price		$	219,657	$	287,616	$	163,624	$	112,454	$	783,351
Time-and-material		148,039		—		28,824		14,070		190,933
Total revenue		$	367,696	$	287,616	$	192,448	$	126,524	$	974,284

	Three Months Ended March 31, 2025
		Communications		Residential		Infrastructure Solutions		Commercial & Industrial		Total
Fixed-price		$	202,412	$	317,966	$	106,477	$	107,516	$	734,371
Time-and-material		70,604		—		11,143		17,842		99,589
Total revenue		$	273,016	$	317,966	$	117,620	$	125,358	$	833,960

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-URI https://asc.fasb.org/1943274/2147479806/606-10-50-7

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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2026	Sep. 30, 2025
Statement of Financial Position [Abstract]
Cash and cash equivalents	$ 48,655	$ 127,171
Accounts receivable	656,573	552,158
Accounts and Other Receivables, Net, Current	117,380	99,930
Inventories	126,679	111,536
Costs and estimated earnings in excess of billings	100,850	69,229
Prepaid expenses and other current assets	29,796	20,870
Total current assets	1,294,791	1,085,481
Property and equipment, net	320,583	183,231
Goodwill	129,190	107,830
Intangible assets, net	58,446	41,645
Equity Method Investments	63,888	59,662
Deferred tax assets	14,477	16,055
Operating right of use assets	100,616	88,388
Other non-current assets	12,047	13,369
Total assets	1,994,038	1,595,661
Accounts payable and accrued expenses	511,486	456,646
Billings in excess of costs and estimated earnings	286,548	176,782
Short-Term Debt	35,000	0
Total current liabilities	833,034	633,428
Long-term debt	0	0
Operating long-term lease liabilities	72,376	61,967
Liability for Uncertainty in Income Taxes, Noncurrent	7,486	6,755
Other non-current liabilities	3,892	5,549
Total liabilities	916,788	707,699
Noncontrolling interest	$ 4,572	$ 4,007
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred stock, value	$ 0	$ 0
Common stock, value	220	220
Treasury stock, value	(139,933)	(127,751)
Additional paid-in capital	210,776	210,668
Retained earnings	1,001,615	800,818
Total stockholders' equity	1,072,678	883,955
Total liabilities and stockholders' equity	1,994,038	1,595,661
Marketable Securities, Current	213,983	104,587
Restricted Cash	$ 875	$ 0
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Shares Issued	0	0

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Income Statement [Abstract]
Revenues	$ 974,284	$ 833,960	$ 1,845,242	$ 1,583,507
Cost of services	719,497	625,091	1,370,440	1,196,611
Gross profit	254,787	208,869	474,802	386,896
Selling, general and administrative expenses	142,442	116,044	264,257	219,083
Contingent consideration	129	339	258	678
Loss (gain) on sale of assets	(39)	(209)	299	(179)
Operating income (loss)	112,255	92,695	209,988	167,314
Interest expense	(1,531)	(266)	(1,997)	(784)
Gain (Loss) on Investments	37,333	5,488	54,188	7,892
Other (income) expense, net	574	765	2,400	1,924
Provision for (benefit from) income taxes	(38,319)	(26,090)	(66,725)	(46,073)
Income (Loss) from Equity Method Investments			4,226	0
Net income (loss)	110,312	72,592	202,080	130,273
Net income attributable to noncontrolling interest	(403)	(1,940)	(732)	(3,318)
Net Income (Loss) Available to Common Stockholders, Basic	$ 109,909	$ 70,652	$ 201,348	$ 126,955
Earnings Per Share, Basic	$ 5.51	$ 3.54	$ 10.09	$ 6.30
Earnings Per Share, Diluted	$ 5.44	$ 3.50	$ 9.95	$ 6.22
Weighted Average Number of Shares Outstanding, Basic	19,926,397	19,969,618	19,906,511	19,979,896
Weighted Average Number of Shares Outstanding, Diluted	20,186,385	20,213,442	20,179,707	20,229,877
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	$ 148,631	$ 98,682	$ 264,579	$ 176,346

