Authorized Regulatory Surcharge, Per CCF

No definition available.

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Namespace Prefix:	sjw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Memorandum accounts, Authorized Recovery

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Requested Service Charge Refund

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No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of public utility's approved rate increase (decrease) by regulatory agency.

+ References

No definition available.

+ Details

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- 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.

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No definition available.

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Balance Type:	na
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- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
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- Details

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Period Type:

- Details

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Balance Type:
Period Type:

Regulatory Rate Filings (Details) - USD ($)	Jun. 26, 2017	Jun. 01, 2017	Apr. 03, 2017	Jun. 06, 2017
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 7,550,000
Public Utilities, Requested Rate Increase (Decrease), Percentage			2.10%
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 12,407,000
Public Utilities, Approved Rate Increase (Decrease), Percentage	3.46%
Requested Service Charge Refund				$ 1,794,000
2014 WCMA [Member]
Public Utilities, General Disclosures [Line Items]
Memorandum Account, Authorized Recovery		$ 996,000
Authorized Regulatory Surcharge, Per CCF		0.08
2015 WCMA [Member]
Public Utilities, General Disclosures [Line Items]
Memorandum Account, Authorized Recovery		2,233,000
Authorized Regulatory Surcharge, Per CCF		$ 0.1441