Document and Entity Information (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	May 31, 2013	Aug. 01, 2013	Nov. 30, 2012
Document and Entity Information
Entity Registrant Name	Mistras Group, Inc.
Entity Central Index Key	0001436126
Document Type	10-K
Document Period End Date	May 31, 2013
Amendment Flag	false
Current Fiscal Year End Date	--05-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 364.0
Entity Common Stock, Shares Outstanding		28,211,006
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	FY

Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	May 31, 2013	May 31, 2012
Current Assets
Cash and cash equivalents	$ 7,802	$ 8,410
Accounts receivable, net	108,554	104,515
Inventories	12,504	12,492
Deferred income taxes	2,621	1,885
Prepaid expenses and other current assets	8,156	6,321
Total current assets	139,637	133,623
Property, plant and equipment, net	68,419	63,527
Intangible assets, net	52,428	34,469
Goodwill	115,270	96,819
Other assets	906	1,378
Total assets	376,660	329,816
Current Liabilities
Accounts payable	8,490	11,944
Accrued expenses and other current liabilities	47,839	39,334
Current portion of long-term debt	7,418	5,971
Current portion of capital lease obligations	6,766	5,951
Income taxes payable	1,703	1,119
Total current liabilities	72,216	64,319
Long-term debt, net of current portion	52,849	34,258
Obligations under capital leases, net of current portion	10,923	13,094
Deferred income taxes	11,614	4,901
Other long-term liabilities	18,778	19,996
Total liabilities	166,380	136,568
Commitments and contingencies
Equity
Preferred stock, 10,000,000 shares authorized
Common stock, $0.01 par value, 200,000,000 shares authorized, 28,210,862 and 28,025,507 shares issued and outstanding as of May 31, 2013 and May 31, 2012, respectively	282	280
Additional paid-in capital	195,241	188,443
Retained earnings	18,982	7,336
Accumulated other comprehensive loss	(4,452)	(3,047)
Total Mistras Group, Inc. stockholders' equity	210,053	193,012
Noncontrolling interests	227	236
Total equity	210,280	193,248
Total liabilities and equity	$ 376,660	$ 329,816

Consolidated Balance Sheets (Parenthetical) (USD $)	May 31, 2013	May 31, 2012
Consolidated Balance Sheets
Preferred stock, shares authorized	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	28,210,862	28,025,507
Common stock, shares outstanding	28,210,862	28,025,507

Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Revenues:
Services	$ 487,268	$ 394,035	$ 308,702
Products and systems	42,014	42,840	29,887
Total revenues	529,282	436,875	338,589
Cost of revenues:
Cost of services	346,769	271,676	209,512
Cost of products and systems sold	16,276	19,940	12,468
Depreciation related to services	16,963	14,929	12,576
Depreciation related to products and systems	903	640	630
Total cost of revenues	380,911	307,185	235,186
Gross profit	148,371	129,690	103,403
Selling, general and administrative expenses	101,792	83,098	65,983
Research and engineering	2,447	2,059	2,150
Depreciation and amortization	8,781	6,455	5,386
Acquisition-related expense, net	(2,141)	1,980
Goodwill impairment	9,938
Legal reserve			273
Income from operations	27,554	36,098	29,611
Other expenses
Interest expense	3,288	3,132	2,773
Gain on extinguishment of long-term debt		(671)
Income before provision for income taxes	24,266	33,637	26,838
Provision for income taxes	12,627	12,291	10,502
Net income	11,639	21,346	16,336
Net loss attributable to noncontrolling interests, net of taxes	7	7	95
Net income attributable to Mistras Group, Inc.	$ 11,646	$ 21,353	$ 16,431
Earnings per common share
Basic (in dollars per share)	$ 0.41	$ 0.77	$ 0.61
Diluted (in dollars per share)	$ 0.40	$ 0.74	$ 0.61
Weighted average common shares outstanding:
Basic (in shares)	28,141	27,839	26,724
Diluted (in shares)	29,106	28,685	26,933

Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Consolidated Statements of Comprehensive Income
Net income	$ 11,639	$ 21,346	$ 16,336
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	(1,407)	(3,361)	1,905
Comprehensive income	10,232	17,985	18,241
Comprehensive income attributable to noncontrolling interests	7	7	95
Foreign currency translation adjustments	2	11	(15)
Comprehensive income attributable to Mistras Group, Inc.	$ 10,241	$ 18,003	$ 18,321

Consolidated Statements of Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Total Mistras Group, Inc. Stockholders' Equity	Common Stock	Additional paid-in capital	Retained earnings (accumulated deficit)	Accumulated other comprehensive income (loss)	Noncontrolling Interest
Balance at May. 31, 2010	$ 130,554	$ 130,286	$ 267	$ 162,054	$ (30,448)	$ (1,587)	$ 268
Balance (in shares) at May. 31, 2010			26,663,000
Increase (Decrease) in Stockholders' Equity
Net income	16,336	16,431			16,431		(95)
Other comprehensive income (loss), net of tax	1,905	1,890				1,890	15
Issuance of common stock from secondary offering, net	14,682	14,682	10	14,672
Issuance of common stock from secondary offering, net (in shares)			990,000
Share-based payments	3,751	3,751		3,751
Share-based payments (in shares)			3,000
Excess tax benefit from share-based payment compensation	22	22		22
Exercise of stock options	95	95		95
Exercise of stock options (in shares)			11,000
Noncontrolling interest in subsidiary	141						141
Balance at May. 31, 2011	167,486	167,157	277	180,594	(14,017)	303	329
Balance (in shares) at May. 31, 2011			27,667,000
Increase (Decrease) in Stockholders' Equity
Net income	21,346	21,353			21,353		(7)
Other comprehensive income (loss), net of tax	(3,361)	(3,350)				(3,350)	(11)
Share-based payments	5,097	5,097		5,097
Share-based payments (in shares)			16,000
Net settlement on vesting of restricted stock units	(283)	(283)		(283)
Net settlement on vesting of restricted stock units (in shares)			36,000
Excess tax benefit from share-based payment compensation	554	554		554
Exercise of stock options	2,484	2,484	3	2,481
Exercise of stock options (in shares)			307,000
Noncontrolling interest in subsidiary	(75)						(75)
Balance at May. 31, 2012	193,248	193,012	280	188,443	7,336	(3,047)	236
Balance (in shares) at May. 31, 2012			28,026,000
Increase (Decrease) in Stockholders' Equity
Net income	11,639	11,646			11,646		(7)
Other comprehensive income (loss), net of tax	(1,407)	(1,405)				(1,405)	(2)
Share-based payments	6,285	6,285		6,285
Share-based payments (in shares)			15,000
Net settlement on vesting of restricted stock units	(809)	(809)	1	(810)
Net settlement on vesting of restricted stock units (in shares)			85,000
Excess tax benefit from share-based payment compensation	495	495		495
Exercise of stock options	829	829	1	828
Exercise of stock options (in shares)			85,000
Balance at May. 31, 2013	$ 210,280	$ 210,053	$ 282	$ 195,241	$ 18,982	$ (4,452)	$ 227
Balance (in shares) at May. 31, 2013			28,211,000

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
Consolidated Statements of Cash Flows (USD $)	May 31, 2013	May 31, 2012	May 31, 2011
Cash flows from operating activities
Net income	$ 11,639,000	$ 21,346,000	$ 16,336,000
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	26,647,000	22,024,000	18,592,000
Deferred income taxes	(1,732,000)	(984,000)	1,779,000
Provision for doubtful accounts	379,000	479,000	253,000
Loss on extinguishment of long-term debt		(671,000)
(Gain) loss on sale of assets	(35,000)	(90,000)	21,000
Amortization of deferred financing costs	125,000	147,000	169,000
Share-based compensation expense	6,285,000	5,097,000	3,751,000
Goodwill impairment	9,938,000
Fair value adjustments to contingent consideration liabilities	(3,727,000)	174,000
Interest rate swap			(210,000)
Foreign currency loss (gain)	3,000	(508,000)	(335,000)
Changes in operating assets and liabilities, net of effect of acquisitions
Accounts receivable	4,772,000	(18,030,000)	(22,664,000)
Inventories	525,000	(1,708,000)	(77,000)
Prepaid expenses and other current assets	(1,042,000)	(1,503,000)
Other assets	462,000	(8,000)	47,000
Accounts payable	(5,478,000)	3,149,000	1,904,000
Accrued expenses and other liabilities	(3,832,000)	5,524,000	6,203,000
Income taxes payable	(1,426,000)	(3,036,000)	(515,000)
Net cash provided by operating activities	43,503,000	31,402,000	25,254,000
Cash flows from investing activities
Purchase of property, plant and equipment	(12,530,000)	(9,592,000)	(10,075,000)
Purchase of intangible assets	(993,000)	(813,000)	(520,000)
Acquisition of businesses, net of cash acquired	(33,122,000)	(29,216,000)	(26,195,000)
Proceeds from sale of equipment	1,166,000	2,109,000	312,000
Net cash used in investing activities	(45,479,000)	(37,512,000)	(36,478,000)
Cash flows from financing activities
Repayment of capital lease obligations	(6,972,000)	(6,984,000)	(6,230,000)
Repayment of long-term debt	(5,075,000)	(12,346,000)	(7,141,000)
Net (repayments) borrowings from former revolver		(3,850,000)	3,850,000
Net borrowings from current revolver	14,568,000	25,000,000
Net (repayments) proceeds from other short-term borrowings		(1,868,000)	45,000
Payment of financing costs		(623,000)
Proceeds from capital contribution from noncontrolling interests			21,000
Purchase of remaining noncontrolling interest in subsidiary		(75,000)
Net proceeds from issuance of common stock			14,682,000
Payment of contingent consideration for business acquisitions	(1,892,000)
Taxes paid related to net share settlement of equity awards	(809,000)	(283,000)
Excess tax benefit from share-based payment compensation	495,000	554,000	22,000
Proceeds from the exercise of stock options	829,000	2,484,000	95,000
Net cash provided by financing activities	1,144,000	2,009,000	5,344,000
Effect of exchange rate changes on cash and cash equivalents	224,000	1,632,000	722,000
Net change in cash and cash equivalents	(608,000)	(2,469,000)	(5,158,000)
Cash and cash equivalents:
Beginning of period	8,410,000	10,879,000	16,037,000
End of period	7,802,000	8,410,000	10,879,000
Supplemental disclosure of cash paid
Interest	3,144,000	2,749,000	2,783,000
Income taxes	15,639,000	14,871,000	9,257,000
Noncash investing and financing
Equipment acquired through capital lease obligations	3,886,000	9,504,000	6,403,000
Issuance of notes payable and other debt obligations primarily related to acquisitions	$ 7,715,000	$ 3,340,000	$ 10,407,000

Description of Business and Basis of Presentation	12 Months Ended
Description of Business and Basis of Presentation	May 31, 2013
Description of Business and Basis of Presentation
Description of Business and Basis of Presentation	1. 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, aerospace and defense, transportation, primary metals and metalworking, pharmaceuticals and food processing industries. *Principles of Consolidation* The accompanying consolidated financial statements include the accounts of Mistras Group, Inc. and its wholly and majority-owned subsidiaries. Where 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. All significant intercompany accounts and transactions have been eliminated in consolidation. Mistras Group, Inc.’s and its subsidiaries’ fiscal years end on May 31 except for the subsidiaries in the International segment, which end on April 30. Accordingly, the Company’s International segment subsidiaries are consolidated on a one-month lag. Therefore, in the quarter and year of acquisition, results of acquired subsidiaries in the International segment are 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. Management does not believe that any events occurred during the one-month lag period that would have a material effect on the Company’s consolidated financial statements as of or for any period presented. Reference to a fiscal year means the fiscal year ended May 31. *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. In fiscal 2013, the Company reclassified amounts related to interest accretion imputed on its acquisition-related contingent consideration liabilities from interest expense to acquisition-related expense, net, which is a component of income from operations. During fiscal 2012, the amount reclassified was $0.7 million. During fiscal 2011, there was no expense related to interest accretion imputed on our acquisition-related contingent consideration liabilities. See Note 8 — Acquisitions for further discussion with regards to acquisition related expense, net.

Summary of Significant Accounting Policies

12 Months Ended

May 31, 2013

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2. 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. 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, revenue is accrued for services that have been earned 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 generally 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 its, 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 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 and liabilities and disclosure of contingent assets and liabilities at the date of financial statements and the reported amounts of revenues and expenses during the reporting period. The accounting policies that the Company believes require more significant estimates and assumptions include: revenue recognition, valuations of accounts receivable, long lived assets, goodwill, and deferred tax assets and uncertain tax positions. The Company bases its estimates and assumption 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 generally written off when they are deemed uncollectible.

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.

Software Costs

Costs that are related to the conceptual formulation and design of licensed programs are expensed as research and engineering. For programs the Company licenses to customers, the Company capitalizes costs that are incurred between the date technological feasibility has been established and the date that the product becomes available for sale. Capitalized amounts are amortized using the straight-line basis over three years, which is the estimated life of the related software. The Company performs periodic reviews to ensure that unamortized program costs remain recoverable from future revenues. Costs to support or service these licensed programs are expensed as the costs are incurred.

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 the carrying value of 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), using a two-step approach, 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. 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, we would be required to recognize an impairment loss for that excess. We consider the income and market approaches to estimating the fair value of our reporting units, which requires significant judgment in evaluation of, among other things, economic and industry trends, estimated future cash flows, discount rates and other factors.

As of May 31, 2013, the carrying amount of our goodwill was approximately $115.3 million, of which approximately $40.8 million relates to our International segment. A significant portion of our international operations are concentrated in our Europe and Brazil reporting units. The economic environments in Europe and Brazil were difficult in 2013. As a result of a contraction in the Brazilian economy (specifically in the oil and gas industry), in the fourth quarter of fiscal 2013 we recognized goodwill impairment in our Brazil reporting unit of approximately $9.9 million. Significant deterioration in industry or economic trends, disruptions to our business, inability to effectively integrate acquired businesses, or other factors, may cause further impairment charges to goodwill in future periods.

Impairment of Long-lived Assets

The Company reviews the recoverability of its long-lived assets 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.

Shipping and Handling Costs

Shipping and handling costs are included in cost of revenues.

Taxes Collected from Customers

Taxes collected from customers and remitted to governmental authorities are presented in the consolidated statements of income on a net basis.

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 $1.7 million, $1.1 million and $0.8 million for fiscal 2013, 2012 and 2011, 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 assessment. 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 in all cases, is their local currency. 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 income for the period and included in accumulated other comprehensive 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 $0.1 million, ($0.5) million and ($0.3) million in fiscal 2013, 2012 and 2011, respectively.

Derivative Financial Instruments

The Company recognizes its derivatives as either assets or liabilities, measures those instruments at fair value and recognizes the changes in fair value of the derivative in net income or other comprehensive income, as appropriate. Prior to fiscal 2013, the Company hedged a portion of its variable rate interest payments on debt using interest rate swap contracts to convert variable payments into fixed payments. The Company did not apply hedge accounting to their interest rate swap contracts. Changes in the fair value of these instruments were reported as a component of interest expense. As of May 31, 2013 and 2012, the Company had no outstanding interest rate swap contracts.

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.

The Company has one customer, BP p.l.c. (BP), which accounted for 11%, 16% and 18% of revenues for fiscal 2013, 2012 and 2011, respectively. Accounts receivable from this customer was approximately 9% of total accounts receivable, net, at May 31, 2013 and 2012, respectively. The relationship with BP is comprised of separate contracts for non-destructive testing and inspection services with multiple affiliated entities within the broad BP organization. These contracts are typically negotiated locally with the specific location, are of varying lengths, have different start and end dates and differ in terms of the scope of work and nature of services provided. Most contracts are based on time and materials.

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 Company measures the cost of employee services received in exchange for an award of equity instruments based upon the grant-date fair value of the award. The Company uses the “straight-line” attribution method for allocating compensation costs and recognizes the fair value of each stock option on a straight-line basis over the vesting period of the related awards.

The Company uses the Black-Scholes option-pricing model to estimate the fair value of the share-based payment awards as of the grant date. The Black-Scholes model, is complex and dependent upon key assumptions including expected term and the estimated volatility of the Company’s stock price. Since the Company’s initial public offering (IPO) on October 7, 2009, the expected term of the Company’s stock options is generally determined using the simplified method. Expected stock price volatility is typically based on the daily historical trading data for a period equal to the expected term. Because the Company’s historical trading data only dates back to the IPO, the Company has estimated expected volatility using an analysis of the stock price volatility of comparable peer companies. Prior to the Company’s IPO, the exercise price equaled the estimated fair market value of the Company’s common stock, as determined by its board of directors. Since the Company’s IPO, the exercise price of stock option grants is determined using the closing market price of the Company’s common stock on the date of grant.

The following assumptions were used in valuing the options granted in fiscal years 2012 and 2011 (in fiscal 2013, no stock options were granted):

	For the years ended May 31,
	2012		2011

Dividend yield	0.0	%	0.0	%
Expected volatility	37	%	44	%
Risk-free interest rate	1.1	%	2.6	%
Expected term (years)	6.3		6.3

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 February 2013, the FASB issued Accounting Standard Update (ASU) 2013-02, Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income, which expands the disclosure requirements for amounts reclassified out of accumulated other comprehensive income. The update requires an entity to present either parenthetically on the face of the financial statement where net income is presented or in the notes to the financial statements, the effect of significant items reclassified in their entirety from accumulated other comprehensive income and identification of the respective line items effecting net income for instances when reclassification is required under GAAP. For items that are not required by GAAP to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures as required by GAAP. The update does not change the current requirements for reporting net income or other comprehensive income in financial statements and is effective for annual and interim reporting periods beginning after December 15, 2012. The adoption of this pronouncement did not have a material impact on the Company’s consolidated financial statements.

In July 2012, the FASB issued ASU 2012-02, Intangibles — Goodwill and Other (Topic 350): Testing Indefinite-Lived Intangible Assets for Impairment, that is intended to reduce the cost and complexity of the impairment test for indefinite-lived intangible assets by providing an entity with the option to first assess qualitatively whether it is necessary to perform the quantitative impairment test that is currently in place. An entity would not be required to quantitatively calculate the fair value of an indefinite-lived intangible asset unless the entity determines that it is more likely than not that its fair value is less than its carrying amount. ASU 2012-02 is effective for annual and interim impairment test beginning after September 15, 2012. The adoption of this pronouncement did not have a material impact on the Company’s consolidated financial statements.

In June 2011, the FASB issued ASU 2011-05, Comprehensive Income (Topic 220): Presentation of Comprehensive Income. ASU 2011-05 allows an entity to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. This guidance eliminates the option to present the components of other comprehensive income as part of the statement of equity. ASU 2011-05 does not change the items that must be reported in other comprehensive income, when an item of other comprehensive income must be reclassified to net income, or the Company’s option to present components of other comprehensive income either net of related tax effects or before related tax effects, nor does it affect how earnings per share is calculated or presented. Effective June 1, 2012, the Company adopted the provisions of this standard and such adoption did not have a material impact on the Company’s consolidated financial statements.

Earnings per Share

12 Months Ended

May 31, 2013

Earnings per Share

Earnings per Share

3. Earnings per Share

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

The following table sets forth the computations of basic and diluted earnings per share:

	For the year ended May 31,
	2013		2012		2011

Basic earnings per share
Numerator:
Net income attributable to Mistras Group, Inc.	$	11,646	$	21,353	$	16,431
Denominator
Weighted average common shares outstanding	28,141		27,839		26,724
Basic earnings per share	$	0.41	$	0.77	$	0.61

Diluted earnings per share:
Numerator:
Net income attributable to Mistras Group, Inc.	$	11,646	$	21,353	$	16,431
Denominator
Weighted average common shares outstanding	28,141		27,839		26,724
Dilutive effect of stock options outstanding	804		737		173
Dilutive effect of restricted stock units outstanding	161		109		36
	29,106		28,685		26,933
Diluted earnings per share	$	0.40	$	0.74	$	0.61

The following potential common shares related to options outstanding under the Company’s stock option plans were excluded from the computation of diluted earnings per share, as the effect would have been anti-dilutive:

	For the year ended May 31,
	2013	2012	2011

Potential common stock attributable to stock options outstanding	5	5	2,154

Accounts Receivable, net

12 Months Ended

May 31, 2013

Accounts Receivable, net

Accounts Receivable, net

4. Accounts Receivable, net

Accounts receivable consist of the following:

	May 31,
	2013			2012

Trade accounts receivable	$	110,438		$	106,821
Allowance for doubtful accounts	(1,884		)	(2,306		)
Accounts receivable, net	$	108,554		$	104,515

The Company had $8.1 million and $4.0 million of unbilled revenues accrued for fiscal 2013 and 2012, respectively. Unbilled revenues for fiscal 2013 are expected to be billed in the first quarter fiscal 2014.

Inventories

12 Months Ended

May 31, 2013

Inventories

Inventories

5. Inventories

Inventories consist of the following:

	May 31,
	2013		2012

Raw materials	$	3,332	$	3,054
Work in progress	2,310		2,232
Finished goods	4,355		4,287
Services-related consumable supplies	2,507		2,919
Inventory	$	12,504	$	12,492

Property, Plant and Equipment, net

12 Months Ended

May 31, 2013

Property, Plant and Equipment, net

Property, Plant and Equipment, net

6. Property, Plant and Equipment, net

Property, plant and equipment consist of the following:

	Useful Life	May 31,
	(Years)	2013			2012

Land		$	1,943		$	1,892
Building and improvements	30-40	20,973			16,950
Office furniture and equipment	5-8	7,244			6,760
Machinery and equipment	5-7	119,862			105,096

		150,022			130,698
Accumulated depreciation and amortization		(81,603		)	(67,171		)
Property, plant and equipment, net		$	68,419		$	63,527

Depreciation expense was approximately $18.9 million, $16.4 million and $13.5 million for the years ended May 31, 2013, 2012 and 2011, respectively.

Goodwill

12 Months Ended

May 31, 2013

Goodwill

Goodwill

7. Goodwill

The changes in the carrying amount of goodwill are as follows:

	Services			International			Products			Total

Balance at May 31, 2012	$	58,746		$	24,481		$	13,592		$	96,819
Goodwill acquired during the year	2,126			25,884			—			28,010
Adjustments to preliminary purchase price allocations	516			780			(395		)	901
Goodwill impairment	—			(9,938		)	—			(9,938		)
Foreign currency translation	(103		)	(419		)	—			(522		)
Balance at May 31, 2013	$	61,285		$	40,788		$	13,197		$	115,270

In the fourth quarter of fiscal 2013, as a result of a contraction in the Brazil economy, the Company experienced reduced demand for inspection services and a decline in recent and projected operating results. As a result of the completion of step one of the impairment analysis, the Company concluded that, as of March 1, 2013, the fair value of the Brazil reporting unit was below its respective carrying value and the step two analysis was performed. The Company recorded a goodwill impairment charge in the amount of $9.9 million related to Brazil which is reflected in the International segment in fiscal 2013.

Acquisitions

12 Months Ended

May 31, 2013

Acquisitions

Acquisitions

8. Acquisitions

During fiscal 2013, the Company completed the acquisition of three asset protection companies specializing in destructive and non-destructive services and inspection, and in-house component inspection. Two of these companies are intended to complement the service offerings within the International segment and to expand Mistras’ footprint in Europe. The other company, located in Canada, is intended to complement the service offerings within the Services segment. In these acquisitions, the Company acquired 100% of the common stock of each acquiree in exchange for an aggregate of approximately $35.0 million in cash and $7.7 million in notes payable over three years and accounted for such transactions in accordance with the acquisition method of accounting for business combinations. In addition to the cash and debt consideration related to these acquisitions, the Company accrued a liability of approximately $8.3 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 over the next five years of operations. The total potential contingent consideration for these acquisitions ranges from zero to $14.4 million as of May 31, 2013.

Assets and liabilities of the acquired businesses were included in the consolidated balance sheets as of May 31, 2013 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 results of operations of each of the acquisitions completed in fiscal 2013 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 at the date of acquisition for fiscal 2013 and 2012 acquisitions:

	2013			2012

Number of entities	3			11

Consideration transferred:
Cash paid	$	34,968		$	30,453
Subordinated notes issued	7,715			3,348
Contingent consideration	8,330			10,625

Consideration transferred	$	51,013		$	44,426

Current liabilities acquired	761			(5,773		)
Debt and other long-term liabilities	(4,540		)	(9,106		)
Property, plant and equipment	8,945			14,260
Deferred tax liability	(7,654		)	(1,746		)
Intangibles	25,491			11,934
Goodwill	28,010			34,857
Net assets acquired	$	51,013		$	44,426

The amortization period for intangible assets acquired in fiscal 2013 ranges from two to twelve years. The Company recorded approximately $28.0 million of goodwill in connection with its fiscal 2013 acquisitions, reflecting the strategic fit and revenue and earnings growth potential of these businesses. For acquisitions completed prior to fiscal 2012, substantially all of the goodwill recognized is expected to be deductible for tax purposes. However, the goodwill recorded in fiscal 2013 and 2012 relates primarily to the acquisition of the common stock of the acquiree, which is generally not deductible for tax purposes.

Revenue included in the consolidated statement of operations for fiscal 2013 from these acquisitions for the period subsequent to the closing of each transaction was approximately $44.5 million. Aggregate income from operations included in the consolidated statement of operations for fiscal 2013 from these acquisitions for the period subsequent to the closing of each transaction was approximately $0.5 million.

The unaudited pro forma information for the periods set forth below gives effect to the fiscal 2013 acquisitions as if they had occurred at the beginning of each period presented. The pro forma information is presented for informational purposes only and is not necessarily indicative of the results of operations that actually would have been achieved had the acquisitions been consummated as of that time (unaudited, in thousands):

	For the years ended May 31,
	2013		2012
Revenues	$	563,651	$	541,437

Income from operations	$	29,280	$	34,557

In the course of its acquisition activity, the Company incurs costs in connection with due diligence, professional fees, and other expenses. Additionally, the Company adjusts the fair value of certain acquisition-related contingent consideration liabilities on a quarterly basis. These amounts are recorded as acquisition-related expense, net, on the consolidated statements of income and were as follows for fiscal 2013 and 2012:

	For the years ended May 31,
	2013			2012
Due diligence, professional fees and other transaction costs	$	1,586		$	1,806
Adjustments to fair value of contingent consideration liabilities		(3,727	)		174
Acquisition-related expense, net	$	(2,141	)	$	1,980

The Company’s contingent consideration liabilities are recorded on the balance sheet in accrued expenses and other liabilities. Acquisition-related expense, net for the Company’s fiscal 2011 acquisition activity was insignificant.

Intangible Assets

12 Months Ended

May 31, 2013

Intangible Assets

Intangible Assets

9. Intangible Assets

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

		May 31,
		2013							2012

	Useful Life (Years)	Gross Amount		Accumulated Amortization			Net Carrying		Gross Amount		Accumulated Amortization			Net Carrying

Customer relationships	5-7	$	69,901	$	(27,422	)	$	42,479	$	45,050	$	(21,642	)	$	23,408
Software/Technology	3-15	14,336		(7,629		)	6,707		13,177		(6,691		)	6,486
Covenants not to compete	2-5	8,069		(7,523		)	546		7,969		(7,167		)	802
Other	2-5	5,932		(3,236		)	2,696		6,177		(2,404		)	3,773
Total		$	98,238	$	(45,810	)	$	52,428	$	72,373	$	(37,904	)	$	34,469

Amortization expense for the years ended May 31, 2013, 2012 and 2011 was approximately $7.7 million, $5.6 million and $5.0 million, respectively, including amortization of software/technology for the years ended May 31, 2013, 2012 and 2011 of $0.6 million, $0.3 million and $0.4 million, respectively.

Amortization expense in each of the five years and thereafter subsequent to May 31, 2013 related to the Company’s intangible assets is expected to be as follows:

	Expected Amortization Expense

2014	$	8,660
2015	8,375
2016	7,037
2017	5,335
2018	4,207
Thereafter	18,814
Total	$	52,428

Accrued Expenses and Other Current Liabilities

12 Months Ended

May 31, 2013

Accrued Expenses and Other Current Liabilities

Accrued Expenses and Other Current Liabilities

10. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:

	May 31,
	2013		2012

Accrued salaries, wages and related employee benefits	$	23,662	$	17,195
Contingent consideration	5,144		2,371
Accrued worker compensation and health benefits	3,667		3,678
Deferred revenues	2,623		5,390
Other accrued expenses	12,743		10,700
Total accrued expenses and other liabilities	$	47,839	$	39,334

Long-Term Debt

12 Months Ended

May 31, 2013

Long-Term Debt

Long-Term Debt

11. Long-Term Debt

Long-term debt consists of the following:

	May 31,
	2013			2012

Senior credit facility	$	39,567		$	25,000
Notes payable	15,740			12,532
Other	4,960			2,697
Total debt	60,267			40,229
Less: Current maturities	(7,418		)	(5,971		)
Long-term debt, net of current maturities	$	52,849		$	34,258

Senior Credit Facility

In December 2011, the Company entered into a Third Amended and Restated Credit Agreement (Credit Agreement) with Bank of America, N.A., as agent for the lenders and a lender, and JPMorgan Chase Bank, N.A., Keybank National Association and TD Bank, N.A., as lenders. The Credit Agreement provides the Company with a $125.0 million revolving line of credit, which, under certain circumstances, can be increased to $150.0 million. The Credit Agreement has a maturity date of December 20, 2016. The Company may borrow up to $30.0 million in non-U.S. Dollar currencies and use up to $10.0 million of the credit limit for the issuance of letters of credit. In December 2011, outstanding borrowings under the former credit agreement were repaid in full using proceeds from the Credit Agreement. As of May 31, 2013, there were outstanding borrowings of $39.6 million and a total of $3.3 million of outstanding letters of credit under the current revolving credit facility.

Loans under the Credit Agreement bear interest at LIBOR plus an applicable LIBOR margin ranging from 1% to 2%, or a base rate less a margin of 0.25% to 1.25%, at the option of the Company, or 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 2.5 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 if the Funded Debt Leverage Ratio exceeds 3.0 to 1. 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 less than 3.0 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 its 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.

During the year ended May 31, 2012, the Company capitalized approximately $0.6 million of costs related to the new credit agreement and expensed approximately $0.1 million of deferred financing costs related to its former credit facility. Also during the year, the Company recorded a $0.8 million gain related to the early extinguishment of debt assumed in an acquisition. The accelerated amounts expensed and gain on early extinguishment, net is classified as gain on extinguishment of long-term debt in the consolidated statements of income.

Notes Payable and Other Debt

In connection with acquisitions through fiscal 2013, the Company issued subordinated notes payable to the sellers. The maturity of these notes range from three to five years from the date of acquisition with stated interest rates ranging from 0% to 4%. The Company has discounted these obligations to reflect a 2% to 4% market interest. Unamortized discount on the notes was de minimus as of May 31, 2013 and approximately $0.1 million as of May 31, 2012. Amortization is recorded as interest expense in the consolidated statements of operations.

Scheduled principal payments due under all borrowing agreements in each of the five years and thereafter subsequent to May 31, 2013 are as follows:

2014	$	7,418
2015	7,986
2016	4,012
2017	40,399
2018	130
Thereafter	322
Total	$	60,267

Obligations under Capital Leases

12 Months Ended

May 31, 2013

Obligations under Capital Leases

Obligations under Capital Leases

12. Obligations under Capital Leases

The Company leases certain office space, including its headquarters, and service equipment under capital leases, requiring monthly payments ranging from less than $1 thousand to $72 thousand, including effective interest rates that range from approximately 3% to 9% expiring through May 2019. The net book value of assets under capital lease obligations was $16.1 million and $5.9 million at May 31, 2013 and 2012, respectively.

Scheduled future minimum lease payments subsequent to May 31, 2013 are as follows:

2014	$	7,795
2015	5,598
2016	3,699
2017	1,571
2018	238
Thereafter	168
Total minimum lease payments	19,069
Less: amount representing interest	(1,380		)
Present value of minimum lease payments	17,689
Less: current portion of obligations under capital leases	(6,766		)
Obligations under capital leases, net of current portion	$	10,923

Commitments and Contingencies

12 Months Ended

May 31, 2013

Commitments and Contingencies

Commitments and Contingencies

13. 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 May 31, 2013 are as follows:

2014	$	3,708
2015	2,254
2016	1,628
2017	1,097
2018	738
Thereafter	1,202
Total	$	10,627

Total rent expense was $7.2 million, $5.4 million and $4.2 million for the years ended May 31, 2013, 2012 and 2011, respectively.

Litigation

The Company is subject to periodic lawsuits, investigations and claims that arise in the ordinary course of business. Although the Company cannot predict with certainty the ultimate resolution of lawsuits, investigations and claims asserted against it, 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 in such matters may be covered by insurance.

In January 2012, the Company received notice of a governmental investigation concerning our environmental incident which occurred in February 2011 outside on the premises of its Cudahy, California location. No human injury or property damage was reported or appears to have been caused as a result of this incident, while management cannot predict the ultimate outcome of this matter, based on its internal investigation to date, the Company does not believe the outcome will have a material effect on its financial condition or results of operations.

During fiscal 2013, the Company performed radiography work on the construction of a pipeline project in Georgia. The Company has received notice that the pipeline project owner contends that certain of the x-ray images the Company’s technicians prepared regarding the project did not meet the code quality interpretation standards required by API (American Petroleum Institute) 1103. The project owner is claiming damages as a result of the alleged quality defects of the Company’s x-ray images. This matter is in the early stages and no lawsuit has yet to be filed. At the present time, the Company is 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.

Acquisition-related contingencies

The Company is liable for contingent consideration in connection with certain of its acquisitions. As of May 31, 2013, total potential acquisition-related contingent consideration ranged from zero to $24.6 million and would be payable upon the achievement of specific performance metrics by certain of the acquired companies over the next four years of operations. See Note 8 - Acquisitions for further discussion of the Company’s acquisitions.

Fair Value Measurements

12 Months Ended

May 31, 2013

Fair Value Measurements

Fair Value Measurements

14. 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:

	May 31, 2013
	Level 1		Level 2		Level 3		Total

Liabilities:
Contingent consideration	$	—	$	—	$	15,438	$	15,438
Total Liabilities	$	—	$	—	$	15,438	$	15,438

	May 31, 2012
	Level 1		Level 2		Level 3		Total

Liabilities:
Contingent consideration	$	—	$	—	$	13,513	$	13,513
Total Liabilities	$	—	$	—	$	13,513	$	13,513

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.

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	May 31, 2013
Employee Benefit Plans
Employee Benefit Plans	15. 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 six 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 approximately $2.3 million, $2.1 million and $1.9 million for the years ended May 31, 2013, 2012 and 2011, 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 less than $0.1 million in each of the years ended May 31, 2013, 2012 and 2011. 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.

Income Taxes

12 Months Ended

May 31, 2013

Income Taxes

Income Taxes

16. Income Taxes

Income before provision for income taxes is as follows:

	For the year ended May 31,
	2013			2012		2011

Income before provision for income taxes from:
U.S. operations	$	29,573		$	27,951	$	22,422
Foreign operations	(5,307		)	5,686		4,416
Earnings before income taxes	$	24,266		$	33,637	$	26,838

The provision for income taxes consists of the following:

	For the year ended May 31,
	2013			2012			2011

Current
Federal	$	9,035		$	8,792		$	5,921
States and local	1,673			1,762			1,589
Foreign	3,118			2,042			1,444
Reserve for uncertain tax positions	206			47			(231		)
Total current	14,032			12,643			8,723
Deferred
Federal	5			216			2,036
States and local	134			105			(359		)
Foreign	246			(359		)	85
Total deferred	385			(38		)	1,762
Net change in valuation allowance	(1,790		)	(314		)	17
Net deferred	(1,405		)	(352		)	1,779
Provision for income taxes	$	12,627		$	12,291		$	10,502

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

	For the year ended May 31,
	2013					2012					2011

Federal tax at statutory rate	$	8,493		35.0%		$	11,773		35.0%		$	9,393		35.0%
State taxes, net of federal benefit	1,174			4.8%		1,213			3.6%		799			2.9%
Foreign tax rate differentials	1,744			7.2%		(307		)	(0.9%	)	(16		)	(0.1%	)
Contingent consideration	(1,156		)	(4.8%	)	(370		)	(1.1%	)	—			0.0%
Permanent differences	498			2.1%		272			0.8%		585			2.2%
Goodwill impairment	3,478			14.3%		—			0.0%		—			0.0%
Other	186			0.8%		24			0.0%		(276		)	(1.0%	)
Change in valuation allowance	(1,790		)	(7.4%	)	(314		)	(0.9%	)	17			0.1%
Total provision for income taxes	$	12,627		52.0%		$	12,291		36.5%		$	10,502		39.1%

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

	May 31,
	2013			2012

Deferred income tax assets
Allowance for doubtful accounts	$	745		$	941
Inventory	637			490
Intangible assets	5,220			5,144
Accrued expenses	2,505			2,670
Net operating loss carryforward	3,314			3,757
Capital lease obligation	452			587
Share-based compensation	4,690			3,314
Other	37			65
Deferred income tax assets	17,600			16,968
Valuation allowance	(2,701		)	(4,491		)
Net deferred income tax assets	14,899			12,477
Deferred income tax liabilities
Property and equipment	(7,142		)	(7,675		)
Goodwill	(7,390		)	(4,907		)
Intangible assets	(9,277		)	(2,607		)
Other	(83		)	(304		)
Deferred income tax liabilities	(23,892		)	(15,493		)
Net deferred income taxes	$	(8,993	)	$	(3,016	)

Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to use the existing deferred tax assets. Evidence used includes information about the Company’s current financial position and results of operations for the current and preceding years, as well as available information about future years, the reversal of deferred tax liabilities and tax planning strategies. On the basis of this evaluation, as of May 31, 2013, a valuation allowance of $2.7 million has been recorded to recognize only the portion of the deferred tax asset that more likely than not will be realized.

As of May 31, 2013, the Company has available state net operating losses of approximately $1.5 million with expiration dates starting in fiscal 2015. In addition, the company has net operating losses in certain foreign jurisdictions of approximately $10.0 million some of which have unlimited life and others expire beginning in fiscal 2019.

