AAR (AIR) 10-K 11 Jul 18 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	Jun. 29, 2018	Nov. 30, 2017
Document and Entity Information
Entity Registrant Name	AAR CORP
Entity Central Index Key	1,750
Document Type	10-K
Document Period End Date	May 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--05-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,344
Entity Common Stock, Shares Outstanding		34,740,330
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Sales:
Sales from products	$ 1,040.7	$ 944.8	$ 930.1
Sales from services	707.6	646	595.3
Total sales	1,748.3	1,590.8	1,525.4
Costs and operating expenses:
Cost of products	840.5	787.5	785.3
Cost of services	613.2	539.9	507
Selling, general and administrative	208.6	181.1	157.6
Total costs and operating expenses	1,662.3	1,508.5	1,449.9
Operating income	86	82.3	75.5
Other expenses	(0.9)		(0.4)
Interest expense	(8)	(5.3)	(6.4)
Interest income	0.1	0.1	0.2
Income from continuing operations before provision for income taxes	77.2	77.1	68.9
Provision for income taxes	3.5	25.1	23.4
Income from continuing operations	73.7	52	45.5
Income (Loss) from discontinued operations, net of tax	(58.1)	4.5	2.2
Net income	$ 15.6	$ 56.5	$ 47.7
Earnings per share - basic:
Earnings from continuing operations	$ 2.14	$ 1.53	$ 1.30
Earnings (Loss) from discontinued operations	(1.70)	0.13	0.07
Earnings per share - basic	0.44	1.66	1.37
Earnings per share - diluted:
Earnings from continuing operations	2.11	1.51	1.30
Earnings (Loss) from discontinued operations	(1.70)	0.13	0.07
Earnings per share - diluted	$ 0.41	$ 1.64	$ 1.37

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income	$ 15.6	$ 56.5	$ 47.7
Other comprehensive income, net of tax:
Currency translation adjustments, net of tax	2	(0.6)
Unrecognized pension and post retirement costs, net of tax expense (benefit) of $2.4 in 2018, $2.8 in 2017, and ($2.1) in 2016	5.9	5.1	(4)
Total other comprehensive income (loss), net of tax	7.9	4.5	(4)
Comprehensive income	$ 23.5	$ 61	$ 43.7

CONSOLIDATED STATEMENTS OF COM4

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Unrecognized pension and post retirement costs, tax expense (benefit)	$ 2.4	$ 2.8	$ (2.1)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	May 31, 2018	May 31, 2017
Current assets:
Cash and cash equivalents	$ 31.1	$ 10.3
Restricted cash	10.5
Accounts receivable, net	202	234.5
Inventories	460.7	433.4
Rotable assets and equipment on or available for short-term lease	87.2	70.7
Assets of discontinued operations - current	125	120.4
Other current assets	26.2	19.1
Total current assets	942.7	888.4
Property, plant and equipment, at cost:
Land	4.5	4.3
Buildings and improvements	107.4	97.5
Equipment and furniture and fixtures	235.7	222.9
Property, plant and equipment, gross	347.6	324.7
Accumulated depreciation	(214.4)	(207.5)
Property, plant and equipment, net of accumulated depreciation	133.2	117.2
Other assets:
Goodwill	118.7	105.6
Intangible assets, net	27.8	30.6
Rotable assets supporting long-term programs	183.4	159.6
Assets of discontinued operations - non-current		97.8
Other non-current assets	118.9	104.9
Total other assets	448.8	498.5
Total assets	1,524.7	1,504.1
Current liabilities:
Current maturities of long-term debt		0.1
Accounts and trade notes payable	170	164.2
Accrued liabilities	138.3	139.9
Liabilities of discontinued operations	25	30.8
Total current liabilities	333.3	335
Long-term debt, less current maturities	177.2	154.1
Deferred tax liabilities	15.7	37.2
Other liabilities and deferred income	62.2	63.6
Total noncurrent liabilities	255.1	254.9
Equity:
Preferred stock, $1.00 par value, authorized 250,000 shares; none issued
Common stock, $1.00 par value, authorized 100,000,000 shares; issued 45,300,786 and 45,175,302 shares at cost, respectively	45.3	45.2
Capital surplus	470.5	460.8
Retained earnings	733.2	727.9
Treasury stock, 10,585,165 and 10,820,844 shares at cost, respectively	(280.7)	(279.8)
Accumulated other comprehensive loss	(32)	(39.9)
Total equity	936.3	914.2
Total liabilities and equity	$ 1,524.7	$ 1,504.1

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	May 31, 2018	May 31, 2017
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, authorized shares	250,000	250,000
Preferred stock, issued shares	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, authorized shares	100,000,000	100,000,000
Common stock, issued shares	45,300,786	45,175,302
Treasury stock, shares	10,585,165	10,820,844

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Millions	Total Equity	Common Stock	Capital Surplus	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Balance at May. 31, 2015	$ 845.1	$ 44.9	$ 442.6	$ 644.3	$ (246.3)	$ (40.4)
CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY
Net income	47.7			47.7			$ 47.7
Cash dividends	(10.4)			(10.4)
Stock option activity	6.7		4.4		2.3
Restricted stock activity	(0.3)		4.5		(4.8)
Repurchase of shares	(18.8)				(18.8)
Other	(0.2)		(0.2)
Other comprehensive income (loss), net of tax	(4)					(4)	(4)
Balance at May. 31, 2016	865.8	44.9	451.3	681.6	(267.6)	(44.4)
CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY
Net income	56.5			56.5			56.5
Cash dividends	(10.2)			(10.2)
Stock option activity	12		3.1		8.9
Restricted stock activity	5.4	0.3	6.4		(1.3)
Repurchase of shares	(19.8)				(19.8)
Other comprehensive income (loss), net of tax	4.5					4.5	4.5
Balance at May. 31, 2017	914.2	45.2	460.8	727.9	(279.8)	(39.9)	914.2
CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY
Net income	15.6			15.6			15.6
Cash dividends	(10.3)			(10.3)
Stock option activity	12.1		0.9		11.2
Restricted stock activity	9.9	0.1	8.8		(1)
Repurchase of shares	(13.1)				(13.1)
Other comprehensive income (loss), net of tax	7.9					7.9	7.9
Balance at May. 31, 2018	$ 936.3	$ 45.3	$ 470.5	$ 733.2	$ (280.7)	$ (32)	$ 936.3

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Cash flows provided from operating activities:
Net income	$ 15.6	$ 56.5	$ 47.7
Less: Income (Loss) from discontinued operations	(58.1)	4.5	2.2
Income from continuing operations	73.7	52	45.5
Adjustments to reconcile income to net cash provided from (used in) operating activities:
Depreciation and intangible amortization	40.5	35.7	33.2
Amortization of stock-based compensation	15.3	11	6.5
Deferred tax provision (benefit)	(12.9)	12.5	5.5
Gain on sale of product line		(2.6)
Changes in certain assets and liabilities, net of acquisitions:
Accounts receivable	35.9	(14.7)	(2.2)
Inventories	(25.8)	(23.3)	(19.5)
Rotable spares and equipment on or available for short-term lease	(16.6)	(3.1)	2.8
Rotable assets supporting long-term programs	(38.5)	(82.5)	(10.2)
Accounts and trade notes payable	1.8	19.6	13.8
Accrued and other liabilities	8	6.5	(31.1)
Other	(25.6)	(24.6)	1.7
Net cash provided from (used in) operating activities-continuing operations	55.8	(13.5)	46
Net cash provided from (used in) operating activities-discontinued operations	8.5	35.3	(13.9)
Net cash provided from operating activities	64.3	21.8	32.1
Cash flows used in investing activities:
Property, plant and equipment expenditures	(22)	(25.2)	(40.1)
Proceeds from asset disposals	8.6	6.5	0.1
Payments for acquisitions	(22.9)	(12.5)	(4.8)
Other	(2.3)	(2.7)	1
Net cash used in investing activities-continuing operations	(38.6)	(33.9)	(43.8)
Net cash provided from (used in) investing activities-discontinued operations	(4.3)	3.8	26.9
Net cash used in investing activities	(42.9)	(30.1)	(16.9)
Cash flows provided by (used in) financing activities:
Short-term borrowings (repayments), net	(1)	21	60
Proceeds (Repayments) on long-term borrowings	24.8
Proceeds (Repayments) on long-term borrowings		(10)	(70.6)
Cash dividends	(10.3)	(10.2)	(10.4)
Purchase of treasury stock	(13.1)	(19.8)	(18.8)
Stock option exercises	11.6	8.5	1.8
Other	(0.3)	0.1	(0.4)
Net cash provided from (used in) financing activities-continuing operations	11.7	(10.4)	(38.4)
Net cash used in financing activities-discontinued operations	(1.7)	(1.7)
Net cash provided from (used in) financing activities	10	(12.1)	(38.4)
Effect of exchange rate changes on cash	(0.1)	(0.5)	(0.3)
Increase (Decrease) in cash and cash equivalents	31.3	(20.9)	(23.5)
Cash, cash equivalents, and restricted cash at beginning of year	10.3	31.2	54.7
Cash, cash equivalents, and restricted cash at end of year	$ 41.6	$ 10.3	$ 31.2

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	May 31, 2018
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies Description of Business AAR CORP. is a diversified provider of services and products to the worldwide commercial aviation and government and defense markets. Services and products include: aviation supply chain and parts support programs; maintenance, repair and overhaul of airframes, landing gear, and certain other airframe components; design and manufacture of specialized pallets, shelters, and containers; airlift services; aircraft modifications and aircraft and engine sales and leasing. We serve commercial, defense and governmental aircraft fleet operators, original equipment manufacturers, and independent service providers around the world, and various other domestic and foreign military customers. Principles of Consolidation The accompanying Consolidated Financial Statements include the accounts of the Company and its majority-owned subsidiaries after elimination of intercompany accounts and transactions. The equity method of accounting is used for investments in other companies in which we have significant influence; generally this represents common stock ownership of at least 20% and not more than 50%. Revenue Recognition Sales and related cost of sales for product sales are generally recognized upon shipment of the product to the customer. Our standard terms and conditions provide that title passes to the customer when the product is shipped to the customer. Sales of certain defense products are recognized upon customer acceptance, which includes transfer of title. Sales from services and the related cost of services are generally recognized when customer-owned material is shipped back to the customer. We have adopted this accounting policy because at the time the customer-owned material is shipped back to the customer, all services related to that material are complete as our service agreements generally do not require us to provide services at customer sites. Furthermore, serviced units are typically shipped to the customer immediately upon completion of the related services. Sales and related cost of sales for certain large airframe maintenance contracts and performance-based logistics programs are recognized by the percentage of completion method, based on the relationship of costs incurred to date to the estimated total costs. Net favorable cumulative catch-up adjustments recognized during fiscal 2018, 2017, and 2016 were $3.6 million, $8.5 million, and $3.7 million, respectively, resulting from changes to the estimated profitability of these contracts. Lease revenues are recognized as earned. Income from monthly or quarterly rental payments is recorded in the pertinent period according to the lease agreement. However, for leases that provide variable rents, we recognize lease income on a straight-line basis. In addition to a monthly lease rate, some engine leases require an additional rental amount based on the number of hours the engine is used in a particular month. Lease income associated with these contingent rentals is recorded in the period in which actual usage is reported to us by the lessee, which is normally the month following the actual usage. Certain supply chain management programs we provide to our customers contain multiple elements or deliverables, such as program and warehouse management, parts distribution, and maintenance and repair services. We recognize revenue for each element or deliverable that can be identified as a separate unit of accounting at the time of delivery based upon the relative fair value of the products and services. In June 2016, the U.S. Air Force awarded the new contract for the KC-10 Extender Contractor Logistics Support Program ("KC-10 Program") to a competitor. Our principal services under the prior contract for the KC-10 Program were completed in January 2017; however, we have provided limited services since that date. Sales for the KC-10 Program during fiscal 2018, 2017 and 2016 were $29.1 million, $110.6 million, and $148.1 million, respectively. Gross profit for the KC-10 Program during fiscal 2018, 2017 and 2016 was $4.8 million, $8.7 million, and $16.0 million, respectively. Allowance for Doubtful Accounts We maintain an allowance for doubtful accounts to reflect the expected uncollectibility of accounts receivable based on past collection history and specific risks identified among uncollected accounts. In determining the required allowance, we consider factors such as general and industry-specific economic conditions, customer credit history, and our customers' current and expected future financial performance. The majority of our customers are recurring customers with an established payment history. Certain customers are required to undergo an extensive credit check prior to delivery of products or services. Goodwill and Other Intangible Assets In accordance with Accounting Standards Codification ("ASC") 350, Intangibles—Goodwill and Other , goodwill and other intangible assets deemed to have indefinite lives are not amortized, but are subject to annual impairment tests. We review and evaluate our goodwill and indefinite life intangible assets for potential impairment at a minimum annually, on May 31, or more frequently if circumstances indicate that impairment is possible. Our annual goodwill impairment test over the last three years has used a combination of the qualitative approach and the two-step quantitative approach to evaluate goodwill for impairment. As of May 31, 2018, we have five reporting units with only four of the reporting units assigned goodwill. Our four reporting units with goodwill include two in our Aviation Services segment (Aviation Supply Chain and Maintenance, Repair, and Overhaul) and two in our Expeditionary Services segment (Airlift and Mobility). We utilized the qualitative assessment approach for all reporting units. We performed the annual qualitative analysis as of May 31, 2018 for the four reporting units with assigned goodwill and concluded it was more likely than not that the fair value of each reporting unit exceeded its carrying value, and thus no impairment charge was recorded. Changes in the carrying amount of goodwill by segment for fiscal 2018 and 2017 are as follows: Aviation Expeditionary Total Balance as of May 31, 2016 $ $ $ Foreign currency translation adjustments ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2017 Acquisition — Foreign currency translation adjustments — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2018 $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Intangible assets with finite useful lives are amortized on a straight-line basis over their estimated useful lives. Intangible assets, other than goodwill, are comprised of the following: May 31, 2018 Gross Accumulated Net Amortizable intangible assets: Customer relationships $ $ ) $ Developed technology ) Lease agreements ) FAA certificate ) Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ) Unamortized intangible assets: Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ May 31, 2017 Gross Accumulated Net Amortizable intangible assets: Customer relationships $ $ ) $ Developed technology ) Lease agreements ) FAA certificate ) Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ) Unamortized intangible assets: Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Customer relationships are being amortized over 10-20 years, developed technology is being amortized over 7-15 years, lease agreements are being amortized over 5-18 years, and the FAA certificate is being amortized over 20 years. Amortization expense recorded during fiscal 2018, 2017 and 2016 was $4.7 million, $4.2 million, and $4.4 million, respectively. The estimated aggregate amount of amortization expense for intangible assets in each of the next five fiscal years is $4.1 million in 2019, $3.7 million in 2020, $3.7 million in 2021, $2.9 million in 2022 and $2.3 million in 2023. Foreign Currency Our foreign subsidiaries utilize the local currency as their functional currency. All balance sheet accounts of foreign subsidiaries transacting business in currencies other than the U.S. dollar are translated at year-end exchange rates. Revenues and expenses are translated at average exchange rates during the year. Translation adjustments are excluded from the results of operations and are recorded in stockholders' equity as a component of accumulated other comprehensive loss until such subsidiaries are liquidated. Cash Cash and cash equivalents consist of highly liquid instruments which have original maturities of three months or less when purchased. Restricted cash represents cash on hand required to be set aside by a contractual agreement related to receivable securitization arrangements. Generally, the restrictions related to the receivable securitization arrangements lapse at the time we remit the customer payments collected by us as servicer of previously sold customer receivables to the purchaser. Financial Instruments and Concentrations of Market or Credit Risk Financial instruments that potentially subject us to concentrations of market or credit risk consist principally of trade receivables. While our trade receivables are diverse and represent a number of entities and geographic regions, the majority are with the U.S. government and its contractors and entities in the aviation industry. Accounts receivable due from the U.S. government were $33.0 million and $29.4 million at May 31, 2018 and 2017, respectively. We perform regular evaluations of customer payment experience, current financial condition, and risk analysis. We may require collateral in the form of security interests in assets, letters of credit, and/or obligation guarantees from financial institutions for transactions executed on other than normal trade terms. The carrying amounts of cash and cash equivalents, accounts receivable, and accounts and trade notes payable approximate fair value because of the short-term maturity of these instruments. The carrying value of long-term debt bearing a variable interest rate approximates fair value. Fair value estimates are made at a specific point in time based on relevant market information about the financial instrument. These estimates are subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. Changes in assumptions could significantly affect the estimates. Inventories Inventories are valued at the lower of cost or market (estimated net realizable value). Cost is determined by the specific identification, average cost, or first-in, first-out methods. From time-to-time, we purchase aircraft and engines for disassembly to individual parts and components. Costs are assigned to these individual parts and components utilizing list prices from original equipment manufacturers and recent sales history. The following is a summary of inventories: May 31, 2018 2017 Aircraft and engine parts, components and finished goods $ $ Raw materials and parts Work-in-process ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Rotable Assets and Equipment under Leases Lease revenue is recognized as earned. The cost of the asset under lease is the original purchase price plus overhaul costs. Depreciation is computed using the straight-line method over the estimated service life of the equipment. The balance sheet classification of equipment under lease is generally based on lease term, with fixed-term leases less than twelve months generally classified as short-term and all others generally classified as long-term. Equipment on short-term lease includes aircraft engines and parts on or available for lease to satisfy customers' immediate short-term requirements. The leases are renewable with fixed terms, which generally vary from one to twelve months. Future rent due to us under non-cancelable leases during each of the next five fiscal years is $26.2 million in 2019, $25.7 million in 2020, $25.0 million in 2021, $24.5 million in 2022, and $24.5 million in 2023. Rotable Assets Supporting Long-Term Programs Rotable assets supporting long-term programs consists of rotable component parts used to support long-term supply chain programs. The assets are being depreciated on a straight-line basis over their estimated useful lives. Property, Plant and Equipment We record property, plant and equipment at cost. Depreciation is computed on the straight-line method over useful lives of 10-40 years for buildings and improvements and 3-10 years for equipment, furniture and fixtures, and capitalized software. Leasehold improvements are amortized over the shorter of the estimated useful life or the term of the applicable lease. Repair and maintenance expenditures are expensed as incurred. Upon sale or disposal, cost and accumulated depreciation are removed from the accounts, and related gains and losses are included in results of operations. In accordance with ASC 360, Property, Plant and Equipment , we are required to test for impairment of long-lived assets whenever events or changes in circumstances indicate the carrying value of an asset may not be recoverable from its undiscounted cash flows. We utilize certain assumptions to estimate future undiscounted cash flows, including demand for our services, future market conditions and trends, business development pipeline of opportunities, current and future lease rates, lease terms, and residual values. Income Taxes We are subject to income taxes in the U.S., state, and several foreign jurisdictions. In the ordinary course of business, there can be transactions and calculations where the ultimate tax determination is uncertain. We recognize deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns in accordance with applicable accounting guidance for accounting for income taxes, using currently enacted tax rates in effect for the year in which the differences are expected to reverse. We record a valuation allowance when necessary to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets are reduced by a valuation allowance if, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. Both positive and negative evidence are considered in forming our judgment as to whether a valuation allowance is appropriate, and more weight is given to evidence that can be objectively verified. Valuation allowances are reassessed whenever there are changes in circumstances that may cause a change in judgment. The accounting for uncertainty in income taxes requires a more-likely-than-not threshold for financial statement recognition of tax positions taken or expected to be taken in a tax return. Where necessary, we record a liability for the difference between the benefit recognized for financial statement purposes and the tax position taken or expected to be taken on our tax return. To the extent that our assessment of such tax positions changes, the change in estimate is recorded in the period in which the determination is made. Supplemental Information on Cash Flows Supplemental information on cash flows is as follows: For the Year Ended 2018 2017 2016 Interest paid $ $ $ Income taxes paid Income tax refunds and interest received During fiscal 2018, treasury stock increased $0.9 million reflecting the repurchase of common shares of $13.1 million, restricted stock activity of $1.0 million and the re-issuance of shares upon exercise of stock options, net of shares withheld to satisfy statutory tax obligations, of $11.2 million. During fiscal 2017, treasury stock increased $12.2 million reflecting the repurchase of common shares of $19.8 million, restricted stock grants of $1.3 million and the re-issuance of shares upon exercise of stock options, net of shares withheld to satisfy statutory tax obligations, of $8.9 million. During fiscal 2016, treasury stock increased $21.3 million reflecting the repurchase of common shares of $18.8 million, restricted stock grants of $4.8 million and the re-issuance of shares upon exercise of stock options, net of shares withheld to satisfy statutory tax obligations, of $2.3 million. Use of Estimates We have made estimates and utilized certain assumptions relating to the reporting of assets and liabilities and the disclosures of contingent liabilities to prepare these Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States. Actual results could differ from those estimates. New Accounting Pronouncements Revenue from Contracts with Customers In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers , which provides guidance for revenue recognition. This ASU affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets. This ASU will supersede the revenue recognition requirements in ASC 605, Revenue Recognition , and most industry-specific guidance. This ASU will also supersede certain cost guidance included in Subtopic 605-35, Revenue Recognition-Construction-Type and Production-Type Contracts . In August 2015, the FASB issued ASU No. 2015-14 which deferred the effective date of the new standard by one year so that it will be effective for us beginning June 1, 2018. We will adopt this ASU using the modified retrospective transition method in the first quarter of fiscal 2019. Under this method, we will be required to recognize the cumulative effect of adopting this ASU as of June 1, 2018. We have substantially completed our assessment of the new ASU and are finalizing the quantification of our adoption adjustments as well as preparing the new required disclosures for the first quarter of fiscal 2019. We have identified three areas where the new ASU will impact our revenue recognition. First, we have certain contracts under which we manufacture products with no alternative use and the Company has an enforceable right to payment from the customer. As a result, the Company will be required to record revenue for these contracts over time as opposed to at the time of shipment which is our current policy today. Second, we have contracts under which we perform repair services on customer-owned assets which will also transition to an over time approach compared to our current policy of recognizing revenue at the time of shipment. Third, we have certain contracts in which revenue is recognized using the percentage of completion method over the expected term of the contract. The new ASU will result in the reduction of the contract term used for revenue recognition as certain contracts include unexercised customer option years or include customer rights to terminate the contract without significant penalty. We expect the cumulative effect for the adoption of the new ASU will result in a decrease to retained earnings of approximately $20 million as of June 1, 2018. We will establish new Contract asset and Contract liability balance sheet accounts and will reclassify certain amounts from Accounts receivable, Inventories, Other non-current assets, and Other liabilities and deferred income into these new accounts. Other New Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases . This ASU amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets, including those classified as operating leases under the current accounting guidance. In addition, this ASU will require new qualitative and quantitative disclosures about the Company's leasing activities. This new standard will be effective for us beginning June 1, 2019, with early adoption permitted. This ASU requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. We are in the preliminary phases of assessing the effect of this ASU on our portfolio of leases. While this assessment continues, we have not yet selected a transition date nor have we determined the effect of this ASU on our consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which amends ASC Topic 718, Compensation—Stock Compensation . This ASU requires excess tax benefits or deficiencies for share-based payments to be recorded in the period shares vest as income tax expense or benefit, rather than within equity. Cash flows related to excess tax benefits are now included in operating activities and are no longer classified as a financing activity. We adopted this ASU on June 1, 2017 and recognized excess tax benefits of $2.9 million as an income tax benefit in fiscal 2018. We have also presented the excess tax benefits within operating activities in the consolidated statement of cash flows for fiscal 2018. As permitted, we adopted the statement of cash flow presentation guidance on a prospective basis with no adjustments to the previously reported amounts. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash . This ASU requires restricted cash to be included within beginning and ending total cash amounts reported in the consolidated statements of cash flows as well as increased disclosure requirements. As permitted, we have early adopted this ASU in fiscal 2018. The ASU is required to be adopted on a retroactive basis; however, we did not have restricted cash in our prior periods reported. In February 2018, the FASB issued ASU 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . This ASU permits the reclassification of tax effects stranded in accumulated other comprehensive income to retained earnings as a result of the Tax Cuts and Jobs Act (the "Tax Reform Act"). This new standard will be effective for us beginning June 1, 2019 with early adoption permitted. We are currently evaluating the impact of this new standard on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . This ASU requires an employer to report the service cost component of net periodic pension benefit cost in the same line item as other compensation costs for those related employees. Other components of net pension cost, including interest, expected return on plan assets, and actuarial gains and losses are to be presented outside of operating income. This new standard requires retrospective treatment for the classification of pension costs and will be effective for us beginning June 1, 2018. With the majority of our pension plans frozen and total service cost, including administrative expenses, of $2.4 million and $2.5 million in fiscal 2018 and 2017, respectively, this ASU is not expected to have a material impact on our consolidated financial statements.

