Mistras (MG) 10-K 15 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Mar. 12, 2019	Jun. 30, 2018
Document and Entity Information
Entity Registrant Name	Mistras Group, Inc.
Entity Central Index Key	0001436126
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Public Float			$ 327.2
Entity Common Stock, Shares Outstanding		28,562,708
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 25,544	$ 27,541
Accounts receivable, net	148,324	138,080
Inventories	13,053	10,503
Prepaid expenses and other current assets	15,870	18,884
Total current assets	202,791	195,008
Property, plant and equipment, net	93,895	87,143
Intangible assets, net	111,395	63,739
Goodwill	279,259	203,438
Deferred income taxes	1,930	1,606
Other assets	4,767	3,507
Total Assets	694,037	554,441
Current Liabilities
Accounts payable	13,863	10,362
Accrued expenses and other current liabilities	73,895	65,561
Current portion of long-term debt	6,833	2,358
Current portion of capital lease obligations	3,922	5,875
Income taxes payable	1,958	6,069
Total current liabilities	100,471	90,225
Long-term debt, net of current portion	283,787	164,520
Obligations under capital leases, net of current portion	9,075	8,738
Deferred income taxes	23,148	8,803
Other long-term liabilities	6,482	11,363
Total Liabilities	422,963	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, 28,562,608 and 28,294,968 shares issued	285	282
Additional paid-in capital	226,616	222,425
Retained earnings	71,553	64,717
Accumulated other comprehensive loss	(27,557)	(16,805)
Total Mistras Group, Inc. stockholders’ equity	270,897	270,619
Non-controlling interests	177	173
Total Equity	271,074	270,792
Total Liabilities and Equity	$ 694,037	$ 554,441

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 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)	28,562,608	28,294,968

Consolidated Statements of Inco

Consolidated Statements of Income (Loss) - USD ($) shares in Thousands, $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Income Statement [Abstract]
Revenue	$ 404,161	$ 742,354	$ 700,970	$ 719,181
Cost of revenue	274,298	512,024	492,238	494,911
Depreciation	12,859	22,456	21,020	21,262
Gross profit	117,004	207,874	187,712	203,008
Selling, general and administrative expenses	91,058	166,352	153,025	141,229
Impairment charges	0	0	15,810	0
Pension withdrawal expense	0	5,886	0	0
Gain on sale of subsidiary	0	(2,384)	0	0
Research and engineering	1,577	3,310	2,272	2,523
Depreciation and amortization	6,340	11,957	10,363	11,212
Acquisition-related expense (benefit), net	496	532	482	(1,453)
Litigation charges	0	0	1,600	6,320
Income from operations	17,533	22,221	4,160	43,177
Interest expense	2,052	7,950	4,386	4,762
Income (loss) before provision for income taxes	15,481	14,271	(226)	38,415
Provision for income taxes	5,870	7,426	1,942	13,765
Net income (loss)	9,611	6,845	(2,168)	24,650
Less: net income (loss) attributable to noncontrolling interests, net of taxes	43	9	7	(4)
Net income (loss) attributable to Mistras Group, Inc.	$ 9,568	$ 6,836	$ (2,175)	$ 24,654
Earnings (loss) per common share
Basic (in dollars per share)	$ 0.33	$ 0.24	$ (0.08)	$ 0.85
Diluted (in dollars per share)	$ 0.32	$ 0.23	$ (0.08)	$ 0.82
Weighted average common shares outstanding:
Basic (in shares)	28,989	28,406	28,422	28,856
Diluted (in shares)	30,125	29,427	28,422	29,891

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 9,611	$ 6,845	$ (2,168)	$ 24,650
Other comprehensive (loss) income:
Foreign currency translation adjustments	(9,625)	(10,752)	12,919	1,014
Comprehensive (loss) income	(14)	(3,907)	10,751	25,664
Less: net income (loss) attributable to noncontrolling interests	43	9	7	(4)
Foreign currency translation adjustments attributable to noncontrolling interests	6	(5)	4	1
Comprehensive (loss) income attributable to Mistras Group, Inc.	$ (51)	$ (3,921)	$ 10,748	$ 25,669

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Total Mistras Group, Inc. Stockholders’ Equity	Common Stock	Treasury Stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Noncontrolling Interest
Balance (in shares) at May. 31, 2015			28,703	0
Balance at May. 31, 2015	$ 245,012	$ 244,819	$ 287	$ 0	$ 208,064	$ 57,581	$ (21,113)	$ 193
Increase (Decrease) in Stockholders' Equity
Net income (loss)	24,650	24,654				24,654		(4)
Other comprehensive income (loss), net of tax	950	1,014					1,014	(64)
Share-based payments	6,394	6,394			6,394
Net settlement on vesting of restricted stock units (in shares)			182
Net settlement on vesting of restricted stock units	(1,091)	(1,091)	$ 2		(1,093)
Excess tax benefit from share-based payment compensation	$ (170)	(170)			(170)
Exercise of stock options (in shares)	55		55
Exercise of stock options	$ 543	543	$ 1		542
Balance (in shares) at May. 31, 2016			28,940	0
Balance at May. 31, 2016	276,288	276,163	$ 290	$ 0	213,737	82,235	(20,099)	125
Increase (Decrease) in Stockholders' Equity
Net income (loss)	9,611	9,568				9,568		43
Other comprehensive income (loss), net of tax	(9,631)	(9,625)					(9,625)	(6)
Share-based payments	4,627	4,627			4,627
Net settlement on vesting of restricted stock units (in shares)			212
Net settlement on vesting of restricted stock units	(2,323)	(2,323)	$ 2		(2,325)
Excess tax benefit from share-based payment compensation	568	568			568
Purchase of treasury stock (in shares)				(420)
Purchase of treasury stock	$ (9,000)	(9,000)		$ (9,000)
Exercise of stock options (in shares)	65		65
Exercise of stock options	$ 604	604			604
Balance (in shares) at Dec. 31, 2016			29,217	420
Balance at Dec. 31, 2016	270,744	270,582	$ 292	$ 9,000	217,211	91,803	(29,724)	162
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(2,168)	(2,175)				(2,175)		7
Other comprehensive income (loss), net of tax	12,923	12,919					12,919	4
Share-based payments	6,588	6,588			6,588
Net settlement on vesting of restricted stock units (in shares)			187
Net settlement on vesting of restricted stock units	(1,647)	(1,647)	$ 2		(1,649)
Retirement of treasury stock (in shares)			(1,146)	1,146
Retirement of treasury stock	0		$ (12)	$ 24,923		(24,911)
Purchase of treasury stock (in shares)				(726)
Purchase of treasury stock	$ (15,923)	(15,923)		$ (15,923)
Exercise of stock options (in shares)	37		37
Exercise of stock options	$ 275	275			275
Balance (in shares) at Dec. 31, 2017			28,295	0
Balance at Dec. 31, 2017	270,792	270,619	$ 282	$ 0	222,425	64,717	(16,805)	173
Increase (Decrease) in Stockholders' Equity
Net income (loss)	6,845	6,836				6,836		9
Other comprehensive income (loss), net of tax	(10,757)	(10,752)					(10,752)	(5)
Share-based payments (in shares)			243
Share-based payments	6,109	6,109	$ 3		6,106
Net settlement on vesting of restricted stock units	$ (2,188)	(2,188)			(2,188)
Exercise of stock options (in shares)	25		25
Exercise of stock options	$ 273	273			273
Balance (in shares) at Dec. 31, 2018			28,563	0
Balance at Dec. 31, 2018	$ 271,074	$ 270,897	$ 285	$ 0	$ 226,616	$ 71,553	$ (27,557)	$ 177

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Cash flows from operating activities
Net income (loss)	$ 9,611	$ 6,845	$ (2,168)	$ 24,650
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation and amortization	19,199	34,413	31,383	32,474
Deferred income taxes	(174)	1,859	(4,854)	240
Share-based compensation expense	4,559	6,107	6,574	6,514
Impairment charges	0	0	15,810	0
Bad debt provision for troubled customers	0	650	1,200	0
Gain on sale of subsidiary	0	(2,384)	0	0
Fair value adjustments to contingent consideration	262	(716)	(463)	(2,066)
Other	559	1,773	79	(1,052)
Changes in operating assets and liabilities, net of effect of acquisitions
Accounts receivable	4,123	(10,349)	2,490	(4,999)
Inventories	628	(2,764)	(117)	1,595
Prepaid expenses and other assets	(4,453)	1,400	(1,904)	(1,812)
Accounts payable	(3,667)	2,948	2,574	254
Accrued expenses and other liabilities	(2,301)	5,663	4,188	10,187
Income taxes payable	1,913	(3,781)	1,007	2,139
Net cash provided by operating activities	30,259	41,664	55,799	68,124
Cash flows from investing activities
Purchase of property, plant and equipment	(9,093)	(20,584)	(19,314)	(14,864)
Purchase of intangible assets	(697)	(541)	(1,255)	(1,315)
Disposition of business	0	4,239	0	0
Acquisition of businesses, net of cash acquired	(8,262)	(139,980)	(83,424)	(1,743)
Proceeds from sale of equipment	678	1,416	1,196	1,170
Net cash used in investing activities	(17,374)	(155,450)	(102,797)	(16,752)
Cash flows from financing activities
Repayment of capital lease obligations	(4,490)	(5,813)	(6,492)	(7,870)
Proceeds from borrowings of long-term debt	386	2,358	6,653	2,737
Repayment of long-term debt	(11,919)	(2,746)	(2,101)	(17,580)
Proceeds from revolver	48,400	175,176	124,000	55,800
Repayments of revolver	(34,300)	(49,991)	(50,600)	(69,600)
Payments of debt issuance costs	0	(826)	(560)	0
Payment of contingent consideration for business acquisitions	(795)	(2,277)	(560)	(3,147)
Purchases of treasury stock	(9,000)	0	(15,923)	0
Taxes paid related to net share settlement of share-based awards	(2,323)	(2,185)	(1,647)	(1,091)
Excess tax benefit from share-based compensation	568	0	0	(170)
Proceeds from the exercise of stock options	604	273	275	543
Net cash provided by (used in) financing activities	(12,869)	113,969	53,045	(40,378)
Effect of exchange rate changes on cash and cash equivalents	(2,050)	(2,180)	2,340	(361)
Net change in cash and cash equivalents	(2,034)	(1,997)	8,387	10,633
Cash and cash equivalents:
Beginning of period	21,188	27,541	19,154	10,555
End of period	19,154	25,544	27,541	21,188
Supplemental disclosure of cash paid
Interest	2,079	7,751	4,264	4,151
Income taxes	8,119	10,983	3,063	10,686
Noncash investing and financing
Equipment acquired through capital lease obligations	1,829	4,845	3,185	8,248
Issuance of notes payable and other debt obligations primarily related to acquisitions	$ 325	$ 0	$ 0	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies and Practices	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies and Practices	Summary of Significant Accounting Policies and Practices 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. Principles of Consolidation The accompanying audited 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 consolidated balance sheets. The non-controlling interests in net income, net of tax, is classified separately in the accompanying consolidated statements of income. All significant intercompany accounts and transactions have been eliminated in consolidation. On January 3, 2017, the Company's Board of Directors approved a change in the Company's fiscal year from May 31 to December 31, effective December 31, 2016. In connection with this change, the Company previously filed a Transition Report on Form 10-K to report the results of the seven-month transition period from June 1, 2016 to December 31, 2016. In this Annual Report, the periods presented are the years ended December 31, 2018 and 2017, the seven-month transition period from June 1, 2016 to December 31, 2016 and the year ended May 31, 2016. The Company has also included unaudited data for the year ended December 31, 2016 and for the seven months ended December 31, 2015 (See Note 21). For fiscal 2016, Mistras Group, Inc.’s and its subsidiaries’ fiscal years ended on May 31 except for the subsidiaries in the International segment, which ended on April 30. Accordingly, the Company’s International segment subsidiaries were consolidated on a one -month lag. Therefore, in the quarter and year of acquisition, results of acquired subsidiaries in the International segment were generally included in consolidated results for one less month than the actual number of months from the acquisition date to the end of the reporting period. Effective December 31, 2016, the Company's International segment is no longer consolidated on a one month lag, and such change for the seven month transition period ended December 31, 2016 was not material. Reclassifications 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. Use of Estimates The preparation of financial statements in accordance with U.S. generally accepted accounting principles (GAAP) requires that the Company make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses and disclosure of contingent assets and liabilities at the date of financial statements. The Company bases its estimates and assumptions on historical experience, known or expected trends and various other assumptions that it believes to be reasonable. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates, which may cause the Company’s future results to be significantly affected. Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Accounts Receivable Accounts receivable are stated net of an allowance for doubtful accounts and sales allowances. Outstanding accounts receivable balances are reviewed periodically, and allowances are provided at such time that management believes it is probable that such balances will not be collected within a reasonable period of time, to the extent reasonably estimable. The Company extends credit to its customers based upon credit evaluations in the normal course of business, primarily with 30-day terms. Bad debts are provided for based on historical experience and management’s evaluation of outstanding accounts receivable. Accounts are written off when they are deemed uncollectible under GAAP accounting standards. Concentration of Credit Risk No customer accounted for 10% or more of our revenues for the year ended December 31, 2018. One customer accounted for 11% and 12% of our revenues for the year ended December 31, 2017 and the transition period ended December 31, 2016, which primarily were generated from the Services segment. One customer accounted for 10% of our revenues in fiscal 2016 , which primarily were generated from the Services segment. Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and accounts receivable. At times, cash deposits may exceed the limits insured by the Federal Deposit Insurance Corporation. The Company believes it is not exposed to any significant credit risk or risk of nonperformance of financial institutions. Inventories Inventories are stated at the lower of cost, as determined by using the first-in, first-out method, or market. Work in process and finished goods inventory include material, direct labor, variable costs and overhead. Purchased and Internal-Use Software The Company capitalizes certain costs that are incurred to purchase or to create and implement internal-use software, which includes software coding, installation and testing. Capitalized costs are amortized on a straight-line basis over three years , the estimated useful life of the software. Property, Plant and Equipment Property, plant and equipment are recorded at cost. Depreciation of property, plant and equipment is computed utilizing the straight-line method over the estimated useful lives of the assets. Amortization of leasehold improvements is computed utilizing the straight-line method over the shorter of the remaining lease term or estimated useful life. Repairs and maintenance costs are expensed as incurred. Goodwill Goodwill represents the excess purchase price of acquired businesses over the fair values attributed to underlying net tangible assets and identifiable intangible assets. The Company tests goodwill for impairment at a “reporting unit” level (which for the Company is represented by (i) our Services segment, (ii) our Products and Systems segment, and (iii) the European component and (iv) Brazilian component of our International segment). Our annual impairment test is conducted on the first day of our fourth quarter, which is October 1. Goodwill is also tested for impairment whenever an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. During the third quarter of 2017, there was a triggering event in the Products and Systems segment that resulted in a $13.2 million goodwill impairment charge. See Note 8 for further details. If the fair value of a reporting unit is less than its carrying value, this is an indicator that the goodwill assigned to that reporting unit may be impaired. As a result of the Company adopting ASU 2017-04, impairment will be recorded in the amount that fair value is less than carrying value, as the ASU eliminated step two of the goodwill impairment process. The Company considers the income and market approaches to estimating the fair value of our reporting units, which requires significant judgment in evaluation of economic and industry trends, estimated future cash flows, discount rates and other factors. Impairment of Long-lived Assets The Company reviews the recoverability of its long-lived assets (or asset groups) on a periodic basis in order to identify indicators of a possible impairment. The assessment for potential impairment is based primarily on the Company’s ability to recover the carrying value of its long-lived assets from expected future undiscounted cash flows. If the total expected future undiscounted cash flows are less than the carrying amount of the assets, a loss is recognized for the difference between fair value (computed based upon the expected future discounted cash flows) and the carrying value of the assets. During the third quarter of 2017, there was a triggering event in the Products and Systems segment that resulted in a $2.6 million impairment charge of long-lived assets. See Note 9 for further details. Acquisitions The Company allocates the purchase price of acquired businesses to their identifiable tangible assets and liabilities as well as identifiable intangible assets, such as customer relationships, technology, non-compete agreements and trade names. Certain estimates and judgments are required in the application of the fair value techniques, including estimates of the respective acquisition's future performance and related cash flows, selection of a discount rate and economic lives, and use of Level 3 measurements as defined in Accounting Standards Update ("ASC") 820 Fair Value Measurements and Disclosure. Deferred taxes are recorded for any differences between the assigned values and tax bases of assets and liabilities. Research and Engineering Research and product development costs are expensed as incurred. Advertising, Promotions and Marketing The costs for advertising, promotion and marketing programs are expensed as incurred and are included in selling, general and administrative expenses. Advertising expense was approximately $2.1 million , $1.9 million , $1.2 million and $1.8 million for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and fiscal 2016, respectively. Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and other financial current assets and liabilities approximate fair value based on the short-term nature of the items. Foreign Currency Translation The financial position and results of operations of the Company’s foreign subsidiaries are measured using their functional currencies, which are their local currencies. Assets and liabilities of foreign subsidiaries are translated into the U.S. Dollar at the exchange rates in effect at the balance sheet date. Income and expenses are translated at the average exchange rate during the period. Translation gains and losses are reported as a component of other comprehensive (loss) income for the period and included in accumulated other comprehensive (loss) income within stockholders’ equity. Foreign currency (gains) and losses arising from transactions denominated in currencies other than the functional currency are included in net income, reported in SG&A expenses, and were approximately $1.3 million , $0.6 million , $(0.7) million and $(0.1) million for the years ended December 31, 2018 and 2017, transition period ended December 31, 2016 and fiscal 2016 , respectively. Self-Insurance The Company is self-insured for certain losses relating to workers’ compensation and health benefit claims. The Company maintains third-party excess insurance coverage for all workers' compensation and health benefit claims in excess of approximately $0.3 million per occurence to reduce its exposure from such claims. Self-insured losses are accrued when it is probable that an uninsured claim has been incurred but not reported and the amount of the loss can be reasonably estimated at the balance sheet date. Share-based Compensation The value of services received from employees and directors in exchange for an award of an equity instrument is measured based on the grant-date fair value of the award. Such value is recognized as a non-cash expense on a straight-line basis over the period the individual provides services, which is typically the vesting period of the award with the exception of awards with graded vesting that contain an internal performance measure where each tranche is recognized on a straight-line basis over its vesting period subject to the probability of meeting the performance requirements and adjusted for the number of shares expected to be earned. As share-based compensation expense is based on awards ultimately expected to vest, the amount of expense is reduced for estimated forfeitures. The cost of these awards is recorded in selling, general and administrative expense in the Company’s consolidated statements of income. Income Taxes Income taxes are accounted for under the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and tax credit carry-forwards. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred income tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is provided if it is more likely than not that some or all of a deferred income tax asset will not be realized. Financial accounting standards prescribe a minimum recognition threshold a tax position is required to meet before being recognized in the financial statements. These standards also provide guidance on de-recognition, measurement, and classification of amounts relating to uncertain tax positions, accounting for and disclosure of interest and penalties, accounting in interim periods and disclosures required. Interest and penalties related to unrecognized tax positions are recognized as incurred within “provision for income taxes” in the consolidated statements of income. 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 ASUs 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. The Company's additional required disclosures under Topic 606 are disclosed in Note 2. 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. 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. ASC 842 also requires expanded financial statement disclosures on leasing activities. These changes will become effective for the Company on January 1, 2019. The Company’s cross-functional team has determined the scope of arrangements that will be subject to this standard and continues to evaluate the impact of Topic 842 and its impacts on the Company’s business processes, systems and internal controls. The Company’s lease portfolio primarily includes buildings, machinery and equipment, vehicles and computer equipment. In adopting ASC 842, the new standard provides for several optional practical expedients in transition. The Company will adopt ASC 842 using the following practical expedients: • The optional transition method set forth in ASU 2018-11 in connection with the adoption of ASC 842 on January 1, 2019. • The “package of practical expedients,” which permits the Company not to reassess under the new standard prior conclusions on lease identification, lease classification and initial direct costs. • The practical expedient not to separate lease and non-lease components within the lease and account for all lease components as a single lease component. The Company has estimated the impact of a right-to-use asset and liability on the consolidated balance sheet related to operating leases of between $35 million and $40 million , while the accounting for capital leases will remain unchanged. The adoption of ASC 842 is not expected to result in significant impacts to our statements of income or cash flows. 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 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 their 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 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 periods 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 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 December 31, 2018, the Company has completed the accounting for the tax effects of all of the provisions of the Tax Act. (See Note 14 for further details.)