Operating Segments	6 Months Ended
Operating Segments	Mar. 31, 2026
Segment Reporting [Abstract]
Segment Reporting [Text Block]	6. OPERATING SEGMENTS We manage and measure performance of our business in four distinct operating segments: Communications, Residential, Infrastructure Solutions, and Commercial & Industrial. These segments are reflective of how the Company's chief operating decision maker (“CODM”) reviews operating results for the purpose of allocating resources and assessing performance. The CODM primarily uses “Operating income (loss)” for each operating segment to assess performance and decide how to allocate resources. Investment gains and losses and certain other corporate income and expense items are not considered in assessing the financial performance of operating businesses. In evaluating performance of the operating businesses, the CODM may compare actual income from operations for a segment to its forecast or prior year results. The Company’s CODM is its Chief Executive Officer. Transactions between segments, if any, are eliminated in consolidation. Our corporate office provides general and administrative services, as well as support services, to each of our four operating segments. Management allocates certain shared costs among segments for selling, general and administrative expenses and depreciation expense.

- Definition

The entire disclosure for segment reporting.

+ References

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-URI https://asc.fasb.org/280/tableOfContent

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26

+ Details

Debt

6 Months Ended

Mar. 31, 2026

Debt Disclosure [Abstract]

Debt Disclosure [Text Block]

4. DEBT

We are a party to the Fourth Amended and Restated Credit Agreement (the “Amended Credit Agreement”), which provides for a revolving line of credit of $300,000, with a maturity date of January 21, 2030.

Under the Amended Credit Agreement, the Company is subject to certain financial covenants including a maximum Consolidated Total Leverage Ratio (as defined in the Amended Credit Agreement) of 3.00 to 1.00 and a minimum Consolidated Interest Coverage Ratio (as defined in the Amended Credit Agreement) of 3.00 to 1.00. As of March 31, 2026, the Company was in compliance with the financial covenants under the Amended Credit Agreement.

At March 31, 2026 and September 30, 2025, we had outstanding borrowings under our revolving credit facility of $35,000 and zero, respectively. At March 31, 2026, we had $11,335 in outstanding letters of credit and $253,665 of availability under our revolving credit facility.

Amounts outstanding bear interest at a rate equal to either (1) the Base Rate (which is the greater of the Federal Funds Rate (as defined in the Amended Credit Agreement) and the Prime Rate (as defined in the Amended Credit Agreement)), (2) the Daily Simple SOFR (as defined in the Amended Credit Agreement) or (3) Term SOFR (as defined in the Amended Credit Agreement), plus, in each case, an interest rate margin, which is determined quarterly based on our Consolidated Total Leverage Ratio, in accordance with the following thresholds:

Pricing Level

Consolidated Total Leverage Ratio

Interest Margin applicable to Daily Simple SOFR/Term SOFR

Interest Margin applicable to Base Rate

Greater than or equal to 2.50 to 1.00

2.25 percentage points

1.25 percentage points

Greater than or equal to 1.75 to 1.00, but less than 2.50 to 1.00

2.00 percentage points

1.00 percentage points

III

Greater than or equal to 1.00 to 1.00, but less than 1.75 to 1.00

1.75 percentage points

0.75 percentage points

Less than 1.00 to 1.00

1.50 percentage points

0.50 percentage points

In addition, we are charged monthly in arrears an unused commitment fee of 0.25% to 0.35% per annum on any unused portion of the revolving credit facility based on the Company's Consolidated Total Leverage Ratio.

The Amended Credit Agreement restricts certain types of transactions when the Company’s Consolidated Total Leverage Ratio, after giving pro forma effect thereto, exceeds 2.75 to 1.00. The Amended Credit Agreement contains other customary affirmative and negative covenants as well as events of default.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2026
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025	Feb. 20, 2025	Jul. 31, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares Authorized	100,000,000		100,000,000		100,000,000
Treasury Stock Acquired, Average Cost Per Share		$ 172.80		$ 172.80
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			47,603	38,744
Share Repurchase Program, Authorized, Amount							$ 200,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant	1,299,355		1,299,355
Contingent consideration	$ 129	$ 339	$ 258	$ 678
Treasury Stock Acquired, Average Cost Per Share		$ 172.80		$ 172.80
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			47,603	38,744
Residential [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contingent consideration	0	$ 0	$ 0	$ 0
Infrastructure Solutions [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contingent consideration	129	339	258	678
Phantom Share Units (PSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	132	159	290	319
us-gaap_PhantomShareUnitsPSUsMember_Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 3,366	2,980	$ 6,935	$ 4,766
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period			15,680
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period			2,566
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period			(121,010)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number	198,859		198,859		306,755
Stock Issued During Period, Shares, Treasury Stock Reissued			121,139	94,752
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period			2,566
Common Stock, par value $0.01 per share
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 52	$ 0	$ 91	$ 0
Repurchase Agreements [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Treasury Stock, Shares, Acquired		118,314	4,112	118,314
Amended Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized						750,000

Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Revenue Recognition (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025	Sep. 30, 2025
Revenue Recognition and Deferred Revenue [Abstract]
Unbilled Receivables, Current	$ 22,344		$ 22,344
Costs and estimated earnings in excess of billings	100,850		100,850		$ 69,229
Billings in excess of costs and estimated earnings	(286,548)		(286,548)		$ (176,782)
Contract with Customer, Liability, Revenue Recognized			154,185	$ 140,390
Performance Obligation Next 12 Months	1,839,240		1,839,240
Revenue, Remaining Performance Obligation, Amount	2,347,101		2,347,101
Disaggregation of Revenue [Line Items]
Revenues	974,284	$ 833,960	1,845,242	1,583,507
Contract with Customer, Liability, Revenue Recognized			154,185	140,390
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance Obligation Next 12 Months	1,839,240		1,839,240
Revenue, Remaining Performance Obligation, Amount	2,347,101		2,347,101
Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues	126,524	125,358	221,343	213,849
Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	367,696	273,016	719,616	505,976
Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	192,448	117,620	332,623	225,745
Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	287,616	317,966	571,660	637,937
Fixed-price Contract [Member]
Disaggregation of Revenue [Line Items]
Revenues	783,351	734,371	1,506,190	1,397,065
Fixed-price Contract [Member] \| Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues	112,454	107,516	196,045	183,706
Fixed-price Contract [Member] \| Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	219,657	202,412	443,351	368,745
Fixed-price Contract [Member] \| Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	163,624	106,477	295,134	206,677
Fixed-price Contract [Member] \| Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	287,616	317,966	571,660	637,937
Time-and-materials Contract [Member]
Disaggregation of Revenue [Line Items]
Revenues	190,933	99,589	339,052	186,442
Time-and-materials Contract [Member] \| Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues	14,070	17,842	25,298	30,143
Time-and-materials Contract [Member] \| Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	148,039	70,604	276,265	137,231
Time-and-materials Contract [Member] \| Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	28,824	11,143	37,489	19,068
Time-and-materials Contract [Member] \| Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 0	0	$ 0	0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months		12 months
industrial Services [Member] \| Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 40,687	29,178	$ 64,878	47,846
Custom Power Solutions [Member] \| Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	151,761	88,442	267,745	177,899
Single Family Contracts [Member] \| Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	134,202	160,065	271,181	329,282
Multi Family and Other [Member] \| Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	63,355	78,733	127,560	155,304
Single Family Contracts Plumbing HVAC \| Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 90,059	$ 79,168	$ 172,919	$ 153,351

