Mistras (MG) 10-Q 6 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 02, 2018
Document and Entity Information
Entity Registrant Name	Mistras Group, Inc.
Entity Central Index Key	1,436,126
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		28,543,235
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 17,073	$ 27,541
Accounts receivable, net	155,615	138,080
Inventories	11,133	10,503
Prepaid expenses and other current assets	15,613	18,884
Total current assets	199,434	195,008
Property, plant and equipment, net	86,410	87,143
Intangible assets, net	56,515	63,739
Goodwill	199,625	203,438
Deferred income taxes	1,534	1,606
Other assets	4,630	3,507
Total assets	548,148	554,441
Current Liabilities
Accounts payable	12,937	10,362
Accrued expenses and other current liabilities	73,425	65,561
Current portion of long-term debt	2,225	2,358
Current portion of capital lease obligations	5,085	5,875
Income taxes payable	1,536	6,069
Total current liabilities	95,208	90,225
Long-term debt, net of current portion	147,926	164,520
Obligations under capital leases, net of current portion	8,426	8,738
Deferred income taxes	11,827	8,803
Other long-term liabilities	6,482	11,363
Total liabilities	269,869	283,649
Commitments and contingencies
Equity
Preferred stock, 10,000,000 shares authorized	0	0
Common stock, $0.01 par value, 200,000,000 shares authorized, 28,496,445 and 28,294,968 shares issued	284	282
Additional paid-in capital	226,054	222,425
Retained earnings	72,614	64,717
Accumulated other comprehensive loss	(20,856)	(16,805)
Total Mistras Group, Inc. stockholders’ equity	278,096	270,619
Non-controlling interests	183	173
Total equity	278,279	270,792
Total liabilities and equity	$ 548,148	$ 554,441

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	28,496,445	28,294,968

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Statements of Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 182,169	$ 179,570	$ 561,592	$ 513,326
Cost of revenue	124,260	126,316	389,131	360,144
Depreciation	5,577	5,357	16,902	15,790
Gross profit	52,332	47,897	155,559	137,392
Selling, general and administrative expenses	41,931	38,217	122,232	113,491
Impairment charges	0	15,810	0	15,810
Pension withdrawal expense	5,886	0	5,886	0
Gain on sale of subsidiary	(2,384)	0	(2,384)	0
Research and engineering	745	555	2,414	1,749
Depreciation and amortization	2,920	2,738	8,834	7,854
Litigation expenses	0	1,200	0	1,200
Acquisition-related expense (benefit), net	217	(248)	(1,143)	(589)
Income (loss) from operations	3,017	(10,375)	19,720	(2,123)
Interest expense	1,894	1,081	5,581	3,114
Income (loss) before provision (benefit) for income taxes	1,123	(11,456)	14,139	(5,237)
Provision (benefit) for income taxes	2,133	(4,503)	6,229	(2,199)
Net (loss) income	(1,010)	(6,953)	7,910	(3,038)
Less: net income attributable to non-controlling interests, net of taxes	1	15	13	21
Net (loss) income attributable to Mistras Group, Inc.	$ (1,011)	$ (6,968)	$ 7,897	$ (3,059)
Earnings (loss) per common share:
Basic (in dollars per share)	$ (0.04)	$ (0.25)	$ 0.28	$ (0.11)
Diluted (in dollars per share)	$ (0.04)	$ (0.25)	$ 0.27	$ (0.11)
Weighted average common shares outstanding:
Basic (in shares)	28,429	28,274	28,360	28,465
Diluted (in shares)	28,429	28,274	29,447	28,465

Unaudited Condensed Consolida_2

Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (1,010)	$ (6,953)	$ 7,910	$ (3,038)
Other comprehensive income:
Foreign currency translation adjustments	14	4,443	(4,051)	11,935
Comprehensive (loss) income	(996)	(2,510)	3,859	8,897
Less: comprehensive income attributable to non-controlling interest	0	16	10	25
Comprehensive (loss) income attributable to Mistras Group, Inc.	$ (996)	$ (2,526)	$ 3,849	$ 8,872

Unaudited Condensed Consolida_3

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net (loss) income	$ 7,910	$ (3,038)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization	25,736	23,644
Impairment charges	0	15,810
Deferred income taxes	3,188	(4,755)
Share-based compensation expense	4,760	5,179
Bad debt provision for unexpected customer bankruptcy	0	1,200
Fair value adjustments to contingent consideration	(808)	(880)
Gain on sale of subsidiary	(2,384)	0
Other	825	226
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions
Accounts receivable	(20,258)	(4,017)
Inventories	(1,746)	(838)
Prepaid expenses and other assets	918	995
Accounts payable	3,019	1,466
Accrued expenses and other liabilities	7,456	668
Income taxes payable	(4,432)	(434)
Net cash provided by operating activities	24,184	35,226
Cash flows from investing activities
Purchase of property, plant and equipment	(15,386)	(14,413)
Purchase of intangible assets	(385)	(941)
Acquisition of businesses, net of cash acquired	0	(8,356)
Disposition of businesses, net of cash sold	4,800	0
Proceeds from sale of equipment	1,140	1,194
Net cash used in investing activities	(9,831)	(22,516)
Cash flows from financing activities
Repayment of capital lease obligations	(4,464)	(4,878)
Proceeds from borrowings of long-term debt	1,743	5,599
Repayment of long-term debt	(1,857)	(1,638)
Proceeds from revolver	28,076	38,400
Repayment of revolver	(43,990)	(26,900)
Payment of contingent consideration for business acquisitions	(2,282)	(554)
Purchases of treasury stock	0	(15,923)
Taxes paid related to net share settlement of share-based awards	(1,404)	(1,497)
Proceeds from exercise of stock options	273	277
Net cash used in financing activities	(23,905)	(7,114)
Effect of exchange rate changes on cash and cash equivalents	(916)	2,113
Net change in cash and cash equivalents	(10,468)	7,709
Cash and cash equivalents at beginning of period	27,541	19,154
Cash and cash equivalents at end of period	17,073	26,863
Supplemental disclosure of cash paid
Interest	5,418	3,031
Income taxes	9,658	2,868
Noncash investing and financing
Equipment acquired through capital lease obligations	$ 3,850	$ 2,824

