Goodwill, Service Contracts and Other Assets (Information Regarding Service Contracts and Other Assets) (Details) (USD $)	12 Months Ended
	May 31, 2013		May 31, 2012		May 31, 2011
Information regarding service contracts and other assets
Service contracts, Net	$ 92,153,000		$ 76,822,000		$ 102,312,000
Other assets, Carrying Amount	202,099,000		186,062,000
Other assets, Accumulated Amortization	77,709,000		73,226,000
Other assets, Net	124,390,000		112,836,000
Cash surrender value of insurance policies	73,000,000		57,400,000
Equity method investments	27,600,000		31,900,000
Cost method investments	900,000		900,000
Gain on sale of equity investments	8,500,000
Noncompete and consulting agreements [Member]
Information regarding service contracts and other assets
Other assets, Carrying Amount	77,863,000		76,036,000
Other assets, Accumulated Amortization	72,970,000		69,954,000
Other assets, Net	4,893,000		6,082,000
Investments [Member]
Information regarding service contracts and other assets
Other assets, Carrying Amount	101,525,000	[1]	90,198,000	[1]
Other assets, Accumulated Amortization	0	[1]	0	[1]
Other assets, Net	101,525,000	[1]	90,198,000	[1]
Other [Member]
Information regarding service contracts and other assets
Other assets, Carrying Amount	22,711,000		19,828,000
Other assets, Accumulated Amortization	4,739,000		3,272,000
Other assets, Net	17,972,000		16,556,000
Service contracts [Member]
Information regarding service contracts and other assets
Service contracts, Carrying Amount	420,499,000		384,622,000
Service contracts, Accumulated Amortization	328,346,000		307,800,000
Service contracts, Net	$ 92,153,000		$ 76,822,000

[1] Investments at May 31, 2013, include the cash surrender value of insurance policies of $73.0 million, equity method investments of $27.6 million and cost method investments of $0.9 million. During fiscal 2013, Cintas sold stock of an equity method investment for a gain of $8.5 million. Investments at May 31, 2012, include the cash surrender value of insurance policies of $57.4 million, equity method investments of $31.9 million and cost method investments of $0.9 million.