Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	May. 31, 2015		Feb. 28, 2015	[1],[2],[3]	Nov. 30, 2014	[1],[2],[3]	Aug. 31, 2014		May. 31, 2014	[1],[3],[4]	Feb. 28, 2014		Nov. 30, 2013	[1],[3],[4]	Aug. 31, 2013	[1],[3],[4]	May. 31, 2015	May. 31, 2014	May. 31, 2013
Quarterly Financial Data [Abstract]
Revenue	$ 1,142,583	[1],[2],[3]	$ 1,108,847		$ 1,123,379		$ 1,102,077	[1],[2],[3]	$ 1,134,415		$ 1,110,973	[1],[3],[4]	$ 1,123,931		$ 1,100,246		$ 4,476,886	$ 4,469,565	$ 4,245,964
Gross margin	486,660	[1],[2],[3]	475,307		481,424		477,946	[1],[2],[3]	480,847		469,634	[1],[3],[4]	467,079		456,095		1,921,337	1,873,654	1,753,309
Net income, continuing operations	$ 101,204	[1],[2],[3]	$ 93,636		$ 103,446		$ 109,791	[1],[2],[3]	$ 128,105		$ 84,326	[1],[3],[4]	$ 84,456		$ 77,398		$ 408,077	$ 374,285	$ 316,586
Basic earnings per share, continuing operations (dollars per share)	$ 0.88	[1],[2],[3]	$ 0.80		$ 0.87		$ 0.94	[1],[2],[3]	$ 1.05		$ 0.70	[1],[3],[4]	$ 0.70		$ 0.63		$ 3.49	$ 3.08	$ 2.54
Diluted earnings per share from continuing operations (in dollars per share)	$ 0.86	[1],[2],[3]	$ 0.79		$ 0.86		$ 0.93	[1],[2],[3]	$ 1.04		$ 0.69	[1],[3],[4]	$ 0.69		$ 0.63		$ 3.44	$ 3.05	$ 2.53
Weighted average number of shares outstanding (shares)	113,666	[1],[2],[3]	116,178		117,115		116,659	[1],[2],[3]	119,541		119,913	[1],[3],[4]	119,907		122,130		115,900	120,377	123,956
Gain (loss) on investment in Shred-it, net of tax																	$ (5,539)	$ 1,234	$ 0
Gain on sale of stock of an equity method investment, net of tax							$ 13,600										13,600
Gain on deconsolidation of Shredding	$ (1,000)						$ 4,100										4,952	106,441	0
Shredding Transaction asset impairment charge																	0	16,143	0
Shredding Transaction costs											$ 2,200						$ 0	$ 28,481	$ 0

[1] As a result of the Shredding Transaction, Cintas no longer includes Shredding results in its reported revenue, gross margin and operating income. After April 30, 2014, Cintas recognized its share of the Shred-it Partnership income, net of tax, in net income from continuing operations and diluted earnings per share ("EPS") from continuing operations. As a result of its investment in the Shred-it Partnership, Cintas recognized a net loss of $5.5 million and a net gain of $1.2 million during the years end May 31, 2015 and 2014, respectively.

[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. In the fiscal 2015 first quarter, Cintas also recorded an net gain of $4.1 million, related to the Shredding Transaction completed in fiscal 2014 as a result of receiving certain additional proceeds. Finally, in the fourth quarter of fiscal 2015, Cintas recorded a net loss of $1.0 million related to the Shredding Transaction completed in fiscal 2014 due to the settlement of an outstanding Shredding-related legal claim.

[3] The figures for both fiscal 2015 and 2014 reflect the change in classification of Storage to discontinued operations within the Consolidated Statements of Income. See Note 17 entitled Discontinued Operations for additional information.

[4] In accordance with GAAP, the fiscal 2014 Shredding revenue, gross margin, operating income, net income and EPS must continue to be included in the reported fiscal 2014 results because of Cintas' continuing ownership in the Shred-it Partnership. In addition, the fiscal 2014 results also included the following related to the Shredding Transaction: a $106.4 million gain on deconsolidation of Shredding, an asset impairment charge of $16.1 million and transaction costs of $28.5 million. All of these impacts were recorded in the fourth quarter except for $2.2 million of transaction costs that were recorded in the third quarter. Please see Note 9 entitled Acquisitions and Deconsolidations for additional information on the transaction.