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation Description of Business Mistras Group, Inc. and subsidiaries ("the Company") is a leading “one source” global provider of technology-enabled asset protection solutions used to evaluate the structural integrity and reliability of critical energy, industrial and public infrastructure. The Company combines industry-leading products and technologies, expertise in mechanical integrity (MI), non-destructive testing (NDT) and mechanical services and proprietary data analysis software to deliver a comprehensive portfolio of customized solutions, ranging from routine inspections to complex, plant-wide asset integrity assessments and management. These mission critical solutions enhance customers’ ability to extend the useful life of their assets, increase productivity, minimize repair costs, comply with governmental safety and environmental regulations, manage risk and avoid catastrophic disasters. The Company serves a global customer base of companies with asset-intensive infrastructure, including companies in the oil and gas, commercial aerospace and defense, fossil and nuclear power, alternative and renewable energy, public infrastructure, chemicals, transportation, primary metals and metalworking, pharmaceutical/biotechnology and food processing industries and research and engineering institutions. Basis of Presentation The condensed consolidated financial statements contained in this report are unaudited. In the opinion of management, the condensed consolidated financial statements include all adjustments, which are of a normal recurring nature, necessary for a fair presentation of the results for the interim periods of the fiscal years ending December 31, 2018 and 2017 . 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 Annual Report on Form 10-K (“2017 Annual Report”) for the year ended December 31, 2017 , as filed with the Securities and Exchange Commission on March 14, 2018 . Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of Mistras Group, Inc. and its wholly and majority-owned subsidiaries. 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 income, net of tax, is classified separately in the accompanying condensed consolidated statements of income. All significant intercompany accounts and transactions have been eliminated in consolidation. 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. Customers There were no customers that represented 10% of our revenues for the three and nine months ended September 30, 2018 . One customer accounted for 10% and 11% of our revenues for the three and nine months ended September 30, 2017 , respectively, primarily generated from the Services segment. Significant Accounting Policies The Company’s significant accounting policies are disclosed in Note 2 — Summary of Significant Accounting Policies in the 2017 Annual Report. On an ongoing basis, the Company evaluates its estimates and assumptions, including among other things, those related to revenue recognition, valuations of accounts receivable, long-lived assets, goodwill, deferred tax assets and uncertain tax positions. Since the date of the 2017 Annual Report, there have been no material changes to the Company's significant accounting policies. Income Taxes On December 22, 2017, the United States enacted fundamental changes to federal tax law following the passage of the Tax Cuts and Jobs Act (the “Tax Act”). This was a complex and significant change to the U.S. corporate tax system. The Company was required to account for certain aspects of the Tax Act in its financial statements for the period ended December 31, 2017, including the impact of the Tax Act on existing deferred tax balances and the one-time transition tax on foreign earnings (the “transition tax”). The Company is applying the guidance in Staff Accounting Bulletin (“SAB 118”) in accounting for the enactment date effects of the Tax Act. At December 31, 2017, the Company made a provisional estimate of the transition tax as well as existing deferred balances. As discussed below, we updated certain provisional amounts in consideration of recent guidance and additional information related to the transition tax and the effect of the change in the federal corporate rate on our deferred tax assets. The Company's financial statements for the period ended September 30, 2018 also reflect provisions of the Tax Act effective for periods beginning after December 31, 2017, which includes the reduced federal corporate tax rate from 35% to 21%, adjustments made to executive compensation and meals and entertainment rules, and the inclusion of new categories of income, global intangible low-taxes income (“GILTI”) and foreign derived intangible income (“FDII”). The Company’s effective income tax rate was approximately 190% and 39% for the three months ended September 30, 2018 and 2017 , respectively. The increase in the income tax rate for the three months ended September 30, 2018 is primarily due to the impact of the GILTI and executive compensation provisions resulting from the passage of the Tax Act, and the impact of discrete items described below, which include updating the provisional amounts related to the Tax Act and recording a liability as the result of an ongoing IRS income tax examination. The Company’s effective income tax rate was approximately 44% and 42% for the nine months ended September 30, 2018 and 2017 , respectively. The increase in the income tax rate for the nine months ended September 30, 2018 is due to the impact of the GILTI and executive compensation provisions resulting from the passage of the Tax Act, and the impact of discrete items described below, which include updating the provisional amounts related to the Tax Act and recording a liability as the result of an ongoing IRS income tax examination, offset by lower U.S. tax rates on our domestic income. For the three months ended September 30, 2018, the Company recorded a $1.3 million tax expense, which resulted in a 111% increase in the effective tax rate for this quarter, as an adjustment to certain provisional amounts previously recorded for the Tax Act in consideration of recent guidance and additional information related to the transition tax and the effect of the change in the federal corporate rate on our deferred tax assets. During the first quarter of 2018, the Company has adjusted the Tax Act impact to the deferred tax asset for executive compensation, decreasing the deferred tax asset by approximately $0.4 million due to a change in estimate of 2018 compensation. The Company is continuing to evaluate the state tax impacts of the Tax Act on the period ending December 31, 2017. The amounts recorded in 2018 for the Tax Act related to the calculations of the GILTI, FDII, executive compensation and meals and entertainment are the Company’s best estimates based on the current data and guidance available. The Company is continuing to evaluate the state tax conformity to the Tax Act, including the GILTI provisions. Given the complexity of the new GILTI tax rules, the Company is continuing to evaluate this provision of the Tax Act and the application of ASC 740. Under U.S. Generally Accepted Accounting Principles ("US GAAP" or "GAAP"), the Company is allowed to make an accounting policy choice of either (1) treating taxes due on future U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred (the “period cost method”) or (2) factoring such amounts into a company’s measurement of its deferred taxes (the “deferred method”). Our selection of an accounting policy with respect to the new GILTI tax rules will depend, in part, on analyzing our global income to determine whether the Company expects to have future U.S. inclusions in taxable income related to GILTI and, if so, what the impact is expected to be. The Company is continuing to evaluate the effect of the new GILTI tax rules on future U.S. inclusions in taxable income, including the expected impact on our current structure and business. Therefore, although the Company has considered the current effects of GILTI when estimating our annual effective tax rate, it has not made any adjustments related to potential GILTI tax in our deferred taxes and has not made a policy decision regarding whether to record deferred taxes on GILTI. Mistras and its subsidiaries file tax returns in the U.S., including various state and local returns and in other foreign jurisdictions. The Company believes adequate provision has been made for all income tax uncertainties. The Company is routinely audited by taxing authorities in its filing jurisdictions, and a number of these audits are currently underway. As of September 30, 2018, the Company recorded a liability of $0.4 million as the result of an ongoing IRS income tax examination, which resulted in a 32% increase in the effective tax rate for this quarter. The Company believes that this matter will be resolved within the next twelve months. Recent Accounting Pronouncements In August 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which defers the effective date of ASU 2014-09 for all entities by one year. This update is effective for public business entities for annual reporting periods beginning after December 15, 2017, including interim periods within those reporting periods. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. ASU 2014-09 became effective for the Company on January 1, 2018. The ASU permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the cumulative catch-up transition method). The ASU also requires expanded disclosures relating to the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Additionally, qualitative and quantitative disclosures are required about customer contracts, significant judgments and changes in judgments, and assets recognized from the costs to obtain or fulfill a contract. The Company adopted ASU 2014-09 along with the related additional ASU’s on Topic 606 on January 1, 2018, utilizing the cumulative catch-up method. The result of adoption is immaterial to the Company's consolidated financial statements, largely because most of our projects are short-term in nature and billed on a time and material basis. The Company utilized a 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. See Note 2 for the Company's additional required disclosures under Topic 606. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This amendment supersedes previous accounting guidance ( Topic 840) and requires all leases, with the exception of leases with a term of 12 months or less, to be recorded on the balance sheet as lease assets and lease liabilities. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2018, with early adoption permitted. The standard requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the effect that ASU 2016-02 will have on its condensed consolidated financial statements and related disclosures. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 832), Targeted Improvements. The amendments in this update provide an optional transition method to the modified retrospective method that was part of the initial ASC 842 guidance. The optional transition method allows entities to apply the leasing standard as of January 1, 2019 and recognize a cumulative-effect adjustment to the opening balance of retained earnings for all prior year/comparative period requirements for calendar year 2017 and 2018. The Company plans to adopt this transition method as of January 1, 2019 when ASC 842 becomes effective for the Company. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230). This amendment provides guidance on the presentation and classification of specific cash flow items to improve consistency within the statement of cash flows. ASU 2016-15 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2017, with early adoption permitted. The Company adopted ASU 2016-15 in the first quarter of 2018, which did not have a material impact on the Company's condensed consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350). This amendment eliminates Step Two of the goodwill impairment test. Under the amendments in this update, entities should perform the annual goodwill impairment test by comparing the carrying value of its reporting units to their fair value. An entity should record an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. Tax deductibility of goodwill should be considered in evaluating any reporting unit's impairment loss to be taken. ASU 2017-04 is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company early adopted ASU 2017-04 in the third quarter of 2017 for its condensed consolidated financial statements and related disclosures. In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (Topic 718) Scope of Modification Accounting. This amendment provides guidance concerning which changes to the terms or conditions of a share-based payment require an entity to apply modification accounting. Certain changes to stock awards, notably administrative changes, do not require modification accounting. There are three specific criteria that need to be met in order to prove that modification accounting is not required. ASU 2017-09 is effective for fiscal years, and interim period within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The Company adopted ASU 2017-09 in the first quarter of 2018, which did not have any impact on the Company's condensed consolidated financial statements and related disclosures. In December 2017, the SEC staff issued SAB 118, which provides guidance on accounting for the tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. As of September 30, 2018, the Company made adjustments to certain provisional amounts previously recorded for the Tax Act. Please see Income Taxes above in Note 1 for more details. The Company will complete the accounting for the tax effects of all of the provisions of the Tax Act within the required measurement period not to extend beyond one year from the enactment date.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenue The majority of the Company's revenues are derived from 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, which was adopted on January 1, 2018, using the cumulative catch-up transition method. The adoption of ASC Topic 606 did not impact the Company's condensed consolidated financial statements. Performance Obligations A performance obligation is a promise in a contract to transfer a distinct good or service to the customer, and is the unit of account in ASC Topic 606. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The majority of our 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. The Company provides highly integrated and bundled inspection services to its customers. Some of our contracts have multiple performance obligations, most commonly due to the contract providing both goods and services. For contracts with multiple performance obligations, the Company allocates the contract’s transaction price to each performance obligation using our 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 our 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. Our performance obligations are satisfied over time as work progresses or at a point in time. The majority of our revenue recognized over time as work progresses is related to our 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. 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 our revenues are short-term in nature. The Company has many Master Service Agreements (MSAs) that specify an overall framework and terms of contract when the Company and customers agree upon services or products to be provided. 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 long-term contracts, which can range from several months to several years. Revenue on such long-term 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 our 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 our 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. Revenue by Category The following series of tables present our disaggregated revenues: Revenue by industry was as follows: Three months ended September 30, 2018 Services International Products Corp/Elim Total Oil & Gas $ 90,584 $ 8,843 $ 115 $ — $ 99,542 Aerospace & Defense 12,287 13,117 400 — 25,804 Industrials 17,523 6,080 1,191 — 24,794 Power generation & Transmission 6,341 3,202 1,334 — 10,877 Other Process Industries 6,677 1,650 11 — 8,338 Infrastructure, Research & Engineering 2,629 1,777 1,576 — 5,982 Other 5,299 2,002 1,089 (1,558 ) 6,832 Total $ 141,340 $ 36,671 $ 5,716 $ (1,558 ) $ 182,169 Nine months ended September 30, 2018 Services International Products Corp/Elim Total Oil & Gas $ 287,620 $ 27,512 $ 1,052 $ — $ 316,184 Aerospace & Defense 38,115 42,468 1,836 — 82,419 Industrials 45,847 20,298 2,656 — 68,801 Power generation & Transmission 23,378 6,728 3,444 — 33,550 Other Process Industries 18,222 6,349 49 — 24,620 Infrastructure, Research & Engineering 8,723 6,848 3,337 — 18,908 Other 12,748 6,035 4,912 (6,585 ) 17,110 Total $ 434,653 $ 116,238 $ 17,286 $ (6,585 ) $ 561,592 Revenue per key geographic location was as follows: Three months ended September 30, 2018 Services International Products Corp/Elim Total United States $ 118,415 $ 82 $ 2,806 $ (849 ) $ 120,454 Other Americas 21,712 1,894 192 (141 ) 23,657 Europe 748 33,654 1,184 (557 ) 35,029 Asia-Pacific 465 1,041 1,534 (11 ) 3,029 Total $ 141,340 $ 36,671 $ 5,716 $ (1,558 ) $ 182,169 Nine months ended September 30, 2018 Services International Products Corp/Elim Total United States $ 364,813 $ 506 $ 8,846 $ (2,595 ) $ 371,570 Other Americas 66,170 5,751 552 (1,138 ) 71,335 Europe 3,037 105,499 3,118 (2,752 ) 108,902 Asia-Pacific 633 4,482 4,770 (100 ) 9,785 Total $ 434,653 $ 116,238 $ 17,286 $ (6,585 ) $ 561,592 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 condensed consolidated balance sheet. 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 receive advances or deposits from our customers before revenue is recognized, resulting in contract liabilities. These assets and liabilities are aggregated on an individual contract basis and reported on the condensed consolidated balance sheet at the end of each reporting period. Revenue recognized in 2018, that was included in the contract liability balance at the beginning of the year was $4.5 million . Changes in the contract asset and liability balances during the year ended December 31, 2017, were not materially impacted by any other factors. The Company has elected to utilize a practical expedient to expense incremental costs incurred related to obtaining a contract. The Company’s expenses are expected to be amortized over a period less than one year.

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation The Company has share-based incentive awards outstanding to its eligible employees and non-employee directors under three equity incentive plans: (i) the 2007 Stock Option Plan (the "2007 Plan"), (ii) the 2009 Long-Term Incentive Plan (the "2009 Plan") and (iii) the 2016 Long-Term Incentive Plan (the "2016 Plan"). No further awards may be granted under the 2007 and 2009 Plans, although awards granted under the 2007 and 2009 Plans remain outstanding in accordance with their terms. Awards granted under the 2016 Plan may be in the form of stock options, restricted stock units and other forms of share-based incentives, including performance restricted stock units, stock appreciation rights and deferred stock rights. Stock Options For the three and nine months ended September 30, 2018 and 2017 , the Company did no t recognize any share-based compensation expense related to stock option awards, as all outstanding stock options awards are fully vested. No unrecognized compensation costs remained related to stock option awards as of September 30, 2018 . No stock options were granted during the three and nine months ended September 30, 2018 and September 30, 2017 . The following table sets forth a summary of the stock option activity, weighted average exercise prices and options outstanding as of September 30, 2018 and September 30, 2017 . For the nine months ended September 30, 2018 2017 Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Outstanding at beginning of period: 2,130 $ 13.43 2,167 $ 13.33 Granted — $ — — $ — Exercised (25 ) $ 10.75 (37 ) $ 7.39 Expired or forfeited — $ — — $ — Outstanding at end of period: 2,105 $ 13.47 2,130 $ 13.43 Restricted Stock Unit Awards For the three months ended September 30, 2018 and September 30, 2017 , the Company recognized share-based compensation expense related to restricted stock unit awards of $1.3 million and $1.1 million , respectively. For the nine months ended September 30, 2018 and September 30, 2017 , the Company recognized share-based compensation expense related to restricted stock unit awards of $3.3 million and $3.4 million , respectively. As of September 30, 2018 , there was $7.8 million of unrecognized compensation costs, net of estimated forfeitures, related to restricted stock unit awards, which are expected to be recognized over a remaining weighted average period of 2.5 years . During the first nine months of 2018 and 2017 , the Company granted approximately 19,000 and 21,000 shares, respectively, of fully-vested common stock to its five non-employee directors, as provided for under the Company's non-employee director compensation plan. These shares had grant date fair values of $0.4 million for each respective period, which was recorded as share-based compensation expense during the nine months ended September 30, 2018 and September 30, 2017 , respectively. During the first nine months of 2018 and 2017 , approximately 158,000 and 175,000 restricted stock units vested, respectively. The fair value of these units was $3.4 million and $3.2 million for the nine months ended September 30, 2018 and September 30, 2017 , respectively. Upon vesting, restricted stock units are generally net share-settled to cover the required minimum withholding tax and the remaining amount is converted into an equivalent number of shares of common stock. A summary of the Company's outstanding, non-vested restricted share units is presented below: For the nine months ended September 30, 2018 2017 Units Weighted Units Weighted Outstanding at beginning of period: 532 $ 21.05 569 $ 20.81 Granted 211 $ 19.20 124 $ 21.21 Released (158 ) $ 20.66 (175 ) $ 20.61 Forfeited (34 ) $ 20.36 (30 ) $ 21.21 Outstanding at end of period: 551 $ 20.37 488 $ 20.97 Performance Restricted Stock Units The Company maintains Performance Restricted Stock Units (PRSUs) that have been granted to select executives and senior officers whose ultimate payout is based on the Company’s performance over a one -year period based on three metrics, as defined: (1) Operating Income, (2) Adjusted EBITDAS and (3) Revenue. There also is a discretionary portion of the PRSUs based on individual performance, at the discretion of the Compensation Committee (Discretionary PRSUs). PRSUs and Discretionary PRSUs generally vest ratably on each of the first four anniversary dates upon completion of the performance period, for a total requisite service period of up to five years and have no dividend rights. PRSUs are equity-classified and compensation costs are initially measured using the fair value of the underlying stock at the date of grant, assuming that the target performance conditions will be achieved. Compensation costs related to the PRSUs are subsequently adjusted for changes in the expected outcomes of the performance conditions. Discretionary PRSUs are liability-classified and adjusted to fair value (with a corresponding adjustment to compensation expense) based upon the targeted number of shares to be awarded and the fair value of the underlying stock each reporting period until approved by the Compensation Committee, at which point they are classified as equity. A summary of the Company's PRSU activity is presented below: For the nine months ended September 30, 2018 2017 Units Weighted Units Weighted Outstanding at beginning of period: 278 $ 17.00 290 $ 16.01 Granted 123 $ 19.46 128 $ 20.42 Performance condition adjustments (28 ) $ 19.49 (67 ) $ 20.55 Released (61 ) $ 15.04 (64 ) $ 14.87 Forfeited (12 ) $ 16.16 — $ — Outstanding at end of period: 300 $ 18.05 287 $ 17.07 During the nine months ended September 30, 2018 and September 30, 2017 , the Compensation Committee approved the final calculation of the award metrics for calendar year 2017 and the seven-month transition period ending December 31, 2016, respectively. As a result, the calendar year 2017 PRSUs increased by approximately 4,000 units. There was a decrease of approximately 32,000 units for the nine months ended September 30, 2018 based on forecasted results for calendar 2018. These adjustments comprise the performance condition adjustments for the nine months ended September 30, 2018 noted above. For the seven month transition period PRSUs reduced by approximately 3,000 units after the Compensation Committee approval noted above. There also was a reduction of approximately 64,000 units to the awards granted in calendar 2017 based on forecasted results as of September 30, 2017. These adjustments comprise the performance condition adjustments for the nine months ended September 30, 2017 noted above. As of September 30, 2018, the liability related to Discretionary PRSUs was less than $0.1 million and is classified within accrued expenses and other current liabilities on the condensed consolidated balance sheet. For the three months ended September 30, 2018 and September 30, 2017 , the Company recognized aggregate share-based compensation expense related to the awards described above of approximately $0.4 million for both respective periods. For the nine months ended September 30, 2018 and September 30, 2017 , the Company recognized aggregate share-based compensation expense related to the awards described above of approximately $1.0 million and $1.3 million , respectively. At September 30, 2018 , there was $2.5 million of total unrecognized compensation costs related to approximately 300,000 non-vested PRSUs, which are expected to be recognized over a remaining weighted average period of 2.2 years .

