Document and Entity Information - USD ($) $ in Millions	7 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2016	Mar. 08, 2017	Jun. 30, 2016
Document and Entity Information
Entity Registrant Name	Mistras Group, Inc.
Entity Central Index Key	0001436126
Document Type	10-KT
Document Period End Date	Dec. 31, 2016
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 Public Float			$ 408.4
Entity Common Stock, Shares Outstanding		28,671,636
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	FY

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015
Current Assets
Cash and cash equivalents	$ 19,154	$ 21,188	$ 10,555
Accounts receivable, net	130,852	137,913	133,228
Inventories	10,017	9,918	10,841
Deferred income taxes	6,230	6,216	5,144
Prepaid expenses and other current assets	16,399	12,711	11,698
Total current assets	182,652	187,946	171,466
Property, plant and equipment, net	73,149	78,676	79,256
Intangible assets, net	40,007	43,492	51,276
Goodwill	169,940	169,220	166,414
Deferred income taxes	1,086	1,000	1,208
Other assets	2,593	2,341	2,107
Total Assets	469,427	482,675	471,727
Current Liabilities
Accounts payable	6,805	10,796	10,529
Accrued expenses and other current liabilities	58,697	62,983	55,914
Current portion of long-term debt	1,379	12,553	17,902
Current portion of capital lease obligations	6,488	7,835	8,646
Income taxes payable	4,342	2,710	532
Total current liabilities	77,711	96,877	93,523
Long-term debt, net of current portion	85,917	72,456	95,557
Obligations under capital leases, net of current portion	9,682	11,932	10,717
Deferred income taxes	17,584	18,328	16,984
Other long-term liabilities	7,789	6,794	9,934
Total Liabilities	198,683	206,387	226,715
Commitments and contingencies
Equity
Preferred stock, 10,000,000 shares authorized	0	0	0
Common stock, $0.01 par value, 200,000,000 shares authorized, 29,216,745, 28,939,993 and 28,703,320 shares issued	292	290	287
Additional paid-in capital	217,211	213,737	208,064
Treasury stock at cost, 420,258, 0 and 0 shares	(9,000)	0	0
Retained earnings	91,803	82,235	57,581
Accumulated other comprehensive loss	(29,724)	(20,099)	(21,113)
Total Mistras Group, Inc. stockholders’ equity	270,582	276,163	244,819
Noncontrolling interests	162	125	193
Total Equity	270,744	276,288	245,012
Total Liabilities and Equity	$ 469,427	$ 482,675	$ 471,727

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2016	May 31, 2016	May 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000	200,000,000
Common stock, shares issued (in shares)	29,216,745	28,939,993	28,703,320
Treasury stock at cost (in shares)	420,258	0	0

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
Income Statement [Abstract]
Revenue	$ 404,161	$ 719,181	$ 711,252	$ 623,447
Cost of revenue	274,298	494,911	506,281	432,695
Depreciation	12,859	21,262	20,238	17,809
Gross profit	117,004	203,008	184,733	172,943
Selling, general and administrative expenses	91,058	141,229	143,978	123,690
Research and engineering	1,577	2,523	2,521	2,995
Depreciation and amortization	6,340	11,212	13,048	10,620
Acquisition-related expense (benefit), net	496	(1,453)	(5,167)	(2,657)
Legal settlement	0	6,320	0	0
Income from operations	17,533	43,177	30,353	38,295
Interest expense	2,052	4,762	4,622	3,192
Income before provision for income taxes	15,481	38,415	25,731	35,103
Provision for income taxes	5,870	13,765	9,740	12,528
Net income	9,611	24,650	15,991	22,575
Less: net income (loss) attributable to noncontrolling interests, net of taxes	43	(4)	(90)	57
Net income attributable to Mistras Group, Inc.	$ 9,568	$ 24,654	$ 16,081	$ 22,518
Earnings per common share
Basic (in dollars per share)	$ 0.33	$ 0.85	$ 0.56	$ 0.79
Diluted (in dollars per share)	$ 0.32	$ 0.82	$ 0.54	$ 0.77
Weighted average common shares outstanding:
Basic (in shares)	28,989	28,856	28,613	28,365
Diluted (in shares)	30,125	29,891	29,590	29,324

Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 9,611	$ 24,650	$ 15,991	$ 22,575
Other comprehensive (loss) income:
Foreign currency translation adjustments	(9,625)	1,014	(19,602)	2,941
Comprehensive (loss) income	(14)	25,664	(3,611)	25,516
Less: net income (loss) attributable to noncontrolling interests	43	(4)	(90)	57
Foreign currency translation adjustments attributable to noncontrolling interests	6	1	5	(4)
Comprehensive (loss) income attributable to Mistras Group, Inc.	$ (51)	$ 25,669	$ (3,516)	$ 25,455

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, 2013			28,211	0
Balance at May. 31, 2013	$ 210,280	$ 210,053	$ 282	$ 0	$ 195,241	$ 18,982	$ (4,452)	$ 227
Increase (Decrease) in Stockholders' Equity
Net income	22,575	22,518				22,518		57
Other comprehensive (income) loss, net of tax	2,945	2,941					2,941	4
Share-based payments (in shares)			19
Share-based payments	6,261	6,261			6,261
Net settlement on vesting of restricted stock units (in shares)			123
Net settlement on vesting of restricted stock units	(1,006)	(1,006)	$ 1		(1,007)
Excess tax benefit from share-based payment compensation	340	340			340
Exercise of stock options (in shares)			103
Exercise of stock options	997	997	$ 1		996
Balance (in shares) at May. 31, 2014			28,456	0
Balance at May. 31, 2014	242,392	242,104	$ 284	$ 0	201,831	41,500	(1,511)	288
Increase (Decrease) in Stockholders' Equity
Net income	15,991	16,081				16,081		(90)
Other comprehensive (income) loss, net of tax	(19,607)	(19,602)					(19,602)	(5)
Share-based payments (in shares)			21
Share-based payments	6,579	6,579			6,579
Net settlement on vesting of restricted stock units (in shares)			161
Net settlement on vesting of restricted stock units	(1,481)	(1,481)	$ 2		(1,483)
Excess tax benefit from share-based payment compensation	388	388			388
Exercise of stock options (in shares)			65
Exercise of stock options	750	750	$ 1		749
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	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
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	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
Exercise of stock options (in shares)			65
Exercise of stock options	604	604			604
Purchase of treasury stock (in shares)				(420)
Purchase of treasury stock	(9,000)	(9,000)		$ 9,000
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

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
Cash flows from operating activities
Net income	$ 9,611	$ 24,650	$ 15,991	$ 22,575
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	19,199	32,474	33,286	28,429
Deferred income taxes	(174)	240	(1,745)	(621)
Share-based compensation expense	4,559	6,514	6,579	6,261
Charges associated with the exit of foreign operations	0	0	2,516	0
Fair value adjustments to contingent consideration	262	(2,066)	(5,382)	(3,937)
Other	559	(1,052)	1,647	617
Changes in operating assets and liabilities, net of effect of acquisitions
Accounts receivable	4,123	(4,999)	3,982	(23,857)
Inventories	628	1,595	388	1,203
Prepaid expenses and other current assets	(4,173)	(1,128)	(288)	(4,059)
Other assets	(280)	(684)	(821)	36
Accounts payable	(3,667)	254	(6,571)	6,125
Accrued expenses and other liabilities	(2,301)	10,187	2,006	4,532
Income taxes payable	1,913	2,139	(1,748)	(431)
Net cash provided by operating activities	30,259	68,124	49,840	36,873
Cash flows from investing activities
Purchase of property, plant and equipment	(9,093)	(14,864)	(15,104)	(16,871)
Purchase of intangible assets	(697)	(1,315)	(866)	(708)
Acquisition of businesses, net of cash acquired	(8,262)	(1,743)	(34,677)	(21,924)
Proceeds from sale of equipment	678	1,170	996	1,498
Net cash used in investing activities	(17,374)	(16,752)	(49,651)	(38,005)
Cash flows from financing activities
Repayment of capital lease obligations	(4,490)	(7,870)	(8,653)	(8,139)
Proceeds from borrowings of long-term debt	386	2,737	2,232	0
Repayment of long-term debt	(11,919)	(17,580)	(11,457)	(8,830)
Proceeds from revolver	48,400	55,800	110,300	102,880
Repayments of revolver	(34,300)	(69,600)	(86,800)	(81,300)
Payment of contingent consideration for business acquisitions	(795)	(3,147)	(3,213)	(1,678)
Purchases of treasury stock	(9,000)	0	0	0
Taxes paid related to net share settlement of equity awards	(2,323)	(1,091)	(1,481)	(1,007)
Excess tax benefit from share-based payment compensation	568	(170)	388	340
Proceeds from the exercise of stock options	604	543	750	996
Net cash (used in) provided by financing activities	(12,869)	(40,378)	2,066	3,262
Effect of exchange rate changes on cash and cash equivalents	(2,050)	(361)	(1,720)	88
Net change in cash and cash equivalents	(2,034)	10,633	535	2,218
Cash and cash equivalents:
Beginning of period	21,188	10,555	10,020	7,802
End of period	19,154	21,188	10,555	10,020
Supplemental disclosure of cash paid
Interest	2,079	4,151	4,504	3,271
Income taxes	8,119	10,686	13,243	12,920
Noncash investing and financing
Equipment acquired through capital lease obligations	1,829	8,248	8,031	11,031
Issuance of notes payable and other debt obligations primarily related to acquisitions	$ 325	$ 0	$ 20,480	$ 336

Description of Business and Basis of Presentation	7 Months Ended
Description of Business and Basis of Presentation	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation Description of Business Mistras Group, Inc. and subsidiaries (the Company) is a leading “one source” global provider of technology-enabled asset protection solutions used to evaluate the structural integrity and reliability of critical energy, industrial and public infrastructure. The Company combines industry-leading products and technologies, expertise in mechanical integrity (MI) and non-destructive testing (NDT) 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, fossil and nuclear power, alternative and renewable energy, public infrastructure, chemicals, commercial aerospace and defense, 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 noncontrolling interests are reported in stockholders’ equity in the accompanying consolidated balance sheets. The noncontrolling interests in net income, net of tax, is classified separately in the accompanying consolidated statements of income. 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. The transition period is for the seven months ended December 31, 2016. Reference to a fiscal year means the fiscal year ended May 31, which has historically been the end of the Company's fiscal year. All significant intercompany accounts and transactions have been eliminated in consolidation. For fiscal 2016, 2015 and 2014, 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. As discussed in Note 7 - Acquisitions and Dispositions, during the lag period in fiscal 2015, the Company sold an international subsidiary, and decided to sell two additional international subsidiaries. Effective December 31, 2016, the Company's International segment is no longer consolidated on a one month lag, and such change 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.

Summary of Significant Accounting Policies	7 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Revenue Recognition Revenue is generally recognized when persuasive evidence of an arrangement exists, services have been rendered or products have been delivered, the fee is fixed or determinable, and collectability is reasonably assured. Shipping and handling costs are included in cost of revenues. Taxes collected from customers and remitted to governmental authorities are presented in the consolidated statements of income on a net basis. One customer accounted for 12% of our revenues for 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. No customer accounted for 10% or more of our revenues in fiscal 2015 and 2014. The following revenue recognition policies define the manner in which we account for specific transaction types: Services Revenue is primarily derived from providing services on a time and material basis. Service arrangements generally consist of inspection professionals working under contract for a fixed period of time or on a specific customer project. Revenue is generally recognized when the service is performed in accordance with terms of each customer arrangement, upon completion of the earnings process and when collection is reasonably assured. At the end of any reporting period, earned revenue is accrued for services that have been provided which have not yet been billed. Reimbursable costs, including those related to travel and out-of-pocket expenses, are included in revenue, and equivalent amounts of reimbursable costs are included in cost of services. Products and Systems Sales of products and systems are recorded when the sales price is fixed and determinable and the risks and rewards of ownership are transferred (generally upon shipment) and when collectability is reasonably assured. These arrangements occasionally contain multiple elements or deliverables, such as hardware, software (that is essential to the functionality of the hardware) and related services. The Company recognizes revenue for delivered elements as separate units of accounting, when the delivered elements have standalone value, uncertainties regarding customer acceptance are resolved and there are no refund or return rights for the delivered elements. The Company establishes the selling prices for each deliverable based on vendor-specific objective evidence (“VSOE”), if available, third-party evidence, if VSOE is not available, or estimated selling price (“ESP”) if neither VSOE nor third-party evidence is available. The Company establishes VSOE of selling price using the price charged for a deliverable when sold separately and, in rare instances, using the price established by management having the relevant authority. Third-party evidence of selling price is established by evaluating largely similar and interchangeable competitor products or services in standalone sales to similarly situated customers. The Company determines ESP, by considering internal factors such as margin objectives, pricing practices and controls, customer segment pricing strategies and the product life cycle. Consideration is also given to market conditions such as competitor pricing strategies and industry technology life cycles. When determining ESP, the Company applies management judgment to establish margin objectives and pricing strategies and to evaluate market conditions and product life cycles. Changes in the aforementioned factors may result in a different allocation of revenue to the deliverables in multiple element arrangements and therefore may change the pattern and timing of revenue recognition for these elements, but will not change the total revenue recognized for the arrangement. A portion of the Company’s revenue is generated from engineering and manufacturing of custom products under long-term contracts that may last from several months to several years, depending on the contract. Revenues from long-term contracts are recognized on the percentage-of-completion method of accounting. Under the percentage-of-completion method of accounting revenues are recognized as work is performed. The percentage of completion at any point in time is generally based on total costs or total labor dollars incurred to date in relation to the total estimated costs or total labor dollars estimated at completion. The percentage of completion is then applied to the total contract revenue to determine the amount of revenue to be recognized in the period. Application of the percentage-of-completion method of accounting requires the use of estimates of costs to be incurred for the performance of the contract. Contract costs include all direct materials, direct labor costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs, and all costs associated with operation of equipment. The cost estimation process is based upon the professional knowledge and experience of our engineers, project managers and financial professionals. Factors that are considered in estimating the work to be completed include the availability and productivity of labor, the nature and complexity of the work to be performed, the effect of change orders, the availability of materials, the effect of any delays in our project performance and the recoverability of any claims. Whenever revisions of estimated contract costs and 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. Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles 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 accounting policies that the Company believes require more significant estimates and assumptions include: revenue recognition (only for certain arrangements discussed above), valuations of accounts receivable, long lived assets, goodwill, and deferred tax assets and uncertain tax positions. 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. 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. One customer accounted for 11% of our accounts receivable as of December 31, 2016 and in fiscal 2016. No customer accounted for 10% or more of our accounts receivable in fiscal 2015. 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. We test 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). In connection with the transition period ended December 31, 2016, the Company tested goodwill for impairment using a two-step approach for its reporting units with a test date of December 1. Historically, the Company tested for impairment annually as of March 1, or 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. Prospectively, the Company's annual impairment test date will be October 1. 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. In this case, a second step is performed to allocate the fair value of the reporting unit to the assets and liabilities of the reporting unit as if it had just been acquired in a business combination, and as if the purchase price was equivalent to the fair value of the reporting unit. The excess of the fair value of the reporting unit over the amounts assigned to its assets and liabilities is referred to as the implied fair value of goodwill. The implied fair value of the reporting unit’s goodwill is then compared to the actual carrying value of goodwill. If the implied fair value is less than the carrying value, an impairment loss would be recorded to reduce the carrying value of goodwill to its implied fair value. 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. Significant deterioration in industry or economic trends, disruptions to our business, inability to effectively integrate acquired businesses, or other factors, may cause these fair value to decline, possibly resulting in impairment charges to goodwill in future periods. 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. 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 $1.2 million, $1.8 million, $2.2 million and $1.8 million for the transition period ended December 31, 2016 and in fiscal 2016, 2015 and 2014, 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. The carrying value of long-term debt approximates fair value due to the variable-rate structure of the debt. The fair value of the Company’s notes payable and capital lease obligations approximate their carrying amounts as those obligations bear interest at rates which management believes would currently be available to the Company for similar obligations. 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 $(0.7) million, $(0.1) million, $1.5 million and $0.1 million for the transition period ended December 31, 2016 and in fiscal 2016, 2015 and 2014, respectively. Concentrations of Credit Risk 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. Self-Insurance The Company is self-insured for certain losses relating to workers’ compensation and health benefits claims. The Company maintains third-party excess insurance coverage for all workers' compensation and health benefit claims in excess of approximately $0.3 million 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 has been 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 will become effective for us beginning 2018, which is when we plan to adopt this standard. 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. We are still in the process of evaluating the effect of adoption on our consolidated financial statements and are currently assessing our contracts with customers. We anticipate we will expand our consolidated financial statement disclosures in order to comply with ASU 2014-09. In September 2015, the FASB issued ASU No. 2015-16, Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments. This amendment will simplify the accounting for adjustments made to provisional amounts recognized in a business combination and eliminates the requirement to retrospectively account for those adjustments in previous reporting periods. This update will require on the face of the income statement or in the notes to the financial statements the amount recorded in current-period earnings that would have previously been recorded if the adjustment to the provisional amounts had been recognized as of the acquisition date. ASU 2015-16 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2015. The Company adopted this guidance during the transition period ended December 31, 2016. There was not a material impact on its consolidated financial statements and related disclosures. In November 2015, the FASB issued ASU No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. This amendment will simplify the presentation of deferred tax assets and liabilities on the balance sheet and require all deferred tax assets and liabilities to be treated as non-current. ASU 2015-17 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2016, with early adoption permitted. The Company does not expect that ASU 2015-17 will have a material impact on its consolidated financial statements and related disclosures. 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 exception of leases with a term of 12 months or less, to be recorded on the balance sheet as lease assets and lease liabilities. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2018, with early adoption permitted. The standard requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and related disclosures. In March 2016, the FASB issued ASU No. 2016-09, Stock Compensation (Topic 718). This amendment will simplify certain aspects of accounting for share-based payment transactions, which include accounting for income taxes and the related impact on the statement of cash flows, an option to account for forfeitures when they occur in addition to the existing guidance to estimate the forfeitures of awards, classification of awards as either equity or liabilities and classification on the statement of cash flows for employee taxes paid to tax authorities on shares withheld for vesting. ASU 2016-09 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2016, with early adoption permitted. Upon adoption of this standard, excess tax benefits and tax deficiencies will be recognized as a component of income tax expense, and the tax effects of exercised or vested awards will be treated as discrete items in the period in which they occur. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230). This amendment will provide 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 is evaluating the impact that ASU 2016-15 will have on its consolidated financial statements and related disclosures. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230). This amendment will clarify the presentation of restricted cash on the statement of cash flows. Amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning and ending cash balances on the statement of cash flows. ASU 2016-18 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2017, with early adoption permitted. The Company does not expect that ASU 2016-18 will have a material impact on its consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350). This amendment eliminates Step Two of the goodwill impairment test. Under the amendments in this update, entities should perform the annual goodwill impairment test by comparing the carrying value of its reporting units to their fair value. An entity should record an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. Tax deductibility of goodwill should be considered in evaluating any reporting unit's impairment loss to be taken. ASU 2017-04 is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the impact that ASU 2017-04 will have on its consolidated financial statements and related disclosures.

Earnings per Share

7 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

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 Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015		2014
Basic earnings per share
Numerator:
Net income attributable to Mistras Group, Inc.	$	9,568	$	24,654	$	16,081	$	22,518
Denominator
Weighted average common shares outstanding	28,989		28,856		28,613		28,365
Basic earnings per share	$	0.33	$	0.85	$	0.56	$	0.79

Diluted earnings per share:
Numerator:
Net income attributable to Mistras Group, Inc.	$	9,568	$	24,654	$	16,081	$	22,518
Denominator
Weighted average common shares outstanding	28,989		28,856		28,613		28,365
Dilutive effect of stock options outstanding	791		712		719		775
Dilutive effect of restricted stock units outstanding	345		323		258		184
	30,125		29,891		29,590		29,324
Diluted earnings per share	$	0.32	$	0.82	$	0.54	$	0.77

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 Transition Period ended December 31,	For the year ended May 31,
	2016	2016	2015	2014
Potential common stock attributable to stock options outstanding	—	5	6	5
Potential common stock attributable to performance awards outstanding	2	24	1	121
Total	2	29	7	126

Accounts Receivable, net

7 Months Ended

Dec. 31, 2016

Receivables [Abstract]

Accounts Receivable, net

Accounts receivable consist of the following:



	December 31,			May 31,
	2016			2016			2015
Trade accounts receivable	$	133,704		$	140,820		$	136,208
Allowance for doubtful accounts	(2,852		)	(2,907		)	(2,980		)
Accounts receivable, net	$	130,852		$	137,913		$	133,228

The Company had $16.8 million, $18.8 million and $15.0 million of unbilled revenues accrued as of December 31, 2016, May 31, 2016 and May 31, 2015, respectively. Unbilled revenues as of December 31, 2016 are expected to be billed in the first quarter of 2017.

Inventories

7 Months Ended

Dec. 31, 2016

Inventory Disclosure [Abstract]

Inventories

Inventories consist of the following:



	December 31,		May 31,
	2016		2016		2015
Raw materials	$	5,409	$	3,827	$	4,194
Work in progress	1,246		1,743		1,604
Finished goods	1,874		2,839		3,178
Services-related consumable supplies	1,488		1,509		1,865
Inventory	$	10,017	$	9,918	$	10,841

Property, Plant and Equipment, net

7 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment, net

Property, plant and equipment consist of the following:



		December 31,			May 31,
	Useful Life	2016			2016			2015
	(Years)
Land		$	1,714		$	1,735		$	1,856
Building and improvements	30-40	19,261			19,364			17,712
Office furniture and equipment	5-8	9,069			8,692			7,934
Machinery and equipment	5-7	169,928			173,053			162,762
		199,972			202,844			190,264
Accumulated depreciation and amortization		(126,823		)	(124,168		)	(111,008		)
Property, plant and equipment, net		$	73,149		$	78,676		$	79,256

Depreciation expense was approximately $14.0 million, $22.9 million, $22.2 million and $19.2 million for the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014, respectively.

Acquisitions and Dispositions

7 Months Ended

Dec. 31, 2016

Business Combinations [Abstract]

Acquisitions and Dispositions

Acquisitions

During the transition period ended December 31, 2016, the Company completed three acquisitions. The Company purchased three companies, two that provide NDT services, located in Canada and one that provides mechanical services, located in the U.S.

For the Canadian acquisitions, the Company acquired 100% of the common stock of both acquirees in exchange for aggregate consideration of $1.3 million in cash, $0.3 million of notes payable and contingent consideration estimated to be $0.4 million to be earned based upon the acquired businesses achieving specific performance metrics over their initial three years of operations from their acquisition dates. For the U.S. acquisition, the Company acquired assets of the acquiree in exchange for aggregate consideration of $7.0 million in cash and contingent consideration estimated to be $1.2 million to be earned based upon the acquired businesses achieving specific performance metrics over the initial three years of operations from its acquisition date. The Company accounted for these three transactions in accordance with the acquisition method of accounting for business combinations. The estimated total potential contingent consideration for these acquisitions ranged from zero to $2.6 million as of December 31, 2016.

During fiscal 2016, the Company completed two acquisitions. The Company purchased a U.S.-based company that provides unmanned aerial systems and NDT services and a Canadian-based company that provides engineering and NDT services. In these acquisitions, the Company acquired 100% of the common stock of each acquiree in exchange for aggregate consideration of $1.8 million in cash and contingent consideration estimated to be $1.0 million to be earned based upon the acquired business achieving specific performance metrics over various periods during the initial four years of operations from the acquisition date. The Company accounted for these transactions in accordance with the acquisition method of accounting for business combinations. The estimated total potential contingent consideration for these acquisitions ranged from zero to $0.3 million as of May 31, 2016.

During fiscal 2015, the Company completed the acquisition of four companies. One of the acquired companies is located in the U.S. and provides maintenance and inspection services primarily on offshore platforms. This acquisition expanded the service offerings within the Services segment, allowing the Company to provide services to the upstream operations of its customers. The Company also purchased a group of asset protection businesses located in Quebec, Canada and an asset inspection business in Florida to complement service offerings within the Company’s Services segment and continue its market expansion strategy. The Company’s International Segment completed an acquisition of an asset inspection business located in the United Kingdom. In these acquisitions, the Company acquired 100% of the common stock or certain assets of each acquiree in exchange for aggregate consideration of approximately $35.8 million in cash and $20.5 million in notes payable over two years. The Company accounted for such transactions in accordance with the acquisition method of accounting for business combinations. In addition to the cash consideration related to these acquisitions, the Company accrued a liability of approximately $2.3 million, which represents the estimated fair value of contingent consideration expected to be payable in the event that the acquired companies achieve specific performance metrics during various periods over the next three years of operations. The estimated total potential contingent consideration for these acquisitions ranged from zero to $3.2 million as of May 31, 2015.

Assets and liabilities of the acquired businesses were included in the consolidated balance sheets as of December 31, 2016 based on their 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 acquisitions completed during the transition period ended December 31, 2016. The results of operations of each of the acquisitions completed during the transition period ended December 31, 2016, as well as those in fiscal 2016 and 2015, are included in each respective operating segment’s results of operations from the date of acquisition. The Company’s allocation of purchase price for these acquisitions is included in the table below. The following table summarizes the estimated fair value of the assets acquired and liabilities assumed and any subsequent adjustments made during the transition period ended December 31, 2016 as well as for fiscal 2016 and 2015:



	Transition Period			2016			2015
Number of entities	3			2			4

Cash paid	$	8,295		$	1,784		$	35,755
Notes payable	325			—			20,505
Contingent consideration	1,630			991			2,255
Consideration paid	$	10,250		$	2,775		$	58,515

Current net assets	$	1,632		$	180		$	2,770
Debt and other long-term liabilities	(214		)	(546		)	(5,889		)
Property, plant and equipment	953			485			7,395
Deferred tax asset (liability)	392			(72		)	(2,467		)
Intangibles	3,367			—			10,394
Goodwill	4,120			2,728			46,312
Net assets acquired	$	10,250		$	2,775		$	58,515

The amortization period for intangible assets acquired ranges from two to twelve years. The Company recorded $4.1 million, $2.7 million and $46.3 million of goodwill in connection with its acquisitions for the transition period ended December 31, 2016, fiscal 2016 and fiscal 2015, respectively, reflecting the strategic fit and revenue and earnings growth potential of these businesses.

We are continuing our review of our fair value estimate of assets acquired and liabilities assumed for the three entities acquired in the transition period ended December 31, 2016 disclosed above. Goodwill for these three entities totaled $4.1 million and relates primarily to acquisition of the acquirees' assets, which is generally deductible for tax purposes. These measurement periods will not exceed one year from the respective acquisition dates. The goodwill recorded in fiscal 2016 and 2015 relates primarily to the acquisition of the common stock of the acquirees, which is generally not deductible for tax purposes.

Revenue included in the consolidated statement of income for the transition period ended December 31, 2016 from these acquisitions for the period subsequent to the closing of the transition period transactions was approximately $2.7 million. Aggregate income from operations included in the consolidated statement of income for the transition period ended December 31, 2016 from the acquisitions for the period subsequent to the closing of each transaction was less than $0.1 million. As these acquisitions were immaterial on an individual basis and in the aggregate, no unaudited pro forma financial information has been included in this report.

Dispositions

On May 22, 2015, the Company completed the sale of one of its Russian subsidiaries and recognized a loss of $0.4 million. On July 31, 2015, the Company completed the sale of its other subsidiary in Russia, as well as its subsidiary in Japan. For the year ended May 31, 2015, the Company recognized impairment charges of $2.1 million related to these sales. Aggregate charges associated with the exit of these three foreign operations was approximately $2.5 million and is included within selling, general and administrative expenses on the consolidated income statement for the year ended May 31, 2015. In the aggregate, the assets and liabilities of these subsidiaries represent 0.6% and 0.3% of consolidated assets and liabilities, respectively, and are included in their natural classifications on the consolidated balance sheet as of May 31, 2015.

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 transition period ended December 31, 2016 and in fiscal 2016, 2015 and 2014:



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016			2015			2014
Due diligence, professional fees and other transaction costs	$	231	$	629		$	215		$	1,280
Adjustments to fair value of contingent consideration liabilities	$	265	$	(2,082	)	$	(5,382	)	$	(3,937	)
Acquisition-related (benefit) expense, net	$	496	$	(1,453	)	$	(5,167	)	$	(2,657	)

The Company’s contingent consideration liabilities are recorded on the balance sheet in accrued expenses and other liabilities.

Goodwill

7 Months Ended

Dec. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill

The changes in the carrying amount of goodwill by segment is shown below:



	Services			International			Products		Total
Balance at May 31, 2014	$	73,767		$	43,552		$	13,197	$	130,516
Goodwill acquired during the year	41,986			1,480			—		43,466
Adjustments to preliminary purchase price allocations	3,529			(367		)	—		3,162
Foreign currency translation	(2,003		)	(8,727		)	—		(10,730		)
Balance at May 31, 2015	$	117,279		$	35,938		$	13,197	$	166,414
Goodwill acquired (disposed) during the year	2,728			(374		)	—		2,354
Adjustments to preliminary purchase price allocations	270			—			—		270
Foreign currency translation	(594		)	776			—		182
Balance at May 31, 2016	$	119,683		$	36,340		$	13,197	$	169,220
Goodwill acquired during the year	4,120			—			—		4,120
Adjustments to preliminary purchase price allocations	(19		)	—			—		(19		)
Foreign currency translation	(392		)	(2,989		)	—		(3,381		)
Balance at December 31, 2016	$	123,392		$	33,351		$	13,197	$	169,940

Historically, the Company reviewed goodwill for impairment on a reporting unit basis on March 1 of each year and whenever events or changes in circumstances indicate the carrying value of goodwill may not be recoverable. For the transition period ended December 31, 2016, the Company reviewed goodwill for impairment on a reporting unit basis as of December 1. As of December 31, 2016, the Company did not identify any changes in circumstances that would indicate the carrying value of goodwill may not be recoverable.

The Company's cumulative goodwill impairment for each of the periods ended December 31, 2016, May 31, 2016, May 31, 2015 and May 31, 2014 was $9.9 million, which is within its International segment.

Intangible Assets

7 Months Ended

Dec. 31, 2016

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

The gross carrying amount and accumulated amortization of intangible assets were as follows:



		December 31,
		2016
	Useful Life (Years)	Gross Amount		Accumulated Amortization			Net Carrying Amount
Customer relationships	5-12	$	81,559	$	(50,417	)	$	31,142
Software/Technology	3-15	18,128		(12,577		)	5,551
Covenants not to compete	2-5	11,143		(9,647		)	1,496
Other	2-5	7,266		(5,448		)	1,818
Total		$	118,096	$	(78,089	)	$	40,007



		May 31,
		2016							2015
	Useful Life (Years)	Gross Amount		Accumulated Amortization			Net Carrying Amount		Gross Amount		Accumulated Amortization			Net Carrying Amount
Customer relationships	5-12	$	81,262	$	(47,747	)	$	33,515	$	81,101	$	(41,009	)	$	40,092
Software/Technology	3-15	17,539		(11,855		)	5,684		15,738		(10,290		)	5,448
Covenants not to compete	2-5	10,791		(9,290		)	1,501		11,678		(8,605		)	3,073
Other	2-5	7,827		(5,035		)	2,792		6,910		(4,247		)	2,663
Total		$	117,419	$	(73,927	)	$	43,492	$	115,427	$	(64,151	)	$	51,276

Amortization expense for the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014 was approximately $5.2 million, $9.6 million, $11.1 million and $9.2 million, respectively, including amortization of software/technology for the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014 of $0.5 million, $1.0 million, $0.9 million and $0.9 million, respectively.

Amortization expense in each of the five years and thereafter subsequent to December 31, 2016 related to the Company’s intangible assets is expected to be as follows:



	Expected Amortization Expense

2017	$	8,230
2018	6,783
2019	5,572
2020	4,364
2021	4,040
Thereafter	11,018
Total	$	40,007

Long-Term Debt

7 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Long-Term Debt

Long-term debt consists of the following:



	December 31,			May 31,
	2016			2016			2015
Senior credit facility	$	82,776		$	68,999		$	83,062
Notes payable	320			10,111			24,632
Other	4,200			5,899			5,765
Total debt	87,296			85,009			113,459
Less: Current portion	(1,379		)	(12,553		)	(17,902		)
Long-term debt, net of current portion	$	85,917		$	72,456		$	95,557

Senior Credit Facility

On October 31, 2014, the Company entered into a Third Amendment and Modification Agreement (the “Amendment”), of its revolving line of credit, the Third Amended and Restated Credit Agreement (“Credit Agreement”), dated December 21, 2011, with its lending group. The Amendment increased the Company’s revolving line of credit from $125.0 million to $175.0 million and provides that under certain circumstances the line of credit can be increased to $225.0 million. The Company may continue to borrow up to $30.0 million in non-U.S. Dollar currencies and use up to $10.0 million of the credit limit for the issuance of letters of credit. The Amendment also extended the original maturity date of the Credit Agreement from December 20, 2016 to October 30, 2019. At December 31, 2016, the Company had borrowings of $82.8 million and letters of credit of $5.7 million were outstanding under the Credit Agreement. The Company capitalized $0.7 million of costs associated with this debt modification.

Loans under the Credit Agreement bear interest at LIBOR plus an applicable LIBOR margin ranging from 1% to 1.75%, 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 or minus certain other adjustments) for the period of four consecutive fiscal quarters immediately preceding the date of determination. The Company has the benefit of the lowest margin if its Funded Debt Leverage Ratio is equal to or less than 0.5 to 1, and the margin increases as the ratio increases, to the maximum margin if the ratio is greater than 2.0 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.

The Credit Agreement contains financial covenants requiring that the Company maintain a Funded Debt Leverage Ratio of no greater than 3.25 to 1 and an Interest Coverage Ratio of at least 3.0 to 1. Interest Coverage Ratio means the ratio, as of any date of determination, of (a) EBITDA for the 12 month period immediately preceding the date of determination, to (b) all interest, premium payments, debt discount, fees, charges and related expenses of the Company and its subsidiaries in connection with borrowed money (including capitalized interest) or in connection with the deferred purchase price of assets, in each case to the extent treated as interest in accordance with GAAP, paid during the 12 month period immediately preceding the date of determination. The 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, 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, 2016, 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 and bear interest at the prime rate for the Bank of Canada, currently 2.7% as of December 31, 2016. Interest expense is recorded in the consolidated statements of income.

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 issues of debt.

Scheduled principal payments due under all borrowing agreements in each of the five years and thereafter subsequent to December 31, 2016 are as follows:



2017	$	1,379
2018	881
2019	83,494
2020	411
2021	194
Thereafter	937
Total	$	87,296

Fair Value Measurements

7 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

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.

In accordance with the fair value hierarchy described above, the following table shows the fair value of the Company’s financial liabilities that are required to be remeasured at fair value on a recurring basis:



	December 31, 2016
	Level 1		Level 2		Level 3		Total
Liabilities:
Contingent consideration	$	—	$	—	$	3,094	$	3,094
Total Liabilities	$	—	$	—	$	3,094	$	3,094



	May 31, 2016
	Level 1		Level 2		Level 3		Total
Liabilities:
Contingent consideration	$	—	$	—	$	2,075	$	2,075
Total Liabilities	$	—	$	—	$	2,075	$	2,075



	May 31, 2015
	Level 1		Level 2		Level 3		Total
Liabilities:
Contingent consideration	$	—	$	—	$	6,411	$	6,411
Total Liabilities	$	—	$	—	$	6,411	$	6,411

The fair value of contingent consideration liabilities that was classified as Level 3 in the table above 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 acquisition agreements.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Share-Based Compensation

7 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

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 the 2007 Plan and 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 all of the shares were available for future grants as of December 31, 2016. As of December 31, 2016, there was an aggregate of approximately 2,167,000 stock options outstanding and approximately 858,000 unvested restricted stock units outstanding under the 2009 Plan and the 2007 Plan.

Stock Options

For the transition period ended December 31, 2016, the Company did not have any share-based compensation expense related to stock option awards. For the fiscal years ended May 31, 2016 and 2015, the Company recognized share-based compensation expense related to stock option awards of less than $0.1 million, respectively, and $0.7 million for the fiscal year ended May 31, 2014. No stock options were granted during the transition period ended December 31, 2016 or the years ended May 31, 2016, 2015 and 2014. As of December 31, 2016, no unrecognized compensation costs remained related to stock option awards. Cash proceeds from, and the intrinsic value of stock options exercised during the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014 were as follows:



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015		2014
Cash proceeds from options exercised	$	604	$	543	$	750	$	996
Aggregate intrinsic value of options exercised	993		658		563		1,247

A summary of the stock option activity, weighted average exercise prices, options outstanding and exercisable as of December 31, 2016 is as follows (in thousands, except per share amounts):



	For the Transition Period ended December 31,				For the year ended May 31,
	2016				2016				2015				2014
	Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price
Outstanding at beginning of year:	2,232		$	13.21	2,287		$	13.13	2,352		$	13.09	2,464		$	12.93
Granted	—		$	—	—		$	—	—		$	—	—		$	—
Exercised	(65	)	$	9.27	(55	)	$	9.87	(65	)	$	11.54	(103	)	$	9.67
Expired or forfeited	—		$	—	—		$	—	—		$	—	(9	)	$	10.03
Outstanding at end of year:	2,167		$	13.33	2,232		$	13.21	2,287		$	13.13	2,352		$	13.09



			For the Transition Period ended December 31, 2016
			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
$6.15-$11.54	72		1.5	$	8.93	72		$	8.93
$13.46-$22.35	2,095		2.7	$	13.48	2,095		$	13.48
	2,167					2,167

Aggregate Intrinsic Value	$	26,760				$	26,760

Restricted Stock Unit Awards

The Company recognized approximately $2.6 million of share-based compensation for the transition period ended December 31, 2016, $4.4 million of share-based compensation in fiscal 2016, $4.7 million of share-based compensation in fiscal 2015 and $4.0 million of share-based compensation expense in fiscal 2014 related to restricted stock unit awards. As of December 31, 2016, there were approximately $9.4 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 2.7 years. Approximately 207,000 restricted stock units vested in the transition period ended December 31, 2016, of which the fair value of these units was $5.1 million. Approximately 223,000 restricted stock units vested in fiscal 2016, 232,000 restricted stock units vested in fiscal 2015 and 178,000 restricted stock units vested in fiscal 2014. The fair value of these units was $3.5 million, $5.2 million and $3.3 million, respectively. Upon vesting, restricted stock units are generally net share-settled to cover the required minimum withholding tax and the remaining amount is converted into an equivalent number of shares of common stock.

During the transition period ended December 31, 2016, the Company granted approximately 10,000 shares of fully-vested common stock to its five non-employee directors, in connection with its non-employee director compensation plan, which shares had a grant date fair value of approximately $0.3 million. During the years ended May 31, 2016, 2015 and 2014, the Company granted approximately 28,000, 21,000 and 19,000 shares, respectively, of fully-vested common stock to its five non-employee directors, in connection with its non-employee director compensation plan. These shares had a grant date fair value of approximately $0.5 million, $0.4 million and $0.4 million, respectively, which is included in the share-based compensation expense recorded during the years ended May 31, 2016, 2015 and 2014.



	For the transition period ended December 31,				For the year ended May 31,
	2016				2016				2015				2014
	Units		Weighted Average Grant-Date Fair Value		Units		Weighted Average Grant-Date Fair Value		Units		Weighted Average Grant-Date Fair Value		Units		Weighted Average Grant-Date Fair Value
Outstanding at beginning of period:	575		$	18.85	564		$	20.47	628		$	19.37	555		$	18.77
Granted	219		$	24.48	264		$	16.73	192		$	21.87	295		$	19.51
Released	(207	)	$	19.40	(223	)	$	20.40	(232	)	$	18.17	(178	)	$	17.70
Forfeited	(18	)	$	19.55	(30	)	$	19.26	(24	)	$	20.57	(44	)	$	19.67
Outstanding at end of period:	569		$	20.81	575		$	18.85	564		$	20.47	628		$	19.37

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 Performance Restricted Stock Unit activity is presented below:



	For the Transition Period ended December 31, 2016
	Units		Weighted Average Grant-Date Fair Value
Outstanding at beginning of period:	328		$	17.02
Granted	105		$	24.90
Performance condition adjustments, net	(54	)	$	24.49
Released	(89	)	$	24.50
Forfeited	—		$	—
Outstanding at end of period:	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.

Compensation expense related to all PRSUs described above was $1.7 million, $1.6 million, $1.5 million and $1.2 million for the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014. At December 31, 2016, there was $2.8 million of total unrecognized compensation costs related to approximately 290,000 nonvested performance restricted stock units. These costs are expected to be recognized over a weighted-average period of approximately 2.0 years.

For the transition period ended December 31, 2016 and the fiscal years ended May 31, 2016, 2015 and 2014, the income tax benefit recognized on all share based compensation arrangements referenced above was approximately $1.6 million, $2.2 million, $2.3 million and $2.3 million, respectively.

Income Taxes

7 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Income Taxes

Income before provision for income taxes is as follows:



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015			2014
Income (loss) before provision for income taxes from:
U.S. operations	$	5,116	$	27,772	$	26,893		$	25,433
Foreign operations	10,365		10,643		(1,162		)	9,670
Earnings before income taxes	$	15,481	$	38,415	$	25,731		$	35,103

The provision for income taxes consists of the following:



	For the Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015			2014
Current
Federal	$	1,990		$	9,156		$	8,489		$	8,836
States and local	483			1,537			1,177			1,689
Foreign	3,569			3,672			1,493			2,484
Reserve for uncertain tax positions	(39		)	(529		)	(48		)	59
Total current	6,003			13,836			11,111			13,068
Deferred
Federal	6			82			(145		)	(53		)
States and local	(28		)	(51		)	(126		)	395
Foreign	(514		)	(557		)	(2,416		)	(967		)
Total deferred	(536		)	(526		)	(2,687		)	(625		)
Net change in valuation allowance	403			455			1,316			85
Net deferred	(133		)	(71		)	(1,371		)	(540		)
Provision for income taxes	$	5,870		$	13,765		$	9,740		$	12,528

The provision for income taxes differs from the amount computed by applying the statutory federal tax rate to income tax as follows:



	For the Transition period ended December 31,
	2016
Federal tax at statutory rate	$	5,418		35.0	%
State taxes, net of federal benefit	296			1.9	%
Foreign tax	(573		)	(3.7	)%
Contingent consideration	(4		)	—	%
Permanent differences	373			2.4	%
Other	(43		)	(0.3	)%
Change in valuation allowance	403			2.6	%
Total provision for income taxes	$	5,870		37.9	%



	For the year ended May 31,
	2016					2015					2014
Federal tax at statutory rate	$	13,445		35.0	%	$	9,006		35.0	%	$	12,286		35.0	%
State taxes, net of federal benefit	966			2.5	%	683			2.7	%	1,355			3.9	%
Foreign tax	(610		)	(1.6	)%	(517		)	(2.0	)%	(1,868		)	(5.3	)%
Contingent consideration	(425		)	(1.1	)%	(914		)	(3.6	)%	24			0.1	%
Permanent differences	245			0.6	%	196			0.8	%	531			1.5	%
Other	(311		)	(0.8	)%	(30		)	(0.1	)%	115			0.3	%
Change in valuation allowance	455			1.2	%	1,316			5.1	%	85			0.2	%
Total provision for income taxes	$	13,765		35.8	%	$	9,740		37.9	%	$	12,528		35.7	%

Deferred income tax attributes resulting from differences between financial accounting amounts and income tax basis of assets and liabilities are as follows:



	December 31,			May 31,
	2016			2016			2015
Deferred income tax assets
Allowance for doubtful accounts	$	969		$	940		$	1,036
Inventory	236			518			796
Intangible assets	2,529			1,641			1,254
Accrued expenses	5,157			4,668			3,455
Net operating loss carryforward	4,094			4,036			4,738
Capital lease obligations	1,140			1,167			379
Capital losses	719			719			—
Deferred share-based compensation	5,802			6,477			6,241
Other	285			440			370
Deferred income tax assets	20,931			20,606			18,269
Valuation allowance	(3,896		)	(3,397		)	(3,238		)
Net deferred income tax assets	17,035			17,209			15,031
Deferred income tax liabilities
Property and equipment	(8,655		)	(9,785		)	(8,214		)
Goodwill	(13,586		)	(12,535		)	(10,728		)
Intangible assets	(5,051		)	(5,989		)	(6,677		)
Other	(11		)	(12		)	(44		)
Deferred income tax liabilities	(27,303		)	(28,321		)	(25,663		)
Net deferred income taxes	$	(10,268	)	$	(11,112	)	$	(10,632	)

As of December 31, 2016, 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 2030 to 2033. In addition, as of December 31, 2016, the Company had state and foreign NOLs of $15.1 million and $12.2 million, respectively. The state NOLs expire at various times from 2019 to 2036. Approximately $1.4 million of the foreign NOLs expire at various times from 2022 to 2036, 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, 2016, the Company has a valuation allowance of approximately $3.9 million primarily against certain state and foreign NOLs and the capital losses generated by the disposals of certain foreign subsidiaries. For the transition period ended December 31, 2016, the valuation allowance increased $0.5 million, primarily attributable to tax losses generated by foreign subsidiaries. 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 Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015
Balance at beginning of period	$	303		$	763		$	1,016
Additions for tax positions related to the current fiscal period	8			29			30
Additions for tax positions related to prior years	—			52			—
Decreases for tax positions related to prior years	(11		)	(23		)	(1		)
Impact of foreign exchange fluctuation	—			(91		)	(112		)
Settlements	—			(29		)	(50		)
Reductions related to the expiration of statutes of limitations	(33		)	(398		)	(120		)
Balance at end of period	$	267		$	303		$	763

The Company has recorded the unrecognized tax benefits in other long-term liabilities in the consolidated balance sheets. As of December 31, 2016, May 31, 2016 and May 31, 2015, there were approximately $0.3 million, $0.4 million and $1.1 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 transition period ended December 31, 2016 and the fiscal years ended May 31, 2016 and 2015. The Company anticipates a decrease to its unrecognized tax benefits of approximately $0.1 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, 2014 and generally is no longer subject to state, local or foreign income tax examinations by tax authorities for years ending before May 31, 2013.

The Company has not recognized U.S. tax expense on its undistributed international earnings or losses of its foreign subsidiaries since it intends to indefinitely reinvest the earnings outside the United States. Net income (loss) of foreign subsidiaries was $6.9 million, $7.5 million and $(0.8) million for the transition period ended December 31, 2016, fiscal 2016 and 2015, respectively. We have recognized no deferred tax liability for the remittance of such earnings to the U.S. since it is our intention to utilize those earnings in the foreign operations. Determination of the amount of any unrecognized deferred income tax liability on this temporary difference is not practicable because of the complexities of the hypothetical calculation.

Employee Benefit Plans	7 Months Ended
Employee Benefit Plans	Dec. 31, 2016
Compensation and Retirement Disclosure [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 $1.9 million, $3.3 million, $2.8 million and $2.5 million for the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014, respectively. The Company participates with other employers in contributing to a union plan, which covers certain U.S. based union employees. The plan is not administered by the Company and contributions are determined in accordance with provisions of a collective bargaining agreement. The Company’s contributions to the plan were $0.1 million, $0.2 million, $0.2 million and $0.1 million for the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014. The Company has benefit plans covering certain employees in selected foreign countries. Amounts charged to expense under these plans were not significant in any year.

Related Party Transactions	7 Months Ended
Related Party Transactions	Dec. 31, 2016
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions On August 17, 2016, the Company entered into an agreement with its Chairman and CEO, 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 transition period ended December 31, 2016 were approximately $0.5 million. See Note 18 — Commitments and Contingencies 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 transition period ended December 31, 2016 were approximately $0.1 million. 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 transition period ended December 31, 2016 were approximately $0.1 million.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Obligations under Capital Leases

7 Months Ended

Dec. 31, 2016

Leases [Abstract]

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 $76 thousand, including effective interest rates that range from approximately 1% to 8% expiring through May 2022. The net book value of assets under capital lease obligations was $17.6 million, $19.8 million and $19.9 million at December 31, 2016, May 31, 2016 and May 31, 2015, respectively.

Scheduled future minimum lease payments subsequent to December 31, 2016 are as follows:



2017	$	7,033
2018	5,312
2019	3,008
2020	1,191
2021	556
Thereafter	88
Total minimum lease payments	17,188
Less: amount representing interest	(1,018		)
Present value of minimum lease payments	16,170
Less: current portion of obligations under capital leases	(6,488		)
Obligations under capital leases, net of current portion	$	9,682

Commitments and Contingencies

7 Months Ended

Dec. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Operating Leases

The Company is party to various noncancelable 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, 2016 are as follows:



2017	$	9,390
2018	8,068
2019	6,115
2020	4,566
2021	3,603
Thereafter	11,609
Total	$	43,351

Total rent expense was $6.6 million, $11.2 million, $10.6 million and $9.5 million for the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014, 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 was a defendant in a consolidated purported class and collective action, Edgar Viceral and David Kruger v Mistras Group, et al, pending in the U.S. District Court for the Northern District of California. This matter results from the consolidation of two cases originally filed in California state court in April 2015. The consolidated case alleged violations of California statutes, primarily the California Labor Code, and sought to proceed as a collective action under the U.S. Fair Labor Standards Act. The case is predicated on claims for allegedly missed rest and meal periods, inaccurate wage statements, and failure to pay all wages due, as well as related unfair business practices, and is requesting payment of all damages, including unpaid wages, and various fines and penalties available under California and Federal law.

The parties have reached a settlement of the case, whereby the Company agreed to pay $6 million to resolve the allegations and avoid further distraction that would result if the litigation continued. The settlement received preliminary approval by the court in October 2016. A hearing on final approval of the settlement was held on February 2, 2017 and a final ruling was rendered on February 17, 2017. The Company recorded a pre-tax charge of $6.3 million in the fourth quarter of fiscal 2016 for the settlement and payment of payroll taxes and other costs related to the settlement, which was paid in February 2017. The settlement covered claims dating back to April 2011 in some cases and involved approximately 4,900 current and former employees.

The Company is a defendant in the lawsuit AGL Services Company v. Mistras Group, Inc., pending in U.S. District Court for

the Northern District of Georgia, filed November 2016. The case involves radiography work performed by the Company in

fiscal 2013 on the construction of a pipeline project in the U.S. The owner of the pipeline project contends that certain of the

radiography images the Company’s technicians prepared regarding the project did not meet the code quality interpretation

standards required by the American Petroleum Institute. The project owner is claiming damages as a result of the alleged

quality defects of the Company’s radiography images. The complaint alleges damages of approximately $6 million. The Company is currently unable to determine the likely outcome or reasonably estimate the amount or range of potential liability related to this matter, and accordingly, has not established any reserves for this matter.

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 judgment is being appealed, but the Company recorded a reserve for the full amount of the judgment in the fourth quarter of fiscal 2016.

The Company is 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 alleges Mistras delivered, in fiscal 2014, a defective Ultrasonic inspection system and is alleging damages of approximately $2.3 million, the amount it paid for the system. The Company is vigorously defending the case and has not

established any reserves for the matter at this time.

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. 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.

Acquisition-related contingencies

The Company is liable for contingent consideration in connection with certain of its acquisitions. As of December 31, 2016, total potential acquisition-related contingent consideration ranged from zero to $15.2 million and would be payable upon the achievement of specific performance metrics by certain of the acquired companies over the next 2.8 years of operations. See Note 7 - Acquisitions to these consolidated financial statements for further information with respect to the Company’s acquisitions completed during the transition period ended December 31, 2016 and in fiscal 2015 and 2016.

Segment Disclosure

7 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

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, 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 Company’s other segments to global markets, in 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 2 — Summary of Significant Accounting Policies. 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 Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015			2014
Revenues
Services	$	293,218		$	553,279		$	540,224		$	443,229
International	104,013			143,025			146,953			161,395
Products and Systems	14,541			30,293			31,255			33,544
Corporate and eliminations	(7,611		)	(7,416		)	(7,180		)	(14,721		)
	$	404,161		$	719,181		$	711,252		$	623,447



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015		2014
Gross profit
Services	$	75,784	$	145,262	$	135,201	$	114,182
International	34,210		43,613		34,572		44,893
Products and Systems	6,920		14,022		14,314		14,495
Corporate and eliminations	90		111		646		(627		)
	$	117,004	$	203,008	$	184,733	$	172,943



	For the Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015			2014
Income from operations
Services	$	22,411		$	52,552		$	49,142		$	43,221
International	10,597			9,293			(575		)	10,238
Products and Systems	(254		)	2,688			2,461			2,552
Corporate and eliminations	(15,221		)	(21,356		)	(20,675		)	(17,716		)
	$	17,533		$	43,177		$	30,353		$	38,295



	For the Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015		2014
Depreciation and amortization
Services	$	12,765		$	22,725		$	22,268	$	17,794
International	5,306			7,774			8,451		8,065
Products and Systems	1,372			2,323			2,426		2,373
Corporate and eliminations	(244		)	(348		)	141		197
	$	19,199		$	32,474		$	33,286	$	28,429



	December 31,		May 31,
	2016		2016		2015
Intangible assets, net
Services	$	19,550	$	19,022	$	24,598
International	14,139		17,703		19,482
Products and Systems	5,482		6,054		7,004
Corporate and eliminations	836		713		192
	$	40,007	$	43,492	$	51,276



	December 31,		May 31,
	2016		2016		2015
Total assets
Services	$	291,539	$	301,678	$	301,031
International	130,427		132,643		126,643
Products and Systems	28,964		31,596		35,464
Corporate and eliminations	18,497		16,758		8,589
	$	469,427	$	482,675	$	471,727

Revenue and long-lived assets by geographic area was as follows:



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015		2014
Revenue
United States	$	256,926	$	519,361	$	491,818	$	403,001
Other Americas	41,777		67,809		68,628		55,120
Europe	91,847		118,566		137,071		143,931
Asia-Pacific	13,611		13,445		13,735		21,395
	$	404,161	$	719,181	$	711,252	$	623,447



	December 31,		May 31,
	2016		2016		2015
Long-lived assets
United States	$	186,960	$	186,543	$	190,997
Other Americas	29,065		29,743		31,558
Europe	67,072		75,102		73,744
Asia-Pacific	—		—		647
	$	283,097	$	291,388	$	296,946

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8538-108599

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 29
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8864-108599

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8924-108599

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8906-108599

+ Details

Repurchase of Common Stock	7 Months Ended
Repurchase of Common Stock	Dec. 31, 2016
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 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 will 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. In addition, during this same transition period, the Company repurchased approximately 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. All such repurchased shares are classified as Treasury Stock on the consolidated balance sheet. As of December 31, 2016, approximately $41.0 million remained available to repurchase shares under the stock repurchase plan.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

Seven Months Ended December 31, 2015 Comparative Data (Unaudited)

7 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Seven Months Ended December 31, 2015 Comparative Data (Unaudited)

SEVEN MONTHS ENDED DECEMBER 31, 2015 COMPARATIVE DATA (Unaudited)

The condensed consolidated statement of income for the seven months ended December 31, 2015 is as follows: (In thousands, except per share data)



	Seven Months Ended December 31, 2015
	(unaudited)
Revenues	$	427,913
Cost of revenues	292,718
Depreciation	12,005
Gross profit	123,190
Selling, general and administrative expenses	81,117
Research and engineering	1,431
Depreciation and amortization	6,503
Acquisition-related benefit, net	(959		)
Income from operations	35,098
Interest expense, net	3,672
Income before provision for income taxes	31,426
Provision for income taxes	11,627
Net Income	19,799
Less: Net (loss) attributable to non-controlling interests	(15		)
Net income available to Mistras Group, Inc. shareholders	$	19,814
Net income per share: Basic	$	0.69
Net income per share: Diluted	$	0.67
Weighted average shares outstanding:
Basic	28,810
Diluted	29,676

Selected Quarterly Financial Information (unaudited)

7 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Information (unaudited)

The following is a summary of the quarterly results of operations for November 30, 2016, August 31, 2016 and the fiscal years ended May 31, 2016 and 2015:



Fiscal quarter ended	November 30, 2016		August 31, 2016		May 31, 2016		February 29, 2016		November 30, 2015		August 31, 2015		May 31, 2015		February 28, 2015		November 30, 2014		August 31, 2014
Revenues	$	176,642	$	168,443	$	184,187	$	160,355	$	194,786	$	179,853	$	174,686	$	163,100	$	206,893	$	166,573
Gross Profit	52,076		50,056		52,000		42,809		56,925		51,274		44,966		38,734		59,039		41,994
Income from operations	12,508		11,155		4,918		5,758		19,569		12,932		4,627		3,870		18,192		3,664
Net income attributable to Mistras Group, Inc.	$	7,270	$	6,596	$	2,764	$	3,593	$	11,425	$	6,872	$	2,171	$	1,817	$	10,427	$	1,666
Earnings per common share:
Basic	$	0.25	$	0.23	$	0.10	$	0.12	$	0.40	$	0.24	$	0.08	$	0.06	$	0.36	$	0.06
Diluted	$	0.24	$	0.22	$	0.09	$	0.12	$	0.39	$	0.23	$	0.07	$	0.06	$	0.35	$	0.06

Subsequent Events	7 Months Ended
Subsequent Events	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Subsequent to December 31, 2016, the Company completed an acquisition of a business that provides NDT, chemical and special processing services, located in the U.S, for $4.5 million in cash upon closing and $1.5 million of deferred purchase price. In addition to the cash consideration, the acquisition provides for possible contingent consideration up to $2.0 million to be earned based upon the achievement of specific performance metrics over the next three years of operation. The Company is in the process of completing the preliminary purchase price allocation. The acquisition was not significant and no pro forma information has been included in this transition report on Form 10-K.

Summary of Significant Accounting Policies (Policies)	7 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2016
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 noncontrolling interests are reported in stockholders’ equity in the accompanying consolidated balance sheets. The noncontrolling interests in net income, net of tax, is classified separately in the accompanying consolidated statements of income. 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. The transition period is for the seven months ended December 31, 2016. Reference to a fiscal year means the fiscal year ended May 31, which has historically been the end of the Company's fiscal year. All significant intercompany accounts and transactions have been eliminated in consolidation. For fiscal 2016, 2015 and 2014, 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. As discussed in Note 7 - Acquisitions and Dispositions, during the lag period in fiscal 2015, the Company sold an international subsidiary, and decided to sell two additional international subsidiaries. Effective December 31, 2016, the Company's International segment is no longer consolidated on a one month lag, and such change 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.
Revenue Recognition	Revenue Recognition Revenue is generally recognized when persuasive evidence of an arrangement exists, services have been rendered or products have been delivered, the fee is fixed or determinable, and collectability is reasonably assured. Shipping and handling costs are included in cost of revenues. Taxes collected from customers and remitted to governmental authorities are presented in the consolidated statements of income on a net basis. One customer accounted for 12% of our revenues for 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. No customer accounted for 10% or more of our revenues in fiscal 2015 and 2014. The following revenue recognition policies define the manner in which we account for specific transaction types: Services Revenue is primarily derived from providing services on a time and material basis. Service arrangements generally consist of inspection professionals working under contract for a fixed period of time or on a specific customer project. Revenue is generally recognized when the service is performed in accordance with terms of each customer arrangement, upon completion of the earnings process and when collection is reasonably assured. At the end of any reporting period, earned revenue is accrued for services that have been provided which have not yet been billed. Reimbursable costs, including those related to travel and out-of-pocket expenses, are included in revenue, and equivalent amounts of reimbursable costs are included in cost of services. Products and Systems Sales of products and systems are recorded when the sales price is fixed and determinable and the risks and rewards of ownership are transferred (generally upon shipment) and when collectability is reasonably assured. These arrangements occasionally contain multiple elements or deliverables, such as hardware, software (that is essential to the functionality of the hardware) and related services. The Company recognizes revenue for delivered elements as separate units of accounting, when the delivered elements have standalone value, uncertainties regarding customer acceptance are resolved and there are no refund or return rights for the delivered elements. The Company establishes the selling prices for each deliverable based on vendor-specific objective evidence (“VSOE”), if available, third-party evidence, if VSOE is not available, or estimated selling price (“ESP”) if neither VSOE nor third-party evidence is available. The Company establishes VSOE of selling price using the price charged for a deliverable when sold separately and, in rare instances, using the price established by management having the relevant authority. Third-party evidence of selling price is established by evaluating largely similar and interchangeable competitor products or services in standalone sales to similarly situated customers. The Company determines ESP, by considering internal factors such as margin objectives, pricing practices and controls, customer segment pricing strategies and the product life cycle. Consideration is also given to market conditions such as competitor pricing strategies and industry technology life cycles. When determining ESP, the Company applies management judgment to establish margin objectives and pricing strategies and to evaluate market conditions and product life cycles. Changes in the aforementioned factors may result in a different allocation of revenue to the deliverables in multiple element arrangements and therefore may change the pattern and timing of revenue recognition for these elements, but will not change the total revenue recognized for the arrangement. A portion of the Company’s revenue is generated from engineering and manufacturing of custom products under long-term contracts that may last from several months to several years, depending on the contract. Revenues from long-term contracts are recognized on the percentage-of-completion method of accounting. Under the percentage-of-completion method of accounting revenues are recognized as work is performed. The percentage of completion at any point in time is generally based on total costs or total labor dollars incurred to date in relation to the total estimated costs or total labor dollars estimated at completion. The percentage of completion is then applied to the total contract revenue to determine the amount of revenue to be recognized in the period. Application of the percentage-of-completion method of accounting requires the use of estimates of costs to be incurred for the performance of the contract. Contract costs include all direct materials, direct labor costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs, and all costs associated with operation of equipment. The cost estimation process is based upon the professional knowledge and experience of our engineers, project managers and financial professionals. Factors that are considered in estimating the work to be completed include the availability and productivity of labor, the nature and complexity of the work to be performed, the effect of change orders, the availability of materials, the effect of any delays in our project performance and the recoverability of any claims. Whenever revisions of estimated contract costs and 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.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with generally accepted accounting principles 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 accounting policies that the Company believes require more significant estimates and assumptions include: revenue recognition (only for certain arrangements discussed above), valuations of accounts receivable, long lived assets, goodwill, and deferred tax assets and uncertain tax positions. 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. 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.
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. We test 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). In connection with the transition period ended December 31, 2016, the Company tested goodwill for impairment using a two-step approach for its reporting units with a test date of December 1. Historically, the Company tested for impairment annually as of March 1, or 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. Prospectively, the Company's annual impairment test date will be October 1. 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. In this case, a second step is performed to allocate the fair value of the reporting unit to the assets and liabilities of the reporting unit as if it had just been acquired in a business combination, and as if the purchase price was equivalent to the fair value of the reporting unit. The excess of the fair value of the reporting unit over the amounts assigned to its assets and liabilities is referred to as the implied fair value of goodwill. The implied fair value of the reporting unit’s goodwill is then compared to the actual carrying value of goodwill. If the implied fair value is less than the carrying value, an impairment loss would be recorded to reduce the carrying value of goodwill to its implied fair value. 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. Significant deterioration in industry or economic trends, disruptions to our business, inability to effectively integrate acquired businesses, or other factors, may cause these fair value to decline, possibly resulting in impairment charges to goodwill in future periods.
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.
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. The carrying value of long-term debt approximates fair value due to the variable-rate structure of the debt. The fair value of the Company’s notes payable and capital lease obligations approximate their carrying amounts as those obligations bear interest at rates which management believes would currently be available to the Company for similar obligations.
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.
Concentrations of Credit Risk	Concentrations of Credit Risk 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.
Self-Insurance	Self-Insurance The Company is self-insured for certain losses relating to workers’ compensation and health benefits claims. The Company maintains third-party excess insurance coverage for all workers' compensation and health benefit claims in excess of approximately $0.3 million 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 has been 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 will become effective for us beginning 2018, which is when we plan to adopt this standard. 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. We are still in the process of evaluating the effect of adoption on our consolidated financial statements and are currently assessing our contracts with customers. We anticipate we will expand our consolidated financial statement disclosures in order to comply with ASU 2014-09. In September 2015, the FASB issued ASU No. 2015-16, Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments. This amendment will simplify the accounting for adjustments made to provisional amounts recognized in a business combination and eliminates the requirement to retrospectively account for those adjustments in previous reporting periods. This update will require on the face of the income statement or in the notes to the financial statements the amount recorded in current-period earnings that would have previously been recorded if the adjustment to the provisional amounts had been recognized as of the acquisition date. ASU 2015-16 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2015. The Company adopted this guidance during the transition period ended December 31, 2016. There was not a material impact on its consolidated financial statements and related disclosures. In November 2015, the FASB issued ASU No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. This amendment will simplify the presentation of deferred tax assets and liabilities on the balance sheet and require all deferred tax assets and liabilities to be treated as non-current. ASU 2015-17 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2016, with early adoption permitted. The Company does not expect that ASU 2015-17 will have a material impact on its consolidated financial statements and related disclosures. 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 exception of leases with a term of 12 months or less, to be recorded on the balance sheet as lease assets and lease liabilities. ASU 2016-02 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2018, with early adoption permitted. The standard requires lessees and lessors to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and related disclosures. In March 2016, the FASB issued ASU No. 2016-09, Stock Compensation (Topic 718). This amendment will simplify certain aspects of accounting for share-based payment transactions, which include accounting for income taxes and the related impact on the statement of cash flows, an option to account for forfeitures when they occur in addition to the existing guidance to estimate the forfeitures of awards, classification of awards as either equity or liabilities and classification on the statement of cash flows for employee taxes paid to tax authorities on shares withheld for vesting. ASU 2016-09 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2016, with early adoption permitted. Upon adoption of this standard, excess tax benefits and tax deficiencies will be recognized as a component of income tax expense, and the tax effects of exercised or vested awards will be treated as discrete items in the period in which they occur. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230). This amendment will provide 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 is evaluating the impact that ASU 2016-15 will have on its consolidated financial statements and related disclosures. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230). This amendment will clarify the presentation of restricted cash on the statement of cash flows. Amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning and ending cash balances on the statement of cash flows. ASU 2016-18 is effective for fiscal years, and interim periods within those fiscal years beginning after December 15, 2017, with early adoption permitted. The Company does not expect that ASU 2016-18 will have a material impact on its consolidated financial statements and related disclosures. In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350). This amendment eliminates Step Two of the goodwill impairment test. Under the amendments in this update, entities should perform the annual goodwill impairment test by comparing the carrying value of its reporting units to their fair value. An entity should record an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. Tax deductibility of goodwill should be considered in evaluating any reporting unit's impairment loss to be taken. ASU 2017-04 is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the impact that ASU 2017-04 will have on its consolidated financial statements and related disclosures.
Fair Value Measurement	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.

Earnings per Share (Tables)

7 Months Ended

Dec. 31, 2016

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 Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015		2014
Basic earnings per share
Numerator:
Net income attributable to Mistras Group, Inc.	$	9,568	$	24,654	$	16,081	$	22,518
Denominator
Weighted average common shares outstanding	28,989		28,856		28,613		28,365
Basic earnings per share	$	0.33	$	0.85	$	0.56	$	0.79

Diluted earnings per share:
Numerator:
Net income attributable to Mistras Group, Inc.	$	9,568	$	24,654	$	16,081	$	22,518
Denominator
Weighted average common shares outstanding	28,989		28,856		28,613		28,365
Dilutive effect of stock options outstanding	791		712		719		775
Dilutive effect of restricted stock units outstanding	345		323		258		184
	30,125		29,891		29,590		29,324
Diluted earnings per share	$	0.32	$	0.82	$	0.54	$	0.77

Schedule of potential common shares that were 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 Transition Period ended December 31,	For the year ended May 31,
	2016	2016	2015	2014
Potential common stock attributable to stock options outstanding	—	5	6	5
Potential common stock attributable to performance awards outstanding	2	24	1	121
Total	2	29	7	126

Property, Plant and Equipment, net (Tables)

7 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Abstract]

Schedule of Property, plant and equipment

Property, plant and equipment consist of the following:



		December 31,			May 31,
	Useful Life	2016			2016			2015
	(Years)
Land		$	1,714		$	1,735		$	1,856
Building and improvements	30-40	19,261			19,364			17,712
Office furniture and equipment	5-8	9,069			8,692			7,934
Machinery and equipment	5-7	169,928			173,053			162,762
		199,972			202,844			190,264
Accumulated depreciation and amortization		(126,823		)	(124,168		)	(111,008		)
Property, plant and equipment, net		$	73,149		$	78,676		$	79,256

Acquisitions and Dispositions (Tables)

7 Months Ended

Dec. 31, 2016

Business Combinations [Abstract]

Summary 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 and any subsequent adjustments made during the transition period ended December 31, 2016 as well as for fiscal 2016 and 2015:



	Transition Period			2016			2015
Number of entities	3			2			4

Cash paid	$	8,295		$	1,784		$	35,755
Notes payable	325			—			20,505
Contingent consideration	1,630			991			2,255
Consideration paid	$	10,250		$	2,775		$	58,515

Current net assets	$	1,632		$	180		$	2,770
Debt and other long-term liabilities	(214		)	(546		)	(5,889		)
Property, plant and equipment	953			485			7,395
Deferred tax asset (liability)	392			(72		)	(2,467		)
Intangibles	3,367			—			10,394
Goodwill	4,120			2,728			46,312
Net assets acquired	$	10,250		$	2,775		$	58,515

Schedule of acquisition-related expense, net



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016			2015			2014
Due diligence, professional fees and other transaction costs	$	231	$	629		$	215		$	1,280
Adjustments to fair value of contingent consideration liabilities	$	265	$	(2,082	)	$	(5,382	)	$	(3,937	)
Acquisition-related (benefit) expense, net	$	496	$	(1,453	)	$	(5,167	)	$	(2,657	)

Goodwill (Tables)

7 Months Ended

Dec. 31, 2016

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		Total
Balance at May 31, 2014	$	73,767		$	43,552		$	13,197	$	130,516
Goodwill acquired during the year	41,986			1,480			—		43,466
Adjustments to preliminary purchase price allocations	3,529			(367		)	—		3,162
Foreign currency translation	(2,003		)	(8,727		)	—		(10,730		)
Balance at May 31, 2015	$	117,279		$	35,938		$	13,197	$	166,414
Goodwill acquired (disposed) during the year	2,728			(374		)	—		2,354
Adjustments to preliminary purchase price allocations	270			—			—		270
Foreign currency translation	(594		)	776			—		182
Balance at May 31, 2016	$	119,683		$	36,340		$	13,197	$	169,220
Goodwill acquired during the year	4,120			—			—		4,120
Adjustments to preliminary purchase price allocations	(19		)	—			—		(19		)
Foreign currency translation	(392		)	(2,989		)	—		(3,381		)
Balance at December 31, 2016	$	123,392		$	33,351		$	13,197	$	169,940

Intangible Assets (Tables)

7 Months Ended

Dec. 31, 2016

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,
		2016
	Useful Life (Years)	Gross Amount		Accumulated Amortization			Net Carrying Amount
Customer relationships	5-12	$	81,559	$	(50,417	)	$	31,142
Software/Technology	3-15	18,128		(12,577		)	5,551
Covenants not to compete	2-5	11,143		(9,647		)	1,496
Other	2-5	7,266		(5,448		)	1,818
Total		$	118,096	$	(78,089	)	$	40,007



		May 31,
		2016							2015
	Useful Life (Years)	Gross Amount		Accumulated Amortization			Net Carrying Amount		Gross Amount		Accumulated Amortization			Net Carrying Amount
Customer relationships	5-12	$	81,262	$	(47,747	)	$	33,515	$	81,101	$	(41,009	)	$	40,092
Software/Technology	3-15	17,539		(11,855		)	5,684		15,738		(10,290		)	5,448
Covenants not to compete	2-5	10,791		(9,290		)	1,501		11,678		(8,605		)	3,073
Other	2-5	7,827		(5,035		)	2,792		6,910		(4,247		)	2,663
Total		$	117,419	$	(73,927	)	$	43,492	$	115,427	$	(64,151	)	$	51,276

Schedule of expected amortization expense of intangible assets

Amortization expense in each of the five years and thereafter subsequent to December 31, 2016 related to the Company’s intangible assets is expected to be as follows:



	Expected Amortization Expense

2017	$	8,230
2018	6,783
2019	5,572
2020	4,364
2021	4,040
Thereafter	11,018
Total	$	40,007

Long-Term Debt (Tables)

7 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Schedule of long-term debt

Long-term debt consists of the following:



	December 31,			May 31,
	2016			2016			2015
Senior credit facility	$	82,776		$	68,999		$	83,062
Notes payable	320			10,111			24,632
Other	4,200			5,899			5,765
Total debt	87,296			85,009			113,459
Less: Current portion	(1,379		)	(12,553		)	(17,902		)
Long-term debt, net of current portion	$	85,917		$	72,456		$	95,557

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, 2016 are as follows:



2017	$	1,379
2018	881
2019	83,494
2020	411
2021	194
Thereafter	937
Total	$	87,296

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

+ Details

Fair Value Measurements (Tables)

7 Months Ended

Dec. 31, 2016

Fair Value Disclosures [Abstract]

Schedule of fair value of the Company's financial liabilities that are required to be remeasured at fair value on a recurring basis



	December 31, 2016
	Level 1		Level 2		Level 3		Total
Liabilities:
Contingent consideration	$	—	$	—	$	3,094	$	3,094
Total Liabilities	$	—	$	—	$	3,094	$	3,094



	May 31, 2016
	Level 1		Level 2		Level 3		Total
Liabilities:
Contingent consideration	$	—	$	—	$	2,075	$	2,075
Total Liabilities	$	—	$	—	$	2,075	$	2,075



	May 31, 2015
	Level 1		Level 2		Level 3		Total
Liabilities:
Contingent consideration	$	—	$	—	$	6,411	$	6,411
Total Liabilities	$	—	$	—	$	6,411	$	6,411

Share-Based Compensation (Tables)

7 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of cash proceeds from, and the intrinsic value of, stock options exercised

Cash proceeds from, and the intrinsic value of stock options exercised during the transition period ended December 31, 2016 and the years ended May 31, 2016, 2015 and 2014 were as follows:



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015		2014
Cash proceeds from options exercised	$	604	$	543	$	750	$	996
Aggregate intrinsic value of options exercised	993		658		563		1,247

Summary of stock option activity, weighted average exercise prices, options outstanding and exercisable

A summary of the stock option activity, weighted average exercise prices, options outstanding and exercisable as of December 31, 2016 is as follows (in thousands, except per share amounts):



	For the Transition Period ended December 31,				For the year ended May 31,
	2016				2016				2015				2014
	Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price
Outstanding at beginning of year:	2,232		$	13.21	2,287		$	13.13	2,352		$	13.09	2,464		$	12.93
Granted	—		$	—	—		$	—	—		$	—	—		$	—
Exercised	(65	)	$	9.27	(55	)	$	9.87	(65	)	$	11.54	(103	)	$	9.67
Expired or forfeited	—		$	—	—		$	—	—		$	—	(9	)	$	10.03
Outstanding at end of year:	2,167		$	13.33	2,232		$	13.21	2,287		$	13.13	2,352		$	13.09

Schedule of information concerning outstanding and exercisable options



			For the Transition Period ended December 31, 2016
			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
$6.15-$11.54	72		1.5	$	8.93	72		$	8.93
$13.46-$22.35	2,095		2.7	$	13.48	2,095		$	13.48
	2,167					2,167

Aggregate Intrinsic Value	$	26,760				$	26,760

Summary of restricted stock activity



	For the transition period ended December 31,				For the year ended May 31,
	2016				2016				2015				2014
	Units		Weighted Average Grant-Date Fair Value		Units		Weighted Average Grant-Date Fair Value		Units		Weighted Average Grant-Date Fair Value		Units		Weighted Average Grant-Date Fair Value
Outstanding at beginning of period:	575		$	18.85	564		$	20.47	628		$	19.37	555		$	18.77
Granted	219		$	24.48	264		$	16.73	192		$	21.87	295		$	19.51
Released	(207	)	$	19.40	(223	)	$	20.40	(232	)	$	18.17	(178	)	$	17.70
Forfeited	(18	)	$	19.55	(30	)	$	19.26	(24	)	$	20.57	(44	)	$	19.67
Outstanding at end of period:	569		$	20.81	575		$	18.85	564		$	20.47	628		$	19.37

Summary of performance restricted stock units activity

A summary of the Company's Performance Restricted Stock Unit activity is presented below:



	For the Transition Period ended December 31, 2016
	Units		Weighted Average Grant-Date Fair Value
Outstanding at beginning of period:	328		$	17.02
Granted	105		$	24.90
Performance condition adjustments, net	(54	)	$	24.49
Released	(89	)	$	24.50
Forfeited	—		$	—
Outstanding at end of period:	290		$	16.01

Income Taxes (Tables)

7 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of income before provision for income taxes

Income before provision for income taxes is as follows:



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015			2014
Income (loss) before provision for income taxes from:
U.S. operations	$	5,116	$	27,772	$	26,893		$	25,433
Foreign operations	10,365		10,643		(1,162		)	9,670
Earnings before income taxes	$	15,481	$	38,415	$	25,731		$	35,103

Schedule of provision for income taxes

The provision for income taxes consists of the following:



	For the Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015			2014
Current
Federal	$	1,990		$	9,156		$	8,489		$	8,836
States and local	483			1,537			1,177			1,689
Foreign	3,569			3,672			1,493			2,484
Reserve for uncertain tax positions	(39		)	(529		)	(48		)	59
Total current	6,003			13,836			11,111			13,068
Deferred
Federal	6			82			(145		)	(53		)
States and local	(28		)	(51		)	(126		)	395
Foreign	(514		)	(557		)	(2,416		)	(967		)
Total deferred	(536		)	(526		)	(2,687		)	(625		)
Net change in valuation allowance	403			455			1,316			85
Net deferred	(133		)	(71		)	(1,371		)	(540		)
Provision for income taxes	$	5,870		$	13,765		$	9,740		$	12,528

Schedule of provision for income taxes computed by applying the statutory federal tax rate

The provision for income taxes differs from the amount computed by applying the statutory federal tax rate to income tax as follows:



	For the Transition period ended December 31,
	2016
Federal tax at statutory rate	$	5,418		35.0	%
State taxes, net of federal benefit	296			1.9	%
Foreign tax	(573		)	(3.7	)%
Contingent consideration	(4		)	—	%
Permanent differences	373			2.4	%
Other	(43		)	(0.3	)%
Change in valuation allowance	403			2.6	%
Total provision for income taxes	$	5,870		37.9	%



	For the year ended May 31,
	2016					2015					2014
Federal tax at statutory rate	$	13,445		35.0	%	$	9,006		35.0	%	$	12,286		35.0	%
State taxes, net of federal benefit	966			2.5	%	683			2.7	%	1,355			3.9	%
Foreign tax	(610		)	(1.6	)%	(517		)	(2.0	)%	(1,868		)	(5.3	)%
Contingent consideration	(425		)	(1.1	)%	(914		)	(3.6	)%	24			0.1	%
Permanent differences	245			0.6	%	196			0.8	%	531			1.5	%
Other	(311		)	(0.8	)%	(30		)	(0.1	)%	115			0.3	%
Change in valuation allowance	455			1.2	%	1,316			5.1	%	85			0.2	%
Total provision for income taxes	$	13,765		35.8	%	$	9,740		37.9	%	$	12,528		35.7	%

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,			May 31,
	2016			2016			2015
Deferred income tax assets
Allowance for doubtful accounts	$	969		$	940		$	1,036
Inventory	236			518			796
Intangible assets	2,529			1,641			1,254
Accrued expenses	5,157			4,668			3,455
Net operating loss carryforward	4,094			4,036			4,738
Capital lease obligations	1,140			1,167			379
Capital losses	719			719			—
Deferred share-based compensation	5,802			6,477			6,241
Other	285			440			370
Deferred income tax assets	20,931			20,606			18,269
Valuation allowance	(3,896		)	(3,397		)	(3,238		)
Net deferred income tax assets	17,035			17,209			15,031
Deferred income tax liabilities
Property and equipment	(8,655		)	(9,785		)	(8,214		)
Goodwill	(13,586		)	(12,535		)	(10,728		)
Intangible assets	(5,051		)	(5,989		)	(6,677		)
Other	(11		)	(12		)	(44		)
Deferred income tax liabilities	(27,303		)	(28,321		)	(25,663		)
Net deferred income taxes	$	(10,268	)	$	(11,112	)	$	(10,632	)

Summary 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 Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015
Balance at beginning of period	$	303		$	763		$	1,016
Additions for tax positions related to the current fiscal period	8			29			30
Additions for tax positions related to prior years	—			52			—
Decreases for tax positions related to prior years	(11		)	(23		)	(1		)
Impact of foreign exchange fluctuation	—			(91		)	(112		)
Settlements	—			(29		)	(50		)
Reductions related to the expiration of statutes of limitations	(33		)	(398		)	(120		)
Balance at end of period	$	267		$	303		$	763

Obligations under Capital Leases (Tables)

7 Months Ended

Dec. 31, 2016

Leases [Abstract]

Scheduled future minimum lease payments

Scheduled future minimum lease payments subsequent to December 31, 2016 are as follows:



2017	$	7,033
2018	5,312
2019	3,008
2020	1,191
2021	556
Thereafter	88
Total minimum lease payments	17,188
Less: amount representing interest	(1,018		)
Present value of minimum lease payments	16,170
Less: current portion of obligations under capital leases	(6,488		)
Obligations under capital leases, net of current portion	$	9,682

Segment Disclosure (Tables)

7 Months Ended

Dec. 31, 2016

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 Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015			2014
Revenues
Services	$	293,218		$	553,279		$	540,224		$	443,229
International	104,013			143,025			146,953			161,395
Products and Systems	14,541			30,293			31,255			33,544
Corporate and eliminations	(7,611		)	(7,416		)	(7,180		)	(14,721		)
	$	404,161		$	719,181		$	711,252		$	623,447



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015		2014
Gross profit
Services	$	75,784	$	145,262	$	135,201	$	114,182
International	34,210		43,613		34,572		44,893
Products and Systems	6,920		14,022		14,314		14,495
Corporate and eliminations	90		111		646		(627		)
	$	117,004	$	203,008	$	184,733	$	172,943



	For the Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015			2014
Income from operations
Services	$	22,411		$	52,552		$	49,142		$	43,221
International	10,597			9,293			(575		)	10,238
Products and Systems	(254		)	2,688			2,461			2,552
Corporate and eliminations	(15,221		)	(21,356		)	(20,675		)	(17,716		)
	$	17,533		$	43,177		$	30,353		$	38,295



	For the Transition Period ended December 31,			For the year ended May 31,
	2016			2016			2015		2014
Depreciation and amortization
Services	$	12,765		$	22,725		$	22,268	$	17,794
International	5,306			7,774			8,451		8,065
Products and Systems	1,372			2,323			2,426		2,373
Corporate and eliminations	(244		)	(348		)	141		197
	$	19,199		$	32,474		$	33,286	$	28,429



	December 31,		May 31,
	2016		2016		2015
Intangible assets, net
Services	$	19,550	$	19,022	$	24,598
International	14,139		17,703		19,482
Products and Systems	5,482		6,054		7,004
Corporate and eliminations	836		713		192
	$	40,007	$	43,492	$	51,276



	December 31,		May 31,
	2016		2016		2015
Total assets
Services	$	291,539	$	301,678	$	301,031
International	130,427		132,643		126,643
Products and Systems	28,964		31,596		35,464
Corporate and eliminations	18,497		16,758		8,589
	$	469,427	$	482,675	$	471,727

Schedule of revenue and long-lived assets by geographic area

Revenue and long-lived assets by geographic area was as follows:



	For the Transition Period ended December 31,		For the year ended May 31,
	2016		2016		2015		2014
Revenue
United States	$	256,926	$	519,361	$	491,818	$	403,001
Other Americas	41,777		67,809		68,628		55,120
Europe	91,847		118,566		137,071		143,931
Asia-Pacific	13,611		13,445		13,735		21,395
	$	404,161	$	719,181	$	711,252	$	623,447



	December 31,		May 31,
	2016		2016		2015
Long-lived assets
United States	$	186,960	$	186,543	$	190,997
Other Americas	29,065		29,743		31,558
Europe	67,072		75,102		73,744
Asia-Pacific	—		—		647
	$	283,097	$	291,388	$	296,946

Seven Months Ended December 31, 2015 Comparative Data (Unaudited) Seven Months Ended December 31, 2015 Comparative Data (Unaudited) (Tables)

7 Months Ended

Dec. 31, 2016

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Condensed Consolidated of Income for the Seven Months ended December 31, 2015

The condensed consolidated statement of income for the seven months ended December 31, 2015 is as follows: (In thousands, except per share data)



	Seven Months Ended December 31, 2015
	(unaudited)
Revenues	$	427,913
Cost of revenues	292,718
Depreciation	12,005
Gross profit	123,190
Selling, general and administrative expenses	81,117
Research and engineering	1,431
Depreciation and amortization	6,503
Acquisition-related benefit, net	(959		)
Income from operations	35,098
Interest expense, net	3,672
Income before provision for income taxes	31,426
Provision for income taxes	11,627
Net Income	19,799
Less: Net (loss) attributable to non-controlling interests	(15		)
Net income available to Mistras Group, Inc. shareholders	$	19,814
Net income per share: Basic	$	0.69
Net income per share: Diluted	$	0.67
Weighted average shares outstanding:
Basic	28,810
Diluted	29,676

Selected Quarterly Financial Information (unaudited) (Tables)

7 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Summary of the quarterly results of operations

The following is a summary of the quarterly results of operations for November 30, 2016, August 31, 2016 and the fiscal years ended May 31, 2016 and 2015:



Fiscal quarter ended	November 30, 2016		August 31, 2016		May 31, 2016		February 29, 2016		November 30, 2015		August 31, 2015		May 31, 2015		February 28, 2015		November 30, 2014		August 31, 2014
Revenues	$	176,642	$	168,443	$	184,187	$	160,355	$	194,786	$	179,853	$	174,686	$	163,100	$	206,893	$	166,573
Gross Profit	52,076		50,056		52,000		42,809		56,925		51,274		44,966		38,734		59,039		41,994
Income from operations	12,508		11,155		4,918		5,758		19,569		12,932		4,627		3,870		18,192		3,664
Net income attributable to Mistras Group, Inc.	$	7,270	$	6,596	$	2,764	$	3,593	$	11,425	$	6,872	$	2,171	$	1,817	$	10,427	$	1,666
Earnings per common share:
Basic	$	0.25	$	0.23	$	0.10	$	0.12	$	0.40	$	0.24	$	0.08	$	0.06	$	0.36	$	0.06
Diluted	$	0.24	$	0.22	$	0.09	$	0.12	$	0.39	$	0.23	$	0.07	$	0.06	$	0.35	$	0.06

Description of Business and Basis of Presentation - Additional Information (Details) - International	7 Months Ended
	Dec. 31, 2016 mo subsidiary
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [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
Disposal Of Foreign Subsidiaries \| Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of additional subsidiaries for sale \| subsidiary	2

Summary of Significant Accounting Policies - Additional Information (Details) $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($) customer	May 31, 2016 USD ($) customer	May 31, 2015 USD ($) customer	May 31, 2014 USD ($) customer
Concentration of Credit Risk
Minimum amount of of excess self-insurance claims paid to reduce exposure	$ 0.3
Selling, General and Administrative Expenses
Concentration of Credit Risk
Advertising, promotion and marketing expense	1.2	$ 1.8	$ 2.2	$ 1.8
Foreign currency (gains) and losses	$ (0.7)	$ (0.1)	$ 1.5	$ 0.1
Software/Technology
Concentration of Credit Risk
Estimated useful life of software	3 years
Customer concentration risk \| Revenues
Concentration of Credit Risk
Number of customers \| customer	1	1	0	0
Percentage of concentration risk	12.00%	10.00%	10.00%	10.00%
Customer concentration risk \| Accounts Receivable
Concentration of Credit Risk
Number of customers \| customer	1	1	0
Percentage of concentration risk	11.00%	11.00%	10.00%

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended										7 Months Ended		12 Months Ended
	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	May 31, 2015	May 31, 2014
Basic earnings per share
Net income attributable to Mistras Group, Inc.	$ 7,270	$ 6,596	$ 2,764	$ 3,593	$ 11,425	$ 6,872	$ 2,171	$ 1,817	$ 10,427	$ 1,666	$ 9,568	$ 19,814	$ 24,654	$ 16,081	$ 22,518
Denominator
Weighted average common shares outstanding (in shares)											28,989	28,810	28,856	28,613	28,365
Basic earnings per share (in dollars per share)	$ 0.25	$ 0.23	$ 0.10	$ 0.12	$ 0.40	$ 0.24	$ 0.08	$ 0.06	$ 0.36	$ 0.06	$ 0.33	$ 0.69	$ 0.85	$ 0.56	$ 0.79
Denominator
Weighted average common shares outstanding (in shares)											28,989	28,810	28,856	28,613	28,365
Dilutive effect of stock options outstanding (in shares)											791		712	719	775
Dilutive effect of restricted stock units outstanding (in shares)											345		323	258	184
Weighted average common shares outstanding, diluted (in shares)											30,125	29,676	29,891	29,590	29,324
Diluted earnings per share (in dollars per share)	$ 0.24	$ 0.22	$ 0.09	$ 0.12	$ 0.39	$ 0.23	$ 0.07	$ 0.06	$ 0.35	$ 0.06	$ 0.32	$ 0.67	$ 0.82	$ 0.54	$ 0.77
Earnings per share
Potential common shares excluded from computation of diluted earnings per share (in shares)											2		29	7	126
Potential common stock attributable to stock options outstanding
Earnings per share
Potential common shares excluded from computation of diluted earnings per share (in shares)											0		5	6	5
Potential common stock attributable to performance awards outstanding
Earnings per share
Potential common shares excluded from computation of diluted earnings per share (in shares)											2		24	1	121

Accounts Receivable, net (Details) - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015
Receivables [Abstract]
Trade accounts receivable	$ 133,704	$ 140,820	$ 136,208
Allowance for doubtful accounts	(2,852)	(2,907)	(2,980)
Accounts receivable, net	130,852	137,913	133,228
Accrued unbilled revenues	$ 16,800	$ 18,800	$ 15,000

Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 5,409	$ 3,827	$ 4,194
Work in progress	1,246	1,743	1,604
Finished goods	1,874	2,839	3,178
Services-related consumable supplies	1,488	1,509	1,865
Inventory	$ 10,017	$ 9,918	$ 10,841

Property, Plant and Equipment, net (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 199,972	$ 202,844	$ 190,264
Accumulated depreciation and amortization	(126,823)	(124,168)	(111,008)
Property, plant and equipment, net	73,149	78,676	79,256
Depreciation expense	14,000	22,900	22,200	$ 19,200
Land
Property, Plant and Equipment, net
Property, plant and equipment, gross	1,714	1,735	1,856
Building and improvements
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 19,261	$ 19,364	17,712
Building and improvements \| Minimum
Property, Plant and Equipment, net
Useful Life	30 years	30 years
Building and improvements \| Maximum
Property, Plant and Equipment, net
Useful Life	40 years	40 years
Office furniture and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 9,069	$ 8,692	7,934
Office furniture and equipment \| Minimum
Property, Plant and Equipment, net
Useful Life	5 years	5 years
Office furniture and equipment \| Maximum
Property, Plant and Equipment, net
Useful Life	8 years	8 years
Machinery and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 169,928	$ 173,053	$ 162,762
Machinery and equipment \| Minimum
Property, Plant and Equipment, net
Useful Life	5 years	5 years
Machinery and equipment \| Maximum
Property, Plant and Equipment, net
Useful Life	7 years	7 years

Acquisitions and Dispositions - Narrative (Details)	7 Months Ended	12 Months Ended
Acquisitions and Dispositions - Narrative (Details)	Dec. 31, 2016 USD ($) Entity	May 31, 2016 USD ($) Entity	May 31, 2015 USD ($) Entity	May 31, 2014 USD ($)
Business Acquisition [Line Items]
Period over which potential acquisition-related contingent consideration would be payable	2 years 10 months
Goodwill	$ 169,940,000	$ 169,220,000	$ 166,414,000	$ 130,516,000
Revenue for the period subsequent to closing of the transaction	2,700,000
Aggregate loss from operation for the period subsequent to closing of transaction	$ 100,000
Minimum
Business Acquisition [Line Items]
Amortization period of intangible assets acquired		2 years
Maximum
Business Acquisition [Line Items]
Amortization period of intangible assets acquired		12 years
Acquisitions in Fiscal 2017
Business Acquisition [Line Items]
Number of entities \| Entity	3
Cash paid	$ 8,295,000
Notes payable	325,000
Contingent consideration	1,630,000
Potential acquisition-related contingent consideration, low end of range		$ 0
Potential acquisition-related contingent consideration, high end of range		$ 2,600,000
Goodwill	$ 4,120,000
Acquisitions in Fiscal 2017 \| Canada
Business Acquisition [Line Items]
Percentage of common stock acquired	100.00%
Cash paid	$ 1,300,000
Notes payable	300,000
Contingent consideration	$ 400,000
Period over which potential acquisition-related contingent consideration would be payable	3 years
Acquisitions in Fiscal 2017 \| Canada \| NDT Services
Business Acquisition [Line Items]
Number of entities \| Entity	2
Acquisitions in Fiscal 2017 \| United States
Business Acquisition [Line Items]
Cash paid	$ 7,000,000
Contingent consideration	$ 1,200,000
Period over which potential acquisition-related contingent consideration would be payable	3 years
Acquisitions in Fiscal 2017 \| United States \| Mechanical Services
Business Acquisition [Line Items]
Number of entities \| Entity	1
Acquisitions in Fiscal 2016
Business Acquisition [Line Items]
Number of entities \| Entity		2
Cash paid		$ 1,784,000
Notes payable		0
Contingent consideration		991,000
Potential acquisition-related contingent consideration, low end of range		0
Potential acquisition-related contingent consideration, high end of range	$ 300,000
Goodwill		$ 2,728,000
Maximum fair value measurement period from the acquisition date	1 year
Acquisitions in Fiscal 2016 \| United States
Business Acquisition [Line Items]
Number of entities \| Entity		2
Percentage of common stock acquired		100.00%
Cash paid		$ 1,800,000
Contingent consideration		$ 1,000,000
Period over which potential acquisition-related contingent consideration would be payable		4 years
Acquisitions in Fiscal 2015
Business Acquisition [Line Items]
Number of entities \| Entity			4
Percentage of common stock acquired			100.00%
Cash paid			$ 35,755,000
Notes payable			20,505,000
Contingent consideration			$ 2,255,000
Period over which potential acquisition-related contingent consideration would be payable			3 years
Potential acquisition-related contingent consideration, low end of range			$ 0
Potential acquisition-related contingent consideration, high end of range			$ 3,200,000
Debt instrument, term			2 years
Goodwill			$ 46,312,000
Acquisitions in Fiscal 2015 \| United States
Business Acquisition [Line Items]
Number of entities \| Entity			1

Acquisitions and Dispositions - Estimated Fair Value of the Assets Acquired and Liabilities Assumed (Details) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($) Entity	May 31, 2016 USD ($) Entity	May 31, 2015 USD ($) Entity	May 31, 2014 USD ($)
Estimated fair value of the assets acquired and liabilities assumed
Goodwill	$ 169,940	$ 169,220	$ 166,414	$ 130,516
Acquisitions in Fiscal 2017
Acquisitions
Number of entities \| Entity	3
Consideration transferred:
Cash paid	$ 8,295
Notes payable	325
Contingent consideration	1,630
Consideration paid	10,250
Estimated fair value of the assets acquired and liabilities assumed
Current net assets	1,632
Debt and other long-term liabilities	(214)
Property, plant and equipment	953
Deferred tax asset (liability)	392
Intangibles	3,367
Goodwill	4,120
Net assets acquired	$ 10,250
Acquisitions in Fiscal 2016
Acquisitions
Number of entities \| Entity		2
Consideration transferred:
Cash paid		$ 1,784
Notes payable		0
Contingent consideration		991
Consideration paid		2,775
Estimated fair value of the assets acquired and liabilities assumed
Current net assets		180
Debt and other long-term liabilities		(546)
Property, plant and equipment		485
Deferred tax asset (liability)		(72)
Intangibles		0
Goodwill		2,728
Net assets acquired		$ 2,775
Acquisitions in Fiscal 2015
Acquisitions
Number of entities \| Entity			4
Consideration transferred:
Cash paid			$ 35,755
Notes payable			20,505
Contingent consideration			2,255
Consideration paid			58,515
Estimated fair value of the assets acquired and liabilities assumed
Current net assets			2,770
Debt and other long-term liabilities			(5,889)
Property, plant and equipment			7,395
Deferred tax asset (liability)			(2,467)
Intangibles			10,394
Goodwill			46,312
Net assets acquired			$ 58,515

Acquisitions and Dispositions - Dispositions Narrative (Details) $ in Thousands		7 Months Ended	12 Months Ended
	May 22, 2015 USD ($) subsidiary	Dec. 31, 2016 USD ($)	May 31, 2016 USD ($)	May 31, 2015 USD ($) subsidiary	May 31, 2014 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Losses associated with the exit of foreign operations		$ 0	$ 0	$ 2,516	$ 0
International \| Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations \| Disposal Of Foreign Subsidiaries
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of foreign subsidiaries sold and held-for-sale \| subsidiary				3
Disposal group, percentage of assets to consolidated assets				0.60%
Disposal group, percentage of liabilities to consolidated liabilities				0.30%
International \| Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations \| Disposal Of Foreign Subsidiaries \| Russia
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of subsidiaries sold \| subsidiary	1
Losses associated with the exit of foreign operations	$ 400
International \| Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations \| Disposal Of Foreign Subsidiaries \| Russia and Japan
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Losses associated with the exit of foreign operations				$ 2,500
Impairment charges on subsidiaries held-for-sale				$ 2,100

Acquisitions and Dispositions - Acquisition-Related Expense (Details) - USD ($) $ in Thousands	7 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	May 31, 2015	May 31, 2014
Business Acquisition [Line Items]
Adjustments to fair value of contingent consideration liabilities	$ 262		$ (2,066)	$ (5,382)	$ (3,937)
Acquisition-related (benefit) expense, net	496	$ (959)	(1,453)	(5,167)	(2,657)
Acquisitions in Fiscal 2017
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 in Fiscal 2015
Business Acquisition [Line Items]
Due diligence, professional fees and other transaction costs				215
Adjustments to fair value of contingent consideration liabilities				(5,382)
Acquisition-related (benefit) expense, net				$ (5,167)
Acquisitions in Fiscal 2014
Business Acquisition [Line Items]
Due diligence, professional fees and other transaction costs					1,280
Adjustments to fair value of contingent consideration liabilities					(3,937)
Acquisition-related (benefit) expense, net					$ (2,657)

Goodwill (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
Changes in the carrying amount of goodwill
Balance at the beginning of the period	$ 169,220	$ 166,414	$ 130,516
Goodwill acquired (disposed) during the year	4,120	2,354	43,466
Adjustments to preliminary purchase price allocations	(19)	270	3,162
Foreign currency translation	(3,381)	182	(10,730)
Balance at the end of the period	169,940	169,220	166,414
Services
Changes in the carrying amount of goodwill
Balance at the beginning of the period	119,683	117,279	73,767
Goodwill acquired (disposed) during the year	4,120	2,728	41,986
Adjustments to preliminary purchase price allocations	(19)	270	3,529
Foreign currency translation	(392)	(594)	(2,003)
Balance at the end of the period	123,392	119,683	117,279
International
Changes in the carrying amount of goodwill
Balance at the beginning of the period	36,340	35,938	43,552
Goodwill acquired (disposed) during the year	0	(374)	1,480
Adjustments to preliminary purchase price allocations	0	0	(367)
Foreign currency translation	(2,989)	776	(8,727)
Balance at the end of the period	33,351	36,340	35,938
Goodwill, cumulative impairment charge	9,900	9,900	9,900	$ 9,900
Products
Changes in the carrying amount of goodwill
Balance at the beginning of the period	13,197	13,197	13,197
Goodwill acquired (disposed) during the year	0	0	0
Adjustments to preliminary purchase price allocations	0	0	0
Foreign currency translation	0	0	0
Balance at the end of the period	$ 13,197	$ 13,197	$ 13,197

