Contingencies:	3 Months Ended
Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies: Condemnation of Properties: The laws of the State of California provide for the acquisition of public utility property by governmental agencies through their power of eminent domain, also known as condemnation, where doing so is necessary and in the public interest. In addition, these laws provide: (i) that the owner of utility property may contest whether the condemnation is actually necessary and in the public interest, and (ii) that the owner is entitled to receive the fair market value of its property if the property is ultimately taken. Claremont System: On November 4, 2014, voters in the City of Claremont ("Claremont" or "the City") approved a measure authorizing the issuance of $135 million in water revenue bonds by the City to finance the acquisition of the Claremont water system. On December 9, 2014, the City filed an eminent domain lawsuit against GSWC. GSWC has the ability to legally challenge the government's right to take its property. GSWC does not believe the seizure is necessary and intends to vigorously defend against the potential condemnation. In January 2015, GSWC filed a motion on the grounds that Claremont failed to follow proper procedures when it filed its eminent domain lawsuit, among other things. On April 30, 2015, the Los Angeles Superior Court granted GSWC's motion. The City has the right to file an amended complaint. At this time, management cannot predict the outcome of the eminent domain proceeding. The Claremont water system has a net book value of approximately $47.4 million. GSWC serves approximately 11,000 customers in Claremont. Ojai System: In March 2013, Casitas Municipal Water District ("CMWD") passed resolutions under the Mello-Roos Community Facilities District Act of 1982 ("Mello-Roos Act") authorizing the establishment of a Community Facilities District, and the issuance of bonds to finance the potential acquisition of GSWC’s Ojai system by eminent domain. GSWC filed a petition in the Superior Court and eventually the Court of Appeals in Ventura County, which, among other things, challenged the legality of CMWD’s effort to utilize the Mello-Roos Act to acquire property by eminent domain and to fund legal and expert costs of the planned condemnation. On April 14, 2015, the California Court of Appeals affirmed a prior court's ruling allowing the use of Mello-Roos funding. On April 29, 2015, GSWC file a petition for rehearing at the Appellate Court level in Ojai. Ojai FLOW ("Friends of Locally Owned Water") members were also granted class status by the Superior Court to later file action against GSWC should they be able to prove GSWC’s motions delayed condemnation action and resulted in higher costs for Ojai residents should the system be ultimately taken. GSWC serves approximately 3,000 customers in Ojai. Apple Valley System: The Town of Apple Valley has indicated they plan to commence a condemnation action against Park Water Company who serves most of the Town, but has not made a similar indication against GSWC. GSWC serves approximately 2,900 customers in the Town of Apple Valley. Artesia System: On October 13, 2014, the City of Artesia's City Council approved a request for a feasibility study on the potential acquisition of GSWC's water system in Artesia. GSWC serves approximately 3,300 customers in Artesia. Environmental Clean-Up and Remediation: GSWC has been involved in environmental remediation and clean-up at a plant site ("Chadron Plant") that contained an underground storage tank which was used to store gasoline for its vehicles. This tank was removed from the ground in July 1990 along with the dispenser and ancillary piping. Since then, GSWC has been involved in various remediation activities at this site. Analysis indicates that offsite monitoring wells may also be necessary to document effectiveness of remediation. As of March 31, 2015, the total spent to clean-up and remediate GSWC’s plant facility was approximately $4.6 million, of which $1.5 million has been paid by the State of California Underground Storage Tank Fund. Amounts paid by GSWC have been included in rate base and approved by the CPUC for recovery. As of March 31, 2015, GSWC has a regulatory asset and an accrued liability for the estimated additional cost of $1.4 million to complete the clean-up at the site. The estimate includes costs for two years of continued activities of groundwater cleanup and monitoring, future soil treatment and site closure related activities. The ultimate cost may vary as there are many unknowns in remediation of underground gasoline spills and this is an estimate based on currently available information. Management also believes it is probable that the estimated additional costs will be approved in rate base by the CPUC. Other Litigation: Registrant is also subject to other ordinary routine litigation incidental to its business. Management believes that rate recovery, proper insurance coverage and reserves are in place to insure against property, general liability and workers’ compensation claims incurred in the ordinary course of business. Registrant is unable to predict an estimate of the loss, if any, resulting from any pending suits or administrative proceedings.

