Segment Reporting and Related Disclosures - Marginal Contribution by Segment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Segment Reporting Information [Line Items]
Marginal contribution	$ 9,722	$ 12,058	$ 34,478	$ 41,882
Unallocated SG&A expenses	8,010	8,394	25,123	24,532
Interest income/(expense), net	(221)	82	(385)	264
Other income	1	0	14	1,390
Income before income taxes	1,492	3,746	8,984	19,004
Operating Segments \| T&M
Segment Reporting Information [Line Items]
Marginal contribution	8,755	10,964	29,272	37,410
Operating Segments \| DP
Segment Reporting Information [Line Items]
Marginal contribution	$ 967	$ 1,094	$ 5,206	$ 4,472

Operating Income Excluding Fixed Selling, General and Administrative Expense

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- Definition

Selling, General and Administrative Expense, Fixed Costs

+ References

No definition available.

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- Definition

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

+ References

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

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- Definition

The net amount of operating interest income (expense).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.10)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 10
-Article 9

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- Definition

Reflects the sum of all other revenue and income recognized by the entity in the period not otherwise specified in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.4)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 4
-Article 7

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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