Description of Business and Basis of Presentation (Policies)	9 Months Ended
Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Unaudited Condensed Consolidated Financial Statements contained in this report have been prepared in conformity with U.S. generally accepted accounting principles ("GAAP") and Securities and Exchange Commission ("SEC") guidance allowing for reduced disclosure for interim periods. In the opinion of management, the Unaudited Condensed Consolidated Financial Statements include all adjustments, which are of a normal recurring nature, necessary for a fair statement of the results for the interim periods of the years ending December 31, 2023 and December 31, 2022. Certain items included in these statements are based on management’s estimates. Actual results may differ from those estimates. The results of operations for any interim period are not necessarily indicative of the results expected for the year. The accompanying Unaudited Condensed Consolidated Financial Statements should be read in conjunction with the notes to the Audited Consolidated Financial Statements contained in the Company’s 2022 Annual Report on Form 10-K ("2022 Annual Report").
Principles of Consolidation	Principles of Consolidation The accompanying Unaudited Condensed Consolidated Financial Statements include the accounts of Mistras Group, Inc. as well as its wholly-owned subsidiaries, majority-owned subsidiaries and consolidated variable interest entities (VIE). For subsidiaries in which the Company’s ownership interest is less than 100%, the non-controlling interests are reported in stockholders’ equity in the accompanying Condensed Consolidated Balance Sheets. The non-controlling interests in net results, net of tax, is classified separately in the accompanying Unaudited Condensed Consolidated Statements of Income (Loss). All significant intercompany accounts and transactions have been eliminated in consolidation. The results of operations of companies acquired are included from the date of acquisition.
Reclassification	Reclassification Certain amounts in prior periods have been reclassified to conform to the current year presentation. Such reclassifications did not have a material effect on the Company’s financial condition or results of operations as previously reported.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. We recognize deferred tax assets and liabilities at enacted income tax rates for the temporary differences between the financial reporting bases and the tax bases of our assets and liabilities. Any effects of changes in income tax rates or tax laws are included in the provision for income taxes in the period of enactment. Our net deferred tax assets primarily consist of net operating loss carryforwards, or NOLs. A valuation allowance is provided if it is more likely than not that some or all of a deferred income tax asset will not be realized. A current tax liability or asset is recognized for the estimated taxes payable or refundable on tax returns for the current and prior years. As of September 30, 2023, management concluded that it is more likely than not that a substantial portion of the Company’s deferred tax assets will be realized. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate resolution. The Company’s effective income tax rate was approximately (16.8)% and 31.1% for the three months ended September 30, 2023 and 2022, respectively. The Company’s effective income tax rate was approximately (1.6)% and 48.5% for the nine months ended September 30, 2023 and 2022, respectively. The effective income tax rate for the three months ended September 30, 2023 was lower than the statutory rate primarily due to the impact of permanent tax adjustments related to executive compensation and goodwill impairments. The effective income tax rate for the three months ended September 30, 2022 was higher than the statutory rate primarily due to various permanent tax adjustments and a $0.1 million valuation allowance recorded on a foreign jurisdiction. The effective income tax rate for the nine months ended September 30, 2023 was lower than the statutory rate primarily due to the impact of permanent tax adjustments related to executive compensation and goodwill impairments. The effective income tax rate for the nine months ended September 30, 2022 was higher than the statutory rate due primarily to various permanent tax adjustments and a $0.9 million valuation allowance recorded during the period which was related to a foreign jurisdiction.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In March 2020 and updated in January 2021, the FASB issued Accounting Standards Update ("ASU") 2020-04 and 2021-01, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The amendments provide optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. The guidance provides optional expedients and exceptions for applying U.S. GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another rate that is expected to be discontinued. The amendments in ASU 2020-04 are effective for all entities as of March 12, 2020 through December 31, 2024. The Company is currently evaluating applicable contracts and the available expedients provided by the new guidance.
Revenue	RevenueThe Company derives the majority of its revenue by providing services on a time and material basis, and are short-term in nature. The Company accounts for revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers. Performance Obligations The Company provides highly integrated and bundled inspection services to its customers. The majority of the Company’s contracts have a single performance obligation as the promise to transfer the individual goods or services is not separately identifiable from other promises in the contracts and is, therefore, not distinct. For contracts with multiple performance obligations, the Company allocates the contract’s transaction price to each performance obligation using the Company’s best estimate of the standalone selling price of each distinct good or service in the contract. The primary method used to estimate standalone selling price is a relative selling price based on price lists. Contract modifications are not routine in the performance of the Company’s contracts. Generally, when contracts are modified, the modification is to account for changes in scope to the goods and services that are provided. In most instances, contract modifications are for goods or services that are distinct, and, therefore, are accounted for as a separate contract. The Company’s performance obligations are satisfied over time as work progresses or at a point in time. The majority of the Company’s revenue is recognized over time as work progresses for the Company’s service deliverables, which includes providing testing, inspection and mechanical services to our customers. Revenue is recognized over time, based on time and material incurred to date which best portrays the transfer of control to the customer. The Company also utilizes an available practical expedient that provides for revenue to be recognized in an amount that corresponds directly with the value to the customer of the entity’s performance completed to date. Fixed fee arrangements are determined based on expected labor, material, and overhead to be consumed on fulfillment of such services. For these arrangements, revenue is recognized on a cost-to-cost method tracked on an input basis. The majority of our revenue recognized at a point in time is related to product sales when the customer obtains control of the asset, which is generally upon shipment to the customer. Contract costs include labor, material and overhead. The Company expects any significant remaining performance obligations to be satisfied within one year. Contract Estimates The majority of the Company's revenues are short-term in nature. The Company enters into master service agreements ("MSAs") with customers that specify an overall framework and contract terms. The actual contracting to provide services or furnish products are triggered by a work order, purchase order, or some similar document issued pursuant to a MSA which sets forth the scope of services and/or identifies the products to be provided. From time-to-time, the Company may enter into longer-term contracts, which can range from several months to several years. Revenue on certain contracts is recognized as work is performed based on total costs incurred to date in relation to the total estimated costs for the performance of the contract at completion. This includes contract estimates of costs to be incurred for the performance of the contract. Cost estimation is based upon the professional knowledge and experience of the Company's project managers, engineers and financial professionals. Factors that are considered in estimating the work to be completed include the availability of materials, the effect of any delays in the Company's project performance and the recoverability of any claims. Whenever revisions of estimates, contract costs and/or contract values indicate that the contract costs will exceed estimated revenues, thus creating a loss, a provision for the total estimated loss is recorded in that period. Contract Balances The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits (contract liabilities) on the Consolidated Balance Sheets. Amounts are generally billed as work progresses in accordance with agreed-upon contractual terms, generally at periodic intervals (e.g., weekly, bi-weekly or monthly). Generally, billing occurs subsequent to revenue recognition, resulting in contract assets. However, the Company sometimes receives advances or deposits from its customers before revenue is recognized, resulting in contract liabilities. These assets and liabilities are aggregated on an individual contract basis and reported on the Consolidated Balance Sheets at the end of each reporting period within accounts receivable, net or accrued expenses and other current liabilities. Unbilled revenue is generally billed in the subsequent quarter to their revenue recognition. The Company considers unbilled receivables as short-term in nature as they are normally converted to trade receivables within 90 days, thus future changes in economic conditions will not have a significant effect on the credit loss estimate.
Earnings (loss) per Share	Earnings (loss) per Share Basic earnings (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares outstanding during the period. Diluted earnings per share is computed by dividing net income (loss) by the sum of (1) the weighted-average number of shares of common stock outstanding during the period, and (2) the dilutive effect of assumed conversion of equity awards using the treasury stock method. With respect to the number of weighted-average shares outstanding (denominator), diluted shares reflects: (i) the exercise of options to acquire common stock to the extent that the options’ exercise prices are less than the average market price of common shares during the period and (ii) the pro forma vesting of restricted stock units.
Fair Value Measurements	Fair Value Measurements The Company performs fair value measurements in accordance with the guidance provided by ASC 820, Fair Value Measurements and Disclosures. ASC 820 defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. It also establishes a three level hierarchy that prioritizes the inputs used to measure fair value. Financial instruments measured at fair value on a recurring basis The fair value of contingent consideration liabilities was estimated using a discounted cash flow technique with significant inputs that are not observable in the market and thus represents a Level 3 fair value measurement as defined in ASC 820. The significant inputs in the Level 3 measurement not supported by market activity include the probability assessments of expected future cash flows related to the acquisitions, appropriately discounted considering the uncertainties associated with the obligation, and as calculated in accordance with the terms of the applicable acquisition agreements. Financial instruments not measured at fair value on a recurring basis The Company has evaluated current market conditions and borrower credit quality and has determined that the carrying value of its long-term debt approximates fair value. The fair value of the Company’s notes payable and finance lease obligations approximates their carrying amounts based on anticipated interest rates which management believes would currently be available to the Company for similar issuances of debt.
Segment Disclosure	Segment Disclosure The Company’s three operating segments are: •North America. This segment provides asset protection solutions predominantly in North America, with the largest concentration in the United States, followed by Canada, consisting primarily of NDT, inspection, mechanical and engineering services that are used to evaluate the safety, structural integrity and reliability of critical energy, industrial and public infrastructure and commercial aerospace components. Software, digital and data services are included in this segment. •International. This segment offers services, products and systems similar to those of the other segments to select markets within Europe, the Middle East, Africa, Asia and South America, but not to customers in China and South Korea, which are served by the Products and Systems segment. •Products and Systems. This segment designs, manufactures, sells, installs and services the Company’s asset protection products and systems, including equipment and instrumentation, predominantly in the United States. Costs incurred for general corporate services, including finance, legal, and certain other costs that are provided to the segments are reported within Corporate and eliminations. Sales to the International segment from the Products and Systems segment and subsequent sales by the International segment of the same items are recorded and reflected in the operating performance of both segments. Additionally, engineering charges and royalty fees charged to the North America and International segments by the Products and Systems segment are reflected in the operating performance of each segment. The accounting policies of the reportable segments are the same as those described in Note 1-Description of Business and Basis of Presentation. Segment income from operations is one of the primary performance measures used by the chief operating decision maker, to assess the performance of each segment and make resource allocation decisions. Certain general and administrative costs such as human resources, information technology and training are allocated to the segments. Segment income from operations excludes interest and other financial charges and income taxes. Corporate and other assets are comprised principally of cash, deposits, property, plant and equipment, domestic deferred taxes, deferred charges and other assets. Corporate loss from operations consists of administrative charges related to corporate personnel and other charges that cannot be readily identified for allocation to a particular segment.

