California Water Service Group Stock (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Available for Sale Marketable Security, Shares Sold	17,660
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds	$ 716
Fees Incurred on Sale of Available for Sale Securities	2
Available-for-sale Securities, Gross Realized Gain (Loss)	(87)	$ 0
Available for Sales Securities, Tax on Realized Gain	(24)
Gain (Loss) on Sale of Securities, Net	$ (63)
Available for Sale Marketable Security, Shares Held	82,340

Available for Sale Marketable Security, Shares Held

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- Definition

Available for Sale Marketable Security, Shares Sold

+ References

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- Definition

Available for Sales Securities, Tax on Realized Gain

+ References

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- Definition

Fees Incurred on Sale of Available for Sale Securities

+ References

No definition available.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563

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- Definition

The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period.

+ References

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- Definition

The net gain (loss) realized from the sale, exchange, redemption, or retirement of securities, not separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(h))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.3)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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- References

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