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Summary of Significant Accounting Policies (Narrative) (Details) | 12 Months Ended
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Dec. 31, 2015 mi² people_served
Acequia Water Supply Corporation [Member] |
Public Utilities General Disclosures [Line Items] |
Ownership percentage in Acequia Water Supply Corporation | 25.00%
Minimum [Member] |
Public Utilities General Disclosures [Line Items] |
Service area in square miles | mi² | 243
Sales [Member] | Product Concentration Risk [Member] |
Public Utilities General Disclosures [Line Items] |
Percentage of revenue derived from sales of water to business and residential customers | 93.00%
San Jose Water Company [Member] |
Public Utilities General Disclosures [Line Items] |
Number of people served | 1,000,000
SJWTX,Inc. dba Canyon Lake Water Supply Corporation [Member] |
Public Utilities General Disclosures [Line Items] |
Number of people served | 37,000
444 West Santa Clara Street, L.P. [Member] |
Public Utilities General Disclosures [Line Items] |
Limited partership interest percentage | 70.00%

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