Earnings per Share

Earnings per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Basic earnings per share is computed by dividing net income by the weighted-average number of shares outstanding during the period. Diluted earnings per share is computed by dividing net income 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. The following table sets forth the computations of basic and diluted earnings per share: Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Basic earnings per share: Numerator: Net (loss) income attributable to Mistras Group, Inc. $ (1,011 ) $ (6,968 ) $ 7,897 $ (3,059 ) Denominator: Weighted average common shares outstanding 28,429 28,274 28,360 28,465 Basic earnings per share $ (0.04 ) $ (0.25 ) $ 0.28 $ (0.11 ) Diluted earnings per share: Numerator: Net (loss) income attributable to Mistras Group, Inc. $ (1,011 ) $ (6,968 ) $ 7,897 $ (3,059 ) Denominator: Weighted average common shares outstanding 28,429 28,274 28,360 28,465 Dilutive effect of stock options outstanding n/a (1) n/a (1) 739 n/a (1) Dilutive effect of restricted stock units outstanding n/a (2) n/a (2) 348 n/a (2) 28,429 28,274 29,447 28,465 Diluted earnings per share $ (0.04 ) $ (0.25 ) $ 0.27 $ (0.11 ) (1) - For the three months ended September 30, 2018, 805 shares were excluded from the calculation of diluted EPS due to the net loss for the period. For the three and nine months ended September 30, 2017, 716 and 802 shares, respectively, were excluded from the calculation of diluted EPS due to the net loss for the respective periods. (2) - For the three months ended September 30, 2018, 364 shares were excluded from the calculation of diluted EPS due to the net loss for the period. For the three and nine months ended September 30, 2017, 308 and 337 shares, respectively, were excluded from the calculation of diluted EPS due to the net loss for the respective periods.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Acquisitions	Acquisitions During the nine months ended September 30, 2018 , the Company did no t complete any acquisitions. The assets and liabilities of one of the businesses acquired in 2017 were included in the Company's condensed consolidated balance sheet based upon its estimated fair value on the date of acquisition as determined in a preliminary purchase price allocation, using available information and making assumptions management believed were reasonable. The Company is still in the process of completing its valuation of the assets acquired. The results of operations for this acquisition have been included in the Services segment's results from the date of acquisition. Goodwill of $36.4 million primarily relates to expected synergies and assembled workforce, and is deductible for tax purposes. Other intangible assets, primarily related to customer relationships and covenants not to compete, were $ 23.8 million . During the nine months ended September 30, 2017 , the Company completed two acquisitions, one that performs mechanical services at height, located in Canada, and a company located in the U.S. that primarily performs chemical and specialty process services, primarily in the aerospace industry. In these acquisitions, the Company acquired the assets of one of the acquirees and all of the equity interests of the other acquiree in exchange for aggregate consideration of $8.5 million in cash and contingent consideration up to $5.9 million to be earned based upon the acquired business achieving specific performance metrics over the initial three years of operations from the acquisition date and $1.6 million for working capital adjustments, which were finalized in 2018. The Company accounted for these transactions in accordance with the acquisition method of accounting for business combinations. Dispositions During the fourth quarter of 2017, the Company began the process of marketing one of its subsidiaries in the Products and Systems segment for sale. During the third quarter of 2018, substantially all of the assets and liabilities of the aforementioned subsidiary were sold for approximately $4.3 million , inclusive of a $0.5 million post-closing adjustment. For the nine months ended September 30, 2018, the Company recognized a gain of approximately $2.4 million related to the sale, which is included in its own line on the condensed consolidated income statement. The sale also included a three -year agreement to purchase products from the buyer, with a cumulative commitment of $2.3 million . The agreement is based on third party pricing and the Company's planned purchase requirements over the next three years to meet the minimum purchases, and as a result, the Company concluded that the timing of the gain was appropriate for the three months ended September 30, 2018. The Company determined that the classification of being held for sale had been met as of December 31, 2017. For the three months ended September 30, 2018 , this subsidiary represented 0.1% of the Company's consolidated revenues and loss from operations was $0.2 million . For the nine months ended September 30, 2018 , this subsidiary represented 0.4% of consolidated revenues and loss from operations was $0.4 million . In the aggregate, the assets and liabilities of this subsidiary represents 0.4% and 0.2% of consolidated assets and liabilities, respectively, and are included in their natural classifications on the condensed consolidated balance sheet as of December 31, 2017. Acquisition-Related Expense In the course of its acquisition activities, the Company incurs costs in connection with due diligence, professional fees, and other expenses. Additionally, the Company adjusts the fair value of acquisition-related contingent consideration liabilities on a quarterly basis. These amounts are recorded as acquisition-related expense (benefit), net, on the condensed consolidated statements of income and were as follows for the three and nine months ended September 30, 2018 and 2017 : Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Due diligence, professional fees and other transaction costs $ 35 $ — $ (334 ) $ 291 Adjustments to fair value of contingent consideration liabilities 182 (248 ) (809 ) (880 ) Acquisition-related expense (benefit), net $ 217 $ (248 ) $ (1,143 ) $ (589 )

Accounts Receivable, net

Accounts Receivable, net	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Accounts Receivable, net	Accounts Receivable, net Accounts receivable consisted of the following: September 30, 2018 December 31, 2017 Trade accounts receivable $ 159,206 $ 141,952 Allowance for doubtful accounts (3,591 ) (3,872 ) Accounts receivable, net $ 155,615 $ 138,080 The Company had $28.8 million and $14.4 million of unbilled revenues accrued as of September 30, 2018 and December 31, 2017, respectively. Unbilled revenues are generally billed in the subsequent quarter to their revenue recognition.

Property, Plant and Equipment,

Property, Plant and Equipment, net	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, net	Property, Plant and Equipment, net Property, plant and equipment consisted of the following: Useful Life (Years) September 30, 2018 December 31, 2017 Land $ 2,684 $ 2,414 Buildings and improvements 30-40 24,525 24,003 Office furniture and equipment 5-8 15,208 14,230 Machinery and equipment 5-7 200,875 191,721 243,292 232,368 Accumulated depreciation and amortization (156,882 ) (145,225 ) Property, plant and equipment, net $ 86,410 $ 87,143 Depreciation expense for the three months ended September 30, 2018 and September 30, 2017 was $6.0 million and $5.7 million , respectively. Depreciation expense for the nine months ended September 30, 2018 and September 30, 2017 was $18.2 million and $16.8 million , respectively.

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill Changes in the carrying amount of goodwill by segment is shown below: Services International Products and Systems Total Balance at December 31, 2017 $ 165,801 $ 37,637 $ — $ 203,438 Goodwill acquired during the period — — — — Adjustments to preliminary purchase price allocations (1,977 ) — — (1,977 ) Foreign currency translation (438 ) (1,398 ) — (1,836 ) Balance at September 30, 2018 $ 163,386 $ 36,239 $ — $ 199,625 The Company reviews goodwill for impairment on a reporting unit basis on October 1 of each year and whenever events or changes in circumstances indicate the carrying value of goodwill may not be recoverable. As of September 30, 2018, the Company did not identify any changes in circumstances that would indicate the carrying value of goodwill may not be recoverable. The Company's cumulative goodwill impairment as of September 30, 2018 and December 31, 2017 was $23.1 million , of which $13.2 million related to the Products and Systems segment and $9.9 million related to the International segment.

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2018
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	Intangible Assets The gross amount, accumulated amortization and net carrying amount of intangible assets were as follows: September 30, 2018 December 31, 2017 Useful Life (Years) Gross Amount Accumulated Amortization Net Carrying Amount Gross Amount Accumulated Amortization Impairment Net Carrying Amount Customer relationships 5-14 $ 110,202 $ (59,875 ) $ 50,327 $ 113,299 $ (58,107 ) $ (170 ) $ 55,022 Software/Technology 3-15 14,866 (12,797 ) 2,069 19,523 (14,133 ) (2,411 ) 2,979 Covenants not to compete 2-5 12,080 (10,689 ) 1,391 12,510 (10,438 ) — 2,072 Other 2-12 8,724 (5,996 ) 2,728 10,109 (6,411 ) (32 ) 3,666 Total $ 145,872 $ (89,357 ) $ 56,515 $ 155,441 $ (89,089 ) $ (2,613 ) $ 63,739 Amortization expense for the three months ended September 30, 2018 and September 30, 2017 was $2.5 million and $2.4 million , respectively. Amortization expense for the nine months ended September 30, 2018 and September 30, 2017 was $7.5 million and $6.8 million , respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: September 30, 2018 December 31, 2017 Accrued salaries, wages and related employee benefits $ 31,428 $ 27,185 Contingent consideration, current portion 1,637 3,430 Accrued workers’ compensation and health benefits 4,955 5,181 Deferred revenue 4,783 6,338 Legal settlement accrual — 1,600 Pension accrual 5,886 — Other accrued expenses 24,736 21,827 Total accrued expenses and other current liabilities $ 73,425 $ 65,561