Revenue

Revenue	12 Months Ended
	Dec. 31, 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 consolidated financial statements, other than the new disclosure requirements below. 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: Year ended December 31, 2018 Services International Products Corp/Elim Total Oil & Gas $ 378,904 $ 37,953 $ 1,255 $ — $ 418,112 Aerospace & Defense 50,500 54,853 2,355 — 107,708 Industrials 60,594 26,209 3,097 — 89,900 Power generation & Transmission 30,687 8,522 4,904 — 44,113 Other Process Industries 26,425 9,497 124 — 36,046 Infrastructure, Research & Engineering 11,283 9,032 5,246 — 25,561 Other 16,226 7,382 6,445 (9,139 ) 20,914 Total $ 574,619 $ 153,448 $ 23,426 $ (9,139 ) $ 742,354 Revenue per key geographic location was as follows: Year ended December 31, 2018 Services International Products Corp/Elim Total United States $ 478,853 $ 568 $ 11,493 $ (3,500 ) $ 487,414 Other Americas 90,823 7,995 1,068 (1,638 ) 98,248 Europe 4,252 138,948 3,958 (3,846 ) 143,312 Asia-Pacific 691 5,937 6,907 (155 ) 13,380 Total $ 574,619 $ 153,448 $ 23,426 $ (9,139 ) $ 742,354 Contract Balances The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits (contract liabilities) on the consolidated balance 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 receives 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 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 $5.3 million . Changes in the contract asset and liability balances during the year ended December 31, 2018, were not impacted by any other factors. The Company has elected to utilize a practical expedient to expense incremental costs incurred related to obtaining a contract.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share Basic earnings per share is computed by dividing net income attributable to common shareholders by the weighted average number of shares outstanding during the period. Diluted earnings per share is computed by dividing net income attributable to common shareholders 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) only 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: For the year ended December 31, For the transition period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Basic earnings (loss) per share Numerator: Net income (loss) attributable to Mistras Group, Inc. $ 6,836 $ (2,175 ) $ 9,568 $ 24,654 Denominator Weighted average common shares outstanding 28,406 28,422 28,989 28,856 Basic earnings (loss) per share $ 0.24 $ (0.08 ) $ 0.33 $ 0.85 Diluted earnings (loss) per share: Numerator: Net income (loss) attributable to Mistras Group, Inc. $ 6,836 $ (2,175 ) $ 9,568 $ 24,654 Denominator Weighted average common shares outstanding 28,406 28,422 28,989 28,856 Dilutive effect of stock options outstanding 683 — 791 712 Dilutive effect of restricted stock units outstanding 338 — 345 323 29,427 28,422 30,125 29,891 Diluted earnings (loss) per share $ 0.23 $ (0.08 ) $ 0.32 $ 0.82 The following potential common shares were excluded from the computation of diluted earnings per share, as the effect would have been anti-dilutive: For the year ended December 31, For the transition period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Potential common stock attributable to stock options outstanding 5 810 (1 ) — 5 Potential common stock attributable to restricted stock units (RSUs) and performance stock units (PSUs) outstanding 1 353 (2 ) 2 24 Total 6 1,163 2 29 (1) - 805 shares related to stock options were excluded from the calculation of diluted EPS due to the net loss for the period. (2) - 351 shares related to RSUs and PSUs were excluded from the calculation of diluted EPS due to the net loss for the period.

Accounts Receivable, net

Accounts Receivable, net	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Accounts Receivable, net	Accounts Receivable, net Accounts receivable consist of the following: December 31, December 31, 2018 2017 Trade accounts receivable $ 152,511 $ 141,952 Allowance for doubtful accounts (4,187 ) (3,872 ) Accounts receivable, net $ 148,324 $ 138,080 The Company had $16.1 million and $14.4 million of unbilled revenues accrued as of December 31, 2018 and December 31, 2017, respectively, which is included within the trade accounts receivable balance above. Unbilled revenues as of December 31, 2018 are expected to be billed in the first quarter of 2019 . As of December 31, 2018, the Company’s Services Division had $5.6 million of accounts receivables due from one customer for services provided in North America. This customer has been having cash flow issues recently attributable to a working capital deterioration and the accounts receivable balance was beginning to age as of December 31, 2018. After the end of 2018, the customer expressed to the Company its desire to establish a payment plan that would pay in full all amounts due to the Company before the end of 2019. The Company has established a reserve of approximately 12% of the receivable balance based upon available information about the customer, the timing and likelihood of expected payments, and the Company’s historical reserve experience. The Company will continue to monitor the account and assess any change in circumstances, including any failure to meet the payment plan which may result in the need for additional reserves.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: December 31, December 31, 2018 2017 Raw materials $ 6,975 $ 5,105 Work in progress 1,019 1,192 Finished goods 2,640 2,746 Consumable supplies 2,419 1,460 Inventory $ 13,053 $ 10,503

Property, Plant and Equipment,

Property, Plant and Equipment, net	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, net	Property, Plant and Equipment, net Property, plant and equipment consist of the following: December 31, December 31, Useful Life 2018 2017 (Years) Land $ 2,680 $ 2,414 Building and improvements 30-40 24,338 24,003 Office furniture and equipment 5-8 16,170 14,230 Machinery and equipment 5-7 208,245 191,721 251,433 232,368 Accumulated depreciation and amortization (157,538 ) (145,225 ) Property, plant and equipment, net $ 93,895 $ 87,143 Depreciation expense was approximately $24.2 million , $22.4 million , $14.0 million and $22.9 million for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and fiscal 2016, respectively.

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions Acquisitions During the year ended December 31, 2018, the Company completed one acquisition that performs inline inspection services, with headquarters in Canada and a location in the U.S. The acquired company primarily provides services to the midstream area within the oil and gas industry. In this acquisition, the Company acquired 100% of the equity interests of the Canadian and U.S. entities in exchange for aggregate consideration of $143.1 million in cash. During the year ended December 31, 2017, the Company completed three acquisitions, one that performs mechanical services at height, located in Canada, a company located in the U.S. that primarily performs chemical and specialty process services and a company in the U.S. that performs a wide variety of non-destructive testing services. Both U.S. companies primarily provide services to the aerospace industry. In these acquisitions, the Company acquired 100% of the equity interests of the entity based in Canada and one of the entities based in the U.S. in exchange for aggregate consideration of $79.5 million in cash, contingent consideration up to $2.4 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 $0.2 million for working capital adjustments that were finalized during 2018. The Company acquired the assets of one of the U.S. based entities noted above in exchange for aggregate consideration of $4.5 million in cash and contingent consideration up to $3.5 million to be earned based upon the acquired business achieving specific performance metrics over the initial three years of operations from the acquisition date. The Company accounted for these transactions in accordance with the acquisition method of accounting for business combinations. Assets and liabilities of the acquired businesses were included in the consolidated balance sheet as of December 31, 2018 and December 31, 2017 based on their respective estimated fair value on the date of acquisition as determined in a purchase price allocation, using available information and making assumptions management believes are reasonable. The Company is still in the process of completing its valuation of the assets, both tangible and intangible, and liabilities acquired for the acquisition completed during the year ended December 31, 2018. Goodwill of $83.2 million primarily relates to expected synergies and assembled workforce, which is no t deductible for tax purposes. Other intangible assets, primarily related to technology, customer relationships and covenants not to compete, were $59.6 million . The results of operations of each of the acquisitions completed during the years ended December 31, 2018 and 2017 are included in each respective operating segment’s results of operations from the date of acquisition. The following table summarizes the estimated fair value of the assets acquired and liabilities assumed, the Company's allocation of purchase price and any subsequent adjustments made during the years ended December 31, 2018 and 2017: Year ended December 31, 2018 Year ended December 31, 2017 Number of entities 1 3 Cash paid $ 143,139 $ 83,963 Working capital adjustments — 150 Notes payable — — Contingent consideration — 3,407 Consideration paid $ 143,139 $ 87,520 Current net assets $ 9,381 $ 7,165 Other assets 136 — Debt and other liabilities (4,976 ) (2,848 ) Property, plant and equipment 8,549 11,115 Deferred tax liability (12,672 ) (1,278 ) Intangibles 59,558 31,671 Goodwill 83,163 41,695 Net assets acquired $ 143,139 $ 87,520 The amortization period for intangible assets acquired ranges from two to fourteen years . The Company recorded $83.2 million and $41.7 million of goodwill in connection with its acquisitions for the years ended December 31, 2018 and 2017, respectively, reflecting the strategic fit and revenue and earnings growth potential of these businesses. For the period subsequent to the closing of the transaction, revenue included in the consolidated statement of income for the year ended December 31, 2018 from the business acquired in 2018 was approximately $0.3 million and is included in the Services segment from the date of acquisition. Aggregate loss from operations included in the consolidated statement of income for the year ended December 31, 2018 from this acquisition for the period subsequent to the closing of the transaction was $2.0 million , inclusive of $1.3 million of acquisition-related expense. 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 that was paid December 2018. For the year ended December 31, 2018, the Company recognized a gain of approximately $2.4 million related to the sale, which is included in its own line on the 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 , of which $2.1 million is remaining as of December 31, 2018. 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 year ended December 31, 2018. The Company determined that the classification of being held for sale has been met as of December 31, 2017. For the year ended December 31, 2017, this subsidiary represented 0.6% of consolidated revenues and loss from operations was $3.5 million , inclusive of a $2.6 million impairment charge for long-lived assets (See Note 9). In the aggregate, the assets and liabilities of this subsidiary represent 0.4% and 0.2% of consolidated assets and liabilities, respectively, and are included in their natural classifications on the 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 (benefit) expense, net, on the consolidated statements of income and were as follows for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and fiscal 2016: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Due diligence, professional fees and other transaction costs $ 1,248 $ 945 $ 231 $ 629 Adjustments to fair value of contingent consideration liabilities (716 ) (463 ) 265 (2,082 ) Acquisition-related (benefit) expense, net $ 532 $ 482 $ 496 $ (1,453 ) The Company’s contingent consideration liabilities are recorded on the balance sheet in accrued expenses and other liabilities. Unaudited Pro Forma Financial Information The following table provides unaudited pro forma financial information for the years ended December 31, 2018 and 2017 as if the acquisition of Onstream had occurred on January 1, 2017. (Information in thousands, except per share data). For the year ended December 31, 2018 2017 Total revenue $ 770,222 $ 727,821 Net income (loss) 6,602 (2,180 ) Net income (loss) per common share: basic $ 0.23 $ (0.08 ) Net income (loss) per common share: diluted $ 0.22 $ (0.08 ) The unaudited pro forma financial information was prepared using the acquisition method of accounting and was based on the historical financial information of Mistras and Onstream. The supplemental pro forma financial information reflects primarily the following pro forma adjustments: • The pro forma financial information assumes that the acquisition related transaction fees and costs for Onstream were removed from the year ended December 31, 2018 and were assumed to have been incurred prior to acquisition; • Additional interest expense resulting from the issuance of debt to finance the consideration exchanged for the acquisition. • Additional depreciation and amortization expense due to (1) the amortization of identifiable intangibles with a definitive life using the straight-line method over a weighted average useful life of 12.6 years , and (2) increase in depreciation resulting from the step-up of property, plant and equipment depreciated on a straight-line basis over their useful life of 5 years ; and • Adjustments were tax effected at an effective tax rate of 26% as of December 31, 2018 and 31% as of December 31, 2017. The unaudited pro forma results do not reflect any operating efficiencies or potential cost savings that may result from the combined operations of Mistras and Onstream. Accordingly, these unaudited pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual results of operations of the combined company that would have been achieved.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill The changes in the carrying amount of goodwill by segment is shown below: Services International Products and Systems Total Balance at December 31, 2016 $ 123,392 $ 33,351 $ 13,197 $ 169,940 Goodwill acquired during the year 41,695 — — 41,695 Impairment charge — — (13,197 ) (13,197 ) Adjustments to preliminary purchase price allocations (211 ) — — (211 ) Foreign currency translation 925 4,286 — 5,211 Balance at December 31, 2017 $ 165,801 $ 37,637 $ — $ 203,438 Goodwill acquired during the year 83,163 — — 83,163 Adjustments to preliminary purchase price allocations (1,977 ) — — (1,977 ) Foreign currency translation (3,511 ) (1,854 ) — (5,365 ) Balance at December 31, 2018 $ 243,476 $ 35,783 $ — $ 279,259 During the second quarter of 2017, there were pending Products and Systems contract bids which management assessed as having a reasonable chance of success. During the third quarter of 2017, these contract bids were not awarded to the Company. As a result of this missed opportunity, the annual forecasting process was accelerated, resulting in lower expected future operating profits and cash flows. As such, during the third quarter of 2017, there were indicators that the carrying amount of the goodwill for the Products and Systems reporting unit may not have been recoverable due to the decline in the projected future cash flows. Due to the above, the Company performed an analysis to determine any impairment of goodwill as well as long-lived assets (see Note 9). For the goodwill analysis, the Company used income and market approaches to estimate the fair value of the reporting unit, which required significant judgment in evaluation of economic and industry trends, estimated future cash flows, discount rates and other factors, and compared that fair value to the carrying value, and determined that the fair value of the reporting unit was less than the carrying value. The Company recorded an impairment charge of $13.2 million , based on the difference between the fair value and the carrying value of the reporting unit, which resulted in an impairment of the entire amount of goodwill for the Products and Systems reporting unit. The Company performed an impairment test of its remaining reporting units as of October 1, 2018 and concluded that there was no impairment. F or the year ended December 31, 2018, the Company reviewed goodwill for impairment on a reporting unit basis. As of December 31, 2018 , the Company did not identify any changes in circumstances that would indicate the remaining carrying value of goodwill may not be recoverable. The Company's cumulative goodwill impairment as of December 31, 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	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets The gross carrying amount and accumulated amortization of intangible assets were as follows: December 31, December 31, 2018 2017 Useful Life (Years) Gross Accumulated Net Gross Accumulated Impairment Net Customer relationships 5-14 $ 112,624 $ (60,993 ) $ 51,631 $ 113,299 $ (58,107 ) $ (170 ) $ 55,022 Software/Technology 3-15 67,240 (13,319 ) 53,921 19,523 (14,133 ) (2,411 ) 2,979 Covenants not to compete 2-5 12,593 (10,825 ) 1,768 12,510 (10,438 ) — 2,072 Other 2-12 10,317 (6,242 ) 4,075 10,109 (6,411 ) (32 ) 3,666 Total $ 202,774 $ (91,379 ) $ 111,395 $ 155,441 $ (89,089 ) $ (2,613 ) $ 63,739 Amortization expense for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016 was approximately $10.2 million , $9.0 million , $5.2 million and $9.6 million , respectively, including amortization of software/technology for these periods of $1.4 million , $1.2 million , $0.5 million and $1.0 million , respectively. As described in Note 8, in 2017 the Company performed an analysis to determine whether there was any impairment of long-lived assets for the Products and Systems reporting unit. The Company used income and market approaches to estimate the fair value of the long-lived assets, which requires significant judgment in evaluation of the useful lives of the assets, economic and industry trends, estimated future cash flows, discount rates, and other factors. The result of the analysis was an impairment of $2.4 million to software/technology, $0.2 million to customer relationships and less than $0.1 million to other intangibles, which are included in the impairment charges line on the consolidated statements of income for the year ended December 31, 2017. Amortization expense in each of the five years and thereafter subsequent to December 31, 2018 related to the Company’s intangible assets is expected to be as follows: Expected Amortization Expense 2019 $ 13,735 2020 12,368 2021 11,292 2022 10,722 2023 9,946 Thereafter 53,332 Total $ 111,395

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following: December 31, 2018 2017 Accrued salaries, wages and related employee benefits $ 29,959 $ 27,185 Contingent consideration 1,687 3,430 Accrued workers' compensation and health benefits 5,086 5,181 Deferred revenues 5,046 6,338 Legal settlement accrual — 1,600 Pension accrual 5,585 — Other accrued expenses 26,532 21,827 Total accrued expenses and other current liabilities $ 73,895 $ 65,561

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Long-term debt consists of the following: December 31, 2018 2017 Senior credit facility $ 181,656 $ 156,948 Senior secured term loan, net of debt issuance costs of $0.1 million 99,897 — Notes payable 68 228 Other 8,999 9,702 Total debt 290,620 166,878 Less: Current portion (6,833 ) (2,358 ) Long-term debt, net of current portion $ 283,787 $ 164,520 Senior Credit Facility On December 13, 2018, the Company entered into a Fifth Amended and Restated Credit Agreement (“Credit Agreement”). The Credit Agreement increased the Company’s revolving line of credit from $250 million to $300 million and provides that under certain circumstances the line of credit can be increased to $450 million . In addition, the Credit Agreement provided the Company with a $100 million senior secured term loan A facility. Both the revolving line of credit and the term loan A facility under the Credit Agreement have a maturity date of December 12, 2023. The Company may continue to borrow up to $100 million in non-U.S. Dollar currencies and use up to $20 million of the credit limit for the issuance of letters of credit. At December 31, 2018 , the Company had borrowings of $281.7 million and letters of credit of $5.4 million were outstanding under the Credit Agreement. The Company has capitalized costs of $1.1 million associated with debt modifications as of December 31, 2018, included in other long-term assets within the accompanying consolidated balance sheet. Loans under the Credit Agreement bear interest at 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 generally 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 $10 million in the four consecutive quarters immediately preceding the date of determination) for items such as severance, lease termination charges, asset write-offs and litigation settlements paid, and multi-employer pension plan withdrawal liabilities, all determined for the period of four consecutive fiscal quarters immediately preceding the date of determination of EBITDA. The Company has the benefit of the lowest margin if its Funded Debt Leverage Ratio is equal to or less than 1.0 to 1, and the margin increases as the ratio increases, to the maximum margin if the ratio is greater than 3.25 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 4.25 to 1 through December 31, 2018, reducing to a maximum permitted ratio of 3.50 to 1 as of March 31, 2020 and all quarterly periods thereafter, and a Fixed Charge Coverage Ratio of at least 1.25 to 1. Fixed Charge Coverage Ratio means the ratio, as of any date of determination, of (a) (i) EBITDA for the 12 month period immediately preceding the date of determination, taken together as one accounting period, less (ii) the aggregate amount of all capital expenditures made during the period, less (iii) taxes paid in cash during the period, less (iv) Restricted Payments (as defined in the Credit Agreement) paid in cash during the period, -to- (b) the sum of (i) all interest, premium payments, debt discount, fees, charges and related expenses of us and our 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 U.S. generally accepted accounting principles ("GAAP") and to the extent paid in cash during the period, (ii) the aggregate principal amount of all redemptions or similar acquisitions for value of outstanding debt for borrowed money or regularly scheduled principal payments made during the period, but excluding any such payments to the extent refinanced through the incurrence of additional Indebtedness otherwise expressly permitted under the Credit Agreement, and (iii) payments made during the period under all leases that have been or should be, in accordance with GAAP as in effect for the Company's 2017 audited financial statement, recorded as capitalized leases. Beginning in 2020, the Company can elect to increase the maximum Funded Debt Leverage Ratio to 4.0 to 1 for four fiscal quarters immediately following the fiscal quarter in which the Company acquires another business, with the maximum permitted ratio reducing back to 3.5 to 1 in the fifth fiscal quarter following such acquisition. 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 and a pledge of its stock. As of December 31, 2018 , the Company was in compliance with the terms of the Credit Agreement, and has undertaken to continuously monitor compliance with these covenants. Notes Payable and Other Debt 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, expiring through 2019, and bear interest at the prime rate for the Bank of Canada, currently 3.95% as of December 31, 2018. Interest expense is recorded in the 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 December 31, 2018, there was approximately $9.0 million outstanding, payable at various times from 2019 to 2029. Monthly payments range from $1 thousand to $17 thousand . Interest rates range from 0.6% to 6.2% . Scheduled principal payments due under all borrowing agreements in each of the five years and thereafter subsequent to December 31, 2018 are as follows: 2019 $ 6,831 2020 6,515 2021 8,750 2022 11,030 2023 255,043 Thereafter 2,451 Total $ 290,620

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 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. It also establishes a three level hierarchy that prioritizes the inputs used to measure fair value. The three levels of the hierarchy are defined as follows: Level 1 — Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 — Observable inputs other than quoted prices included in Level 1, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability and inputs derived principally from or corroborated by observable market data. Level 3 — Unobservable inputs reflecting the Company’s own assumptions about inputs that market participants would use in pricing the asset or liability based on the best information available. 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: Balance at December 31, 2016 $ 3,094 Acquisitions 3,407 Payments (560 ) Accretion of liability 272 Revaluation (735 ) Foreign currency translation 30 Balance at December 31, 2017 $ 5,508 Acquisitions — Payments (2,277 ) Accretion of liability 175 Revaluation (891 ) Foreign currency translation (150 ) Balance at December 31, 2018 $ 2,365 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.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 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 Directors under three employee stock ownership 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. No further awards may be granted under either the 2007 Plan or the 2009 Plan, although awards granted under the 2007 Plan and 2009 Plan 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. The 2016 Plan allows for the grant of awards of up to approximately 1,700,000 shares of common stock, of which 1,143,000 shares were available for future grants as of December 31, 2018 . As of December 31, 2018 , there was an aggregate of approximately 2,105,000 stock options outstanding and approximately 452,000 unvested restricted stock units outstanding under the 2009 Plan and the 2007 Plan. Stock Options For the years ended December 31, 2018 and 2017 and the transition period ended December 31, 2016, the Company did no t have any share-based compensation expense related to stock option awards. For the year ended May 31, 2016, the Company recognized share-based compensation expense related to stock option awards of less than $0.1 million . No stock options were granted during the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 or the year ended May 31, 2016. As of December 31, 2018 , no unrecognized compensation costs remained related to stock option awards. Cash proceeds from, and the intrinsic value of, stock options exercised during the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016 were as follows: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Cash proceeds from options exercised $ 273 $ 275 $ 604 $ 543 Aggregate intrinsic value of options exercised 277 580 993 658 A summary of the stock option activity, weighted average exercise prices, and options outstanding and exercisable as of December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016 is as follows (in thousands, except per share amounts): For the years ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Common Stock Options Weighted Average Exercise Price Common Weighted Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Outstanding at beginning of year: 2,130 $ 13.43 2,167 $ 13.33 2,232 $ 13.21 2,287 $ 13.13 Granted — $ — — $ — — $ — — $ — Exercised (25 ) $ 10.75 (37 ) $ 7.39 (65 ) $ 9.27 (55 ) $ 9.87 Expired or forfeited — $ — — $ — — $ — — $ — Outstanding at end of year: 2,105 $ 13.47 2,130 $ 13.43 2,167 $ 13.33 2,232 $ 13.21 For the year ended December 31, 2018 Options Outstanding Options Exercisable Range of Exercise Prices Total Options Outstanding Weighted Average Remaining Life (Years) Weighted Average Exercise Price Number Exercisable Weighted Average Exercise Price $10.00-$10.00 10 0.3 $ 10.00 10 $ 10.00 $13.46-$22.35 2,095 0.7 $ 13.48 2,095 $ 13.48 2,105 2,105 Aggregate Intrinsic Value $ 1,965 $ 1,965 Restricted Stock Unit Awards Restricted Stock Units generally vest ratably on each of the first four anniversary dates of issuance. The Company recognized approximately $4.2 million and $4.5 million of share-based compensation for the years ended December 31, 2018 and 2017, $2.6 million of share-based compensation for the transition period ended December 31, 2016 and $4.4 million of share-based compensation in fiscal 2016 related to restricted stock unit awards. As of December 31, 2018 , there were approximately $6.8 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 2.4 years . A summary of the vesting activity of restricted stock unit awards, with the respective fair value of the awards, is as follows: (awards in thousands, fair value in millions): For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Restricted stock awards vested 258 185 207 223 Fair value of awards vested $ 5.3 $ 3.4 $ 5.1 $ 3.5 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 fully-vested common stock the Company issued to its five non-employee directors, in connection with its non-employee director compensation plan, is as follows: (awards in thousands, fair value in millions) For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Awards issued 19 21 10 28 Grant date fair value of awards issued $ 0.4 $ 0.4 $ 0.3 $ 0.5 A summary of the Company's outstanding, non-vested restricted share units is presented below: For the year ended December 31, For the transition period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Units Weighted Units Weighted Units Weighted Units Weighted Average Grant-Date Fair Value Outstanding at beginning of period: 532 $ 21.05 569 $ 20.81 575 $ 18.85 564 $ 20.47 Granted 211 $ 19.20 183 $ 21.26 219 $ 24.48 264 $ 16.73 Released (258 ) $ 20.48 (185 ) $ 20.49 (207 ) $ 19.40 (223 ) $ 20.40 Forfeited (42 ) $ 20.52 (35 ) $ 21.45 (18 ) $ 19.55 (30 ) $ 19.26 Outstanding at end of period: 443 $ 20.55 532 $ 21.05 569 $ 20.81 575 $ 18.85 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 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. Cumulative 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 year ended December 31, For the transition period ended December 31, 2018 2017 2016 Units Weighted Units Weighted Units Weighted Outstanding at beginning of period: 278 $ 17.00 290 $ 16.01 328 $ 17.02 Granted 129 $ 19.46 128 $ 20.42 105 $ 24.90 Performance condition adjustments, net (50 ) $ 19.48 (68 ) $ 20.55 (54 ) $ 24.49 Released (68 ) $ 16.03 (72 ) $ 15.82 (89 ) $ 24.50 Forfeited (12 ) $ 16.16 — $ — — $ — Outstanding at end of period: 277 $ 17.80 278 $ 17.00 290 $ 16.01 In fiscal 2014 , the Company granted one -year, two -year and three -year PRSUs to its executive and certain other senior officers. These units had requisite service periods of three years and have no dividend rights. The actual payout of these units, before the fiscal 2016 modification as described below, was based on the Company’s performance over one, two and three-year periods (based on pre-established targets) and a market condition modifier based on total shareholder return (TSR) compared to an industry peer group. The one -year and two -year performance conditions of the fiscal 2014 awards were evaluated before modification of the awards and not achieved. The one -year and two -year market conditions of the fiscal 2014 awards were evaluated before modification of the awards and achieved. Compensation costs related to the TSR conditions for the one-year and two-year 2014 awards described above were fixed at the measurement date, and not subsequently adjusted. The one -year and two -year awards related to market conditions were paid at 170% and 105% , respectively, of target, upon vesting during the transition period ended December 31, 2016. The three -year performance and market condition awards were surrendered as part of the fiscal 2016 modification described below. In fiscal 2015 , the Company granted PRSUs to its executive and certain other senior officers. These units have requisite service periods of three years and have no dividend rights. The actual payout of these units, before the fiscal 2016 modification as described below, was based on the Company’s performance over the three -year period (based on pre-established targets) and a market condition modifier based on (TSR) compared to an industry peer group. The 2015 awards were surrendered as part of the fiscal 2016 modification described below. In the first quarter of fiscal 2016, the Company modified its equity compensation program and granted 154,000 PRSUs to its executive and certain other senior officers. As a condition for receiving any awards under the revised fiscal 2016 plan, the executive and senior officers surrendered and released all rights to receive any shares under the three -year 2014 awards and three -year 2015 awards with a performance or market condition. The Company has accounted for the fiscal 2016 awards as modifications in accordance with ASC 718, Compensation - Stock Compensation. These units have requisite service periods of five years and have no dividend rights. The fiscal 2016 PRSUs increased by approximately 104,000 units to a total of 258,000 units, which represents Company performance above target as well as individual performance, and was approved by the Compensation Committee in August 2016. For the transition period ended December 31, 2016, 105,000 PRSUs were granted. There was a 73,000 unit reduction to these awards, which represents Company performance below target, during the transition period ended December 31, 2016. As of December 31, 2016, the aggregate liability related to 12,000 outstanding Discretionary PRSUs was less than $0.1 million and is classified within accrued expenses and other liabilities on the consolidated balance sheet. The Compensation Committee approved these PRSUs in the first quarter of 2017, which reduced them by 3,000 units. The discretionary portion of these awards were reclassed from a liability to equity on the consolidated balance sheet upon Compensation Committee approval. For the year ended December 31, 2017, 128,000 PRSUs were granted. There was a 65,000 unit reduction to these awards, which represents Company performance below target, during the year ended December 31, 2017. As of December 31, 2017, the aggregate liability related to 13,000 outstanding Discretionary PRSUs was less than $0.1 million and is classified within accrued expenses and other liabilities on the consolidated balance sheet. The Compensation Committee approved these PRSUs in the first quarter of 2018, which increased them by 4,000 units. The discretionary portion of these awards were reclassed from a liability to equity on the consolidated balance sheet upon Compensation Committee approval. For the year ended December 31, 2018, 129,000 PRSUs were granted. There was a 54,000 unit reduction to these awards, which represents Company performance below target, during the year ended December 31, 2018. As of December 31, 2018, the aggregate liability related to 22,000 outstanding discretionary PRSUs was less than $0.1 million and is classified within accrued expenses and other liabilities on the consolidated balance sheet. Compensation expense related to all PRSUs described above was $1.5 million , $1.7 million , $1.7 million and $1.6 million for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016, respectively. At December 31, 2018, there was $1.8 million of total unrecognized compensation costs related to approximately 309,000 nonvested performance restricted stock units. These costs are expected to be recognized over a weighted-average period of approximately 1.9 years . For the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016, the income tax benefit recognized on all share based compensation arrangements referenced above was approximately $1.0 million , $2.2 million , $1.6 million and $2.2 million , respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income before provision for income taxes is as follows: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Income (loss) before provision for income taxes from: U.S. operations $ 9,853 $ (7,303 ) $ 5,116 $ 27,772 Foreign operations 4,418 7,077 10,365 10,643 Earnings (loss) before income taxes $ 14,271 $ (226 ) $ 15,481 $ 38,415 The provision for income taxes consists of the following: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Current Federal $ 790 $ 3,558 $ 1,990 $ 9,156 States and local 533 39 483 1,537 Foreign 3,824 3,131 3,569 3,672 Reserve for uncertain tax positions 337 71 (39 ) (529 ) Total current 5,484 6,799 6,003 13,836 Deferred Federal 2,966 (3,857 ) 6 82 States and local 399 (810 ) (28 ) (51 ) Foreign (2,089 ) (437 ) (514 ) (557 ) Total deferred 1,276 (5,104 ) (536 ) (526 ) Net change in valuation allowance 666 247 403 455 Net deferred 1,942 (4,857 ) (133 ) (71 ) Provision for income taxes $ 7,426 $ 1,942 $ 5,870 $ 13,765 The provision for income taxes differs from the amount computed by applying the statutory federal tax rate to income tax as follows: For the years ended December 31, For the Transition period ended December 31, 2018 2017 2016 Federal tax at statutory rate $ 2,997 21.0 % $ (79 ) 35.0 % $ 5,418 35.0 % State taxes, net of federal benefit 737 5.1 % (502 ) 221.6 % 296 1.9 % Foreign tax 807 5.7 % 217 (95.8 )% (573 ) (3.7 )% Contingent consideration (6 ) — % (63 ) 27.7 % (4 ) — % Nondeductible compensation 183 1.3 % — — % — — % US taxation of foreign earnings 228 1.6 % — — % — — % Permanent differences 361 2.5 % 377 (166.4 )% 373 2.4 % Transition tax, net of foreign tax credits 1,158 8.1 % 3,942 (1,741.4 )% — — % Federal tax rate change due to the Tax Act 87 0.6 % (1,956 ) 864.0 % — — % Other 208 1.4 % (241 ) 106.5 % (43 ) (0.3 )% Change in valuation allowance 666 4.7 % 247 (109.1 )% 403 2.6 % Total provision for income taxes $ 7,426 52.0 % $ 1,942 (857.9 )% $ 5,870 37.9 % On December 22, 2017, the United States enacted fundamental changes to the federal tax law following the passage of the Tax Cuts and Jobs Act (the "Tax Act"). The Tax Act is complex and significantly changes the U.S. corporate tax system by, among other things, (a) reducing the federal corporate tax rate from 35% to 21% for tax years beginning after December 31, 2017, (b) replacing the prior system of taxing corporations on foreign earnings of their foreign subsidiaries when the earnings are repatriated with a partial territorial tax system that provides a 100% dividends-received deduction (DRD) to domestic corporations for foreign-sourced dividends received from 10%-or-more owned foreign corporations, (c) subjecting certain unrepatriated foreign earnings to a mandatory one-time transition tax on post-1986 earnings and profits ("the transition tax"), and (d) further limiting a public entity's ability to deduct compensation in excess of $1 million for covered employees. For the financial statements for the year ended December 31, 2017, the Company had reasonably estimated the tax effects of the Tax Act. The effect of the change in federal corporate tax rate from 35% to 21% was subject to change based on resolution of estimates used in determining the amounts of deferred tax assets and liabilities that were remeasured. The Company's calculation of the transition tax was subject to further refinement as more information was gathered from its foreign subsidiaries, estimates used in the calculation were resolved, and as states provided guidance on how the transition tax may or may not apply in their respective jurisdictions. The Company also anticipated that the deferred tax asset related to executive compensation would change based upon actual 2018 compensation as compared to its projections of compensation that were limited. Finally, the Tax Act also imposes a minimum tax on certain foreign income deemed to be in excess of a routine return based on tangible asset investment, which is designed to discourage income shifting by subjecting certain foreign intangibles and other income to current US tax. Effective for tax years beginning after 2017, US shareholders of certain foreign corporations are subject to current U.S. tax on their global intangible low-taxed income (GILTI). As of December 31, 2017, the Company had not yet evaluated its potential liability, if any, under the minimum tax for GILTI in 2018 or future years. Accordingly, the Company had not yet made an accounting policy election either to account for these effects in the future period when the tax arises or to recognize them as part of the deferred taxes. The impact on income tax expense related to the Tax Act for 2017 was $1.9 million . This amount reflects a net tax benefit of $2.3 million as a result of the Tax Act due to the remeasurement of federal deferred tax assets and liabilities from 35% to 21%. This amount also includes a charge of $3.9 million due to the transition tax. Additionally, the Company incurred a charge attributable to reducing its deferred tax assets by $0.3 million due to changes made to executive compensation rules pursuant to the Tax Act. During the year ended December 31, 2018, the Company completed its accounting for the effects of the Tax Act on the period ended December 31, 2017, which resulted in income tax expense of $1.7 million . This consisted primarily of $0.1 million of an increase in the Company's net deferred tax liabilities due to the reduction in the federal corporate rate from 35% to 21%, an increase of $1.3 million in tax expense attributable to the transition tax and a decrease in deferred tax assets of $0.4 million due to changes made to executive compensation. Additionally, the Company incurred an increase in income tax expense of $0.2 million due to GILTI, and an increase of $0.3 million due to additional non-deductible expenses. For GILTI, the Company has made an accounting policy election to account for these effects in the future period when the tax arises. For the year ended May 31, 2016 Federal tax at statutory rate $ 13,445 35.0 % State taxes, net of federal benefit 966 2.5 % Foreign tax (610 ) (1.6 )% Contingent consideration (425 ) (1.1 )% Permanent differences 245 0.6 % Other (311 ) (0.8 )% Change in valuation allowance 455 1.2 % Total provision for income taxes $ 13,765 35.8 % Deferred income tax attributes resulting from differences between financial accounting amounts and income tax basis of assets and liabilities are as follows: December 31, 2018 2017 Deferred income tax assets Allowance for doubtful accounts $ 951 $ 838 Inventory 285 265 Intangible assets 1,230 2,255 Accrued expenses 4,408 2,560 Net operating loss carryforward 3,889 3,729 Capital lease obligations 731 1,004 Capital losses 462 463 Foreign tax credit carryover — 618 Deferred share-based compensation 3,728 4,080 Other 699 484 Deferred income tax assets 16,383 16,296 Valuation allowance (4,235 ) (4,044 ) Net deferred income tax assets 12,148 12,252 Deferred income tax liabilities Property and equipment (7,597 ) (6,893 ) Goodwill (9,302 ) (6,578 ) Intangible assets (16,459 ) (5,972 ) Other (8 ) (6 ) Deferred income tax liabilities (33,366 ) (19,449 ) Net deferred income taxes $ (21,218 ) $ (7,197 ) As of December 31, 2018 , the Company had federal net operating loss carry forwards (NOLs) in the amount of approximately $0.3 million which may be utilized subject to limitation under Internal Revenue Code section 382. The federal NOLs expire at various times from 2031 to 2035. In addition, as of December 31, 2018 , the Company had state and foreign NOLs of $25.0 million and $11.0 million , respectively. The state NOLs expire at various times from 2025 to 2038. Approximately $0.8 million of the foreign NOLs expire at various times from 2025 to 2038, while the remainder of the Company's foreign NOLs do not expire. In assessing the ability to realize deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will be realized. Valuation allowances are provided when management believes the Company's deferred tax assets are not recoverable based on an assessment of estimated future taxable income that incorporates ongoing, prudent and feasible tax planning strategies. At December 31, 2018 and December 31, 2017, the Company has a valuation allowance of approximately $4.2 million and $4.0 million , respectively, primarily against certain state and foreign NOLs, capital losses generated by the disposals of certain foreign subsidiaries and other specific deferred tax assets. The increase of $0.2 million is primarily attributable to an increase against the foreign net operating losses. Except for those deferred tax assets subject to the valuation allowance, management believes that it will realize all deferred tax assets as a result of sufficient future taxable income in each tax jurisdiction in which the Company has deferred tax assets. The following table summarizes the changes in the Company’s gross unrecognized tax benefits, excluding interest and penalties: For the year ended December 31, 2018 2017 Balance at beginning of period $ 156 $ 267 Additions for tax positions related to the current fiscal period 1 11 Additions for tax positions related to prior years 341 188 Decreases for tax positions related to prior years (2 ) — Current year acquisitions 270 — Impact of foreign exchange fluctuation — 10 Settlements (4 ) (198 ) Reductions related to the expiration of statutes of limitations (39 ) (122 ) Balance at end of period $ 723 $ 156 The Company has recorded the unrecognized tax benefits in other long-term liabilities in the consolidated balance sheets. As of December 31, 2018 and December 31, 2017, there were approximately $0.7 million and $0.2 million of unrecognized tax benefits, respectively, including penalties and interest that if recognized would favorably affect the effective tax rate. Interest and penalties related to unrecognized tax benefits are recorded in income tax expense and are not significant for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016. The Company anticipates a decrease to its unrecognized tax benefits of less than $0.5 million excluding interest and penalties within the next 12 months. The Company is subject to taxation in the United States and various states and foreign jurisdictions. The Company is no longer subject to U.S. federal income tax examinations for years ending before May 31, 2016 and generally is no longer subject to state, local or foreign income tax examinations by tax authorities for years ending before May 31, 2015. Net income (loss) of foreign subsidiaries was $2.0 million , $4.1 million , $6.9 million and $7.5 million for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and fiscal 2016, respectively. Generally, it has been the Company's practice and intention to reinvest the earnings of its non-U.S. subsidiaries in those operations. As previously noted, the Tax Act made significant changes to the taxation of undistributed earnings, requiring that all previously untaxed earnings and profits of the Company's controlled foreign operations be subjected to the transition tax. Since these earnings have now been subjected to U.S. federal tax they would only be potentially subject to limited other taxes, including foreign withholding and certain state taxes. As of December 31, 2018, the Company has no t recognized a deferred tax liability for foreign withholdings and state taxes on its undistributed international earnings or losses of its foreign subsidiaries since it intends to indefinitely reinvest the earnings outside the United States. The Company has estimated that the amount of the unrecorded deferred tax liability related to undistributed international earnings is less than $1 million .

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans The Company provides a 401(k) savings plan for eligible U.S. based employees. Employee contributions are discretionary up to the IRS limits each year and catch up contributions are allowed for employees 50 years of age or older. Under the 401(k) plan, employees become eligible to participate on the first day of the month after three months of continuous service. Under this plan, the Company matches 50% of the employee’s contributions up to 6% of the employee’s annual compensation, as defined by the plan. There is a five -year vesting schedule for the Company match. The Company’s contribution to the plan was $3.9 million , $3.7 million , $2.0 million and $3.5 million for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016, respectively. The Company participates with other employers in contributing to the Boilermaker-Blacksmith National Pension Trust (EIN 48-6168020) (“Boilermakers”) and Plumbers and Pipefitters National Pension Fund (EIN 52-6152779) (“Pipefitters”), multi-employer defined benefit pension plans, which covers certain U.S. based union employees. The plans provide multiple plan benefits with corresponding contribution rates that are collectively bargained between participating employers and their affiliated Boilermakers and Pipefitters local unions. Both the Boilermakers and Pipefitters plans are between 65 percent and 80 percent funded as of the latest Form 5500 filed. The Company’s contributions to the Boilermakers and Pipefitters plans, collectively, were $0.6 million , $2.4 million , $1.5 million and $2.5 million for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016. These contributions represented less than five percent of total contributions made to the plans. The Company has other benefit plans covering certain employees throughout the Company. Amounts charged to expense under these plans were not significant in any year.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions On August 17, 2016, the Company entered into an agreement with its then Chairman, CEO and Director, Dr. Sotirios Vahaviolos, to purchase up to 1 million of his shares, commencing in October 2016. Refer to Note 20 for further details of the treasury stock repurchases from Dr. Vahaviolos. The Company leases its headquarters under an operating lease from a shareholder and officer of the Company. On August 1, 2014, the Company extended its lease at its headquarters requiring monthly payments through October 2024. Total rent payments made during the year ended December 31, 2018 were approximately $1.0 million . See Note 18 for further detail related to operating leases. The Company has a lease for office space located in France, which is partly owned by a shareholder and officer. Total rent payments made during the year ended December 31, 2018 were approximately $0.1 million . During 2018, the shareholder and officer sold his interest in this property, and as a result, is no longer a related party as of December 31, 2018. The Company has a lease for office space located in Brazil, which is partly owned by a shareholder and officer. Total rent payments made during the year ended December 31, 2018 were approximately $0.1 million . During 2018, the shareholder and officer sold his interest in this property, and as a result, is no longer a related party as of December 31, 2018. The Company receives benefits consulting services from Capital Management Enterprise (“CME”), which is owned by one of its non-employee directors, Manuel N. Stamatakis. The Company does not pay any fees directly to CME. Any compensation CME receives is from third-party benefit providers.