Discontinued Operations

Discontinued Operations	12 Months Ended
	May 31, 2018
Discontinued Operations
Discontinued Operations	2. Discontinued Operations During the third quarter of fiscal 2018, we decided to pursue the sale of our Contractor-Owned, Contractor-Operated ("COCO") business previously included in our Expeditionary Services segment. Due to this strategic shift, the assets, liabilities, and results of operations of our COCO business have been reported as discontinued operations for all periods presented. Goodwill was allocated to this business based on its relative fair value to the reporting unit. The fair value of the reporting unit was determined based on a combination of the expected net proceeds upon sale and a discounted cash flow analysis. As the fair value of the COCO business was below its carrying value, a goodwill impairment charge of $9.8 million, representing the estimated loss on disposal, was recorded in the third quarter of fiscal 2018. Our COCO business completed certain contracts in the second quarter of fiscal 2018. As the aircraft supporting these contracts were not placed on new contracts combined with the continued decline in operational tempo within the U.S. Department of Defense ("DoD") and an excess supply of aircraft assets in the market, we determined there was an impairment triggering event and tested the recoverability of our COCO assets. As a result, we recognized impairment and other charges of $54.2 million in the second quarter of fiscal 2018. The fair value of the aircraft and related assets was based on available market data for similar assets. In the first quarter of fiscal 2016, we recognized a gain of $27.7 million net of expenses representing the receipt of the contingent consideration related to the sale of our Telair Cargo Group. Discontinued operations also includes the results of our former metal machining operation which was shutdown in the first quarter of fiscal 2017. No amounts for general corporate overhead or interest expense were allocated to discontinued operations during the periods presented. Unless otherwise noted, amounts and disclosures throughout these Notes to Consolidated Financial Statements relate to our continuing operations. Operating results for discontinued operations were comprised of the following: For the Year Ended May 31, 2018 2017 2016 Sales $ $ $ Cost of sales ) ) ) Asset impairments ) — — Selling, general and administrative expenses ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating loss from discontinued operations ) ) ) Gain on sale of Telair Cargo Group — — Provision for income taxes (benefit) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (Loss) from discontinued operations $ ) $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ During the third quarter of fiscal 2016, we recognized $2.8 million of income tax expense in discontinued operations related to changes in estimates associated with tax provision to federal income tax return filing differences. During the fourth quarter of fiscal 2017, we recognized an income tax benefit in discontinued operations of $6.7 million for an effective settlement of a previously reserved tax position. The carrying amounts of the major classes of assets and liabilities for our discontinued operations are as follows: May 31, 2018 2017 Inventory, rotable assets, and equipment $ $ Accounts receivable, net Goodwill — Other assets ​ ​ ​ ​ ​ ​ ​ ​ Assets of discontinued operations $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities—current $ $ Liabilities—non-current — ​ ​ ​ ​ ​ ​ ​ ​ Liabilities of discontinued operations $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Sale of Receivables

Sale of Receivables	12 Months Ended
	May 31, 2018
Sale of Receivables
Sale of Receivables	3. Sale of Receivables On February 23, 2018, we entered into a Purchase Agreement with Citibank N.A. ("Purchaser") for the sale, from time to time, of certain accounts receivable due from certain customers (the "Purchase Agreement"). Under the Purchase Agreement, the maximum amount of receivables sold is limited to $150 million. The term of the Purchase Agreement runs through February 22, 2019, however, the Purchase Agreement may also be terminated earlier under certain circumstances. The term of the Purchase Agreement shall be automatically extended for annual terms unless either party provides advance notice that they do not intend to extend the term. We have no retained interests in the sold receivables, other than limited recourse obligations in certain circumstances, and only perform collection and administrative functions for the Purchaser. We account for these receivable transfers as sales under ASC 860, Transfers and Servicing , and de-recognize the sold receivables from our Consolidated Balance Sheet. During fiscal 2018, we sold $239.6 million of receivables under the Purchase Agreement and remitted $167.9 million to the Purchaser on their behalf. As of May 31, 2018, we have collected cash of $10.5 million which has not yet been remitted to the Purchaser and has been classified as Restricted cash on our Consolidated Balance Sheet. During fiscal 2018, we incurred purchase discount and other fees of $0.9 million which are recognized as Other expenses on our Consolidated Statements of Income.

Financing Arrangements

Financing Arrangements	12 Months Ended
	May 31, 2018
Financing Arrangements
Financing Arrangements	4. Financing Arrangements Debt Outstanding A summary of the carrying amount of our debt is as follows: May 31, 2018 2017 Revolving Credit Facility expiring November 1, 2021 with interest payable monthly $ $ Term loan due November 1, 2021 with interest payable monthly — Industrial revenue bond (secured by property, plant and equipment) due August 1, 2018 with interest payable monthly Capital lease obligations — ​ ​ ​ ​ ​ ​ ​ ​ Total debt Current maturities of debt — ) Debt issuance costs, net ) ) ​ ​ ​ ​ ​ ​ ​ ​ Long-term debt $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At May 31, 2018, our variable rate and fixed rate debt had a fair value that approximates its carrying value and are classified as Level 2 in the fair value hierarchy. On October 18, 2017, we entered into a Credit Agreement with the Canadian Imperial Bank of Commerce, as lender (the "Credit Agreement"). The Credit Agreement provided a Canadian $31 million term loan with the proceeds used to fund the acquisition of two maintenance, repair, and overhaul ("MRO") facilities in Canada from Premier Aviation. The term loan is due in full at the expiration of the Credit Agreement on November 1, 2021 unless terminated earlier pursuant to the terms of the Credit Agreement. Interest is payable monthly on the term loan at the offered fluctuating Canadian Dollar Offer Rate plus 125 to 225 basis points based on certain financial measurements if a Bankers' Acceptances loan, or at the offered fluctuating Prime Rate plus 25 to 125 basis points based on certain financial measurements, if a Prime Rate loan. We maintain a Revolving Credit Facility with various financial institutions, as lenders and Bank of America, N.A., as administrative agent for the lenders which provides the Company an aggregate revolving credit commitment amount of $500 million. The Company, under certain circumstances, has the ability to request an increase to the revolving credit commitment by an aggregate amount of up to $250 million, not to exceed $750 million in total. On November 1, 2016, we entered into an amendment to our Revolving Credit Facility which extended the maturity of the Revolving Credit Facility to November 1, 2021, eliminated the condition of no material adverse change for credit extensions and modified certain other provisions. Borrowings under the Revolving Credit Facility bear interest at the offered Eurodollar Rate plus 100 to 200 basis points based on certain financial measurements if a Eurodollar Rate loan, or at the offered fluctuating Base Rate plus 0 to 100 basis points based on certain financial measurements if a Base Rate loan. The industrial revenue bond that matures on August 1, 2018 has been classified as a long-term liability due to our intent and ability to refinance this bond on a long-term basis using our Revolving Credit Facility. Our financing arrangements also require us to comply with leverage and interest coverage ratios, maintain a minimum net working capital level, and comply with certain affirmative and negative covenants, including those relating to financial reporting and notification, payment of indebtedness, cash dividends, taxes and other obligations, compliance with applicable laws, and limitations on additional liens, indebtedness, acquisitions, investments and disposition of assets. The Revolving Credit Facility also requires our significant domestic subsidiaries, and any subsidiaries that guarantee our other indebtedness, to provide a guarantee of payment under the Revolving Credit Facility. At May 31, 2018, we were in compliance with the financial and other covenants in our financing agreements. Borrowing activity under the Revolving Credit Facility during fiscal 2018, 2017 and 2016 is as follows: For the Year Ended May 31, 2018 2017 2016 Maximum amount borrowed $ $ $ Average daily borrowings Average interest rate during the year % % % We also have $9.9 million available under foreign lines of credit.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	May 31, 2018
Stock-Based Compensation
Stock-Based Compensation	5. Stock-Based Compensation We have granted stock-based awards under the AAR CORP. 2013 Stock Plan (the "2013 Stock Plan") and the AAR CORP. Stock Benefit Plan ("Stock Benefit Plan") each of which has been approved by our stockholders. No further awards will be made under the Stock Benefit Plan. Under the 2013 Stock Plan, we are authorized to issue stock options to employees and non-employee directors that allow the grant recipients to purchase shares of common stock at a price not less than the fair market value of the common stock on the date of grant. Generally, stock options awarded expire ten years from the date of grant and are exercisable in three, four or five equal annual increments commencing one year after the date of grant. In addition to stock options, the 2013 Stock Plan also provides for the grant of time-based restricted stock awards and performance-based restricted stock awards. The number of performance-based awards earned, subject to vesting, is based on achievement of certain Company-wide or segment financial goals or stock price targets. The 2013 Stock Plan also provides for the grant of stock appreciation units and restricted stock units; however, to date, no such awards have been granted. Restricted stock grants (whether time-based or performance-based) are designed, among other things, to align employee interests with the interests of stockholders and to encourage the recipient to build a career with us. Restricted stock typically vests over periods of one to five years from date of grant. Restricted stock grants may be performance-based with vesting to occur over periods of three to five years. All restricted stock that has been granted and, if performance-based, earned according to performance criteria carries full dividend and voting rights, regardless of whether it has vested. Substantially all stock options and restricted stock are subject to forfeiture prior to vesting if the employee's employment terminates for any reason other than death, disability or retirement. Since inception, a total of 11,149,000 shares have been granted under the Stock Benefit Plan. We have granted a total of 2,669,000 shares under the 2013 Stock Plan. All future stock awards will be made under the 2013 Stock Plan. There were 2,128,238 shares available for grant under the 2013 Stock Plan as of May 31, 2018. Stock Options During fiscal 2018, 2017, and 2016, we granted stock options with respect to 463,140 shares, 687,000 shares and 488,767 shares, respectively. The weighted average fair value per share of stock options granted during fiscal 2018, 2017 and 2016 was $9.29, $6.50 and $7.48, respectively. The fair value of each stock option grant was estimated on the date of grant using the Black-Scholes option pricing model using the following weighted average assumptions: Stock Options Granted 2018 2017 2016 Risk-free interest rate % % % Expected volatility of common stock % % % Dividend yield % % % Expected option term in years The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. The expected volatility is based on historical volatility of our common stock, and the expected option term represents the period of time that the stock options granted are expected to be outstanding based on historical exercise trends. The dividend yield represents our anticipated cash dividends at the grant date over the expected option term. A summary of stock option activity for the three years ended May 31, 2018 consisted of the following (shares in thousands): 2018 2017 2016 Shares Weighted Shares Weighted Shares Weighted Outstanding at beginning of year $ $ $ Granted $ $ $ Exercised ) $ ) $ ) $ Cancelled ) $ ) $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options exercisable at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The total fair value of stock options that vested during fiscal 2018, 2017, and 2016 was $4.9 million, $3.5 million, and $2.7 million, respectively. The total intrinsic value of stock options exercised during fiscal 2018, 2017, and 2016 was $14.2 million, $4.7 million, and $1.0 million, respectively. The aggregate intrinsic value of options outstanding was $37.4 million and $27.8 million as of May 31, 2018 and 2017, respectively. The tax benefit realized from stock options exercised during fiscal 2018, 2017, and 2016 was $2.9 million, $1.2 million, and $0.2 million, respectively. Expense recognized in selling, general and administrative expenses for stock options during fiscal 2018, 2017, and 2016 was $5.1 million, $4.6 million, and $3.5 million, respectively. As of May 31, 2018, we had $4.6 million of unrecognized compensation expense related to stock options that will be amortized over an average period of 0.7 years. The following table provides additional information regarding stock options outstanding as of May 31, 2018 (shares in thousands): Options Outstanding Options Exercisable Option Number Weighted-Average Weighted- Number Weighted- $12.00 - $20.00 $ $ $20.01 - $26.00 $ $ $26.01 - $38.70 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Restricted Stock We provide executives and other key employees an opportunity to be awarded performance-based and time-based restricted stock. The performance-based awards are contingent upon the achievement of certain performance objectives, including cumulative net income and average return on capital over a three-year performance period. During fiscal 2018, 2017, and 2016, we granted 108,440, 212,583, and 119,929 of performance-based restricted shares, respectively. Time-based restricted shares of 24,425, 39,100, and 42,557 were granted to executives and key employees during fiscal 2018, 2017, and 2016, respectively. We also award time-based restricted stock to our non-employee directors as part of their annual compensation. Time-based restricted shares of 55,000, 50,625, and 47,083 were granted to members of the Board of Directors during fiscal 2018, 2017, and 2016, respectively. The fair value of restricted shares is the market value of our common stock on the date of grant. Expense recognized in selling, general and administrative expenses for all restricted share programs during fiscal 2018, 2017, and 2016 was $10.2 million, $6.4 million, and $3.2 million, respectively. Restricted share activity during the fiscal year ended May 31, 2018 was as follows (shares in thousands): Number of Weighted Average Nonvested at May 31, 2017 $ Granted $ Vested ) $ Forfeited ) $ ​ ​ ​ ​ ​ ​ ​ ​ Nonvested at May 31, 2018 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of May 31, 2018 we had $4.1 million of unearned compensation related to restricted shares that will be amortized to expense over a weighted average period of 2.5 years.