Description of Business and Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2023

The Unaudited Condensed Consolidated Financial Statements contained in this report have been prepared in conformity with U.S. generally accepted accounting principles ("GAAP") and Securities and Exchange Commission ("SEC") guidance allowing for reduced disclosure for interim periods. In the opinion of management, the Unaudited Condensed Consolidated Financial Statements include all adjustments, which are of a normal recurring nature, necessary for a fair statement of the results for the interim periods of the years ending December 31, 2023 and December 31, 2022.

Certain items included in these statements are based on management’s estimates. Actual results may differ from those estimates. The results of operations for any interim period are not necessarily indicative of the results expected for the year. The accompanying Unaudited Condensed Consolidated Financial Statements should be read in conjunction with the notes to the Audited Consolidated Financial Statements contained in the Company’s 2022 Annual Report on Form 10-K ("2022 Annual Report").

Principles of Consolidation

The accompanying Unaudited Condensed Consolidated Financial Statements include the accounts of Mistras Group, Inc. as well as its wholly-owned subsidiaries, majority-owned subsidiaries and consolidated variable interest entities (VIE). For subsidiaries in which the Company’s ownership interest is less than 100%, the non-controlling interests are reported in stockholders’ equity in the accompanying Condensed Consolidated Balance Sheets. The non-controlling interests in net results, net of tax, is classified separately in the accompanying Unaudited Condensed Consolidated Statements of Income (Loss). All significant intercompany accounts and transactions have been eliminated in consolidation. The results of operations of companies acquired are included from the date of acquisition.

Reclassification

Certain amounts in prior periods have been reclassified to conform to the current year presentation. Such reclassifications did not have a material effect on the Company’s financial condition or results of operations as previously reported.

Income Taxes

Income taxes are accounted for under the asset and liability method. We recognize deferred tax assets and liabilities at enacted income tax rates for the temporary differences between the financial reporting bases and the tax bases of our assets and liabilities. Any effects of changes in income tax rates or tax laws are included in the provision for income taxes in the period of enactment. Our net deferred tax assets primarily consist of net operating loss carryforwards, or NOLs. A valuation allowance is provided if it is more likely than not that some or all of a deferred income tax asset will not be realized. A current tax liability or asset is recognized for the estimated taxes payable or refundable on tax returns for the current and prior years.