Controlling Shareholder	6 Months Ended
Controlling Shareholder	Mar. 31, 2026
Risks and Uncertainties [Abstract]
Controlling Shareholder [Text Block]	2. CONTROLLING STOCKHOLDER Tontine Associates, L.L.C. (“Tontine Associates”), together with its affiliates (collectively, “Tontine”), is the Company’s controlling stockholder, owning approximately 53 percent of the Company’s outstanding common stock based on a Form 4 filed by Tontine with the SEC on February 17, 2026 and the Company's shares outstanding as of April 27, 2026. Accordingly, Tontine has the ability to exercise significant control over our affairs, including the election of directors and most actions requiring the approval of stockholders. While Tontine is subject to certain restrictions under federal securities laws on sales of its shares as an affiliate, the Company has filed a resale shelf registration statement to register for resale a majority of the shares of IES common stock owned by Tontine. As long as the resale shelf registration statement remains effective and the Company remains eligible to use it, Tontine has the ability to resell any or all of its registered shares from time to time in one or more offerings, as described in the resale shelf registration statement and in any prospectus supplement filed in connection with an offering pursuant to the resale shelf registration statement. Should Tontine, or its underlying individual owners, sell or otherwise dispose of all or a significant portion of its position in IES, a change in control of IES could occur. A change of control would trigger the change of control provisions in a number of our material agreements, including our credit agreement, bonding agreements with our sureties and our executive severance plan. Jeffrey L. Gendell was appointed Executive Chairman of the Company effective July 1, 2025 after serving as Chief Executive Officer of the Company from October 1, 2020 to June 30, 2025, and as the Company's Interim Chief Executive Officer from July 31, 2020 to September 30, 2020. Mr. Gendell has also served as a director and as Chairman of the Board of Directors since November 2016. He is the managing member and founder of Tontine, and the brother of David B. Gendell, who has served as a member of our Board of Directors since February 2012, and who previously served as Interim Director of Operations from November 2017 to January 2019, as Vice Chairman of the Board from November 2016 to November 2017 and as Chairman of the Board from January 2015 to November 2016. David B. Gendell was an employee of Tontine from 2004 until January 2018. The Company is a party to a sublease agreement with Tontine Associates for corporate office space in Greenwich, Connecticut. On August 1, 2024, the Company entered into an amendment of the sublease agreement to extend the term of the agreement through September 30, 2025, effective September 1, 2024, while maintaining monthly payments due in the amount of approximately $9. On August 1, 2025, the Company entered into an amendment of the sublease agreement to extend the term of the agreement through September 30, 2026. Payments by the Company are at a rate consistent with that paid by Tontine Associates to its landlord. On December 6, 2018, the Company entered into a Board Observer Letter Agreement (the "Observer Agreement") with Tontine Associates in order to assist Tontine in managing its investment in the Company. Subject to the terms and conditions set forth in the Observer Agreement, the Company granted Tontine the right, at any time that Tontine holds at least 20% of the outstanding common stock of the Company, to appoint a representative to serve as an observer to the Board (the “Board Observer”). The Board Observer, who must be reasonably acceptable to those members of the Board who are not affiliates of Tontine, shall have no voting rights or other decision making authority. Subject to the terms and conditions set forth in the Observer Agreement, so long as Tontine has the right to appoint a Board Observer, the Board Observer will have the right to attend and participate in meetings of the Board and the committees thereof, subject to confidentiality requirements, and to receive reimbursement for reasonable out-of-pocket expenses incurred in his or her capacity as a Board Observer and such rights to coverage under the Company’s directors’ and officers’ liability insurance policy as are available to the Company’s directors.

Statement of Cash Flows, Supplemental Disclosures (Statement) - USD ($) $ in Thousands	Mar. 31, 2026	Sep. 30, 2025	Mar. 31, 2025	Sep. 30, 2024
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 49,530	$ 127,171	$ 22,427	$ 100,832
Restricted Cash	875	0
Cash and cash equivalents	$ 48,655	$ 127,171

- Definition

Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

+ References + Details

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Statement of Cash Flows [Abstract]
Net income (loss)	$ 202,080	$ 130,273
Bad debt expense	(102)	265
Deferred financing cost amortization	305	177
Depreciation and amortization	28,765	23,035
Gain (Loss) on Disposition of Property Plant Equipment	299	(179)
Non-cash compensation expense	7,316	5,085
Deferred income taxes	8,325	228
Unrealized Gain (Loss) on Investments	(34,621)	(7,829)
Business Combination, Achieved in Stages, Preacquisition Equity Interest in Acquiree, Remeasurement, Gain	(2,818)	0
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions	(4,226)	0
Increase (Decrease) in Debt Securities, Trading, and Equity Securities, FV-NI	(78,748)	(23,016)
Accounts receivable	(82,340)	(43,976)
Inventories	(13,019)	5,673
Costs and estimated earnings in excess of billings	(22,386)	(27,277)
Prepaid expenses and other current assets	(20,579)	(11,292)
Other non-current assets	(317)	(2,929)
Accounts payable and accrued expenses	35,547	8,628
Billings in excess of costs and estimated earnings	108,753	4,633
Other non-current liabilities	(1,247)	605
Net cash provided by operating activities	130,987	62,104
Capital expenditures	(78,407)	(30,122)
Proceeds from sale of assets	386	527
Payments to Acquire Businesses, Net of Cash Acquired	143,108	22,609
Net cash used in investing activities	(221,129)	(97,104)
Borrowings of debt	90,000	976,400
Repayments of debt	(55,000)	(976,400)
Cash paid for finance leases	(2,219)	(2,173)
Distribution to noncontrolling interest	(890)	(4,967)
Purchase of treasury stock	(19,390)	(36,265)
Net cash used in financing activities	12,501	(43,405)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(77,641)	(78,405)
CASH, CASH EQUIVALENTS, beginning of period	127,171	100,832
CASH, CASH EQUIVALENTS, end of period	49,530	22,427
Cash paid for interest	1,459	355
Cash paid for income taxes (net)	34,616	64,197
Payments to Acquire Investments	$ 0	$ (44,900)

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2026	Sep. 30, 2025
Statement of Financial Position [Abstract]
Accounts Receivable, Allowance for Credit Loss, Current	$ (4,894)	$ (4,340)
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	100,000,000	100,000,000
Common Stock, Shares, Issued	22,049,529	22,049,529
Common Stock, Shares, Outstanding	19,923,887	19,854,463
Treasury Stock, Shares	2,125,642	2,195,066

- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480100/505-10-S45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477657/942-210-S45-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478478/942-210-S50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(20))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.6-05(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479170/946-210-S99-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(4)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04(16)(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479170/946-210-S99-1

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(7))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3

+ Details

- Definition

The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References + Details

Stockholders' Equity (Tables)

6 Months Ended

Mar. 31, 2026

Equity [Abstract]

Share-Based Payment Arrangement, Cost by Plan

A summary of the compensation expense related to our stock awards recognized during the three and six months ended March 31, 2026 and 2025 is provided in the table below:


	Three Months Ended March 31,				Six Months Ended March 31,
	2026		2025		2026		2025

Director PSUs	$	132	$	159	$	290	$	319
Employee PSUs	$	3,366	$	2,980	$	6,935	$	4,766
Director common stock grants	$	52	$	—	$	91	$	—

Share-Based Payment Arrangement, Outstanding Award, Activity, Excluding Option

A summary of Employee PSU activity for the six months ended March 31, 2026 is provided in the table below:


Unvested at September 30, 2025			306,755
Granted			15,680
Vested			(121,010)
Forfeited			(2,566)
Unvested at March 31, 2026			198,859

Per Share Information (Tables)

6 Months Ended

Mar. 31, 2026

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

The following table reconciles the components of basic and diluted earnings per share for the three and six months ended March 31, 2026 and 2025:


	Three Months Ended March 31,				Six Months Ended March 31,
	2026		2025		2026		2025
Numerator:
Net income attributable to IES Holdings, Inc.	$	109,909	$	70,652	$	201,348	$	126,955
(Increase) decrease in noncontrolling interest	(138)		86		(551)		(1,058)

Net income attributable to common stockholders of IES Holdings, Inc.	$	109,771	$	70,738	$	200,797	$	125,897

Denominator:
Weighted average common shares outstanding — basic	19,926,397		19,969,618		19,906,511		19,979,896
Effect of dilutive non-vested securities	259,988		243,824		273,195		249,981
Weighted average common and common equivalent shares outstanding — diluted	20,186,385		20,213,442		20,179,707		20,229,877

Earnings per share attributable to common stockholders of IES Holdings, Inc.:
Basic	$	5.51	$	3.54	$	10.09	$	6.30
Diluted	$	5.44	$	3.50	$	9.95	$	6.22

Potentially dilutive securities excluded from the computation of diluted earnings per share as the effect of their inclusion would have been anti-dilutive:
Employee phantom stock units	69		16,635		1,347		33,179

Fair Value Measurements

6 Months Ended

Mar. 31, 2026

Fair Value Disclosures [Abstract]

Fair Value Disclosures [Text Block]

. FAIR VALUE MEASUREMENTS

Fair Value Measurement Accounting

Fair value is considered the price to sell an asset, or transfer a liability, between market participants on the measurement date. Fair value measurements assume that (1) the asset or liability is exchanged in an orderly manner, (2) the exchange is in the principal market for that asset or liability, and (3) the market participants are independent, knowledgeable, and able and willing to transact an exchange. Fair value accounting and reporting establishes a framework for measuring fair value by creating a hierarchy for observable independent market inputs and unobservable market assumptions and expands disclosures about fair value measurements. Judgment is required to interpret the market data used to develop fair value estimates. As such, the estimates presented herein are not necessarily indicative of the amounts that could be realized in a current exchange. The use of different market assumptions and/or estimation methods could have a material effect on the estimated fair value.

The carrying values of cash and cash equivalents, restricted cash, accounts receivable, accounts payable and contract assets and liabilities approximate fair values due to their short-term nature. The carrying value of borrowings under our revolving credit facility approximates fair value as its effective interest rate is variable and approximates market rates.

At March 31, 2026 and September 30, 2025, financial assets and liabilities measured at fair value on a recurring basis were limited to investments in marketable equity securities classified as trading securities, our executive savings plan, under which certain employees are permitted to defer a portion of their base salary and/or bonus for a Plan Year (as defined in the plan), and contingent consideration liabilities related to certain of our acquisitions.


	March 31, 2026
			Total Fair Value		Quoted Prices (Level 1)		Significant Unobservable Inputs (Level 3)
Equity securities		$	213,983	$	213,983	$	—


Executive savings plan assets			740		740		—
Executive savings plan liabilities			(609)		(609)		—
Contingent consideration liability			(2,371)		—		(2,371)
Total		$	211,743	$	214,114	$	(2,371)


	September 30, 2025
			Total Fair Value		Quoted Prices (Level 1)		Significant Unobservable Inputs (Level 3)
Equity securities		$	104,587	$	104,587	$	—

Executive savings plan assets			1,120		1,120		—

Executive savings plan liabilities			(984)		(984)		—

Contingent consideration liability			(2,113)		—		(2,113)
Total		$	102,610	$	104,723	$	(2,113)

On April 1, 2024, we entered into a contingent consideration arrangement in connection with the acquisition of Greiner Industries, Inc. The fair value of this liability, which is included in "Accounts payable and accrued expenses" in our Condensed Consolidated Balance Sheets, is measured on a recurring basis classified within Level 3 of the fair value hierarchy. Net adjustments to fair value of such liabilities are included in Contingent consideration in our Condensed Consolidated Statements of Comprehensive Income.

The table below presents the change in fair value of liabilities measured using significant unobservable inputs (Level 3).












	Contingent consideration liability
Fair value at September 30, 2025	$	(2,113)

Net adjustments to fair value included in “Contingent consideration”	(258)

Fair value at March 31, 2026	$	(2,371)

Investment in Debt and Equity Securities and Other Trading Assets [Text Block]

Investments in Marketable Securities


	March 31, 2026		September 30, 2025
Marketable equity securities	$	213,983	$	104,587


	Three Months Ended March 31,				Six Months Ended March 31,
	2026		2025		2026		2025
Unrealized gain on marketable equity securities	$	17,706	$	5,547	$	34,621	$	7,862
Unrealized loss on marketable debt securities	—		(66)		—		(33)

Total unrealized gain on marketable securities	$	17,706	$	5,481	$	34,621	$	7,829

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
-SubTopic 820
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Operating Segments (Tables)

6 Months Ended

Mar. 31, 2026

Segment Reporting [Abstract]

Segment Reporting [Table Text Block]

Segment information for the three and six months ended March 31, 2026 and 2025 is as follows:


		Three Months Ended March 31, 2026
		Communications		Residential		Infrastructure Solutions		Commercial & Industrial		Corporate		Total
Revenues		$	367,696	$	287,616	$	192,448	$	126,524	$	—	$	974,284
Cost of services		273,970		225,820		129,328		90,379		—		719,497
Gross profit		93,726		61,796		63,120		36,145		—		254,787
Selling, general and administrative		32,567		55,375		21,050		14,751		18,699		142,442

Contingent consideration		—		—		129		—		—		129
Gain on sale of assets		(1)		(3)		(2)		(33)		—		(39)
Operating income (loss)		$	61,160	$	6,424	$	41,943	$	21,427	$	(18,699)	$	112,255
Other data:
	Depreciation and amortization expense	$	1,836	$	6,363	$	6,482	$	1,059	$	351	$	16,091
	Capital expenditures	$	22,296	$	1,361	$	4,617	$	3,515	$	44	$	31,833
	Total assets	$	472,610	$	342,980	$	582,557	$	220,919	$	374,972	$	1,994,038


