Balancing and Memorandum Account, Net

No definition available.

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Balancing and Memorandum Accounts, Revenue and Regulatory Assets

No definition available.

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Customer Refund for Over Rate Collections

No definition available.

Name:	sjw_CustomerRefundforOverRateCollections
Namespace Prefix:	sjw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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Regulated Operating Revenue, Water Surcharge

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Regulatory Rate Filings, Immediate Increase Requested, Percentage

No definition available.

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Regulatory Rate Filings, Increase, Percent of Authorized Revenue Approved

No definition available.

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Regulatory Rate Filings, Total Increase Requested, Percentage

No definition available.

Name:	sjw_RegulatoryRateFilingsIncreaseRequestedPercentOfAuthorizedRevenue
Namespace Prefix:	sjw_
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The amount of unregulated operating revenues recognized during the period.

No definition available.

Name:	us-gaap_UnregulatedOperatingRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Summary of Significant Accounting Policies (Revenue, Balancing and Memorandum Accounts) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			34 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Aug. 21, 2013	Oct. 27, 2010
Revenue from External Customer [Line Items]
Regulated operating revenue, water surcharge	$ 3,741	$ 3,862	$ 3,272
Balancing and memorandum accounts, including interest	8,167
Balancing and memorandum accounts, revenue and regulatory assets	5,019	2,604
Immediate increase requested, percentage					38.00%
Total increase requested, percentage					71.00%
Regulatory Rate Filings, Increase, Percent of Authorized Revenue Approved				33.00%
Customer Refund for Over Rate Collections				982
San Jose Water Company [Member]
Revenue from External Customer [Line Items]
Nonregulated operating revenue	$ 5,882	$ 5,523	$ 4,935