Summary of Significant Accounting Policies: (Policies)	6 Months Ended
Summary of Significant Accounting Policies: (Policies)	Jun. 30, 2017
Accounting Policies [Abstract]
Nature of Operations and Basis of Presentation	Nature of Operations: American States Water Company (“AWR”) is the parent company of Golden State Water Company (“GSWC”) and American States Utility Services, Inc. (“ASUS”) (and its subsidiaries, Fort Bliss Water Services Company (“FBWS”), Terrapin Utility Services, Inc. (“TUS”), Old Dominion Utility Services, Inc. (“ODUS”), Palmetto State Utility Services, Inc. (“PSUS”), Old North Utility Services, Inc. (“ONUS”), and Emerald Coast Utility Services ("ECUS")). The subsidiaries of ASUS are collectively referred to as the “Military Utility Privatization Subsidiaries.” GSWC is a public utility engaged principally in the purchase, production, distribution and sale of water in California serving approximately 259,000 customers. GSWC also distributes electricity in several San Bernardino County mountain communities in California serving approximately 24,000 customers through its Bear Valley Electric Service (“BVES”) division. Although GSWC has a diversified base of residential, industrial and other customers, revenues derived from commercial and residential water customers accounted for approximately 90% of total water revenues during the three and six months ended June 30, 2017 and 2016. The California Public Utilities Commission (“CPUC”) regulates GSWC’s water and electric businesses in matters including properties, rates, services, facilities and transactions by GSWC with its affiliates. AWR’s assets and operating income are primarily those of GSWC. ASUS, through its wholly owned subsidiaries, operates, maintains and performs construction activities (including renewal and replacement capital work) on water and/or wastewater systems at various United States military bases pursuant to 50-year firm fixed-price contracts. These contracts are subject to periodic price redeterminations or economic price adjustments and modifications for changes in circumstances, changes in laws and regulations and additions to the contract value for new construction of facilities at the military bases. There is no direct regulatory oversight by the CPUC over AWR or the operations, rates or services provided by ASUS or any of its wholly owned subsidiaries. Basis of Presentation: The consolidated financial statements and notes thereto are presented in a combined report filed by two separate Registrants: AWR and GSWC. References in this report to “Registrant” are to AWR and GSWC, collectively, unless otherwise specified. AWR owns all of the outstanding Common Shares of GSWC and ASUS. ASUS owns all of the outstanding Common Shares of the Military Utility Privatization Subsidiaries. The consolidated financial statements of AWR include the accounts of AWR and its subsidiaries, all of which are wholly owned. These financial statements are prepared in conformity with accounting principles generally accepted in the United States of America. Inter-company transactions and balances have been eliminated in the AWR consolidated financial statements. The consolidated financial statements included herein have been prepared by Registrant, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). The December 31, 2016 condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by generally accepted accounting principles ("GAAP") in the United States of America. The preparation of the consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. In the opinion of management, all adjustments consisting of normal, recurring items and estimates necessary for a fair statement of the results for the interim periods have been made. It is suggested that these consolidated financial statements be read in conjunction with the consolidated financial statements and the notes thereto included in the Form 10-K for the year ended December 31, 2016 filed with the SEC.
GSWC's Related Party Transactions	GSWC's Related Party Transactions: GSWC and ASUS provide and/or receive various support services to and from their parent, AWR, and among themselves. GSWC also allocates certain corporate office administrative and general costs to its affiliate, ASUS, using allocation factors approved by the CPUC. GSWC allocated corporate office administrative and general costs to ASUS of approximately $1.0 million during the three months ended June 30, 2017 and 2016, respectively, and approximately $2.0 million during the six months ended June 30, 2017 and 2016, respectively. In addition, AWR has a $150.0 million syndicated credit facility. AWR borrows under this facility and provides funds to its subsidiaries, GSWC and ASUS, in support of their operations. As of June 30, 2017, there was $44.0 million outstanding under this facility. The interest rate charged to GSWC and ASUS is sufficient to cover AWR’s interest expense under the credit facility. In October 2015, AWR issued interest-bearing promissory notes (the "Notes") to GSWC and ASUS for $40 million and $10 million, respectively, which expire on May 23, 2018. Under the terms of these Notes, AWR may borrow from GSWC and ASUS amounts up to $40 million and $10 million, respectively, for working capital purposes. AWR agrees to pay any unpaid principal amounts outstanding under these notes, plus accrued interest. As of June 30, 2017 and 2016, there were no amounts outstanding under these notes.