The following table summarizes the changes in the Company’s gross unrecognized tax benefits, excluding interest and penalties:

	For the year ended May 31,
	2013			2012			2011
Balance at June 1	$	971		$	375		$	502
Additions for tax positions related to the current fiscal year	31			24			31
Additions for tax positions related to prior years	93			44			54
Decreases for tax positions related to prior years	—			(22		)	(119		)
Current year acquisitions	—			561			—
Impact of foreign exchange fluctuation	(24		)	—			—
Settlements	(4		)	—			—
Reductions related to the expiration of statutes of limitations	(6		)	(11		)	(93		)
Balance at May 31	$	1,061		$	971		$	375

The Company has recorded the unrecognized tax benefits in other long-term liabilities in the consolidated balance sheets as of May 31, 2013, 2012 and 2011. As of May 31, 2013, 2012 and 2011, there were approximately $1.4 million, $1.2 million and $0.4 million of unrecognized tax benefits, respectively, including penalties and interest that if recognized would favorably affect the effective tax rate. Interest and penalties related to unrecognized tax benefits are recorded in income tax expense and are not significant for the years ending May 31, 2013, 2012 and 2011. The Company anticipates a decrease to its unrecognized tax benefits of approximately $0.6 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, 2010 and generally is no longer subject to state, local or foreign income tax examinations by tax authorities for years ending before May 31, 2009.

The Company has not recognized U.S. tax expense on its undistributed international earnings or losses of its foreign subsidiaries since it intends to reinvest the earnings outside the United States. Net (loss) income of foreign subsidiaries was ($6.9) million and $4.3 million for fiscal 2013 and 2012, 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.

Capitalization

12 Months Ended

May 31, 2013

Capitalization

Capitalization

17. Capitalization

Common Stock

In May 2011, the Company completed a secondary offering of 3,754,061 shares of common stock at a price of $16.00 per share. The Company sold 989,660 shares and 2,764,401 shares were sold by a selling stockholder. The Company received net proceeds of approximately $14.7 million from the offering. The Company used the net proceeds for general corporate purposes including the reduction of outstanding indebtedness, acquisitions, capital expenditures and working capital.

Dividends on common stock will be paid when, and if, declared by the board of directors. Each holder of common stock is entitled to vote on all matters and is entitled to one vote for each share held.

Preferred Stock

Ten million shares of preferred stock are authorized; none are outstanding.

Equity Awards

In September 2009, the Company’s board of directors and shareholders adopted and approved the 2009 Long-Term Incentive Plan (the 2009 Plan), which became effective upon the closing of the IPO. Awards granted under the 2009 Plan may be in the form of stock options, restricted stock units and other forms of stock-based incentives, including stock appreciation rights and deferred stock rights. The term of each incentive and non-qualified stock option is ten years. Vesting generally occurs over a period of four years, the expense for which is recorded on a straight-line basis over the requisite service period. The 2009 Plan allows for the grant of awards of up to approximately 2,286,000 shares of common stock, of which approximately 1,449,000 shares were available for future grants as of May 31, 2013. Prior to the Company’s IPO in October 2009, the Company had two stock option plans: (i) the 1995 Incentive Stock Option and Restricted Stock Purchase Plan (the 1995 Plan), and (ii) the 2007 Stock Option Plan (the 2007 Plan). No additional awards may be granted from these two plans. As of May 31, 2013, there was an aggregate of approximately 2,463,000 stock options outstanding and approximately 555,000 unvested restricted stock units outstanding under the 2009 Plan, the 2007 Plan, and the 1995 Plan.

For the fiscal years ended May 31, 2013, 2012 and 2011, the Company recognized share-based compensation expense related to stock option awards of approximately $3.1 million, $3.2 million and $3.3 million, respectively. As of May 31, 2013, there was approximately $0.7 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards, which are expected to be recognized over a remaining weighted average period of 0.3 years. Cash proceeds from, and the aggregate intrinsic value of, stock options exercised during the years ended May 31, 2013, 2012 and 2011 were as follows:

	For the year ended May 31,
	2013		2012		2011

Cash proceeds from options exercised	$	829	$	2,484	$	95
Aggregate intrinsic value of options exercised	1,012		4,439		97

A summary of the stock option activity, weighted average exercise prices, options outstanding and exercisable as of May 31, 2013 is as follows (in thousands, except per share amounts):

	For the year ended May 31,
	2013				2012				2011
	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:	2,549		$	12.82	2,867		$	12.27	2,925		$	12.29
Granted	—		$	—	5		$	22.35	35		$	10.03
Exercised	(85	)	$	9.66	(307	)	$	8.07	(11	)	$	8.35
Expired or forfeited	—		$	—	(16	)	$	7.69	(82	)	$	12.77
Outstanding at end of year:	2,464		$	12.93	2,549		$	12.82	2,867		$	12.27

	For the year ended May 31,
	2013	2012		2011
Options exercisable at end of year	1,907	1,339		952
Weighted average grant date fair value (per share) of options granted during the period	—	$	8.46	$	4.47

			For the year ended May 31, 2013
			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-$13.08	360		5.5	$	9.70	343		$	9.69
$13.09-$22.35	2,104		6.3	$	13.49	1,564		$	13.47
	2,464					1,907

Aggregate Intrinsic Value	$	20,813				$	16,384

The Company also recognized approximately $2.9 million, $1.9 million and $0.5 million in share-based compensation expense related to restricted stock unit awards during the fiscal years ended May 31, 2013, 2012 and 2011, respectively. As of May 31, 2013, there were approximately $7.8 million of unrecognized compensation costs, net of estimated forfeitures, related to restricted stock unit awards, which are expected to be recognized over a remaining weighted average period of 2.5 years.

During the years ended May 31, 2013 and 2012, the Company granted approximately 13,000 and 9,000 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 $0.3 million and $0.2 million, respectively, which is included in the share-based compensation expense recorded during the years ended May 31, 2013 and 2012.

During the years ended May 31, 2013 and 2012, approximately 123,000 and 52,000 restricted stock units vested, respectively. The fair value of these units upon vesting was $1.9 million and $0.5 million, respectively. Upon vesting, restricted stock units are generally net share-settled to cover the required withholding tax and the remaining amount is converted into an equivalent number of shares of common stock. The restricted stock units that vested in fiscal 2013 and 2012 were net-share settled such that the Company withheld shares with value equivalent to the employees’ minimum statutory obligation for the applicable income and other employment taxes, and remitted the cash to the appropriate taxing authorities. The Company withheld approximately 37,000 and 16,000 shares in fiscal 2013 and 2012, respectively, based on the value of the restricted stock units on their vesting date as determined by the Company’s closing stock price. Total payments for the employees’ tax obligations to the taxing authorities were $0.8 million and $0.3 million and are reflected as a financing activity within the consolidated statements of cash flows. These net-share settlements had the effect of share repurchases by the Company as they reduced and retired the number of shares that would have otherwise been issued as a result of the vesting and did not represent an expense to the Company.

Related Party Transactions	12 Months Ended
Related Party Transactions	May 31, 2013
Related Party Transactions
Related Party Transactions	18. Related Party Transactions The Company leases its headquarters under a capital lease from a shareholder and officer of the Company requiring monthly payments through October 2014. Total rent payments made during fiscal 2013 were approximately $0.8 million. See Note 12 — Obligations under Capital Leases for further detail related to capital leases. The Company has a lease for office space located in France, which is partly owned by a shareholder and officer, requiring monthly payments through January 2016. Total rent payments made during fiscal 2013 were approximately $0.2 million.

Segment Disclosure

12 Months Ended

May 31, 2013

Segment Disclosure

Segment Disclosure

19. Segment Disclosure

The Company’s three operating segments are:

· Services. This segment provides asset protection solutions primarily in North America with the largest concentration in the United States and a rapidly expanding Canadian services business, consisting primarily of non-destructive testing and inspection services that are used to evaluate the structural integrity and reliability of critical energy, industrial and public infrastructure.

· 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.

· International. This segment offers services, products and systems similar to those of the Company’s other segments to global markets, principally 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. South America consists primarily of the Company’s Brazil operation.

Costs incurred for general corporate services, including accounting, audit, legal, and certain offer 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 determined based on internal performance measures used by the Chief Executive Officer, who is the chief operating decision maker, to assess the performance of each business in a given period and to make decisions as to resource allocations. In connection with that assessment, the Chief Executive Officer may exclude matters such as charges for share-based compensation and certain other acquisition-related charges and balances, technology and product development costs, certain gains and losses from dispositions, and litigation settlements or other charges. Certain general and administrative costs such as human resources, information technology and training are allocated to the segments. Segment income from operations also 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 depreciation on the corporate office facilities and equipment, 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:

	For the year ended May 31,
	2013			2012			2011
Revenues
Services	$	380,851		$	349,793		$	283,139
International	126,840			59,466			36,798
Products and Systems	33,301			40,083			26,105
Corporate and eliminations	(11,710		)	(12,467		)	(7,453		)
	$	529,282		$	436,875		$	338,589

Revenues by operating segment include intercompany transactions, which are eliminated in Corporate and eliminations. The Services segment had sales to other operating segments of $4.9 million, $2.8 million and $1.4 million for fiscal 2013, 2012 and 2011, respectively. The International segment had sales to other operating segments of $0.6 million, $0.9 million and $0.3 million for fiscal 2013, 2012 and 2011, respectively. The Products and Systems segment had sales to other operating segments of $6.0 million, $9.1 million and $4.4 million for fiscal 2013, 2012 and 2011, respectively.

	For the year ended May 31,
	2013		2012			2011
Gross profit
Services	$	98,907	$	94,413		$	77,883
International	32,319		19,106			12,922
Products and Systems	16,947		18,578			13,239
Corporate and eliminations	198		(2,407		)	(641		)
	$	148,371	$	129,690		$	103,403

	For the year ended May 31,
	2013			2012			2011
Income (loss) from operations
Services	$	40,325		$	39,932		$	31,856
International	(8,246		)	3,262			3,539
Products and Systems	7,286			8,271			5,123
Corporate and eliminations	(11,811		)	(15,367		)	(10,907		)
	$	27,554		$	36,098		$	29,611

Income (loss) from operations by operating segment includes intercompany transactions, which are eliminated in Corporate and eliminations.

	For the year ended May 31,
	2013			2012		2011
Depreciation and amortization
Services	$	18,296		$	17,763	$	15,979
International	6,200			2,342		1,396
Products and Systems	2,229			1,831		1,083
Corporate and eliminations	(78		)	88		134
	$	26,647		$	22,024	$	18,592

	May 31,
	2013		2012
Intangible assets, net
Services	$	14,527	$	17,180
International	27,520		6,390
Products and Systems	9,600		10,095
Corporate and eliminations	781		804
	$	52,428	$	34,469

	May 31,
	2013		2012
Total assets
Services	$	200,326	$	204,209
International	138,108		82,579
Products and Systems	37,948		43,914
Corporate and eliminations	278		(886		)
	$	376,660	$	329,816

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

	For the year ended May 31,
	2013		2012		2011
Revenue
United States	$	347,423	$	336,081	$	277,585
Other Americas	55,379		40,337		25,338
Europe	106,416		42,820		25,192
Asia-Pacific	20,064		17,637		10,474
	$	529,282	$	436,875	$	338,589

	May 31,
Long-lived assets	2013		2012
United States	$	122,727	$	130,813
Other Americas	28,148		37,109
Europe	85,171		26,766
Asia-Pacific	71		127
	$	236,117	$	194,815

Selected Quarterly Financial Information (unaudited)

12 Months Ended

May 31, 2013

Selected Quarterly Financial Information (unaudited)

Selected Quarterly Financial Information (unaudited)

20. Selected Quarterly Financial Information (unaudited)

The following is a summary of the quarterly results of operations for the years ended May 31, 2013 and 2012:

Fiscal quarter ended	May 31, 2013			February 28, 2013			November 30, 2012		August 31, 2012		May 31, 2012		February 29, 2012		November 30, 2011		August 31, 2011

Revenues	$	144,505		$	133,661		$	137,729	$	113,387	$	127,090	$	104,118	$	114,220	$	91,447
Cost of revenues	101,254			94,736			91,529		75,526		85,252		70,574		75,263		60,527
Depreciation	4,708			4,719			4,295		4,144		4,367		3,960		3,742		3,500
Gross profit	38,543			34,206			41,905		33,717		37,471		29,584		35,215		27,420
Selling, general and administrative expenses	27,729			27,209			23,362		23,492		23,533		20,806		19,378		19,381
Research and engineering	646			754			530		517		290		578		602		589
Depreciation and amortization	2,246			2,473			2,167		1,895		1,668		1,805		1,503		1,479
Acquisition-related expense, net	(1,135		)	(1,212		)	99		107		971		973		36		—
Goodwill impairment	9,938			—			—		—		—		—		—		—
Income (loss) from operations	(881		)	4,982			15,747		7,706		11,009		5,422		13,696		5,971
Net income (loss) attributable to Mistras Group, Inc.	$	(4,549	)	$	2,751		$	9,163	$	4,281	$	7,132	$	3,037	$	7,956	$	3,228
Earnings per common share:
Basic	(0.16		)	0.10			0.33		0.15		0.25		0.11		0.29		0.12
Diluted	(0.16		)	0.11			0.32		0.15		0.25		0.11		0.28		0.11

Description of Business and Basis of Presentation (Policies)	12 Months Ended
	May 31, 2013
Description of Business and Basis of Presentation
Principles of Consolidation	*Principles of Consolidation* The accompanying consolidated financial statements include the accounts of Mistras Group, Inc. and its wholly and majority-owned subsidiaries. Where 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. All significant intercompany accounts and transactions have been eliminated in consolidation. Mistras Group, Inc.’s and its subsidiaries’ fiscal years end on May 31 except for the subsidiaries in the International segment, which end on April 30. Accordingly, the Company’s International segment subsidiaries are consolidated on a one-month lag. Therefore, in the quarter and year of acquisition, results of acquired subsidiaries in the International segment are 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. Management does not believe that any events occurred during the one-month lag period that would have a material effect on the Company’s consolidated financial statements as of or for any period presented. Reference to a fiscal year means the fiscal year ended May 31.
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. In fiscal 2013, the Company reclassified amounts related to interest accretion imputed on its acquisition-related contingent consideration liabilities from interest expense to acquisition-related expense, net, which is a component of income from operations. During fiscal 2012, the amount reclassified was $0.7 million. During fiscal 2011, there was no expense related to interest accretion imputed on our acquisition-related contingent consideration liabilities. See Note 8 — Acquisitions for further discussion with regards to acquisition related expense, net.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

May 31, 2013

Summary of Significant Accounting Policies

Revenue Recognition

Revenue Recognition

Services

Products and Systems

Use of Estimates

Use of Estimates

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

Inventories

Inventories

Software Costs

Software Costs

Property, Plant and Equipment

Property, Plant and Equipment

Goodwill

Goodwill

Impairment of Long-lived Assets

Impairment of Long-lived Assets

Shipping and Handling Costs

Shipping and Handling Costs

Shipping and handling costs are included in cost of revenues.

