The amount of shares authorised.

No definition available.

Name:	csan_AmountOfSharesAuthorised
Namespace Prefix:	csan_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The approval amount of increase in share capital.

+ References

No definition available.

+ Details

Name:	csan_ApprovalAmountOfIncreaseInShareCapital
Namespace Prefix:	csan_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represets the dividend payout ration of the entity.

+ References

No definition available.

+ Details

Name:	csan_DividendPayoutPercentage
Namespace Prefix:	csan_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The nominal value of fully paid in capital issued.

+ References

No definition available.

+ Details

Name:	csan_FullyPaidInIssuedCapital
Namespace Prefix:	csan_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Market value price per share.

+ References

No definition available.

+ Details

Name:	csan_MarketValuePricePerShare
Namespace Prefix:	csan_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of cancellation of treasury shares approved by Board of Directors.

+ References

No definition available.

+ Details

Name:	csan_NumberOfCancellationOfTreasurySharesApproved
Namespace Prefix:	csan_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares authorised by the entity for buyback.

+ References

No definition available.

+ Details

Name:	csan_NumberOfSharesBuybackAuthorised
Namespace Prefix:	csan_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of buyback shares represent total shares.

+ References

No definition available.

+ Details

Name:	csan_PercentageOfBuybackSharesRepresentTotalShares
Namespace Prefix:	csan_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of reserve allocation from net income for the year.

+ References

No definition available.

+ Details

Name:	csan_PercentageOfReserveAllocationFromNetIncome
Namespace Prefix:	csan_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of reserve allocation to net income for the year.

+ References

No definition available.

+ Details

Name:	csan_ThresholdPercentageLimitOfCapitalForLegalReserveToBeMaintained
Namespace Prefix:	csan_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Treasury shares shares.

+ References

No definition available.

+ Details

Name:	csan_TreasurySharesShares
Namespace Prefix:	csan_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of treasury stock cancelled during the period. [Refer: Treasury shares]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 106
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_106_d&doctype=Standard
-URIDate 2024-03-27

+ Details

Name:	ifrs-full_CancellationOfTreasuryShares
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfClassesOfShareCapitalLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of dividends recognised as distributions to owners of the parent. [Refer: Parent [member]]

+ References

+ Details

Name:	ifrs-full_DividendsRecognisedAsDistributionsToOwnersOfParent
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of shares issued by the entity.

+ References

+ Details

Name:	ifrs-full_NumberOfSharesIssued
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	ifrs-full_ClassesOfShareCapitalAxis=ifrs-full_OrdinarySharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ComponentsOfEquityAxis=csan_LegalReservesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

SHAREHOLDERS EQUITY - Additional Information (Detail) - BRL (R$) R$ / shares in Units, R$ in Thousands				12 Months Ended
	Aug. 13, 2024	May 29, 2024	Aug. 14, 2023	Dec. 31, 2024	Dec. 31, 2023
Disclosure of classes of share capital [line items]
Fully paid in issued capital				R$ 8,832,544	R$ 8,682,544
Amount of shares authorized				R$ 9,000,000
Approval amount of increase in share capital		R$ 150,000
Dividends paid		R$ 840,000
Dividend as a percetage of net income				25.00%
Cancellation of treasury shares	R$ 118,975
Number of cancellation of treasury shares authorized	7,500,000
Common shares [member]
Disclosure of classes of share capital [line items]
Number of nominative common shares				1,866,570,932
Number of shares buyback authorised			116,000,000
Percentage of buyback shares represent total shares			9.93%
Treasury shares				3,747,965	6,514,511
Market value per share				R$ 8.16
Legal reserve
Disclosure of classes of share capital [line items]
Percentage of reserve allocation from net income				5.00%
Threshold percentage limit of capital for legal reserve to be maintained				20.00%