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Long-term debt consisted of the following: September 30, 2018 December 31, 2017 Senior credit facility $ 140,684 $ 156,948 Notes payable 72 228 Other 9,395 9,702 Total debt 150,151 166,878 Less: Current portion (2,225 ) (2,358 ) Long-term debt, net of current portion $ 147,926 $ 164,520 Senior Credit Facility The Company's revolving credit agreement with its banking group ("Credit Agreement") provides the Company with a $250.0 million revolving line of credit, which, under certain circumstances, can be increased to $300.0 million . The Company may borrow up to $30.0 million in non-U.S. Dollar currencies and use up to $10.0 million of the credit limit for the issuance of letters of credit. The Credit Agreement has a maturity date of December 7, 2022. As of September 30, 2018 , the Company had borrowings of $140.7 million and a total of $5.4 million of letters of credit outstanding under the Credit Agreement. Loans under the Credit Agreement bear interest at the London Interbank Offered Rate ( "LIBOR" ) plus an applicable LIBOR margin ranging from 1% to 2% , or a base rate less a margin of 1.25% to 0.375% , at the option of the Company, based upon the Company’s Funded Debt Leverage Ratio. Funded Debt Leverage Ratio is defined as the ratio of (1) all outstanding indebtedness for borrowed money and other interest-bearing indebtedness as of the date of determination to (2) EBITDA (which is (a) net income, less (b) income (or plus loss) from discontinued operations and extraordinary items, plus (c) income tax expenses, plus (d) interest expense, plus (e) depreciation, depletion, and amortization (including non-cash loss on retirement of assets), plus (f) stock compensation expense, less (g) cash expense related to stock compensation, plus (h) certain amounts of EBITDA of acquired business for the prior twelve months, plus (i) certain expenses related to the closing of the Credit Agreement, plus (j) non-cash expenses which do not (in the current or any future period) represent a cash item (excluding non-cash gains which increase net income), plus (k) non-recurring charges (not to exceed $5.0 million in the four consecutive fiscal quarters immediately preceding the date of determination) for items such as severance, lease termination charges, asset write-offs and litigation settlements paid during the period, all determined for the period of four consecutive fiscal quarters immediately preceding the date of determination. The Company has the benefit of the lowest margin if its Funded Debt Leverage Ratio is equal to or less than 0.5 to 1, and the margin increases as the ratio increases, to the maximum margin if the ratio is greater than 2.75 to 1. The Company will also bear additional costs for market disruption, regulatory changes effecting the lenders’ funding costs, and default pricing of an additional 2% interest rate margin on any amounts not paid when due. Amounts borrowed under the Credit Agreement are secured by liens on substantially all of the assets of the Company and is guaranteed by some of our subsidiaries. The Credit Agreement contains financial covenants requiring that the Company maintain a Funded Debt Leverage Ratio of no greater than 3.5 to 1 and an Interest Coverage Ratio of at least 3.0 to 1. Interest Coverage Ratio is defined as the ratio, as of any date of determination, of (a) EBITDA for the 12 month period immediately preceding the date of determination, to (b) all interest, premium payments, debt discount, fees, charges and related expenses of the Company and its subsidiaries in connection with borrowed money (including capitalized interest) or in connection with the deferred purchase price of assets, in each case to the extent treated as interest in accordance with GAAP, paid during the 12 month period immediately preceding the date of determination. The Company can elect to increase the Funded Debt Leverage Ratio to 3.75 to 1 temporarily for four fiscal quarters immediately following the fiscal quarter in which the Company acquires another business. The Company can make this election twice during the term of the Credit Agreement. The Credit Agreement also limits the Company’s ability to, among other things, create liens, make investments, incur more indebtedness, merge or consolidate, make dispositions of property, pay dividends and make distributions to stockholders or repurchase our stock, enter into a new line of business, enter into transactions with affiliates and enter into burdensome agreements. The Credit Agreement does not limit the Company’s ability to acquire other businesses or companies except that the acquired business or company must be in the Company's line of business, the Company must be in compliance with the financial covenants on a pro forma basis after taking into account the acquisition, and, if the acquired business is a separate subsidiary, in certain circumstances the lenders will receive the benefit of a guaranty of the subsidiary and liens on its assets or a pledge of its stock. The Company was in compliance with the terms of the Credit Agreement as of September 30, 2018 , and will continuously monitor its compliance with the covenants contained in its Credit Agreement. Notes Payable and Other In connection with certain of its acquisitions, the Company issued subordinated notes payable to the sellers. The maturity of the notes that remain outstanding are three years from the date of acquisition and bear interest at the prime rate for the Bank of Canada, currently 3.7% as of September 30, 2018. Interest expense is recorded in the condensed consolidated statements of income. The Company's other debt includes local bank financing provided at the local subsidiary levels used to support working capital requirements and fund capital expenditures. At September 30, 2018, there was approximately $9.4 million outstanding, payable at various times from 2018 to 2029. Monthly payments range from $1 thousand to $18 thousand . Interest rates range from 0.5% to 6.2% .

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
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. 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. The following table represents the changes in the fair value of Level 3 contingent consideration: Nine months ended September 30, 2018 2017 Beginning balance $ 5,508 $ 3,094 Acquisitions — 4,126 Payments (2,282 ) (554 ) Accretion of liability 149 198 Revaluation (957 ) (1,078 ) Foreign currency translation (65 ) 28 Ending balance $ 2,353 $ 5,814 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 capital 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.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings and Government Investigations The Company is subject to periodic lawsuits, investigations and claims that arise in the ordinary course of business. The Company cannot predict with certainty the ultimate resolution of lawsuits, investigations and claims asserted against it. Except possibly for certain of the matters described below, the Company does not believe that any currently pending legal proceeding to which the Company is a party will have a material adverse effect on its business, results of operations, cash flows or financial condition. The costs of defense and amounts that may be recovered against the Company may be covered by insurance for certain matters. Litigation and Commercial Claims The Company settled a consolidated purported class and collective action that resulted from the consolidation of two cases originally filed in California state court in April 2015. In connection with the settlement, the Company recorded a pre-tax charge of $6.3 million during the three months ended June 30, 2016 and paid the settlement in February 2017. The Company was a defendant in the lawsuit AGL Services Company v. Mistras Group, Inc., in U.S. District Court for the Northern District of Georgia, filed November 2016. The case involved radiography work performed by the Company in 2012 on the construction of a pipeline project in the U.S. At a trial concluded on October 26, 2017, the jury awarded the plaintiff its damages plus interest, which was fully covered and paid by insurance. The Company’s subsidiary in France has been involved in a dispute with a former owner of a business purchased by the Company’s French subsidiary. The former owner received a judgment in his favor in the amount of $0.4 million for payment of the contingent consideration portion of the purchase price for the business. The Company recorded an accrual for this judgment during 2016. The Company's subsidiary appealed the judgment and the entire judgment was overturned on appeal. The appeal process was completed in July 2018 in the Company's favor, and accordingly, the Company reversed the accrual as of June 30, 2018. The Company was a defendant in a lawsuit, Triumph Aerostructures, LLC d/b/a Triumph Aerostructures-Vought Aircraft Division v. Mistras Group, Inc ., pending in Texas State district court, 193rd Judicial District, Dallas County, Texas, filed September 2016. The plaintiff alleged that in 2014 Mistras delivered a defective Ultrasonic inspection system and alleged damages of approximately $2.3 million , the amount it paid for the system. In January 2018, the Company agreed to settle this matter for a payment of $1.6 million and the return of the underlying ultrasonic inspection components. A charge for $1.6 million was recorded in 2017 and payment was made in February 2018. Government Investigations In May 2015, the Company received a notice from the U.S. Environmental Protection Agency (“EPA”) that it performed a preliminary assessment at a leased facility the Company operates in Cudahy, California. Based upon the preliminary assessment, the EPA is conducting an investigation of the site, which includes taking groundwater and soil samples. The purpose of the investigation is to determine whether any hazardous materials were released from the facility. The Company has been informed that certain hazardous materials and pollutants have been found in the ground water in the general vicinity of the site and the EPA is attempting to ascertain the origination or source of these materials and pollutants. Given the historic industrial use of the site, the EPA determined that the site of the Cudahy facility should be examined, along with numerous other sites in the vicinity. In addition, the California Department of Toxic Substances Control recently notified the owner of the property that it will be performing an additional investigation at the property. At this time, the Company is unable to determine whether it has any liability in connection with this matter and if so, the amount or range of any such liability, and accordingly, has not established any accruals for this matter. Pension Related Contingencies The workforce of certain of the Company’s subsidiaries are unionized and the terms of employment for these workers are governed by collective bargaining agreements, or CBAs. Under these CBAs, the Company’s subsidiaries are required to contribute to the national pension funds for the unions representing these employees, which are multi-employer pension plans. The Company was notified that a significant project was awarded to another contractor in January 2018, and as a result, one of the Company’s subsidiaries experienced a significant reduction in the number of its employees covered by one of the CBAs. Under certain circumstances, such a reduction in the number of employees participating in multi-employer pension plans pursuant to this CBA could result in a complete or partial withdrawal liability to these multi-employer pension plans under the Employee Retirement Income Security Act of 1974 ("ERISA"). Management has been exploring options to retain a level of union work that would avoid withdrawal liability to the pension plans, but concluded during the third quarter that the Company's subsidiaries probably would not obtain sufficient union work to avoid withdrawal liability. As of September 30, 2018, the Company determined that it is probable that its subsidiary will incur a withdrawal liability related to these multi-employer pension plans and estimated that the total amount of this potential liability is approximately $5.9 million . Accordingly, the Company recorded a charge of $5.9 million during the three-month period ended September 30, 2018 for this potential withdrawal liability. Severance and labor disputes During the three and nine months ended September 30, 2018, the Company recorded approximately $1.1 million and $1.2 million , respectively, in charges related to labor claims for its Brazilian subsidiary, which are included within Selling, General and Administrative expenses. These claims related to employees in a company acquired by the Brazilian subsidiary in a prior period. The Company believes it is entitled to indemnification from the sellers of the acquired company for most of these charges, but will not record the expected recovery of indemnification for these labor claims as the amount and timing of collection is uncertain as of September 30, 2018. The Company’s German subsidiary provides employees to customers under temporary staff leasing arrangements. In April 2017, the German Labor Lease Act was passed in Germany limiting the duration of temporary workers to eighteen months, or longer as subsequently agreed with by a customer appropriate authority. Since the passing of the German Labor Lease Act, the Company explored selling its staff leasing services and concluded during the third quarter of 2018 that a sale would not be probable. As of September 30, 2018, the Company had approximately 250 employees under current staff leasing contracts, which expire through 2021. As a result of the above mentioned exploration of selling its staff leasing services, the Company decided that it will not renew several contracts related to these services when they expire beginning in 2019. Accordingly, employees under these contracts will have to be transitioned off the customer contracts because the length of service exceeds the German Labor Lease Act maximum time allowed under the staff leasing arrangements. When these employees are no longer working for a customer under a staff leasing contract, the German subsidiary will terminate these employees and will be required to pay severance to the employees. Employees may also be transitioned to our customers, which would alleviate our severance obligations for those employees. As of September 30, 2018, the Company estimated approximately $1.6 million in severance for these employees, which takes into account our estimate of the employees that would be transitioned to our customers and accordingly recorded an accrual for this amount which is included within Selling, General and Administrative expenses for the three and nine months ended September 30, 2018. Acquisition-related contingencies The Company is liable for contingent consideration in connection with certain of its acquisitions. As of September 30, 2018 , total potential acquisition-related contingent consideration ranged from zero to approximately $5.9 million and would be payable upon the achievement of specific performance metrics by certain of the acquired companies over the next 1.8 years of operations. See Note 5 - Acquisitions to these condensed consolidated financial statements for further discussion of the Company’s acquisitions.

Segment Disclosure

Segment Disclosure	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment Disclosure	Segment Disclosure The Company’s three operating segments are: • Services. 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 and inspection and engineering services that are used to evaluate the structural integrity and reliability of critical energy, commercial aerospace components, industrial and public infrastructure. • 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 Services and International segments by the Products and Systems segment are reflected in the operating performance of each segment. All such intersegment transactions are eliminated in the Company’s consolidated financial reporting. Selected consolidated financial information by segment for the periods shown was as follows (intercompany transactions are eliminated in Corporate and eliminations): Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Revenues Services $ 141,340 $ 137,194 $ 434,653 $ 397,565 International 36,671 38,200 116,238 106,360 Products and Systems 5,716 6,268 17,286 16,925 Corporate and eliminations (1,558 ) (2,092 ) (6,585 ) (7,524 ) $ 182,169 $ 179,570 $ 561,592 $ 513,326 Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Gross profit Services $ 38,838 $ 34,729 $ 113,675 $ 100,432 International 10,877 10,432 34,273 29,720 Products and Systems 2,604 2,753 7,707 7,313 Corporate and eliminations 13 (17 ) (96 ) (73 ) $ 52,332 $ 47,897 $ 155,559 $ 137,392 Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Income (loss) from operations Services $ 8,289 $ 11,699 $ 36,892 $ 31,211 International (662 ) 1,023 2,713 3,866 Products and Systems 2,415 (15,573 ) 2,032 (16,913 ) Corporate and eliminations (7,025 ) (7,524 ) (21,917 ) (20,287 ) $ 3,017 $ (10,375 ) $ 19,720 $ (2,123 ) Income (loss) from operations by operating segment includes intercompany transactions, which are eliminated in Corporate and eliminations. Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Depreciation and amortization Services $ 5,951 $ 5,543 $ 17,892 $ 16,330 International 2,179 2,004 6,720 5,736 Products and Systems 362 594 1,091 1,746 Corporate and eliminations 5 (46 ) 33 (168 ) $ 8,497 $ 8,095 $ 25,736 $ 23,644 September 30, 2018 December 31, 2017 Intangible assets, net Services $ 42,638 $ 46,864 International 11,770 13,899 Products and Systems 1,571 2,261 Corporate and eliminations 536 715 $ 56,515 $ 63,739 September 30, 2018 December 31, 2017 Total assets Services $ 376,694 $ 377,585 International 145,779 150,779 Products and Systems 12,748 12,733 Corporate and eliminations 12,927 13,344 $ 548,148 $ 554,441 Revenues by geographic area for the three and nine months ended September 30, 2018 and 2017 , respectively, were as follows: Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Revenues United States $ 120,454 $ 114,249 $ 371,570 $ 344,808 Other Americas 23,657 26,084 71,335 59,452 Europe 35,029 36,264 108,902 97,630 Asia-Pacific 3,029 2,973 9,785 11,436 $ 182,169 $ 179,570 $ 561,592 $ 513,326

Repurchase of Common Stock

Repurchase of Common Stock	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Repurchase of Common Stock	Repurchase of Common Stock The Company's Board of Directors approved a $50 million stock repurchase plan in 2015. As part of this plan, on August 17, 2016, the Company entered into an agreement with its then CEO, Dr. Sotirios Vahaviolos, to purchase up to 1 million of his shares, commencing in October 2016. Pursuant to the agreement, in general, the Company purchased from Dr. Vahaviolos up to $2 million of shares each month, at a 2% discount to the average daily closing price of the Company's common stock for the preceding month. From the inception of the plan through December 31, 2017, the Company purchased 1,000,000 shares from Dr. Vahaviolos at an average price of $21.92 per share for an aggregate cost of approximately $21.9 million and approximately 146,000 shares in the open market at an average price of $20.48 per share, for an aggregate cost of approximately $3.0 million . The Company retired all its repurchased shares during the fourth quarter of 2017 and they are not included in common stock issued and outstanding as of September 30, 2018 and December 31, 2017. There were no repurchases of common stock during the nine months ended September 30, 2018 . As of September 30, 2018, approximately $25.1 million remained available to repurchase shares under the stock repurchase plan.

Description of Business and B_2

Description of Business and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements contained in this report are unaudited. In the opinion of management, the condensed consolidated financial statements include all adjustments, which are of a normal recurring nature, necessary for a fair presentation of the results for the interim periods of the fiscal years ending December 31, 2018 and 2017 . 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 Annual Report on Form 10-K (“2017 Annual Report”) for the year ended December 31, 2017 , as filed with the Securities and Exchange Commission on March 14, 2018 .
Principles of Consolidation	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of Mistras Group, Inc. and its wholly and majority-owned subsidiaries. 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 income, net of tax, is classified separately in the accompanying condensed consolidated statements of income. All significant intercompany accounts and transactions have been eliminated in consolidation.
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 On December 22, 2017, the United States enacted fundamental changes to federal tax law following the passage of the Tax Cuts and Jobs Act (the “Tax Act”). This was a complex and significant change to the U.S. corporate tax system. The Company was required to account for certain aspects of the Tax Act in its financial statements for the period ended December 31, 2017, including the impact of the Tax Act on existing deferred tax balances and the one-time transition tax on foreign earnings (the “transition tax”). The Company is applying the guidance in Staff Accounting Bulletin (“SAB 118”) in accounting for the enactment date effects of the Tax Act. At December 31, 2017, the Company made a provisional estimate of the transition tax as well as existing deferred balances. As discussed below, we updated certain provisional amounts in consideration of recent guidance and additional information related to the transition tax and the effect of the change in the federal corporate rate on our deferred tax assets. The Company's financial statements for the period ended September 30, 2018 also reflect provisions of the Tax Act effective for periods beginning after December 31, 2017, which includes the reduced federal corporate tax rate from 35% to 21%, adjustments made to executive compensation and meals and entertainment rules, and the inclusion of new categories of income, global intangible low-taxes income (“GILTI”) and foreign derived intangible income (“FDII”). Mistras and its subsidiaries file tax returns in the U.S., including various state and local returns and in other foreign jurisdictions. The Company believes adequate provision has been made for all income tax uncertainties.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which defers the effective date of ASU 2014-09 for all entities by one year. This update is effective for public business entities for annual reporting periods beginning after December 15, 2017, including interim periods within those reporting periods. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. ASU 2014-09 became effective for the Company on January 1, 2018. The ASU permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the cumulative catch-up transition method). The ASU also requires expanded disclosures relating to the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Additionally, qualitative and quantitative disclosures are required about customer contracts, significant judgments and changes in judgments, and assets recognized from the costs to obtain or fulfill a contract. The Company adopted ASU 2014-09 along with the related additional ASU’s on Topic 606 on January 1, 2018, utilizing the cumulative catch-up method. The result of adoption is immaterial to the Company's consolidated financial statements, largely because most of our projects are short-term in nature and billed on a time and material basis. The Company utilized a 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. See Note 2 for the Company's additional required disclosures under Topic 606. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This amendment supersedes previous accounting guidance ( Topic 840) and requires all leases, with the exception of leases with a term of 12 months or less, to be recorded on the balance sheet as lease assets and lease liabilities. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2018, with early adoption permitted. The standard requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the effect that ASU 2016-02 will have on its condensed consolidated financial statements and related disclosures. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 832), Targeted Improvements. The amendments in this update provide an optional transition method to the modified retrospective method that was part of the initial ASC 842 guidance. The optional transition method allows entities to apply the leasing standard as of January 1, 2019 and recognize a cumulative-effect adjustment to the opening balance of retained earnings for all prior year/comparative period requirements for calendar year 2017 and 2018. The Company plans to adopt this transition method as of January 1, 2019 when ASC 842 becomes effective for the Company. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230). This amendment provides guidance on the presentation and classification of specific cash flow items to improve consistency within the statement of cash flows. ASU 2016-15 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2017, with early adoption permitted. The Company adopted ASU 2016-15 in the first quarter of 2018, which did not have a material impact on the Company's condensed consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350). This amendment eliminates Step Two of the goodwill impairment test. Under the amendments in this update, entities should perform the annual goodwill impairment test by comparing the carrying value of its reporting units to their fair value. An entity should record an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. Tax deductibility of goodwill should be considered in evaluating any reporting unit's impairment loss to be taken. ASU 2017-04 is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company early adopted ASU 2017-04 in the third quarter of 2017 for its condensed consolidated financial statements and related disclosures. In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (Topic 718) Scope of Modification Accounting. This amendment provides guidance concerning which changes to the terms or conditions of a share-based payment require an entity to apply modification accounting. Certain changes to stock awards, notably administrative changes, do not require modification accounting. There are three specific criteria that need to be met in order to prove that modification accounting is not required. ASU 2017-09 is effective for fiscal years, and interim period within those fiscal years, beginning after December 15, 2017, with early adoption permitted. The Company adopted ASU 2017-09 in the first quarter of 2018, which did not have any impact on the Company's condensed consolidated financial statements and related disclosures. In December 2017, the SEC staff issued SAB 118, which provides guidance on accounting for the tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. As of September 30, 2018, the Company made adjustments to certain provisional amounts previously recorded for the Tax Act. Please see Income Taxes above in Note 1 for more details. The Company will complete the accounting for the tax effects of all of the provisions of the Tax Act within the required measurement period not to extend beyond one year from the enactment date.
Revenue	Revenue The majority of the Company's revenues are derived from 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, which was adopted on January 1, 2018, using the cumulative catch-up transition method. The adoption of ASC Topic 606 did not impact the Company's condensed consolidated financial statements. Performance Obligations A performance obligation is a promise in a contract to transfer a distinct good or service to the customer, and is the unit of account in ASC Topic 606. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The majority of our 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. The Company provides highly integrated and bundled inspection services to its customers. Some of our contracts have multiple performance obligations, most commonly due to the contract providing both goods and services. For contracts with multiple performance obligations, the Company allocates the contract’s transaction price to each performance obligation using our 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 our 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. Our performance obligations are satisfied over time as work progresses or at a point in time. The majority of our revenue recognized over time as work progresses is related to our 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. 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 our revenues are short-term in nature. The Company has many Master Service Agreements (MSAs) that specify an overall framework and terms of contract when the Company and customers agree upon services or products to be provided. 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 long-term contracts, which can range from several months to several years. Revenue on such long-term 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 our 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 our 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 condensed consolidated balance sheet. 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 receive advances or deposits from our customers before revenue is recognized, resulting in contract liabilities. These assets and liabilities are aggregated on an individual contract basis and reported on the condensed consolidated balance sheet at the end of each reporting period.
Fair Value Measurements	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 capital 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. 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. 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.

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregated Revenues by Industry and Key Geographic Location	The following series of tables present our disaggregated revenues: Revenue by industry was as follows: Three months ended September 30, 2018 Services International Products Corp/Elim Total Oil & Gas $ 90,584 $ 8,843 $ 115 $ — $ 99,542 Aerospace & Defense 12,287 13,117 400 — 25,804 Industrials 17,523 6,080 1,191 — 24,794 Power generation & Transmission 6,341 3,202 1,334 — 10,877 Other Process Industries 6,677 1,650 11 — 8,338 Infrastructure, Research & Engineering 2,629 1,777 1,576 — 5,982 Other 5,299 2,002 1,089 (1,558 ) 6,832 Total $ 141,340 $ 36,671 $ 5,716 $ (1,558 ) $ 182,169 Nine months ended September 30, 2018 Services International Products Corp/Elim Total Oil & Gas $ 287,620 $ 27,512 $ 1,052 $ — $ 316,184 Aerospace & Defense 38,115 42,468 1,836 — 82,419 Industrials 45,847 20,298 2,656 — 68,801 Power generation & Transmission 23,378 6,728 3,444 — 33,550 Other Process Industries 18,222 6,349 49 — 24,620 Infrastructure, Research & Engineering 8,723 6,848 3,337 — 18,908 Other 12,748 6,035 4,912 (6,585 ) 17,110 Total $ 434,653 $ 116,238 $ 17,286 $ (6,585 ) $ 561,592 Revenue per key geographic location was as follows: Three months ended September 30, 2018 Services International Products Corp/Elim Total United States $ 118,415 $ 82 $ 2,806 $ (849 ) $ 120,454 Other Americas 21,712 1,894 192 (141 ) 23,657 Europe 748 33,654 1,184 (557 ) 35,029 Asia-Pacific 465 1,041 1,534 (11 ) 3,029 Total $ 141,340 $ 36,671 $ 5,716 $ (1,558 ) $ 182,169 Nine months ended September 30, 2018 Services International Products Corp/Elim Total United States $ 364,813 $ 506 $ 8,846 $ (2,595 ) $ 371,570 Other Americas 66,170 5,751 552 (1,138 ) 71,335 Europe 3,037 105,499 3,118 (2,752 ) 108,902 Asia-Pacific 633 4,482 4,770 (100 ) 9,785 Total $ 434,653 $ 116,238 $ 17,286 $ (6,585 ) $ 561,592

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Stock Option Activity, Weighted Average Exercise Prices and Options Outstanding	The following table sets forth a summary of the stock option activity, weighted average exercise prices and options outstanding as of September 30, 2018 and September 30, 2017 . For the nine months ended September 30, 2018 2017 Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Outstanding at beginning of period: 2,130 $ 13.43 2,167 $ 13.33 Granted — $ — — $ — Exercised (25 ) $ 10.75 (37 ) $ 7.39 Expired or forfeited — $ — — $ — Outstanding at end of period: 2,105 $ 13.47 2,130 $ 13.43
Schedule of Company's Outstanding, Nonvested Restricted Share Units and Performance Restricted Stock Units	A summary of the Company's PRSU activity is presented below: For the nine months ended September 30, 2018 2017 Units Weighted Units Weighted Outstanding at beginning of period: 278 $ 17.00 290 $ 16.01 Granted 123 $ 19.46 128 $ 20.42 Performance condition adjustments (28 ) $ 19.49 (67 ) $ 20.55 Released (61 ) $ 15.04 (64 ) $ 14.87 Forfeited (12 ) $ 16.16 — $ — Outstanding at end of period: 300 $ 18.05 287 $ 17.07 A summary of the Company's outstanding, non-vested restricted share units is presented below: For the nine months ended September 30, 2018 2017 Units Weighted Units Weighted Outstanding at beginning of period: 532 $ 21.05 569 $ 20.81 Granted 211 $ 19.20 124 $ 21.21 Released (158 ) $ 20.66 (175 ) $ 20.61 Forfeited (34 ) $ 20.36 (30 ) $ 21.21 Outstanding at end of period: 551 $ 20.37 488 $ 20.97

Earnings per Share (Tables)

Earnings per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of Computations of Basic and Diluted Earnings per Share	The following table sets forth the computations of basic and diluted earnings per share: Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Basic earnings per share: Numerator: Net (loss) income attributable to Mistras Group, Inc. $ (1,011 ) $ (6,968 ) $ 7,897 $ (3,059 ) Denominator: Weighted average common shares outstanding 28,429 28,274 28,360 28,465 Basic earnings per share $ (0.04 ) $ (0.25 ) $ 0.28 $ (0.11 ) Diluted earnings per share: Numerator: Net (loss) income attributable to Mistras Group, Inc. $ (1,011 ) $ (6,968 ) $ 7,897 $ (3,059 ) Denominator: Weighted average common shares outstanding 28,429 28,274 28,360 28,465 Dilutive effect of stock options outstanding n/a (1) n/a (1) 739 n/a (1) Dilutive effect of restricted stock units outstanding n/a (2) n/a (2) 348 n/a (2) 28,429 28,274 29,447 28,465 Diluted earnings per share $ (0.04 ) $ (0.25 ) $ 0.27 $ (0.11 ) (1) - For the three months ended September 30, 2018, 805 shares were excluded from the calculation of diluted EPS due to the net loss for the period. For the three and nine months ended September 30, 2017, 716 and 802 shares, respectively, were excluded from the calculation of diluted EPS due to the net loss for the respective periods. (2) - For the three months ended September 30, 2018, 364 shares were excluded from the calculation of diluted EPS due to the net loss for the period. For the three and nine months ended September 30, 2017, 308 and 337 shares, respectively, were excluded from the calculation of diluted EPS due to the net loss for the respective periods.