Taxes Collected from Customers

Taxes Collected from Customers

Taxes collected from customers and remitted to governmental authorities are presented in the consolidated statements of income on a net basis.

Research and Engineering

Research and Engineering

Research and product development costs are expensed as incurred.

Advertising, Promotions and Marketing

Advertising, Promotions and Marketing

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Foreign Currency Translation

Foreign Currency Translation

Derivative Financial Instruments

Derivative Financial Instruments

Concentrations of Credit Risk

Concentrations of Credit Risk

Self-Insurance

Self-Insurance

Share-based Compensation

Share-based Compensation

The following assumptions were used in valuing the options granted in fiscal years 2012 and 2011 (in fiscal 2013, no stock options were granted):

	For the years ended May 31,
	2012		2011

Dividend yield	0.0	%	0.0	%
Expected volatility	37	%	44	%
Risk-free interest rate	1.1	%	2.6	%
Expected term (years)	6.3		6.3

Income Taxes

Income Taxes

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

May 31, 2013

Summary of Significant Accounting Policies

Schedule of assumptions used in valuing the options granted

	For the years ended May 31,
	2012		2011

Dividend yield	0.0	%	0.0	%
Expected volatility	37	%	44	%
Risk-free interest rate	1.1	%	2.6	%
Expected term (years)	6.3		6.3

Earnings per Share (Tables)

12 Months Ended

May 31, 2013

Earnings per Share

Schedule of computations of basic and diluted earnings per share

	For the year ended May 31,
	2013		2012		2011

Basic earnings per share
Numerator:
Net income attributable to Mistras Group, Inc.	$	11,646	$	21,353	$	16,431
Denominator
Weighted average common shares outstanding	28,141		27,839		26,724
Basic earnings per share	$	0.41	$	0.77	$	0.61

Diluted earnings per share:
Numerator:
Net income attributable to Mistras Group, Inc.	$	11,646	$	21,353	$	16,431
Denominator
Weighted average common shares outstanding	28,141		27,839		26,724
Dilutive effect of stock options outstanding	804		737		173
Dilutive effect of restricted stock units outstanding	161		109		36
	29,106		28,685		26,933
Diluted earnings per share	$	0.40	$	0.74	$	0.61

Schedule of shares that were excluded from the computation of diluted earnings per share

	For the year ended May 31,
	2013	2012	2011

Potential common stock attributable to stock options outstanding	5	5	2,154

Accounts Receivable, net (Tables)

12 Months Ended

May 31, 2013

Accounts Receivable, net

Schedule of accounts receivable

	May 31,
	2013			2012

Trade accounts receivable	$	110,438		$	106,821
Allowance for doubtful accounts	(1,884		)	(2,306		)
Accounts receivable, net	$	108,554		$	104,515

Inventories (Tables)

12 Months Ended

May 31, 2013

Inventories

Schedule of inventories

	May 31,
	2013		2012

Raw materials	$	3,332	$	3,054
Work in progress	2,310		2,232
Finished goods	4,355		4,287
Services-related consumable supplies	2,507		2,919
Inventory	$	12,504	$	12,492

Property, Plant and Equipment, net (Tables)

12 Months Ended

May 31, 2013

Property, Plant and Equipment, net

Schedule of Property, plant and equipment

	Useful Life	May 31,
	(Years)	2013			2012

Land		$	1,943		$	1,892
Building and improvements	30-40	20,973			16,950
Office furniture and equipment	5-8	7,244			6,760
Machinery and equipment	5-7	119,862			105,096

		150,022			130,698
Accumulated depreciation and amortization		(81,603		)	(67,171		)
Property, plant and equipment, net		$	68,419		$	63,527

Goodwill (Tables)

12 Months Ended

May 31, 2013

Goodwill

Schedule of changes in carrying amount of goodwill

	Services			International			Products			Total

Balance at May 31, 2012	$	58,746		$	24,481		$	13,592		$	96,819
Goodwill acquired during the year	2,126			25,884			—			28,010
Adjustments to preliminary purchase price allocations	516			780			(395		)	901
Goodwill impairment	—			(9,938		)	—			(9,938		)
Foreign currency translation	(103		)	(419		)	—			(522		)
Balance at May 31, 2013	$	61,285		$	40,788		$	13,197		$	115,270

Acquisitions (Tables)

12 Months Ended

May 31, 2013

Acquisitions

Summary of estimated fair value of assets acquired and liabilities assumed at the date of acquisition

	2013			2012

Number of entities	3			11

Consideration transferred:
Cash paid	$	34,968		$	30,453
Subordinated notes issued	7,715			3,348
Contingent consideration	8,330			10,625

Consideration transferred	$	51,013		$	44,426

Current liabilities acquired	761			(5,773		)
Debt and other long-term liabilities	(4,540		)	(9,106		)
Property, plant and equipment	8,945			14,260
Deferred tax liability	(7,654		)	(1,746		)
Intangibles	25,491			11,934
Goodwill	28,010			34,857
Net assets acquired	$	51,013		$	44,426

Schedule of pro forma information of the results of operations

The pro forma information is presented for informational purposes only and is not necessarily indicative of the results of operations that actually would have been achieved had the acquisitions been consummated as of that time (unaudited, in thousands):

	For the years ended May 31,
	2013		2012
Revenues	$	563,651	$	541,437

Income from operations	$	29,280	$	34,557

Schedule of acquisition-related expense, net

	For the years ended May 31,
	2013			2012
Due diligence, professional fees and other transaction costs	$	1,586		$	1,806
Adjustments to fair value of contingent consideration liabilities		(3,727	)		174
Acquisition-related expense, net	$	(2,141	)	$	1,980

Intangible Assets (Tables)

12 Months Ended

May 31, 2013

Intangible Assets

Schedule of gross carrying amount and accumulated amortization of intangible assets

		May 31,
		2013							2012

	Useful Life (Years)	Gross Amount		Accumulated Amortization			Net Carrying		Gross Amount		Accumulated Amortization			Net Carrying

Customer relationships	5-7	$	69,901	$	(27,422	)	$	42,479	$	45,050	$	(21,642	)	$	23,408
Software/Technology	3-15	14,336		(7,629		)	6,707		13,177		(6,691		)	6,486
Covenants not to compete	2-5	8,069		(7,523		)	546		7,969		(7,167		)	802
Other	2-5	5,932		(3,236		)	2,696		6,177		(2,404		)	3,773
Total		$	98,238	$	(45,810	)	$	52,428	$	72,373	$	(37,904	)	$	34,469

Schedule of expected amortization expense of intangible assets

	Expected Amortization Expense

2014	$	8,660
2015	8,375
2016	7,037
2017	5,335
2018	4,207
Thereafter	18,814
Total	$	52,428

Accrued Expenses and Other Current Liabilities (Tables)

12 Months Ended

May 31, 2013

Accrued Expenses and Other Current Liabilities

Schedule of accrued expenses and other current liabilities

	May 31,
	2013		2012

Accrued salaries, wages and related employee benefits	$	23,662	$	17,195
Contingent consideration	5,144		2,371
Accrued worker compensation and health benefits	3,667		3,678
Deferred revenues	2,623		5,390
Other accrued expenses	12,743		10,700
Total accrued expenses and other liabilities	$	47,839	$	39,334

Long-Term Debt (Tables)

12 Months Ended

May 31, 2013

Long-Term Debt

Schedule of long-term debt

	May 31,
	2013			2012

Senior credit facility	$	39,567		$	25,000
Notes payable	15,740			12,532
Other	4,960			2,697
Total debt	60,267			40,229
Less: Current maturities	(7,418		)	(5,971		)
Long-term debt, net of current maturities	$	52,849		$	34,258

Schedule of principal payments due under all borrowing agreements

2014	$	7,418
2015	7,986
2016	4,012
2017	40,399
2018	130
Thereafter	322
Total	$	60,267

Obligations under Capital Leases (Tables)

12 Months Ended

May 31, 2013

Obligations under Capital Leases

Scheduled future minimum lease payments

2014	$	7,795
2015	5,598
2016	3,699
2017	1,571
2018	238
Thereafter	168
Total minimum lease payments	19,069
Less: amount representing interest	(1,380		)
Present value of minimum lease payments	17,689
Less: current portion of obligations under capital leases	(6,766		)
Obligations under capital leases, net of current portion	$	10,923

Commitments and Contingencies (Tables)

12 Months Ended

May 31, 2013

Commitments and Contingencies

Schedule of future minimum lease payments under noncancelable operating leases

2014	$	3,708
2015	2,254
2016	1,628
2017	1,097
2018	738
Thereafter	1,202
Total	$	10,627

Fair Value Measurements (Tables)

12 Months Ended

May 31, 2013

Fair Value Measurements

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

	May 31, 2013
	Level 1		Level 2		Level 3		Total

Liabilities:
Contingent consideration	$	—	$	—	$	15,438	$	15,438
Total Liabilities	$	—	$	—	$	15,438	$	15,438

	May 31, 2012
	Level 1		Level 2		Level 3		Total

Liabilities:
Contingent consideration	$	—	$	—	$	13,513	$	13,513
Total Liabilities	$	—	$	—	$	13,513	$	13,513

Income Taxes (Tables)

12 Months Ended

May 31, 2013

Income Taxes

Schedule of income before provision for income taxes

	For the year ended May 31,
	2013			2012		2011

Income before provision for income taxes from:
U.S. operations	$	29,573		$	27,951	$	22,422
Foreign operations	(5,307		)	5,686		4,416
Earnings before income taxes	$	24,266		$	33,637	$	26,838

Schedule of provision for income taxes

	For the year ended May 31,
	2013			2012			2011

Current
Federal	$	9,035		$	8,792		$	5,921
States and local	1,673			1,762			1,589
Foreign	3,118			2,042			1,444
Reserve for uncertain tax positions	206			47			(231		)
Total current	14,032			12,643			8,723
Deferred
Federal	5			216			2,036
States and local	134			105			(359		)
Foreign	246			(359		)	85
Total deferred	385			(38		)	1,762
Net change in valuation allowance	(1,790		)	(314		)	17
Net deferred	(1,405		)	(352		)	1,779
Provision for income taxes	$	12,627		$	12,291		$	10,502

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

	For the year ended May 31,
	2013					2012					2011

Federal tax at statutory rate	$	8,493		35.0%		$	11,773		35.0%		$	9,393		35.0%
State taxes, net of federal benefit	1,174			4.8%		1,213			3.6%		799			2.9%
Foreign tax rate differentials	1,744			7.2%		(307		)	(0.9%	)	(16		)	(0.1%	)
Contingent consideration	(1,156		)	(4.8%	)	(370		)	(1.1%	)	—			0.0%
Permanent differences	498			2.1%		272			0.8%		585			2.2%
Goodwill impairment	3,478			14.3%		—			0.0%		—			0.0%
Other	186			0.8%		24			0.0%		(276		)	(1.0%	)
Change in valuation allowance	(1,790		)	(7.4%	)	(314		)	(0.9%	)	17			0.1%
Total provision for income taxes	$	12,627		52.0%		$	12,291		36.5%		$	10,502		39.1%

Schedule of deferred income tax assets and liabilities

	May 31,
	2013			2012

Deferred income tax assets
Allowance for doubtful accounts	$	745		$	941
Inventory	637			490
Intangible assets	5,220			5,144
Accrued expenses	2,505			2,670
Net operating loss carryforward	3,314			3,757
Capital lease obligation	452			587
Share-based compensation	4,690			3,314
Other	37			65
Deferred income tax assets	17,600			16,968
Valuation allowance	(2,701		)	(4,491		)
Net deferred income tax assets	14,899			12,477
Deferred income tax liabilities
Property and equipment	(7,142		)	(7,675		)
Goodwill	(7,390		)	(4,907		)
Intangible assets	(9,277		)	(2,607		)
Other	(83		)	(304		)
Deferred income tax liabilities	(23,892		)	(15,493		)
Net deferred income taxes	$	(8,993	)	$	(3,016	)