Intangible Assets - Gross Carrying Amount and Accumulated Amortization (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
Intangible assets
Gross Amount	$ 118,096	$ 117,419	$ 115,427
Accumulated Amortization	(78,089)	(73,927)	(64,151)
Net Carrying Amount	40,007	43,492	51,276
Amortization expense	5,200	9,600	11,100	$ 9,200
Customer relationships
Intangible assets
Gross Amount	81,559	81,262	81,101
Accumulated Amortization	(50,417)	(47,747)	(41,009)
Net Carrying Amount	$ 31,142	$ 33,515	40,092
Customer relationships \| Minimum
Intangible assets
Useful Life (Years)	5 years	5 years
Customer relationships \| Maximum
Intangible assets
Useful Life (Years)	12 years	12 years
Software/Technology
Intangible assets
Useful Life (Years)	3 years
Gross Amount	$ 18,128	$ 17,539	15,738
Accumulated Amortization	(12,577)	(11,855)	(10,290)
Net Carrying Amount	5,551	5,684	5,448
Amortization expense	$ 500	$ 1,000	900	$ 900
Software/Technology \| Minimum
Intangible assets
Useful Life (Years)	3 years	3 years
Software/Technology \| Maximum
Intangible assets
Useful Life (Years)	15 years	15 years
Covenants not to compete
Intangible assets
Gross Amount	$ 11,143	$ 10,791	11,678
Accumulated Amortization	(9,647)	(9,290)	(8,605)
Net Carrying Amount	$ 1,496	$ 1,501	3,073
Covenants not to compete \| Minimum
Intangible assets
Useful Life (Years)	2 years	2 years
Covenants not to compete \| Maximum
Intangible assets
Useful Life (Years)	5 years	5 years
Other
Intangible assets
Gross Amount	$ 7,266	$ 7,827	6,910
Accumulated Amortization	(5,448)	(5,035)	(4,247)
Net Carrying Amount	$ 1,818	$ 2,792	$ 2,663
Other \| Minimum
Intangible assets
Useful Life (Years)	2 years	2 years
Other \| Maximum
Intangible assets
Useful Life (Years)	5 years	5 years

Intangible Assets - Expected Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
2017	$ 8,230
2018	6,783
2019	5,572
2020	4,364
2021	4,040
Thereafter	11,018
Net Carrying Amount	$ 40,007	$ 43,492	$ 51,276

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015
Payables and Accruals [Abstract]
Accrued salaries, wages and related employee benefits	$ 23,442	$ 31,566	$ 26,053
Contingent consideration	1,826	1,029	3,543
Accrued workers' compensation and health benefits	6,351	4,834	3,630
Deferred revenues	3,743	3,332	3,841
Legal settlement accrual	6,320	6,320	0
Other accrued expenses	17,015	15,902	18,847
Total accrued expenses and other current liabilities	$ 58,697	$ 62,983	$ 55,914

Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015
Debt Instrument [Line Items]
Total debt	$ 87,296	$ 85,009	$ 113,459
Less: Current portion	(1,379)	(12,553)	(17,902)
Long-term debt, net of current portion	85,917	72,456	95,557
Senior credit facility
Debt Instrument [Line Items]
Total debt	82,776	68,999	83,062
Notes payable
Debt Instrument [Line Items]
Total debt	320	10,111	24,632
Other
Debt Instrument [Line Items]
Total debt	$ 4,200	$ 5,899	$ 5,765

Long-Term Debt - Narrative (Details)		7 Months Ended
Long-Term Debt - Narrative (Details)	Oct. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) Quarter	Oct. 30, 2014 USD ($)
Senior credit facility
Long-Term Debt
Maximum borrowing capacity	$ 175,000,000.0		$ 125,000,000.0
Higher borrowing capacity option	225,000,000.0
Maximum borrowing capacity in non-U.S. Dollar currencies	30,000,000.0
Maximum amount available for the issuance of letters of credit	$ 10,000,000.0
Long-term line of credit		$ 82,800,000
Outstanding letters of credit		5,700,000
Capitalized debt modification costs		$ 700,000
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		2.0
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
Senior credit facility \| Minimum
Long-Term Debt
Interest coverage ratio		3.0
Senior credit facility \| Maximum
Long-Term Debt
Funded Debt Leverage Ratio at which the entity will have the benefit of lowest interest margin		0.5
Funded Debt Leverage Ratio for additional interest payment		3.25
Senior credit facility \| LIBOR
Long-Term Debt
Reference rate, description	LIBOR
Senior credit facility \| LIBOR \| Minimum
Long-Term Debt
Margin (as a percent)	1.00%
Senior credit facility \| LIBOR \| Maximum
Long-Term Debt
Margin (as a percent)	1.75%
Senior credit facility \| Base rate
Long-Term Debt
Reference rate, description	base rate
Senior credit facility \| Base rate \| Minimum
Long-Term Debt
Margin (as a percent)	(1.25%)
Senior credit facility \| Base rate \| Maximum
Long-Term Debt
Margin (as a percent)	(0.375%)
Notes payable
Long-Term Debt
Maturity term from the date of acquisition		3 years
Interest rate, minimum (as a percent)		2.70%

Long-Term Debt - Principal Payments Due Under All Borrowing Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015
Debt Disclosure [Abstract]
2017	$ 1,379
2018	881
2019	83,494
2020	411
2021	194
Thereafter	937
Total debt	$ 87,296	$ 85,009	$ 113,459

Fair Value Measurements (Details) - Recurring basis - USD ($) $ in Thousands	Dec. 31, 2016	May 31, 2016	May 31, 2015
Liabilities:
Contingent consideration	$ 3,094	$ 2,075	$ 6,411
Total Liabilities	3,094	2,075	6,411
Level 1
Liabilities:
Contingent consideration	0	0	0
Total Liabilities	0	0	0
Level 2
Liabilities:
Contingent consideration	0	0	0
Total Liabilities	0	0	0
Level 3
Liabilities:
Contingent consideration	3,094	2,075	6,411
Total Liabilities	$ 3,094	$ 2,075	$ 6,411

Share-Based Compensation - Additional Information (Details)	7 Months Ended
	Dec. 31, 2016 plan shares	May 31, 2016 shares	May 31, 2015 shares	May 31, 2014 shares	May 31, 2013 shares
Share-based compensation
Number of employee stock ownership plans \| plan	3
Stock option awards
Share-based compensation
Stock options outstanding (in shares)	2,167,000	2,232,000	2,287,000	2,352,000	2,464,000
Restricted Stock Unit Awards
Share-based compensation
Unvested restricted stock units outstanding (in shares)	569,000	575,000	564,000	628,000	555,000
2007 Plan
Share-based compensation
Number of awards that may be granted (in shares)	0
2009 Plan
Share-based compensation
Number of awards that may be granted (in shares)	0
2016 Plan
Share-based compensation
Number of awards that may be granted (in shares)	1,700,000
Number of shares authorized for grants (in shares)	1,700,000
2007 and 2009 Plans \| Stock option awards
Share-based compensation
Stock options outstanding (in shares)	2,167,000
2007 and 2009 Plans \| Restricted Stock Unit Awards
Share-based compensation
Unvested restricted stock units outstanding (in shares)	858,000

Share-Based Compensation - Stock Options Narrative (Details) - Stock option awards - USD ($)	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
Share-based compensation
Recognized share-based compensation expense	$ 0	$ 100,000	$ 100,000	$ 700,000
Stock options granted (in shares)	0	0	0	0
Unrecognized compensation costs related to stock options	$ 0
Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans and Aggregate Intrinsic Value Including Stock Options [Abstract]
Cash proceeds from options exercised	604,000	$ 543,000	$ 750,000	$ 996,000
Aggregate intrinsic value of options exercised	$ 993,000	$ 658,000	$ 563,000	$ 1,247,000

Share-Based Compensation - Stock Option Activity (Details) - Stock option awards - $ / shares	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
Common Stock Options (shares)
Outstanding at beginning of year: (in shares)	2,232,000	2,287,000	2,352,000	2,464,000
Granted (in shares)	0	0	0	0
Exercised (in shares)	(65,000)	(55,000)	(65,000)	(103,000)
Expired or forfeited (in shares)	0	0	0	(9,000)
Outstanding at end of year: (in shares)	2,167,000	2,232,000	2,287,000	2,352,000
Weighted Average Exercise Price (in dollar per share)
Outstanding at beginning of year: (in dollars per share)	$ 13.21	$ 13.13	$ 13.09	$ 12.93
Granted (in dollars per share)	0.00	0.00	0.00	0.00
Exercised (in dollars per share)	9.27	9.87	11.54	9.67
Expired or forfeited (in dollars per share)	0.00	0.00	0.00	10.03
Outstanding at end of year: (in dollars per share)	$ 13.33	$ 13.21	$ 13.13	$ 13.09

Share-Based Compensation - Stock Options Outstanding and Exercisable (Details) $ / shares in Units, shares in Thousands, $ in Thousands	7 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Options Outstanding
Total Options Outstanding (in shares) \| shares	2,167
Options Exercisable
Number Exercisable (in shares) \| shares	2,167
Aggregate Intrinsic Value
Options Outstanding (in dollars) \| $	$ 26,760
Options Exercisable (in dollars) \| $	$ 26,760
$6.15-$11.54
Options Outstanding
Total Options Outstanding (in shares) \| shares	72
Weighted Average Remaining Life (Years)	1 year 6 months
Weighted Average Exercise Price (in dollars per share)	$ 8.93
Options Exercisable
Number Exercisable (in shares) \| shares	72
Weighted Average Exercise Price (in dollars per share)	$ 8.93
Aggregate Intrinsic Value
Range of Exercise Prices, Lower Limit (in dollars per share)	6.15
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 11.54
$13.46-$22.35
Options Outstanding
Total Options Outstanding (in shares) \| shares	2,095
Weighted Average Remaining Life (Years)	2 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
Aggregate Intrinsic Value
Range of Exercise Prices, Lower Limit (in dollars per share)	13.46
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 22.35

Share-Based Compensation - Restricted Stock Units Awards Narrative (Details) shares in Thousands, $ in Millions	7 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($) director shares	May 31, 2016 USD ($) director shares	May 31, 2015 USD ($) director shares	May 31, 2014 USD ($) director shares
Non-employee directors
Share-based compensation
Number of non-employee directors to whom fully vested common stock is granted \| director		5	5	5
Restricted Stock Unit Awards
Share-based compensation
Recognized share-based compensation expense \| $	$ 2.6	$ 4.4	$ 4.7	$ 4.0
Unrecognized compensation cost, net of estimated forfeitures, related to restricted stock unit awards \| $	$ 9.4
Weighted-average period over which unrecognized compensation cost is expected to be recognized	2 years 8 months 3 days
Number of restricted stocks vested (in shares) \| shares	207	223	232	178
Fair value of shares vested \| $	$ 5.1	$ 3.5	$ 5.2	$ 3.3
Number of restricted stocks units granted (in shares) \| shares	219	264	192	295
Restricted Stock Unit Awards \| Non-employee directors
Share-based compensation
Fair value of shares vested \| $	$ 0.3	$ 0.5	$ 0.4	$ 0.4
Number of restricted stocks units granted (in shares) \| shares	10
Number of non-employee directors to whom fully vested common stock is granted \| director	5
Number of fully vested common stock granted (in shares) \| shares		28	21	19

Share-Based Compensation - Restricted Stock Awards Outstanding (Details) - Restricted Stock Unit Awards - $ / shares shares in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014	May 31, 2013
Units
Outstanding at beginning of period: (in shares)	575	564	628	555
Granted (in shares)	219	264	192	295
Released (in shares)	(207)	(223)	(232)	(178)
Forfeited (in shares)	(18)	(30)	(24)	(44)
Outstanding at end of period: (in shares)	569	575	564	628
Weighted Average Grant-Date Fair Value
Outstanding at beginning of period: (in dollars per share)	$ 20.81	$ 18.85	$ 20.47	$ 19.37	$ 18.77
Granted (in dollars per share)	24.48	16.73	21.87	19.51
Released (in dollars per share)	19.40	20.40	18.17	17.70
Forfeited (in dollars per share)	19.55	19.26	20.57	19.67
Outstanding at end of period: (in dollars per share)	$ 20.81	$ 18.85	$ 20.47	$ 19.37	$ 18.77

Share-Based Compensation - Performance Restricted Stock Units Narrative (Details) - USD ($) shares in Thousands, $ in Millions	3 Months Ended	7 Months Ended	12 Months Ended
	Aug. 31, 2015	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
PRSUs
Share-based compensation
Number of restricted stocks units granted (in shares)		105
Unvested restricted stock units outstanding (in shares)		290	328
Executive and senior officers
Share-based compensation
Income tax benefit recognized on share-based compensation		$ 1.6	$ 2.2	$ 2.3	$ 2.3
Executive and senior officers \| PRSUs
Share-based compensation
Unvested restricted stock units outstanding (in shares)			290
Recognized share-based compensation expense		1.7	$ 1.6	$ 1.5	$ 1.2
Unrecognized compensation cost, net of estimated forfeitures, related to restricted stock unit awards		2.8
Weighted-average period over which unrecognized compensation cost is expected to be recognized			2 years
Fiscal 2017 Grants \| PRSUs \| Accrued Expenses and Other Current Liabilities
Share-based compensation
Aggregate liability related to performance shares outstanding		$ 0.1
Fiscal 2017 Grants \| Executive and senior officers \| PRSUs
Share-based compensation
Number of restricted stocks units granted (in shares)		105
Reduction in number of shares authorized for grant (in shares)		(73)
Unvested restricted stock units outstanding (in shares)		12
Fiscal 2017 Grants \| Executive and senior officers \| Performance Restricted Stock Units with three year EPS performance condition
Share-based compensation
Payout performance period		1 year
Requisite service period		5 years
Fiscal 2017 Grants \| Executive and senior officers \| Performance Restricted Stock Units with three year EPS performance condition \| 1st Anniversary
Share-based compensation
Vesting period		4 years
Fiscal 2017 Grants \| Executive and senior officers \| Performance Restricted Stock Units with three year EPS performance condition \| 2nd Anniversary
Share-based compensation
Vesting period		2 years
Fiscal 2017 Grants \| Executive and senior officers \| Performance Restricted Stock Units with three year EPS performance condition \| 3rd Anniversary
Share-based compensation
Vesting period		3 years
Fiscal 2017 Grants \| Executive and senior officers \| Performance Restricted Stock Units with three year EPS performance condition \| 4th Anniversary
Share-based compensation
Vesting period		4 years
Fiscal 2014 Grants \| Executive and senior officers \| PRSUs
Share-based compensation
Requisite service period			3 years
Fiscal 2014 Grants \| Executive and senior officers \| Performance Restricted Stock Units with three year EPS performance condition
Share-based compensation
Award performance period			3 years
Fiscal 2014 Grants \| Executive and senior officers \| Performance Restricted Stock Units with one year EPS performance condition
Share-based compensation
Award performance period			1 year
Payout for the fiscal 2014 market condition awards, percentage of target			170.00%
Fiscal 2014 Grants \| Executive and senior officers \| Performance Restricted Stock Units with two year EPS performance condition
Share-based compensation
Award performance period			2 years
Payout for the fiscal 2014 market condition awards, percentage of target			105.00%
Fiscal 2015 Grants \| Executive and senior officers \| PRSUs
Share-based compensation
Requisite service period			3 years
Fiscal 2016 Grants \| Executive and senior officers \| PRSUs
Share-based compensation
Requisite service period			5 years
Number of fully vested common stock granted (in shares)	154
Increase in number of shares authorized for grant (in shares)			104
Number of shares authorized for grants (in shares)			258

Share-Based Compensation - Performance Restricted Stock Units Activity (Details) - PRSUs - $ / shares shares in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016
Units
Outstanding at beginning of period: (in shares)	328
Granted (in shares)	105
Performance condition adjustments, net (in shares)	(54)
Released (in shares)	(89)
Forfeited (in shares)	0
Outstanding at end of period: (in shares)	290	328
Weighted Average Grant-Date Fair Value
Outstanding at beginning of period: (in dollars per share)	$ 16.01	$ 17.02
Granted (in dollars per share)	24.90
Performance condition adjustments, net (in dollars per share)	24.49
Released (in dollars per share)	24.50
Forfeited (in dollars per share)	0.00
Outstanding at end of period: (in dollars per share)	$ 16.01	$ 17.02

Income Taxes - Income Tax Provision (Details) - USD ($) $ in Thousands	7 Months Ended		12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	May 31, 2015	May 31, 2014
Income (loss) before provision for income taxes from:
U.S. operations	$ 5,116		$ 27,772	$ 26,893	$ 25,433
Foreign operations	10,365		10,643	(1,162)	9,670
Income before provision for income taxes	15,481	$ 31,426	38,415	25,731	35,103
Current
Federal	1,990		9,156	8,489	8,836
States and local	483		1,537	1,177	1,689
Foreign	3,569		3,672	1,493	2,484
Reserve for uncertain tax positions	(39)		(529)	(48)	59
Total current	6,003		13,836	11,111	13,068
Deferred
Federal	6		82	(145)	(53)
States and local	(28)		(51)	(126)	395
Foreign	(514)		(557)	(2,416)	(967)
Total deferred	(536)		(526)	(2,687)	(625)
Net change in valuation allowance	403		455	1,316	85
Net deferred	(133)		(71)	(1,371)	(540)
Provision for income taxes	5,870	11,627	13,765	9,740	12,528
Reconciliation of income tax expense at the statutory rate to the effective income tax expense
Federal tax at statutory rate	5,418		13,445	9,006	12,286
State taxes, net of federal benefit	296		966	683	1,355
Foreign tax	(573)		(610)	(517)	(1,868)
Contingent consideration	(4)		(425)	(914)	24
Permanent differences	373		245	196	531
Other	(43)		(311)	(30)	115
Change in valuation allowance	403		455	1,316	85
Total provision for income taxes	$ 5,870	$ 11,627	$ 13,765	$ 9,740	$ 12,528
Reconciliation of the federal income tax expense (as a percent)
Federal tax at statutory rate	35.00%		35.00%	35.00%	35.00%
State taxes, net of federal benefit	1.90%		2.50%	2.70%	3.90%
Foreign tax	(3.70%)		(1.60%)	(2.00%)	(5.30%)
Contingent consideration	0.00%		(1.10%)	(3.60%)	0.10%
Permanent differences	2.40%		0.60%	0.80%	1.50%
Other	(0.30%)		(0.80%)	(0.10%)	0.30%
Change in valuation allowance	2.60%		1.20%	5.10%	0.20%
Total provision for income taxes	37.90%		35.80%	37.90%	35.70%