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Schedule of Acquisition-Related Expenses	In the course of its acquisition activities, the Company incurs costs in connection with due diligence, professional fees, and other expenses. Additionally, the Company adjusts the fair value of acquisition-related contingent consideration liabilities on a quarterly basis. These amounts are recorded as acquisition-related expense (benefit), net, on the condensed consolidated statements of income and were as follows for the three and nine months ended September 30, 2018 and 2017 : Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Due diligence, professional fees and other transaction costs $ 35 $ — $ (334 ) $ 291 Adjustments to fair value of contingent consideration liabilities 182 (248 ) (809 ) (880 ) Acquisition-related expense (benefit), net $ 217 $ (248 ) $ (1,143 ) $ (589 )

Accounts Receivable, net (Table

Accounts Receivable, net (Tables)	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Schedule of Accounts Receivable, Net	Accounts receivable consisted of the following: September 30, 2018 December 31, 2017 Trade accounts receivable $ 159,206 $ 141,952 Allowance for doubtful accounts (3,591 ) (3,872 ) Accounts receivable, net $ 155,615 $ 138,080

Property, Plant and Equipment_2

Property, Plant and Equipment, net (Tables)	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment, Net	Property, plant and equipment consisted of the following: Useful Life (Years) September 30, 2018 December 31, 2017 Land $ 2,684 $ 2,414 Buildings and improvements 30-40 24,525 24,003 Office furniture and equipment 5-8 15,208 14,230 Machinery and equipment 5-7 200,875 191,721 243,292 232,368 Accumulated depreciation and amortization (156,882 ) (145,225 ) Property, plant and equipment, net $ 86,410 $ 87,143

Goodwill (Tables)

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Changes in the carrying amount of goodwill by segment is shown below: Services International Products and Systems Total Balance at December 31, 2017 $ 165,801 $ 37,637 $ — $ 203,438 Goodwill acquired during the period — — — — Adjustments to preliminary purchase price allocations (1,977 ) — — (1,977 ) Foreign currency translation (438 ) (1,398 ) — (1,836 ) Balance at September 30, 2018 $ 163,386 $ 36,239 $ — $ 199,625

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Schedule of Gross Amount, Accumulated Amortization and Net Carrying Amount of Intangibles	The gross amount, accumulated amortization and net carrying amount of intangible assets were as follows: September 30, 2018 December 31, 2017 Useful Life (Years) Gross Amount Accumulated Amortization Net Carrying Amount Gross Amount Accumulated Amortization Impairment Net Carrying Amount Customer relationships 5-14 $ 110,202 $ (59,875 ) $ 50,327 $ 113,299 $ (58,107 ) $ (170 ) $ 55,022 Software/Technology 3-15 14,866 (12,797 ) 2,069 19,523 (14,133 ) (2,411 ) 2,979 Covenants not to compete 2-5 12,080 (10,689 ) 1,391 12,510 (10,438 ) — 2,072 Other 2-12 8,724 (5,996 ) 2,728 10,109 (6,411 ) (32 ) 3,666 Total $ 145,872 $ (89,357 ) $ 56,515 $ 155,441 $ (89,089 ) $ (2,613 ) $ 63,739

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following: September 30, 2018 December 31, 2017 Accrued salaries, wages and related employee benefits $ 31,428 $ 27,185 Contingent consideration, current portion 1,637 3,430 Accrued workers’ compensation and health benefits 4,955 5,181 Deferred revenue 4,783 6,338 Legal settlement accrual — 1,600 Pension accrual 5,886 — Other accrued expenses 24,736 21,827 Total accrued expenses and other current liabilities $ 73,425 $ 65,561

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Long-Term Debt	Long-term debt consisted of the following: September 30, 2018 December 31, 2017 Senior credit facility $ 140,684 $ 156,948 Notes payable 72 228 Other 9,395 9,702 Total debt 150,151 166,878 Less: Current portion (2,225 ) (2,358 ) Long-term debt, net of current portion $ 147,926 $ 164,520

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Changes in Fair Value of Level 3 Contingent Consideration	The following table represents the changes in the fair value of Level 3 contingent consideration: Nine months ended September 30, 2018 2017 Beginning balance $ 5,508 $ 3,094 Acquisitions — 4,126 Payments (2,282 ) (554 ) Accretion of liability 149 198 Revaluation (957 ) (1,078 ) Foreign currency translation (65 ) 28 Ending balance $ 2,353 $ 5,814

Segment Disclosure (Tables)

Segment Disclosure (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of Consolidated Financial Information by Segment	Selected consolidated financial information by segment for the periods shown was as follows (intercompany transactions are eliminated in Corporate and eliminations): Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Revenues Services $ 141,340 $ 137,194 $ 434,653 $ 397,565 International 36,671 38,200 116,238 106,360 Products and Systems 5,716 6,268 17,286 16,925 Corporate and eliminations (1,558 ) (2,092 ) (6,585 ) (7,524 ) $ 182,169 $ 179,570 $ 561,592 $ 513,326 Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Gross profit Services $ 38,838 $ 34,729 $ 113,675 $ 100,432 International 10,877 10,432 34,273 29,720 Products and Systems 2,604 2,753 7,707 7,313 Corporate and eliminations 13 (17 ) (96 ) (73 ) $ 52,332 $ 47,897 $ 155,559 $ 137,392 Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Income (loss) from operations Services $ 8,289 $ 11,699 $ 36,892 $ 31,211 International (662 ) 1,023 2,713 3,866 Products and Systems 2,415 (15,573 ) 2,032 (16,913 ) Corporate and eliminations (7,025 ) (7,524 ) (21,917 ) (20,287 ) $ 3,017 $ (10,375 ) $ 19,720 $ (2,123 ) Income (loss) from operations by operating segment includes intercompany transactions, which are eliminated in Corporate and eliminations. Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Depreciation and amortization Services $ 5,951 $ 5,543 $ 17,892 $ 16,330 International 2,179 2,004 6,720 5,736 Products and Systems 362 594 1,091 1,746 Corporate and eliminations 5 (46 ) 33 (168 ) $ 8,497 $ 8,095 $ 25,736 $ 23,644 September 30, 2018 December 31, 2017 Intangible assets, net Services $ 42,638 $ 46,864 International 11,770 13,899 Products and Systems 1,571 2,261 Corporate and eliminations 536 715 $ 56,515 $ 63,739 September 30, 2018 December 31, 2017 Total assets Services $ 376,694 $ 377,585 International 145,779 150,779 Products and Systems 12,748 12,733 Corporate and eliminations 12,927 13,344 $ 548,148 $ 554,441
Schedule of Revenues by Geographic Areas	Revenues by geographic area for the three and nine months ended September 30, 2018 and 2017 , respectively, were as follows: Three months ended Nine months ended September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Revenues United States $ 120,454 $ 114,249 $ 371,570 $ 344,808 Other Americas 23,657 26,084 71,335 59,452 Europe 35,029 36,264 108,902 97,630 Asia-Pacific 3,029 2,973 9,785 11,436 $ 182,169 $ 179,570 $ 561,592 $ 513,326

Description of Business and B_3

Description of Business and Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Concentration Risk [Line Items]
Effective income tax rate	190.00%		39.00%	44.00%	42.00%
Adjustment to deferred tax assets due to change in estimate for executive compensation as result of Tax Act	$ 1.3	$ 0.4
Increase in effective tax rate related to transition tax and change in federal corporate rate	111.00%
Domestic Tax Authority | IRS
Concentration Risk [Line Items]
Liability recorded as result of income tax examination	$ 0.4			$ 0.4
Increase in effective tax rate as result of income tax examination	32.00%
Customer Concentration Risk | Revenues | Customer A
Concentration Risk [Line Items]
Concentration risk, percentage			10.00%		11.00%

Revenue - Additional Informatio

Revenue - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Revenue, remaining performance obligation, expected timing of satisfaction period	1 year
Revenue recognized that was included in contract liability balance at the beginning of the year	$ 4.5
Revenue, practical expedient, incremental cost of obtaining a contract, maximum period	1 year

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 182,169	$ 179,570	$ 561,592	$ 513,326
United States
Disaggregation of Revenue [Line Items]
Revenues	120,454	114,249	371,570	344,808
Other Americas
Disaggregation of Revenue [Line Items]
Revenues	23,657	26,084	71,335	59,452
Europe
Disaggregation of Revenue [Line Items]
Revenues	35,029	36,264	108,902	97,630
Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenues	3,029	2,973	9,785	11,436
Oil & Gas
Disaggregation of Revenue [Line Items]
Revenues	99,542		316,184
Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenues	25,804		82,419
Industrials
Disaggregation of Revenue [Line Items]
Revenues	24,794		68,801
Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenues	10,877		33,550
Other Process Industries
Disaggregation of Revenue [Line Items]
Revenues	8,338		24,620
Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenues	5,982		18,908
Other
Disaggregation of Revenue [Line Items]
Revenues	6,832		17,110
Operating segments | Services
Disaggregation of Revenue [Line Items]
Revenues	141,340	137,194	434,653	397,565
Operating segments | Services | United States
Disaggregation of Revenue [Line Items]
Revenues	118,415		364,813
Operating segments | Services | Other Americas
Disaggregation of Revenue [Line Items]
Revenues	21,712		66,170
Operating segments | Services | Europe
Disaggregation of Revenue [Line Items]
Revenues	748		3,037
Operating segments | Services | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenues	465		633
Operating segments | Services | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenues	90,584		287,620
Operating segments | Services | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenues	12,287		38,115
Operating segments | Services | Industrials
Disaggregation of Revenue [Line Items]
Revenues	17,523		45,847
Operating segments | Services | Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenues	6,341		23,378
Operating segments | Services | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenues	6,677		18,222
Operating segments | Services | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenues	2,629		8,723
Operating segments | Services | Other
Disaggregation of Revenue [Line Items]
Revenues	5,299		12,748
Operating segments | International
Disaggregation of Revenue [Line Items]
Revenues	36,671	38,200	116,238	106,360
Operating segments | International | United States
Disaggregation of Revenue [Line Items]
Revenues	82		506
Operating segments | International | Other Americas
Disaggregation of Revenue [Line Items]
Revenues	1,894		5,751
Operating segments | International | Europe
Disaggregation of Revenue [Line Items]
Revenues	33,654		105,499
Operating segments | International | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenues	1,041		4,482
Operating segments | International | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenues	8,843		27,512
Operating segments | International | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenues	13,117		42,468
Operating segments | International | Industrials
Disaggregation of Revenue [Line Items]
Revenues	6,080		20,298
Operating segments | International | Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenues	3,202		6,728
Operating segments | International | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenues	1,650		6,349
Operating segments | International | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenues	1,777		6,848
Operating segments | International | Other
Disaggregation of Revenue [Line Items]
Revenues	2,002		6,035
Operating segments | Products
Disaggregation of Revenue [Line Items]
Revenues	5,716	6,268	17,286	16,925
Operating segments | Products | United States
Disaggregation of Revenue [Line Items]
Revenues	2,806		8,846
Operating segments | Products | Other Americas
Disaggregation of Revenue [Line Items]
Revenues	192		552
Operating segments | Products | Europe
Disaggregation of Revenue [Line Items]
Revenues	1,184		3,118
Operating segments | Products | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenues	1,534		4,770
Operating segments | Products | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenues	115		1,052
Operating segments | Products | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenues	400		1,836
Operating segments | Products | Industrials
Disaggregation of Revenue [Line Items]
Revenues	1,191		2,656
Operating segments | Products | Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenues	1,334		3,444
Operating segments | Products | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenues	11		49
Operating segments | Products | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenues	1,576		3,337
Operating segments | Products | Other
Disaggregation of Revenue [Line Items]
Revenues	1,089		4,912
Corp/Elim
Disaggregation of Revenue [Line Items]
Revenues	(1,558)	$ (2,092)	(6,585)	$ (7,524)
Corp/Elim | United States
Disaggregation of Revenue [Line Items]
Revenues	(849)		(2,595)
Corp/Elim | Other Americas
Disaggregation of Revenue [Line Items]
Revenues	(141)		(1,138)
Corp/Elim | Europe
Disaggregation of Revenue [Line Items]
Revenues	(557)		(2,752)
Corp/Elim | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenues	(11)		(100)
Corp/Elim | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenues	0		0
Corp/Elim | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenues	0		0
Corp/Elim | Industrials
Disaggregation of Revenue [Line Items]
Revenues	0		0
Corp/Elim | Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenues	0		0
Corp/Elim | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenues	0		0
Corp/Elim | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenues	0		0
Corp/Elim | Other
Disaggregation of Revenue [Line Items]
Revenues	$ (1,558)		$ (6,585)