Summary of changes in Company's gross unrecognized tax benefits, excluding interest and penalties

	For the year ended May 31,
	2013			2012			2011
Balance at June 1	$	971		$	375		$	502
Additions for tax positions related to the current fiscal year	31			24			31
Additions for tax positions related to prior years	93			44			54
Decreases for tax positions related to prior years	—			(22		)	(119		)
Current year acquisitions	—			561			—
Impact of foreign exchange fluctuation	(24		)	—			—
Settlements	(4		)	—			—
Reductions related to the expiration of statutes of limitations	(6		)	(11		)	(93		)
Balance at May 31	$	1,061		$	971		$	375

Capitalization (Tables)

12 Months Ended

May 31, 2013

Capitalization

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

	For the year ended May 31,
	2013		2012		2011

Cash proceeds from options exercised	$	829	$	2,484	$	95
Aggregate intrinsic value of options exercised	1,012		4,439		97

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 May 31, 2013 is as follows (in thousands, except per share amounts):

	For the year ended May 31,
	2013				2012				2011
	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:	2,549		$	12.82	2,867		$	12.27	2,925		$	12.29
Granted	—		$	—	5		$	22.35	35		$	10.03
Exercised	(85	)	$	9.66	(307	)	$	8.07	(11	)	$	8.35
Expired or forfeited	—		$	—	(16	)	$	7.69	(82	)	$	12.77
Outstanding at end of year:	2,464		$	12.93	2,549		$	12.82	2,867		$	12.27

	For the year ended May 31,
	2013	2012		2011
Options exercisable at end of year	1,907	1,339		952
Weighted average grant date fair value (per share) of options granted during the period	—	$	8.46	$	4.47

Schedule of information concerning outstanding and exercisable options

			For the year ended May 31, 2013
			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-$13.08	360		5.5	$	9.70	343		$	9.69
$13.09-$22.35	2,104		6.3	$	13.49	1,564		$	13.47
	2,464					1,907

Aggregate Intrinsic Value	$	20,813				$	16,384

Segment Disclosure (Tables)

12 Months Ended

May 31, 2013

Segment Disclosure

Schedule of financial information by segment

	For the year ended May 31,
	2013			2012			2011
Revenues
Services	$	380,851		$	349,793		$	283,139
International	126,840			59,466			36,798
Products and Systems	33,301			40,083			26,105
Corporate and eliminations	(11,710		)	(12,467		)	(7,453		)
	$	529,282		$	436,875		$	338,589

	For the year ended May 31,
	2013		2012			2011
Gross profit
Services	$	98,907	$	94,413		$	77,883
International	32,319		19,106			12,922
Products and Systems	16,947		18,578			13,239
Corporate and eliminations	198		(2,407		)	(641		)
	$	148,371	$	129,690		$	103,403

	For the year ended May 31,
	2013			2012			2011
Income (loss) from operations
Services	$	40,325		$	39,932		$	31,856
International	(8,246		)	3,262			3,539
Products and Systems	7,286			8,271			5,123
Corporate and eliminations	(11,811		)	(15,367		)	(10,907		)
	$	27,554		$	36,098		$	29,611

	For the year ended May 31,
	2013			2012		2011
Depreciation and amortization
Services	$	18,296		$	17,763	$	15,979
International	6,200			2,342		1,396
Products and Systems	2,229			1,831		1,083
Corporate and eliminations	(78		)	88		134
	$	26,647		$	22,024	$	18,592

	May 31,
	2013		2012
Intangible assets, net
Services	$	14,527	$	17,180
International	27,520		6,390
Products and Systems	9,600		10,095
Corporate and eliminations	781		804
	$	52,428	$	34,469

	May 31,
	2013		2012
Total assets
Services	$	200,326	$	204,209
International	138,108		82,579
Products and Systems	37,948		43,914
Corporate and eliminations	278		(886		)
	$	376,660	$	329,816

Schedule of revenue and long-lived assets by geographic area

	For the year ended May 31,
	2013		2012		2011
Revenue
United States	$	347,423	$	336,081	$	277,585
Other Americas	55,379		40,337		25,338
Europe	106,416		42,820		25,192
Asia-Pacific	20,064		17,637		10,474
	$	529,282	$	436,875	$	338,589

	May 31,
Long-lived assets	2013		2012
United States	$	122,727	$	130,813
Other Americas	28,148		37,109
Europe	85,171		26,766
Asia-Pacific	71		127
	$	236,117	$	194,815

Selected Quarterly Financial Information (unaudited) (Tables)

12 Months Ended

May 31, 2013

Selected Quarterly Financial Information (unaudited)

Summary of the quarterly results of operations

Fiscal quarter ended	May 31, 2013			February 28, 2013			November 30, 2012		August 31, 2012		May 31, 2012		February 29, 2012		November 30, 2011		August 31, 2011

Revenues	$	144,505		$	133,661		$	137,729	$	113,387	$	127,090	$	104,118	$	114,220	$	91,447
Cost of revenues	101,254			94,736			91,529		75,526		85,252		70,574		75,263		60,527
Depreciation	4,708			4,719			4,295		4,144		4,367		3,960		3,742		3,500
Gross profit	38,543			34,206			41,905		33,717		37,471		29,584		35,215		27,420
Selling, general and administrative expenses	27,729			27,209			23,362		23,492		23,533		20,806		19,378		19,381
Research and engineering	646			754			530		517		290		578		602		589
Depreciation and amortization	2,246			2,473			2,167		1,895		1,668		1,805		1,503		1,479
Acquisition-related expense, net	(1,135		)	(1,212		)	99		107		971		973		36		—
Goodwill impairment	9,938			—			—		—		—		—		—		—
Income (loss) from operations	(881		)	4,982			15,747		7,706		11,009		5,422		13,696		5,971
Net income (loss) attributable to Mistras Group, Inc.	$	(4,549	)	$	2,751		$	9,163	$	4,281	$	7,132	$	3,037	$	7,956	$	3,228
Earnings per common share:
Basic	(0.16		)	0.10			0.33		0.15		0.25		0.11		0.29		0.12
Diluted	(0.16		)	0.11			0.32		0.15		0.25		0.11		0.28		0.11

Description of Business and Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013 item	May 31, 2012	May 31, 2011
Principles of Consolidation
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	1
Reclassification
Interest accretion expense related to contingent consideration liabilities reclassified from interest expense to acquisition-related expense		$ 0.7	$ 0

Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Foreign Currency Translation
Foreign Currency Transaction (Gain) Loss	$ 100,000	$ (500,000)	$ (300,000)
Advertising, Promotions and Marketing
Advertising expense	1,700,000	1,100,000	800,000
Derivative Financial Instruments
Outstanding interest rate swap contracts	$ 0	$ 0
Software/Technology
Software Costs
Estimated useful Life	3 years
Software/Technology \| Maximum
Software Costs
Estimated useful Life	15 years

Summary of Significant Accounting Policies (Details 2) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Concentration of Credit Risk
Stock options granted (in shares)	0
Self-Insurance
Minimum Amount of workers compensation and health benefit claims for which third-party excess insurance coverage maintained	$ 0.3
Share-based Compensation
Dividend yield (as a percent)		0.00%	0.00%
Expected volatility (as a percent)		37.00%	44.00%
Risk-free interest rate (as a percent)		1.10%	2.60%
Expected term		6 years 3 months 18 days	6 years 3 months 18 days
Customer concentration risk
Concentration of Credit Risk
Number of customers	1
Revenues \| Customer concentration risk \| BP
Concentration of Credit Risk
Percentage of concentration risk	11.00%	16.00%	18.00%
Accounts receivable, net \| Customer concentration risk \| BP
Concentration of Credit Risk
Percentage of concentration risk	9.00%	9.00%

Summary of Significant Accounting Policies (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	May 31, 2013	May 31, 2013	May 31, 2012
Goodwill
Carrying value of goodwill	$ 115,270	$ 115,270	$ 96,819
Goodwill impairment	9,938	9,938
Brazil
Goodwill
Goodwill impairment	9,900
International
Goodwill
Carrying value of goodwill	40,788	40,788	24,481
Goodwill impairment		$ 9,938

Earnings per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2013	May 31, 2012	May 31, 2011
Numerator:
Net income attributable to Mistras Group, Inc.	$ (4,549)	$ 2,751	$ 9,163	$ 4,281	$ 7,132	$ 3,037	$ 7,956	$ 3,228	$ 11,646	$ 21,353	$ 16,431
Denominator:
Weighted average common shares outstanding									28,141	27,839	26,724
Basic earnings per share (in dollars per share)	$ (0.16)	$ 0.10	$ 0.33	$ 0.15	$ 0.25	$ 0.11	$ 0.29	$ 0.12	$ 0.41	$ 0.77	$ 0.61
Numerator:
Net income attributable to Mistras Group, Inc.	$ (4,549)	$ 2,751	$ 9,163	$ 4,281	$ 7,132	$ 3,037	$ 7,956	$ 3,228	$ 11,646	$ 21,353	$ 16,431
Denominator:
Weighted average common shares outstanding									28,141	27,839	26,724
Dilutive effect of stock options outstanding (in shares)									804	737	173
Dilutive effect of restricted stock units outstanding (in shares)									161	109	36
Weighted average common shares outstanding, diluted									29,106	28,685	26,933
Diluted earnings per share (in dollars per share)	$ (0.16)	$ 0.11	$ 0.32	$ 0.15	$ 0.25	$ 0.11	$ 0.28	$ 0.11	$ 0.40	$ 0.74	$ 0.61
Potential common stock attributable to stock options outstanding
Earnings per Share
Total shares									5	5	2,154

Accounts Receivable, net (Details) (USD $)	May 31, 2013	May 31, 2012
Accounts Receivable, net
Trade accounts receivable	$ 110,438,000	$ 106,821,000
Allowance for doubtful accounts	(1,884,000)	(2,306,000)
Accounts receivable, net	108,554,000	104,515,000
Accrued unbilled revenues	$ 8,100,000	$ 4,000,000

Inventories (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2013	May 31, 2012
Inventories
Raw materials	$ 3,332	$ 3,054
Work in process	2,310	2,232
Finished goods	4,355	4,287
Services-related consumable supplies	2,507	2,919
Inventory	$ 12,504	$ 12,492

Property, Plant and Equipment, net (Details) (USD $)	12 Months Ended
Property, Plant and Equipment, net (Details) (USD $)	May 31, 2013	May 31, 2012	May 31, 2011
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 150,022,000	$ 130,698,000
Accumulated depreciation and amortization	(81,603,000)	(67,171,000)
Property, plant and equipment, net	68,419,000	63,527,000
Depreciation expense	18,900,000	16,400,000	13,500,000
Land
Property, Plant and Equipment, net
Property, plant and equipment, gross	1,943,000	1,892,000
Building and improvements
Property, Plant and Equipment, net
Property, plant and equipment, gross	20,973,000	16,950,000
Building and improvements \| Minimum
Property, Plant and Equipment, net
Useful Life	30 years
Building and improvements \| Maximum
Property, Plant and Equipment, net
Useful Life	40 years
Office furniture and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross	7,244,000	6,760,000
Office furniture and equipment \| Minimum
Property, Plant and Equipment, net
Useful Life	5 years
Office furniture and equipment \| Maximum
Property, Plant and Equipment, net
Useful Life	8 years
Machinery and equipment
Property, Plant and Equipment, net
Property, plant and equipment, gross	$ 119,862,000	$ 105,096,000
Machinery and equipment \| Minimum
Property, Plant and Equipment, net
Useful Life	5 years
Machinery and equipment \| Maximum
Property, Plant and Equipment, net
Useful Life	7 years

Goodwill (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	May 31, 2013	May 31, 2013
Changes in the carrying amount of goodwill
Balance at the beginning of the period		$ 96,819
Goodwill acquired during the year		28,010
Adjustments to preliminary purchase price allocations		901
Goodwill impairment	(9,938)	(9,938)
Foreign currency translation		(522)
Balance at the end of the period	115,270	115,270
Services
Changes in the carrying amount of goodwill
Balance at the beginning of the period		58,746
Goodwill acquired during the year		2,126
Adjustments to preliminary purchase price allocations		516
Foreign currency translation		(103)
Balance at the end of the period	61,285	61,285
International
Changes in the carrying amount of goodwill
Balance at the beginning of the period		24,481
Goodwill acquired during the year		25,884
Adjustments to preliminary purchase price allocations		780
Goodwill impairment		(9,938)
Foreign currency translation		(419)
Balance at the end of the period	40,788	40,788
Products and Systems
Changes in the carrying amount of goodwill
Balance at the beginning of the period		13,592
Adjustments to preliminary purchase price allocations		(395)
Balance at the end of the period	$ 13,197	$ 13,197

Acquisitions (Details) (USD $)	3 Months Ended							12 Months Ended
Acquisitions (Details) (USD $)	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	May 31, 2013	May 31, 2012
Consideration transferred
Contingent consideration	$ 5,144,000				$ 2,371,000			$ 5,144,000	$ 2,371,000
Goodwill								28,010,000
Acquisition-related expense, net
Fair value adjustments to contingent consideration liabilities								(3,727,000)	174,000
Acquisition-related expense, net	(1,135,000)	(1,212,000)	99,000	107,000	971,000	973,000	36,000	(2,141,000)	1,980,000
International
Consideration transferred
Goodwill								25,884,000
Services
Consideration transferred
Goodwill								2,126,000
Fiscal 2013 acquisitions
Estimated fair value of the assets acquired and liabilities assumed
Number of entities								3
Consideration transferred
Cash paid								34,968,000
Subordinated notes issued								7,715,000
Contingent consideration	8,330,000							8,330,000
Consideration transferred								51,013,000
Current liabilities acquired	761,000							761,000
Debt and other long-term liabilities	(4,540,000)							(4,540,000)
Property, plant and equipment	8,945,000							8,945,000
Deferred tax liability	(7,654,000)							(7,654,000)
Intangibles	25,491,000							25,491,000
Goodwill								28,010,000
Net assets acquired	51,013,000							51,013,000
Revenue and income from operations included in the consolidated statement of operations
Revenues								44,500,000
Aggregate income from operations								500,000
Pro forma information of the results of operations
Revenues								563,651,000	541,437,000
Income from operations								29,280,000	34,557,000
Acquisition-related expense, net
Due diligence, professional fees and other transaction costs	1,586,000							1,586,000
Fair value adjustments to contingent consideration liabilities								(3,727,000)
Acquisition-related expense, net								(2,141,000)
Fiscal 2013 acquisitions \| International
Estimated fair value of the assets acquired and liabilities assumed
Number of entities								2
Fiscal 2013 acquisitions \| Minimum
Consideration transferred
Amortization period of intangible assets acquired								2 years
Fiscal 2013 acquisitions \| Maximum
Consideration transferred
Amortization period of intangible assets acquired								12 years
Fiscal 2012 acquisitions
Estimated fair value of the assets acquired and liabilities assumed
Number of entities									11
Consideration transferred
Cash paid									30,453,000
Subordinated notes issued									3,348,000
Contingent consideration					10,625,000				10,625,000
Consideration transferred									44,426,000
Current liabilities acquired					(5,773,000)				(5,773,000)
Debt and other long-term liabilities					(9,106,000)				(9,106,000)
Property, plant and equipment					14,260,000				14,260,000
Deferred tax liability					(1,746,000)				(1,746,000)
Intangibles					11,934,000				11,934,000
Goodwill									34,857,000
Net assets acquired					44,426,000				44,426,000
Acquisition-related expense, net
Due diligence, professional fees and other transaction costs					1,806,000				1,806,000
Fair value adjustments to contingent consideration liabilities									174,000
Acquisition-related expense, net									1,980,000
Series of Individually Immaterial Business Acquisitions
Acquisitions
Percentage of common stock acquired	100.00%							100.00%
Period over which potential acquisition-related contingent consideration would be payable								5 years
Potential acquisition-related contingent consideration, low end of range	0							0
Potential acquisition-related contingent consideration, high end of range	14,400,000							14,400,000
Term over which the subordinated notes are payable								3 years
Consideration transferred
Cash paid								35,000,000
Subordinated notes issued								7,700,000
Contingent consideration	$ 8,300,000							$ 8,300,000

Intangible Assets (Details) (USD $)	12 Months Ended
Intangible Assets (Details) (USD $)	May 31, 2013	May 31, 2012	May 31, 2011
Intangible assets
Gross Amount	$ 98,238,000	$ 72,373,000
Accumulated Amortization	(45,810,000)	(37,904,000)
Net Carrying	52,428,000	34,469,000
Amortization expense	7,700,000	5,600,000	5,000,000
Expected Amortization Expense
2014	8,660,000
2015	8,375,000
2016	7,037,000
2017	5,335,000
2018	4,207,000
Thereafter	18,814,000
Total	52,428,000
Customer relationships
Intangible assets
Gross Amount	69,901,000	45,050,000
Accumulated Amortization	(27,422,000)	(21,642,000)
Net Carrying	42,479,000	23,408,000
Customer relationships \| Minimum
Intangible assets
Useful Life	5 years
Customer relationships \| Maximum
Intangible assets
Useful Life	7 years
Software/Technology
Intangible assets
Useful Life	3 years
Gross Amount	14,336,000	13,177,000
Accumulated Amortization	(7,629,000)	(6,691,000)
Net Carrying	6,707,000	6,486,000
Amortization expense	600,000	300,000	400,000
Software/Technology \| Minimum
Intangible assets
Useful Life	3 years
Software/Technology \| Maximum
Intangible assets
Useful Life	15 years
Covenants not to compete
Intangible assets
Gross Amount	8,069,000	7,969,000
Accumulated Amortization	(7,523,000)	(7,167,000)
Net Carrying	546,000	802,000
Covenants not to compete \| Minimum
Intangible assets
Useful Life	2 years
Covenants not to compete \| Maximum
Intangible assets
Useful Life	5 years
Other
Intangible assets
Gross Amount	5,932,000	6,177,000
Accumulated Amortization	(3,236,000)	(2,404,000)
Net Carrying	$ 2,696,000	$ 3,773,000
Other \| Minimum
Intangible assets
Useful Life	2 years
Other \| Maximum
Intangible assets
Useful Life	5 years

Accrued Expenses and Other Current Liabilities (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2013	May 31, 2012
Accrued Expenses and Other Current Liabilities
Accrued salaries, wages and related employee benefits	$ 23,662	$ 17,195
Contingent consideration	5,144	2,371
Accrued worker compensation and health benefits	3,667	3,678
Deferred revenues	2,623	5,390
Other accrued expenses	12,743	10,700
Total accrued expenses and other liabilities	$ 47,839	$ 39,334

Long-Term Debt (Details) (USD $)	12 Months Ended
Long-Term Debt (Details) (USD $)	May 31, 2013 item	May 31, 2012
Long-Term Debt
Long-term debt	$ 60,267,000	$ 40,229,000
Less: Current maturities	(7,418,000)	(5,971,000)
Long-term debt, net of current maturities	52,849,000	34,258,000
Expenses related to deferred financing costs		(671,000)
Principal payments due under all borrowing agreements
2014	7,418,000
2015	7,986,000
2016	4,012,000
2017	40,399,000
2018	130,000
Thereafter	322,000
Total	60,267,000	40,229,000
Senior credit facility
Long-Term Debt
Long-term debt	39,567,000	25,000,000
Current borrowing capacity	125,000,000
Maximum borrowing capacity	150,000,000
Maximum borrowing capacity in non-U.S. dollar currencies	30,000,000
Maximum amount available for the issuance of letters of credit	10,000,000
Outstanding borrowings	39,600,000
Outstanding letters of credit	3,300,000
Number of consecutive fiscal quarters used for calculating Funded Debt Leverage Ratio	4
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
Cost capitalized		600,000
Expenses related to deferred financing costs		100,000
Gain on early extinguishment of debt		800,000
Principal payments due under all borrowing agreements
Total	39,567,000	25,000,000
Senior credit facility \| Minimum
Long-Term Debt
Funded Debt Leverage Ratio at which the entity will bear the maximum interest rate margin	2.5
Funded Debt Leverage Ratio for additional interest payment	3.0
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	3.0
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)	2.00%
Senior credit facility \| Base rate
Long-Term Debt
Reference rate, description	base rate
Senior credit facility \| Base rate \| Minimum
Long-Term Debt
Margin (as a percent)	(0.25%)
Senior credit facility \| Base rate \| Maximum
Long-Term Debt
Margin (as a percent)	(1.25%)
Notes payable
Long-Term Debt
Long-term debt	15,740,000	12,532,000
Interest rate, minimum (as a percent)	0.00%
Interest rate, maximum (as a percent)	4.00%
Unamortized discount		100,000
Principal payments due under all borrowing agreements
Total	15,740,000	12,532,000
Notes payable \| Minimum
Long-Term Debt
Maturity term from the date of acquisition	3 years
Market interest rate (as a percent)	2.00%
Notes payable \| Maximum
Long-Term Debt
Maturity term from the date of acquisition	5 years
Market interest rate (as a percent)	4.00%
Other
Long-Term Debt
Long-term debt	4,960,000	2,697,000
Principal payments due under all borrowing agreements
Total	$ 4,960,000	$ 2,697,000

Obligations under Capital Leases (Details) (USD $)			12 Months Ended
Obligations under Capital Leases (Details) (USD $)	May 31, 2013	May 31, 2012	May 31, 2013 Minimum	May 31, 2013 Maximum
Obligations under capital leases
Required monthly payments			$ 1,000	$ 72,000
Effective interest rate (as a percent)			3.00%	9.00%
Net book value of assets under capital lease	16,100,000	5,900,000
Future minimum lease payments
2014	7,795,000
2015	5,598,000
2016	3,699,000
2017	1,571,000
2018	238,000
Thereafter	168,000
Total Minimum Lease Payments	19,069,000
Less: amount representing interest	(1,380,000)
Present value of minimum lease payments	17,689,000
Less: current portion of obligations under capital leases	(6,766,000)	(5,951,000)
Obligations under capital leases, net of current portion	$ 10,923,000	$ 13,094,000

Commitments and Contingencies (Details) (USD $)	12 Months Ended
Commitments and Contingencies (Details) (USD $)	May 31, 2013	May 31, 2012	May 31, 2011
Future minimum lease payments
2014	$ 3,708,000
2015	2,254,000
2016	1,628,000
2017	1,097,000
2018	738,000
Thereafter	1,202,000
Total	10,627,000
Total rent expense	7,200,000	5,400,000	4,200,000
Lawsuits for alleged quality defects
Litigation
Number of lawsuits yet to be filed	0
Acquisition-related contingencies
Litigation
Potential acquisition-related contingent consideration, low end of range	0
Potential acquisition-related contingent consideration, high end of range	$ 24,600,000
Period over which potential acquisition-related contingent consideration would be payable	4 years

Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	May 31, 2013	May 31, 2012
Liabilities:
Contingent consideration	$ 5,144	$ 2,371
Recurring basis \| Level 3
Liabilities:
Contingent consideration	15,438	13,513
Total Liabilities	15,438	13,513
Recurring basis \| Total
Liabilities:
Contingent consideration	15,438	13,513
Total Liabilities	$ 15,438	$ 13,513

Employee Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
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	6 months
Company match amount of employee contributions matched up to 6% of annual compensation (as a percent)	50.00%
Vesting period for employer matching contribution	5 years
Contribution under 401(k) savings plan	$ 2.3	$ 2.1	$ 1.9
Maximum
Defined Contribution Plan
Percentage of employee's annual compensation for which the company contributes a matching contribution	6.00%

Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Income before provision for income taxes from:
U.S. operations	$ 29,573	$ 27,951	$ 22,422
Foreign operations	(5,307)	5,686	4,416
Income before provision for income taxes	24,266	33,637	26,838
Current
Federal	9,035	8,792	5,921
States and local	1,673	1,762	1,589
Foreign	3,118	2,042	1,444
Reserve for uncertain tax positions	206	47	(231)
Total current	14,032	12,643	8,723
Deferred
Federal	5	216	2,036
States and local	134	105	(359)
Foreign	246	(359)	85
Total deferred	385	(38)	1,762
Net change in valuation allowance	(1,790)	(314)	17
Net deferred	(1,405)	(352)	1,779
Provision for income taxes	12,627	12,291	10,502
Reconciliation of income tax expense at the statutory rate to the effective income tax expense
Federal tax at statutory rate	8,493	11,773	9,393
State taxes, net of federal benefit	1,174	1,213	799
Foreign tax rate differentials	1,744	(307)	(16)
Contingent consideration	(1,156)	(370)
Permanent differences	498	272	585
Goodwill impairment	3,478
Other	186	24	(276)
Change in valuation allowance	(1,790)	(314)	17
Provision for income taxes	$ 12,627	$ 12,291	$ 10,502
Reconciliation of the federal income tax expense
Federal tax at statutory rate (as a percent)	35.00%	35.00%	35.00%
State taxes, net of federal benefit (as a percent)	4.80%	3.60%	2.90%
Foreign tax rate differentials (as a percent)	7.20%	(0.90%)	(0.10%)
Contingent consideration (as a percent)	(4.80%)	(1.10%)	0.00%
Permanent differences (as a percent)	2.10%	0.80%	2.20%
Goodwill impairment (as a percent)	14.30%	0.00%	0.00%
Other (as a percent)	0.80%	0.00%	(1.00%)
Change in valuation allowance (as a percent)	(7.40%)	(0.90%)	0.10%
Total provision for income taxes (as a percent)	52.00%	36.50%	39.10%

Income Taxes (Details 2) (USD $)	12 Months Ended
Income Taxes (Details 2) (USD $)	May 31, 2013	May 31, 2012	May 31, 2011
Deferred income tax assets
Allowance for doubtful accounts	$ 745,000	$ 941,000
Inventory	637,000	490,000
Intangible assets	5,220,000	5,144,000
Accrued expenses	2,505,000	2,670,000
Net operating loss carryforward	3,314,000	3,757,000
Capital lease obligation	452,000	587,000
Share-based compensation	4,690,000	3,314,000
Other	37,000	65,000
Deferred income tax assets	17,600,000	16,968,000
Valuation allowance	(2,701,000)	(4,491,000)
Net deferred income tax assets	14,899,000	12,477,000
Deferred income tax liabilities
Property and equipment	(7,142,000)	(7,675,000)
Goodwill	(7,390,000)	(4,907,000)
Intangible assets	(9,277,000)	(2,607,000)
Other	(83,000)	(304,000)
Deferred income tax liabilities	(23,892,000)	(15,493,000)
Net deferred income taxes	(8,993,000)	(3,016,000)
Changes in company's gross unrecognized tax benefits, excluding interest and penalties
Balance at the beginning of the period	971,000	375,000	502,000
Additions for tax positions related to the current fiscal year	31,000	24,000	31,000
Additions for tax positions related to prior years	93,000	44,000	54,000
Decrease for tax positions related to prior years		(22,000)	(119,000)
Current year acquisitions		561,000
Impact of foreign exchange fluctuation	(24,000)
Settlements	(4,000)
Reduction related to the expiration of statutes of limitations	(6,000)	(11,000)	(93,000)
Balance at the end of the period	1,061,000	971,000	375,000
Unrecognized tax benefits including penalties and interest, that would affect the effective tax rate, if recognized	1,400,000	1,200,000	400,000
Anticipated decrease in unrecognized tax benefits, excluding interest and penalties within the next 12 months	600,000
Net (loss) income of foreign subsidiaries	(6,900,000)	4,300,000
Deferred tax liability recognized for the remittance of undistributed international earnings	0
State
Income taxes
Net operating losses	1,500,000
Foreign Country
Income taxes
Net operating losses	$ 10,000,000

Capitalization (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	May 31, 2011	May 31, 2013 item	May 31, 2011	May 31, 2012
Capitalization
Number of shares of common stock offered in public offering	3,754,061
Common stock price per share (in dollars per share)	$ 16.00		$ 16.00
Number of shares of common stock sold	989,660
Number of shares of common stock sold by a selling stockholder	2,764,401
Net proceeds from the offering	$ 14,700		$ 14,682
Number of votes per share		1
Preferred stock, shares authorized		10,000,000		10,000,000
Preferred stock, shares outstanding		0

Capitalization (Details 2) (USD $)	12 Months Ended
Capitalization (Details 2) (USD $)	May 31, 2013	May 31, 2012	May 31, 2011	May 31, 2010
Equity awards
Number of plans prior to entity's IPO	2
Number of additional awards available for grant	0
Stock option awards
Equity awards
Stock options outstanding (in shares)	2,464,000	2,549,000	2,867,000	2,925,000
Recognized share-based compensation expense	$ 3,100,000	$ 3,200,000	$ 3,300,000
Unrecognized compensation cost, net of estimated forfeitures, related to stock option awards	700,000
Weighted-average period over which unrecognized compensation cost is expected to be recognized	3 months 18 days
Additional disclosures
Cash proceeds from options exercised	829,000	2,484,000	95,000
Aggregate intrinsic value of options exercised	1,012,000	4,439,000	97,000
Restricted stock unit awards
Equity awards
Unvested restricted stock units outstanding (in shares)	555,000
Recognized share-based compensation expense	$ 2,900,000	$ 1,900,000	$ 500,000
Weighted-average period over which unrecognized compensation cost is expected to be recognized	2 years 6 months
2009 Plan
Equity awards
Vesting period	4 years
Number of shares authorized for grants	2,286,000
Number of shares available for future grants	1,449,000
2009 Plan \| Incentive stock options
Equity awards
Expiration term	10 years
2009 Plan \| Non-qualified stock options
Equity awards
Expiration term	10 years

Capitalization (Details 3) (USD $)	12 Months Ended
Capitalization (Details 3) (USD $)	May 31, 2013	May 31, 2012	May 31, 2011
Common Stock Options
Granted (in shares)	0
Stock option awards
Common Stock Options
Outstanding at beginning of year (in shares)	2,549,000	2,867,000	2,925,000
Granted (in shares)		5,000	35,000
Exercised (in shares)	(85,000)	(307,000)	(11,000)
Expired or forfeited (in shares)		(16,000)	(82,000)
Outstanding at end of year (in shares)	2,464,000	2,549,000	2,867,000
Weighted Average Exercise Price (in dollar per share)
Outstanding at beginning of year (in dollars per share)	$ 12.82	$ 12.27	$ 12.29
Granted (in dollars per share)		$ 22.35	$ 10.03
Exercised (in dollars per share)	$ 9.66	$ 8.07	$ 8.35
Expired or forfeited (in dollars per share)		$ 7.69	$ 12.77
Outstanding at end of year (in dollars per share)	$ 12.93	$ 12.82	$ 12.27
Options exercisable and weighted average grant date fair value
Options exercisable at end of year (in shares)	1,907,000	1,339,000	952,000
Weighted average grant date fair value (per share) of options granted during the period		$ 8.46	$ 4.47

Capitalization (Details 4) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	May 31, 2013
Options Outstanding
Total Options Outstanding (in shares)	2,464
Options Exercisable
Number Exercisable (in shares)	1,907
Aggregate Intrinsic Value
Options Outstanding (in dollars)	$ 20,813
Options Exercisable (in dollars)	$ 16,384
$6.15-$13.08
Outstanding and exercisable options
Exercise price, lower range limit (in dollars per share)	$ 6.15
Exercise price, upper range limit (in dollars per share)	$ 13.08
Options Outstanding
Total Options Outstanding (in shares)	360
Weighted Average Remaining Life	5 years 6 months
Weighted Average Exercise Price (in dollars per share)	$ 9.70
Options Exercisable
Number Exercisable (in shares)	343
Weighted Average Exercise Price (in dollars per share)	$ 9.69
$13.09-$22.35
Outstanding and exercisable options
Exercise price, lower range limit (in dollars per share)	$ 13.09
Exercise price, upper range limit (in dollars per share)	$ 22.35
Options Outstanding
Total Options Outstanding (in shares)	2,104
Weighted Average Remaining Life	6 years 3 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 13.49
Options Exercisable
Number Exercisable (in shares)	1,564
Weighted Average Exercise Price (in dollars per share)	$ 13.47

Capitalization (Details 5) (USD $)	12 Months Ended		1 Months Ended		12 Months Ended
Capitalization (Details 5) (USD $)	May 31, 2013	May 31, 2012	Jun. 30, 2012 Non-employee directors item	Oct. 31, 2011 Non-employee directors item	May 31, 2013 Non-employee directors	May 31, 2012 Non-employee directors	May 31, 2013 Restricted stock unit awards	May 31, 2012 Restricted stock unit awards	May 31, 2011 Restricted stock unit awards
Capitalization
Recognized share-based compensation expense							$ 2,900,000	$ 1,900,000	$ 500,000
Unrecognized compensation cost, net of estimated forfeitures, related to restricted stock unit awards							7,800,000
Weighted-average period over which unrecognized compensation cost is expected to be recognized							2 years 6 months
Number of fully vested common stock granted					13,000	9,000
Number of non-employee directors to whom fully vested common stock is granted			5	5
Shares vested							123,000	52,000
Fair value of shares vested			300,000	200,000			1,900,000	500,000
Shares withheld by company for employees' tax obligations							37,000	16,000
Payments for employees' tax obligations	$ 809,000	$ 283,000

Segment Disclosure (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2013 item	May 31, 2012	May 31, 2011
Segment Disclosure
Number of operating segments									3
Financial information by segment
Revenues	$ 144,505	$ 133,661	$ 137,729	$ 113,387	$ 127,090	$ 104,118	$ 114,220	$ 91,447	$ 529,282	$ 436,875	$ 338,589
Gross profit	38,543	34,206	41,905	33,717	37,471	29,584	35,215	27,420	148,371	129,690	103,403
Income (loss) from operations	(881)	4,982	15,747	7,706	11,009	5,422	13,696	5,971	27,554	36,098	29,611
Depreciation and amortization									26,647	22,024	18,592
Intangible assets, net	52,428				34,469				52,428	34,469
Total assets	376,660				329,816				376,660	329,816
Operating segments \| Services
Financial information by segment
Revenues									380,851	349,793	283,139
Gross profit									98,907	94,413	77,883
Income (loss) from operations									40,325	39,932	31,856
Depreciation and amortization									18,296	17,763	15,979
Intangible assets, net	14,527				17,180				14,527	17,180
Total assets	200,326				204,209				200,326	204,209
Operating segments \| International
Financial information by segment
Revenues									126,840	59,466	36,798
Gross profit									32,319	19,106	12,922
Income (loss) from operations									(8,246)	3,262	3,539
Depreciation and amortization									6,200	2,342	1,396
Intangible assets, net	27,520				6,390				27,520	6,390
Total assets	138,108				82,579				138,108	82,579
Operating segments \| Products and Systems
Financial information by segment
Revenues									33,301	40,083	26,105
Gross profit									16,947	18,578	13,239
Income (loss) from operations									7,286	8,271	5,123
Depreciation and amortization									2,229	1,831	1,083
Intangible assets, net	9,600				10,095				9,600	10,095
Total assets	37,948				43,914				37,948	43,914
Corporate and eliminations
Financial information by segment
Revenues									(11,710)	(12,467)	(7,453)
Gross profit									198	(2,407)	(641)
Income (loss) from operations									(11,811)	(15,367)	(10,907)
Depreciation and amortization									(78)	88	134
Intangible assets, net	781				804				781	804
Total assets	278				(886)				278	(886)
Corporate and eliminations \| Services
Financial information by segment
Revenues									4,900	2,800	1,400
Corporate and eliminations \| International
Financial information by segment
Revenues									600	900	300
Corporate and eliminations \| Products and Systems
Financial information by segment
Revenues									$ 6,000	$ 9,100	$ 4,400

Segment Disclosure (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2013	May 31, 2012	May 31, 2011
Revenue and long-lived assets by geographic area
Revenues	$ 144,505	$ 133,661	$ 137,729	$ 113,387	$ 127,090	$ 104,118	$ 114,220	$ 91,447	$ 529,282	$ 436,875	$ 338,589
Long-lived assets	236,117				194,815				236,117	194,815
United States
Revenue and long-lived assets by geographic area
Revenues									347,423	336,081	277,585
Long-lived assets	122,727				130,813				122,727	130,813
Other Americas
Revenue and long-lived assets by geographic area
Revenues									55,379	40,337	25,338
Long-lived assets	28,148				37,109				28,148	37,109
Europe
Revenue and long-lived assets by geographic area
Revenues									106,416	42,820	25,192
Long-lived assets	85,171				26,766				85,171	26,766
Asia-Pacific
Revenue and long-lived assets by geographic area
Revenues									20,064	17,637	10,474
Long-lived assets	$ 71				$ 127				$ 71	$ 127

Selected Quarterly Financial Information (unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2013	May 31, 2012	May 31, 2011
Selected Quarterly Financial Information (unaudited)
Revenues	$ 144,505	$ 133,661	$ 137,729	$ 113,387	$ 127,090	$ 104,118	$ 114,220	$ 91,447	$ 529,282	$ 436,875	$ 338,589
Cost of revenues	101,254	94,736	91,529	75,526	85,252	70,574	75,263	60,527
Depreciation	4,708	4,719	4,295	4,144	4,367	3,960	3,742	3,500
Gross profit	38,543	34,206	41,905	33,717	37,471	29,584	35,215	27,420	148,371	129,690	103,403
Selling, general and administrative expenses	27,729	27,209	23,362	23,492	23,533	20,806	19,378	19,381	101,792	83,098	65,983
Research and engineering	646	754	530	517	290	578	602	589	2,447	2,059	2,150
Depreciation and amortization	2,246	2,473	2,167	1,895	1,668	1,805	1,503	1,479	8,781	6,455	5,386
Acquisition-related expense, net	(1,135)	(1,212)	99	107	971	973	36		(2,141)	1,980
Goodwill impairment	9,938								9,938
Income from operations	(881)	4,982	15,747	7,706	11,009	5,422	13,696	5,971	27,554	36,098	29,611
Net income attributable to Mistras Group, Inc.	$ (4,549)	$ 2,751	$ 9,163	$ 4,281	$ 7,132	$ 3,037	$ 7,956	$ 3,228	$ 11,646	$ 21,353	$ 16,431
Earnings per common share:
Basic (in dollars per share)	$ (0.16)	$ 0.10	$ 0.33	$ 0.15	$ 0.25	$ 0.11	$ 0.29	$ 0.12	$ 0.41	$ 0.77	$ 0.61
Diluted (in dollars per share)	$ (0.16)	$ 0.11	$ 0.32	$ 0.15	$ 0.25	$ 0.11	$ 0.28	$ 0.11	$ 0.40	$ 0.74	$ 0.61

Related Party Transactions (Details) (Shareholder and officer, USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013
Related Party Transactions
Total rent payments	$ 0.8
France
Related Party Transactions
Total rent payments	$ 0.2