Segment Disclosure (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Feb. 28, 2015	Feb. 28, 2014	Feb. 28, 2015 Operating_Segment	Feb. 28, 2014	May 31, 2014
Segment Reporting [Abstract]
Number of operating segments			3us-gaap_NumberOfOperatingSegments
Financial information by segment
Revenues	$ 163,100us-gaap_SalesRevenueNet	$ 151,727us-gaap_SalesRevenueNet	$ 536,566us-gaap_SalesRevenueNet	$ 444,320us-gaap_SalesRevenueNet
Gross profit	38,734us-gaap_GrossProfit	39,300us-gaap_GrossProfit	139,767us-gaap_GrossProfit	126,554us-gaap_GrossProfit
Income (loss) from operations	3,870us-gaap_OperatingIncomeLoss	3,000us-gaap_OperatingIncomeLoss	25,726us-gaap_OperatingIncomeLoss	27,827us-gaap_OperatingIncomeLoss
Depreciation and amortization	8,114	7,300	24,779	20,850
Goodwill	166,531us-gaap_Goodwill		166,531us-gaap_Goodwill		130,516us-gaap_Goodwill
Total assets	477,329us-gaap_Assets		477,329us-gaap_Assets		443,972us-gaap_Assets
Operating segments \| Services
Financial information by segment
Revenues	121,845	109,122	404,651	313,794
Gross profit	27,429	26,216	101,452	83,881
Income (loss) from operations	7,257	7,452	36,208	32,698
Depreciation and amortization	5,658	4,591	16,622	12,982
Goodwill	116,567		116,567		73,767
Total assets	311,947		311,947		249,378
Operating segments \| International
Financial information by segment
Revenues	33,554	38,064	114,610	119,032
Gross profit	7,018	10,086	27,795	33,499
Income (loss) from operations	(1,315)	84	1,163	9,192
Depreciation and amortization	1,919	2,053	6,130	5,958
Goodwill	36,767		36,767		43,552
Total assets	125,427		125,427		155,571
Operating segments \| Products and Systems
Financial information by segment
Revenues	8,526	7,610	22,588	22,799
Gross profit	4,211	3,674	10,203	9,776
Income (loss) from operations	1,346	87	1,330	1,147
Depreciation and amortization	608	597	1,809	1,763
Goodwill	13,197		13,197		13,197
Total assets	35,410		35,410		38,041
Corporate and eliminations
Financial information by segment
Revenues	(825)	(3,069)	(5,283)	(11,305)
Gross profit	76	(676)	317	(602)
Income (loss) from operations	(3,418)	(4,623)	(12,975)	(15,210)
Depreciation and amortization	(71)	59	218	147
Total assets	$ 4,545		$ 4,545		$ 982

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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The net result for the period of deducting operating expenses from operating revenues.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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