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[Member] The Bowers Group, Inc. 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Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Interest paid, net of interest rate swaps Interest Paid, Excluding Capitalized Interest, Operating Activity Statement of Cash Flows [Abstract] Hedging Designation [Axis] Hedging Designation [Axis] Schedule of Ownership of Legence Holdings Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table Text Block] Credit Facility [Axis] Credit Facility [Axis] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Self insurance coverage Self Insurance, Threshold For Stop-Loss Insurance Self Insurance, Threshold For Stop-Loss Insurance Long-term debt, net of current portion (including $97,162 and $84,735 as of June 30, 2026 and December 31, 2025, respectively, from related parties) Long-term debt, net of current portion Long-Term Debt and Lease Obligation Thereafter Finite Lived Intangible Assets Amortization Expense After Year Four Finite 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revenue Cost of Product and Service Sold Award Timing Method Award Timing Method [Text Block] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Variable rate floor (as percent) Debt Instrument, Variable Rate Floor Debt Instrument, Variable Rate Floor Increase in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Notes payable, noncurrent Notes Payable, Noncurrent Incremental Term Loan Incremental Term Loan [Member] Incremental Term Loan Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Deferred offering costs included in Accrued and other current liabilities Deferred Offering Costs Included In Accrued And Other Current Liabilities Deferred Offering Costs Included In Accrued And Other Current Liabilities Reasonable possible losses in excess of reserves established Loss Contingency, Accrual, Current 3.3750% Interest Rate Swap, Maturing at December 2026 3.3750% Interest Rate Swap, Maturing at December 2026 [Member] 3.3750% Interest Rate Swap, Maturing at December 2026 Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Net loss attributable to Legence Net Income (Loss) Attributable to Parent Long-Term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Proceeds from sale of property and equipment Proceeds from Sale of Property, Plant, and Equipment Location, Statement of Financial Position, Balance [Axis] Location, Statement of Financial Position, Balance [Axis] Statement [Table] Statement [Table] Restatement Determination Date: Restatement Determination Date [Axis] Interest income Investment Income, Interest Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative Instruments and Hedging Activities Disclosures [Line Items] Fed Funds Effective Rate Overnight Index Swap Rate Fed Funds Effective Rate Overnight Index Swap Rate [Member] 4.0433% Interest Rate Swap, Maturing January 31,2024 to September 14, 2025 4.0433% Interest Rate Swap, Maturing January 31,2024 to September 14, 2025 [Member] 4.0433% Interest Rate Swap, Maturing January 31,2024 to September 14, 2025 Maintenance & Service Maintenance And Service [Member] Maintenance And Service Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] LGN A Units LGN A Units [Member] LGN A Units Revenue: Revenues [Abstract] Accrued and other current liabilities Business Combination, Recognized Liability Assumed, Liability, Accrued And Other Liabilities, Current Business Combination, Recognized Liability Assumed, Liability, Accrued And Other Liabilities, Current Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Effect of assumed exchange of LGN B Units Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities Numerator—diluted: Net Income (Loss) Available to Common Stockholders, Diluted [Abstract] Prepaid expenses and other current assets Business Combination, Recognized Asset Acquired, Prepaid Expense and Other Asset, Current Derivative Instruments and Hedging Activities Disclosure [Abstract]