Acquisitions and Deconsolidations - Narrative (Details) $ in Thousands		3 Months Ended			12 Months Ended
	Apr. 30, 2014 USD ($)	May. 31, 2015 USD ($)	Aug. 31, 2014 USD ($)	Feb. 28, 2014 USD ($)	May. 31, 2015 USD ($) transaction segment_business buyer	May. 31, 2014 USD ($) segment_business	May. 31, 2013 USD ($)
Business Acquisition [Line Items]
Gain on deconsolidation of Shredding		$ (1,000)	$ 4,100		$ 4,952	$ 106,441	$ 0
Shredding Transaction asset impairment charge					0	16,143	0
Transaction costs				$ 2,200	$ 0	28,481	$ 0
Professional and legal fees						4,700
Employee termination benefit costs						700
Stock compensation expense resulting from the immediate vesting related to the shredding transaction						12,400
Charge for information systems contracts						4,200
Incremental profit sharing and employee compensation						$ 6,500
Number of transactions involved in sale of business | transaction					3
Number of buyers involved in sale of business | buyer					3
Cintas Document Destruction Business
Business Acquisition [Line Items]
Carrying amount of business segment	$ 413,000
Shred-it Partnership
Business Acquisition [Line Items]
Contribution to partnership, consideration received, cash	180,000
Interest in the partnership, recorded at fair value	$ 339,400
Series of Business Acquisitions | Rental Uniforms & Ancillary Products
Business Acquisition [Line Items]
Number of businesses acquired | segment_business					1
Series of Business Acquisitions | First Aid, Safety & Fire Protection
Business Acquisition [Line Items]
Number of businesses acquired | segment_business					11	3
Series of Business Acquisitions | Corporate
Business Acquisition [Line Items]
Number of businesses acquired | segment_business						3