Name:	csan_DisclosureOfRecentDevelopmentsAndOtherInformationLineItems
Namespace Prefix:	csan_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The amount of installments falling due of grants concession payable.

No definition available.

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

Represents the amount of investments in railway network.

No definition available.

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

The maximum handling capacity of goods for fertilizer per year at port terminal.

No definition available.

Name:	csan_MaximumHandlingCapacityOfFertilizerPerYearAtPortTerminal
Namespace Prefix:	csan_
Data Type:	dtr-types:massItemType
Balance Type:	na
Period Type:	duration

The maximum handling capacity of goods for grains and fertilizer per year at port terminal.

No definition available.

Name:	csan_MaximumHandlingCapacityOfGrainsAndFertilizerPerYearAtPortTerminal
Namespace Prefix:	csan_
Data Type:	dtr-types:massItemType
Balance Type:	na
Period Type:	duration

The maximum handling capacity of goods for grains per year at port terminal.

No definition available.

Name:	csan_MaximumHandlingCapacityOfGrainsPerYearAtPortTerminal
Namespace Prefix:	csan_
Data Type:	dtr-types:massItemType
Balance Type:	na
Period Type:	duration

The number of quarterly installments falling due pursuant to the terms of the concession agreement.

No definition available.

Name:	csan_NumberOfInstallmentsForConcessionAgreement
Namespace Prefix:	csan_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of outstanding balance of the acquisition financing.

No definition available.

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

Represents the percentage of reduction in income tax and additional amounts under tax benefit.

No definition available.

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

Represents the period of tax benefit.

No definition available.

Name:	csan_PeriodOfTaxBenefit
Namespace Prefix:	csan_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the shareholding percentage.

No definition available.

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

The amount of property that is being constructed or developed for future use as investment property. [Refer: Investment property]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2024-03-27

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

The cash inflow from sales of equity or debt instruments of other entities (other than receipts for those instruments considered to be cash equivalents and those held for dealing or trading purposes), classified as investing activities.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2024-01-01
-Paragraph 16
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2024-en-r&anchor=para_16_d&doctype=Standard
-URIDate 2024-03-27

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

Name:	ifrs-full_SegmentsAxis=csan_RumoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=csan_RumoSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_SignificantInvestmentsInAssociatesAxis=csan_ElevacoesPortuariasSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=csan_EmpresaBrasileiraDeTerminaisPortuariosSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=csan_ChsAgronegocioIndustriaEComercioLtdaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=csan_CLISULSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_CounterpartyNameAxis=csan_CorredorLogisticaEInfraestruturaSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=csan_RumoMalhaNorteSAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: