Business (Details) - USD ($) $ in Thousands	9 Months Ended
Business (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Jun. 30, 2025	Sep. 30, 2025	Sep. 30, 2024
Accounting Policies [Abstract]
Redeemable Noncontrolling Interest, Equity, Redemption Value	$ 5,271
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. We will present the required disclosures in our annual report with no impact on 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 disclosures; however, it will not impact our financial condition, results of operations, or cash flows. In September 2025, the FASB issued Accounting Standard Update No. 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software (“ASU 2025-06”). This standard amends the existing standard for capitalizing costs to develop or obtain software for internal use. This update removes the requirement for costs associated with internal-use software projects to be capitalized only at certain stages of development, instead only requiring that management has authorized and committed to funding a software project and that it is probable that the project will be completed and the software will be used for the function intended in order for these costs to be capitalized. This update is effective for fiscal years beginning after December 15, 2027, and interim periods within fiscal years beginning after December 15, 2028. Early adoption is permitted. This update may be applied on a prospective or retrospective basis, or a modified prospective basis for in-process projects. We are evaluating the impact this update will have on our financial condition, results of operations, and cash flows.
Redeemable Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest	$ 1,304	$ 5,375
Payments to Noncontrolling Interests	(889)	(7,536)
Noncontrolling Interest, Change in Redemption Value	849	2,142
Redeemable Noncontrolling Interest, Equity, Carrying Amount	5,271	$ 40,977	$ 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%

IES Holdings, Inc. 10-Q