		Three Months Ended March 31, 2025
		Communications		Residential		Infrastructure Solutions		Commercial & Industrial		Corporate		Total
Revenues		$	273,016	$	317,966	$	117,620	$	125,358	$	—	$	833,960
Cost of services		209,973		238,294		78,319		98,505		—		625,091
Gross profit		63,043		79,672		39,301		26,853		—		208,869
Selling, general and administrative		23,441		57,151		12,487		11,024		11,941		116,044
Contingent consideration		—		—		339		—		—		339
Gain on sale of assets		(21)		(156)		(9)		(23)		—		(209)
Operating income (loss)		$	39,623	$	22,677	$	26,484	$	15,852	$	(11,941)	$	92,695
Other data:
	Depreciation and amortization expense	$	1,255	$	5,913	$	3,942	$	612	$	226	$	11,948
	Capital expenditures	$	6,372	$	3,748	$	2,999	$	2,149	$	1,685	$	16,953
	Total assets	$	343,356	$	379,510	$	328,027	$	121,990	$	191,676	$	1,364,559

- Definition

Tabular disclosure of segment reporting. Includes, but is not limited to, reconciliation of reportable segment amount to corresponding consolidated total.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-31

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-34

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
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-Section 50
-Paragraph 32
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-30

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26C

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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-Paragraph 26B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26B

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
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-Paragraph 26A
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-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26A

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org/1943274/2147482810/280-10-50-25

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
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-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-15

+ Details

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Parent	Treasury Stock, Common
Statement [Line Items]
Treasury Stock, Shares						2,077,859
Stockholders' Equity Attributable to Parent at Sep. 30, 2024	$ 611,113	$ 220	$ 203,458	$ 497,760		$ (90,325)
Shares, Issued at Sep. 30, 2024		22,049,529
Statement [Line Items]
Issuances under compensation plans	0		(4,218)			$ (4,218)
Issuances under compensation plans, shares						94,752
Acquisition of treasury stock	36,265		0			$ 36,265
Acquisition of treasury stock, shares						(178,106)
Non-cash compensation	(5,038)		(5,038)
Stockholders' Equity, Period Increase (Decrease)	1,058			1,058
Net income (loss)	130,273			126,955
Noncontrolling Interest, Change in Redemption Value	(1,401)
Stockholders' Equity Attributable to Parent at Mar. 31, 2025	705,783	$ 220	204,278	623,657		$ (122,372)
Shares, Issued at Mar. 31, 2025		22,049,529
Statement [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	126,955
Treasury Stock, Shares						2,042,899
Stockholders' Equity Attributable to Parent at Dec. 31, 2024	652,439	$ 220	201,138	552,919		$ (101,838)
Shares, Issued at Dec. 31, 2024		22,049,529
Statement [Line Items]
Acquisition of treasury stock	20,534		0			$ 20,534
Acquisition of treasury stock, shares						(118,314)
Non-cash compensation	(3,140)		(3,140)
Net income (loss)	72,592
Noncontrolling Interest, Change in Redemption Value				86	$ 86
Stockholders' Equity Attributable to Parent at Mar. 31, 2025	705,783	$ 220	204,278	623,657		$ (122,372)
Shares, Issued at Mar. 31, 2025		22,049,529
Statement [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	$ 70,652
Treasury Stock, Shares						2,161,213
Treasury Stock, Shares	2,195,066					2,195,066
Stockholders' Equity Attributable to Parent at Sep. 30, 2025	$ 883,955	$ 220	210,668	800,818		$ (127,751)
Shares, Issued at Sep. 30, 2025		22,049,529
Statement [Line Items]
Issuances under compensation plans	0		(7,208)			$ (7,208)
Issuances under compensation plans, shares						121,139
Acquisition of treasury stock	19,390		0			$ 19,390
Acquisition of treasury stock, shares						(51,715)
Non-cash compensation	(7,316)		(7,316)
Stockholders' Equity, Period Increase (Decrease)	551			551
Net income (loss)	202,080			201,348
Noncontrolling Interest, Change in Redemption Value	(723)
Stockholders' Equity Attributable to Parent at Mar. 31, 2026	1,072,678	$ 220	210,776	1,001,615		$ (139,933)
Shares, Issued at Mar. 31, 2026		22,049,529
Statement [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	201,348
Treasury Stock, Shares						2,122,036
Stockholders' Equity Attributable to Parent at Dec. 31, 2025	961,077	$ 220	207,412	891,844		$ (138,399)
Shares, Issued at Dec. 31, 2025		22,049,529
Statement [Line Items]
Issuances under compensation plans	0		(186)			$ (186)
Issuances under compensation plans, shares						506
Acquisition of treasury stock	1,720		0			$ 1,720
Acquisition of treasury stock, shares						(4,112)
Non-cash compensation	(3,550)		(3,550)
Net income (loss)	110,312
Noncontrolling Interest, Change in Redemption Value				(138)	$ (138)
Stockholders' Equity Attributable to Parent at Mar. 31, 2026	1,072,678	$ 220	$ 210,776	$ 1,001,615		$ (139,933)
Shares, Issued at Mar. 31, 2026		22,049,529
Statement [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	$ 109,909
Treasury Stock, Shares	2,125,642					2,125,642

