Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015		Feb. 28, 2015		Nov. 30, 2014		Aug. 31, 2014		May 31, 2016	May 31, 2015	May 31, 2014
Quarterly Financial Data [Abstract]
Revenue	$ 1,271,405	$ 1,216,083	$ 1,219,080	$ 1,198,890	$ 1,142,583		$ 1,108,847		$ 1,123,379		$ 1,102,077		$ 4,905,458	$ 4,476,886	$ 4,193,844
Gross margin	553,718	524,608	527,400	524,144	486,660	[1]	475,307	[1]	481,424	[1]	477,946	[1],[2]	2,129,870	1,921,337	1,749,759
Net income, continuing operations	$ 118,011	$ 117,279	$ 115,453	$ 106,198	$ 100,584	[1]	$ 100,331	[1]	$ 103,701	[1]	$ 105,905	[1],[2]	$ 456,941	$ 410,521	$ 337,772
Basic earnings per share, continuing operations (dollars per share)	$ 1.09	$ 1.07	$ 1.05	$ 0.94	$ 0.87	[1]	$ 0.86	[1]	$ 0.88	[1]	$ 0.90	[1],[2]	$ 4.15	$ 3.51	$ 2.78
Diluted earnings per share from continuing operations (dollars per share)	$ 1.08	$ 1.05	$ 1.03	$ 0.93	$ 0.86	[1]	$ 0.85	[1]	$ 0.86	[1]	$ 0.89	[1],[2]	$ 4.09	$ 3.46	$ 2.75
Weighted average number of shares outstanding (shares)	106,136	107,843	108,301	110,597	113,666	[1]	116,178	[1]	117,115	[1]	116,659	[1],[2]	108,221	115,900	120,377
Gain on sale of stock of an equity method investment, net of tax											$ 13,600			$ 13,600

[1] The figures for fiscal 2015 reflect the change in classification of Shred-it to discontinued operations within the Consolidated Statements of Income. See Note 16 entitled Discontinued Operations for additional information.

[2] During the fiscal 2015 first quarter, Cintas recognized a gain on the sale of stock in an equity method investment in the net amount of $13.6 million.