Obligations under Capital Lease

Obligations under Capital Leases	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Obligations under Capital Leases	Obligations under Capital Leases The Company leases certain office space, and service equipment under capital leases, requiring monthly payments ranging from less than $1 thousand to $63 thousand , including effective interest rates that range from approximately 1% to 11% expiring through June 2029. The net book value of assets under capital lease obligations was $14.6 million and $19.5 million at December 31, 2018 and December 31, 2017, respectively. Scheduled future minimum lease payments subsequent to December 31, 2018 are as follows: 2019 $ 4,686 2020 3,489 2021 2,757 2022 1,475 2023 807 Thereafter 773 Total minimum lease payments 13,987 Less: amount representing interest (990 ) Present value of minimum lease payments 12,997 Less: current portion of obligations under capital leases (3,922 ) Obligations under capital leases, net of current portion $ 9,075

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company is party to various non-cancelable operating lease agreements, primarily for its international and domestic office and lab space. Future minimum lease payments under noncancelable operating leases in each of the five years and thereafter subsequent to December 31, 2018 are as follows: 2019 $ 10,939 2020 8,764 2021 6,327 2022 4,826 2023 4,239 Thereafter 10,667 Total $ 45,762 Total rent expense was $12.3 million , $11.8 million , $6.6 million , $11.2 million for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016, respectively. 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 for 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’s subsidiary in France has been involved in a dispute with a former owner of a business in France purchased by the Company’s French subsidiary. The former owner received a judgment in his favor in the amount of approximately $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 Mistras subsequently obtained ownership of the underlying ultrasonic inspection system. A charge for $1.6 million was recorded in 2017 and payment was made in February 2018. A Company vehicle was involved in an accident in which individuals were injured, property was damaged, and businesses alleged impacted by the accident have claimed economic losses. One lawsuit has been filed by one of the injured individuals in the U.S. District Court for the District of Colorado, McAllister v. Mistras Group, Inc . The Company has insurance for these types of matters and believes its insurance is sufficient to cover all claims resulting from this accident. However, the possibility exists that the insurance ultimately will not be sufficient to satisfy all claims, in which case the Company would be responsible for the amount of claims in excess of insurance coverage. 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 may perform additional investigation of 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 reserves 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 explored options to retain a level of union work that would avoid withdrawal liability to the pension plans, but concluded during the third quarter of 2018 that the Company's subsidiaries probably would not obtain sufficient union work to avoid withdrawal liability. Therefore, the Company determined that it is probable that its subsidiary will incur a withdrawal liability related to these multiemployer pension plans and estimated that the total amount of this potential liability is approximately $5.9 million and recorded a charge for that amount during the year ended December 31, 2018. Severance and labor disputes During the year ended December 31, 2018, the Company recorded approximately $1.2 million 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 has not recorded the expected recovery of indemnification for these labor claims as the amount and timing of collection is uncertain as of December 31, 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 a result, the Company decided that it will not renew several of these leasing services contracts when they expire beginning in 2019. Due to the cap on the length of service allowed under the German Labor Lease Act, employees will have to be transitioned off the customer contracts. It is expected that the German subsidiary then will either terminate these employees, creating a severance obligation to the terminated employees, or transition them to the Company's other customers. As of December 31, 2018, the Company had over 200 employees under current staff leasing contracts, which expire through 2021. As of December 31, 2018, the Company estimated it would be required to pay approximately $1.6 million in severance for these employees not otherwise transitioned, and accordingly recorded an accrual for this amount which is included within Selling, General and Administrative expenses for the year ended December 31, 2018. Acquisition-related contingencies The Company is liable for contingent consideration in connection with certain of its acquisitions. As of December 31, 2018 , total potential acquisition-related contingent consideration ranged from zero to $5.8 million and would be payable upon the achievement of specific performance metrics by certain of the acquired companies over the next 1.5 years of operations. See Note 7 to these consolidated financial statements for further information with respect to the Company’s acquisitions completed during the years ended December 31, 2018 and 2017.

Segment Disclosure

Segment Disclosure	12 Months Ended
	Dec. 31, 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 non-destructive testing, and inspection and engineering services that are used to evaluate the structural integrity and reliability of critical energy, 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. The accounting policies of the reportable segments are the same as those described in Note 1. Segment income from operations is one of the primary performance measures used by the Chief Executive Officer, who is the chief operating decision maker, to assess the performance of each segment and make decisions as to resource allocations. Certain general and administrative costs such as human resources, information technology and training are allocated to the segments. Segment income from operations excludes interest and other financial charges and income taxes. Corporate and other assets are comprised principally of cash, deposits, property, plant and equipment, domestic deferred taxes, deferred charges and other assets. Corporate loss from operations consists of administrative charges related to corporate personnel and other charges that cannot be readily identified for allocation to a particular segment. Selected financial information by segment for the periods shown was as follows (intercompany transactions are eliminated in Corporate and eliminations): For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Revenues Services $ 574,619 $ 543,565 $ 293,218 $ 553,279 International 153,448 144,265 104,013 143,025 Products and Systems 23,426 23,297 14,541 30,293 Corporate and eliminations (9,139 ) (10,157 ) (7,611 ) (7,416 ) $ 742,354 $ 700,970 $ 404,161 $ 719,181 For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Gross profit Services $ 151,974 $ 139,160 $ 75,784 $ 145,262 International 45,464 38,974 34,210 43,613 Products and Systems 10,560 9,798 6,920 14,022 Corporate and eliminations (124 ) (220 ) 90 111 $ 207,874 $ 187,712 $ 117,004 $ 203,008 For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Income from operations Services $ 47,126 $ 46,677 $ 22,411 $ 52,552 International 3,953 3,537 10,597 9,293 Products and Systems 2,368 (16,991 ) (254 ) 2,688 Corporate and eliminations (31,226 ) (29,063 ) (15,221 ) (21,356 ) $ 22,221 $ 4,160 $ 17,533 $ 43,177 For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Depreciation and amortization Services $ 24,079 $ 21,649 $ 12,765 $ 22,725 International 8,846 7,768 5,306 7,774 Products and Systems 1,429 2,180 1,372 2,323 Corporate and eliminations 59 (214 ) (244 ) (348 ) $ 34,413 $ 31,383 $ 19,199 $ 32,474 December 31, 2018 2017 Intangible assets, net Services $ 98,362 $ 46,864 International 11,143 13,899 Products and Systems 1,438 2,261 Corporate and eliminations 452 715 $ 111,395 $ 63,739 December 31, 2018 2017 Total assets Services $ 523,506 $ 377,585 International 146,535 150,779 Products and Systems 12,264 12,733 Corporate and eliminations 11,732 13,344 $ 694,037 $ 554,441 Revenue and long-lived assets by geographic area was as follows: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Revenue United States $ 487,414 $ 466,683 $ 256,926 $ 519,361 Other Americas 98,248 86,870 41,777 67,809 Europe 143,312 132,421 91,847 118,566 Asia-Pacific 13,380 14,996 13,611 13,445 $ 742,354 $ 700,970 $ 404,161 $ 719,181 December 31, 2018 2017 Long-lived assets United States $ 230,140 $ 237,616 Other Americas 177,628 36,011 Europe 76,781 80,693 $ 484,549 $ 354,320

Repurchase of Common Stock

Repurchase of Common Stock	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Repurchase of Common Stock	Repurchase of Common Stock On October 7, 2015, the Company's Board of Directors approved a $50 million stock repurchase plan. As part of this plan, on August 17, 2016, the Company entered into an agreement with its Chairman and 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 agreed to purchase from Dr. Vahaviolos up to $2 million of shares each month, at a 2% discount to the average daily price of the Company's common stock for the preceding month. During the transition period ended December 31, 2016, the Company purchased approximately 274,000 shares from Dr. Vahaviolos at an average price of $21.90 per share and an aggregate cost of $6.0 million as well as 146,000 shares in the open market at an average price of $20.48 per share and an aggregate cost of approximately $3.0 million . During the year ended December 31, 2017, the Company purchased approximately 726,000 shares from Dr. Vahaviolos at an average price of $21.93 per share and an aggregate cost of $15.9 million . 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 . The Company retired all of its repurchased shares during the fourth quarter of 2017 and they are not included in common stock issued and outstanding as of December 31, 2017. As of December 31, 2018, approximately $25.1 million remained available to repurchase shares under the stock repurchase plan.

Twelve Months Ended December 31

Twelve Months Ended December 31, 2016 and Seven Months Ended December 31, 2015 Comparative Data (Unaudited)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Twelve Months Ended December 31, 2016 and Seven Months Ended December 31, 2015 Comparative Data (Unaudited)	Twelve Months Ended December 31, 2016 and Seven Months Ended December 31, 2015 Comparative Data (Unaudited) The condensed consolidated statement of income for the twelve months ended December 31, 2016 and the seven months ended December 31, 2015 is as follows: Twelve Months Ended December 31, 2016 Seven Months Ended December 31, 2015 (unaudited) Revenues $ 684,762 $ 427,913 Cost of revenues 468,929 292,718 Depreciation 21,699 12,005 Gross profit 194,134 123,190 Selling, general and administrative expenses 148,914 81,117 Research and engineering 2,670 1,431 Depreciation and amortization 10,689 6,503 Litigation charges 6,320 — Acquisition-related benefit, net (5 ) (959 ) Income from operations 25,546 35,098 Interest expense, net 3,075 3,672 Income before provision for income taxes 22,471 31,426 Provision for income taxes 8,008 11,627 Net income 14,463 19,799 Less: Net income (loss) attributable to non-controlling interests 54 (15 ) Net income available to Mistras Group, Inc. shareholders $ 14,409 $ 19,814 Net income per share: Basic $ 0.50 $ 0.69 Net income per share: Diluted $ 0.48 $ 0.67 Weighted average shares outstanding: Basic 28,960 28,810 Diluted 30,114 29,676

Selected Quarterly Financial In

Selected Quarterly Financial Information (unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Information (unaudited)	Selected Quarterly Financial Information (unaudited) The following is a summary of the quarterly results of operations for calendar years 2018, 2017 and 2016. Fiscal quarter ended December 31, 2018 September 30, 2018 June 30, 2018 March 31, 2018 Revenues $ 180,762 $ 182,169 $ 191,793 $ 187,630 Gross Profit 52,315 52,332 55,083 48,145 Income from operations 2,502 3,017 8,409 6,399 Net income (loss) attributable to Mistras Group, Inc. $ (1,061 ) $ (1,010 ) $ 6,000 $ 2,919 Earnings (loss) per common share: Basic $ (0.04 ) $ (0.04 ) $ 0.21 $ 0.10 Diluted $ (0.04 ) $ (0.04 ) $ 0.20 $ 0.10 Fiscal quarter ended December 31, 2017 September 30, 2017 June 30, 2017 March 31, 2017 Revenues $ 187,643 $ 179,570 $ 170,439 $ 163,318 Gross Profit 50,319 47,897 46,343 43,153 Income (loss) from operations 6,282 (10,375 ) 5,003 3,250 Net income (loss) attributable to Mistras Group, Inc. $ 884 $ (6,968 ) $ 2,217 $ 1,692 Earnings (loss) per common share: Basic $ 0.03 $ (0.25 ) $ 0.08 $ 0.06 Diluted $ 0.03 $ (0.25 ) $ 0.07 $ 0.06 Fiscal quarter ended December 31, 2016 September 30, 2016 June 30, 2016 March 31, 2016 Revenues $ 170,156 $ 168,811 $ 178,340 $ 167,455 Gross Profit 47,978 50,651 51,535 43,970 Income from operations 2,944 12,116 4,840 5,646 Net income attributable to Mistras Group, Inc. $ 963 $ 7,238 $ 2,761 $ 3,447 Earnings per common share: Basic $ 0.03 $ 0.25 $ 0.10 $ 0.12 Diluted $ 0.03 $ 0.24 $ 0.09 $ 0.11

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and Practices (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying audited 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 consolidated balance sheets. The non-controlling interests in net income, net of tax, is classified separately in the accompanying consolidated statements of income. All significant intercompany accounts and transactions have been eliminated in consolidation. On January 3, 2017, the Company's Board of Directors approved a change in the Company's fiscal year from May 31 to December 31, effective December 31, 2016. In connection with this change, the Company previously filed a Transition Report on Form 10-K to report the results of the seven-month transition period from June 1, 2016 to December 31, 2016. In this Annual Report, the periods presented are the years ended December 31, 2018 and 2017, the seven-month transition period from June 1, 2016 to December 31, 2016 and the year ended May 31, 2016. The Company has also included unaudited data for the year ended December 31, 2016 and for the seven months ended December 31, 2015 (See Note 21). For fiscal 2016, Mistras Group, Inc.’s and its subsidiaries’ fiscal years ended on May 31 except for the subsidiaries in the International segment, which ended on April 30. Accordingly, the Company’s International segment subsidiaries were consolidated on a one -month lag. Therefore, in the quarter and year of acquisition, results of acquired subsidiaries in the International segment were generally included in consolidated results for one less month than the actual number of months from the acquisition date to the end of the reporting period. Effective December 31, 2016, the Company's International segment is no longer consolidated on a one month lag, and such change for the seven month transition period ended December 31, 2016 was not material.
Reclassifications	Reclassifications 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.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with U.S. generally accepted accounting principles (GAAP) requires that the Company make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses and disclosure of contingent assets and liabilities at the date of financial statements. The Company bases its estimates and assumptions on historical experience, known or expected trends and various other assumptions that it believes to be reasonable. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates, which may cause the Company’s future results to be significantly affected.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents.
Accounts Receivable	Accounts Receivable Accounts receivable are stated net of an allowance for doubtful accounts and sales allowances. Outstanding accounts receivable balances are reviewed periodically, and allowances are provided at such time that management believes it is probable that such balances will not be collected within a reasonable period of time, to the extent reasonably estimable. The Company extends credit to its customers based upon credit evaluations in the normal course of business, primarily with 30-day terms. Bad debts are provided for based on historical experience and management’s evaluation of outstanding accounts receivable. Accounts are written off when they are deemed uncollectible under GAAP accounting standards.
Concentrations of Credit Risk	Concentration of Credit Risk No customer accounted for 10% or more of our revenues for the year ended December 31, 2018. One customer accounted for 11% and 12% of our revenues for the year ended December 31, 2017 and the transition period ended December 31, 2016, which primarily were generated from the Services segment. One customer accounted for 10% of our revenues in fiscal 2016 , which primarily were generated from the Services segment. Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and accounts receivable. At times, cash deposits may exceed the limits insured by the Federal Deposit Insurance Corporation. The Company believes it is not exposed to any significant credit risk or risk of nonperformance of financial institutions.
Inventories	Inventories Inventories are stated at the lower of cost, as determined by using the first-in, first-out method, or market. Work in process and finished goods inventory include material, direct labor, variable costs and overhead.
Purchased and Internal-Use Software	Purchased and Internal-Use Software The Company capitalizes certain costs that are incurred to purchase or to create and implement internal-use software, which includes software coding, installation and testing. Capitalized costs are amortized on a straight-line basis over three years , the estimated useful life of the software.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are recorded at cost. Depreciation of property, plant and equipment is computed utilizing the straight-line method over the estimated useful lives of the assets. Amortization of leasehold improvements is computed utilizing the straight-line method over the shorter of the remaining lease term or estimated useful life. Repairs and maintenance costs are expensed as incurred.
Goodwill	Goodwill Goodwill represents the excess purchase price of acquired businesses over the fair values attributed to underlying net tangible assets and identifiable intangible assets. The Company tests goodwill for impairment at a “reporting unit” level (which for the Company is represented by (i) our Services segment, (ii) our Products and Systems segment, and (iii) the European component and (iv) Brazilian component of our International segment). Our annual impairment test is conducted on the first day of our fourth quarter, which is October 1. Goodwill is also tested for impairment whenever an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying amount. During the third quarter of 2017, there was a triggering event in the Products and Systems segment that resulted in a $13.2 million goodwill impairment charge. See Note 8 for further details. If the fair value of a reporting unit is less than its carrying value, this is an indicator that the goodwill assigned to that reporting unit may be impaired. As a result of the Company adopting ASU 2017-04, impairment will be recorded in the amount that fair value is less than carrying value, as the ASU eliminated step two of the goodwill impairment process. The Company considers the income and market approaches to estimating the fair value of our reporting units, which requires significant judgment in evaluation of economic and industry trends, estimated future cash flows, discount rates and other factors.
Impairment of Long-lived Assets	Impairment of Long-lived Assets The Company reviews the recoverability of its long-lived assets (or asset groups) on a periodic basis in order to identify indicators of a possible impairment. The assessment for potential impairment is based primarily on the Company’s ability to recover the carrying value of its long-lived assets from expected future undiscounted cash flows. If the total expected future undiscounted cash flows are less than the carrying amount of the assets, a loss is recognized for the difference between fair value (computed based upon the expected future discounted cash flows) and the carrying value of the assets.
Acquisitions	Acquisitions The Company allocates the purchase price of acquired businesses to their identifiable tangible assets and liabilities as well as identifiable intangible assets, such as customer relationships, technology, non-compete agreements and trade names. Certain estimates and judgments are required in the application of the fair value techniques, including estimates of the respective acquisition's future performance and related cash flows, selection of a discount rate and economic lives, and use of Level 3 measurements as defined in Accounting Standards Update ("ASC") 820 Fair Value Measurements and Disclosure. Deferred taxes are recorded for any differences between the assigned values and tax bases of assets and liabilities.
Research and Engineering	Research and Engineering Research and product development costs are expensed as incurred.
Advertising, Promotions and Marketing	Advertising, Promotions and Marketing The costs for advertising, promotion and marketing programs are expensed as incurred and are included in selling, general and administrative expenses.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and other financial current assets and liabilities approximate fair value based on the short-term nature of the items.
Foreign Currency Translation	Foreign Currency Translation The financial position and results of operations of the Company’s foreign subsidiaries are measured using their functional currencies, which are their local currencies. Assets and liabilities of foreign subsidiaries are translated into the U.S. Dollar at the exchange rates in effect at the balance sheet date. Income and expenses are translated at the average exchange rate during the period. Translation gains and losses are reported as a component of other comprehensive (loss) income for the period and included in accumulated other comprehensive (loss) income within stockholders’ equity. Foreign currency (gains) and losses arising from transactions denominated in currencies other than the functional currency are included in net income, reported in SG&A expenses,
Self-Insurance	Self-Insurance The Company is self-insured for certain losses relating to workers’ compensation and health benefit claims. The Company maintains third-party excess insurance coverage for all workers' compensation and health benefit claims in excess of approximately $0.3 million per occurence to reduce its exposure from such claims. Self-insured losses are accrued when it is probable that an uninsured claim has been incurred but not reported and the amount of the loss can be reasonably estimated at the balance sheet date.
Share-based Compensation	Share-based Compensation The value of services received from employees and directors in exchange for an award of an equity instrument is measured based on the grant-date fair value of the award. Such value is recognized as a non-cash expense on a straight-line basis over the period the individual provides services, which is typically the vesting period of the award with the exception of awards with graded vesting that contain an internal performance measure where each tranche is recognized on a straight-line basis over its vesting period subject to the probability of meeting the performance requirements and adjusted for the number of shares expected to be earned. As share-based compensation expense is based on awards ultimately expected to vest, the amount of expense is reduced for estimated forfeitures. The cost of these awards is recorded in selling, general and administrative expense in the Company’s consolidated statements of income.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and tax credit carry-forwards. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred income tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is provided if it is more likely than not that some or all of a deferred income tax asset will not be realized. Financial accounting standards prescribe a minimum recognition threshold a tax position is required to meet before being recognized in the financial statements. These standards also provide guidance on de-recognition, measurement, and classification of amounts relating to uncertain tax positions, accounting for and disclosure of interest and penalties, accounting in interim periods and disclosures required. Interest and penalties related to unrecognized tax positions are recognized as incurred within “provision for income taxes” in the consolidated statements of income.
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 ASUs 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. The Company's additional required disclosures under Topic 606 are disclosed in Note 2. 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. 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. ASC 842 also requires expanded financial statement disclosures on leasing activities. These changes will become effective for the Company on January 1, 2019. The Company’s cross-functional team has determined the scope of arrangements that will be subject to this standard and continues to evaluate the impact of Topic 842 and its impacts on the Company’s business processes, systems and internal controls. The Company’s lease portfolio primarily includes buildings, machinery and equipment, vehicles and computer equipment. In adopting ASC 842, the new standard provides for several optional practical expedients in transition. The Company will adopt ASC 842 using the following practical expedients: • The optional transition method set forth in ASU 2018-11 in connection with the adoption of ASC 842 on January 1, 2019. • The “package of practical expedients,” which permits the Company not to reassess under the new standard prior conclusions on lease identification, lease classification and initial direct costs. • The practical expedient not to separate lease and non-lease components within the lease and account for all lease components as a single lease component. The Company has estimated the impact of a right-to-use asset and liability on the consolidated balance sheet related to operating leases of between $35 million and $40 million , while the accounting for capital leases will remain unchanged. The adoption of ASC 842 is not expected to result in significant impacts to our statements of income or cash flows. 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 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 their 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 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 periods 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 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 December 31, 2018, the Company has completed the accounting for the tax effects of all of the provisions of the Tax Act.
Revenue	Contract Balances The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits (contract liabilities) on the consolidated balance 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 receives 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 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 $5.3 million . Changes in the contract asset and liability balances during the year ended December 31, 2018, were not impacted by any other factors. The Company has elected to utilize a practical expedient to expense incremental costs incurred related to obtaining a contract. 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 consolidated financial statements, other than the new disclosure requirements below. 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.
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. It also establishes a three level hierarchy that prioritizes the inputs used to measure fair value. The three levels of the hierarchy are defined as follows: Level 1 — Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 — Observable inputs other than quoted prices included in Level 1, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability and inputs derived principally from or corroborated by observable market data. Level 3 — Unobservable inputs reflecting the Company’s own assumptions about inputs that market participants would use in pricing the asset or liability based on the best information available. 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)	12 Months Ended
	Dec. 31, 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: Year ended December 31, 2018 Services International Products Corp/Elim Total Oil & Gas $ 378,904 $ 37,953 $ 1,255 $ — $ 418,112 Aerospace & Defense 50,500 54,853 2,355 — 107,708 Industrials 60,594 26,209 3,097 — 89,900 Power generation & Transmission 30,687 8,522 4,904 — 44,113 Other Process Industries 26,425 9,497 124 — 36,046 Infrastructure, Research & Engineering 11,283 9,032 5,246 — 25,561 Other 16,226 7,382 6,445 (9,139 ) 20,914 Total $ 574,619 $ 153,448 $ 23,426 $ (9,139 ) $ 742,354 Revenue per key geographic location was as follows: Year ended December 31, 2018 Services International Products Corp/Elim Total United States $ 478,853 $ 568 $ 11,493 $ (3,500 ) $ 487,414 Other Americas 90,823 7,995 1,068 (1,638 ) 98,248 Europe 4,252 138,948 3,958 (3,846 ) 143,312 Asia-Pacific 691 5,937 6,907 (155 ) 13,380 Total $ 574,619 $ 153,448 $ 23,426 $ (9,139 ) $ 742,354

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 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: For the year ended December 31, For the transition period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Basic earnings (loss) per share Numerator: Net income (loss) attributable to Mistras Group, Inc. $ 6,836 $ (2,175 ) $ 9,568 $ 24,654 Denominator Weighted average common shares outstanding 28,406 28,422 28,989 28,856 Basic earnings (loss) per share $ 0.24 $ (0.08 ) $ 0.33 $ 0.85 Diluted earnings (loss) per share: Numerator: Net income (loss) attributable to Mistras Group, Inc. $ 6,836 $ (2,175 ) $ 9,568 $ 24,654 Denominator Weighted average common shares outstanding 28,406 28,422 28,989 28,856 Dilutive effect of stock options outstanding 683 — 791 712 Dilutive effect of restricted stock units outstanding 338 — 345 323 29,427 28,422 30,125 29,891 Diluted earnings (loss) per share $ 0.23 $ (0.08 ) $ 0.32 $ 0.82
Schedule of Potential Common Shares Excluded From the Computation of Diluted Earnings Per Share	The following potential common shares were excluded from the computation of diluted earnings per share, as the effect would have been anti-dilutive: For the year ended December 31, For the transition period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Potential common stock attributable to stock options outstanding 5 810 (1 ) — 5 Potential common stock attributable to restricted stock units (RSUs) and performance stock units (PSUs) outstanding 1 353 (2 ) 2 24 Total 6 1,163 2 29 (1) - 805 shares related to stock options were excluded from the calculation of diluted EPS due to the net loss for the period. (2) - 351 shares related to RSUs and PSUs were excluded from the calculation of diluted EPS due to the net loss for the period.

Accounts Receivable, net (Table

Accounts Receivable, net (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of Accounts Receivable, Net	Accounts receivable consist of the following: December 31, December 31, 2018 2017 Trade accounts receivable $ 152,511 $ 141,952 Allowance for doubtful accounts (4,187 ) (3,872 ) Accounts receivable, net $ 148,324 $ 138,080

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consist of the following: December 31, December 31, 2018 2017 Raw materials $ 6,975 $ 5,105 Work in progress 1,019 1,192 Finished goods 2,640 2,746 Consumable supplies 2,419 1,460 Inventory $ 13,053 $ 10,503

Property, Plant and Equipment_2

Property, Plant and Equipment, net (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment, Net	Property, plant and equipment consist of the following: December 31, December 31, Useful Life 2018 2017 (Years) Land $ 2,680 $ 2,414 Building and improvements 30-40 24,338 24,003 Office furniture and equipment 5-8 16,170 14,230 Machinery and equipment 5-7 208,245 191,721 251,433 232,368 Accumulated depreciation and amortization (157,538 ) (145,225 ) Property, plant and equipment, net $ 93,895 $ 87,143

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Estimated Fair Value of Assets Acquired and Liabilities Assumed at the Date of Acquisition	The following table summarizes the estimated fair value of the assets acquired and liabilities assumed, the Company's allocation of purchase price and any subsequent adjustments made during the years ended December 31, 2018 and 2017: Year ended December 31, 2018 Year ended December 31, 2017 Number of entities 1 3 Cash paid $ 143,139 $ 83,963 Working capital adjustments — 150 Notes payable — — Contingent consideration — 3,407 Consideration paid $ 143,139 $ 87,520 Current net assets $ 9,381 $ 7,165 Other assets 136 — Debt and other liabilities (4,976 ) (2,848 ) Property, plant and equipment 8,549 11,115 Deferred tax liability (12,672 ) (1,278 ) Intangibles 59,558 31,671 Goodwill 83,163 41,695 Net assets acquired $ 143,139 $ 87,520
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 (benefit) expense, net, on the consolidated statements of income and were as follows for the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and fiscal 2016: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Due diligence, professional fees and other transaction costs $ 1,248 $ 945 $ 231 $ 629 Adjustments to fair value of contingent consideration liabilities (716 ) (463 ) 265 (2,082 ) Acquisition-related (benefit) expense, net $ 532 $ 482 $ 496 $ (1,453 )
Schedule of Pro Forma Financial Information	The following table provides unaudited pro forma financial information for the years ended December 31, 2018 and 2017 as if the acquisition of Onstream had occurred on January 1, 2017. (Information in thousands, except per share data). For the year ended December 31, 2018 2017 Total revenue $ 770,222 $ 727,821 Net income (loss) 6,602 (2,180 ) Net income (loss) per common share: basic $ 0.23 $ (0.08 ) Net income (loss) per common share: diluted $ 0.22 $ (0.08 )

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Goodwill by Segment	The changes in the carrying amount of goodwill by segment is shown below: Services International Products and Systems Total Balance at December 31, 2016 $ 123,392 $ 33,351 $ 13,197 $ 169,940 Goodwill acquired during the year 41,695 — — 41,695 Impairment charge — — (13,197 ) (13,197 ) Adjustments to preliminary purchase price allocations (211 ) — — (211 ) Foreign currency translation 925 4,286 — 5,211 Balance at December 31, 2017 $ 165,801 $ 37,637 $ — $ 203,438 Goodwill acquired during the year 83,163 — — 83,163 Adjustments to preliminary purchase price allocations (1,977 ) — — (1,977 ) Foreign currency translation (3,511 ) (1,854 ) — (5,365 ) Balance at December 31, 2018 $ 243,476 $ 35,783 $ — $ 279,259

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Gross Amount and Accumulated Amortization of Intangible Assets	The gross carrying amount and accumulated amortization of intangible assets were as follows: December 31, December 31, 2018 2017 Useful Life (Years) Gross Accumulated Net Gross Accumulated Impairment Net Customer relationships 5-14 $ 112,624 $ (60,993 ) $ 51,631 $ 113,299 $ (58,107 ) $ (170 ) $ 55,022 Software/Technology 3-15 67,240 (13,319 ) 53,921 19,523 (14,133 ) (2,411 ) 2,979 Covenants not to compete 2-5 12,593 (10,825 ) 1,768 12,510 (10,438 ) — 2,072 Other 2-12 10,317 (6,242 ) 4,075 10,109 (6,411 ) (32 ) 3,666 Total $ 202,774 $ (91,379 ) $ 111,395 $ 155,441 $ (89,089 ) $ (2,613 ) $ 63,739
Schedule of Expected Amortization Expense of Intangible Assets	Amortization expense in each of the five years and thereafter subsequent to December 31, 2018 related to the Company’s intangible assets is expected to be as follows: Expected Amortization Expense 2019 $ 13,735 2020 12,368 2021 11,292 2022 10,722 2023 9,946 Thereafter 53,332 Total $ 111,395

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following: December 31, 2018 2017 Accrued salaries, wages and related employee benefits $ 29,959 $ 27,185 Contingent consideration 1,687 3,430 Accrued workers' compensation and health benefits 5,086 5,181 Deferred revenues 5,046 6,338 Legal settlement accrual — 1,600 Pension accrual 5,585 — Other accrued expenses 26,532 21,827 Total accrued expenses and other current liabilities $ 73,895 $ 65,561

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt consists of the following: December 31, 2018 2017 Senior credit facility $ 181,656 $ 156,948 Senior secured term loan, net of debt issuance costs of $0.1 million 99,897 — Notes payable 68 228 Other 8,999 9,702 Total debt 290,620 166,878 Less: Current portion (6,833 ) (2,358 ) Long-term debt, net of current portion $ 283,787 $ 164,520
Schedule of Principal Payments Due Under All Borrowing Agreements	Scheduled principal payments due under all borrowing agreements in each of the five years and thereafter subsequent to December 31, 2018 are as follows: 2019 $ 6,831 2020 6,515 2021 8,750 2022 11,030 2023 255,043 Thereafter 2,451 Total $ 290,620

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Changes in Fair Value Level 3 Contingent Consideration	The following table represents the changes in the fair value of Level 3 contingent consideration: Balance at December 31, 2016 $ 3,094 Acquisitions 3,407 Payments (560 ) Accretion of liability 272 Revaluation (735 ) Foreign currency translation 30 Balance at December 31, 2017 $ 5,508 Acquisitions — Payments (2,277 ) Accretion of liability 175 Revaluation (891 ) Foreign currency translation (150 ) Balance at December 31, 2018 $ 2,365

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Cash Proceeds and Aggregate Fair Value of Stock Options Exercised	Cash proceeds from, and the intrinsic value of, stock options exercised during the years ended December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016 were as follows: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Cash proceeds from options exercised $ 273 $ 275 $ 604 $ 543 Aggregate intrinsic value of options exercised 277 580 993 658
Schedule of Stock Options Activity	A summary of the stock option activity, weighted average exercise prices, and options outstanding and exercisable as of December 31, 2018 and 2017, the transition period ended December 31, 2016 and the year ended May 31, 2016 is as follows (in thousands, except per share amounts): For the years ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Common Stock Options Weighted Average Exercise Price Common Weighted Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Outstanding at beginning of year: 2,130 $ 13.43 2,167 $ 13.33 2,232 $ 13.21 2,287 $ 13.13 Granted — $ — — $ — — $ — — $ — Exercised (25 ) $ 10.75 (37 ) $ 7.39 (65 ) $ 9.27 (55 ) $ 9.87 Expired or forfeited — $ — — $ — — $ — — $ — Outstanding at end of year: 2,105 $ 13.47 2,130 $ 13.43 2,167 $ 13.33 2,232 $ 13.21
Schedule of Stock Options Outstanding and Exercisable	For the year ended December 31, 2018 Options Outstanding Options Exercisable Range of Exercise Prices Total Options Outstanding Weighted Average Remaining Life (Years) Weighted Average Exercise Price Number Exercisable Weighted Average Exercise Price $10.00-$10.00 10 0.3 $ 10.00 10 $ 10.00 $13.46-$22.35 2,095 0.7 $ 13.48 2,095 $ 13.48 2,105 2,105 Aggregate Intrinsic Value $ 1,965 $ 1,965
Schedule of Vesting Activity of Restricted Stock Units	A summary of the vesting activity of restricted stock unit awards, with the respective fair value of the awards, is as follows: (awards in thousands, fair value in millions): For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Restricted stock awards vested 258 185 207 223 Fair value of awards vested $ 5.3 $ 3.4 $ 5.1 $ 3.5
Schedule of Fully-vested Common Stocks Issued to Non-employee Directors	A summary of the fully-vested common stock the Company issued to its five non-employee directors, in connection with its non-employee director compensation plan, is as follows: (awards in thousands, fair value in millions) For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Awards issued 19 21 10 28 Grant date fair value of awards issued $ 0.4 $ 0.4 $ 0.3 $ 0.5
Schedule of Non-vested Restricted Share Units	A summary of the Company's outstanding, non-vested restricted share units is presented below: For the year ended December 31, For the transition period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Units Weighted Units Weighted Units Weighted Units Weighted Average Grant-Date Fair Value Outstanding at beginning of period: 532 $ 21.05 569 $ 20.81 575 $ 18.85 564 $ 20.47 Granted 211 $ 19.20 183 $ 21.26 219 $ 24.48 264 $ 16.73 Released (258 ) $ 20.48 (185 ) $ 20.49 (207 ) $ 19.40 (223 ) $ 20.40 Forfeited (42 ) $ 20.52 (35 ) $ 21.45 (18 ) $ 19.55 (30 ) $ 19.26 Outstanding at end of period: 443 $ 20.55 532 $ 21.05 569 $ 20.81 575 $ 18.85
Schedule of Performance Shares Units Activity	A summary of the Company's PRSU activity is presented below: For the year ended December 31, For the transition period ended December 31, 2018 2017 2016 Units Weighted Units Weighted Units Weighted Outstanding at beginning of period: 278 $ 17.00 290 $ 16.01 328 $ 17.02 Granted 129 $ 19.46 128 $ 20.42 105 $ 24.90 Performance condition adjustments, net (50 ) $ 19.48 (68 ) $ 20.55 (54 ) $ 24.49 Released (68 ) $ 16.03 (72 ) $ 15.82 (89 ) $ 24.50 Forfeited (12 ) $ 16.16 — $ — — $ — Outstanding at end of period: 277 $ 17.80 278 $ 17.00 290 $ 16.01

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Income Before Provision for Income Taxes	Income before provision for income taxes is as follows: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Income (loss) before provision for income taxes from: U.S. operations $ 9,853 $ (7,303 ) $ 5,116 $ 27,772 Foreign operations 4,418 7,077 10,365 10,643 Earnings (loss) before income taxes $ 14,271 $ (226 ) $ 15,481 $ 38,415
Schedule of Provision for Income Taxes	The provision for income taxes consists of the following: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Current Federal $ 790 $ 3,558 $ 1,990 $ 9,156 States and local 533 39 483 1,537 Foreign 3,824 3,131 3,569 3,672 Reserve for uncertain tax positions 337 71 (39 ) (529 ) Total current 5,484 6,799 6,003 13,836 Deferred Federal 2,966 (3,857 ) 6 82 States and local 399 (810 ) (28 ) (51 ) Foreign (2,089 ) (437 ) (514 ) (557 ) Total deferred 1,276 (5,104 ) (536 ) (526 ) Net change in valuation allowance 666 247 403 455 Net deferred 1,942 (4,857 ) (133 ) (71 ) Provision for income taxes $ 7,426 $ 1,942 $ 5,870 $ 13,765
Schedule of Provision for Income Taxes Computed by Applying Statutory Federal Tax Rate	For the year ended May 31, 2016 Federal tax at statutory rate $ 13,445 35.0 % State taxes, net of federal benefit 966 2.5 % Foreign tax (610 ) (1.6 )% Contingent consideration (425 ) (1.1 )% Permanent differences 245 0.6 % Other (311 ) (0.8 )% Change in valuation allowance 455 1.2 % Total provision for income taxes $ 13,765 35.8 % The provision for income taxes differs from the amount computed by applying the statutory federal tax rate to income tax as follows: For the years ended December 31, For the Transition period ended December 31, 2018 2017 2016 Federal tax at statutory rate $ 2,997 21.0 % $ (79 ) 35.0 % $ 5,418 35.0 % State taxes, net of federal benefit 737 5.1 % (502 ) 221.6 % 296 1.9 % Foreign tax 807 5.7 % 217 (95.8 )% (573 ) (3.7 )% Contingent consideration (6 ) — % (63 ) 27.7 % (4 ) — % Nondeductible compensation 183 1.3 % — — % — — % US taxation of foreign earnings 228 1.6 % — — % — — % Permanent differences 361 2.5 % 377 (166.4 )% 373 2.4 % Transition tax, net of foreign tax credits 1,158 8.1 % 3,942 (1,741.4 )% — — % Federal tax rate change due to the Tax Act 87 0.6 % (1,956 ) 864.0 % — — % Other 208 1.4 % (241 ) 106.5 % (43 ) (0.3 )% Change in valuation allowance 666 4.7 % 247 (109.1 )% 403 2.6 % Total provision for income taxes $ 7,426 52.0 % $ 1,942 (857.9 )% $ 5,870 37.9 %
Schedule of Deferred Income Tax Assets and Liabilities	Deferred income tax attributes resulting from differences between financial accounting amounts and income tax basis of assets and liabilities are as follows: December 31, 2018 2017 Deferred income tax assets Allowance for doubtful accounts $ 951 $ 838 Inventory 285 265 Intangible assets 1,230 2,255 Accrued expenses 4,408 2,560 Net operating loss carryforward 3,889 3,729 Capital lease obligations 731 1,004 Capital losses 462 463 Foreign tax credit carryover — 618 Deferred share-based compensation 3,728 4,080 Other 699 484 Deferred income tax assets 16,383 16,296 Valuation allowance (4,235 ) (4,044 ) Net deferred income tax assets 12,148 12,252 Deferred income tax liabilities Property and equipment (7,597 ) (6,893 ) Goodwill (9,302 ) (6,578 ) Intangible assets (16,459 ) (5,972 ) Other (8 ) (6 ) Deferred income tax liabilities (33,366 ) (19,449 ) Net deferred income taxes $ (21,218 ) $ (7,197 )
Schedule of Changes in Company's Gross Unrecognized Tax Benefits, Excluding Interest and Penalties	The following table summarizes the changes in the Company’s gross unrecognized tax benefits, excluding interest and penalties: For the year ended December 31, 2018 2017 Balance at beginning of period $ 156 $ 267 Additions for tax positions related to the current fiscal period 1 11 Additions for tax positions related to prior years 341 188 Decreases for tax positions related to prior years (2 ) — Current year acquisitions 270 — Impact of foreign exchange fluctuation — 10 Settlements (4 ) (198 ) Reductions related to the expiration of statutes of limitations (39 ) (122 ) Balance at end of period $ 723 $ 156

Obligations under Capital Lea_2

Obligations under Capital Leases (Tables)	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Scheduled Future Minimum Capital Lease Payments	Scheduled future minimum lease payments subsequent to December 31, 2018 are as follows: 2019 $ 4,686 2020 3,489 2021 2,757 2022 1,475 2023 807 Thereafter 773 Total minimum lease payments 13,987 Less: amount representing interest (990 ) Present value of minimum lease payments 12,997 Less: current portion of obligations under capital leases (3,922 ) Obligations under capital leases, net of current portion $ 9,075

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments Under Noncancelable Operating Leases	Future minimum lease payments under noncancelable operating leases in each of the five years and thereafter subsequent to December 31, 2018 are as follows: 2019 $ 10,939 2020 8,764 2021 6,327 2022 4,826 2023 4,239 Thereafter 10,667 Total $ 45,762

Segment Disclosure (Tables)

Segment Disclosure (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Financial Information by Segment	Selected financial information by segment for the periods shown was as follows (intercompany transactions are eliminated in Corporate and eliminations): For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Revenues Services $ 574,619 $ 543,565 $ 293,218 $ 553,279 International 153,448 144,265 104,013 143,025 Products and Systems 23,426 23,297 14,541 30,293 Corporate and eliminations (9,139 ) (10,157 ) (7,611 ) (7,416 ) $ 742,354 $ 700,970 $ 404,161 $ 719,181 For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Gross profit Services $ 151,974 $ 139,160 $ 75,784 $ 145,262 International 45,464 38,974 34,210 43,613 Products and Systems 10,560 9,798 6,920 14,022 Corporate and eliminations (124 ) (220 ) 90 111 $ 207,874 $ 187,712 $ 117,004 $ 203,008 For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Income from operations Services $ 47,126 $ 46,677 $ 22,411 $ 52,552 International 3,953 3,537 10,597 9,293 Products and Systems 2,368 (16,991 ) (254 ) 2,688 Corporate and eliminations (31,226 ) (29,063 ) (15,221 ) (21,356 ) $ 22,221 $ 4,160 $ 17,533 $ 43,177 For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Depreciation and amortization Services $ 24,079 $ 21,649 $ 12,765 $ 22,725 International 8,846 7,768 5,306 7,774 Products and Systems 1,429 2,180 1,372 2,323 Corporate and eliminations 59 (214 ) (244 ) (348 ) $ 34,413 $ 31,383 $ 19,199 $ 32,474 December 31, 2018 2017 Intangible assets, net Services $ 98,362 $ 46,864 International 11,143 13,899 Products and Systems 1,438 2,261 Corporate and eliminations 452 715 $ 111,395 $ 63,739 December 31, 2018 2017 Total assets Services $ 523,506 $ 377,585 International 146,535 150,779 Products and Systems 12,264 12,733 Corporate and eliminations 11,732 13,344 $ 694,037 $ 554,441
Schedule of Revenue and Long-lived Assets by Geographic Area	Revenue and long-lived assets by geographic area was as follows: For the year ended December 31, For the Transition Period ended December 31, For the year ended May 31, 2018 2017 2016 2016 Revenue United States $ 487,414 $ 466,683 $ 256,926 $ 519,361 Other Americas 98,248 86,870 41,777 67,809 Europe 143,312 132,421 91,847 118,566 Asia-Pacific 13,380 14,996 13,611 13,445 $ 742,354 $ 700,970 $ 404,161 $ 719,181 December 31, 2018 2017 Long-lived assets United States $ 230,140 $ 237,616 Other Americas 177,628 36,011 Europe 76,781 80,693 $ 484,549 $ 354,320

