Name:	SBS_AdvanceForFutureCapitalIncrease
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- References

No definition available.

Name:	SBS_DisclosureOfInvestmentsLineItems
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Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.

No definition available.

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Data Type:	xbrli:sharesItemType
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The amount of dividends recognised as distributions to owners.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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-IssueDate 2017-01-01
-Paragraph 107
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_107&doctype=Standard
-URIDate 2017-03-09

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The increase (decrease) in equity resulting from changes that the entity does not separately disclose in the same statement or note. [Refer: Equity]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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-URIDate 2017-03-09

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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The nominal value of capital issued.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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-Paragraph 78
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-URIDate 2017-03-09

Name:	ifrs-full_IssuedCapital
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The number of shares issued by the entity.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 106
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d&doctype=Standard
-URIDate 2017-03-09

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

The amount receivable by the entity that it does not separately disclose in the same statement or note.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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-Number 1
-IssueDate 2017-01-01
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-URIDate 2017-03-09

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The proportion of ownership interest in a joint venture attributable to the entity. [Refer: Joint ventures [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-URIDate 2017-03-09

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-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=27&date=2017-03-01&anchor=para_16_b_iii&doctype=Standard
-URIDate 2017-03-09

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-Subparagraph a
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-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=12&date=2017-03-01&anchor=para_21_a_iv&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_ProportionOfOwnershipInterestInJointVenture
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Name:	invest_InvestmentIssuerAxis=SBS_SesammMember
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Balance Type:
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Data Type:	na
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Name:	invest_InvestmentIssuerAxis=SBS_AguasDeCastilhoMember
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Data Type:	na
Balance Type:
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Name:	invest_InvestmentIssuerAxis=SBS_SaneaquaMairinqueMember
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Data Type:	na
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Name:	invest_InvestmentIssuerAxis=SBS_AttendAmbientalMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	invest_InvestmentIssuerAxis=SBS_AquapoloAmbientalMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	invest_InvestmentIssuerAxis=SBS_PaulistaGeradoraDeEnergiaMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=SBS_AnnualAndExtraordinaryShareholdersMeetingMember
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Data Type:	na
Balance Type:
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Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=SBS_AnnualAndExtraordinaryShareholdersMeeting1Member
Namespace Prefix:
Data Type:	na
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