Income Taxes

Income Taxes	12 Months Ended
	May 31, 2018
Income Taxes
Income Taxes	6. Income Taxes On December 22, 2017, the Tax Reform Act was enacted which significantly revised the U.S. corporate income tax system. The Tax Reform Act, among other things, reduced the current corporate federal income tax rate to 21% from 35%, changed bonus depreciation regulations and limited deductions for executive compensation. The income tax rate reduction in the Tax Reform Act is effective January 1, 2018 which results in a blended federal statutory tax rate of 29.2% in fiscal 2018. We re-measured our deferred tax assets and liabilities based on the tax rate at which they are expected to reverse in the future, which is either at a federal rate of 29.2% for reversals in fiscal 2018 or 21% for reversals in fiscal 2019 and subsequent years. During the third quarter of fiscal 2018, we recognized an income tax benefit of $13.0 million for the re-measurement impact on a provisional basis as permitted under Staff Accounting Bulletin No. 118, which allows the use of a measurement period, similar to that used in business combinations, to account for the impacts of the Tax Reform Act. In the fourth quarter of fiscal 2018, we completed our assessment and recognized an additional income tax benefit of $1.1 million resulting in a total income tax benefit of $14.1 million in fiscal 2018 for the re-measurement impact. The provision for income tax on income from continuing operations includes the following components: For the Year Ended 2018 2017 2016 Current: Federal $ $ $ State Foreign ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The provision for income taxes on pre-tax income differs from the amount computed by applying the U.S. federal statutory income tax rate of 29.2% for fiscal 2018 and 35.0% for fiscal 2017 and 2016 to income from continuing operations before provision for income taxes due to the following: For the Year Ended 2018 2017 2016 Provision for income tax (benefit) at the federal statutory rate $ $ $ Deferred tax re-measurement from the Tax Reform Act ) — — Excess tax benefits from stock-based compensation ) — — State net operating losses Change in valuation allowance for state deferred tax assets ) ) ) Prior period adjustments — — ) Effective settlement of prior tax position — ) — Other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision for income tax $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ During the third quarter of fiscal 2016, we completed a reconciliation of our tax basis assets and liabilities and an analysis of our income tax payable which identified prior year immaterial errors netting to $0.2 million with $1.5 million recognized as income tax expense in discontinued operations and $1.3 million recognized as income tax benefit within income from continuing operations. Income before provision for income taxes includes the following components: For the Year Ended 2018 2017 2016 Domestic $ $ $ Foreign ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities and assets result primarily from the differences in the timing of the recognition of transactions for financial reporting and income tax purposes. Our deferred tax liabilities and assets consist of the following components: May 31, 2018 2017 Deferred tax assets: Inventory costs $ $ Impairments Postretirement benefits Employee benefits State net operating losses Other ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax assets Valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax assets net of valuation allowance ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: Tangible and intangible assets ) ) Other ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax liabilities $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of May 31, 2018, we have determined that the realization of our deferred tax assets is more likely than not and that a valuation allowance is not required except for certain state deferred tax assets, including net operating losses. The change in the valuation allowance was primarily the result of the expected utilization of a portion of these state net operating losses. Our net operating losses have carry forward periods that range from 5 to 20 years. Our history of operating earnings, our expectations for continued future earnings, the nature of certain of our deferred tax assets and the scheduled reversal of deferred tax liabilities, primarily related to depreciation, support the recoverability of the majority of the deferred tax assets. Income tax receivable at May 31, 2018 was $1.0 million and was included in Other current assets on the Consolidated Balance Sheet. Income tax payable at May 31, 2017 was $12.3 million and was included in Accrued Liabilities on the Consolidated Balance Sheet. A reconciliation of the beginning and ending amounts of unrecognized tax benefits was as follows: For the Year Ended 2018 2017 2016 Balance, beginning of year $ $ $ Additions for tax positions of prior years — Effective settlement of prior tax position — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In fiscal 2017, the reserve for unrecognized tax benefits decreased primarily as a result of effective settlement of tax positions for prior tax years which occurred upon the settlement of an IRS examination. Income tax expense in fiscal 2017 included a benefit of $2.2 million and discontinued operations included a benefit of $6.7 million for these effective settlements. All of our unrecognized tax benefits as of May 31, 2018 and 2017 would be recorded as a component of income tax expense or income from discontinued operations, if recognized. We accrue interest and penalties related to unrecognized tax benefits as a component of income tax expense. Fiscal years 2015 and subsequent are open for examination. Various states and foreign jurisdictions also remain open subject to their applicable statute of limitations.

Earnings Per Share

Earnings Per Share	12 Months Ended
	May 31, 2018
Earnings Per Share
Earnings Per Share	7. Earnings Per Share The computation of basic earnings per share is based on the weighted average number of common shares outstanding during each period. The computation of diluted earnings per share is based on the weighted average number of common shares outstanding during the period plus, when their effect is dilutive, incremental shares consisting of shares subject to stock options, shares issuable upon vesting of restricted stock awards and shares to be issued upon conversion of convertible debt. In accordance with ASC 260-10-45, Share-Based Payment Arrangements and Participating Securities and the Two-Class Method , our unvested restricted stock awards are deemed participating securities since these shares are entitled to participate in dividends declared on common shares. During periods of net income, the calculation of earnings per share for common stock excludes income attributable to unvested restricted stock awards from the numerator and excludes the dilutive impact of those shares from the denominator. During periods of net loss, no effect is given to the participating securities because they do not share in the losses of the Company. The following tables provide a reconciliation of the computations of basic and diluted earnings per share information for each of the years in the three-year period ended May 31, 2018 (shares in millions). For the Year Ended 2018 2017 2016 Basic and Diluted EPS: Income from continuing operations $ $ $ Less income attributable to participating shares ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income from continuing operations attributable to common shareholders Income (Loss) from discontinued operations attributable to common shareholders ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to common shareholders for earnings per share $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average common shares outstanding—basic Additional shares from assumed exercise of stock options ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average common shares outstanding—diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share—basic: Earnings from continuing operations $ $ $ Earnings (Loss) from discontinued operations ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share—basic $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share—diluted: Earnings from continuing operations $ $ $ Earnings (Loss) from discontinued operations ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share—diluted $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At May 31, 2018, the average market price of our common shares was in excess of the exercise prices of all of our outstanding options. At May 31, 2017 and 2016, respectively, outstanding options to purchase 11,200 shares and 1,374,200 shares of common stock were not included in the computation of diluted earnings per share, because the exercise price of these options was greater than the average market price of the common shares for the period then ended.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	May 31, 2018
Employee Benefit Plans
Employee Benefit Plans	8. Employee Benefit Plans Defined Benefit Plans Prior to January 1, 2000, the pension plan for domestic salaried and non-union hourly employees had a benefit formula based primarily on years of service and compensation. Effective January 1, 2000, we converted our defined benefit plan for substantially all domestic salaried and certain hourly employees to a cash balance pension plan. Under the cash balance pension plan, the retirement benefit is expressed as a dollar amount in an account that grows with annual pay-based credits and interest on the account balance. The interest crediting rate under our cash balance plan is determined quarterly and is equal to 100% of the average 30-year treasury rate for the second month preceding the applicable quarter published by the Internal Revenue Service. The average interest crediting rate under our cash balance plan for the fiscal year ended May 31, 2018 was 4.46%. Effective June 1, 2005, the existing cash balance plan was frozen and the annual pay-based credits were discontinued. Also effective June 1, 2005, the defined contribution plan was modified to include increased employer contributions and an enhanced profit sharing formula. Defined pension benefits for certain union hourly employees are based primarily on a fixed amount per year of service and the plan was frozen in fiscal 2018. We also have a defined benefit pension plan covering certain employees in the Netherlands. Benefit formulas are based generally on years of service and compensation. We also have a benefit plan which provides benefits to certain retired outside directors. In fiscal 2001, we froze the plan for any new members of the Board of Directors and no current directors participate in this plan. The change to our projected benefit obligation and the fair value of our plan assets for our pension plans was as follows: May 31, 2018 2017 Change in projected benefit obligation: Projected benefit obligation at beginning of year $ $ Service cost Interest cost Participant contributions Net actuarial gain ) ) Benefits and administrative payments ) ) Plan change — Foreign currency translation adjustment ​ ​ ​ ​ ​ ​ ​ ​ Projected benefit obligation at end of year $ $ ​ ​ ​ ​ ​ ​ ​ ​ Change in the fair value of plan assets: Fair value of plan assets at beginning of year $ $ Actual return on plan assets Employer contributions Participant contributions Benefits and administrative payments ) ) Foreign currency translation adjustment ​ ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at end of year $ $ ​ ​ ​ ​ ​ ​ ​ ​ Funded status at end of year $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in the Consolidated Balance Sheets consisted of the following: May 31, 2018 2017 Non-current assets $ $ — Accrued liabilities ) ) Other liabilities and deferred income ) ) ​ ​ ​ ​ ​ ​ ​ ​ Funded status at end of year $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts recognized in accumulated other comprehensive loss at May 31, 2018 and 2017, respectively, consisted of the following: May 31, 2018 2017 Actuarial loss $ $ Prior service credit ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For our frozen defined benefit plan for domestic salaried and non-union hourly employees, plan assets exceeded both the projected benefit obligation and the accumulated benefit obligation by $0.5 million. For all of our other pension plans, both the projected benefit obligation and the accumulated benefit obligation are in excess of the individual plans' assets. The accumulated benefit obligation for all pension plans was $140.2 million and $140.0 million at May 31, 2018 and 2017, respectively. Net Periodic Benefit Cost Pension expense charged to the Consolidated Statements of Income includes the following components: For the Year Ended 2018 2017 2016 Service cost $ $ $ Interest cost Expected return on plan assets ) ) ) Curtailment — — Amortization of prior service cost — — Recognized net actuarial loss ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The estimated amounts to be amortized from accumulated other comprehensive loss into expense during fiscal 2019 are as follows: Net actuarial loss $ Prior service cost — ​ ​ ​ ​ ​ Total $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assumptions The assumptions used in accounting for our plans are estimates of factors including, among other things, the amount and timing of future benefit payments. The following table presents the key weighted-average assumptions used in the measurement of our projected benefit obligations: May 31, 2018 2017 Discount rate: Domestic plans % % International plan Rate of compensation increase: Domestic plans n/a % International plans % A summary of the weighted-average assumptions used to determine net periodic pension expense is as follows: For the Year Ended 2018 2017 2016 Discount rate: Domestic plans % % % International plan Rate of compensation increase: Domestic plans % % % International plan Expected long-term rate on plan assets: Domestic plans % % % International plan The discount rate was determined by projecting the expected future benefit payments as defined for the projected benefit obligation, discounting those expected payments using a theoretical zero-coupon spot yield curve derived from a universe of high-quality bonds as of the measurement date, and solving for the single equivalent discount rate that resulted in the same projected benefit obligation. Plan Assets The following table sets forth the actual asset allocation and target allocations for our U.S. pension plans: May 31, Target Asset 2018 2017 Equity securities % % 45 - 75 % Fixed income securities 15 - 45 % Other 0 - 25 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ % % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The assets of U.S pension plans are invested in compliance with the Employee Retirement Income Security Act of 1974. The investment goals are to provide a total return that, over the long term, optimizes the long-term return on plan assets at an acceptable risk, and to maintain a broad diversification across asset classes and among investment managers. We believe that there are no significant concentrations of risk within our plan assets as of May 31, 2018. The use of derivatives for the purpose of speculation are not permitted. The assets of the U.S. pension plans are invested primarily in equity and fixed income mutual funds, individual common stocks, and fund-of-funds hedge funds. The assets of the non-domestic plan are invested in funds-of-funds where each fund holds a portfolio of equity and fixed income mutual funds. To develop our expected long-term rate of return assumption on domestic plans, we use long-term historical return information for our targeted asset mix and current market conditions. The expected return for each asset class is weighted based on the target asset allocation to develop the expected long-term rate of return on plan assets assumption. While consideration is given to recent performance, the assumption represents a long-term, prospective rate of return. The following table sets forth by level, within the fair value hierarchy, pension plan assets at their fair value as of May 31, 2018: Level 1 1 Level 2 2 Level 3 3 Total Equity securities: U.S. mutual funds $ $ — $ — $ International mutual funds — — Fixed income: Government securities and corporate bond mutual funds — — Funds-of-funds — Hedge funds — — Insurance annuities — — Cash and cash equivalents — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following table sets forth by level, within the fair value hierarchy, pension plan assets at their fair value as of May 31, 2017: Level 1 1 Level 2 2 Level 3 3 Total Equity securities: U.S. mutual funds $ $ — $ — $ International mutual funds — — Fixed income: Government securities and corporate bond mutual funds — — Funds-of-funds — Hedge funds — — Cash and cash equivalents — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1 Quoted prices in active markets for identical assets that we have the ability to access as of the reporting date. 2 Inputs other than quoted prices included within Level 1 that are directly observable for the asset or indirectly observable through corroboration with observable market data. 3 Unobservable inputs, such as internally developed pricing models or third party valuations for the asset due to little or no market activity for the asset. The following table presents the reconciliation of Level 3 pension assets measured at fair value for the fiscal years ended May 31, 2018 and 2017: Hedge Funds Fund-of-funds Insurance Annuities Total Balance as of May 31, 2016 $ $ $ — $ Sales — ) — ) Return on plan assets related to assets still held at May 31, 2017 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2017 — Purchases — — Sales ) — — ) Return on plan assets related to assets still held at May 31, 2018 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2018 $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation Techniques Used to Determine Fair Value Cash equivalents are investments with maturities of three months or less when purchased. The fair values are based on observable market prices and categorized as Level 1. With respect to individually held equity securities, including investments in U.S. and international securities, the trustees obtain prices from pricing services, whose prices are obtained from direct feeds from market exchanges, which we are able to independently corroborate. Equity securities held individually are primarily traded on exchanges that contain only actively traded securities, due to the volume trading requirements imposed by these exchanges. Equity securities are valued based on quoted prices in active markets and categorized as Level 1. Equity and fixed income mutual funds are maintained by investment companies that hold certain investments in accordance with a stated set of fund objectives, which are consistent with our overall investment strategy. The values of some of these funds are publicly quoted. For equity and fixed income mutual funds which are publicly quoted, the funds are valued based on quoted prices in active markets and have been categorized as Level 1. As certain of our funds-of-funds investments are also derived from quoted prices in active markets, we have categorized certain funds-of-funds investments as Level 2. Hedge fund investments include those seeking to maximize absolute returns using a broad range of strategies to enhance returns and provide additional diversification. The fair value of hedge funds is determined using net asset value or its equivalent subject to certain restrictions, such as a lock-up period. As we may be limited in our ability to redeem the investments at the measurement date or within a reasonable period of time, the hedge fund investments are categorized as Level 3. Our other Level 3 investments require the utilization of unobservable inputs resulting in Level 3 treatment in the fair value hierarchy. Future Benefit Payments and Funding The following table summarizes our estimated future pension payments by fiscal year: Fiscal Year 2019 2020 2021 2022 2023 2024 to Estimated future pension payments $ $ $ $ $ $ Our contribution policy for the domestic plans is to contribute annually, at a minimum, an amount which is deductible for federal income tax purposes and that is sufficient to meet actuarially computed pension benefits. For our Netherlands pension plan, our policy is to fund at least the minimum amount required by the local laws and regulations. We anticipate contributing approximately $2.9 million to our pension plans during fiscal 2019. Postretirement Benefits Other Than Pensions We provide health and life insurance benefits for certain eligible retirees. The postretirement plan is unfunded and in fiscal 1995, we completed termination of postretirement health and life insurance benefits attributable to future services of collective bargaining and other domestic employees. The unfunded projected benefit obligation for this plan was $0.4 million and $0.7 million as of May 31, 2018 and 2017, respectively. We have omitted substantially all of the required disclosures related to this plan because the plan is not material to our consolidated financial position or results of operations. Defined Contribution Plan The defined contribution plan is a profit sharing plan that is intended to qualify as a 401(k) plan under the Internal Revenue Code. Under the plan, employees may contribute up to 75% of their pretax compensation, subject to applicable regulatory limits. We may make matching contributions up to 5% of compensation as well as discretionary profit sharing contributions. Our contributions vest on a pro-rata basis during the first three years of employment. We also provide profit sharing benefits for certain executives and key employees to supplement the benefits provided by the defined contribution plan. Expense charged to the Consolidated Statements of Income for our matching contributions, including profit sharing contributions, was $9.2 million in fiscal 2018, $11.6 million in fiscal 2017 and $10.3 million in fiscal 2016 for these plans.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	May 31, 2018
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss	9. Accumulated Other Comprehensive Loss Changes in our accumulated other comprehensive loss ("AOCL") by component for each of the years in the three-year period ended May 31, 2018 were as follows (all amounts are net of tax): Currency Pension Total Balance as of June 1, 2015 $ $ ) $ ) Reclassifications within AOCL ) — Other comprehensive loss before reclassifications — ) ) Amounts reclassified from AOCL — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive loss — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2016 ) ) ) Other comprehensive income (loss) before reclassifications ) Amounts reclassified from AOCL — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive income (loss) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2017 ) ) ) Other comprehensive income before reclassifications Amounts reclassified from AOCL — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive income ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2018 $ $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	May 31, 2018
Commitments and Contingencies
Commitments and Contingencies	10. Commitments and Contingencies On October 3, 2003, we entered into a sale-leaseback transaction whereby we sold and leased back a facility located in Garden City, New York. The lease is classified as an operating lease. Net proceeds from the sale of the facility were $14.0 million and the cost and related accumulated depreciation of the facility of $9.5 million and $4.6 million, respectively, were removed from the Consolidated Balance Sheet at the time of sale. The gain realized on the sale of $9.1 million has been deferred and is being amortized over the 20-year lease term. As of May 31, 2018 and 2017, the unamortized balance of the deferred gain was approximately $2.5 million and $2.9 million, respectively, and is included in Other liabilities and deferred income on the Consolidated Balance Sheet. In addition to the leases described above, we lease other facilities and equipment under agreements that are classified as operating leases that expire at various dates through 2034. Future minimum payments under all operating leases at May 31, 2018 are as follows: 2019 $ 2020 2021 2022 2023 2024 and thereafter Rental expense for facilities and equipment during fiscal years 2018, 2017, and 2016 was $23.5 million, $22.9 million, and $21.3 million, respectively. We enter into purchase obligations which arise in the ordinary course of business and represent a binding commitment to acquire inventory, including raw materials, parts and components, as well as equipment to support the operations of our business. The aggregate amount of purchase obligations due in each of the next five fiscal years is $203.4 million in 2019, $43.8 million in 2020, $6.0 million in 2021, none in 2022 and none in 2023. We routinely issue letters of credit and performance bonds in the ordinary course of our business. These instruments are typically issued in conjunction with insurance contracts or other business requirements. The total of these instruments outstanding at May 31, 2018 was approximately $16.7 million. We are involved in various claims and legal actions, including environmental matters, arising in the ordinary course of business. In the opinion of management, the ultimate disposition of these matters will not have a material adverse effect on our consolidated financial condition or results of operations.

Other Noncurrent Assets

Other Noncurrent Assets	12 Months Ended
	May 31, 2018
Other Noncurrent Assets
Other Noncurrent Assets	11. Other Noncurrent Assets At May 31, 2018 and 2017, other noncurrent assets consisted of the following: May 31, 2018 2017 Costs in excess of billings $ $ Assets under deferred compensation plan Cash surrender value of life insurance License fees Investments in joint ventures Other ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ License Fees In June 2011, we entered into a ten-year agreement with Unison Industries to be the exclusive worldwide aftermarket distributor for Unison's electrical components, sensors, switches and other systems for aircraft and industrial uses. In connection with the agreement, we agreed to pay Unison Industries $20.0 million for the exclusive distribution rights with $7.0 million paid in June 2011 and $1.3 million payable by January 31 of each calendar year beginning in January 2012 through 2021. As of May 31, 2018 and 2017, the unamortized balance of the license is $5.6 million and $7.2 million, respectively, and is being amortized over a ten-year period. The current portion of the deferred payments of $1.3 million is recorded in Accrued liabilities and the long-term portion of $2.2 million is included in Other liabilities and deferred income on the Consolidated Balance Sheet. Investments in Joint Ventures During fiscal 2018, we sold interests in two aircraft joint ventures which were accounted for under the equity method of accounting. We received cash proceeds of $7.3 million and recognized a gain on the sale of $0.4 million. As of May 31, 2018, all of our remaining investments in aircraft joint ventures are accounted for under the cost method. Under the terms of servicing agreements with certain of our aircraft joint ventures, we provide administrative services and technical advisory services, including aircraft evaluations, oversight and logistical support of the maintenance process and records management. We also provide evaluation and inspection services prior to the purchase of an aircraft and remarketing services with respect to the divestiture of aircraft by the joint ventures. During fiscal 2018, 2017, and 2016, we were paid $0.4 million, $1.2 million, and $0.9 million, respectively, for such services. Distributions from joint ventures are classified as operating or investing activities in the Consolidated Statements of Cash Flows based upon an evaluation of the specific facts and circumstances of each distribution.

Acquisitions

Acquisitions	12 Months Ended
	May 31, 2018
Acquisitions
Acquisitions	12. Acquisitions On September 19, 2017, we acquired the outstanding shares of two MRO facilities in Canada owned by Premier Aviation for approximately $24.8 million. The purchase price includes $22.9 million paid at closing and deferred consideration of $1.9 million payable September 2018. This business is included in our Aviation Services segment. The amounts recorded for certain assets are preliminary in nature and are subject to adjustment as additional information is obtained about their acquisition date fair value. The final determination of the fair values will be completed within the one year measurement period. The preliminary fair value of assets acquired and liabilities assumed is as follows: Current assets $ Property and equipment Intangible assets, including goodwill Accounts payable and accrued liabilities ) ​ ​ ​ ​ ​ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ On April 10, 2017, we acquired the trading business of ACLAS Global Limited ("ACLAS"). In conjunction with the acquisition, we entered into a multi-year component support and repair contract covering approximately 100 of ACLAS' aircraft. The purchase price of the acquisition was $12.0 million paid at closing with $3.0 million in deferred consideration payable over the next three years. This business operates as part of our Aviation Services segment. The fair value of assets acquired is as follows: Inventory $ Equipment on or available for long-term lease Intangible assets ​ ​ ​ ​ ​ Assets acquired $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ On December 4, 2015, we acquired certain assets of Vantem Modular LLC, which designs, manufactures, and distributes modular shelters. The purchase price of the acquisition was $4.8 million paid at closing with future royalties of up to $5.0 million. This business operates as part of our Expeditionary Services segment. The fair value of net assets acquired is as follows: Current assets $ Equipment Intangible assets Contingent consideration ) ​ ​ ​ ​ ​ Net assets acquired Goodwill ​ ​ ​ ​ ​ Purchase price $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Business Segment Information

Business Segment Information	12 Months Ended
	May 31, 2018
Business Segment Information
Business Segment Information	13. Business Segment Information Segment Reporting Consistent with how our chief operating decision making officer (Chief Executive Officer) evaluates performance and the way we are organized internally, we report our activities in two segments: Aviation Services comprised of supply chain and MRO activities and Expeditionary Services comprised of airlift and mobility activities. The Aviation Services segment consists of aftermarket support and services businesses that provide spares and maintenance support for aircraft operated by our commercial and government/defense customers. Sales in the Aviation Services segment are derived from the sale and lease of a wide variety of new, overhauled and repaired engine and airframe parts and components and aircraft to the commercial aviation and government and defense markets. We provide customized inventory supply chain management, performance based logistics programs, aircraft component repair management services, and aircraft modifications. The segment also includes repair, maintenance and overhaul of aircraft, landing gear and components. Cost of sales consists principally of the cost of product, direct labor, and overhead. The Expeditionary Services segment consists of businesses that provide products and services supporting the movement of equipment and personnel by the U.S. and foreign governments and other non-governmental organizations. Sales in the Expeditionary Services segment are derived from fleet management and operations of customer-owned aircraft and the design and manufacture of pallets, shelters, and containers used to support the U.S. military's requirements for a mobile and agile force. We also design and manufacture advanced composite materials for commercial, business and military aircraft. Cost of sales consists principally of the cost of material to manufacture products, direct labor and overhead. The accounting policies for the segments are the same as those described in Note 1. Our chief operating decision making officer (Chief Executive Officer) evaluates performance based on the reportable segments and utilizes gross profit as a primary profitability measure. Gross profit is calculated by subtracting cost of sales from sales. The assets and certain expenses related to corporate activities are not allocated to the segments. Our reportable segments are aligned principally around differences in products and services. Selected financial information for each segment is as follows: For the Year Ended May 31, 2018 2017 2016 Net sales: Aviation Services $ $ $ Expeditionary Services ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year Ended May 31, 2018 2017 2016 Gross profit: Aviation Services $ $ $ Expeditionary Services ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ May 31, 2018 2017 Total assets: Aviation Services $ $ Expeditionary Services Corporate and discontinued operations ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year Ended May 31, 2018 2017 2016 Capital expenditures: Aviation Services $ $ $ Expeditionary Services Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total continuing operations Discontinued operations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year Ended May 31, 2018 2017 2016 Depreciation and amortization: 1 Aviation Services $ $ $ Expeditionary Services Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total continuing operations Discontinued operations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1 Includes depreciation and amortization of stock-based compensation. The following table reconciles segment gross profit to income from continuing operations before provision for income taxes. For the Year Ended May 31, 2018 2017 2016 Segment gross profit $ $ $ Selling, general and administrative ) ) ) Other expenses ) — ) Interest expense ) ) ) Interest income ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income from continuing operations before provision for income taxes $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The U.S. Department of Defense, other U.S. government agencies and their contractors are our only customers representing 10% or more of total sales in any of the last three fiscal years. Sales by segment for these customers are as follows: For the Year Ended May 31, 2018 2017 2016 Aviation Services $ $ $ Expeditionary Services ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Percentage of total sales % % % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sales by type of product/service was as follows: For the Year Ended May 31, 2018 2017 2016 Aviation supply chain $ $ $ Maintenance, repair and overhaul services Mobility products Airlift — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Geographic Data May 31, 2018 2017 Long-lived assets: United States $ $ Europe Other ​ ​ ​ ​ ​ ​ ​ ​ Total continuing operations Discontinued operations — ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sales to unaffiliated customers in foreign countries (including sales through foreign sales offices of domestic subsidiaries) were approximately $694.0 million (39.7% of total sales), $595.4 million (37.4% of total sales) and $498.0 million (32.6% of total sales) in fiscal 2018, 2017 and 2016, respectively.

Legal Proceedings

Legal Proceedings	12 Months Ended
	May 31, 2018
Legal Proceedings
Legal Proceedings	14. Legal Proceedings We are not a party to any material pending legal proceeding (including any governmental or environmental proceeding) other than routine litigation incidental to our business except for the following: DynCorp International LLC v. AAR Airlift Group, Inc. On September 5, 2015, DynCorp International LLC ("DynCorp") filed a complaint in the United States District Court for the Middle District of Florida, Orlando Division (the "District Court"), accusing AAR Airlift Group, Inc. ("Airlift"), a wholly-owned subsidiary of AAR CORP., of misappropriation of DynCorp information, including trade secrets, and other related allegations, in connection with the submission of proposals in response to the solicitation issued by the U.S. Department of State ("DoS") Bureau of International Narcotics and Law Enforcement Affairs, Office of Aviation in support of the Worldwide Aviation Support Services program ("WASS"). On October 19, 2015, DynCorp filed an amended complaint with the District Court. On January 14, 2016, the District Court granted Airlift's motion to dismiss DynCorp's amended complaint. On February 2, 2016, DynCorp appealed the District Court's order to the United States Court of Appeals for the Eleventh Circuit (the "Eleventh Circuit"). On November 21, 2016, the Eleventh Circuit reversed in part the District Court's dismissal of the amended complaint and remanded the case to the District Court for further proceedings. On January 31, 2018, Airlift and DynCorp filed a joint notice of settlement, advising the District Court that they had reached an agreement in principle to resolve DynCorp's lawsuit and that they expected to file a stipulation of dismissal with prejudice within 14 days. On February 1, 2018, the District Court entered an order dismissing the DynCorp lawsuit without prejudice, subject to the right of any party within 60 days to move the court for the purpose of entering a stipulated form of a final order or judgment or, on good cause shown, to reopen the case for further proceedings. On June 20, 2018, the parties entered into a confidential settlement agreement to dismiss the lawsuit with prejudice without the payment of any money by either party. On June 26, 2018, the District Court entered an order dismissing the lawsuit with prejudice. Department of Justice Investigation The U.S. Department of Justice ("DoJ"), acting through the U.S. Attorney's Office for the Southern District of Illinois, is conducting an investigation of Airlift under the federal civil False Claims Act ("FCA"). The investigation relates to Airlift's performance of several contracts awarded by the U.S. Transportation Command concerning the operations and maintenance of rotary-wing and fixed-wing aircraft in Afghanistan and Africa, as well as several U.S. Navy contracts. In June 2018, the DoJ informed Airlift that part of the investigation was precipitated by a lawsuit filed under the qui tam provisions of the FCA by a former employee of Airlift. That lawsuit remains under seal. Airlift is cooperating with the DoJ investigation.

Selected Quarterly Data (Unaudi

Selected Quarterly Data (Unaudited)	12 Months Ended
	May 31, 2018
Selected Quarterly Data (Unaudited)
Selected Quarterly Data (Unaudited)	15. Selected Quarterly Data (Unaudited) The unaudited selected quarterly data for fiscal years ended May 31, 2018 and 2017 is as follows: Fiscal 2018 First Second Third Fourth Full Sales $ $ $ $ $ Gross profit Income from continuing operations Loss from discontinued operations 1 ) ) ) ) ) Net income (loss) ) Earnings (Loss) per share—basic: 2 Continuing operations Discontinued operations ) ) ) ) ) Earnings per share—basic ) Earnings (Loss) per share—diluted: 2 Continuing operations Discontinued operations ) ) ) ) ) Earnings per share—diluted ) Fiscal 2017 First Second Third Fourth Full Sales $ $ $ $ $ Gross profit Income from continuing operations Income (Loss) from discontinued operations ) ) Net income Earnings (Loss) per share—basic: 2 Continuing operations Discontinued operations ) ) Earnings per share—basic Earnings (Loss) per share—diluted: 2 Continuing operations Discontinued operations ) ) Earnings per share—diluted 1 Loss from discontinued operations in fiscal 2018 includes pre-tax aircraft and other asset impairment charges of $54.2 million in the second quarter and a goodwill impairment charge of $9.8 million in the third quarter. 2 The earnings-per-share computation for the year is a separate, annual calculation. Accordingly, the sum of the quarterly earnings-per-share amounts does not necessarily equal the earnings per share for the year.

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts	12 Months Ended
	May 31, 2018
Allowance for Doubtful Accounts
Allowance for Doubtful Accounts	16. Allowance for Doubtful Accounts May 31, 2018 2017 2016 Balance, beginning of year $ $ $ Provision charged to operations Recoveries, deductions for accounts written off and other reclassifications ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	May 31, 2018
Summary of Significant Accounting Policies
Principles of Consolidation	Principles of Consolidation The accompanying Consolidated Financial Statements include the accounts of the Company and its majority-owned subsidiaries after elimination of intercompany accounts and transactions. The equity method of accounting is used for investments in other companies in which we have significant influence; generally this represents common stock ownership of at least 20% and not more than 50%.
Revenue Recognition	Revenue Recognition Sales and related cost of sales for product sales are generally recognized upon shipment of the product to the customer. Our standard terms and conditions provide that title passes to the customer when the product is shipped to the customer. Sales of certain defense products are recognized upon customer acceptance, which includes transfer of title. Sales from services and the related cost of services are generally recognized when customer-owned material is shipped back to the customer. We have adopted this accounting policy because at the time the customer-owned material is shipped back to the customer, all services related to that material are complete as our service agreements generally do not require us to provide services at customer sites. Furthermore, serviced units are typically shipped to the customer immediately upon completion of the related services. Sales and related cost of sales for certain large airframe maintenance contracts and performance-based logistics programs are recognized by the percentage of completion method, based on the relationship of costs incurred to date to the estimated total costs. Net favorable cumulative catch-up adjustments recognized during fiscal 2018, 2017, and 2016 were $3.6 million, $8.5 million, and $3.7 million, respectively, resulting from changes to the estimated profitability of these contracts. Lease revenues are recognized as earned. Income from monthly or quarterly rental payments is recorded in the pertinent period according to the lease agreement. However, for leases that provide variable rents, we recognize lease income on a straight-line basis. In addition to a monthly lease rate, some engine leases require an additional rental amount based on the number of hours the engine is used in a particular month. Lease income associated with these contingent rentals is recorded in the period in which actual usage is reported to us by the lessee, which is normally the month following the actual usage. Certain supply chain management programs we provide to our customers contain multiple elements or deliverables, such as program and warehouse management, parts distribution, and maintenance and repair services. We recognize revenue for each element or deliverable that can be identified as a separate unit of accounting at the time of delivery based upon the relative fair value of the products and services. In June 2016, the U.S. Air Force awarded the new contract for the KC-10 Extender Contractor Logistics Support Program ("KC-10 Program") to a competitor. Our principal services under the prior contract for the KC-10 Program were completed in January 2017; however, we have provided limited services since that date. Sales for the KC-10 Program during fiscal 2018, 2017 and 2016 were $29.1 million, $110.6 million, and $148.1 million, respectively. Gross profit for the KC-10 Program during fiscal 2018, 2017 and 2016 was $4.8 million, $8.7 million, and $16.0 million, respectively.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts We maintain an allowance for doubtful accounts to reflect the expected uncollectibility of accounts receivable based on past collection history and specific risks identified among uncollected accounts. In determining the required allowance, we consider factors such as general and industry-specific economic conditions, customer credit history, and our customers' current and expected future financial performance. The majority of our customers are recurring customers with an established payment history. Certain customers are required to undergo an extensive credit check prior to delivery of products or services.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets In accordance with Accounting Standards Codification ("ASC") 350, Intangibles—Goodwill and Other , goodwill and other intangible assets deemed to have indefinite lives are not amortized, but are subject to annual impairment tests. We review and evaluate our goodwill and indefinite life intangible assets for potential impairment at a minimum annually, on May 31, or more frequently if circumstances indicate that impairment is possible. Our annual goodwill impairment test over the last three years has used a combination of the qualitative approach and the two-step quantitative approach to evaluate goodwill for impairment. As of May 31, 2018, we have five reporting units with only four of the reporting units assigned goodwill. Our four reporting units with goodwill include two in our Aviation Services segment (Aviation Supply Chain and Maintenance, Repair, and Overhaul) and two in our Expeditionary Services segment (Airlift and Mobility). We utilized the qualitative assessment approach for all reporting units. We performed the annual qualitative analysis as of May 31, 2018 for the four reporting units with assigned goodwill and concluded it was more likely than not that the fair value of each reporting unit exceeded its carrying value, and thus no impairment charge was recorded. Changes in the carrying amount of goodwill by segment for fiscal 2018 and 2017 are as follows: Aviation Expeditionary Total Balance as of May 31, 2016 $ $ $ Foreign currency translation adjustments ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2017 Acquisition — Foreign currency translation adjustments — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2018 $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Intangible assets with finite useful lives are amortized on a straight-line basis over their estimated useful lives. Intangible assets, other than goodwill, are comprised of the following: May 31, 2018 Gross Accumulated Net Amortizable intangible assets: Customer relationships $ $ ) $ Developed technology ) Lease agreements ) FAA certificate ) Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ) Unamortized intangible assets: Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ May 31, 2017 Gross Accumulated Net Amortizable intangible assets: Customer relationships $ $ ) $ Developed technology ) Lease agreements ) FAA certificate ) Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ) Unamortized intangible assets: Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Customer relationships are being amortized over 10-20 years, developed technology is being amortized over 7-15 years, lease agreements are being amortized over 5-18 years, and the FAA certificate is being amortized over 20 years. Amortization expense recorded during fiscal 2018, 2017 and 2016 was $4.7 million, $4.2 million, and $4.4 million, respectively. The estimated aggregate amount of amortization expense for intangible assets in each of the next five fiscal years is $4.1 million in 2019, $3.7 million in 2020, $3.7 million in 2021, $2.9 million in 2022 and $2.3 million in 2023.
Foreign Currency	Foreign Currency Our foreign subsidiaries utilize the local currency as their functional currency. All balance sheet accounts of foreign subsidiaries transacting business in currencies other than the U.S. dollar are translated at year-end exchange rates. Revenues and expenses are translated at average exchange rates during the year. Translation adjustments are excluded from the results of operations and are recorded in stockholders' equity as a component of accumulated other comprehensive loss until such subsidiaries are liquidated.
Cash	Cash Cash and cash equivalents consist of highly liquid instruments which have original maturities of three months or less when purchased. Restricted cash represents cash on hand required to be set aside by a contractual agreement related to receivable securitization arrangements. Generally, the restrictions related to the receivable securitization arrangements lapse at the time we remit the customer payments collected by us as servicer of previously sold customer receivables to the purchaser.
Financial Instruments and Concentrations of Market or Credit Risk	Financial Instruments and Concentrations of Market or Credit Risk Financial instruments that potentially subject us to concentrations of market or credit risk consist principally of trade receivables. While our trade receivables are diverse and represent a number of entities and geographic regions, the majority are with the U.S. government and its contractors and entities in the aviation industry. Accounts receivable due from the U.S. government were $33.0 million and $29.4 million at May 31, 2018 and 2017, respectively. We perform regular evaluations of customer payment experience, current financial condition, and risk analysis. We may require collateral in the form of security interests in assets, letters of credit, and/or obligation guarantees from financial institutions for transactions executed on other than normal trade terms. The carrying amounts of cash and cash equivalents, accounts receivable, and accounts and trade notes payable approximate fair value because of the short-term maturity of these instruments. The carrying value of long-term debt bearing a variable interest rate approximates fair value. Fair value estimates are made at a specific point in time based on relevant market information about the financial instrument. These estimates are subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. Changes in assumptions could significantly affect the estimates.
Inventories	Inventories Inventories are valued at the lower of cost or market (estimated net realizable value). Cost is determined by the specific identification, average cost, or first-in, first-out methods. From time-to-time, we purchase aircraft and engines for disassembly to individual parts and components. Costs are assigned to these individual parts and components utilizing list prices from original equipment manufacturers and recent sales history. The following is a summary of inventories: May 31, 2018 2017 Aircraft and engine parts, components and finished goods $ $ Raw materials and parts Work-in-process ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Rotable Assets and Equipment under Leases	Rotable Assets and Equipment under Leases Lease revenue is recognized as earned. The cost of the asset under lease is the original purchase price plus overhaul costs. Depreciation is computed using the straight-line method over the estimated service life of the equipment. The balance sheet classification of equipment under lease is generally based on lease term, with fixed-term leases less than twelve months generally classified as short-term and all others generally classified as long-term. Equipment on short-term lease includes aircraft engines and parts on or available for lease to satisfy customers' immediate short-term requirements. The leases are renewable with fixed terms, which generally vary from one to twelve months. Future rent due to us under non-cancelable leases during each of the next five fiscal years is $26.2 million in 2019, $25.7 million in 2020, $25.0 million in 2021, $24.5 million in 2022, and $24.5 million in 2023.
Rotable Assets Supporting Long-term Programs	Rotable Assets Supporting Long-Term Programs Rotable assets supporting long-term programs consists of rotable component parts used to support long-term supply chain programs. The assets are being depreciated on a straight-line basis over their estimated useful lives.
Property, Plant and Equipment	Property, Plant and Equipment We record property, plant and equipment at cost. Depreciation is computed on the straight-line method over useful lives of 10-40 years for buildings and improvements and 3-10 years for equipment, furniture and fixtures, and capitalized software. Leasehold improvements are amortized over the shorter of the estimated useful life or the term of the applicable lease. Repair and maintenance expenditures are expensed as incurred. Upon sale or disposal, cost and accumulated depreciation are removed from the accounts, and related gains and losses are included in results of operations. In accordance with ASC 360, Property, Plant and Equipment , we are required to test for impairment of long-lived assets whenever events or changes in circumstances indicate the carrying value of an asset may not be recoverable from its undiscounted cash flows. We utilize certain assumptions to estimate future undiscounted cash flows, including demand for our services, future market conditions and trends, business development pipeline of opportunities, current and future lease rates, lease terms, and residual values.
Income Taxes	Income Taxes We are subject to income taxes in the U.S., state, and several foreign jurisdictions. In the ordinary course of business, there can be transactions and calculations where the ultimate tax determination is uncertain. We recognize deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns in accordance with applicable accounting guidance for accounting for income taxes, using currently enacted tax rates in effect for the year in which the differences are expected to reverse. We record a valuation allowance when necessary to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets are reduced by a valuation allowance if, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. Both positive and negative evidence are considered in forming our judgment as to whether a valuation allowance is appropriate, and more weight is given to evidence that can be objectively verified. Valuation allowances are reassessed whenever there are changes in circumstances that may cause a change in judgment. The accounting for uncertainty in income taxes requires a more-likely-than-not threshold for financial statement recognition of tax positions taken or expected to be taken in a tax return. Where necessary, we record a liability for the difference between the benefit recognized for financial statement purposes and the tax position taken or expected to be taken on our tax return. To the extent that our assessment of such tax positions changes, the change in estimate is recorded in the period in which the determination is made.
Supplemental Information on Cash Flows	Supplemental Information on Cash Flows Supplemental information on cash flows is as follows: For the Year Ended 2018 2017 2016 Interest paid $ $ $ Income taxes paid Income tax refunds and interest received During fiscal 2018, treasury stock increased $0.9 million reflecting the repurchase of common shares of $13.1 million, restricted stock activity of $1.0 million and the re-issuance of shares upon exercise of stock options, net of shares withheld to satisfy statutory tax obligations, of $11.2 million. During fiscal 2017, treasury stock increased $12.2 million reflecting the repurchase of common shares of $19.8 million, restricted stock grants of $1.3 million and the re-issuance of shares upon exercise of stock options, net of shares withheld to satisfy statutory tax obligations, of $8.9 million. During fiscal 2016, treasury stock increased $21.3 million reflecting the repurchase of common shares of $18.8 million, restricted stock grants of $4.8 million and the re-issuance of shares upon exercise of stock options, net of shares withheld to satisfy statutory tax obligations, of $2.3 million.
Use of Estimates	Use of Estimates We have made estimates and utilized certain assumptions relating to the reporting of assets and liabilities and the disclosures of contingent liabilities to prepare these Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States. Actual results could differ from those estimates.
New Accounting Pronouncements	New Accounting Pronouncements Revenue from Contracts with Customers In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers , which provides guidance for revenue recognition. This ASU affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets. This ASU will supersede the revenue recognition requirements in ASC 605, Revenue Recognition , and most industry-specific guidance. This ASU will also supersede certain cost guidance included in Subtopic 605-35, Revenue Recognition-Construction-Type and Production-Type Contracts . In August 2015, the FASB issued ASU No. 2015-14 which deferred the effective date of the new standard by one year so that it will be effective for us beginning June 1, 2018. We will adopt this ASU using the modified retrospective transition method in the first quarter of fiscal 2019. Under this method, we will be required to recognize the cumulative effect of adopting this ASU as of June 1, 2018. We have substantially completed our assessment of the new ASU and are finalizing the quantification of our adoption adjustments as well as preparing the new required disclosures for the first quarter of fiscal 2019. We have identified three areas where the new ASU will impact our revenue recognition. First, we have certain contracts under which we manufacture products with no alternative use and the Company has an enforceable right to payment from the customer. As a result, the Company will be required to record revenue for these contracts over time as opposed to at the time of shipment which is our current policy today. Second, we have contracts under which we perform repair services on customer-owned assets which will also transition to an over time approach compared to our current policy of recognizing revenue at the time of shipment. Third, we have certain contracts in which revenue is recognized using the percentage of completion method over the expected term of the contract. The new ASU will result in the reduction of the contract term used for revenue recognition as certain contracts include unexercised customer option years or include customer rights to terminate the contract without significant penalty. We expect the cumulative effect for the adoption of the new ASU will result in a decrease to retained earnings of approximately $20 million as of June 1, 2018. We will establish new Contract asset and Contract liability balance sheet accounts and will reclassify certain amounts from Accounts receivable, Inventories, Other non-current assets, and Other liabilities and deferred income into these new accounts. Other New Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases . This ASU amends the existing accounting standards for lease accounting, including requiring lessees to recognize most leases on their balance sheets, including those classified as operating leases under the current accounting guidance. In addition, this ASU will require new qualitative and quantitative disclosures about the Company's leasing activities. This new standard will be effective for us beginning June 1, 2019, with early adoption permitted. This ASU requires a modified retrospective transition approach for all leases existing at, or entered into after, the date of initial application, with an option to use certain transition relief. We are in the preliminary phases of assessing the effect of this ASU on our portfolio of leases. While this assessment continues, we have not yet selected a transition date nor have we determined the effect of this ASU on our consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which amends ASC Topic 718, Compensation—Stock Compensation . This ASU requires excess tax benefits or deficiencies for share-based payments to be recorded in the period shares vest as income tax expense or benefit, rather than within equity. Cash flows related to excess tax benefits are now included in operating activities and are no longer classified as a financing activity. We adopted this ASU on June 1, 2017 and recognized excess tax benefits of $2.9 million as an income tax benefit in fiscal 2018. We have also presented the excess tax benefits within operating activities in the consolidated statement of cash flows for fiscal 2018. As permitted, we adopted the statement of cash flow presentation guidance on a prospective basis with no adjustments to the previously reported amounts. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash . This ASU requires restricted cash to be included within beginning and ending total cash amounts reported in the consolidated statements of cash flows as well as increased disclosure requirements. As permitted, we have early adopted this ASU in fiscal 2018. The ASU is required to be adopted on a retroactive basis; however, we did not have restricted cash in our prior periods reported. In February 2018, the FASB issued ASU 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . This ASU permits the reclassification of tax effects stranded in accumulated other comprehensive income to retained earnings as a result of the Tax Cuts and Jobs Act (the "Tax Reform Act"). This new standard will be effective for us beginning June 1, 2019 with early adoption permitted. We are currently evaluating the impact of this new standard on our consolidated financial statements. In March 2017, the FASB issued ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . This ASU requires an employer to report the service cost component of net periodic pension benefit cost in the same line item as other compensation costs for those related employees. Other components of net pension cost, including interest, expected return on plan assets, and actuarial gains and losses are to be presented outside of operating income. This new standard requires retrospective treatment for the classification of pension costs and will be effective for us beginning June 1, 2018. With the majority of our pension plans frozen and total service cost, including administrative expenses, of $2.4 million and $2.5 million in fiscal 2018 and 2017, respectively, this ASU is not expected to have a material impact on our consolidated financial statements.

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	May 31, 2018
Summary of Significant Accounting Policies
Schedule of goodwill by reportable segment	Aviation Expeditionary Total Balance as of May 31, 2016 $ $ $ Foreign currency translation adjustments ) — ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2017 Acquisition — Foreign currency translation adjustments — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2018 $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of intangible assets, other than goodwill	May 31, 2018 Gross Accumulated Net Amortizable intangible assets: Customer relationships $ $ ) $ Developed technology ) Lease agreements ) FAA certificate ) Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ) Unamortized intangible assets: Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ May 31, 2017 Gross Accumulated Net Amortizable intangible assets: Customer relationships $ $ ) $ Developed technology ) Lease agreements ) FAA certificate ) Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ) Unamortized intangible assets: Trademarks — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Summary of inventories	May 31, 2018 2017 Aircraft and engine parts, components and finished goods $ $ Raw materials and parts Work-in-process ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of supplemental information on cash flows	For the Year Ended 2018 2017 2016 Interest paid $ $ $ Income taxes paid Income tax refunds and interest received

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	May 31, 2018
Discontinued Operations
Schedule of operating results for discontinued operations	For the Year Ended May 31, 2018 2017 2016 Sales $ $ $ Cost of sales ) ) ) Asset impairments ) — — Selling, general and administrative expenses ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating loss from discontinued operations ) ) ) Gain on sale of Telair Cargo Group — — Provision for income taxes (benefit) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income (Loss) from discontinued operations $ ) $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of carrying amounts of the major classes and liabilities for our discontinued operations	May 31, 2018 2017 Inventory, rotable assets, and equipment $ $ Accounts receivable, net Goodwill — Other assets ​ ​ ​ ​ ​ ​ ​ ​ Assets of discontinued operations $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities—current $ $ Liabilities—non-current — ​ ​ ​ ​ ​ ​ ​ ​ Liabilities of discontinued operations $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Financing Arrangements (Tables)

Financing Arrangements (Tables)	12 Months Ended
	May 31, 2018
Financing Arrangements
Summary of carrying amount of debt	May 31, 2018 2017 Revolving Credit Facility expiring November 1, 2021 with interest payable monthly $ $ Term loan due November 1, 2021 with interest payable monthly — Industrial revenue bond (secured by property, plant and equipment) due August 1, 2018 with interest payable monthly Capital lease obligations — ​ ​ ​ ​ ​ ​ ​ ​ Total debt Current maturities of debt — ) Debt issuance costs, net ) ) ​ ​ ​ ​ ​ ​ ​ ​ Long-term debt $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of borrowing activity under the Credit Agreement	For the Year Ended May 31, 2018 2017 2016 Maximum amount borrowed $ $ $ Average daily borrowings Average interest rate during the year % % %

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	May 31, 2018
Stock-Based Compensation
Schedule of assumptions used in the Black-Scholes option pricing model to estimate the fair value of stock option grant	Stock Options Granted 2018 2017 2016 Risk-free interest rate % % % Expected volatility of common stock % % % Dividend yield % % % Expected option term in years
Summary of stock option activity	A summary of stock option activity for the three years ended May 31, 2018 consisted of the following (shares in thousands): 2018 2017 2016 Shares Weighted Shares Weighted Shares Weighted Outstanding at beginning of year $ $ $ Granted $ $ $ Exercised ) $ ) $ ) $ Cancelled ) $ ) $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Outstanding at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options exercisable at end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of additional information regarding stock options outstanding	The following table provides additional information regarding stock options outstanding as of May 31, 2018 (shares in thousands): Options Outstanding Options Exercisable Option Number Weighted-Average Weighted- Number Weighted- $12.00 - $20.00 $ $ $20.01 - $26.00 $ $ $26.01 - $38.70 $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of restricted share activity	Restricted share activity during the fiscal year ended May 31, 2018 was as follows (shares in thousands): Number of Weighted Average Nonvested at May 31, 2017 $ Granted $ Vested ) $ Forfeited ) $ ​ ​ ​ ​ ​ ​ ​ ​ Nonvested at May 31, 2018 $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	May 31, 2018
Income Taxes
Schedule of components of provision for income tax on income from continuing operations	For the Year Ended 2018 2017 2016 Current: Federal $ $ $ State Foreign ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate	For the Year Ended 2018 2017 2016 Provision for income tax (benefit) at the federal statutory rate $ $ $ Deferred tax re-measurement from the Tax Reform Act ) — — Excess tax benefits from stock-based compensation ) — — State net operating losses Change in valuation allowance for state deferred tax assets ) ) ) Prior period adjustments — — ) Effective settlement of prior tax position — ) — Other ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provision for income tax $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of income before provision for income taxes	For the Year Ended 2018 2017 2016 Domestic $ $ $ Foreign ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of components of deferred tax liabilities and assets	May 31, 2018 2017 Deferred tax assets: Inventory costs $ $ Impairments Postretirement benefits Employee benefits State net operating losses Other ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax assets Valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax assets net of valuation allowance ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: Tangible and intangible assets ) ) Other ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax liabilities ) ) ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax liabilities $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Reconciliation of unrecognized tax benefits	For the Year Ended 2018 2017 2016 Balance, beginning of year $ $ $ Additions for tax positions of prior years — Effective settlement of prior tax position — ) — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	May 31, 2018
Earnings Per Share
Schedule of reconciliation of computations of basic and diluted earnings per share information	The following tables provide a reconciliation of the computations of basic and diluted earnings per share information for each of the years in the three-year period ended May 31, 2018 (shares in millions). For the Year Ended 2018 2017 2016 Basic and Diluted EPS: Income from continuing operations $ $ $ Less income attributable to participating shares ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income from continuing operations attributable to common shareholders Income (Loss) from discontinued operations attributable to common shareholders ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income attributable to common shareholders for earnings per share $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average common shares outstanding—basic Additional shares from assumed exercise of stock options ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average common shares outstanding—diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share—basic: Earnings from continuing operations $ $ $ Earnings (Loss) from discontinued operations ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share—basic $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share—diluted: Earnings from continuing operations $ $ $ Earnings (Loss) from discontinued operations ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Earnings per share—diluted $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	May 31, 2018
Employee Benefit Plans
Schedule of change to the entity's projected benefit obligation and the fair value of plan assets for pension plans	May 31, 2018 2017 Change in projected benefit obligation: Projected benefit obligation at beginning of year $ $ Service cost Interest cost Participant contributions Net actuarial gain ) ) Benefits and administrative payments ) ) Plan change — Foreign currency translation adjustment ​ ​ ​ ​ ​ ​ ​ ​ Projected benefit obligation at end of year $ $ ​ ​ ​ ​ ​ ​ ​ ​ Change in the fair value of plan assets: Fair value of plan assets at beginning of year $ $ Actual return on plan assets Employer contributions Participant contributions Benefits and administrative payments ) ) Foreign currency translation adjustment ​ ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at end of year $ $ ​ ​ ​ ​ ​ ​ ​ ​ Funded status at end of year $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of amounts recognized in the Consolidated Balance Sheets	May 31, 2018 2017 Non-current assets $ $ — Accrued liabilities ) ) Other liabilities and deferred income ) ) ​ ​ ​ ​ ​ ​ ​ ​ Funded status at end of year $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of amounts recognized in accumulated other comprehensive loss	May 31, 2018 2017 Actuarial loss $ $ Prior service credit ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of components of pension expense charged to the consolidated statement of income	For the Year Ended 2018 2017 2016 Service cost $ $ $ Interest cost Expected return on plan assets ) ) ) Curtailment — — Amortization of prior service cost — — Recognized net actuarial loss ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of estimated amounts for plans that will be amortized from accumulated other comprehensive loss into expense over the next fiscal year	Net actuarial loss $ Prior service cost — ​ ​ ​ ​ ​ Total $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of key weighted-average assumptions used in the measurement of the entity's projected benefit obligations	May 31, 2018 2017 Discount rate: Domestic plans % % International plan Rate of compensation increase: Domestic plans n/a % International plans %
Summary of the weighted average assumptions used to determine net periodic pension expense	For the Year Ended 2018 2017 2016 Discount rate: Domestic plans % % % International plan Rate of compensation increase: Domestic plans % % % International plan Expected long-term rate on plan assets: Domestic plans % % % International plan
Schedule of actual asset allocation and target allocations	May 31, Target Asset 2018 2017 Equity securities % % 45 - 75 % Fixed income securities 15 - 45 % Other 0 - 25 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ % % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of fair value of pension plan assets	The following table sets forth by level, within the fair value hierarchy, pension plan assets at their fair value as of May 31, 2018: Level 1 1 Level 2 2 Level 3 3 Total Equity securities: U.S. mutual funds $ $ — $ — $ International mutual funds — — Fixed income: Government securities and corporate bond mutual funds — — Funds-of-funds — Hedge funds — — Insurance annuities — — Cash and cash equivalents — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following table sets forth by level, within the fair value hierarchy, pension plan assets at their fair value as of May 31, 2017: Level 1 1 Level 2 2 Level 3 3 Total Equity securities: U.S. mutual funds $ $ — $ — $ International mutual funds — — Fixed income: Government securities and corporate bond mutual funds — — Funds-of-funds — Hedge funds — — Cash and cash equivalents — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total investments $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1 Quoted prices in active markets for identical assets that we have the ability to access as of the reporting date. 2 Inputs other than quoted prices included within Level 1 that are directly observable for the asset or indirectly observable through corroboration with observable market data. 3 Unobservable inputs, such as internally developed pricing models or third party valuations for the asset due to little or no market activity for the asset.
Schedule of reconciliation of Level 3 pension assets measured at fair value	Hedge Funds Fund-of-funds Insurance Annuities Total Balance as of May 31, 2016 $ $ $ — $ Sales — ) — ) Return on plan assets related to assets still held at May 31, 2017 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2017 — Purchases — — Sales ) — — ) Return on plan assets related to assets still held at May 31, 2018 — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2018 $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Summary of estimated future pension payments	Fiscal Year 2019 2020 2021 2022 2023 2024 to Estimated future pension payments $ $ $ $ $ $