Twelve Months Ended December _2

Twelve Months Ended December 31, 2016 and Seven Months Ended December 31, 2015 Comparative Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Consolidated of Income for the Twelve Months Ended December 31, 2016 and Seven Months ended December 31, 2015	The condensed consolidated statement of income for the twelve months ended December 31, 2016 and the seven months ended December 31, 2015 is as follows: Twelve Months Ended December 31, 2016 Seven Months Ended December 31, 2015 (unaudited) Revenues $ 684,762 $ 427,913 Cost of revenues 468,929 292,718 Depreciation 21,699 12,005 Gross profit 194,134 123,190 Selling, general and administrative expenses 148,914 81,117 Research and engineering 2,670 1,431 Depreciation and amortization 10,689 6,503 Litigation charges 6,320 — Acquisition-related benefit, net (5 ) (959 ) Income from operations 25,546 35,098 Interest expense, net 3,075 3,672 Income before provision for income taxes 22,471 31,426 Provision for income taxes 8,008 11,627 Net income 14,463 19,799 Less: Net income (loss) attributable to non-controlling interests 54 (15 ) Net income available to Mistras Group, Inc. shareholders $ 14,409 $ 19,814 Net income per share: Basic $ 0.50 $ 0.69 Net income per share: Diluted $ 0.48 $ 0.67 Weighted average shares outstanding: Basic 28,960 28,810 Diluted 30,114 29,676

Selected Quarterly Financial _2

Selected Quarterly Financial Information (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Results of Operations	The following is a summary of the quarterly results of operations for calendar years 2018, 2017 and 2016. Fiscal quarter ended December 31, 2018 September 30, 2018 June 30, 2018 March 31, 2018 Revenues $ 180,762 $ 182,169 $ 191,793 $ 187,630 Gross Profit 52,315 52,332 55,083 48,145 Income from operations 2,502 3,017 8,409 6,399 Net income (loss) attributable to Mistras Group, Inc. $ (1,061 ) $ (1,010 ) $ 6,000 $ 2,919 Earnings (loss) per common share: Basic $ (0.04 ) $ (0.04 ) $ 0.21 $ 0.10 Diluted $ (0.04 ) $ (0.04 ) $ 0.20 $ 0.10 Fiscal quarter ended December 31, 2017 September 30, 2017 June 30, 2017 March 31, 2017 Revenues $ 187,643 $ 179,570 $ 170,439 $ 163,318 Gross Profit 50,319 47,897 46,343 43,153 Income (loss) from operations 6,282 (10,375 ) 5,003 3,250 Net income (loss) attributable to Mistras Group, Inc. $ 884 $ (6,968 ) $ 2,217 $ 1,692 Earnings (loss) per common share: Basic $ 0.03 $ (0.25 ) $ 0.08 $ 0.06 Diluted $ 0.03 $ (0.25 ) $ 0.07 $ 0.06 Fiscal quarter ended December 31, 2016 September 30, 2016 June 30, 2016 March 31, 2016 Revenues $ 170,156 $ 168,811 $ 178,340 $ 167,455 Gross Profit 47,978 50,651 51,535 43,970 Income from operations 2,944 12,116 4,840 5,646 Net income attributable to Mistras Group, Inc. $ 963 $ 7,238 $ 2,761 $ 3,447 Earnings per common share: Basic $ 0.03 $ 0.25 $ 0.10 $ 0.12 Diluted $ 0.03 $ 0.24 $ 0.09 $ 0.11

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and Practices (Details)	Oct. 01, 2018USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2016USD ($)mo	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	May 31, 2016	Dec. 31, 2016USD ($)	Jan. 01, 2019USD ($)
Concentration Risk [Line Items]
Goodwill impairment charge	$ 0					$ 13,197,000
Foreign currency (gains) and losses					$ 1,300,000	600,000
Minimum amount of excess self-insurance claims paid to reduce exposure					300,000
Subsequent Event | Scenario, Forecast | ASC 842 | Minimum
Concentration Risk [Line Items]
Operating lease, right-to-use asset									$ 35,000,000
Operating lease liability									35,000,000
Subsequent Event | Scenario, Forecast | ASC 842 | Maximum
Concentration Risk [Line Items]
Operating lease, right-to-use asset									40,000,000
Operating lease liability									$ 40,000,000
Selling, General and Administrative Expenses
Concentration Risk [Line Items]
Advertising expense				$ 1,200,000	$ 2,100,000	1,900,000		$ 1,800,000
Foreign currency (gains) and losses				$ (700,000)				$ (100,000)
Software/Technology
Concentration Risk [Line Items]
Estimated useful life of software					3 years
Software/Technology | Minimum
Concentration Risk [Line Items]
Estimated useful life of software					3 years
Software/Technology | Maximum
Concentration Risk [Line Items]
Estimated useful life of software					15 years
International
Concentration Risk [Line Items]
Difference of period between the consolidation of International segment subsidiaries				1 month
Number of months less than the actual number of months from the acquisition date for which results of international segment subsidiaries are included in consolidation | mo				1
Goodwill impairment charge						0
Products and Systems
Concentration Risk [Line Items]
Goodwill impairment charge		$ 13,200,000				13,197,000
Products and Systems | Software/Technology
Concentration Risk [Line Items]
Impairment charge of long-lived assets			$ 2,600,000			$ 2,400,000
Customer One | Customer concentration risk | Revenues
Concentration Risk [Line Items]
Percentage of concentration risk				12.00%		11.00%	10.00%

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 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	$ 5.3

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	7 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 404,161	$ 427,913	$ 742,354	$ 700,970	$ 684,762	$ 719,181
United States
Disaggregation of Revenue [Line Items]
Revenue	256,926		487,414	466,683		519,361
Other Americas
Disaggregation of Revenue [Line Items]
Revenue	41,777		98,248	86,870		67,809
Europe
Disaggregation of Revenue [Line Items]
Revenue	91,847		143,312	132,421		118,566
Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue	13,611		13,380	14,996		13,445
Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue			418,112
Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue			107,708
Industrials
Disaggregation of Revenue [Line Items]
Revenue			89,900
Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenue			44,113
Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue			36,046
Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue			25,561
Other
Disaggregation of Revenue [Line Items]
Revenue			20,914
Operating segments | Services
Disaggregation of Revenue [Line Items]
Revenue	293,218		574,619	543,565		553,279
Operating segments | Services | United States
Disaggregation of Revenue [Line Items]
Revenue			478,853
Operating segments | Services | Other Americas
Disaggregation of Revenue [Line Items]
Revenue			90,823
Operating segments | Services | Europe
Disaggregation of Revenue [Line Items]
Revenue			4,252
Operating segments | Services | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue			691
Operating segments | Services | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue			378,904
Operating segments | Services | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue			50,500
Operating segments | Services | Industrials
Disaggregation of Revenue [Line Items]
Revenue			60,594
Operating segments | Services | Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenue			30,687
Operating segments | Services | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue			26,425
Operating segments | Services | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue			11,283
Operating segments | Services | Other
Disaggregation of Revenue [Line Items]
Revenue			16,226
Operating segments | International
Disaggregation of Revenue [Line Items]
Revenue	104,013		153,448	144,265		143,025
Operating segments | International | United States
Disaggregation of Revenue [Line Items]
Revenue			568
Operating segments | International | Other Americas
Disaggregation of Revenue [Line Items]
Revenue			7,995
Operating segments | International | Europe
Disaggregation of Revenue [Line Items]
Revenue			138,948
Operating segments | International | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue			5,937
Operating segments | International | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue			37,953
Operating segments | International | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue			54,853
Operating segments | International | Industrials
Disaggregation of Revenue [Line Items]
Revenue			26,209
Operating segments | International | Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenue			8,522
Operating segments | International | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue			9,497
Operating segments | International | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue			9,032
Operating segments | International | Other
Disaggregation of Revenue [Line Items]
Revenue			7,382
Operating segments | Products
Disaggregation of Revenue [Line Items]
Revenue	14,541		23,426	23,297		30,293
Operating segments | Products | United States
Disaggregation of Revenue [Line Items]
Revenue			11,493
Operating segments | Products | Other Americas
Disaggregation of Revenue [Line Items]
Revenue			1,068
Operating segments | Products | Europe
Disaggregation of Revenue [Line Items]
Revenue			3,958
Operating segments | Products | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue			6,907
Operating segments | Products | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue			1,255
Operating segments | Products | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue			2,355
Operating segments | Products | Industrials
Disaggregation of Revenue [Line Items]
Revenue			3,097
Operating segments | Products | Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenue			4,904
Operating segments | Products | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue			124
Operating segments | Products | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue			5,246
Operating segments | Products | Other
Disaggregation of Revenue [Line Items]
Revenue			6,445
Corp/Elim
Disaggregation of Revenue [Line Items]
Revenue	$ (7,611)		(9,139)	$ (10,157)		$ (7,416)
Corp/Elim | United States
Disaggregation of Revenue [Line Items]
Revenue			(3,500)
Corp/Elim | Other Americas
Disaggregation of Revenue [Line Items]
Revenue			(1,638)
Corp/Elim | Europe
Disaggregation of Revenue [Line Items]
Revenue			(3,846)
Corp/Elim | Asia-Pacific
Disaggregation of Revenue [Line Items]
Revenue			(155)
Corp/Elim | Oil & Gas
Disaggregation of Revenue [Line Items]
Revenue			0
Corp/Elim | Aerospace & Defense
Disaggregation of Revenue [Line Items]
Revenue			0
Corp/Elim | Industrials
Disaggregation of Revenue [Line Items]
Revenue			0
Corp/Elim | Power generation & Transmission
Disaggregation of Revenue [Line Items]
Revenue			0
Corp/Elim | Other Process Industries
Disaggregation of Revenue [Line Items]
Revenue			0
Corp/Elim | Infrastructure, Research & Engineering
Disaggregation of Revenue [Line Items]
Revenue			0
Corp/Elim | Other
Disaggregation of Revenue [Line Items]
Revenue			$ (9,139)

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended												7 Months Ended		12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Basic earnings (loss) per share
Net income (loss) attributable to Mistras Group, Inc.	$ (1,061)	$ (1,010)	$ 6,000	$ 2,919	$ 884	$ (6,968)	$ 2,217	$ 1,692	$ 963	$ 7,238	$ 2,761	$ 3,447	$ 9,568	$ 19,814	$ 6,836	$ (2,175)	$ 14,409	$ 24,654
Denominator
Weighted average common shares outstanding (in shares)													28,989	28,810	28,406	28,422	28,960	28,856
Basic (loss) earnings per share (in dollars per share)	$ (0.04)	$ (0.04)	$ 0.21	$ 0.10	$ 0.03	$ (0.25)	$ 0.08	$ 0.06	$ 0.03	$ 0.25	$ 0.10	$ 0.12	$ 0.33	$ 0.69	$ 0.24	$ (0.08)	$ 0.50	$ 0.85
Denominator
Weighted average common shares outstanding (in shares)													28,989	28,810	28,406	28,422	28,960	28,856
Dilutive effect of stock options outstanding (in shares)													791		683	0		712
Dilutive effect of restricted stock units outstanding (in shares)													345		338	0		323
Weighted average common shares outstanding, diluted (in shares)													30,125	29,676	29,427	28,422	30,114	29,891
Diluted (loss) earnings per share (in dollars per share)	$ (0.04)	$ (0.04)	$ 0.20	$ 0.10	$ 0.03	$ (0.25)	$ 0.07	$ 0.06	$ 0.03	$ 0.24	$ 0.09	$ 0.11	$ 0.32	$ 0.67	$ 0.23	$ (0.08)	$ 0.48	$ 0.82

Earnings per Share - Potential

Earnings per Share - Potential Common Shares Excluded From Computation of Diluted Earnings (Details) - shares shares in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock excluded from computation of earnings per share (in shares)	2	6	1,163	29
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock excluded from computation of earnings per share (in shares)	0	5	810	5
Potential common stock excluded from computation of diluted earnings per share due to net loss for the period (in shares)			805
RSUs and PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock excluded from computation of earnings per share (in shares)	2	1	353	24
Potential common stock excluded from computation of diluted earnings per share due to net loss for the period (in shares)			351

Accounts Receivable, net (Detai

Accounts Receivable, net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade accounts receivable	$ 152,511	$ 141,952
Allowance for doubtful accounts	(4,187)	(3,872)
Accounts receivable, net	$ 148,324	$ 138,080

Accounts Receivable, net - Narr

Accounts Receivable, net - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Unbilled revenues	$ 16.1	$ 14.4
Customer One | North America | Services | Customer concentration risk | Accounts Receivable
Concentration Risk [Line Items]
Trade accounts receivable past due from one customer	$ 5.6
Percentage of allowance for doubtful accounts allocated to one past due customer	12.00%

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 6,975	$ 5,105
Work in progress	1,019	1,192
Finished goods	2,640	2,746
Consumable supplies	2,419	1,460
Inventory	$ 13,053	$ 10,503

Property, Plant and Equipment_3

Property, Plant and Equipment, net (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Property, Plant and Equipment, net
Property, plant and equipment, gross		$ 251,433	$ 232,368
Accumulated depreciation and amortization		(157,538)	(145,225)
Property, plant and equipment, net		93,895	87,143
Depreciation expense	$ 14,000	24,200	22,400	$ 22,900
Land
Property, Plant and Equipment, net
Property, plant and equipment, gross		2,680	2,414
Building and improvements
Property, Plant and Equipment, net
Property, plant and equipment, gross		$ 24,338	24,003
Building and improvements | Minimum
Property, Plant and Equipment, net
Useful Life		30 years
Building and improvements | Maximum
Property, Plant and Equipment, net
Useful Life		40 years
Office furniture and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross		$ 16,170	14,230
Office furniture and equipment | Minimum
Property, Plant and Equipment, net
Useful Life		5 years
Office furniture and equipment | Maximum
Property, Plant and Equipment, net
Useful Life		8 years
Machinery and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross		$ 208,245	$ 191,721
Machinery and equipment | Minimum
Property, Plant and Equipment, net
Useful Life		5 years
Machinery and equipment | Maximum
Property, Plant and Equipment, net
Useful Life		7 years

Acquisitions and Dispositions -

Acquisitions and Dispositions - Acquisitions Narrative (Details)	12 Months Ended
	Dec. 31, 2018USD ($)entity	Dec. 31, 2017USD ($)entity	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Goodwill	$ 279,259,000	$ 203,438,000	$ 169,940,000
Revenue for the period subsequent to closing of the transaction	300,000
Aggregate income from operation for the period subsequent to closing of transaction	2,000,000
Acquisition-related expense	$ 1,300,000
Acquisitions in Fiscal 2018
Business Acquisition [Line Items]
Number of complete acquisitions | entity	1
Consideration paid	$ 143,139,000
Cash consideration paid	143,139,000
Contingent consideration liability	0
Working capital adjustments	0
Notes payable assumed	0
Goodwill	83,163,000
Goodwill deductible for tax purposes	0
Finite-lived intangible assets acquired	$ 59,558,000
Acquisitions in Fiscal 2017
Business Acquisition [Line Items]
Number of complete acquisitions | entity		3
Consideration paid		$ 87,520,000
Cash consideration paid		83,963,000
Contingent consideration liability		3,407,000
Working capital adjustments		150,000
Notes payable assumed		0
Goodwill		41,695,000
Finite-lived intangible assets acquired		$ 31,671,000
Minimum
Business Acquisition [Line Items]
Amortization period of intangible assets acquired	2 years
Maximum
Business Acquisition [Line Items]
Amortization period of intangible assets acquired	14 years
Customer Relationships and Noncompete Agreements
Business Acquisition [Line Items]
Finite-lived intangible assets acquired	$ 59,600,000
Canada and U.S.
Business Acquisition [Line Items]
Number of complete acquisitions | entity	1	3
Percentage of equity interest acquired	100.00%	100.00%
Cash consideration paid	$ 143,100,000	$ 79,500,000
Contingent consideration liability		$ 2,400,000
Contingent consideration initial payment period		3 years
Working capital adjustments		$ 200,000
Canada
Business Acquisition [Line Items]
Number of complete acquisitions | entity		1
United States
Business Acquisition [Line Items]
Number of complete acquisitions | entity		1
Cash consideration paid		$ 4,500,000
Contingent consideration liability		$ 3,500,000
Contingent consideration initial payment period		3 years

Acquisitions and Dispositions_2

Acquisitions and Dispositions - Estimated Fair Value of the Assets Acquired and Liabilities Assumed (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)entity	Dec. 31, 2017USD ($)entity	Dec. 31, 2016USD ($)
Estimated fair value of the assets acquired and liabilities assumed
Goodwill	$ 279,259	$ 203,438	$ 169,940
Acquisitions in Fiscal 2018
Business Acquisition [Line Items]
Number of entities | entity	1
Consideration transferred:
Cash paid	$ 143,139
Working capital adjustments	0
Notes payable	0
Contingent consideration	0
Consideration paid	143,139
Estimated fair value of the assets acquired and liabilities assumed
Current net assets	9,381
Other assets	136
Debt and other liabilities	(4,976)
Property, plant and equipment	8,549
Deferred tax liability	(12,672)
Intangibles	59,558
Goodwill	83,163
Net assets acquired	$ 143,139
Acquisitions in Fiscal 2017
Business Acquisition [Line Items]
Number of entities | entity		3
Consideration transferred:
Cash paid		$ 83,963
Working capital adjustments		150
Notes payable		0
Contingent consideration		3,407
Consideration paid		87,520
Estimated fair value of the assets acquired and liabilities assumed
Current net assets		7,165
Other assets		0
Debt and other liabilities		(2,848)
Property, plant and equipment		11,115
Deferred tax liability		(1,278)
Intangibles		31,671
Goodwill		41,695
Net assets acquired		$ 87,520

Acquisitions and Dispositions_3

Acquisitions and Dispositions - Dispositions Narrative (Details) $ in Thousands	3 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2017subsidiary	Dec. 31, 2016USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	May 31, 2016USD ($)	Sep. 30, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of subsidiary		$ 0	$ 2,384	$ 0	$ 0
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Disposal of Foreign Subsidiaries | Products and Systems
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
Impairment charges on subsidiaries held-for-sale				$ 2,600
Percentage of consolidated revenues of subsidiary held-for-sale				0.60%
Loss from operations of subsidiary held-for-sale				$ 3,500
Percentage of consolidated assets of subsidiary held-for-sale	0.40%			0.40%
Percentage consolidated liabilities of subsidiary held-for-sale	0.20%			0.20%
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Disposal of Foreign Subsidiaries | Products and Systems
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received on sale of subsidiary						$ 4,300
Post-closing adjustment included in consideration received from sale of subsidiary						$ 500
Gain on sale of subsidiary			$ 2,400
Term of agreement to purchase products from buyer on sale of subsidiary			3 years
Amount of purchase agreement with buyer on sale of subsidiary			$ 2,300
Remaining amount of purchase agreement with buyer on sale of subsidiary			$ 2,100

Acquisitions and Dispositions_4

Acquisitions and Dispositions - Acquisition-Related Expense (Details) - USD ($) $ in Thousands	7 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Business Acquisition [Line Items]
Adjustments to fair value of contingent consideration liabilities	$ 262		$ (716)	$ (463)		$ (2,066)
Acquisition-related (benefit) expense, net	496	$ (959)	532	482	$ (5)	(1,453)
Acquisitions in Fiscal 2018
Business Acquisition [Line Items]
Due diligence, professional fees and other transaction costs			1,248
Adjustments to fair value of contingent consideration liabilities			(716)
Acquisition-related (benefit) expense, net			$ 532
Acquisitions in Fiscal 2017
Business Acquisition [Line Items]
Due diligence, professional fees and other transaction costs				945
Adjustments to fair value of contingent consideration liabilities				(463)
Acquisition-related (benefit) expense, net				$ 482
Acquisitions in Transition Period Ended December 31, 2016
Business Acquisition [Line Items]
Due diligence, professional fees and other transaction costs	231
Adjustments to fair value of contingent consideration liabilities	265
Acquisition-related (benefit) expense, net	$ 496
Acquisitions in Fiscal 2016
Business Acquisition [Line Items]
Due diligence, professional fees and other transaction costs						629
Adjustments to fair value of contingent consideration liabilities						(2,082)
Acquisition-related (benefit) expense, net						$ (1,453)

Acquisitions and Dispositions_5

Acquisitions and Dispositions - Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Pro Forma Adjustments
Effective tax rate	37.90%	52.00%	(857.90%)	35.80%
Onstream
Business Acquisition [Line Items]
Total revenue		$ 770,222	$ 727,821
Net income (loss)		$ 6,602	$ (2,180)
Net income (loss) per common share: basic (in dollars per share)		$ 0.23	$ (0.08)
Net income (loss) per common share: diluted (in dollars per share)		$ 0.22	$ (0.08)
Pro Forma Adjustments
Effective tax rate		26.00%	31.00%
Onstream | Additional depreciation and amortization expense
Pro Forma Adjustments
Weighted average useful live of intangible assets acquired		12 years 7 months 6 days
Useful life of property, plant and equipment acquired		5 years

Goodwill (Details)

Goodwill (Details) - USD ($)	Oct. 01, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Changes in the carrying amount of goodwill
Balance at the beginning of the period			$ 203,438,000	$ 169,940,000
Goodwill acquired during the year			83,163,000	41,695,000
Impairment charge	$ 0			(13,197,000)
Adjustments to preliminary purchase price allocations			(1,977,000)	(211,000)
Foreign currency translation			(5,365,000)	5,211,000
Balance at the end of the period			279,259,000	203,438,000
Services
Changes in the carrying amount of goodwill
Balance at the beginning of the period			165,801,000	123,392,000
Goodwill acquired during the year			83,163,000	41,695,000
Impairment charge				0
Adjustments to preliminary purchase price allocations			(1,977,000)	(211,000)
Foreign currency translation			(3,511,000)	925,000
Balance at the end of the period			243,476,000	165,801,000
International
Changes in the carrying amount of goodwill
Balance at the beginning of the period			37,637,000	33,351,000
Goodwill acquired during the year			0	0
Impairment charge				0
Adjustments to preliminary purchase price allocations			0	0
Foreign currency translation			(1,854,000)	4,286,000
Balance at the end of the period			35,783,000	37,637,000
Products and Systems
Changes in the carrying amount of goodwill
Balance at the beginning of the period			0	13,197,000
Goodwill acquired during the year			0	0
Impairment charge		$ (13,200,000)		(13,197,000)
Adjustments to preliminary purchase price allocations			0	0
Foreign currency translation			0	0
Balance at the end of the period			$ 0	$ 0

Goodwill - Narrative (Details)

Goodwill - Narrative (Details) - USD ($)	Oct. 01, 2018	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2018
Goodwill
Goodwill impairment charge	$ 0		$ 13,197,000
Goodwill, cumulative impairment			23,100,000	$ 23,100,000
Products and Systems
Goodwill
Goodwill impairment charge		$ 13,200,000	13,197,000
Goodwill, cumulative impairment			13,200,000	13,200,000
International
Goodwill
Goodwill impairment charge			0
Goodwill, cumulative impairment			$ 9,900,000	$ 9,900,000

Intangible Assets - Gross Carry

Intangible Assets - Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 202,774	$ 155,441
Accumulated Amortization	(91,379)	(89,089)
Impairment		(2,613)
Net Carrying Amount	111,395	63,739
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Amount	112,624	113,299
Accumulated Amortization	(60,993)	(58,107)
Impairment		(170)
Net Carrying Amount	$ 51,631	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]
Useful Life (Years)	3 years
Gross Amount	$ 67,240	19,523
Accumulated Amortization	(13,319)	(14,133)
Impairment		(2,411)
Net Carrying Amount	$ 53,921	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	$ 12,593	12,510
Accumulated Amortization	(10,825)	(10,438)
Impairment		0
Net Carrying Amount	$ 1,768	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	$ 10,317	10,109
Accumulated Amortization	(6,242)	(6,411)
Impairment		(32)
Net Carrying Amount	$ 4,075	$ 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

Intangible Assets - Narrative (

Intangible Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	7 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization of expense of intangible assets		$ 5.2	$ 10.2	$ 9	$ 9.6
Software/Technology
Finite-Lived Intangible Assets [Line Items]
Amortization of expense of intangible assets		$ 0.5	$ 1.4	1.2	$ 1
Software/Technology | Products and Systems
Finite-Lived Intangible Assets [Line Items]
Impairment of finite-lived intangible assets	$ 2.6			2.4
Customer relationships | Products and Systems
Finite-Lived Intangible Assets [Line Items]
Impairment of finite-lived intangible assets				0.2
Other | Products and Systems
Finite-Lived Intangible Assets [Line Items]
Impairment of finite-lived intangible assets				$ 0.1

Intangible Assets - Expected Am

Intangible Assets - Expected Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
2019	$ 13,735
2020	12,368
2021	11,292
2022	10,722
2023	9,946
Thereafter	53,332
Net Carrying Amount	$ 111,395	$ 63,739

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued salaries, wages and related employee benefits	$ 29,959	$ 27,185
Contingent consideration	1,687	3,430
Accrued workers' compensation and health benefits	5,086	5,181
Deferred revenues	5,046	6,338
Legal settlement accrual	0	1,600
Pension accrual	5,585	0
Other accrued expenses	26,532	21,827
Total accrued expenses and other current liabilities	$ 73,895	$ 65,561

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt	$ 290,620	$ 166,878
Less: Current portion	(6,833)	(2,358)
Long-term debt, net of current portion	283,787	164,520
Senior credit facility
Debt Instrument [Line Items]
Total debt	181,656	156,948
Senior credit facility | Senior Secured Term Loan
Debt Instrument [Line Items]
Total debt	99,897	0
Debt issuance costs	100
Notes payable
Debt Instrument [Line Items]
Total debt	68	228
Other
Debt Instrument [Line Items]
Total debt	$ 8,999	$ 9,702

Long-Term Debt - Narrative (Det

Long-Term Debt - Narrative (Details)	Dec. 08, 2017USD ($)quarter	Dec. 31, 2018USD ($)	Dec. 13, 2018USD ($)	Dec. 31, 2017USD ($)	Oct. 30, 2014USD ($)
Long-Term Debt
Other debt outstanding		$ 290,620,000		$ 166,878,000
Senior credit facility
Long-Term Debt
Maximum borrowing capacity			$ 300,000,000		$ 250,000,000
Higher borrowing capacity option			450,000,000
Maximum borrowing capacity in non-U.S. Dollar currencies			100,000,000
Maximum amount available for the issuance of letters of credit			20,000,000
Total borrowings outstanding		281,700,000
Outstanding letters of credit		5,400,000
Capitalized debt modification costs		1,100,000
Non-recurring charges threshold used for calculation of funded debt leverage ratio	$ 10,000,000
Number of consecutive fiscal quarters used for calculating funded debt leverage ratio | quarter	4
Funded debt leverage ratio at which the entity will bear the maximum interest rate margin	3.25
Additional interest rate margin if funded debt leverage ratio exceeds threshold (as a percent)	2.00%
Preceding period used for calculating interest coverage ratio	12 months
Number of quarters for temporarily increase in funded debt leverage ratio following business acquisitions | quarter	4
Other debt outstanding		181,656,000		156,948,000
Senior credit facility | Minimum
Long-Term Debt
Funded debt leverage ratio for additional interest payment	3.50
Interest coverage ratio	1.25
Funded debt leverage ratio temporarily increase due to business acquisitions	3.5
Senior credit facility | Maximum
Long-Term Debt
Funded debt leverage ratio at which the entity will have the benefit of lowest interest margin	1
Funded debt leverage ratio for additional interest payment	4.25
Funded debt leverage ratio temporarily increase due to business acquisitions	4
Senior credit facility | LIBOR
Long-Term Debt
Reference rate, description	LIBOR
Senior credit facility | LIBOR | Minimum
Long-Term Debt
Margin rate (as a percent)	1.00%
Senior credit facility | LIBOR | Maximum
Long-Term Debt
Margin rate (as a percent)	2.00%
Senior credit facility | Base rate
Long-Term Debt
Reference rate, description	base rate
Senior credit facility | Base rate | Minimum
Long-Term Debt
Margin rate (as a percent)	(1.25%)
Senior credit facility | Base rate | Maximum
Long-Term Debt
Margin rate (as a percent)	(0.375%)
Senior credit facility | Term A Loan Facility
Long-Term Debt
Maximum borrowing capacity			$ 100,000,000
Other debt outstanding		$ 99,897,000		0
Notes payable
Long-Term Debt
Maturity term from the date of acquisition		3 years
Interest rate, minimum (as a percent)		3.95%
Other debt outstanding		$ 68,000		228,000
Other
Long-Term Debt
Other debt outstanding		$ 8,999,000		$ 9,702,000
Other | Minimum
Long-Term Debt
Interest rate, minimum (as a percent)		0.60%
Monthly debt payments		$ 1,000
Other | Maximum
Long-Term Debt
Interest rate, minimum (as a percent)		6.20%
Monthly debt payments		$ 17,000

Long-Term Debt - Scheduled Prin

Long-Term Debt - Scheduled Principal Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2019	$ 6,831
2020	6,515
2021	8,750
2022	11,030
2023	255,043
Thereafter	2,451
Total debt	$ 290,620	$ 166,878

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Contingent Consideration Liability [Roll Forward]
Revaluation	$ 262	$ (716)	$ (463)	$ (2,066)
Level 3
Contingent Consideration Liability [Roll Forward]
Contingent consideration, beginning balance		5,508	3,094
Acquisitions		0	3,407
Payments		(2,277)	(560)
Accretion of liability		175	272
Revaluation		(891)	(735)
Foreign currency translation		(150)	30
Contingent consideration, ending balance	$ 3,094	$ 2,365	$ 5,508

Share-Based Compensation - Long

Share-Based Compensation - Long-term Incentive Plans (Details)	12 Months Ended
	Dec. 31, 2018planshares	Dec. 31, 2017shares	Dec. 31, 2016shares	May 31, 2016shares	May 31, 2015shares
Share-based compensation
Stock options outstanding (in shares)	2,105,000	2,130,000	2,167,000	2,232,000	2,287,000
Restricted Stock Units
Share-based compensation
Unvested restricted stock units outstanding (in shares)	443,000	532,000	569,000	575,000	564,000
2007 Plan and 2009 Plan
Share-based compensation
Number of employee stock ownership plans | plan	3
Number of awards authorized for grants (in shares)	0
2007 Plan and 2009 Plan | Stock Options
Share-based compensation
Stock options outstanding (in shares)	2,105,000
2007 Plan and 2009 Plan | Restricted Stock Units
Share-based compensation
Unvested restricted stock units outstanding (in shares)	452,000
2016 Plan
Share-based compensation
Number of awards authorized for grants (in shares)	1,700,000
Number of awards available for future grants (in shares)	1,143,000

Share-Based Compensation - Stoc

Share-Based Compensation - Stock Options Narrative (Details) - USD ($)	7 Months Ended	12 Months Ended			19 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016	Dec. 31, 2016
Share-based compensation
Stock options granted (in shares)	0	0	0	0
Unrecognized compensation costs related to stock options		$ 0
Stock Options
Share-based compensation
Recognized share-based compensation expense	$ 0	$ 0	$ 0		$ 100,000
Stock options granted (in shares)	0		0	0

Share-Based Compensation - Cash

Share-Based Compensation - Cash Proceeds and Intrinsic Value of Stock Options Exercised (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Cash proceeds from options exercised	$ 604	$ 273	$ 275	$ 543
Aggregate intrinsic value of options exercised	$ 993	$ 277	$ 580	$ 658

Share-Based Compensation - St_2

Share-Based Compensation - Stock Option Activity (Details) - $ / shares	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Common Stock Options (shares)
Outstanding at beginning of year: (in shares)	2,232,000	2,130,000	2,167,000	2,287,000
Granted (in shares)	0	0	0	0
Exercised (in shares)	(65,000)	(25,000)	(37,000)	(55,000)
Expired or forfeited (in shares)	0	0	0	0
Outstanding at end of year: (in shares)	2,167,000	2,105,000	2,130,000	2,232,000
Weighted Average Exercise Price (in dollar per share)
Outstanding at beginning of year: (in dollars per share)	$ 13.21	$ 13.43	$ 13.33	$ 13.13
Granted (in dollars per share)	0	0	0	0
Exercised (in dollars per share)	9.27	10.75	7.39	9.87
Expired or forfeited (in dollars per share)	0	0	0	0
Outstanding at end of year: (in dollars per share)	$ 13.33	$ 13.47	$ 13.43	$ 13.21

Share-Based Compensation - St_3

Share-Based Compensation - Stock Options Outstanding and Exercisable (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Options Outstanding
Total Options Outstanding (in shares) | shares	2,105
Options Exercisable
Number Exercisable (in shares) | shares	2,105
Aggregate Intrinsic Value
Options Outstanding (in dollars) | $	$ 1,965
Options Exercisable (in dollars) | $	$ 1,965
$10.00-$10.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 10
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 10
Options Outstanding
Total Options Outstanding (in shares) | shares	10
Weighted Average Remaining Life (Years)	3 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 10
Options Exercisable
Number Exercisable (in shares) | shares	10
Weighted Average Exercise Price (in dollars per share)	$ 10
$13.46-$22.35
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Lower Limit (in dollars per share)	13.46
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 22.35
Options Outstanding
Total Options Outstanding (in shares) | shares	2,095
Weighted Average Remaining Life (Years)	8 months 12 days
Weighted Average Exercise Price (in dollars per share)	$ 13.48
Options Exercisable
Number Exercisable (in shares) | shares	2,095
Weighted Average Exercise Price (in dollars per share)	$ 13.48

Share-Based Compensation - Rest

Share-Based Compensation - Restricted Stock Units Awards Narrative (Details) - Restricted Stock Units - USD ($) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Share-based compensation
Recognized share-based compensation expense	$ 2.6	$ 4.2	$ 4.5	$ 4.4
Unrecognized compensation cost, net of estimated forfeitures, related to restricted stock unit awards		$ 6.8
Weighted-average period over which unrecognized compensation cost is expected to be recognized		2 years 4 months 24 days

Share-Based Compensation - Vest

Share-Based Compensation - Vesting Activity of Restricted Stock Unit Awards (Details) - Restricted Stock Units - USD ($) shares in Thousands, $ in Millions	7 Months Ended	12 Months Ended			19 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016	Dec. 31, 2016
Share-based compensation
Restricted stock awards vested	207	258	185	223	223
Fair value of awards vested	$ 5.1	$ 5.3	$ 3.4		$ 3.5

Share-Based Compensation - Comm

Share-Based Compensation - Common Stock Issued to Non-employee Directors (Details) - Non-employee directors - Common Stock shares in Thousands, $ in Millions	7 Months Ended	12 Months Ended		19 Months Ended
	Dec. 31, 2016USD ($)shares	Dec. 31, 2018USD ($)directorshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares
Share-based compensation
Number of non-employee directors to whom fully vested common stock is granted | director		5
Awards issued (in shares) | shares	10	19	21	28
Grant date fair value of awards issued (in dollars per share) | $	$ 0.3	$ 0.4	$ 0.4	$ 0.5

Share-Based Compensation - Re_2

Share-Based Compensation - Restricted Stock Unit Awards Outstanding (Details) - Restricted Stock Units - $ / shares shares in Thousands	7 Months Ended	12 Months Ended			19 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016	Dec. 31, 2016	May 31, 2015
Units
Outstanding at beginning of period: (in shares)	575	532	569	564	564
Granted (in shares)	219	211	183	264
Released (in shares)	(207)	(258)	(185)	(223)	(223)
Forfeited (in shares)	(18)	(42)	(35)	(30)
Outstanding at end of period: (in shares)	569	443	532	575	569
Weighted Average Grant-Date Fair Value
Outstanding at beginning of period: (in dollars per share)	$ 20.81	$ 20.55	$ 21.05	$ 18.85	$ 20.81	$ 20.47
Granted (in dollars per share)	24.48	19.20	21.26	16.73
Released (in dollars per share)	19.40	20.48	20.49	20.40
Forfeited (in dollars per share)	19.55	20.52	21.45	19.26
Outstanding at end of period: (in dollars per share)	$ 20.81	$ 20.55	$ 21.05	$ 18.85	$ 20.81	$ 20.47

Share-Based Compensation - Perf

Share-Based Compensation - Performance Restricted Stock Units Narrative (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended			7 Months Ended	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Aug. 31, 2015	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016	May 31, 2015	May 31, 2014
PRSUs
Share-based compensation
Number of restricted stocks units granted (in shares)				105	129	128
Unvested restricted stock units outstanding (in shares)				290	277	278	328
PRSUs | Executive and senior officers
Share-based compensation
Number of fully vested common stock granted (in shares)			154
Unvested restricted stock units outstanding (in shares)					309
Recognized share-based compensation expense				$ 1.7	$ 1.5	$ 1.7	$ 1.6
Unrecognized compensation cost, net of estimated forfeitures, related to restricted stock unit awards					$ 1.8
Weighted-average period over which unrecognized compensation cost is expected to be recognized					1 year 10 months 24 days
Income tax benefit recognized on share-based compensation				1.6	$ 1	2.2	$ 2.2
PRSUs | Fiscal 2014 Grants | Executive and senior officers
Share-based compensation
Requisite service period									3 years
PRSUs | Fiscal 2015 Grants | Executive and senior officers
Share-based compensation
Requisite service period								3 years
PRSUs | Fiscal 2016 Grants | Executive and senior officers
Share-based compensation
Requisite service period							5 years
Increase in number of shares authorized for grant (in shares)							104
Number of awards authorized for grants (in shares)							258
PRSUs | Transition Period Ended December 31, 2016 Grants | Accrued Expenses and Other Current Liabilities
Share-based compensation
Aggregate liability related to performance shares outstanding				$ 0.1
PRSUs | Transition Period Ended December 31, 2016 Grants | Executive and senior officers
Share-based compensation
Number of restricted stocks units granted (in shares)				105
Increase (reduction) in number of shares authorized for grant (in shares)		(3)		(73)
Unvested restricted stock units outstanding (in shares)				12
PRSUs | Fiscal 2017 Grants | Accrued Expenses and Other Current Liabilities
Share-based compensation
Aggregate liability related to performance shares outstanding						$ 0.1
PRSUs | Fiscal 2017 Grants | Executive and senior officers
Share-based compensation
Number of restricted stocks units granted (in shares)						128
Increase (reduction) in number of shares authorized for grant (in shares)	4					(65)
Unvested restricted stock units outstanding (in shares)						13
PRSUs | Fiscal 2018 Grants | Accrued Expenses and Other Current Liabilities
Share-based compensation
Aggregate liability related to performance shares outstanding					$ 0.1
PRSUs | Fiscal 2018 Grants | Executive and senior officers
Share-based compensation
Number of restricted stocks units granted (in shares)					129
Increase (reduction) in number of shares authorized for grant (in shares)					(54)
Unvested restricted stock units outstanding (in shares)					22
PRSUs with one year performance condition | Fiscal 2014 Grants | Executive and senior officers
Share-based compensation
Award performance period									1 year
PRSUs with two year performance condition | Fiscal 2014 Grants | Executive and senior officers
Share-based compensation
Award performance period									2 years
PRSUs with three years performance condition | Executive and senior officers
Share-based compensation
Payout performance period					1 year
Requisite service period					5 years
PRSUs with three years performance condition | Executive and senior officers | 1st Anniversary
Share-based compensation
Vesting period					4 years
PRSUs with three years performance condition | Executive and senior officers | 2nd Anniversary
Share-based compensation
Vesting period					2 years
PRSUs with three years performance condition | Executive and senior officers | 3rd Anniversary
Share-based compensation
Vesting period					3 years
PRSUs with three years performance condition | Executive and senior officers | 4th Anniversary
Share-based compensation
Vesting period					4 years
PRSUs with three years performance condition | Fiscal 2014 Grants | Executive and senior officers
Share-based compensation
Award performance period									3 years
PRSUs with three years performance condition | Fiscal 2015 Grants | Executive and senior officers
Share-based compensation
Award performance period								3 years
PRSUs with one year market condition | Fiscal 2014 Grants | Executive and senior officers
Share-based compensation
Award performance period				1 year					1 year
Payout for the fiscal 2014 market condition awards, percentage of target				170.00%
PRSUs with two year market condition | Fiscal 2014 Grants | Executive and senior officers
Share-based compensation
Award performance period				2 years					2 years
Payout for the fiscal 2014 market condition awards, percentage of target				105.00%
PRSUs with three years of performance and market conditions | Fiscal 2014 Grants | Executive and senior officers
Share-based compensation
Award performance period			3 years	3 years
PRSUs with three years of performance and market conditions | Fiscal 2015 Grants | Executive and senior officers
Share-based compensation
Award performance period			3 years

