Supplemental Guarantor Information - Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Nov. 30, 2019	Aug. 31, 2019	Nov. 30, 2018	Aug. 31, 2018	Nov. 30, 2019	Nov. 30, 2018
Cash flows from operating activities:
Net income	$ 246,120	$ 250,812	$ 243,013	$ 212,515	$ 496,932	$ 455,528
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation					115,367	107,112
Amortization of intangible assets and capitalized contract costs					70,963	67,559
Stock-based compensation					69,398	74,784
Gain on sale of a cost method investment	0		(69,373)		0	(69,373)
Deferred income taxes					7,632	19,227
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net					(37,940)	(85,748)
Inventories, net					(13,402)	(53,227)
Uniforms and other rental items in service					(32,744)	(57,684)
Prepaid expenses and other current assets and capitalized contract costs					(68,409)	(58,161)
Accounts payable					28,055	(1,955)
Accrued compensation and related liabilities					(29,326)	(20,969)
Accrued liabilities and other					(17,883)	(15,322)
Income taxes, current					(17,292)	(17,204)
Net cash provided by operating activities					571,351	344,567
Cash flows from investing activities:
Capital expenditures					(126,167)	(137,614)
Purchases of investments					(10,121)	(14,071)
Proceeds from sale of assets					13,300	0
Proceeds from sale of a cost method investment			73,300		0	73,342
Acquisitions of businesses, net of cash acquired					(6,582)	(6,580)
Other, net					(2,103)	(1,717)
Net cash used in investing activities					(131,673)	(86,640)
Cash flows from financing activities:
(Payments) issuance of commercial paper, net					(112,500)	173,500
Proceeds from exercise of stock-based compensation awards					63,201	32,612
Repurchase of common stock					(258,741)	(508,129)
Other, net					(1,952)	(5,362)
Net cash used in financing activities					(309,992)	(307,379)
Effect of exchange rate changes on cash and cash equivalents					204	(793)
Net increase (decrease) in cash and cash equivalents					129,890	(50,245)
Cash and cash equivalents at beginning of period		96,645		138,724	96,645	138,724
Cash and cash equivalents at end of period	226,535		88,479		226,535	88,479
Eliminations
Cash flows from operating activities:
Net income	(251,347)		(240,465)		(510,012)	(451,120)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation					0	0
Amortization of intangible assets and capitalized contract costs					0	0
Stock-based compensation					0	0
Gain on sale of a cost method investment			0			0
Deferred income taxes					0	0
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net					0	(2,461)
Inventories, net					0	(1,631)
Uniforms and other rental items in service					3,277	0
Prepaid expenses and other current assets and capitalized contract costs					0	0
Accounts payable					(226)	(316)
Accrued compensation and related liabilities					0	0
Accrued liabilities and other					0	0
Income taxes, current					0	0
Net cash provided by operating activities					(506,961)	(455,528)
Cash flows from investing activities:
Capital expenditures					0	0
Purchases of investments					0	0
Proceeds from sale of assets					0
Proceeds from sale of a cost method investment						0
Acquisitions of businesses, net of cash acquired					0	0
Other, net					506,961	455,528
Net cash used in investing activities					506,961	455,528
Cash flows from financing activities:
(Payments) issuance of commercial paper, net					0	0
Proceeds from exercise of stock-based compensation awards					0	0
Repurchase of common stock					0	0
Other, net					0	0
Net cash used in financing activities					0	0
Effect of exchange rate changes on cash and cash equivalents					0	0
Net increase (decrease) in cash and cash equivalents					0	0
Cash and cash equivalents at beginning of period		0		0	0	0
Cash and cash equivalents at end of period	0		0		0	0
Cintas Corporation | Reportable Legal Entities
Cash flows from operating activities:
Net income	246,120		243,013		496,932	455,528
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation					0	0
Amortization of intangible assets and capitalized contract costs					0	0
Stock-based compensation					69,398	74,784
Gain on sale of a cost method investment			0			0
Deferred income taxes					0	0
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net					0	0
Inventories, net					0	0
Uniforms and other rental items in service					0	0
Prepaid expenses and other current assets and capitalized contract costs					0	0
Accounts payable					0	0
Accrued compensation and related liabilities					0	0
Accrued liabilities and other					0	0
Income taxes, current					0	0
Net cash provided by operating activities					566,330	530,312
Cash flows from investing activities:
Capital expenditures					0	0
Purchases of investments					0	0
Proceeds from sale of assets					0
Proceeds from sale of a cost method investment						0
Acquisitions of businesses, net of cash acquired					0	0
Other, net					(370,790)	(54,795)
Net cash used in investing activities					(370,790)	(54,795)
Cash flows from financing activities:
(Payments) issuance of commercial paper, net					0	0
Proceeds from exercise of stock-based compensation awards					63,201	32,612
Repurchase of common stock					(258,741)	(508,129)
Other, net					0	0
Net cash used in financing activities					(195,540)	(475,517)
Effect of exchange rate changes on cash and cash equivalents					0	0
Net increase (decrease) in cash and cash equivalents					0	0
Cash and cash equivalents at beginning of period		0		0	0	0
Cash and cash equivalents at end of period	0		0		0	0
Corp. 2 | Reportable Legal Entities
Cash flows from operating activities:
Net income	74,977		53,428		156,665	116,040
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation					75,691	68,929
Amortization of intangible assets and capitalized contract costs					64,325	61,044
Stock-based compensation					0	0
Gain on sale of a cost method investment			0			0
Deferred income taxes					6,490	10,865
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net					(24,190)	(52,953)
Inventories, net					(18,709)	(52,989)
Uniforms and other rental items in service					(31,448)	(39,481)
Prepaid expenses and other current assets and capitalized contract costs					(52,765)	(52,392)
Accounts payable					92,602	(98,465)
Accrued compensation and related liabilities					(39,911)	(16,186)
Accrued liabilities and other					3,820	(1,908)
Income taxes, current					(13,559)	(5,329)
Net cash provided by operating activities					219,011	(62,825)
Cash flows from investing activities:
Capital expenditures					(95,361)	(92,461)
Purchases of investments					(457)	(466)
Proceeds from sale of assets					0
Proceeds from sale of a cost method investment						0
Acquisitions of businesses, net of cash acquired					(6,582)	(6,580)
Other, net					(6,406)	(2,534)
Net cash used in investing activities					(108,806)	(102,041)
Cash flows from financing activities:
(Payments) issuance of commercial paper, net					(112,500)	173,500
Proceeds from exercise of stock-based compensation awards					0	0
Repurchase of common stock					0	0
Other, net					(1,952)	(5,362)
Net cash used in financing activities					(114,452)	168,138
Effect of exchange rate changes on cash and cash equivalents					0	0
Net increase (decrease) in cash and cash equivalents					(4,247)	3,272
Cash and cash equivalents at beginning of period		54,963		44,499	54,963	44,499
Cash and cash equivalents at end of period	50,716		47,771		50,716	47,771
Subsidiary Guarantors | Reportable Legal Entities
Cash flows from operating activities:
Net income	167,702		179,702		336,808	322,735
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation					32,499	31,274
Amortization of intangible assets and capitalized contract costs					2,559	2,339
Stock-based compensation					0	0
Gain on sale of a cost method investment			(69,373)			(69,373)
Deferred income taxes					1,309	5,519
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net					(11,743)	(20,151)
Inventories, net					6,042	3,546
Uniforms and other rental items in service					(2,268)	(11,051)
Prepaid expenses and other current assets and capitalized contract costs					(15,629)	(5,570)
Accounts payable					(65,280)	90,324
Accrued compensation and related liabilities					9,298	(6,468)
Accrued liabilities and other					(18,688)	(9,983)
Income taxes, current					(3,732)	(7,109)
Net cash provided by operating activities					271,175	326,032
Cash flows from investing activities:
Capital expenditures					(20,584)	(37,357)
Purchases of investments					(9,664)	(13,605)
Proceeds from sale of assets					0
Proceeds from sale of a cost method investment						73,342
Acquisitions of businesses, net of cash acquired					0	0
Other, net					(126,130)	(398,963)
Net cash used in investing activities					(156,378)	(376,583)
Cash flows from financing activities:
(Payments) issuance of commercial paper, net					0	0
Proceeds from exercise of stock-based compensation awards					0	0
Repurchase of common stock					0	0
Other, net					0	0
Net cash used in financing activities					0	0
Effect of exchange rate changes on cash and cash equivalents					0	0
Net increase (decrease) in cash and cash equivalents					114,797	(50,551)
Cash and cash equivalents at beginning of period		13,151		60,310	13,151	60,310
Cash and cash equivalents at end of period	127,948		9,759		127,948	9,759
Non- Guarantors | Reportable Legal Entities
Cash flows from operating activities:
Net income	8,668		7,335		16,539	12,345
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation					7,177	6,909
Amortization of intangible assets and capitalized contract costs					4,079	4,176
Stock-based compensation					0	0
Gain on sale of a cost method investment			0			0
Deferred income taxes					(167)	2,843
Change in current assets and liabilities, net of acquisitions of businesses:
Accounts receivable, net					(2,007)	(10,183)
Inventories, net					(735)	(2,153)
Uniforms and other rental items in service					(2,305)	(7,152)
Prepaid expenses and other current assets and capitalized contract costs					(15)	(199)
Accounts payable					959	6,502
Accrued compensation and related liabilities					1,287	1,685
Accrued liabilities and other					(3,015)	(3,431)
Income taxes, current					(1)	(4,766)
Net cash provided by operating activities					21,796	6,576
Cash flows from investing activities:
Capital expenditures					(10,222)	(7,796)
Purchases of investments					0	0
Proceeds from sale of assets					13,300
Proceeds from sale of a cost method investment						0
Acquisitions of businesses, net of cash acquired					0	0
Other, net					(5,738)	(953)
Net cash used in investing activities					(2,660)	(8,749)
Cash flows from financing activities:
(Payments) issuance of commercial paper, net					0	0
Proceeds from exercise of stock-based compensation awards					0	0
Repurchase of common stock					0	0
Other, net					0	0
Net cash used in financing activities					0	0
Effect of exchange rate changes on cash and cash equivalents					204	(793)
Net increase (decrease) in cash and cash equivalents					19,340	(2,966)
Cash and cash equivalents at beginning of period		$ 28,531		$ 33,915	28,531	33,915
Cash and cash equivalents at end of period	$ 47,871		$ 30,949		$ 47,871	$ 30,949