Accumulated Other Comprehensi33

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	May 31, 2018
Accumulated Other Comprehensive Loss
Schedule of changes in accumulated other comprehensive loss ("AOCL") by component	Currency Pension Total Balance as of June 1, 2015 $ $ ) $ ) Reclassifications within AOCL ) — Other comprehensive loss before reclassifications — ) ) Amounts reclassified from AOCL — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive loss — ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2016 ) ) ) Other comprehensive income (loss) before reclassifications ) Amounts reclassified from AOCL — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive income (loss) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2017 ) ) ) Other comprehensive income before reclassifications Amounts reclassified from AOCL — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other comprehensive income ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance as of May 31, 2018 $ $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	May 31, 2018
Commitments and Contingencies
Schedule of future minimum payments under operating leases	2019 $ 2020 2021 2022 2023 2024 and thereafter

Other Noncurrent Assets (Tables

Other Noncurrent Assets (Tables)	12 Months Ended
	May 31, 2018
Other Noncurrent Assets
Schedule of other noncurrent assets	May 31, 2018 2017 Costs in excess of billings $ $ Assets under deferred compensation plan Cash surrender value of life insurance License fees Investments in joint ventures Other ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	May 31, 2018
MRO facilities acquired in Quebec and Ontario, Canada owned by Premier Aviation
Acquisition of Premier Aviation
Schedule of fair value of net assets acquired	Current assets $ Property and equipment Intangible assets, including goodwill Accounts payable and accrued liabilities ) ​ ​ ​ ​ ​ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
ACLAS
Acquisition of Premier Aviation
Schedule of fair value of net assets acquired	Inventory $ Equipment on or available for long-term lease Intangible assets ​ ​ ​ ​ ​ Assets acquired $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Vantem Modular LLC
Acquisition of Premier Aviation
Schedule of fair value of net assets acquired	Current assets $ Equipment Intangible assets Contingent consideration ) ​ ​ ​ ​ ​ Net assets acquired Goodwill ​ ​ ​ ​ ​ Purchase price $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Business Segment Information (T

Business Segment Information (Tables)	12 Months Ended
	May 31, 2018
Business Segment Information
Schedule of selected financial information for each reportable segment	For the Year Ended May 31, 2018 2017 2016 Net sales: Aviation Services $ $ $ Expeditionary Services ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year Ended May 31, 2018 2017 2016 Gross profit: Aviation Services $ $ $ Expeditionary Services ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ May 31, 2018 2017 Total assets: Aviation Services $ $ Expeditionary Services Corporate and discontinued operations ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year Ended May 31, 2018 2017 2016 Capital expenditures: Aviation Services $ $ $ Expeditionary Services Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total continuing operations Discontinued operations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year Ended May 31, 2018 2017 2016 Depreciation and amortization: 1 Aviation Services $ $ $ Expeditionary Services Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total continuing operations Discontinued operations ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1 Includes depreciation and amortization of stock-based compensation.
Schedule of reconciliation of segment gross profit to income from continuing operations before provision for income taxes	For the Year Ended May 31, 2018 2017 2016 Segment gross profit $ $ $ Selling, general and administrative ) ) ) Other expenses ) — ) Interest expense ) ) ) Interest income ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Income from continuing operations before provision for income taxes $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of sales to the U.S. Department of Defense, other U.S. government agencies and their contractors by segment	For the Year Ended May 31, 2018 2017 2016 Aviation Services $ $ $ Expeditionary Services ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Percentage of total sales % % % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of sales by type of product/service	For the Year Ended May 31, 2018 2017 2016 Aviation supply chain $ $ $ Maintenance, repair and overhaul services Mobility products Airlift — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of geographic data	May 31, 2018 2017 Long-lived assets: United States $ $ Europe Other ​ ​ ​ ​ ​ ​ ​ ​ Total continuing operations Discontinued operations — ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Selected Quarterly Data (Unau38

Selected Quarterly Data (Unaudited) (Tables)	12 Months Ended
	May 31, 2018
Selected Quarterly Data (Unaudited)
Schedule of unaudited selected quarterly data	Fiscal 2018 First Second Third Fourth Full Sales $ $ $ $ $ Gross profit Income from continuing operations Loss from discontinued operations 1 ) ) ) ) ) Net income (loss) ) Earnings (Loss) per share—basic: 2 Continuing operations Discontinued operations ) ) ) ) ) Earnings per share—basic ) Earnings (Loss) per share—diluted: 2 Continuing operations Discontinued operations ) ) ) ) ) Earnings per share—diluted ) Fiscal 2017 First Second Third Fourth Full Sales $ $ $ $ $ Gross profit Income from continuing operations Income (Loss) from discontinued operations ) ) Net income Earnings (Loss) per share—basic: 2 Continuing operations Discontinued operations ) ) Earnings per share—basic Earnings (Loss) per share—diluted: 2 Continuing operations Discontinued operations ) ) Earnings per share—diluted 1 Loss from discontinued operations in fiscal 2018 includes pre-tax aircraft and other asset impairment charges of $54.2 million in the second quarter and a goodwill impairment charge of $9.8 million in the third quarter. 2 The earnings-per-share computation for the year is a separate, annual calculation. Accordingly, the sum of the quarterly earnings-per-share amounts does not necessarily equal the earnings per share for the year.

Allowance for Doubtful Accoun39

Allowance for Doubtful Accounts (Tables)	12 Months Ended
	May 31, 2018
Allowance for Doubtful Accounts
Schedule of allowance for doubtful accounts	May 31, 2018 2017 2016 Balance, beginning of year $ $ $ Provision charged to operations Recoveries, deductions for accounts written off and other reclassifications ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance, end of year $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Revenue Recognition
Recognized net favorable cumulative catch-up adjustments	$ 3.6	$ 8.5	$ 3.7
KC10 logistics support services
Revenue Recognition
Sales for KC10 logistics support services	29.1	110.6	148.1
Gross profit recognized for KC10 logistics support services	$ 4.8	$ 8.7	$ 16
Minimum
Principles of Consolidation
Percentage of owned aircraft	20.00%
Maximum
Principles of Consolidation
Percentage of owned aircraft	50.00%

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Goodwill (Details) $ in Millions	12 Months Ended
	May 31, 2018USD ($)item	May 31, 2017USD ($)
Goodwill by reportable segment
Total number of reporting units | item	5
Number of reporting units assigned for goodwill | item	4
Goodwill, Beginning Balance	$ 105.6	$ 107.5
Acquisition	12.5
Foreign currency translation adjustments	0.6	(1.9)
Goodwill, Ending Balance	$ 118.7	105.6
Aviation Services
Goodwill by reportable segment
Number of reporting units assigned for goodwill | item	2
Goodwill, Beginning Balance	$ 64.4	66.3
Acquisition	12.5
Foreign currency translation adjustments	0.6	(1.9)
Goodwill, Ending Balance	$ 77.5	64.4
Expeditionary Services
Goodwill by reportable segment
Number of reporting units assigned for goodwill | item	2
Goodwill, Beginning Balance	$ 41.2	41.2
Goodwill, Ending Balance	$ 41.2	$ 41.2

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Intangibles (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Amortizable intangible assets:
Gross carrying amount	$ 60	$ 57.8
Accumulated Amortization	(33.3)	(28.3)
Net carrying amount	26.7	29.5
Unamortized intangible assets:
Trademarks	1.1	1.1
Intangible Assets, Gross (Excluding Goodwill)	61.1	58.9
Intangible Assets, Net (Excluding Goodwill), Total	27.8	30.6
Amortization expense	4.7	4.2	$ 4.4
Estimated aggregate amortization expense for intangible assets in each of the next five fiscal years
2,019	4.1
2,020	3.7
2,021	3.7
2,022	2.9
2,023	2.3
Customer relationships
Amortizable intangible assets:
Gross carrying amount	26.3	24.4
Accumulated Amortization	(13.9)	(11.6)
Net carrying amount	12.4	12.8
Developed technology
Amortizable intangible assets:
Gross carrying amount	9.1	8.8
Accumulated Amortization	(5.9)	(4.7)
Net carrying amount	3.2	4.1
Lease agreements
Amortizable intangible assets:
Gross carrying amount	22.5	22.5
Accumulated Amortization	(12.6)	(11.2)
Net carrying amount	9.9	11.3
FAA certificate
Amortizable intangible assets:
Gross carrying amount	1.9	1.9
Accumulated Amortization	(0.9)	(0.8)
Net carrying amount	$ 1	1.1
Unamortized intangible assets:
Useful life	20 years
Trademarks
Amortizable intangible assets:
Gross carrying amount	$ 0.2	0.2
Net carrying amount	$ 0.2	$ 0.2
Minimum | Customer relationships
Unamortized intangible assets:
Useful life	10 years
Minimum | Developed technology
Unamortized intangible assets:
Useful life	7 years
Minimum | Lease agreements
Unamortized intangible assets:
Useful life	5 years
Maximum | Customer relationships
Unamortized intangible assets:
Useful life	20 years
Maximum | Developed technology
Unamortized intangible assets:
Useful life	15 years
Maximum | Lease agreements
Unamortized intangible assets:
Useful life	18 years

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Financial Instruments (Details) - USD ($) $ in Millions	May 31, 2018	May 31, 2017
Accounts receivable | Customer | U.S. Government
Financial Instruments and Concentrations of Market or Credit Risk
Accounts receivable due	$ 33	$ 29.4

Summary of Significant Accoun44

Summary of Significant Accounting Policies - Inventory (Details) - USD ($) $ in Millions	May 31, 2018	May 31, 2017
Inventories
Aircraft and engine parts, components and finished goods	$ 383.5	$ 362.6
Raw materials and parts	45.1	45
Work-in-process	32.1	25.8
Total inventories	$ 460.7	$ 433.4

Summary of Significant Accoun45

Summary of Significant Accounting Policies - Rotable Assets and Equipment under Leases (Details) $ in Millions	12 Months Ended
	May 31, 2018USD ($)
Future rent due to us under non-cancelable leases
2,019	$ 26.2
2,020	25.7
2,021	25
2,022	24.5
2,023	$ 24.5
Minimum
Rotable Assets and Equipment under leases
Period of short-term leases	1 month
Maximum
Rotable Assets and Equipment under leases
Period of short-term leases	12 months

Summary of Significant Accoun46

Summary of Significant Accounting Policies - Property, Plant and Equipment and Supplemental Information on Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Supplemental Information on Cash Flows
Interest paid	$ 7.2	$ 4.4	$ 4.7
Income taxes paid	17	12.7	35.7
Income tax refunds and interest received	$ 0.1	$ 1.3	$ 1.3
Building and improvements | Minimum
Property, Plant and Equipment
Useful life	10 years
Building and improvements | Maximum
Property, Plant and Equipment
Useful life	40 years
Equipment | Minimum
Property, Plant and Equipment
Useful life	3 years
Equipment | Maximum
Property, Plant and Equipment
Useful life	10 years
Furniture and fixtures | Minimum
Property, Plant and Equipment
Useful life	3 years
Furniture and fixtures | Maximum
Property, Plant and Equipment
Useful life	10 years
Capitalized software | Minimum
Property, Plant and Equipment
Useful life	3 years
Capitalized software | Maximum
Property, Plant and Equipment
Useful life	10 years

Summary of Significant Accoun47

Summary of Significant Accounting Policies - Treasury Stock (Details) - Treasury Stock - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Total increase in treasury stock	$ 0.9	$ 12.2	$ 21.3
Repurchase of treasury shares	13.1	19.8	18.8
Change in treasury stock due to restricted stock grants	(1)	(1.3)	(4.8)
Change in treasury stock due to exercise of stock options, net of shares withheld to satisfy statutory tax obligations	$ 11.2	$ 8.9	$ 2.3

Summary of Significant Accoun48

Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016	Jun. 01, 2018
New Accounting Pronouncements
Retained earnings	$ 733.2	$ 727.9
Amount of recognized excess tax benefits as a reduction to income tax benefit	3.5	25.1	$ 23.4
Defined Benefit Pension Plans
New Accounting Pronouncements
Majority of our pension plans frozen and total service cost, including administrative expenses	2.4	$ 2.5
Improvements to Employee Share-Based Payment Accounting
New Accounting Pronouncements
Amount of recognized excess tax benefits as a reduction to income tax benefit	$ (2.9)
ASU 2014-09 | Adjustment
New Accounting Pronouncements
Retained earnings				$ (20)

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended										12 Months Ended
	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	Feb. 29, 2016	Aug. 31, 2015	May 31, 2018	May 31, 2017	May 31, 2016
Discontinued Operations
Liabilities of discontinued operations	$ 25				$ 33.4						$ 25	$ 33.4
Interest expense											8	5.3	$ 6.4
Operating results for discontinued operations
Sales											96.3	176.9	184.9
Cost of sales											(101.4)	(165.1)	(184.2)
Asset impairments											(65.2)
Selling, general and administrative expenses											(11.8)	(16.1)	(18.5)
Operating loss from discontinued operations											(82.1)	(4.3)	(17.8)
Provision for income taxes (benefit)					(6.7)				$ 2.8		(24)	(8.8)	7.7
Income (Loss) from discontinued operations	(6.1)	$ (15.8)	$ (35.8)	$ (0.4)	4.9	$ (0.7)	$ 2.4	$ (2.1)			(58.1)	4.5	2.2
Carrying amounts of the major classes of assets and liabilities for our discontinued operations
Inventory, rotable assets, and equipment	106.1				183.7						106.1	183.7
Accounts receivable, net	14.7				17						14.7	17
Goodwill					9.8							9.8
Other assets	4.2				7.7						4.2	7.7
Assets of discontinued operations	125				218.2						125	218.2
Liabilities - current	25				30.8						25	30.8
Liabilities - non-current					2.6							2.6
Liabilities of discontinued operations	$ 25				$ 33.4						25	33.4
Telair Cargo Group | A400M | Discontinued Operations, Held-for-sale or Disposed of by Sale
Operating results for discontinued operations
Gain recognized on sale of business													27.7
Telair Cargo Group | A400M | Disposed of by sale
Operating results for discontinued operations
Gain recognized on sale of business										$ 27.7
Contractor-Owned, Contractor-Operated | Discontinued Operations, Held-for-sale or Disposed of by Sale
Discontinued Operations
Goodwill impairment charge		$ 9.8
Impairment and other charges			$ 54.2
General corporate overhead											0	0	0
Interest expense											$ 0	$ 0	$ 0

Sale of Receivables (Details)

Sale of Receivables (Details) - Purchase Agreement - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	Feb. 23, 2018
Sale of Receivables
Retained interests	$ 0
Sale of Receivables	239.6
Amount remitted to the Purchaser	167.9
Amount collected	10.5
Maximum
Sale of Receivables
Sale of Receivables		$ 150
Other Expense
Sale of Receivables
Purchase discount and other fees	$ 0.9

Financing Arrangements (Details

Financing Arrangements (Details) $ in Millions	Oct. 18, 2017USD ($)facility	Sep. 19, 2017facility	May 31, 2018USD ($)	May 31, 2017USD ($)	May 31, 2016USD ($)	Mar. 24, 2015USD ($)
Financing Arrangements
Total debt			$ 178.9	$ 156.2
Current maturities of debt				(0.1)
Debt issuance costs, net			(1.7)	(2)
Long-term debt			177.2	154.1
CDOR | Minimum
Financing Arrangements
Basis spread on variable rate (as a percent)	1.25%
CDOR | Maximum
Financing Arrangements
Basis spread on variable rate (as a percent)	2.25%
Prime Rate | Minimum
Financing Arrangements
Basis spread on variable rate (as a percent)	0.25%
Prime Rate | Maximum
Financing Arrangements
Basis spread on variable rate (as a percent)	1.25%
Credit Facility Amendment
Financing Arrangements
Maximum borrowing capacity						$ 500
Term loan due November 1, 2021 with interest payable monthly
Financing Arrangements
Total debt			23.9
Maximum borrowing capacity	$ 31
Capital lease obligations
Financing Arrangements
Total debt				0.2
MRO facilities acquired in Canada owned by Premier Aviation
Financing Arrangements
Number of facilities acquired | facility	2	2
Revolving Credit Facility expiring November 1, 2021 with interest payable monthly
Financing Arrangements
Total debt			$ 130	131
Revolving Credit Facility expiring November 1, 2021 with interest payable monthly | Eurodollar rate | Minimum
Financing Arrangements
Basis spread on variable rate under the credit agreement after amendment (as a percent)			1.00%
Revolving Credit Facility expiring November 1, 2021 with interest payable monthly | Eurodollar rate | Maximum
Financing Arrangements
Basis spread on variable rate under the credit agreement after amendment (as a percent)			2.00%
Revolving Credit Facility expiring November 1, 2021 with interest payable monthly | Base rate | Minimum
Financing Arrangements
Basis spread on variable rate under the credit agreement after amendment (as a percent)			0.00%
Revolving Credit Facility expiring November 1, 2021 with interest payable monthly | Base rate | Maximum
Financing Arrangements
Basis spread on variable rate under the credit agreement after amendment (as a percent)			1.00%
Industrial revenue bond (secured by property, plant and equipment) due August 1, 2018 with interest payable monthly
Financing Arrangements
Total debt			$ 25	25
Revolving credit facility | Credit Facility Amendment
Financing Arrangements
Increase in borrowing capacity			250
Total borrowing capacity			750
Credit Agreement and its Predecessor
Short-term borrowing activity
Maximum amount borrowed			275	217	$ 200
Average daily borrowings			$ 214.1	$ 175.5	$ 134.2
Average interest rate during the year (as a percent)			2.52%	1.77%	1.41%
Secured credit facility (secured by aircraft and related engines and components) due April 23, 2015 with floating interest rate, payable monthly
Short-term borrowing activity
Amount outstanding			$ 9.9

