Supplemental Guarantor Information - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	May. 31, 2015	Aug. 31, 2014	May. 31, 2015	May. 31, 2014	May. 31, 2013
Cash flows from operating activities:
Net income			$ 430,618	$ 374,442	$ 315,442
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation			140,624	168,220	165,664
Amortization of intangible assets			14,458	22,642	23,713
Stock-based compensation			47,002	29,875	23,310
Gain on sale of Storage			(38,573)	0	0
(Gain) loss on deconsolidation of Shredding	$ 1,000	$ (4,100)	(4,952)	(106,441)	0
Gain on sale of stock of an equity method investment			(21,739)	0	0
Loss (gain) on investment in Shred-it Partnership			8,803	(2,000)	0
Shredding Transaction asset impairment charge			0	16,143	0
Shredding Transaction costs			0	26,057	0
Deferred income taxes			20,866	47,109	48,023
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net			(1,443)	(56,231)	(42,704)
Inventories, net			23,785	(11,062)	10,997
Uniforms and other rental items in service			(31,994)	(11,435)	(44,179)
Prepaid expenses and other current assets			(3,202)	(2,177)	(3,281)
Accounts payable			(33,445)	30,446	25,023
Accrued compensation and related liabilities			3,234	10,931	(13,161)
Accrued liabilities and other			33,066	54,237	31,873
Income taxes, current			(6,832)	15,213	12,028
Net cash provided by (used in) operating activities			580,276	605,969	552,748
Cash flows from investing activities:
Capital expenditures			(217,720)	(145,580)	(196,486)
Proceeds from redemption of marketable securities			161,938	54,196	161,478
Purchase of marketable securities and investments			(195,471)	(63,858)	(178,464)
Proceeds from Storage Transactions, net of cash contributed			158,428	0	0
Proceeds from Shredding Transaction, net of cash contributed			3,344	179,359	0
Proceeds from sale of stock of an equity method investment			29,933	0	0
Dividends received on equity method investment			5,247	0	0
Acquisitions of businesses, net of cash acquired			(15,495)	(33,441)	(69,370)
Other			1,383	(5,219)	(1,339)
Net cash provided by (used in) investing activities			44,987	(14,543)	(284,181)
Cash flows from financing activities:
Proceeds from issuance of debt			0	0	250,000
Repayment of debt			(518)	(8,187)	(225,636)
Proceeds from exercise of stock-based compensation awards			40,230	41,902	14,807
Dividends paid			(201,891)	(93,320)	(79,744)
Repurchase of common stock			(551,970)	(370,599)	(215,681)
Other			1,589	469	196
Net cash used in financing activities			(712,560)	(429,735)	(256,058)
Effect of exchange rate changes on cash and cash equivalents			(8,918)	(676)	(61)
Net (decrease) increase in cash and cash equivalents			(96,215)	161,015	12,448
Cash and cash equivalents at beginning of year		513,288	513,288	352,273	339,825
Cash and cash equivalents at end of year	417,073		417,073	513,288	352,273
Cintas Corporation
Cash flows from operating activities:
Net income			430,618	374,442	315,442
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation			0	0	0
Amortization of intangible assets			0	0	0
Stock-based compensation			47,002	29,875	23,310
Gain on sale of Storage			0
(Gain) loss on deconsolidation of Shredding			0	0
Gain on sale of stock of an equity method investment			0
Loss (gain) on investment in Shred-it Partnership			0	0
Shredding Transaction asset impairment charge				0
Shredding Transaction costs				0
Deferred income taxes			0	0	0
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net			0	0	0
Inventories, net			0	0	0
Uniforms and other rental items in service			0	0	0
Prepaid expenses and other current assets			0	0	0
Accounts payable			0	0	0
Accrued compensation and related liabilities			0	0	0
Accrued liabilities and other			0	0	0
Income taxes, current			0	0	0
Net cash provided by (used in) operating activities			477,620	404,317	338,752
