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Aggregate intrinsic value exercisable at June 30, 2020 Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Houston Interests, LLC [Member] Houston Interests, LLC [Member] Houston Interests, LLC [Member] Contract Receivable Retainage, after Next Twelve Months Construction Contractor, Receivable, Retainage, after Year One SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract] Entity Current Reporting Status Entity Current Reporting Status Summary of long lived assets according to geographic areas Schedule Of Segment Reporting Information By Geographic Areas [Abstract] Schedule of segment reporting information by geographic areas. 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Gain on disposal of business (Note 3) Gain (Loss) on Disposition of Business Gain (Loss) on Disposition of Business Customer based [Member] Customer Based [Member] Customer based member. Stockholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Stock option activity and related information Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Net operating loss benefit and credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards June 30, 2025 Finite-Lived Intangible Asset, Expected Amortization, Year Five Document Fiscal Period Focus Document Fiscal Period Focus Goodwill and other intangible asset impairment Goodwill and Intangible Asset Impairment (Note 4) Goodwill and Intangible Asset Impairment Electrical Infrastructure [Member] Electrical Infrastructure [Member] Electrical Infrastructure [Member] Electrical infrastructure. Treasury shares repurchased to satisfy tax withholding obligations Other Treasury Share Purchases Other treasury share purchases. SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Table] Disclosure Customer Contracts Additional Information [Abstract] Disclosure Customer Contracts Additional Information [Abstract] Disclosure - Customer Contracts - Additional Information [Abstract] Other cash flow information: Supplemental Cash Flow Information [Abstract] Supplemental Cash Flow Information [Abstract] Company's portion of joint venture equity acquired mtrx_ControllingInterestOfJointVenture,Value mtrx_MatrixShareOfJointVenture,Value Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Employee Stock Purchase Plans, shares Shares issued under ESPP Stock Issued During Period, Shares, Employee Stock Purchase Plans Entity Filer Category Entity Filer Category Common Stock Common Stock [Member] Product and Service [Domain] Product and Service [Domain] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] SEC Schedule, 12-09, Allowance, Credit Loss [Member] SEC Schedule, 12-09, Allowance, Credit Loss [Member] Contribution made by company Defined Contribution Plan, Cost Customer Ten Customer Ten [Member] Customer Ten [Member] Components of the provision for income taxes Income Tax Expense (Benefit), Continuing Operations [Abstract] Employee Stock Purchase Plan, Termination Date Employee Stock Purchase Plan, Termination Date Employee Stock Purchase Plan, Termination Date Availability under the senior secured revolving credit facility Line of Credit Facility, Remaining Borrowing Capacity Class of Treasury Stock [Table] Class of Treasury Stock [Table] Disaggregation of Revenue [Abstract] Disaggregation of Revenue [Abstract] Finite-Lived Intangible Assets, Gross Gross carrying amount Finite-Lived Intangible Assets, Gross Provision for uncollectible accounts Accounts Receivable, Credit Loss Expense (Reversal) Letters of credit Letters Of Credit Issued Letters of credit issued, excluding insurance-related letters of credit. 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Stock Options [Member] Share-based Payment Arrangement, Option [Member] Reconciliation between the expected income tax provision applying the domestic federal statutory tax rate and the reported income tax provision Effective Income Tax Rate Reconciliation, Amount [Abstract] Organization and Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Equity, Class of Treasury Stock [Line Items] Equity, Class of Treasury Stock [Line Items] Basic (in shares) Weighted average shares outstanding Weighted Average Number of Shares Outstanding, Basic Risk-free interest rate Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Treasury stock, shares Treasury Stock, Shares Foreign currency translation loss (net of tax expense (benefit) of ($88), $27 and ($24) for the fiscal years ended June 30, 2020, 2019 and 2018, respectively) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax State Deferred State and Local Income Tax Expense (Benefit) OhioCarpentersPensionFundLocal1090and351 OhioCarpentersPensionFundLocal1090and351 [Member] OhioCarpentersPensionFundLocal1090and351 Plan Name [Domain] Plan Name [Domain] Domestic Income (Loss) from Continuing Operations before Income Taxes, Domestic Debt (Textual) [Abstract] Debt (Textual) [Abstract] Debt. Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Ownership interest in joint venture, percent Equity Method Investment, Ownership Percentage Revenue from Contract with Customer [Text Block] Revenue from Contract with Customer [Text Block] Cash paid during the period for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Tax Period [Domain] Tax Period [Domain] Total stockholders' equity Balances, beginning Balances, ending Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Right-of-Use asset obtained in exchange for operating lease liability Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Carrying value of other intangible assets Schedule Of Intangible Assets Excluding Goodwill Table [Table Text Block] Schedule of intangible assets excluding goodwill. Additional paid-in capital Additional Paid in Capital Director Awards [Member] Director Awards [Member] Director Awards [Member] June 30, 2021 Finite-Lived Intangible Asset, Expected Amortization, Year One Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Revenue Revenues Class of Stock [Axis] Class of Stock [Axis] Line Of Credit Basis Spread On Canadian Prime Rate Minimum Line Of Credit Basis Spread On Canadian Prime Rate Minimum Line of credit basis spread on Canadian prime rate minimum. Inventories Inventory, Policy [Policy Text Block] Provision (benefit) for federal, state and foreign income taxes Provision (benefit) for federal, state and foreign income taxes Income Tax Expense (Benefit) Cash paid during the period for income taxes Income Taxes Paid, Net Proceeds from disposal of business (Note 3) Proceeds from Divestiture of Businesses Proceeds from Divestiture of Businesses Tax Credit Carryforward, Description Tax Credit Carryforward, Description Baillie Tank Equipment, Ltd. [Member] Baillie Tank Equipment, Ltd. [Member] Baillie Tank Equipment, Ltd. 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Line Two Other assets and liabilities Increase (Decrease) in Other Operating Assets Entity Emerging Growth Company Entity Emerging Growth Company Valuation and Qualifying Accounts SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Total Deferred Income Tax Expense (Benefit) Finite-lived Intangible Assets, Fair Value Disclosure Finite-lived Intangible Assets, Fair Value Disclosure Total contributions made Multiemployer Plan, Employer Contribution, Cost Northwestern Ohio Plumbers and Pipe Fitters Local 50 [Member] Northwestern Ohio Plumbers and Pipe Fitters Local 50 [Member] Northwestern Ohio Plumbers and Pipe Fitters Local 50 Multiemployer Plans [Line Items] Multiemployer Plan [Line Items] Senior secured revolving credit facility Line of Credit Facility, Maximum 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shares repurchased to satisfy tax withholding obligations Other Treasury Shares Acquired Other treasury shares acquired. Construction Equipment [Member] Equipment [Member] Current liabilities: Liabilities, Current [Abstract] Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Entity Shell Company Entity Shell Company Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Common stock shares withheld Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Weighted average exercise price vested or expected to vest at June 30, 2020 Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price Average grant date fair value Share Based Compensation Arrangement By Share Based Payment Award Deferred Weighted Average Grant Date Fair Value Share based compensation arrangement by share based payment award deferred weighted average grant date fair value. Weighted average exercise price cancelled Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Remeasurement of deferred taxes Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount Recently Issued Accounting Standards New Accounting Pronouncements, Policy [Policy Text Block] Entity Public Float Entity Public Float Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Basic EPS: Earnings Per Share, Basic [Abstract]