Share-Based Compensation - Equi

Share-Based Compensation - Equity Incentive Plans (Details)	9 Months Ended
	Sep. 30, 2018planshares
Share-based compensation
Number of employee stock ownership plans (plan) | plan	3
2007 Plan
Share-based compensation
Number of awards that may be granted (in shares)	0
2009 Plan
Share-based compensation
Number of awards that may be granted (in shares)	0

Share-Based Compensation - Stoc

Share-Based Compensation - Stock Options (Details) - Stock Options - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Common Stock Options (in shares)
Outstanding at the beginning of the period: (in shares)			2,130,000	2,167,000
Granted (in shares)	0	0	0	0
Exercised (in shares)			(25,000)	(37,000)
Expired or forfeited (in shares)			0	0
Outstanding at the end of the period: (in shares)	2,105,000	2,130,000	2,105,000	2,130,000
Weighted Average Exercise Price (in dollar per share)
Outstanding at the beginning of period: (in dollars per share)			$ 13.43	$ 13.33
Granted (in dollars per share)			0	0
Exercised (in dollars per share)			10.75	7.39
Expired or forfeited (in dollars per share)			0	0
Outstanding at the end of period: (in dollars per share)	$ 13.47	$ 13.43	$ 13.47	$ 13.43
Recognized share-based compensation expense (less than)	$ 0	$ 0	$ 0	$ 0
Unrecognized compensation costs	$ 0		$ 0

Share-Based Compensation - Rest

Share-Based Compensation - Restricted Stock Unit Awards - Narrative (Details) - Restricted Stock Units shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)directorshares	Sep. 30, 2017USD ($)directorshares
Share-based compensation
Recognized share-based compensation expense (benefit)	$ 1.3	$ 1.1	$ 3.3	$ 3.4
Unrecognized compensation cost, net of estimated forfeitures	$ 7.8		$ 7.8
Weighted-average period over which unrecognized compensation cost is expected to be recognized (years)			2 years 6 months
Fair value of shares vested			$ 3.4	$ 3.2
Shares vested (in shares) | shares			158	175
Non-employee directors
Share-based compensation
Number of fully vested common stock granted (in shares) | shares			19	21
Number of non-employee directors to whom fully vested common stock is granted (director) | director			5	5
Fair value of shares vested			$ 0.4	$ 0.4

Share-Based Compensation - Re_2

Share-Based Compensation - Restricted Stock Units Awards - Activity (Details) - Restricted Stock Units - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Restricted Stock Units Awards (Units)
Outstanding at beginning of period: (in shares)	532	569
Granted (in shares)	211	124
Released (in shares)	(158)	(175)
Forfeited (in shares)	(34)	(30)
Outstanding at end of period: (in shares)	551	488
Weighted Average Grant-Date Fair Value (in dollars per share)
Outstanding at the beginning of period: (in dollars per share)	$ 21.05	$ 20.81
Granted (in dollars per share)	19.20	21.21
Released (in dollars per share)	20.66	20.61
Forfeited (in dollars per share)	20.36	21.21
Outstanding at end of period: (in dollars per share)	$ 20.37	$ 20.97

Share-Based Compensation - Perf

Share-Based Compensation - Performance Restricted Stock Units - Narrative (Details) - PRSUs shares in Thousands, $ in Millions	3 Months Ended		7 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2018USD ($)shares	Sep. 30, 2017USD ($)shares	Dec. 31, 2016shares	Sep. 30, 2018USD ($)performance_metricshares	Sep. 30, 2017USD ($)shares	Dec. 31, 2017shares
Share-based compensation
Number of units increased during the period (in shares) | shares						4
Number of units decreased during the period (in shares) | shares			3	32	64
Recognized share-based compensation expense (benefit) | $	$ 0.4	$ 0.4		$ 1	$ 1.3
Unrecognized compensation cost | $	$ 2.5			$ 2.5
Nonvested shares outstanding (in shares) | shares	300	287	290	300	287	278
Weighted-average period over which unrecognized compensation cost is expected to be recognized (years)				2 years 2 months 12 days
Accrued expenses and other liabilities
Share-based compensation
Accrued liability related to discretionary PRSUs | $	$ 0.1			$ 0.1
Executive and Senior Officers
Share-based compensation
Performance period (years)				1 year
Number of performance award metrics | performance_metric				3
Requisite service period (years)				5 years
Executive and Senior Officers | Anniversary 1
Share-based compensation
Award vesting rights, percentage				25.00%
Executive and Senior Officers | Anniversary 2
Share-based compensation
Award vesting rights, percentage				25.00%
Executive and Senior Officers | Anniversary 3
Share-based compensation
Award vesting rights, percentage				25.00%
Executive and Senior Officers | Anniversary 4
Share-based compensation
Award vesting rights, percentage				25.00%

Share-Based Compensation - Pe_2

Share-Based Compensation - Performance Restricted Stock Units - Activity (Details) - PRSUs - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Performance Restricted Stock (Units)
Outstanding at beginning of period: (in shares)	278	290
Granted (in shares)	123	128
Performance condition adjustments (in shares)	(28)	(67)
Released (in shares)	(61)	(64)
Forfeited (in shares)	(12)	0
Outstanding at end of period: (in shares)	300	287
Weighted Average Grant-Date Fair Value (in dollars per share)
Outstanding at the beginning of period: (in dollars per share)	$ 17	$ 16.01
Granted (in dollars per share)	19.46	20.42
Performance condition adjustments (in dollars per share)	19.49	20.55
Released (in dollars per share)	15.04	14.87
Forfeited (in dollars per share)	16.16	0
Outstanding at end of period: (in dollars per share)	$ 18.05	$ 17.07

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic earnings per share:
Net (loss) income attributable to Mistras Group, Inc.	$ (1,011)	$ (6,968)	$ 7,897	$ (3,059)
Denominator:
Weighted average common shares outstanding (in shares)	28,429	28,274	28,360	28,465
Basic earnings (loss) per share (in dollars per share)	$ (0.04)	$ (0.25)	$ 0.28	$ (0.11)
Denominator:
Weighted average common shares outstanding (in shares)	28,429	28,274	28,360	28,465
Dilutive effect of stock options outstanding (in shares)			739
Dilutive effect of restricted stock units outstanding (in shares)			348
Weighted average common shares outstanding, diluted (in shares)	28,429	28,274	29,447	28,465
Diluted earnings (loss) per share (in dollars per share)	$ (0.04)	$ (0.25)	$ 0.27	$ (0.11)
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares excluded from calculation of diluted EPS due to net loss position (in shares)	805	716		802
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares excluded from calculation of diluted EPS due to net loss position (in shares)	364	308		337

Acquisitions (Details)

Acquisitions (Details) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2018entity	Sep. 30, 2017USD ($)entity	Dec. 31, 2017USD ($)entity
Acquisitions
Number of acquisitions | entity	0	2	1
Business deductible for tax purposes			$ 36.4
Cash paid for acquisitions		$ 8.5
Contingent consideration from acquisitions		$ 5.9
Initial period over which potential acquisition-related contingent consideration would be payable		3 years
Acquisition working capital adjustments		$ 1.6
Canada
Acquisitions
Number of acquisitions | entity		1
United States
Acquisitions
Number of acquisitions | entity		1
Customer Relationships and Covenants Not To Compete
Acquisitions
Intangible assets acquired			$ 23.8

Acquisitions - Dispositions (De

Acquisitions - Dispositions (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018USD ($)	Dec. 31, 2017subsidiary	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of subsidiary	$ 2,384		$ 0	$ 2,384	$ 0
Foreign Subsidiaries | Products and Systems | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of subsidiaries classified as held for sale | subsidiary		1
Percentage of consolidated revenues of subsidiary held for sale	0.10%			0.40%
Loss from operations of subsidiary held for sale	$ 200			$ 400
Percentage of consolidated assets of subsidiary held for sale		0.40%
Percentage of liabilities of subsidiary held for sale		0.20%
Foreign Subsidiaries | Products and Systems | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received on sale of subsidiary	4,300			4,300
Post-closing adjustment included in consideration received from sale of subsidiary	$ 500			$ 500
Term of agreement to purchase products from the buyer on sale of subsidiary	3 years
Amount of purchased commitment to buy products from the buyer on sale of subsidiary	$ 2,300
Foreign Subsidiaries | Products and Systems | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Selling, General and Administrative Expenses
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of subsidiary	$ 2,400

Acquisitions - Acquisition-Rela

Acquisitions - Acquisition-Related Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Combinations [Abstract]
Due diligence, professional fees and other transaction costs	$ 35	$ 0	$ (334)	$ 291
Adjustments to fair value of contingent consideration liabilities	182	(248)	(809)	(880)
Acquisition-related expense (benefit), net	$ 217	$ (248)	$ (1,143)	$ (589)

Accounts Receivable, net (Detai

Accounts Receivable, net (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade accounts receivable	$ 159,206	$ 141,952
Allowance for doubtful accounts	(3,591)	(3,872)
Accounts receivable, net	155,615	138,080
Unbilled revenues accrued	$ 28,800	$ 14,400

Property, Plant and Equipment_3

Property, Plant and Equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 243,292		$ 243,292		$ 232,368
Accumulated depreciation and amortization	(156,882)		(156,882)		(145,225)
Property, plant and equipment, net	86,410		86,410		87,143
Depreciation expense	6,000	$ 5,700	18,200	$ 16,800
Land
Property, Plant and Equipment, net
Property, plant and equipment, gross	2,684		2,684		2,414
Buildings and improvements
Property, Plant and Equipment, net
Property, plant and equipment, gross	24,525		$ 24,525		24,003
Buildings and improvements | Minimum
Property, Plant and Equipment, net
Useful Life (Years)			30 years
Buildings and improvements | Maximum
Property, Plant and Equipment, net
Useful Life (Years)			40 years
Office furniture and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross	15,208		$ 15,208		14,230
Office furniture and equipment | Minimum
Property, Plant and Equipment, net
Useful Life (Years)			5 years
Office furniture and equipment | Maximum
Property, Plant and Equipment, net
Useful Life (Years)			8 years
Machinery and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 200,875		$ 200,875		$ 191,721
Machinery and equipment | Minimum
Property, Plant and Equipment, net
Useful Life (Years)			5 years
Machinery and equipment | Maximum
Property, Plant and Equipment, net
Useful Life (Years)			7 years

Goodwill (Details)

Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)
Goodwill [Roll Forward]
Balance at December 31, 2017	$ 203,438
Goodwill acquired during the period	0
Adjustments to preliminary purchase price allocations	(1,977)
Foreign currency translation	(1,836)
Balance at September 30, 2018	199,625
Services
Goodwill [Roll Forward]
Balance at December 31, 2017	165,801
Goodwill acquired during the period	0
Adjustments to preliminary purchase price allocations	(1,977)
Foreign currency translation	(438)
Balance at September 30, 2018	163,386
International
Goodwill [Roll Forward]
Balance at December 31, 2017	37,637
Goodwill acquired during the period	0
Adjustments to preliminary purchase price allocations	0
Foreign currency translation	(1,398)
Balance at September 30, 2018	36,239
Products and Systems
Goodwill [Roll Forward]
Balance at December 31, 2017	0
Goodwill acquired during the period	0
Adjustments to preliminary purchase price allocations	0
Foreign currency translation	0
Balance at September 30, 2018	$ 0

Goodwill - Additional Informati

Goodwill - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill cumulative impairment loss	$ 23.1	$ 23.1
Products and Systems
Goodwill [Line Items]
Goodwill cumulative impairment loss	13.2	13.2
International
Goodwill [Line Items]
Goodwill cumulative impairment loss	$ 9.9	$ 9.9

Intangible Assets (Details)

Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 145,872		$ 145,872		$ 155,441
Accumulated Amortization	(89,357)		(89,357)		(89,089)
Impairment					(2,613)
Net Carrying Amount	56,515		56,515		63,739
Amortization expense	2,500	$ 2,400	7,500	$ 6,800
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Amount	110,202		110,202		113,299
Accumulated Amortization	(59,875)		(59,875)		(58,107)
Impairment					(170)
Net Carrying Amount	50,327		$ 50,327		55,022
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			5 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			14 years
Software/Technology
Finite-Lived Intangible Assets [Line Items]
Gross Amount	14,866		$ 14,866		19,523
Accumulated Amortization	(12,797)		(12,797)		(14,133)
Impairment					(2,411)
Net Carrying Amount	2,069		$ 2,069		2,979
Software/Technology | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			3 years
Software/Technology | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			15 years
Covenants not to compete
Finite-Lived Intangible Assets [Line Items]
Gross Amount	12,080		$ 12,080		12,510
Accumulated Amortization	(10,689)		(10,689)		(10,438)
Impairment					0
Net Carrying Amount	1,391		$ 1,391		2,072
Covenants not to compete | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			2 years
Covenants not to compete | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			5 years
Other
Finite-Lived Intangible Assets [Line Items]
Gross Amount	8,724		$ 8,724		10,109
Accumulated Amortization	(5,996)		(5,996)		(6,411)
Impairment					(32)
Net Carrying Amount	$ 2,728		$ 2,728		$ 3,666
Other | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			2 years
Other | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)			12 years

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued salaries, wages and related employee benefits	$ 31,428	$ 27,185
Contingent consideration, current portion	1,637	3,430
Accrued workers’ compensation and health benefits	4,955	5,181
Deferred revenue	4,783	6,338
Legal settlement accrual	0	1,600
Pension accrual	5,886	0
Other accrued expenses	24,736	21,827
Total accrued expenses and other current liabilities	$ 73,425	$ 65,561

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt	$ 150,151	$ 166,878
Less: Current portion	(2,225)	(2,358)
Long-term debt, net of current portion	147,926	164,520
Senior credit facility
Debt Instrument [Line Items]
Total debt	140,684	156,948
Notes payable
Debt Instrument [Line Items]
Total debt	72	228
Other
Debt Instrument [Line Items]
Total debt	$ 9,395	$ 9,702

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details)	Dec. 08, 2017USD ($)quarter	Oct. 31, 2014quarter	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Notes Payable and Other
Debt outstanding			$ 150,151,000	$ 166,878,000
Senior credit facility
Senior Credit Facility
Maximum borrowing capacity			250,000,000
Line of credit facility, higher borrowing capacity option			300,000,000
Maximum borrowing capacity in non-U.S. Dollar currencies			30,000,000
Maximum amount available for the issuance of letters of credit			10,000,000
Outstanding borrowings			140,700,000
Outstanding letters of credit			5,400,000
Amount of non-recurring charges used as threshold used for calculation of funded debt leverage ratio	$ 5,000,000
Number of consecutive fiscal quarters used for calculating funded debt leverage ratio | quarter	4	4
Funded debt leverage ratio at which the entity will have the benefit of lowest interest margin (less than or equal to)		0.5
Funded debt leverage ratio at which the entity will bear the maximum interest rate margin (greater than)		2.75
Additional interest rate margin if funded debt leverage ratio exceeds threshold (as a percent)		2.00%
Funded debt leverage ratio for additional interest payment (less than)		3.5
Interest coverage ratio (greater than)		3
Preceding period used for calculating Interest Coverage Ratio	12 months	12 months
Number of fiscal quarters to temporary increase funded debt leverage ratio | quarter	4
Notes Payable and Other
Debt outstanding			$ 140,684,000	156,948,000
Senior credit facility | Maximum
Senior Credit Facility
Temporary increase in funded debt leverage ratio	3.75
Senior credit facility | LIBOR
Senior Credit Facility
Reference rate, description		"LIBOR"
Senior credit facility | LIBOR | Minimum
Senior Credit Facility
Margin (as a percent)		1.00%
Senior credit facility | LIBOR | Maximum
Senior Credit Facility
Margin (as a percent)		2.00%
Senior credit facility | Base rate
Senior Credit Facility
Reference rate, description		base rate
Senior credit facility | Base rate | Minimum
Senior Credit Facility
Margin (as a percent)		(0.375%)
Senior credit facility | Base rate | Maximum
Senior Credit Facility
Margin (as a percent)		(1.25%)
Notes payable
Notes Payable and Other
Interest rate (as a percent)			3.70%
Debt outstanding			$ 72,000	228,000
Notes payable | Minimum
Notes Payable and Other
Maturity term from the date of acquisition			3 years
Other
Notes Payable and Other
Debt outstanding			$ 9,395,000	$ 9,702,000
Other | Minimum
Notes Payable and Other
Interest rate (as a percent)			0.50%
Debt monthly periodic payments			$ 1,000
Other | Maximum
Notes Payable and Other
Interest rate (as a percent)			6.20%
Debt monthly periodic payments			$ 18,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Contingent Consideration Liability [Roll Forward]
Revaluation	$ 182	$ (248)	$ (809)	$ (880)
Ending balance		5,900		5,900
Level 3
Contingent Consideration Liability [Roll Forward]
Beginning balance			5,508	3,094
Acquisitions			0	4,126
Payments			(2,282)	(554)
Accretion of liability			149	198
Revaluation			(957)	(1,078)
Foreign currency translation			(65)	28
Ending balance	$ 2,353	$ 5,814	$ 2,353	$ 5,814

Commitments and Contingencies (

Commitments and Contingencies (Details)	1 Months Ended				3 Months Ended			9 Months Ended		10 Months Ended	12 Months Ended
	Jan. 31, 2018USD ($)	Apr. 30, 2017	Sep. 30, 2016USD ($)	Apr. 30, 2015claim	Sep. 30, 2018USD ($)subsidiaryemployeearrangement	Sep. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Sep. 30, 2018USD ($)subsidiaryemployeearrangement	Sep. 30, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2017USD ($)
Litigation
Litigation expenses					$ 0	$ 1,200,000		$ 0	$ 1,200,000
Charge recorded related to liability for potential withdrawal from multi-employer pension plan					$ 5,886,000	$ 0		$ 5,886,000	$ 0
Consolidated class and collective action lawsuit | Settled Litigation
Litigation
Number of consolidated claims settled | claim				2
Litigation expenses							$ 6,300,000
Dispute with former owner of company's French subsidiary | Settled Litigation | AGL Services Company v. Mistras Group | Affiliated Entity
Litigation
Litigation settlement, amount awarded to other party										$ 400,000
Defective ultrasound inspection system | Settled Litigation
Litigation
Amount of damages claimed			$ 2,300,000
Defective ultrasound inspection system | Settled Litigation | Triumph Aerostructures-Vought Aircraft Division v. Mistras Group
Litigation
Litigation expenses											$ 1,600,000
Litigation settlement, amount awarded to other party	$ 1,600,000
Pension related contingencies | Pending Litigation
Litigation
Number of Company's subsidiaries that could experience significant decline in employees covered by collective-bargaining arrangement | subsidiary					1			1
Number of collective-bargaining agreements with significant decline in employees covered | arrangement					1			1
Estimated potential liability for withdrawal from multi-employer pension plan					$ 5,900,000			$ 5,900,000
Charge recorded related to liability for potential withdrawal from multi-employer pension plan					5,900,000
Severance and labor disputes | Pending Litigation | NDT Do Brazil, LTDA | Selling, General and Administrative Expenses
Litigation
Contingency charges					$ 1,100,000			$ 1,200,000
Severance and labor disputes | Pending Litigation | Affiliated Entity | GERMANY
Litigation
Temporary employment contract period		18 months
Number of employees under current staff leasing contracts | employee					250			250
Severance and labor disputes | Pending Litigation | Affiliated Entity | GERMANY | Selling, General and Administrative Expenses
Litigation
Contingency charges					$ 1,600,000			$ 1,600,000
Acquisition-related contingencies
Litigation
Potential acquisition-related contingent consideration, low end of range					0			0
Potential acquisition-related contingent consideration, high end of range					$ 5,900,000			$ 5,900,000
Remaining period over which potential acquisition-related contingent consideration would be payable								1 year 9 months 18 days

Segment Disclosure - Financial

Segment Disclosure - Financial Information by Segment (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)segment	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			3
Financial information by segment
Revenues	$ 182,169	$ 179,570	$ 561,592	$ 513,326
Gross profit	52,332	47,897	155,559	137,392
Income (loss) from operations	3,017	(10,375)	19,720	(2,123)
Depreciation and amortization	8,497	8,095	25,736	23,644
Intangible assets, net	56,515		56,515		$ 63,739
Total assets	548,148		548,148		554,441
Operating segments | Services
Financial information by segment
Revenues	141,340	137,194	434,653	397,565
Gross profit	38,838	34,729	113,675	100,432
Income (loss) from operations	8,289	11,699	36,892	31,211
Depreciation and amortization	5,951	5,543	17,892	16,330
Intangible assets, net	42,638		42,638		46,864
Total assets	376,694		376,694		377,585
Operating segments | International
Financial information by segment
Revenues	36,671	38,200	116,238	106,360
Gross profit	10,877	10,432	34,273	29,720
Income (loss) from operations	(662)	1,023	2,713	3,866
Depreciation and amortization	2,179	2,004	6,720	5,736
Intangible assets, net	11,770		11,770		13,899
Total assets	145,779		145,779		150,779
Operating segments | Products and Systems
Financial information by segment
Revenues	5,716	6,268	17,286	16,925
Gross profit	2,604	2,753	7,707	7,313
Income (loss) from operations	2,415	(15,573)	2,032	(16,913)
Depreciation and amortization	362	594	1,091	1,746
Intangible assets, net	1,571		1,571		2,261
Total assets	12,748		12,748		12,733
Corporate and eliminations
Financial information by segment
Revenues	(1,558)	(2,092)	(6,585)	(7,524)
Gross profit	13	(17)	(96)	(73)
Income (loss) from operations	(7,025)	(7,524)	(21,917)	(20,287)
Depreciation and amortization	5	$ (46)	33	$ (168)
Intangible assets, net	536		536		715
Total assets	$ 12,927		$ 12,927		$ 13,344

Segment Disclosure - Revenues b

Segment Disclosure - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue and long-lived assets by geographic area
Revenues	$ 182,169	$ 179,570	$ 561,592	$ 513,326
United States
Revenue and long-lived assets by geographic area
Revenues	120,454	114,249	371,570	344,808
Other Americas
Revenue and long-lived assets by geographic area
Revenues	23,657	26,084	71,335	59,452
Europe
Revenue and long-lived assets by geographic area
Revenues	35,029	36,264	108,902	97,630
Asia-Pacific
Revenue and long-lived assets by geographic area
Revenues	$ 3,029	$ 2,973	$ 9,785	$ 11,436

Repurchase of Common Stock (Det

Repurchase of Common Stock (Details) - Stock Repurchase Plan - USD ($)	Aug. 17, 2016	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2015
Class of Stock [Line Items]
Stock repurchase plan, amount approved				$ 50,000,000
Treasury stock repurchased (in shares)		0	146,000
Treasury stock acquired, average price (in dollars per share)			$ 20.48
Treasury stock acquired, aggregate cost			$ 3,000,000
Stock repurchase plan, remaining amount approved		$ 25,100,000
Chairman and CEO
Class of Stock [Line Items]
Stock repurchase plan, amount approved (in shares)	1,000,000
Stock repurchase plan, amount approved each month from CEO	$ 2,000,000
Average daily price of common stock for the preceding month discount, percent	2.00%
Treasury stock repurchased (in shares)			1,000,000
Treasury stock acquired, average price (in dollars per share)			$ 21.92
Treasury stock acquired, aggregate cost			$ 21,900,000