Segment Information - Information Related to Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended
Aug. 31, 2016	Aug. 31, 2015	May 31, 2016
Segment Reporting Information
Revenue	$ 1,294,130	$ 1,198,890
Income (loss) before income taxes	192,854	169,214
Total assets	4,167,145	4,116,465	$ 4,098,815
Operating Segments \| Uniform Rental and Facility Services
Segment Reporting Information
Revenue	999,596	938,408
Income (loss) before income taxes	185,245	165,381
Total assets	3,199,904	2,865,675
Operating Segments \| First Aid and Safety Services
Segment Reporting Information
Revenue	124,839	99,488
Income (loss) before income taxes	11,511	8,592
Total assets	436,920	397,573
Operating Segments \| All Other
Segment Reporting Information
Revenue	169,695	160,994
Income (loss) before income taxes	10,205	11,534
Total assets	366,554	341,839
Corporate
Segment Reporting Information
Revenue	0	0
Income (loss) before income taxes	(14,107)	(16,293)
Total assets	$ 163,767	$ 511,378

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

+ 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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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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