Cash flows from investing activities:
Capital expenditures			0	0	0
Proceeds from redemption of marketable securities			0	0	0
Purchase of marketable securities and investments			0	0	0
Proceeds from Storage Transactions, net of cash contributed			0
Proceeds from Shredding Transaction, net of cash contributed			0	0
Proceeds from sale of stock of an equity method investment			0
Dividends received on equity method investment			0
Acquisitions of businesses, net of cash acquired			0	0	0
Other			235,951	13,783	(60,918)
Net cash provided by (used in) investing activities			235,951	13,783	(60,918)
Cash flows from financing activities:
Proceeds from issuance of debt			0	0	0
Repayment of debt			0	0	0
Proceeds from exercise of stock-based compensation awards			40,230	41,902	14,807
Dividends paid			(201,831)	(93,293)	(79,723)
Repurchase of common stock			(551,970)	(370,599)	(215,681)
Other			0	3,890	2,763
Net cash used in financing activities			(713,571)	(418,100)	(277,834)
Effect of exchange rate changes on cash and cash equivalents			0	0	0
Net (decrease) increase in cash and cash equivalents			0	0	0
Cash and cash equivalents at beginning of year		0	0	0	0
Cash and cash equivalents at end of year	0		0	0	0
Corp. 2
Cash flows from operating activities:
Net income			134,861	162,263	98,748
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation			87,186	110,100	16,647
Amortization of intangible assets			13,972	20,547	21,077
Stock-based compensation			0	0	0
Gain on sale of Storage			(31,113)
(Gain) loss on deconsolidation of Shredding			(4,952)	(111,661)
Gain on sale of stock of an equity method investment			0
Loss (gain) on investment in Shred-it Partnership			8,142	(1,850)
Shredding Transaction asset impairment charge				0
Shredding Transaction costs				0
Deferred income taxes			67	(2)	0
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net			4,370	(53,053)	(25,206)
Inventories, net			22,405	(14,735)	9,034
Uniforms and other rental items in service			(24,351)	(11,004)	(26,364)
Prepaid expenses and other current assets			(345)	(386)	507
Accounts payable			(322,461)	25,573	(55,802)
Accrued compensation and related liabilities			3,171	5,778	(9,206)
Accrued liabilities and other			(15,829)	50,008	(5,416)
Income taxes, current			358	2,621	1,110
Net cash provided by (used in) operating activities			(124,519)	184,199	25,129
Cash flows from investing activities:
Capital expenditures			(110,658)	(123,978)	(39,975)
Proceeds from redemption of marketable securities			0	0	0
Purchase of marketable securities and investments			(1,827)	(151,063)	(683)
Proceeds from Storage Transactions, net of cash contributed			93,387
Proceeds from Shredding Transaction, net of cash contributed			3,344	180,000
Proceeds from sale of stock of an equity method investment			0
Dividends received on equity method investment			0
Acquisitions of businesses, net of cash acquired			(15,495)	(13,199)	(67,431)
Other			42,199	(50,446)	58,589
Net cash provided by (used in) investing activities			124,350	(158,686)	(49,500)
Cash flows from financing activities:
Proceeds from issuance of debt			0	0	250,000
Repayment of debt			(1,178)	(8,436)	(225,866)
Proceeds from exercise of stock-based compensation awards			0	0	0
Dividends paid			0	0	0
Repurchase of common stock			0	0	0
Other			1,952	1,952	(3,989)
Net cash used in financing activities			774	(6,484)	20,145
Effect of exchange rate changes on cash and cash equivalents			0	0	0
Net (decrease) increase in cash and cash equivalents			605	19,029	(4,226)
Cash and cash equivalents at beginning of year		73,540	73,540	54,511	58,737
Cash and cash equivalents at end of year	74,145		74,145	73,540	54,511
Subsidiary Guarantors
Cash flows from operating activities:
Net income			281,160	205,009	216,727
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation			43,013	44,856	135,345
Amortization of intangible assets			60	153	200
Stock-based compensation			0	0	0
Gain on sale of Storage			0
(Gain) loss on deconsolidation of Shredding			0	0
Gain on sale of stock of an equity method investment			(21,739)
Loss (gain) on investment in Shred-it Partnership			0	0
Shredding Transaction asset impairment charge				16,143
Shredding Transaction costs				26,057
Deferred income taxes			18,565	47,373	53,916
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net			(7,095)	(1,300)	(15,326)
Inventories, net			(405)	4,839	(5,292)
Uniforms and other rental items in service			(5,006)	557	(11,590)
Prepaid expenses and other current assets			(2,740)	(1,844)	(3,620)
Accounts payable			289,110	23,246	75,034
Accrued compensation and related liabilities			1,400	4,947	(3,977)
Accrued liabilities and other			42,551	4,897	38,099
Income taxes, current			(6,155)	9,902	206
Net cash provided by (used in) operating activities			632,719	384,835	479,722
Cash flows from investing activities:
Capital expenditures			(92,600)	(9,591)	(131,208)
Proceeds from redemption of marketable securities			0	5,659	13,899
Purchase of marketable securities and investments			38,731	(242,956)	(31,075)
Proceeds from Storage Transactions, net of cash contributed			0
Proceeds from Shredding Transaction, net of cash contributed			0	0
Proceeds from sale of stock of an equity method investment			29,933
Dividends received on equity method investment			5,247
Acquisitions of businesses, net of cash acquired			0	0	112
Other			(764,336)	8,108	(315,519)
Net cash provided by (used in) investing activities			(783,025)	(238,780)	(463,791)
Cash flows from financing activities:
Proceeds from issuance of debt			(2,615)	(2,445)	638
Repayment of debt			2,962	(106)	445
Proceeds from exercise of stock-based compensation awards			0	0	0
Dividends paid			0	0	0
Repurchase of common stock			0	0	0
Other			(363)	8,951	769
Net cash used in financing activities			(16)	6,400	1,852
Effect of exchange rate changes on cash and cash equivalents			0	0	0
Net (decrease) increase in cash and cash equivalents			(150,322)	152,455	17,783
Cash and cash equivalents at beginning of year		399,525	399,525	247,070	229,287
Cash and cash equivalents at end of year	249,203		249,203	399,525	247,070
Non- Guarantors
Cash flows from operating activities:
Net income			17,001	20,809	32,793
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation			10,425	13,264	13,672
Amortization of intangible assets			426	1,942	2,436
Stock-based compensation			0	0	0
Gain on sale of Storage			(7,460)
(Gain) loss on deconsolidation of Shredding			0	5,220
Gain on sale of stock of an equity method investment			0
Loss (gain) on investment in Shred-it Partnership			661	(150)
Shredding Transaction asset impairment charge				0
Shredding Transaction costs				0
Deferred income taxes			2,234	(262)	(5,893)
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net			1,282	(1,878)	(2,172)
Inventories, net			(487)	450	626
Uniforms and other rental items in service			(2,764)	(973)	(4,077)
Prepaid expenses and other current assets			(117)	53	(168)
Accounts payable			(98)	(18,374)	5,794
Accrued compensation and related liabilities			(1,337)	206	22
Accrued liabilities and other			6,322	(689)	(829)
Income taxes, current			(1,035)	2,690	10,712
Net cash provided by (used in) operating activities			25,053	22,308	52,916
Cash flows from investing activities:
Capital expenditures			(14,462)	(12,011)	(25,303)
Proceeds from redemption of marketable securities			161,938	48,537	147,579
Purchase of marketable securities and investments			(179,130)	(48,387)	(158,378)
Proceeds from Storage Transactions, net of cash contributed			65,041
Proceeds from Shredding Transaction, net of cash contributed			0	(641)
Proceeds from sale of stock of an equity method investment			0
Dividends received on equity method investment			0
Acquisitions of businesses, net of cash acquired			0	(20,242)	(2,051)
Other			3,705	12,173	(15,609)
Net cash provided by (used in) investing activities			37,092	(20,571)	(53,762)
Cash flows from financing activities:
Proceeds from issuance of debt			2,615	2,445	(638)
Repayment of debt			(2,280)	376	(196)
Proceeds from exercise of stock-based compensation awards			0	0	0
Dividends paid			(60)	(27)	(21)
Repurchase of common stock			0	0	0
Other			0	(14,324)	653
Net cash used in financing activities			275	(11,530)	(202)
Effect of exchange rate changes on cash and cash equivalents			(8,918)	(676)	(61)
Net (decrease) increase in cash and cash equivalents			53,502	(10,469)	(1,109)
Cash and cash equivalents at beginning of year		40,223	40,223	50,692	51,801
Cash and cash equivalents at end of year	93,725		93,725	40,223	50,692
Eliminations
Cash flows from operating activities:
Net income			(433,022)	(388,081)	(348,268)
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation			0	0	0
Amortization of intangible assets			0	0	0
Stock-based compensation			0	0	0
Gain on sale of Storage			0
(Gain) loss on deconsolidation of Shredding			0	0
Gain on sale of stock of an equity method investment			0
Loss (gain) on investment in Shred-it Partnership			0	0
Shredding Transaction asset impairment charge				0
Shredding Transaction costs				0
Deferred income taxes			0	0	0
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net			0	0	0
Inventories, net			2,272	(1,616)	6,629
Uniforms and other rental items in service			127	(15)	(2,148)
Prepaid expenses and other current assets			0	0	0
Accounts payable			4	1	(3)
Accrued compensation and related liabilities			0	0	0
Accrued liabilities and other			22	21	19
Income taxes, current			0	0	0
Net cash provided by (used in) operating activities			(430,597)	(389,690)	(343,771)
Cash flows from investing activities:
Capital expenditures			0	0	0
Proceeds from redemption of marketable securities			0	0	0
Purchase of marketable securities and investments			(53,245)	378,548	11,672
Proceeds from Storage Transactions, net of cash contributed			0
Proceeds from Shredding Transaction, net of cash contributed			0	0
Proceeds from sale of stock of an equity method investment			0
Dividends received on equity method investment			0
Acquisitions of businesses, net of cash acquired			0	0	0
Other			483,864	11,163	332,118
Net cash provided by (used in) investing activities			430,619	389,711	343,790
Cash flows from financing activities:
Proceeds from issuance of debt			0	0	0
Repayment of debt			(22)	(21)	(19)
Proceeds from exercise of stock-based compensation awards			0	0	0
Dividends paid			0	0	0
Repurchase of common stock			0	0	0
Other			0	0	0
Net cash used in financing activities			(22)	(21)	(19)
Effect of exchange rate changes on cash and cash equivalents			0	0	0
Net (decrease) increase in cash and cash equivalents			0	0	0
Cash and cash equivalents at beginning of year		$ 0	0	0	0
Cash and cash equivalents at end of year	$ 0		0	0	0
Shred-it Partnership
Cash flows from investing activities:
Dividends received on equity method investment			113,400	$ 0	$ 0
Shred-it Partnership | Cintas Corporation
Cash flows from investing activities:
Dividends received on equity method investment			0
Shred-it Partnership | Corp. 2
Cash flows from investing activities:
Dividends received on equity method investment			113,400
Shred-it Partnership | Subsidiary Guarantors
Cash flows from investing activities:
Dividends received on equity method investment			0
Shred-it Partnership | Non- Guarantors
Cash flows from investing activities:
Dividends received on equity method investment			0
Shred-it Partnership | Eliminations
Cash flows from investing activities:
Dividends received on equity method investment			$ 0