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Derivative Instruments (Tables) | 9 Months Ended
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Sep. 30, 2018
Golden State Water Company |
Derivative Instruments, Gain (Loss) [Line Items] |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation | The following table presents changes in the fair value of GSWC’s Level 3 derivatives for the three and nine months ended September 30, 2018 and 2017:
|  | For The Three Months Ended September 30, |  | For The Nine Months Ended September 30,
(dollars in thousands) |  | 2018 |  | 2017 |  | 2018 |  | 2017
Fair value at beginning of the period |  | $ | (1,710 | ) |  | $ | (4,493 | ) |  | $ | (2,941 | ) |  | $ | (4,901 | )
Unrealized gain on purchased power contracts |  | 567 |  |  | 656 |  |  | 1,798 |  |  | 1,064 |
Fair value at end of the period |  | $ | (1,143 | ) |  | $ | (3,837 | ) |  | $ | (1,143 | ) |  | $ | (3,837 | )

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- Definition Tabular disclosure of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset) using recurring unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19279-110258 + Details
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