Share-Based Compensation - Pe_2

Share-Based Compensation - Performance Restricted Stock Units Activity (Details) - PRSUs - $ / shares shares in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
Units
Outstanding at beginning of period: (in shares)	328	278	290
Granted (in shares)	105	129	128
Performance condition adjustments, net (in shares)	(54)	(50)	(68)
Released (in shares)	(89)	(68)	(72)
Forfeited (in shares)	0	(12)	0
Outstanding at end of period: (in shares)	290	277	278	328
Weighted Average Grant-Date Fair Value
Outstanding at beginning of period: (in dollars per share)	$ 16.01	$ 17.80	$ 17	$ 17.02
Granted (in dollars per share)	24.90	19.46	20.42
Performance condition adjustments, net (in dollars per share)	24.49	19.48	20.55
Released (in dollars per share)	24.50	16.03	15.82
Forfeited (in dollars per share)	0	16.16	0
Outstanding at end of period: (in dollars per share)	$ 16.01	$ 17.80	$ 17	$ 17.02

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	7 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Income (loss) before provision for income taxes from:
U.S. operations	$ 5,116		$ 9,853	$ (7,303)		$ 27,772
Foreign operations	10,365		4,418	7,077		10,643
Income (loss) before provision for income taxes	15,481	$ 31,426	14,271	(226)	$ 22,471	38,415
Current
Federal	1,990		790	3,558		9,156
States and local	483		533	39		1,537
Foreign	3,569		3,824	3,131		3,672
Reserve for uncertain tax positions	(39)		337	71		(529)
Total current	6,003		5,484	6,799		13,836
Deferred
Federal	6		2,966	(3,857)		82
States and local	(28)		399	(810)		(51)
Foreign	(514)		(2,089)	(437)		(557)
Total deferred	(536)		1,276	(5,104)		(526)
Net change in valuation allowance	403		666	247		455
Net deferred	(133)		1,942	(4,857)		(71)
Provision for income taxes	$ 5,870	$ 11,627	$ 7,426	$ 1,942	$ 8,008	$ 13,765

Income Taxes - Tax Rate Reconci

Income Taxes - Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	7 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal tax at statutory rate	$ 5,418		$ 2,997	$ (79)		$ 13,445
State taxes, net of federal benefit	296		737	(502)		966
Foreign tax	(573)		807	217		(610)
Contingent consideration	(4)		(6)	(63)		(425)
Nondeductible compensation	0		183	0
US taxation of foreign earnings	0		228	0
Permanent differences	373		361	377		245
Transition tax, net of foreign tax credits	0		1,158	3,942
Federal tax rate change due to the Tax Act	0		87	(1,956)
Other	(43)		208	(241)		(311)
Change in valuation allowance	403		666	247		455
Provision for income taxes	$ 5,870	$ 11,627	$ 7,426	$ 1,942	$ 8,008	$ 13,765
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal tax at statutory rate	35.00%		21.00%	35.00%		35.00%
State taxes, net of federal benefit	1.90%		5.10%	221.60%		2.50%
Foreign tax	(3.70%)		5.70%	(95.80%)		(1.60%)
Contingent consideration	0.00%		0.00%	27.70%		(1.10%)
Nondeductible compensation	0.00%		1.30%	0.00%
US taxation of foreign earnings	0.00%		1.60%	0.00%
Permanent differences	2.40%		2.50%	(166.40%)		0.60%
Transition tax, net of foreign tax credits	0.00%		8.10%	(1741.40%)
Federal tax rate change due to the Tax Act	0.00%		0.60%	864.00%
Other	(0.30%)		1.40%	106.50%		(0.80%)
Change in valuation allowance	2.60%		4.70%	(109.10%)		1.20%
Provision for income taxes	37.90%		52.00%	(857.90%)		35.80%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended												7 Months Ended		12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Operating Loss Carryforwards [Line Items]
Income tax expense related to the Tax Act																$ 1,900,000
Provisional one-time benefit as result of remeasurement of federal deferred tax assets and liabilities																2,300,000
Provisional one-time expense due to imposition of transition tax																3,900,000
Provisional tax expense attributable to reduction in deferred tax assets																300,000
Complete accounting, income tax expense for effects of Tax Act															$ 1,700,000
Complete accounting, tax expense due to increase of net deferred tax liabilities															100,000
Complete accounting, tax expense due to transition tax															1,300,000
Tax expense due to changes made to executive compensation rules pursuant to Tax Act															400,000
Tax expense due to GILTI															200,000
Tax expense due to additional non-deductible items															300,000
Deferred tax assets valuation allowance	$ 4,235,000				$ 4,044,000										4,235,000	4,044,000
Unrecognized tax benefits including penalties and interest, that would affect the effective tax rate, if recognized	700,000				200,000										700,000	200,000
Anticipated decrease in unrecognized tax benefits, excluding interest and penalties within the next 12 months	500,000														500,000
Net income (loss) of foreign subsidiaries	(1,061,000)	$ (1,010,000)	$ 6,000,000	$ 2,919,000	884,000	$ (6,968,000)	$ 2,217,000	$ 1,692,000	$ 963,000	$ 7,238,000	$ 2,761,000	$ 3,447,000	$ 9,568,000	$ 19,814,000	6,836,000	(2,175,000)	$ 14,409,000	$ 24,654,000
Recognized a deferred tax liability on undistributed international earnings (losses) of foreign subsidiaries	0														0
Unrecorded deferred tax liability related to undistributed international earnings	1,000,000														1,000,000
State
Operating Loss Carryforwards [Line Items]
Net operating losses	25,000,000														25,000,000
Foreign
Operating Loss Carryforwards [Line Items]
Net operating losses	11,000,000														11,000,000
Net income (loss) of foreign subsidiaries													$ 6,900,000		2,000,000	4,100,000		$ 7,500,000
Foreign | Expiration Period 2025-2038
Operating Loss Carryforwards [Line Items]
Net operating losses	800,000														800,000
State and Foreign
Operating Loss Carryforwards [Line Items]
Increase in deferred tax assets valuation allowance															200,000
State and Foreign | Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations | Disposal of Foreign Subsidiaries
Operating Loss Carryforwards [Line Items]
Deferred tax assets valuation allowance	4,200,000				$ 4,000,000										4,200,000	$ 4,000,000
Internal Revenue Service (IRS) | Federal
Operating Loss Carryforwards [Line Items]
Net operating losses	$ 300,000														$ 300,000

Income Taxes - Deferred Income

Income Taxes - Deferred Income Tax (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax assets
Allowance for doubtful accounts	$ 951	$ 838
Inventory	285	265
Intangible assets	1,230	2,255
Accrued expenses	4,408	2,560
Net operating loss carryforward	3,889	3,729
Capital lease obligations	731	1,004
Capital losses	462	463
Foreign tax credit carryover	0	618
Deferred share-based compensation	3,728	4,080
Other	699	484
Deferred income tax assets	16,383	16,296
Valuation allowance	(4,235)	(4,044)
Net deferred income tax assets	12,148	12,252
Deferred income tax liabilities
Property and equipment	(7,597)	(6,893)
Goodwill	(9,302)	(6,578)
Intangible assets	(16,459)	(5,972)
Other	(8)	(6)
Deferred income tax liabilities	(33,366)	(19,449)
Net deferred income taxes	$ (21,218)	$ (7,197)

Income Taxes - Changes in Unrec

Income Taxes - Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 156	$ 267
Additions for tax positions related to the current fiscal period	1	11
Additions for tax positions related to prior years	341	188
Decreases for tax positions related to prior years	(2)	0
Current year acquisitions	270	0
Impact of foreign exchange fluctuation	0	10
Settlements	(4)	(198)
Reductions related to the expiration of statutes of limitations	(39)	(122)
Balance at end of period	$ 723	$ 156

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	May 31, 2016
401(k) savings plan
Minimum age for employees to contribute catch up contributions under IRS limits		50 years
Continuous service period required for eligibility of employees to participate under the plan		3 months
Maximum Company match amount of employee contributions matched up to 6% of annual compensation (as a percent)		50.00%
Maximum percentage of employee's annual compensation for which the company contributes a matching contribution (as a percent)		6.00%
Vesting period for employer matching contribution		5 years
Contribution under 401(k) savings plan	$ 2	$ 3.9	$ 3.7	$ 3.5
Multiemployer Plans, Pension | Boilermakers and Pipefitters Plans
Multiemployer Defined Benefit Pension Plans
Multiemployer plan funded status		Between 65 and less than 80 percent
Multiemployer plan, amount of Company's contributions	$ 1.5	$ 0.6	$ 2.4	$ 2.5
Multiemployer plan, Company's contributions as percentage of total		5.00%

Related Party Transactions (Det

Related Party Transactions (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)director	Aug. 17, 2016shares
Shareholder and officer
Related Party Transactions
Total rent payments	$ 1
Non-employee directors | Capital Management Enterprise (“CME”) | Consulting Services
Related Party Transactions
Number of non-employee director | director	1
France | Shareholder and officer
Related Party Transactions
Total rent payments	$ 0.1
Brazil | Shareholder and officer
Related Party Transactions
Total rent payments	$ 0.1
Stock Repurchase Plan | Chairman and CEO
Related Party Transactions
Number of shares authorized to be repurchased (in shares) | shares		1,000,000

Obligations under Capital Lea_3

Obligations under Capital Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Capital Leased Assets [Line Items]
Net book value of assets under capital lease	$ 14,600	$ 19,500
Minimum
Capital Leased Assets [Line Items]
Required monthly payments	$ 1
Effective interest rate (as a percent)	1.00%
Maximum
Capital Leased Assets [Line Items]
Required monthly payments	$ 63
Effective interest rate (as a percent)	11.00%

Obligations under Capital Lea_4

Obligations under Capital Leases - Future Minimum Capital Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
2019	$ 4,686
2020	3,489
2021	2,757
2022	1,475
2023	807
Thereafter	773
Total minimum lease payments	13,987
Less: amount representing interest	(990)
Present value of minimum lease payments	12,997
Less: current portion of obligations under capital leases	(3,922)	$ (5,875)
Obligations under capital leases, net of current portion	$ 9,075	$ 8,738

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Operating Lease Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 10,939
2020	8,764
2021	6,327
2022	4,826
2023	4,239
Thereafter	10,667
Total	$ 45,762

Commitments and Contingencies_2

Commitments and Contingencies - Narrative (Details)	1 Months Ended			7 Months Ended		12 Months Ended
	Jan. 31, 2018USD ($)	Apr. 30, 2017	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2018USD ($)employeeclaim	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	May 31, 2016USD ($)
Litigation
Total rent expense				$ 6,600,000		$ 12,300,000	$ 11,800,000		$ 11,200,000
Legal settlement charges				$ 0	$ 0	$ 0	1,600,000	$ 6,320,000	$ 6,320,000
Period over which potential acquisition-related contingent consideration would be payable						1 year 6 months
Dispute with former owner of company's French subsidiary | French Subsidiary | AGL Services Company v Mistras Group, Inc.
Litigation
Litigation settlement amount								$ 400,000
Damages from product defects | Triumph Aerostructures-Vought Aircraft Division v Mistras Group, Inc.
Litigation
Litigation settlement amount	$ 1,600,000
Verbal demand for damages			$ 2,300,000
Legal settlement charges							$ 1,600,000
Company vehicle accident | McAllister v. Mistras Group, Inc.
Litigation
Number of claims filed | claim						1
Pension related contingencies
Litigation
Potential withdrawal liability related to withdrawal from multiemployer pension plans						$ 5,900,000
Acquisition-related contingencies
Litigation
Potential acquisition-related contingent consideration, low end of range						0
Potential acquisition-related contingent consideration, high end of range						5,800,000
Selling, General and Administrative Expenses | NDT Do Brazil, LTDA | Severance and labor disputes
Litigation
Contingency related charges						$ 1,200,000
GERMANY | Severance and labor disputes | French Subsidiary
Litigation
Period covered by temporary staff leasing contract		18 months
Number of employees under staff leasing contract | employee						200
GERMANY | Selling, General and Administrative Expenses | Severance and labor disputes | French Subsidiary
Litigation
Contingency related charges						$ 1,600,000

Segment Disclosure - Financial

Segment Disclosure - Financial Information (Details) $ in Thousands	3 Months Ended												7 Months Ended		12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2018USD ($)Operating_Segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	May 31, 2016USD ($)
Segment Reporting [Abstract]
Number of operating segments | Operating_Segment															3
Financial information by segment
Revenues													$ 404,161	$ 427,913	$ 742,354	$ 700,970	$ 684,762	$ 719,181
Gross profit	$ 52,315	$ 52,332	$ 55,083	$ 48,145	$ 50,319	$ 47,897	$ 46,343	$ 43,153	$ 47,978	$ 50,651	$ 51,535	$ 43,970	117,004	123,190	207,874	187,712	194,134	203,008
Income from operations	2,502	$ 3,017	$ 8,409	$ 6,399	6,282	$ (10,375)	$ 5,003	$ 3,250	$ 2,944	$ 12,116	$ 4,840	$ 5,646	17,533	$ 35,098	22,221	4,160	$ 25,546	43,177
Depreciation and amortization													19,199		34,413	31,383		32,474
Intangible assets, net	111,395				63,739										111,395	63,739
Total assets	694,037				554,441										694,037	554,441
Operating segments | Services
Financial information by segment
Revenues													293,218		574,619	543,565		553,279
Gross profit													75,784		151,974	139,160		145,262
Income from operations													22,411		47,126	46,677		52,552
Depreciation and amortization													12,765		24,079	21,649		22,725
Intangible assets, net	98,362				46,864										98,362	46,864
Total assets	523,506				377,585										523,506	377,585
Operating segments | International
Financial information by segment
Revenues													104,013		153,448	144,265		143,025
Gross profit													34,210		45,464	38,974		43,613
Income from operations													10,597		3,953	3,537		9,293
Depreciation and amortization													5,306		8,846	7,768		7,774
Intangible assets, net	11,143				13,899										11,143	13,899
Total assets	146,535				150,779										146,535	150,779
Operating segments | Products and Systems
Financial information by segment
Revenues													14,541		23,426	23,297		30,293
Gross profit													6,920		10,560	9,798		14,022
Income from operations													(254)		2,368	(16,991)		2,688
Depreciation and amortization													1,372		1,429	2,180		2,323
Intangible assets, net	1,438				2,261										1,438	2,261
Total assets	12,264				12,733										12,264	12,733
Corporate and eliminations
Financial information by segment
Revenues													(7,611)		(9,139)	(10,157)		(7,416)
Gross profit													90		(124)	(220)		111
Income from operations													(15,221)		(31,226)	(29,063)		(21,356)
Depreciation and amortization													$ (244)		59	(214)		$ (348)
Intangible assets, net	452				715										452	715
Total assets	$ 11,732				$ 13,344										$ 11,732	$ 13,344

Segment Disclosure - Revenue an

Segment Disclosure - Revenue and Long-lived Assets (Details) - USD ($) $ in Thousands	7 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Revenue and long-lived assets by geographic area
Revenue	$ 404,161	$ 427,913	$ 742,354	$ 700,970	$ 684,762	$ 719,181
Long-lived assets			484,549	354,320
United States
Revenue and long-lived assets by geographic area
Revenue	256,926		487,414	466,683		519,361
Long-lived assets			230,140	237,616
Other Americas
Revenue and long-lived assets by geographic area
Revenue	41,777		98,248	86,870		67,809
Long-lived assets			177,628	36,011
Europe
Revenue and long-lived assets by geographic area
Revenue	91,847		143,312	132,421		118,566
Long-lived assets			76,781	80,693
Asia-Pacific
Revenue and long-lived assets by geographic area
Revenue	$ 13,611		$ 13,380	$ 14,996		$ 13,445

Repurchase of Common Stock (Det

Repurchase of Common Stock (Details) - USD ($)	Aug. 17, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2018	Oct. 07, 2015
Class of Stock [Line Items]
Treasury stock acquired, aggregate cost		$ 9,000,000	$ 15,923,000
Stock Repurchase Plan
Class of Stock [Line Items]
Stock repurchase plan, amount approved					$ 50,000,000
Treasury stock repurchased (in shares)		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
Stock Repurchase Plan | 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)		274,000	726,000	1,000,000
Treasury stock acquired, average price (in dollars per share)		$ 21.90	$ 21.93	$ 21.92
Treasury stock acquired, aggregate cost		$ 6,000,000	$ 15,900,000	$ 21,900,000

Twelve Months Ended December _3

Twelve Months Ended December 31, 2016 and Seven Months Ended December 31, 2015 Comparative Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended												7 Months Ended		12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenues													$ 404,161	$ 427,913	$ 742,354	$ 700,970	$ 684,762	$ 719,181
Cost of revenue													274,298	292,718	512,024	492,238	468,929	494,911
Depreciation													12,859	12,005	22,456	21,020	21,699	21,262
Gross profit	$ 52,315	$ 52,332	$ 55,083	$ 48,145	$ 50,319	$ 47,897	$ 46,343	$ 43,153	$ 47,978	$ 50,651	$ 51,535	$ 43,970	117,004	123,190	207,874	187,712	194,134	203,008
Selling, general and administrative expenses													91,058	81,117	166,352	153,025	148,914	141,229
Research and engineering													1,577	1,431	3,310	2,272	2,670	2,523
Depreciation and amortization													6,340	6,503	11,957	10,363	10,689	11,212
Litigation charges													0	0	0	1,600	6,320	6,320
Acquisition-related benefit, net													496	(959)	532	482	(5)	(1,453)
Income from operations	2,502	3,017	8,409	6,399	6,282	(10,375)	5,003	3,250	2,944	12,116	4,840	5,646	17,533	35,098	22,221	4,160	25,546	43,177
Interest expense, net														3,672			3,075
Income (loss) before provision for income taxes													15,481	31,426	14,271	(226)	22,471	38,415
Provision for income taxes													5,870	11,627	7,426	1,942	8,008	13,765
Net income (loss)													9,611	19,799	6,845	(2,168)	14,463	24,650
Less: Net income (loss) attributable to non-controlling interests													43	(15)	9	7	54	(4)
Net income (loss) attributable to Mistras Group, Inc.	$ (1,061)	$ (1,010)	$ 6,000	$ 2,919	$ 884	$ (6,968)	$ 2,217	$ 1,692	$ 963	$ 7,238	$ 2,761	$ 3,447	$ 9,568	$ 19,814	$ 6,836	$ (2,175)	$ 14,409	$ 24,654
Basic (in dollars per share)	$ (0.04)	$ (0.04)	$ 0.21	$ 0.10	$ 0.03	$ (0.25)	$ 0.08	$ 0.06	$ 0.03	$ 0.25	$ 0.10	$ 0.12	$ 0.33	$ 0.69	$ 0.24	$ (0.08)	$ 0.50	$ 0.85
Diluted (in dollars per share)	$ (0.04)	$ (0.04)	$ 0.20	$ 0.10	$ 0.03	$ (0.25)	$ 0.07	$ 0.06	$ 0.03	$ 0.24	$ 0.09	$ 0.11	$ 0.32	$ 0.67	$ 0.23	$ (0.08)	$ 0.48	$ 0.82
Weighted average common shares outstanding:
Basic (in shares)													28,989	28,810	28,406	28,422	28,960	28,856
Diluted (in shares)													30,125	29,676	29,427	28,422	30,114	29,891

Selected Quarterly Financial _3

Selected Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												7 Months Ended		12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 180,762	$ 182,169	$ 191,793	$ 187,630	$ 187,643	$ 179,570	$ 170,439	$ 163,318	$ 170,156	$ 168,811	$ 178,340	$ 167,455
Gross Profit	52,315	52,332	55,083	48,145	50,319	47,897	46,343	43,153	47,978	50,651	51,535	43,970	$ 117,004	$ 123,190	$ 207,874	$ 187,712	$ 194,134	$ 203,008
Income from operations	2,502	3,017	8,409	6,399	6,282	(10,375)	5,003	3,250	2,944	12,116	4,840	5,646	17,533	35,098	22,221	4,160	25,546	43,177
Net income (loss) attributable to Mistras Group, Inc.	$ (1,061)	$ (1,010)	$ 6,000	$ 2,919	$ 884	$ (6,968)	$ 2,217	$ 1,692	$ 963	$ 7,238	$ 2,761	$ 3,447	$ 9,568	$ 19,814	$ 6,836	$ (2,175)	$ 14,409	$ 24,654
Earnings per common share:
Basic (in dollars per share)	$ (0.04)	$ (0.04)	$ 0.21	$ 0.10	$ 0.03	$ (0.25)	$ 0.08	$ 0.06	$ 0.03	$ 0.25	$ 0.10	$ 0.12	$ 0.33	$ 0.69	$ 0.24	$ (0.08)	$ 0.50	$ 0.85
Diluted (in dollars per share)	$ (0.04)	$ (0.04)	$ 0.20	$ 0.10	$ 0.03	$ (0.25)	$ 0.07	$ 0.06	$ 0.03	$ 0.24	$ 0.09	$ 0.11	$ 0.32	$ 0.67	$ 0.23	$ (0.08)	$ 0.48	$ 0.82