Summary of Significant Accounting Policies: (Policies)	3 Months Ended
Summary of Significant Accounting Policies: (Policies)	Mar. 31, 2017
Accounting Policies [Abstract]
Nature of Operations	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 261,000 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 Registrant 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 months ended March 31, 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 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 these 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. During each of the three-month periods ended March 31, 2017 and 2016, GSWC allocated to ASUS approximately $1.0 million of corporate office administrative and general costs. In addition, AWR has a $150.0 million syndicated credit facility. AWR borrows under this facility and provides funds to its subsidiaries, including GSWC, in support of their operations. The interest rate charged to GSWC and ASUS is sufficient to cover AWR’s interest cost 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 March 31, 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) 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 rate-making area as applicable. These franchise fees, which are required to be paid regardless of GSWC’s ability to collect them from its customer, are accounted for on a gross basis. GSWC’s franchise fees billed to customers and recorded as operating revenue were approximately $827,000 and $867,000 for the three months ended March 31, 2017 and 2016, respectively. When GSWC acts as an agent, and the tax is not required to be remitted if it is not collected from the customer, the taxes are accounted for on a net basis.
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, further 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 Registrant's shareholders' equity, which can impact the effective tax rate. The standard was effective January 1, 2017 and did not have a significant impact on Registrant's net earnings (