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California Water Service Group Stock (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Available for Sale Marketable Security, Shares Sold	82,340		100,000
Proceeds from Sale of Debt Securities, Available-for-sale	$ 3,398		$ 4,112
Fees Incurred on Sale of Available for Sale Securities	7		9
Available-for-sale Securities, Gross Realized Gain (Loss)	191	$ 0	104	$ 0
Available for Sales Securities, Tax on Realized Gain	53		29
Debt and Equity Securities, Gain (Loss)	$ 138		$ 75
Available for Sale Marketable Security, Shares Held	0		0

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This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

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Amount of unrealized and realized gain (loss) on investment in debt and equity securities.

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Amount of cash inflow from sale of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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