California Water Service Group Stock	12 Months Ended
California Water Service Group Stock	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
California Water Service Group Stock	California Water Service Group Stock SJW Corp. classifies its investment in California Water Service Group as available-for-sale. On June 30, 2014, SJW Corp. sold 125,969 shares of California Water Service Group for $3,056, before fees of $10. SJW Corp. recognized a gain on the sale of the stock of approximately $2,017, tax expense of approximately $822, for a net gain of $1,195. The unrealized holding gain associated with the shares sold, that was reclassified out of accumulated other comprehensive income was $1,171 and was based on the fair value of the stock as of March 31, 2014. As of December 31, 2015, SJW Corp. held 259,151 shares of California Water Service Group. The stock is carried at quoted market price with changes in unrealized gain or loss reported, net of tax, as a component of other comprehensive income. As of December 31, 2015 and 2014, fair value of the Company's investment in California Water Service Group was $6,030 and $6,378, respectively, and would be categorized as Level 1 of the fair value hierarchy.

The entire disclosure for investments in certain debt and equity securities.