Income Taxes - Deferred Income Tax (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015
Deferred income tax assets
Allowance for doubtful accounts	$ 969	$ 940	$ 1,036
Inventory	236	518	796
Intangible assets	2,529	1,641	1,254
Accrued expenses	5,157	4,668	3,455
Net operating loss carryforward	4,094	4,036	4,738
Capital lease obligations	1,140	1,167	379
Capital losses	719	719	0
Deferred share-based compensation	5,802	6,477	6,241
Other	285	440	370
Deferred income tax assets	20,931	20,606	18,269
Valuation allowance	(3,896)	(3,397)	(3,238)
Net deferred income tax assets	17,035	17,209	15,031
Deferred income tax liabilities
Property and equipment	(8,655)	(9,785)	(8,214)
Goodwill	(13,586)	(12,535)	(10,728)
Intangible assets	(5,051)	(5,989)	(6,677)
Other	(11)	(12)	(44)
Deferred income tax liabilities	(27,303)	(28,321)	(25,663)
Net deferred income taxes	(10,268)	(11,112)	(10,632)
Changes in company's gross unrecognized tax benefits, excluding interest and penalties
Balance at beginning of period	303	763	1,016
Additions for tax positions related to the current fiscal period	8	29	30
Additions for tax positions related to prior years	0	52	0
Decreases for tax positions related to prior years	(11)	(23)	(1)
Impact of foreign exchange fluctuation	0	(91)	(112)
Settlements	0	(29)	(50)
Reductions related to the expiration of statutes of limitations	(33)	(398)	(120)
Balance at end of period	$ 267	$ 303	$ 763

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended										7 Months Ended		12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	May 31, 2015	May 31, 2014
Operating Loss Carryforwards [Line Items]
Deferred tax assets valuation allowance			$ 3,397,000				$ 3,238,000				$ 3,896,000		$ 3,397,000	$ 3,238,000
Unrecognized tax benefits including penalties and interest, that would affect the effective tax rate, if recognized			400,000				1,100,000				300,000		400,000	1,100,000
Anticipated decrease in unrecognized tax benefits, excluding interest and penalties within the next 12 months											100,000
Net income (loss) of foreign subsidiaries	$ 7,270,000	$ 6,596,000	$ 2,764,000	$ 3,593,000	$ 11,425,000	$ 6,872,000	$ 2,171,000	$ 1,817,000	$ 10,427,000	$ 1,666,000	9,568,000	$ 19,814,000	24,654,000	16,081,000	$ 22,518,000
Deferred tax liability recognized for the remittance of undistributed international earnings											0
State
Operating Loss Carryforwards [Line Items]
Net operating losses											15,100,000
Foreign
Operating Loss Carryforwards [Line Items]
Net operating losses											12,200,000
Increase in valuation allowance due to losses in foreign subsidiaries											500,000
Net income (loss) of foreign subsidiaries											6,900,000		$ 7,500,000	$ (800,000)
Foreign \| Expiration Period 2021-2036
Operating Loss Carryforwards [Line Items]
Net operating losses											1,400,000
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											3,900,000
Internal Revenue Service (IRS) \| Federal
Operating Loss Carryforwards [Line Items]
Net operating losses											$ 300,000

Employee Benefit Plans (Details) - USD ($) $ in Millions	7 Months Ended	12 Months Ended
Employee Benefit Plans (Details) - USD ($) $ in Millions	Dec. 31, 2016	May 31, 2016	May 31, 2015	May 31, 2014
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	$ 1.9	$ 3.3	$ 2.8	$ 2.5
Amount of employers contribution to the union plan	$ 0.1	$ 0.2	$ 0.2	$ 0.1

Related Party Transactions (Details) - USD ($) $ in Millions	7 Months Ended
	Dec. 31, 2016	Aug. 17, 2016
Shareholder and officer
Related Party Transactions
Total rent payments	$ 0.5
Shareholder and officer \| France
Related Party Transactions
Total rent payments	0.1
Shareholder and officer \| Brazil
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)		1,000,000

Obligations under Capital Leases (Details) - USD ($) $ in Thousands	7 Months Ended
	Dec. 31, 2016	May 31, 2016	May 31, 2015
Obligations under capital leases
Net book value of assets under capital lease	$ 17,600	$ 19,800	$ 19,900
Future minimum lease payments
2017	7,033
2018	5,312
2019	3,008
2020	1,191
2021	556
Thereafter	88
Total minimum lease payments	17,188
Less: amount representing interest	(1,018)
Present value of minimum lease payments	16,170
Less: current portion of obligations under capital leases	(6,488)	(7,835)	(8,646)
Obligations under capital leases, net of current portion	9,682	$ 11,932	$ 10,717
Minimum
Obligations under capital leases
Required monthly payments	$ 1
Effective interest rate (as a percent)	1.00%
Maximum
Obligations under capital leases
Required monthly payments	$ 76
Effective interest rate (as a percent)	8.00%

Commitments and Contingencies (Details)		1 Months Ended	3 Months Ended	7 Months Ended	12 Months Ended
Commitments and Contingencies (Details)	Nov. 30, 2016 USD ($)	Oct. 31, 2016 plaintiff	May 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	May 31, 2016 USD ($)	May 31, 2015 USD ($)	May 31, 2014 USD ($)
Future minimum lease payments
2017				$ 9,390,000
2018				8,068,000
2019				6,115,000
2020				4,566,000
2021				3,603,000
Thereafter				11,609,000
Total				43,351,000
Total rent expense				6,600,000	$ 11,200,000	$ 10,600,000	$ 9,500,000
Litigation
Payroll taxes and other cost related to settlement				$ 0	$ 6,320,000	$ 0	$ 0
Period over which potential acquisition-related contingent consideration would be payable				2 years 10 months
Consolidated class and collective action lawsuit
Litigation
Litigation settlement				$ 6,000,000
Payroll taxes and other cost related to settlement			$ 6,300,000
Loss contingency, number of plaintiffs \| plaintiff		4,900
Lawsuits for alleged quality defects
Litigation
Verbal demand for damages	$ 6,000,000
Dispute with former owner of company's French subsidiary \| French Subsidiary
Litigation
Litigation settlement			$ 400,000
Damages from Product Defects \| Ultrasonic Inspection System
Litigation
Verbal demand for damages				2,300,000
Acquisition-related contingencies
Litigation
Potential acquisition-related contingent consideration, low end of range				0
Potential acquisition-related contingent consideration, high end of range				$ 15,200,000

Segment Disclosure - Financial Information (Details) $ in Thousands	3 Months Ended										7 Months Ended		12 Months Ended
	Nov. 30, 2016 USD ($)	Aug. 31, 2016 USD ($)	May 31, 2016 USD ($)	Feb. 29, 2016 USD ($)	Nov. 30, 2015 USD ($)	Aug. 31, 2015 USD ($)	May 31, 2015 USD ($)	Feb. 28, 2015 USD ($)	Nov. 30, 2014 USD ($)	Aug. 31, 2014 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	May 31, 2016 USD ($) Operating_Segment	May 31, 2015 USD ($)	May 31, 2014 USD ($)
Segment Reporting [Abstract]
Number of operating segments \| Operating_Segment													3
Financial information by segment
Revenue	$ 176,642	$ 168,443	$ 184,187	$ 160,355	$ 194,786	$ 179,853	$ 174,686	$ 163,100	$ 206,893	$ 166,573	$ 404,161	$ 427,913	$ 719,181	$ 711,252	$ 623,447
Gross Profit	52,076	50,056	52,000	42,809	56,925	51,274	44,966	38,734	59,039	41,994	117,004	123,190	203,008	184,733	172,943
Income from operations	$ 12,508	$ 11,155	4,918	$ 5,758	$ 19,569	$ 12,932	4,627	$ 3,870	$ 18,192	$ 3,664	17,533	$ 35,098	43,177	30,353	38,295
Depreciation and amortization											19,199		32,474	33,286	28,429
Intangible assets, net			43,492				51,276				40,007		43,492	51,276
Total assets			482,675				471,727				469,427		482,675	471,727
Operating segments \| Services
Financial information by segment
Revenue											293,218		553,279	540,224	443,229
Gross Profit											75,784		145,262	135,201	114,182
Income from operations											22,411		52,552	49,142	43,221
Depreciation and amortization											12,765		22,725	22,268	17,794
Intangible assets, net			19,022				24,598				19,550		19,022	24,598
Total assets			301,678				301,031				291,539		301,678	301,031
Operating segments \| International
Financial information by segment
Revenue											104,013		143,025	146,953	161,395
Gross Profit											34,210		43,613	34,572	44,893
Income from operations											10,597		9,293	(575)	10,238
Depreciation and amortization											5,306		7,774	8,451	8,065
Intangible assets, net			17,703				19,482				14,139		17,703	19,482
Total assets			132,643				126,643				130,427		132,643	126,643
Operating segments \| Products and Systems
Financial information by segment
Revenue											14,541		30,293	31,255	33,544
Gross Profit											6,920		14,022	14,314	14,495
Income from operations											(254)		2,688	2,461	2,552
Depreciation and amortization											1,372		2,323	2,426	2,373
Intangible assets, net			6,054				7,004				5,482		6,054	7,004
Total assets			31,596				35,464				28,964		31,596	35,464
Corporate and eliminations
Financial information by segment
Revenue											(7,611)		(7,416)	(7,180)	(14,721)
Gross Profit											90		111	646	(627)
Income from operations											(15,221)		(21,356)	(20,675)	(17,716)
Depreciation and amortization											(244)		(348)	141	$ 197
Intangible assets, net			713				192				836		713	192
Total assets			$ 16,758				$ 8,589				$ 18,497		$ 16,758	$ 8,589

Segment Disclosure - Revenue and Long-lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended										7 Months Ended		12 Months Ended
	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	May 31, 2015	May 31, 2014
Revenue and long-lived assets by geographic area
Revenue	$ 176,642	$ 168,443	$ 184,187	$ 160,355	$ 194,786	$ 179,853	$ 174,686	$ 163,100	$ 206,893	$ 166,573	$ 404,161	$ 427,913	$ 719,181	$ 711,252	$ 623,447
Long-lived assets			291,388				296,946				283,097		291,388	296,946
United States
Revenue and long-lived assets by geographic area
Revenue											256,926		519,361	491,818	403,001
Long-lived assets			186,543				190,997				186,960		186,543	190,997
Other Americas
Revenue and long-lived assets by geographic area
Revenue											41,777		67,809	68,628	55,120
Long-lived assets			29,743				31,558				29,065		29,743	31,558
Europe
Revenue and long-lived assets by geographic area
Revenue											91,847		118,566	137,071	143,931
Long-lived assets			75,102				73,744				67,072		75,102	73,744
Asia-Pacific
Revenue and long-lived assets by geographic area
Revenue											13,611		13,445	13,735	$ 21,395
Long-lived assets			$ 0				$ 647				$ 0		$ 0	$ 647

Repurchase of Common Stock (Details) - USD ($)		7 Months Ended
Repurchase of Common Stock (Details) - USD ($)	Aug. 17, 2016	Dec. 31, 2016	Oct. 07, 2015
Class of Stock [Line Items]
Treasury stock acquired, aggregate cost		$ 9,000,000
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		$ 41,000,000
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
Treasury stock acquired, average price (in dollars per share)		$ 21.90
Treasury stock acquired, aggregate cost		$ 6,000,000

Seven Months Ended December 31, 2015 Comparative Data (Unaudited) - Condensed Consolidated Statement of Income (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended										7 Months Ended		12 Months Ended
	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	May 31, 2015	May 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue	$ 176,642	$ 168,443	$ 184,187	$ 160,355	$ 194,786	$ 179,853	$ 174,686	$ 163,100	$ 206,893	$ 166,573	$ 404,161	$ 427,913	$ 719,181	$ 711,252	$ 623,447
Cost of revenue											274,298	292,718	494,911	506,281	432,695
Depreciation											12,859	12,005	21,262	20,238	17,809
Gross profit	52,076	50,056	52,000	42,809	56,925	51,274	44,966	38,734	59,039	41,994	117,004	123,190	203,008	184,733	172,943
Selling, general and administrative expenses											91,058	81,117	141,229	143,978	123,690
Research and engineering											1,577	1,431	2,523	2,521	2,995
Depreciation and amortization											6,340	6,503	11,212	13,048	10,620
Acquisition-related benefit, net											496	(959)	(1,453)	(5,167)	(2,657)
Income from operations	12,508	11,155	4,918	5,758	19,569	12,932	4,627	3,870	18,192	3,664	17,533	35,098	43,177	30,353	38,295
Interest expense, net												3,672
Income before provision for income taxes											15,481	31,426	38,415	25,731	35,103
Provision for income taxes											5,870	11,627	13,765	9,740	12,528
Net income											9,611	19,799	24,650	15,991	22,575
Less: Net (loss) attributable to non-controlling interests											43	(15)	(4)	(90)	57
Net income attributable to Mistras Group, Inc.	$ 7,270	$ 6,596	$ 2,764	$ 3,593	$ 11,425	$ 6,872	$ 2,171	$ 1,817	$ 10,427	$ 1,666	$ 9,568	$ 19,814	$ 24,654	$ 16,081	$ 22,518
Basic (in dollars per share)	$ 0.25	$ 0.23	$ 0.10	$ 0.12	$ 0.40	$ 0.24	$ 0.08	$ 0.06	$ 0.36	$ 0.06	$ 0.33	$ 0.69	$ 0.85	$ 0.56	$ 0.79
Diluted (in dollars per share)	$ 0.24	$ 0.22	$ 0.09	$ 0.12	$ 0.39	$ 0.23	$ 0.07	$ 0.06	$ 0.35	$ 0.06	$ 0.32	$ 0.67	$ 0.82	$ 0.54	$ 0.77
Basic (in shares)											28,989	28,810	28,856	28,613	28,365
Diluted (in shares)											30,125	29,676	29,891	29,590	29,324

Selected Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended										7 Months Ended		12 Months Ended
	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	May 31, 2016	May 31, 2015	May 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 176,642	$ 168,443	$ 184,187	$ 160,355	$ 194,786	$ 179,853	$ 174,686	$ 163,100	$ 206,893	$ 166,573	$ 404,161	$ 427,913	$ 719,181	$ 711,252	$ 623,447
Gross Profit	52,076	50,056	52,000	42,809	56,925	51,274	44,966	38,734	59,039	41,994	117,004	123,190	203,008	184,733	172,943
Income from operations	12,508	11,155	4,918	5,758	19,569	12,932	4,627	3,870	18,192	3,664	17,533	35,098	43,177	30,353	38,295
Net income attributable to Mistras Group, Inc.	$ 7,270	$ 6,596	$ 2,764	$ 3,593	$ 11,425	$ 6,872	$ 2,171	$ 1,817	$ 10,427	$ 1,666	$ 9,568	$ 19,814	$ 24,654	$ 16,081	$ 22,518
Earnings per common share:
Basic (in dollars per share)	$ 0.25	$ 0.23	$ 0.10	$ 0.12	$ 0.40	$ 0.24	$ 0.08	$ 0.06	$ 0.36	$ 0.06	$ 0.33	$ 0.69	$ 0.85	$ 0.56	$ 0.79
Diluted (in dollars per share)	$ 0.24	$ 0.22	$ 0.09	$ 0.12	$ 0.39	$ 0.23	$ 0.07	$ 0.06	$ 0.35	$ 0.06	$ 0.32	$ 0.67	$ 0.82	$ 0.54	$ 0.77

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Subsequent Events (Details) $ in Millions	2 Months Ended	7 Months Ended
Subsequent Events (Details) $ in Millions	Mar. 15, 2017 USD ($) Entity	Dec. 31, 2016
Subsequent Event [Line Items]
Period over which potential acquisition-related contingent consideration would be payable		2 years 10 months
Subsequent Event \| NDT Services \| United States
Subsequent Event [Line Items]
Number of entities acquired \| Entity	1
Cash paid	$ 4.5
Business combinations, deferred purchase price	1.5
Potential acquisition-related contingent consideration, high end of range	$ 2.0
Period over which potential acquisition-related contingent consideration would be payable	3 years