Goodwill, Service Contracts and Other Assets - Changes in Carrying Amount of Service Contracts (Details) $ in Thousands	9 Months Ended
Feb. 29, 2016 USD ($)
Service contracts [Roll Forward]
Beginning balance	$ 42,434
Service contracts acquired	55,203
Service contracts amortization	(11,222)
Foreign currency translation	(35)
Ending balance	86,380
Uniform Rental and Facility Services
Service contracts [Roll Forward]
Beginning balance	6,677
Service contracts acquired	18,473
Service contracts amortization	(3,623)
Foreign currency translation	0
Ending balance	21,527
First Aid and Safety Services
Service contracts [Roll Forward]
Beginning balance	1,576
Service contracts acquired	34,000
Service contracts amortization	(2,414)
Foreign currency translation	(35)
Ending balance	33,127
All Other
Service contracts [Roll Forward]
Beginning balance	34,181
Service contracts acquired	2,730
Service contracts amortization	(5,185)
Foreign currency translation	0
Ending balance	$ 31,726

Amount of reduction of finite-lived intangible assets due to amortization during the period.

No definition available.

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Namespace Prefix:	ctas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Amount of increase (decrease) to assets, excluding financial assets and goodwill, lacking physical substance with a finite life for foreign currency translation adjustments.

+ References

No definition available.

+ Details

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- Definition

Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, resulting from a business combination.

+ References

No definition available.

+ Details

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