Accrued Liabilities and Deferred Revenues, Current Accrued expenses and other current liabilities Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Also includes the carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income. Legal Reserve Legal reserve Amount of the current period expense charged against operations for estimate of the probable outcome of potential and pending litigation. Excludes statutory reserves for a bank or insurance company. Interest Expense and Amortization of Deferred Charges Interest expense The cost of borrowed funds accounted for as interest that was charged against earnings during the period and the amount of amortization of deferred charges applied against earnings during the period. Increase (Decrease) in Other Accrued Liabilities and Deferred Liabilities Accrued expenses and other current liabilities The increase (decrease) during the reporting period in other expenses incurred but not yet paid and the change during the period in carrying value for all deferred liabilities due within one year or operating cycle. Payments to Acquire Intangible Assets and Software Purchase of intangible assets The cash outflow to acquire assets without physical form usually arising from contractual or other legal rights, excluding goodwill. In addition, the cash outflow associated with the development, modification or acquisition of software programs or applications for internal use (that is, not to be sold, leased or otherwise marketed to others) that qualify for capitalization. Accrued Liabilities and Deferred Revenues Disclosure [Text Block] Accrued Expenses and Other Current Liabilities The entire disclosure for accrued liabilities and deferred revenues at the end of the reporting period. Document and Entity Information Consolidated Balance Sheets Statement [Table] Statement, Scenario [Axis] Scenario, Unspecified [Domain] Statement Statement [Line Items] ASSETS Assets [Abstract] Current Assets Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Beginning of period End of period Inventories, net Inventory, Net Deferred income taxes Deferred Tax Assets, Net, Current Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Total current assets Assets, Current Receivables, Net, Current Accounts receivable, net Property, plant and equipment, net Property, Plant and Equipment, Net. Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Goodwill Goodwill Other assets Other Assets, Noncurrent Total assets Assets LIABILITIES, PREFERRED STOCK AND EQUITY Liabilities and Equity [Abstract] Current Liabilities Liabilities, Current [Abstract] Current portion of long-term debt Long-term Debt, Current Maturities Current portion of capital lease obligations Capital Lease Obligations, Current Accounts Payable, Current Accounts payable Liabilities, Current Total current liabilities Accrued Income Taxes, Current Income taxes payable Long-term Debt, Excluding Current Maturities Long-term debt, net of current portion Capital Lease Obligations, Noncurrent Obligations under capital leases, net of current portion Deferred Tax Liabilities, Noncurrent Deferred income taxes Liabilities Total liabilities Commitments and contingencies Commitments and Contingencies. Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Common Stock, Value, Issued Common stock, $0.01 par value, 200,000,000 shares authorized, 27,712,038 and 27,667,122 shares issued and outstanding as of August 31, 2011 and May 31, 2011, respectively Retained Earnings (Accumulated Deficit). Accumulated deficit Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income (loss) Total Mistras Group, Inc. stockholders' equity Stockholders' Equity Attributable to Parent Noncontrolling interest Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Balance Balance Additional Paid in Capital Additional paid-in capital Total liabilities, preferred stock and equity Liabilities and Equity Other Liabilities, Noncurrent Other long-term liabilities Preferred Stock, Value, Issued Preferred stock, 10,000,000 shares authorized Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Preferred Stock, Shares Authorized Preferred stock, shares authorized Revenues: Revenues [Abstract] Sales Revenue, Services, Net Services Products Sales Revenue, Goods, Net Cost of revenues: Cost of Revenue [Abstract] Cost of Services Cost of services Cost of Goods Sold Cost of products sold Cost of Services, Depreciation Depreciation related to services Cost of Goods Sold, Depreciation Depreciation related to products Gross Profit Gross profit Selling, General and Administrative Expense Selling, general and administrative expenses Research and Development Expense Research and engineering Operating Income (Loss) Income from operations Other expenses Nonoperating Income (Expense) [Abstract] Gains (Losses) on Extinguishment of Debt Loss on extinguishment of long-term debt Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Income before provision for income taxes Income Tax Expense (Benefit) Provision for income taxes Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Net income Net Income (Loss) Attributable to Noncontrolling Interest Net loss attributable to noncontrolling interests, net of taxes Noncontrolling interest Net Income (Loss) Attributable to Parent Net income attributable to Mistras Group, Inc. Net income attributable to Mistras Group, Inc. Net Income (Loss) Available to Common Stockholders, Basic Net income attributable to common shareholders Earnings per Share Earnings per common share (see Note 4): Weighted average common shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted Average Number of Shares Outstanding, Basic Basic (in shares) Weighted Average Number of Shares Outstanding, Diluted Diluted (in shares) Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Preferred Stock, Accretion of Redemption Discount Accretion of preferred stock Consolidated Statements of Operations Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities Depreciation, Depletion and Amortization Depreciation and amortization Deferred Income Tax Expense (Benefit) Deferred income taxes Provision for Doubtful Accounts Provision for doubtful accounts Gain (Loss) on Disposition of Assets Gain on sale of assets Amortization of Financing Costs Amortization of deferred financing costs Share-based Compensation Stock compensation expense Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities, net of effect of acquisitions of businesses Accounts receivable Increase (Decrease) in Accounts Receivable Inventories Increase (Decrease) in Inventories Other assets Increase (Decrease) in Other Operating Assets Accounts payable Increase (Decrease) in Accounts Payable, Trade Income taxes payable Increase (Decrease) in Income Taxes Payable Increase (Decrease) in Prepaid Expense and Other Assets Prepaid expenses and other current assets Unrealized Gain (Loss) on Derivatives Interest rate swap Excess Tax Benefit from Share-based Compensation, Financing Activities Excess tax benefit from stock compensation Foreign Currency Transaction Gain (Loss), Realized Foreign currency loss (gain) Purchase of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Acquisition of businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Proceeds from sale of equipment Proceeds from Sale of Property, Plant, and Equipment Repayments of Long-term Debt Repayment of long-term debt Proceeds from Issuance of Long-term Debt Proceeds from borrowings of long-term debt Payments of Debt Issuance Costs Debt issuance costs Proceeds from Issuance of Common Stock Net proceeds from issuance of common stock Proceeds from Stock Options Exercised Proceeds from the exercise of stock options Proceeds from (Repayments of) Lines of Credit Net repayments against revolver Repayments of Long-term Capital Lease Obligations Repayment of capital lease obligations Cash and Cash Equivalents, Period Increase (Decrease) Net change in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) [Abstract] Cash and cash equivalents Supplemental Cash Flow Information [Abstract] Supplemental disclosure of cash paid Interest Paid Interest Income Taxes Paid Income taxes Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Noncash investing and financing Capital Lease Obligations Incurred Equipment acquired through capital lease obligations Notes Issued Issuance of notes payable and other debt obligations primarily related to acquisitions Consolidated Statements of Cash Flows Description of Business & Basis of Presentation Description of Business & Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Summary of Significant Accounting Policies Capitalization Capitalization Stockholders' Equity Note Disclosure [Text Block] Earnings per Share Earnings Per Share [Text Block] Acquisitions Acquisitions Business Combination Disclosure [Text Block] Property, Plant and Equipment, net Property, Plant and Equipment, net Property, Plant and Equipment Disclosure [Text Block] Accounts Receivable Accounts Receivable Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Inventories Inventories Inventory Disclosure [Text Block] Accrued Expenses and Other Current Liabilities Long-Term Debt Long-Term Debt Long-term Debt [Text Block]