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

The amount recognised as of the acquisition date for investment properties acquired in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for judicial deposit assets acquired in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for lease liabilities assumed in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for marketable securities assets acquired in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for other assets acquired in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for other financial assets acquired in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for other liabilities assumed in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for payables to related parties assumed in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for receivables from related parties acquired in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for right-of-use assets acquired in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for tax assets acquired in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for tax liabilities assumed in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for trade payables assumed in a business combination.

No definition available.

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

The amount recognised as of the acquisition date for trade receivables acquired in a business combination.

No definition available.

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

- References

No definition available.

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

The amount recognised as of the acquisition date for cash and cash equivalents acquired in a business combination. [Refer: Cash and cash equivalents; Business combinations [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 3
-IssueDate 2021-01-01
-Paragraph B64
-Subparagraph i
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2021-en-r&anchor=para_B64_i&doctype=Appendix&subtype=B
-URIDate 2021-03-24

Name:	ifrs-full_CashAndCashEquivalentsRecognisedAsOfAcquisitionDate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount of contingent liabilities recognised as of the acquisition date in a business combination. [Refer: Contingent liabilities [member]; Business combinations [member]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 3
-IssueDate 2021-01-01
-Paragraph B64
-Subparagraph i
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2021-en-r&anchor=para_B64_i&doctype=Appendix&subtype=B
-URIDate 2021-03-24

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 3
-IssueDate 2021-01-01
-Paragraph IE72
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2021-en-r&anchor=para_IE72&doctype=Illustrative%20Examples
-URIDate 2021-03-24

Name:	ifrs-full_ContingentLiabilitiesRecognisedAsOfAcquisitionDate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount recognised as of the acquisition date for deferred tax assets acquired in a business combination. [Refer: Deferred tax assets; Business combinations [member]]

Name:	ifrs-full_DeferredTaxAssetsRecognisedAsOfAcquisitionDate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount recognised as of the acquisition date for deferred tax liabilities assumed in a business combination. [Refer: Deferred tax liabilities; Business combinations [member]]

Name:	ifrs-full_DeferredTaxLiabilitiesRecognisedAsOfAcquisitionDate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount recognised as of the acquisition date for net identifiable assets acquired or liabilities assumed in a business combination. [Refer: Business combinations [member]]

Name:	ifrs-full_IdentifiableAssetsAcquiredLiabilitiesAssumed
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The amount recognised as of the acquisition date for plant, property and equipment acquired in a business combination. [Refer: Property, plant and equipment; Business combinations [member]]