Contingencies:

Condemnation of Properties:

The laws of the State of California provide for the acquisition of public utility property by governmental agencies through their power of eminent domain, also known as condemnation, where doing so is necessary and in the public interest. In addition, these laws provide: (i) that the owner of utility property may contest whether the condemnation is actually necessary and in the public interest, and (ii) that the owner is entitled to receive the fair market value of its property if the property is ultimately taken.

Claremont System:

On November 4, 2014, voters in the City of Claremont ("Claremont" or "the City") approved a measure authorizing the issuance of $135 million in water revenue bonds by the City to finance the acquisition of the Claremont water system. On December 9, 2014, the City filed an eminent domain lawsuit against GSWC. GSWC has the ability to legally challenge the government's right to take its property. GSWC does not believe the seizure is necessary and intends to vigorously defend against the potential condemnation. In January 2015, GSWC filed a motion on the grounds that Claremont failed to follow proper procedures when it filed its eminent domain lawsuit, among other things. On April 30, 2015, the Los Angeles Superior Court granted GSWC's motion. The City has the right to file an amended complaint. At this time, management cannot predict the outcome of the eminent domain proceeding. The Claremont water system has a net book value of approximately $47.4 million. GSWC serves approximately 11,000 customers in Claremont.

Ojai System:

In March 2013, Casitas Municipal Water District ("CMWD") passed resolutions under the Mello-Roos Community Facilities District Act of 1982 ("Mello-Roos Act") authorizing the establishment of a Community Facilities District, and the issuance of bonds to finance the potential acquisition of GSWC’s Ojai system by eminent domain. GSWC filed a petition in the Superior Court and eventually the Court of Appeals in Ventura County, which, among other things, challenged the legality of CMWD’s effort to utilize the Mello-Roos Act to acquire property by eminent domain and to fund legal and expert costs of the planned condemnation. On April 14, 2015, the California Court of Appeals affirmed a prior court's ruling allowing the use of Mello-Roos funding. On April 29, 2015, GSWC file a petition for rehearing at the Appellate Court level in Ojai. Ojai FLOW ("Friends of Locally Owned Water") members were also granted class status by the Superior Court to later file action against GSWC should they be able to prove GSWC’s motions delayed condemnation action and resulted in higher costs for Ojai residents should the system be ultimately taken. GSWC serves approximately 3,000 customers in Ojai.

Apple Valley System:

The Town of Apple Valley has indicated they plan to commence a condemnation action against Park Water Company who serves most of the Town, but has not made a similar indication against GSWC. GSWC serves approximately 2,900 customers in the Town of Apple Valley.

Artesia System:

On October 13, 2014, the City of Artesia's City Council approved a request for a feasibility study on the potential acquisition of GSWC's water system in Artesia. GSWC serves approximately 3,300 customers in Artesia.

Environmental Clean-Up and Remediation:

GSWC has been involved in environmental remediation and clean-up at a plant site ("Chadron Plant") that contained an underground storage tank which was used to store gasoline for its vehicles. This tank was removed from the ground in July 1990 along with the dispenser and ancillary piping. Since then, GSWC has been involved in various remediation activities at this site. Analysis indicates that offsite monitoring wells may also be necessary to document effectiveness of remediation.

As of March 31, 2015, the total spent to clean-up and remediate GSWC’s plant facility was approximately $4.6 million, of which $1.5 million has been paid by the State of California Underground Storage Tank Fund. Amounts paid by GSWC have been included in rate base and approved by the CPUC for recovery. As of March 31, 2015, GSWC has a regulatory asset and an accrued liability for the estimated additional cost of $1.4 million to complete the clean-up at the site. The estimate includes costs for two years of continued activities of groundwater cleanup and monitoring, future soil treatment and site closure related activities. The ultimate cost may vary as there are many unknowns in remediation of underground gasoline spills and this is an estimate based on currently available information. Management also believes it is probable that the estimated additional costs will be approved in rate base by the CPUC.

Other Litigation:

Registrant is also subject to other ordinary routine litigation incidental to its business. Management believes that rate recovery, proper insurance coverage and reserves are in place to insure against property, general liability and workers’ compensation claims incurred in the ordinary course of business. Registrant is unable to predict an estimate of the loss, if any, resulting from any pending suits or administrative proceedings.