XML 54 R27.htm IDEA: XBRL DOCUMENT
v2.4.0.8

General - Additional Information (Details) (USD $) In Thousands, unless otherwise specified | 0 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 29, 2014 | Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract] |  |
Water reduction target goal (percent) |  | 20.00%
Authorized Regulatory Surcharge, Gross | $ 46,700 |
Customer refund for over rate collections, one time refund | $ 200 |

X
- Definition Authorized Regulatory Surcharge, Gross + References No definition available. + Details
Name: | sjw_AuthorizedRegulatorySurchargeGross
Namespace Prefix: | sjw_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Customer Refund for Over Rate Collections + References No definition available. + Details
Name: | sjw_CustomerRefundforOverRateCollections
Namespace Prefix: | sjw_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Water Reduction Target Goal, Percentage + References No definition available. + Details
Name: | sjw_WaterReductionTargetGoalPercentage
Namespace Prefix: | sjw_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration