Schedule II - Valuation and Qualifying Accounts and Reserves (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2013		May 31, 2012		May 31, 2011
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 17,017		$ 17,057		$ 14,297
Charged to Costs and Expense	2,804	[1]	5,165	[1]	7,835	[1]
Charged to Other Accounts	202	[2]	194	[2]	43	[2]
Deductions	4,168	[3]	5,399	[3]	5,118	[3]
Balance at End of Year	15,855		17,017		17,057
Reserve for Obsolete Inventory [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	29,376		30,717		32,466
Charged to Costs and Expense	4,041	[1]	4,247	[1]	1,626	[1]
Charged to Other Accounts	(2,223)	[2]	(1,505)	[2]	(8)	[2]
Deductions	1,707	[3]	4,083	[3]	3,367	[3]
Balance at End of Year	$ 29,487		$ 29,376		$ 30,717

[1] Represents amounts charged to expense to increase reserve for estimated future bad debts or to increase reserve for obsolete inventory. Amounts related to inventory are computed by performing a thorough analysis of future marketability by specific inventory item.

[2] Represents a change in the appropriate balance sheet reserve due to acquisitions during the respective period.

[3] Represents reductions in the balance sheet reserve due to the actual write-off of non-collectible accounts receivable or the physical disposal of obsolete inventory items. These amounts do not impact Cintas' consolidated income statement.