Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended					6 Months Ended		9 Months Ended
	Feb. 28, 2015		Aug. 31, 2014 segment	Feb. 28, 2014		Feb. 28, 2015 segment		Feb. 28, 2015		Feb. 28, 2014		May 31, 2014
Segment Reporting Information
Number of operating segments			4			3
Revenue	$ 1,108,847			$ 1,110,973				$ 3,334,303		$ 3,335,150
Income (loss) before income taxes	157,459			133,229				498,448		392,196
Total assets	4,266,346			4,400,441		4,266,346		4,266,346		4,400,441		4,462,452
Cintas Document Shredding
Segment Reporting Information
Revenue				74,900						222,000
Income (loss) before income taxes				1,300						5,100
Total assets				484,100						484,100
Operating Segments | Rental Uniforms & Ancillary Products
Segment Reporting Information
Revenue	859,520			801,702				2,581,820		2,398,884
Income (loss) before income taxes	149,010			128,382				448,171		371,845
Total assets	2,941,476			2,852,065		2,941,476		2,941,476		2,852,065
Operating Segments | Uniform Direct Sales
Segment Reporting Information
Revenue	112,185			107,678				334,851		337,023
Income (loss) before income taxes	9,805			9,254				29,362		31,799
Total assets	127,652			138,994		127,652		127,652		138,994
Operating Segments | First Aid, Safety & Fire Protection
Segment Reporting Information
Revenue	137,142			126,743				417,632		377,203
Income (loss) before income taxes	14,802			10,654				41,155		32,685
Total assets	444,763			419,647		444,763		444,763		419,647
Corporate | Corporate
Segment Reporting Information
Revenue	0	[1]		74,850	[1]			0	[1]	222,040	[1]
Income (loss) before income taxes	(16,158)	[1]		(15,061)	[1]			(20,240)	[1]	(44,133)	[1]
Total assets	$ 752,455	[1]		$ 989,735	[1]	$ 752,455	[1]	$ 752,455	[1]	$ 989,735	[1]

[1] Corporate assets as of February 28, 2015 include the investment in the Shred-it partnership. Corporate assets also include the real estate assets of the Storage business that were not included in the sale transactions. Corporate results for the three months ended February 28, 2014 include the revenue ($74.9 million) and income before income taxes ($1.3 million) of the document shredding business. Corporate results and assets as of and for the nine months ended February 28, 2014 include the revenue ($222.0 million), income before income taxes ($5.1 million) and assets ($484.1 million) of the document shredding business.