Controlling Shareholder (Details) - USD ($) $ in Thousands	Mar. 01, 2023	Mar. 31, 2026
Risks and Uncertainties [Abstract]
ControllingShareholderOwnershipPercentage		53.00%
Related Party Transaction, Purchases from Related Party	$ 9

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Mar. 31, 2026
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	12. COMMITMENTS AND CONTINGENCIES Legal Matters From time to time, we are a party to various claims, lawsuits and other legal proceedings that arise in the ordinary course of business. We maintain various insurance coverages to minimize financial risk associated with these proceedings. None of these proceedings, separately or in the aggregate, are expected to have a material adverse effect on our financial position, results of operations or cash flows. With respect to all such proceedings, we record reserves when it is probable that a liability has been incurred and the amount of loss can be reasonably estimated. We expense routine legal costs related to these proceedings as they are incurred. In the course of performing work as a subcontractor, from time to time we may be involved in projects which are the subject of contractual disputes between the general contractor and project owner, or between us and the general contractor. In such cases, payment of amounts owed to us by the general contractor may be delayed as contractual disputes are resolved through mediation, arbitration, or litigation. Such disputes may cause us to incur legal fees and other expenses to enforce our contractual rights, and we may not prevail in recovering all amounts to which we believe we are contractually entitled. Risk Management We retain the risk for workers’ compensation, employer’s liability, automobile liability, construction defects, general liability and employee group health claims, as well as pollution coverage, resulting from uninsured deductibles per accident or occurrence which are generally subject to annual aggregate limits. Our general liability program provides coverage for bodily injury and property damage. In many cases, we insure third parties, including general contractors, as additional insured parties under our insurance policies. Losses are accrued based upon our known claims incurred and an estimate of claims incurred but not reported. As a result, many of our claims are effectively self-insured. Many claims against our insurance are in the form of litigation. At March 31, 2026 and September 30, 2025, we had $13,544 and $12,131, respectively, accrued for self-insurance liabilities. Because the reserves are based on judgment and estimates and involve variables that are inherently uncertain, such as the outcome of litigation and an assessment of insurance coverage, there can be no assurance that the ultimate liability will not be higher or lower than such estimates. Some of the underwriters of our casualty insurance program require us to post letters of credit as collateral. This is common in the insurance industry. To date, we have not had a situation where an underwriter has had reasonable cause to effect payment under a letter of credit. At March 31, 2026 and September 30, 2025, $11,335 and $5,545, respectively, of our outstanding letters of credit was utilized to collateralize our insurance program. Surety As of March 31, 2026, the estimated cost to complete our bonded projects was approximately $312,385. We evaluate our bonding requirements on a regular basis, including the terms offered by our sureties. We believe the bonding capacity presently provided by our current sureties is adequate for our current operations and will be adequate for our operations for the foreseeable future. Other Commitments and Contingencies Some of our customers and vendors require us to post letters of credit, or provide intercompany guarantees, as a means of guaranteeing performance under our contracts and ensuring payment by us to subcontractors and vendors. If our customer has reasonable cause to effect payment under a letter of credit, we would be required to reimburse our creditor for the letter of credit. From time to time, we may enter into firm purchase commitments for materials, such as copper or aluminum wire, which we expect to use in the ordinary course of business. These commitments are typically for terms of less than one year and require us to buy minimum quantities of materials at specific intervals at a fixed price over the term. As of March 31, 2026, we had firm commitments of $15,773 o