As of September 30, 2023, management concluded that it is more likely than not that a substantial portion of the Company’s deferred tax assets will be realized.

We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate resolution.

The Company’s effective income tax rate was approximately (16.8)% and 31.1% for the three months ended September 30, 2023 and 2022, respectively. The Company’s effective income tax rate was approximately (1.6)% and 48.5% for the nine months ended September 30, 2023 and 2022, respectively.

The effective income tax rate for the three months ended September 30, 2023 was lower than the statutory rate primarily due to the impact of permanent tax adjustments related to executive compensation and goodwill impairments. The effective income tax rate for the three months ended September 30, 2022 was higher than the statutory rate primarily due to various permanent tax adjustments and a $0.1 million valuation allowance recorded on a foreign jurisdiction.

The effective income tax rate for the nine months ended September 30, 2023 was lower than the statutory rate primarily due to the impact of permanent tax adjustments related to executive compensation and goodwill impairments. The effective income tax rate for the nine months ended September 30, 2022 was higher than the statutory rate due primarily to various permanent tax adjustments and a $0.9 million valuation allowance recorded during the period which was related to a foreign jurisdiction.

Recent Accounting Pronouncements

In March 2020 and updated in January 2021, the FASB issued Accounting Standards Update ("ASU") 2020-04 and 2021-01, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The amendments provide optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. The guidance provides optional expedients and exceptions for applying U.S. GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another rate that is expected to be discontinued. The amendments in ASU 2020-04 are effective for all entities as of March 12, 2020 through December 31, 2024. The Company is currently evaluating applicable contracts and the available expedients provided by the new guidance.

Revenue

RevenueThe Company derives the majority of its revenue by providing services on a time and material basis, and are short-term in nature. The Company accounts for revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers.

Performance Obligations

The Company provides highly integrated and bundled inspection services to its customers. The majority of the Company’s contracts have a single performance obligation as the promise to transfer the individual goods or services is not separately identifiable from other promises in the contracts and is, therefore, not distinct. For contracts with multiple performance obligations, the Company allocates the contract’s transaction price to each performance obligation using the Company’s best estimate of the standalone selling price of each distinct good or service in the contract. The primary method used to estimate standalone selling price is a relative selling price based on price lists.

Contract modifications are not routine in the performance of the Company’s contracts. Generally, when contracts are modified, the modification is to account for changes in scope to the goods and services that are provided. In most instances, contract modifications are for goods or services that are distinct, and, therefore, are accounted for as a separate contract.

The Company’s performance obligations are satisfied over time as work progresses or at a point in time. The majority of the Company’s revenue is recognized over time as work progresses for the Company’s service deliverables, which includes providing testing, inspection and mechanical services to our customers. Revenue is recognized over time, based on time and material incurred to date which best portrays the transfer of control to the customer. The Company also utilizes an available practical expedient that provides for revenue to be recognized in an amount that corresponds directly with the value to the customer of the entity’s performance completed to date. Fixed fee arrangements are determined based on expected labor, material, and overhead to be consumed on fulfillment of such services. For these arrangements, revenue is recognized on a cost-to-cost method tracked on an input basis.

The majority of our revenue recognized at a point in time is related to product sales when the customer obtains control of the asset, which is generally upon shipment to the customer. Contract costs include labor, material and overhead.

The Company expects any significant remaining performance obligations to be satisfied within one year.

Contract Estimates

The majority of the Company's revenues are short-term in nature. The Company enters into master service agreements ("MSAs") with customers that specify an overall framework and contract terms. The actual contracting to provide services or furnish products are triggered by a work order, purchase order, or some similar document issued pursuant to a MSA which sets forth the scope of services and/or identifies the products to be provided. From time-to-time, the Company may enter into longer-term contracts, which can range from several months to several years. Revenue on certain contracts is recognized as work is performed based on total costs incurred to date in relation to the total estimated costs for the performance of the contract at completion. This includes contract estimates of costs to be incurred for the performance of the contract. Cost estimation is based upon the professional knowledge and experience of the Company's project managers, engineers and financial professionals. Factors that are considered in estimating the work to be completed include the availability of materials, the effect of any delays in the Company's project performance and the recoverability of any claims. Whenever revisions of estimates, contract costs and/or contract values indicate that the contract costs will exceed estimated revenues, thus creating a loss, a provision for the total estimated loss is recorded in that period.

Contract Balances

The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits (contract liabilities) on the Consolidated Balance Sheets. Amounts are generally billed as work progresses in accordance with agreed-upon contractual terms, generally at periodic intervals (e.g., weekly, bi-weekly or monthly). Generally, billing occurs subsequent to revenue recognition, resulting in contract assets. However, the Company sometimes receives advances or deposits from its customers before revenue is recognized, resulting in contract liabilities. These assets and liabilities are aggregated on an individual contract basis and reported on the Consolidated Balance Sheets at the end of each reporting period within accounts receivable, net or accrued expenses and other current liabilities.

Unbilled revenue is generally billed in the subsequent quarter to their revenue recognition. The Company considers unbilled receivables as short-term in nature as they are normally converted to trade receivables within 90 days, thus future changes in economic conditions will not have a significant effect on the credit loss estimate.

Earnings (loss) per Share

Basic earnings (loss) per share is computed by dividing net income (loss) by the weighted-average number of shares outstanding during the period. Diluted earnings per share is computed by dividing net income (loss) by the sum of (1) the weighted-average number of shares of common stock outstanding during the period, and (2) the dilutive effect of assumed conversion of equity awards using the treasury stock method. With respect to the number of weighted-average shares outstanding (denominator), diluted shares reflects: (i) the exercise of options to acquire common stock to the extent that the options’ exercise prices are less than the average market price of common shares during the period and (ii) the pro forma vesting of restricted stock units.

Fair Value Measurements

The Company performs fair value measurements in accordance with the guidance provided by ASC 820, Fair Value Measurements and Disclosures. ASC 820 defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. It also establishes a three level hierarchy that prioritizes the inputs used to measure fair value.

Financial instruments measured at fair value on a recurring basis

The fair value of contingent consideration liabilities was estimated using a discounted cash flow technique with significant inputs that are not observable in the market and thus represents a Level 3 fair value measurement as defined in ASC 820. The significant inputs in the Level 3 measurement not supported by market activity include the probability assessments of expected future cash flows related to the acquisitions, appropriately discounted considering the uncertainties associated with the obligation, and as calculated in accordance with the terms of the applicable acquisition agreements.

Financial instruments not measured at fair value on a recurring basis

The Company has evaluated current market conditions and borrower credit quality and has determined that the carrying value of its long-term debt approximates fair value. The fair value of the Company’s notes payable and finance lease obligations approximates their carrying amounts based on anticipated interest rates which management believes would currently be available to the Company for similar issuances of debt.

Segment Disclosure

The Company’s three operating segments are:

•North America. This segment provides asset protection solutions predominantly in North America, with the largest concentration in the United States, followed by Canada, consisting primarily of NDT, inspection, mechanical and engineering services that are used to evaluate the safety, structural integrity and reliability of critical energy, industrial and public infrastructure and commercial aerospace components. Software, digital and data services are included in this segment.

•International. This segment offers services, products and systems similar to those of the other segments to select markets within Europe, the Middle East, Africa, Asia and South America, but not to customers in China and South Korea, which are served by the Products and Systems segment.

•Products and Systems. This segment designs, manufactures, sells, installs and services the Company’s asset protection products and systems, including equipment and instrumentation, predominantly in the United States.

Costs incurred for general corporate services, including finance, legal, and certain other costs that are provided to the segments are reported within Corporate and eliminations. Sales to the International segment from the Products and Systems segment and subsequent sales by the International segment of the same items are recorded and reflected in the operating performance of both segments. Additionally, engineering charges and royalty fees charged to the North America and International segments by the Products and Systems segment are reflected in the operating performance of each segment.

The accounting policies of the reportable segments are the same as those described in Note 1-Description of Business and Basis of Presentation. Segment income from operations is one of the primary performance measures used by the chief operating decision maker, to assess the performance of each segment and make resource allocation decisions. Certain general and administrative costs such as human resources, information technology and training are allocated to the segments. Segment income from operations excludes interest and other financial charges and income taxes. Corporate and other assets are

comprised principally of cash, deposits, property, plant and equipment, domestic deferred taxes, deferred charges and other assets. Corporate loss from operations consists of administrative charges related to corporate personnel and other charges that cannot be readily identified for allocation to a particular segment.