Sales and Use Taxes	Sales and Use Taxes: GSWC bills certain sales and use taxes levied by state or local governments to its customers. Included in these sales and use taxes are franchise fees, which GSWC pays to various municipalities (based on ordinances adopted by these municipalities) in order to use public rights of way for utility purposes. GSWC bills these franchise fees to its customers based on a CPUC-authorized rate for each ratemaking area as applicable. These franchise fees, which are required to be paid regardless of GSWC’s ability to collect them from its customers, are accounted for on a gross basis. GSWC’s franchise fees billed to customers and recorded as operating revenue were approximately $937,000 and $1.0 million for the three months ended June 30, 2017 and 2016, respectively, and $1.8 million and $1.9 million for the six months ended June 30, 2017 and 2016, respectively. When GSWC acts as an agent, and a tax is not required to be remitted if it is not collected from customers, the tax is accounted for on a net basis. Depending on the states in which their operations are conducted, the Military Utility Privatization Subsidiaries are also subject to certain state non-income tax assessments generally computed on a “gross receipts” or “gross revenues” basis. These non-income tax assessments are required to be paid regardless of whether the U.S. government reimburses these assessments under the 50-year contracts. The non-income tax assessments are accounted for on a gross basis and totaled $72,000 and $84,000 during the three months ended June 30, 2017 and 2016, respectively, and $121,000 and $146,000 for the six months ended June 30, 2017 and 2016, respectively.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements: In March 2016, the FASB issued Accounting Standard Update 2016-09, Improvements to Employee Share-Based Payment Accounting, which amends ASC Topic 718, Compensation - Stock Compensation. Under the new guidance, the tax effects related to share-based payments at settlement (or expiration) will be required to be recorded through the income statement rather than through equity, therefore increasing the volatility of income tax expense. The new standard also removes the requirement to delay recognition of a windfall tax benefit until an employer reduces its current taxes payable. It also permits entities to make an accounting policy election for the impact of forfeitures on the recognition of expense for shared-based payment awards. Income tax benefits in excess of compensation costs or tax deficiencies for share-based compensation are recorded to the income tax provision, instead of to shareholders' equity, which can impact the effective tax rate. Registrant adopted the new standard effective January 1, 2017 (see Note 6). On a prospective basis, the excess tax benefits are classified as an operating activity along with other income tax cash flows on the statement of cash flows. In May 2014, the FASB issued updated accounting guidance on revenue recognition. Under this guidance, an entity recognizes revenue when it transfers promised goods or services to customers in an amount that reflects what the entity expects in exchange for the goods or services. The guidance also requires more detailed disclosures to enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, and adoption is not permitted earlier than 2017. The guidance allows entities to select one of two methods of adoption, either the full retrospective approach, meaning the guidance would be applied to all periods presented, or modified retrospective approach, meaning the cumulative effect of applying the guidance would be recognized as an adjustment to opening retained earnings at January 1, 2018, along with providing certain additional disclosures. Registrant intends to use the modified retrospective approach beginning January 1, 2018. Management continues to assess all potential impacts of the standard, and does not believe the new standard will have a material impact on GSWC's revenues for water and electric services. In instances where construction contracts contain more than one distinct good or service, as defined by the standard, the new standard may affect the timing of when AWR recognizes contracted services revenue. In February 2016, the FASB issued a new lease accounting standard, Leases (ASC 842). Under the new guidance, lessees will recognize a right-of-use asset and a lease liability for virtually all leases (other than leases that meet the definition of a short-term lease). For income statement purposes, leases will be classified as either operating or finance. Operating leases will result in straight-line expense while finance leases will result in a front-loaded expense pattern. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Management has not yet determined the effect of the standard on Registrant's financial statements. In March 2017, the FASB issued Accounting Standards Update 2017-07, Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, which changes the financial statement presentation of the cost of defined benefit pension plans and other retirement benefits. Under current GAAP, the components of net benefit cost for retirement plans (such as service cost, interest cost, expected return on assets, and the amortization of various deferred items), are aggregated as operating costs for financial statement presentation purposes. Under the new guidance, the service cost component will continue to be presented as operating costs, while all other components of net benefit cost will be presented outside of operating income. The new guidance is effective for annual and interim periods beginning after December 15, 2017, with early adoption permitted. The Company is currently evaluating the impact of this new standard on its statements of income, and expects to adopt the standard beginning in 2018. In August 2016, the FASB issued updated accounting guidance on the classification of certain cash receipts and cash payments in the statement of cash flows, which is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. This guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017, and early adoption is permitted. Registrant is currently evaluating the impact of this new standard on its consolidated cash flow statement. In May 2017, the FASB issued Accounting Standards Update 2017-09, Compensation-—Stock Compensation (Topic 718): Scope of Modification Accounting, which clarifies existing guidance on when to account for the effect of a modification of a share-based payment award. Under the new guidance, the effects of a modification should be accounted for unless all of the following are met: (i) the modification does not change the fair value of the award; (ii) the vesting conditions are the same before and after the modification, and; (iii) the classification of the award as an equity instrument or as a liability instrument is the same classification immediately before the modification. For Registrant, these amendments will be effective January 1, 2018 and will be applied prospectively to an award modified on or after January 1, 2018. Registrant does not expect the adoption of this guidance to have a significant impact on its consolidated financial statements.