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) $ / shares in Units, $ in Millions	12 Months Ended
	May 31, 2018USD ($)item$ / sharesshares	May 31, 2017USD ($)$ / sharesshares	May 31, 2016USD ($)$ / sharesshares
Stock-Based Compensation
Total number of shares granted since inception	11,149,000
2013 Stock Plan
Stock-Based Compensation
Shares available for future grant	2,128,238
Stock options
Stock-Based Compensation
Expiration term	10 years
First number of equal annual increments in which stock options are exercisable | item	3
First number of equal annual increments in which stock options are exercisable | item	4
First number of equal annual increments in which stock options are exercisable | item	5
Commencement period after the date of grant for annual increments of stock options becoming exercisable	1 year
Weighted average fair value of stock options granted (in dollars per share) | $ / shares	$ 9.29	$ 6.50	$ 7.48
Assumptions used in the Black-Scholes option pricing models to estimate the fair value of each stock option grant
Risk-free interest rate	1.80%	1.00%	1.60%
Expected volatility of common stock	31.70%	36.80%	36.10%
Dividend yield	0.90%	1.30%	1.10%
Expected option term in years	4 years 3 months 18 days	4 years	4 years 2 months 12 days
Shares
Outstanding at beginning of year (in shares)	2,334,000	2,096,000	1,857,000
Granted (in shares)	463,140	687,000	488,767
Exercised (in shares)	(704,000)	(396,000)	(122,000)
Cancelled (in shares)	(11,000)	(53,000)	(128,000)
Outstanding at end of year (in shares)	2,082,000	2,334,000	2,096,000
Options exercisable at end of year (in shares)	883,000	910,000	837,000
Weighted Average Exercise Price
Outstanding at beginning of year (in dollars per share) | $ / shares	$ 23.02	$ 22.17	$ 21.05
Granted (in dollars per share) | $ / shares	35.33	24.10	26.62
Exercised (in dollars per share) | $ / shares	20.04	20.07	20.61
Cancelled (in dollars per share) | $ / shares	29.50	25.42	24.47
Outstanding at end of year (in dollars per share) | $ / shares	26.72	23.02	22.17
Options exercisable at end of year (in dollars per share) | $ / shares	$ 23.81	$ 21.97	$ 21.21
Stock options, additional disclosures
Total fair value of stock options vested | $	$ 4.9	$ 3.5	$ 2.7
Total intrinsic value of stock options exercised | $	14.2	4.7	1
Aggregate intrinsic value of options outstanding | $	37.4	27.8
Tax benefit realized from stock options exercised | $	2.9	1.2	0.2
Unearned compensation not yet recognized | $	$ 4.6
Average remaining amortization period of unearned compensation	8 months 12 days
Stock options | Selling, general and administrative expenses
Stock options, additional disclosures
Compensation expense | $	$ 5.1	4.6	3.5
Restricted stock
Stock-Based Compensation
Granted (in shares)	188,000
Stock options, additional disclosures
Unearned compensation not yet recognized | $	$ 4.1
Average remaining amortization period of unearned compensation	2 years 6 months
Restricted stock | Selling, general and administrative expenses
Stock options, additional disclosures
Compensation expense | $	$ 10.2	$ 6.4	$ 3.2
Restricted stock | 2013 Stock Plan
Stock-Based Compensation
Granted (in shares)	2,669,000
Restricted stock | Minimum
Stock-Based Compensation
Vesting period	1 year
Restricted stock | Maximum
Stock-Based Compensation
Vesting period	5 years
Performance-based restricted stock | Minimum
Stock-Based Compensation
Vesting period	3 years
Performance-based restricted stock | Maximum
Stock-Based Compensation
Vesting period	5 years
Time-based restricted stock | Board of Directors
Stock-Based Compensation
Granted (in shares)	55,000	50,625	47,083

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options (Details) shares in Thousands	12 Months Ended
	May 31, 2018$ / sharesshares
Options Outstanding
Number Outstanding at the end of the period (in shares) | shares	2,082
Weighted-Average Remaining Contractual Life in Years	7 years
Weighted-Average Exercise Price (in dollars per Share)	$ 26.72
Options Exercisable
Number Outstanding at the end of the period (in shares) | shares	883
Weighted-Average Exercise Price (in dollar per Share)	$ 23.81
$12.00 - $20.00
Share-Based Compensation
Option Exercise Price Range, low end of range (in dollars per share)	12
Option Exercise Price Range, high end of range (in dollars per share)	$ 20
Options Outstanding
Number Outstanding at the end of the period (in shares) | shares	160
Weighted-Average Remaining Contractual Life in Years	3 years 2 months 12 days
Weighted-Average Exercise Price (in dollars per Share)	$ 14.51
Options Exercisable
Number Outstanding at the end of the period (in shares) | shares	160
Weighted-Average Exercise Price (in dollar per Share)	$ 14.51
$20.01 - $26.00
Share-Based Compensation
Option Exercise Price Range, low end of range (in dollars per share)	20.01
Option Exercise Price Range, high end of range (in dollars per share)	$ 26
Options Outstanding
Number Outstanding at the end of the period (in shares) | shares	1,041
Weighted-Average Remaining Contractual Life in Years	6 years 9 months 18 days
Weighted-Average Exercise Price (in dollars per Share)	$ 24.63
Options Exercisable
Number Outstanding at the end of the period (in shares) | shares	447
Weighted-Average Exercise Price (in dollar per Share)	$ 24.93
$26.01 - $38.70
Share-Based Compensation
Option Exercise Price Range, low end of range (in dollars per share)	26.01
Option Exercise Price Range, high end of range (in dollars per share)	$ 38.70
Options Outstanding
Number Outstanding at the end of the period (in shares) | shares	881
Weighted-Average Remaining Contractual Life in Years	7 years 10 months 24 days
Weighted-Average Exercise Price (in dollars per Share)	$ 31.41
Options Exercisable
Number Outstanding at the end of the period (in shares) | shares	276
Weighted-Average Exercise Price (in dollar per Share)	$ 27.37

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Restricted stock
Number of Shares
Nonvested at the beginning of the period ( in shares)	595,000
Granted (in shares)	188,000
Vested (in shares)	(91,000)
Forfeited (in shares)	(8,000)
Nonvested at the end of the period (in shares)	684,000	595,000
Weighted Average Fair Value on Grant Date
Nonvested at the beginning of the period (in dollars per share)	$ 25.93
Granted (in dollars per share)	35.35
Vested (in dollars per share)	25.08
Forfeited (in dollars per share)	26.43
Nonvested at the end of the period (in dollars per share)	$ 27.89	$ 25.93
Unearned compensation not yet recognized	$ 4.1
Average remaining amortization period of unearned compensation	2 years 6 months
Restricted stock | Selling, general and administrative expenses
Restricted Stock
Compensation expense	$ 10.2	$ 6.4	$ 3.2
Performance-based restricted stock | Executives and other key employees
Number of Shares
Granted (in shares)	108,440	212,583	119,929
Time-based restricted stock | Board of Directors
Number of Shares
Granted (in shares)	55,000	50,625	47,083
Time-based restricted stock | Executives and other key employees
Number of Shares
Granted (in shares)	24,425	39,100	42,557

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended				5 Months Ended	7 Months Ended	12 Months Ended
	May 31, 2018	Feb. 28, 2018	May 31, 2017	Feb. 29, 2016	May 31, 2018	Dec. 31, 2017	May 31, 2018	May 31, 2017	May 31, 2016
Current:
U.S. federal statutory income tax rate (as a percent)					21.00%	35.00%	29.20%	35.00%	35.00%
Income tax benefit for the re-measurement impact	$ 1.1	$ 13					$ 14.1
Federal							14.6	$ 9.3	$ 13.7
State							0.1	0.2	0.4
Foreign							1.7	3.1	3.8
Total current							16.4	12.6	17.9
Deferred							(12.9)	12.5	5.5
Provision for income tax (benefit)							3.5	25.1	23.4
Reasons for difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate
Provision for income tax (benefit) at the federal statutory rate							22.5	27	24.1
Deferred tax re-measurement from the Tax Reform Act							(14.1)
Excess tax benefits from stock-based compensation							(2.9)
State net operating losses							1.3	5.7	1.1
Change in valuation allowance for state deferred tax assets							(3.4)	(5.7)	(1.1)
Prior period adjustments									(1.3)
Effective settlement of prior tax position								(2.2)
Other							0.1	0.3	0.6
Provision for income tax (benefit)							3.5	25.1	23.4
Income tax expense in discontinued operations			$ (6.7)	$ 2.8			(24)	(8.8)	7.7
Income tax benefit from continued operations							3.5	25.1	23.4
Income before provision for income taxes							77.2	77.1	68.9
Deferred tax assets:
Inventory costs	15.9		21.3		$ 15.9		15.9	21.3
Impairments	2.1		5.6		2.1		2.1	5.6
Postretirement benefits	2.2		6.8		2.2		2.2	6.8
Employee benefits	9.7		12.3		9.7		9.7	12.3
State net operating losses	8.6		9.4		8.6		8.6	9.4
Other	3.2		3.4		3.2		3.2	3.4
Total deferred tax assets	41.7		58.8		41.7		41.7	58.8
Valuation allowance	(7)		(10.4)		(7)		(7)	(10.4)
Total deferred tax assets net of valuation allowance	34.7		48.4		34.7		34.7	48.4
Deferred tax liabilities:
Tangible and intangible assets	(50.2)		(85.5)		(50.2)		(50.2)	(85.5)
Other	(0.2)		(0.1)		(0.2)		(0.2)	(0.1)
Total deferred tax liabilities	(50.4)		(85.6)		(50.4)		(50.4)	(85.6)
Net deferred tax liabilities	(15.7)		(37.2)		(15.7)		(15.7)	(37.2)
Reconciliation of unrecognized tax benefits
Balance, beginning of year						$ 4.4	4.4	12.9	2.2
Additions for tax positions of prior years								0.4	10.7
Effective settlement of prior tax position								(8.9)
Balance, end of year	4.4		4.4		4.4		$ 4.4	4.4	12.9
Unrecognized tax benefit resulting from statute lapse								2.2
Minimum
Deferred tax liabilities:
Period for net operating losses carry forward (in years)							5 years
Maximum
Deferred tax liabilities:
Period for net operating losses carry forward (in years)							20 years
Accrued Liabilities
Deferred tax liabilities:
Income tax payable			$ 12.3					12.3
Other Current Assets
Deferred tax liabilities:
Income tax receivable	$ 1				$ 1		$ 1
Domestic
Reasons for difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate
Income before provision for income taxes							58.7	57.7	55.7
Foreign
Reasons for difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate
Income before provision for income taxes							$ 18.5	$ 19.4	$ 13.2
Corrections
Reasons for difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate
Income tax expense in discontinued operations				1.5
Income tax benefit from continued operations				(1.3)
Immaterial errors
Reasons for difference between the provision for income taxes on pre-tax income from the amount computed by applying the U.S. federal statutory tax rate
Accrued Income Taxes				$ 0.2

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2018	May 31, 2017	May 31, 2016
Earnings Per Share
Effect to the participating securities as result of net loss									$ 0
Basic and Diluted EPS:
Income from continuing operations	$ 18.1	$ 31.3	$ 13.3	$ 11	$ 16.3	$ 14.4	$ 9.7	$ 11.6	73.7	$ 52	$ 45.5
Less income attributable to participating shares									(0.6)	(0.5)	(0.4)
Income from continuing operations attributable to common shareholders									73.1	51.5	45.1
Income (Loss) from discontinued operations attributable to common shareholders									(58.1)	4.5	2.2
Net income attributable to common shareholders for earnings per share									$ 15	$ 56	$ 47.3
Weighted Average Shares:
Weighted average common shares outstanding - basic									34,200,000	33,900,000	34,400,000
Additional shares from assumed exercise of stock options									400,000	400,000	200,000
Weighted average common shares outstanding - diluted									34,600,000	34,300,000	34,600,000
Earnings per share - basic:
Earnings from continuing operations	$ 0.53	$ 0.91	$ 0.39	$ 0.32	$ 0.48	$ 0.43	$ 0.28	$ 0.34	$ 2.14	$ 1.53	$ 1.30
Earnings (Loss) from discontinued operations	(0.18)	(0.46)	(1.05)	(0.01)	0.14	(0.02)	0.07	(0.06)	(1.70)	0.13	0.07
Earnings per share - basic	0.35	0.45	(0.66)	0.31	0.62	0.41	0.35	0.28	0.44	1.66	1.37
Earnings per share - diluted:
Earnings from continuing operations	0.52	0.90	0.38	0.32	0.48	0.42	0.28	0.34	2.11	1.51	1.30
Earnings (Loss) from discontinued operations	(0.18)	(0.46)	(1.05)	(0.01)	0.14	(0.02)	0.07	(0.06)	(1.70)	0.13	0.07
Earnings per share - diluted	$ 0.34	$ 0.44	$ (0.67)	$ 0.31	$ 0.62	$ 0.40	$ 0.35	$ 0.28	$ 0.41	$ 1.64	$ 1.37
Antidilutive shares excluded from the computation of diluted earnings per share (in shares)										11,200	1,374,200

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Cash balance pension plan
Employee benefit plans
Interest crediting rate as a percentage of average 30-year treasury rate	100.00%
Average period of treasury rate used in determination of interest crediting rate	30 years
Average interest crediting rate (as a percent)	4.46%
Defined Benefit Pension Plans
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$ 145.4	$ 145.7
Service cost	2.4	2.5
Interest cost	4.3	4.2
Participant contributions	0.4	0.3
Net actuarial gain	(2.3)	(2)
Benefits and administrative payments	(6.5)	(6)
Plan change	0.7
Foreign currency translation adjustment	2.1	0.7
Projected benefit obligation at end of year	146.5	145.4	$ 145.7
Change in the fair value of plan assets:
Fair value of plan assets at beginning of year	118.8	111
Actual return on plan assets	11.6	9.9
Employer contributions	8.4	2.9
Participant contributions	0.4	0.3
Benefits and administrative payments	(6.5)	(6)
Foreign currency translation adjustment	1.8	0.7
Fair value of plan assets at end of year	134.5	118.8	111
Funded status at end of year	(12)	(26.6)
Amounts recognized in the consolidated balance sheets
Non-current assets	0.5
Accrued liabilities	(1.2)	(2.7)
Other liabilities and deferred income	(11.3)	(23.9)
Funded status at end of year	(12)	(26.6)
Amounts recognized in accumulated other comprehensive loss
Actuarial loss	50.5	58.8
Prior service credit	(0.1)	(0.4)
Total	50.4	58.4
Accumulated benefit obligation	140.2	140
Accumulated benefit obligation in excess of plan assets
Fair value of plan assets	0.5
Net Periodic Benefit Cost
Service cost	2.4	2.5	2.5
Interest cost	4.3	4.2	4.5
Expected return on plan assets	(7.3)	(6.5)	(6.5)
Curtailment	0.3
Amortization of prior service cost			0.1
Recognized net actuarial loss	2.3	2.4	2.4
Total	2	$ 2.6	$ 3
Estimated amounts that will be amortized from accumulated other comprehensive loss into expense over the next fiscal year
Net actuarial loss	1.8
Total	$ 1.8
Domestic plans
Key weighted-average assumptions used in the measurement of the company's projected benefit obligations
Discount rate (as a percent)	4.05%	3.82%
Rate of compensation increase (as a percent)		2.50%
Weighted-average assumptions used to determine net periodic pension expense
Discount rate: (as a percent)	3.82%	3.83%	4.15%
Rate of compensation increase: (as a percent)	2.50%	2.50%	2.50%
Expected long-term rate on plan assets: (as a percent)	7.25%	7.25%	7.25%
Plan Assets
Actual asset allocation (as a percent)	100.00%	100.00%
Domestic plans | Equity securities
Plan Assets
Actual asset allocation (as a percent)	59.00%	62.00%
Domestic plans | Fixed income securities
Plan Assets
Actual asset allocation (as a percent)	22.00%	16.00%
Domestic plans | Other
Plan Assets
Actual asset allocation (as a percent)	19.00%	22.00%
Domestic plans | Minimum | Equity securities
Plan Assets
Target Asset Allocation (as a percent)	45.00%
Domestic plans | Minimum | Fixed income securities
Plan Assets
Target Asset Allocation (as a percent)	15.00%
Domestic plans | Minimum | Other
Plan Assets
Target Asset Allocation (as a percent)	0.00%
Domestic plans | Maximum | Equity securities
Plan Assets
Target Asset Allocation (as a percent)	75.00%
Domestic plans | Maximum | Fixed income securities
Plan Assets
Target Asset Allocation (as a percent)	45.00%
Domestic plans | Maximum | Other
Plan Assets
Target Asset Allocation (as a percent)	25.00%
International plans
Key weighted-average assumptions used in the measurement of the company's projected benefit obligations
Discount rate (as a percent)	1.90%	2.00%
Rate of compensation increase (as a percent)	3.00%	3.00%
Weighted-average assumptions used to determine net periodic pension expense
Discount rate: (as a percent)	2.00%	1.90%	1.90%
Rate of compensation increase: (as a percent)	3.00%	3.00%	3.00%
Expected long-term rate on plan assets: (as a percent)	4.00%	4.00%	4.00%

Employee Benefit Plans - Reconc

Employee Benefit Plans - Reconciliation of Pension Assets (Details) - Defined Benefit Pension Plans - USD ($) $ in Millions	May 31, 2018	May 31, 2017	May 31, 2016
Employee benefit plans
Fair value of plan assets	$ 134.5	$ 118.8	$ 111
Total
Employee benefit plans
Fair value of plan assets	134.5	118.8
U.S. mutual funds | Total
Employee benefit plans
Fair value of plan assets	32.8	30.6
International mutual funds | Total
Employee benefit plans
Fair value of plan assets	10.4	9.5
Government securities and corporate bond mutual funds | Total
Employee benefit plans
Fair value of plan assets	15.7	10.1
Funds-of-funds | Total
Employee benefit plans
Fair value of plan assets	61.3	58.9
Hedge funds | Total
Employee benefit plans
Fair value of plan assets	4.4	6.8
Insurance annuities | Total
Employee benefit plans
Fair value of plan assets	7.8
Cash and cash equivalents | Total
Employee benefit plans
Fair value of plan assets	2.1	2.9
Quoted prices in active markets (Level 1)
Employee benefit plans
Fair value of plan assets	61	53.1
Quoted prices in active markets (Level 1) | U.S. mutual funds
Employee benefit plans
Fair value of plan assets	32.8	30.6
Quoted prices in active markets (Level 1) | International mutual funds
Employee benefit plans
Fair value of plan assets	10.4	9.5
Quoted prices in active markets (Level 1) | Government securities and corporate bond mutual funds
Employee benefit plans
Fair value of plan assets	15.7	10.1
Quoted prices in active markets (Level 1) | Cash and cash equivalents
Employee benefit plans
Fair value of plan assets	2.1	2.9
Significant other observable inputs (Level 2)
Employee benefit plans
Fair value of plan assets	53.6	51.6
Significant other observable inputs (Level 2) | Funds-of-funds
Employee benefit plans
Fair value of plan assets	53.6	51.6
Significant other unobservable inputs (Level 3)
Employee benefit plans
Fair value of plan assets	19.9	14.1	14.1
Significant other unobservable inputs (Level 3) | Funds-of-funds
Employee benefit plans
Fair value of plan assets	7.7	7.3	7.5
Significant other unobservable inputs (Level 3) | Hedge funds
Employee benefit plans
Fair value of plan assets	4.4	$ 6.8	$ 6.6
Significant other unobservable inputs (Level 3) | Insurance annuities
Employee benefit plans
Fair value of plan assets	$ 7.8

Employee Benefit Plans - Reco59

Employee Benefit Plans - Reconciliation of Level 3 Pension Assets (Details) - Defined Benefit Pension Plans - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017
Change in the fair value of plan assets:
Fair value of plan assets at beginning of year	$ 118.8	$ 111
Fair value of plan assets at end of year	134.5	118.8
Significant other unobservable inputs (Level 3)
Change in the fair value of plan assets:
Fair value of plan assets at beginning of year	14.1	14.1
Purchases	7.8
Sales	(3)	(0.8)
Return on plan assets related to assets still held	1	0.8
Fair value of plan assets at end of year	19.9	14.1
Significant other unobservable inputs (Level 3) | Funds-of-funds
Change in the fair value of plan assets:
Fair value of plan assets at beginning of year	7.3	7.5
Sales		(0.8)
Return on plan assets related to assets still held	0.4	0.6
Fair value of plan assets at end of year	7.7	7.3
Significant other unobservable inputs (Level 3) | Hedge funds
Change in the fair value of plan assets:
Fair value of plan assets at beginning of year	6.8	6.6
Sales	(3)
Return on plan assets related to assets still held	0.6	0.2
Fair value of plan assets at end of year	4.4	$ 6.8
Significant other unobservable inputs (Level 3) | Insurance annuities
Change in the fair value of plan assets:
Purchases	7.8
Fair value of plan assets at end of year	$ 7.8

Employee Benefit Plans - Future

Employee Benefit Plans - Future Benefit Payments and Defined Contribution Plan (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Defined Contribution Plan
Vesting period	3 years
Expense charged to statement of income	$ 9.2	$ 11.6	$ 10.3
Maximum
Defined Contribution Plan
Maximum percentage of pretax compensation that can be contributed by employees' for 401 (k) defined contribution plan	75.00%
Maximum matching contribution of employer for 401 (k) defined contribution plan (as a percent)	5.00%
Defined Benefit Pension Plans
Estimated future pension payments
2,019	$ 8
2,020	6.2
2,021	6
2,022	6.5
2,023	6.9
2024 to 2028	34.2
Funded status
Unfunded projected benefit obligation	12	26.6
Domestic plans
Estimated future pension payments
Anticipated contribution in next fiscal year	2.9
Postretirement Benefits Other Than Pensions
Funded status
Unfunded projected benefit obligation	$ 0.4	$ 0.7

Accumulated Other Comprehensi61

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Accumulated Other Comprehensive Loss
Balance at beginning of the period	$ (39.9)	$ (44.4)	$ (40.4)
Other comprehensive income (loss) before reclassifications	6.2	2.9	(5.6)
Amounts reclassified from AOCL	1.7	1.6	1.6
Total other comprehensive income (loss), net of tax	7.9	4.5	(4)
Balance at end of the period	(32)	(39.9)	(44.4)
Currency Translation Adjustments
Accumulated Other Comprehensive Loss
Balance at beginning of the period	(1.7)	(1.1)	0.9
Reclassifications within AOCL			(2)
Other comprehensive income (loss) before reclassifications	2	(0.6)
Total other comprehensive income (loss), net of tax	2	(0.6)
Balance at end of the period	0.3	(1.7)	(1.1)
Pensions Plans
Accumulated Other Comprehensive Loss
Balance at beginning of the period	(38.2)	(43.3)	(41.3)
Reclassifications within AOCL			2
Other comprehensive income (loss) before reclassifications	4.2	3.5	(5.6)
Amounts reclassified from AOCL	1.7	1.6	1.6
Total other comprehensive income (loss), net of tax	5.9	5.1	(4)
Balance at end of the period	$ (32.3)	$ (38.2)	$ (43.3)

Commitments and Contingencies -

Commitments and Contingencies - Aircraft Sale-Leaseback (Details) - Garden City lease - USD ($) $ in Millions	Oct. 03, 2003	May 31, 2018	May 31, 2017
Aircraft Sale-Leaseback Transactions
Proceeds from sale-leaseback	$ 14
Cost of the facility	9.5
Accumulated depreciation of the facility	4.6
Deferred gain realized on the sale	$ 9.1
Deferred gain amortization period	20 years
Unamortized balance of the deferred gain		$ 2.5	$ 2.9

Commitments and Contingencies63

Commitments and Contingencies - Operating Lease, Rental Expense, Purchase Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Aggregate amount of purchase obligations due in each of the next five fiscal years
2,019	$ 203.4
2,020	43.8
2,021	6
2,022	0
2,023	0
Letters of credit and performance bonds outstanding	16.7
Facilities and Equipment
Future minimum payments under operating leases
2,019	17.5
2,020	16.3
2,021	13
2,022	10.8
2,023	10
2024 and thereafter	27.2
Rental expense
Rental expense, net	$ 23.5	$ 22.9	$ 21.3

Other Noncurrent Assets (Detail

Other Noncurrent Assets (Details) - USD ($) $ in Millions	May 31, 2018	May 31, 2017
Other Noncurrent Assets
Costs in excess of billings	$ 39	$ 19.1
Assets under deferred compensation plan	35.7	32.1
Cash surrender value of life insurance	16.8	17.8
License fees	10.6	14.4
Investments in joint ventures	7.6	15
Other	9.2	6.5
Other Assets, Noncurrent, Total	$ 118.9	$ 104.9

Other Noncurrent Assets - Licen

Other Noncurrent Assets - License Fees (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jun. 30, 2011USD ($)	May 31, 2018USD ($)aircraft	May 31, 2017USD ($)	May 31, 2016USD ($)
Intangible assets
License fees		$ 10.6	$ 14.4
Aircraft | Owned Through Joint Ventures
Investments in Joint Ventures
Number of aircraft sold by joint ventures | aircraft		2
Net cash proceeds from sale of aircraft by joint ventures		$ 7.3
Gain from sale of aircraft by joint venture partners		0.4
Payment of evaluation and inspection services		0.4	1.2	$ 0.9
Exclusive distribution rights | Unison Industries
Intangible assets
Term of agreement	10 years
Amount agreed to be paid	$ 20
Amount paid	$ 7
Amount payable in each calendar year			1.3
Licensing Agreements | Unison Industries
Intangible assets
License fees		$ 5.6	$ 7.2
Amortization period		10 years
Current portion of the deferred payments		$ 1.3
Long-term portion		$ 2.2

Acquisitions (Details)

Acquisitions (Details) $ in Millions	Oct. 18, 2017facility	Sep. 19, 2017USD ($)facility	Apr. 10, 2017USD ($)aircraft	Dec. 04, 2015USD ($)	May 31, 2018USD ($)	May 31, 2017USD ($)	May 31, 2016USD ($)
Fair value of net assets acquired
Goodwill					$ 118.7	$ 105.6	$ 107.5
MRO facilities acquired in Canada owned by Premier Aviation
Acquisitions
Number of facilities acquired | facility	2	2
Total consideration		$ 24.8
Deferred consideration payable		1.9
Purchase price		22.9
Fair value of net assets acquired
Current assets		4.1
Property and equipment		13.1
Intangible assets, including goodwill		16
Accounts payable and accrued liabilities		(8.4)
Net assets acquired		$ 24.8
ACLAS
Acquisitions
Deferred consideration payable			$ 3
Number of aircrafts under multi-year component support and repair contract | aircraft			100
Deferred consideration payable period			3 years
Purchase price			$ 12
Fair value of net assets acquired
Inventory			5
Equipment on or available for long-term lease			6.2
Intangible assets			3.8
Assets acquired, net			$ 15
Vantem Modular LLC
Acquisitions
Purchase price				$ 4.8
Fair value of net assets acquired
Current assets				1.5
Equipment				0.5
Intangible assets				3.5
Contingent consideration				(2)
Assets acquired, net				3.5
Goodwill				1.3
Vantem Modular LLC | Maximum
Acquisitions
Future royalties				$ 5

Business Segment Information -

Business Segment Information - Segment Data (Details) $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2018USD ($)	Feb. 28, 2018USD ($)	Nov. 30, 2017USD ($)	Aug. 31, 2017USD ($)	May 31, 2017USD ($)	Feb. 28, 2017USD ($)	Nov. 30, 2016USD ($)	Aug. 31, 2016USD ($)	May 31, 2018USD ($)segment	May 31, 2017USD ($)	May 31, 2016USD ($)
Business Segment Information
Number of business segments | segment									2
Net sales	$ 473.5	$ 456.3	$ 420.6	$ 397.9	$ 450.5	$ 407.2	$ 371.3	$ 361.8	$ 1,748.3	$ 1,590.8	$ 1,525.4
Gross profit	84.7	$ 77.6	$ 70.7	$ 61.6	77.9	$ 66.5	$ 59.5	$ 59.5	294.6	263.4	233.1
Total assets	1,524.7				1,504.1				1,524.7	1,504.1
Capital expenditures									27	33.6	89
Depreciation and amortization, including depreciation and amortization of stock-based compensation, Net									63.1	63.9	57.8
Continuing operations
Business Segment Information
Capital expenditures									22	25.2	40.1
Depreciation and amortization, including depreciation and amortization of stock-based compensation, Gross									55.8	46.7	39.7
Discontinued operations
Business Segment Information
Capital expenditures									5	8.4	48.9
Depreciation and amortization, including depreciation and amortization of stock-based compensation, Gross									7.3	17.2	18.1
Aviation Services
Business Segment Information
Net sales									1,618.9	1,485.4	1,425
Gross profit									271.9	246	229.5
Total assets	1,205.8				1,057				1,205.8	1,057
Aviation Services | Continuing operations
Business Segment Information
Capital expenditures									18.6	15	16.4
Depreciation and amortization, including depreciation and amortization of stock-based compensation, Gross									34.6	30.8	26.2
Expeditionary Services
Business Segment Information
Net sales									129.4	105.4	100.4
Gross profit									22.7	17.4	3.6
Total assets	130.2				122.8				130.2	122.8
Expeditionary Services | Continuing operations
Business Segment Information
Capital expenditures									2.1	2	1.6
Depreciation and amortization, including depreciation and amortization of stock-based compensation, Gross									4.6	5	6.8
Corporate | Continuing operations
Business Segment Information
Capital expenditures									1.3	8.2	22.1
Depreciation and amortization, including depreciation and amortization of stock-based compensation, Gross									16.6	10.9	$ 6.7
Corporate | Discontinued operations
Business Segment Information
Total assets	$ 188.7				$ 324.3				$ 188.7	$ 324.3

Business Segment Information 68

Business Segment Information - Recon of Segment Gross Profit to Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2018	May 31, 2017	May 31, 2016
Reconciliation of segment gross profit to income before provision for income taxes (benefit)
Segment gross profit	$ 84.7	$ 77.6	$ 70.7	$ 61.6	$ 77.9	$ 66.5	$ 59.5	$ 59.5	$ 294.6	$ 263.4	$ 233.1
Selling, general and administrative									(208.6)	(181.1)	(157.6)
Other expenses									(0.9)		(0.4)
Interest expense									(8)	(5.3)	(6.4)
Interest income									0.1	0.1	0.2
Income from continuing operations before provision for income taxes									$ 77.2	$ 77.1	$ 68.9

Business Segment Information 69

Business Segment Information - Sales by Product and Services (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2018	May 31, 2017	May 31, 2016
Net sales	$ 473.5	$ 456.3	$ 420.6	$ 397.9	$ 450.5	$ 407.2	$ 371.3	$ 361.8	$ 1,748.3	$ 1,590.8	$ 1,525.4
Aviation supply chain
Net sales									1,066	998.7	903.2
Maintenance, repair and overhaul services
Net sales									552.9	486.7	521.8
Mobility products
Net sales									112.5	$ 105.4	$ 100.4
Airlift
Net sales									$ 16.9

Business Segment Information 70

Business Segment Information - Geographic Data (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2018	May 31, 2017	May 31, 2016
Business Segment Information
Long-lived assets	$ 582				$ 615.7				$ 582	$ 615.7
Sales	473.5	$ 456.3	$ 420.6	$ 397.9	450.5	$ 407.2	$ 371.3	$ 361.8	1,748.3	1,590.8	$ 1,525.4
Continuing operations
Business Segment Information
Long-lived assets	582				517.9				582	517.9
Discontinued operations
Business Segment Information
Long-lived assets					97.8					97.8
Aviation Services
Business Segment Information
Sales									1,618.9	1,485.4	1,425
Expeditionary Services
Business Segment Information
Sales									129.4	105.4	100.4
United States
Business Segment Information
Long-lived assets	393.1				369.1				393.1	369.1
Europe
Business Segment Information
Long-lived assets	103.3				108.5				103.3	108.5
Other
Business Segment Information
Long-lived assets	$ 85.6				$ 40.3				85.6	40.3
Foreign countries
Business Segment Information
Sales									$ 694	$ 595.4	$ 498
Foreign countries | Total sales | Geographic concentration
Business Segment Information
Percentage of total sales									39.70%	37.40%	32.60%
U.S. Department of Defense, other U.S. government agencies and their contractors
Business Segment Information
Sales									$ 304.3	$ 321.5	$ 366.1
Percentage of total sales									17.40%	20.20%	24.00%
U.S. Department of Defense, other U.S. government agencies and their contractors | Aviation Services
Business Segment Information
Sales									$ 224.4	$ 260.2	$ 301.1
U.S. Department of Defense, other U.S. government agencies and their contractors | Expeditionary Services
Business Segment Information
Sales									$ 79.9	$ 61.3	$ 65

Legal Proceedings (Details)

Legal Proceedings (Details) - DynCorp International LLC v. AAR Airlift Group, Inc.	Feb. 01, 2018	Jan. 31, 2018
Legal Proceedings
Number of days expected to file a stipulation of dismissal with prejudice		14 days
Number of days to move court for the purpose of entering a stipulated form of a final order or judgement or open the case for further proceedings	60 days

Selected Quarterly Data (Unau72

Selected Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2018	May 31, 2017	May 31, 2016
Sales	$ 473.5	$ 456.3	$ 420.6	$ 397.9	$ 450.5	$ 407.2	$ 371.3	$ 361.8	$ 1,748.3	$ 1,590.8	$ 1,525.4
Gross profit	84.7	77.6	70.7	61.6	77.9	66.5	59.5	59.5	294.6	263.4	233.1
Income from continuing operations	18.1	31.3	13.3	11	16.3	14.4	9.7	11.6	73.7	52	45.5
Income (Loss) from discontinued operations, net of tax	(6.1)	(15.8)	(35.8)	(0.4)	4.9	(0.7)	2.4	(2.1)	(58.1)	4.5	2.2
Net income (loss)	$ 12	$ 15.5	$ (22.5)	$ 10.6	$ 21.2	$ 13.7	$ 12.1	$ 9.5	$ 15.6	$ 56.5	$ 47.7
Earnings (Loss) per share - basic:
Earnings (Loss) from continuing operations	$ 0.53	$ 0.91	$ 0.39	$ 0.32	$ 0.48	$ 0.43	$ 0.28	$ 0.34	$ 2.14	$ 1.53	$ 1.30
Earnings (Loss) from discontinued operations	(0.18)	(0.46)	(1.05)	(0.01)	0.14	(0.02)	0.07	(0.06)	(1.70)	0.13	0.07
Earnings per share - basic	0.35	0.45	(0.66)	0.31	0.62	0.41	0.35	0.28	0.44	1.66	1.37
Earnings (Loss) per share - diluted:
Earnings (Loss) from continuing operations	0.52	0.90	0.38	0.32	0.48	0.42	0.28	0.34	2.11	1.51	1.30
Earnings (Loss) from discontinued operations	(0.18)	(0.46)	(1.05)	(0.01)	0.14	(0.02)	0.07	(0.06)	(1.70)	0.13	0.07
Earnings per share - diluted	$ 0.34	$ 0.44	$ (0.67)	$ 0.31	$ 0.62	$ 0.40	$ 0.35	$ 0.28	$ 0.41	$ 1.64	$ 1.37
Discontinued Operations, Held-for-sale
Earnings (Loss) per share - diluted:
Impairment and other charges			$ 54.2
Goodwill impairment charge		$ 9.8

Allowance for Doubtful Accoun73

Allowance for Doubtful Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Changes in allowance for doubtful accounts
Balance, beginning of year	$ 4.9	$ 3.3	$ 4.8
Provision charged to operations	0.5	2.1	0.3
Recoveries, deductions for accounts written off and other reclassifications	2.1	(0.5)	(1.8)
Balance, end of year	$ 7.5	$ 4.9	$ 3.3