General	6 Months Ended
Jun. 30, 2011
General [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	General In the opinion of SJW Corp., the accompanying unaudited condensed consolidated financial statements contain all adjustments necessary for the fair presentation of the results for the interim periods. These adjustments consist only of normal recurring adjustments. The unaudited interim financial information has been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and in accordance with the instructions for Form 10-Q and Rule 10-01 of Regulation S-X promulgated by the Securities and Exchange Commission (the “SEC”). The Notes to Consolidated Financial Statements in SJW Corp.’s 2010 Annual Report on Form 10-K should be read with the accompanying unaudited condensed consolidated financial statements. Water sales are seasonal in nature and influenced by weather conditions. The timing of precipitation and climatic conditions can cause seasonal water consumption by customers to vary significantly. Due to the seasonal nature of the water business, the operating results for interim periods are not indicative of the operating results for a 12-month period. Revenue is generally higher in the warm, dry summer months when water usage and sales are greater, and lower in the winter months when cooler temperatures and increased rainfall curtail water usage and sales. Basic earnings per share is calculated using income available to common shareholders, divided by the weighted average number of shares outstanding during the period. The two-class method in computing basic earnings per share is not used because the number of participating securities as defined in Financial Accounting Standards Board (FASB) Accounting Standard Codification (ASC) Topic 260 - “Earning Per Share” is not significant. (The two-class method is an earnings allocation formula that determines earnings per share for each class of common stock and participating security.) Diluted earnings per share is calculated using income available to common shareholders divided by the weighted average number of shares of common stock including both shares outstanding and shares potentially issuable in connection with stock options, deferred restricted common stock awards under SJW Corp.’s Long-Term Incentive Plan (as amended, the “Incentive Plan”) and shares potentially issuable under the Employee Stock Purchase Plan (“ESPP”). For the three months ended June 30, 2011 and 2010, 2,071 and 0 anti-dilutive restricted common stock units were excluded from the dilutive earnings per share calculation, respectively. For the six months ended June 30, 2011 and 2010, 2,310 and 2,433 anti-dilutive restricted common stock units were excluded from the dilutive earnings per share calculation, respectively. The Company reclassified $2,568 and $5,106 of costs incurred to support the delivery of water from other operating expense to production costs and $1,956 and $3,885 from other operating expense to administrative and general related to customer service costs for the three and six-month periods ended June 30, 2010, respectively. In addition, the Company reclassified income taxes out of operating expense to conform to the current year presentation. These reclassifications impacted total production costs, total operating expense and operating income. The Company believes these reclassifications provide investors with better operating information and are in line with current practices of other water companies and California Public Utilities Commission (“CPUC”) guidance.

General

6 Months Ended

Jun. 30, 2011

Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]

General

In the opinion of SJW Corp., the accompanying unaudited condensed consolidated financial statements contain all adjustments necessary for the fair presentation of the results for the interim periods. These adjustments consist only of normal recurring adjustments.

The unaudited interim financial information has been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and in accordance with the instructions for Form 10-Q and Rule 10-01 of Regulation S-X promulgated by the Securities and Exchange Commission (the “SEC”). The Notes to Consolidated Financial Statements in SJW Corp.’s 2010 Annual Report on Form 10-K should be read with the accompanying unaudited condensed consolidated financial statements.

Water sales are seasonal in nature and influenced by weather conditions. The timing of precipitation and climatic conditions can cause seasonal water consumption by customers to vary significantly. Due to the seasonal nature of the water business, the operating results for interim periods are not indicative of the operating results for a 12-month period. Revenue is generally higher in the warm, dry summer months when water usage and sales are greater, and lower in the winter months when cooler temperatures and increased rainfall curtail water usage and sales.

Basic earnings per share is calculated using income available to common shareholders, divided by the weighted average number of shares outstanding during the period. The two-class method in computing basic earnings per share is not used because the number of participating securities as defined in Financial Accounting Standards Board (FASB) Accounting Standard Codification (ASC) Topic 260 - “Earning Per Share” is not significant. (The two-class method is an earnings allocation formula that determines earnings per share for each class of common stock and participating security.) Diluted earnings per share is calculated using income available to common shareholders divided by the weighted average number of shares of common stock including both shares outstanding and shares potentially issuable in connection with stock options, deferred restricted common stock awards under SJW Corp.’s Long-Term Incentive Plan (as amended, the “Incentive Plan”) and shares potentially issuable under the Employee Stock Purchase Plan (“ESPP”). For the three months ended June 30, 2011 and 2010, 2,071 and 0 anti-dilutive restricted common stock units were excluded from the dilutive earnings per share calculation, respectively. For the six months ended June 30, 2011 and 2010, 2,310 and 2,433 anti-dilutive restricted common stock units were excluded from the dilutive earnings per share calculation, respectively.

The Company reclassified $2,568 and $5,106 of costs incurred to support the delivery of water from other operating expense to production costs and $1,956 and $3,885 from other operating expense to administrative and general related to customer service costs for the three and six-month periods ended June 30, 2010, respectively. In addition, the Company reclassified income taxes out of operating expense to conform to the current year presentation. These reclassifications impacted total production costs, total operating expense and operating income. The Company believes these reclassifications provide investors with better operating information and are in line with current practices of other water companies and California Public Utilities Commission (“CPUC”) guidance.