v3.25.4

Earnings Per Share - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		18 Months Ended	38 Months Ended
	Jan. 07, 2026	Nov. 30, 2025	Nov. 30, 2024	Nov. 30, 2025	Nov. 30, 2024	Jan. 07, 2026	Sep. 30, 2025	Oct. 28, 2025	Jul. 23, 2024	Jul. 26, 2022
Equity, Class of Treasury Stock [Line Items]
Anti-dilutive stock options (in shares)		2,100	1,200	1,800	700
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Stock purchased under share buyback (in shares)	100
Stock purchased under share buyback, average price (in dollars per share)	$ 183.00
Total purchase price of shares repurchased	$ 3,700
July 26, 2022 Plan
Equity, Class of Treasury Stock [Line Items]
Share buyback program, authorized amount										$ 1,000,000
Stock purchased under share buyback (in shares)		569	0	1,272	2,732		5,400
Stock purchased under share buyback, average price (in dollars per share)		$ 199.39	$ 0	$ 207.13	$ 173.40		$ 185.01
Total purchase price of shares repurchased		$ 113,550	$ 0	$ 263,564	$ 473,617		$ 1,000,000
July 23, 2024 Plan
Equity, Class of Treasury Stock [Line Items]
Share buyback program, authorized amount									$ 1,000,000
Stock purchased under share buyback (in shares)		2,668	0	2,668	0
Stock purchased under share buyback, average price (in dollars per share)		$ 189.37	$ 0	$ 189.37	$ 0
Total purchase price of shares repurchased		$ 505,209	$ 0	$ 505,209	$ 0
July 23, 2024 Plan | Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Stock purchased under share buyback (in shares)						2,700
Stock purchased under share buyback, average price (in dollars per share)						$ 189.32
Total purchase price of shares repurchased						$ 508,900
October 28, 2025 Plan
Equity, Class of Treasury Stock [Line Items]
Share buyback program, authorized amount								$ 1,000,000
Stock purchased under share buyback (in shares)		0		0
Stock purchased under share buyback, average price (in dollars per share)		$ 0		$ 0
Total purchase price of shares repurchased		$ 0		$ 0
October 28, 2025 Plan | Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Stock purchased under share buyback (in shares)	0

X

- Definition

Amount authorized for purchase of share under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 505
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481520/505-30-50-4

+ Details

Name:	srt_StockRepurchaseProgramAuthorizedAmount1
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482662/260-10-50-1

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_EquityClassOfTreasuryStockLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Total cost of shares repurchased divided by the total number of shares repurchased.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481549/505-30-45-1

+ Details

Name:	us-gaap_TreasuryStockAcquiredAverageCostPerShare
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of shares that have been repurchased during the period and are being held in treasury.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

+ Details

Name:	us-gaap_TreasuryStockSharesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481549/505-30-45-1

+ Details

Name:	us-gaap_TreasuryStockValueAcquiredCostMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_ShareRepurchaseProgramAxis=ctas_ShareBuybackProgramJuly262022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_ShareRepurchaseProgramAxis=ctas_ShareBuybackProgramJuly232024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_ShareRepurchaseProgramAxis=ctas_ShareBuybackProgramOctober282025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: