Summary of Significant Accounting Policies:	9 Months Ended
Sep. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies 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, Inc. ("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 nine months ended September 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 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. On September 29, 2017, ASUS was awarded a new 50-year contract by the U.S. government to operate, maintain, and provide construction management services for the water distribution and wastewater collection and treatment facilities at Fort Riley, a United States Army installation located in Kansas. The initial value of the contract is approximately $601 million over the 50-year period and is subject to annual economic price adjustments. This initial value is also subject to adjustment based on the results of a joint inventory of assets to be performed during the transition period. ASUS will assume operations at Fort Riley following the completion of a six-to-twelve-month transition period. 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 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 each of the three months ended September 30, 2017 and 2016, and approximately $3.0 million during each of the nine months ended September 30, 2017 and 2016. 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 September 30, 2017, there was $46.0 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 September 30, 2017 and 2016, there were no amounts outstanding under these notes. 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 $1.0 million and $1.1 million for the three months ended September 30, 2017 and 2016, respectively, and $2.8 million and $3.0 million for the nine months ended September 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 $55,000 and $62,000 during the three months ended September 30, 2017 and 2016, respectively, and $177,000 and $209,000 for the nine months ended September 30, 2017 and 2016, respectively. Recently Issued Accounting Pronouncements: In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standard Update 2016-09, Improvements to Employee Share-Based Payment Accounting, which amends Accounting Standards Codification ("ASC") Topic 718, Compensation - Stock Compensation. Under the new guidance, the tax effects related to share-based payments at settlement (or expiration) are required to be recorded through the income statement rather than through equity, therefore increasing the volatility of income tax expense. The new standard also removed 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 Accounting Standard Update 2014-09, Revenue from Contracts with Customers (Topic 606). 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 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 to prior periods would be recognized as an adjustment to opening retained earnings at January 1, 2018, and requires 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 to-date has not identified any material impact on earnings or material impacts on how Registrant recognizes revenue. The previously disclosed issue regarding contributions in aid of construction (CIAC) has been resolved, subject to finalization of implementation guidance. GSWC does not expect CIAC to be in the scope of the guidance and, therefore, will continue to record CIAC as liabilities and as a reduction to rate base. The guidance will also require enhanced disclosures, including a disaggregated revenue disclosure from contracts with customers. Some revenue arrangements which meet the definition of alternative revenue programs under ASC 980 Regulated Operations, such as GSWC's Water Revenue Adjustment Mechanism and Base Revenue Requirement Adjustment Mechanisms, are excluded from the scope of the new standard and, therefore, will be disclosed separately from revenues from contracts with customers under the new guidance. 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 for the costs 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 also limits any capitalization of net periodic benefits cost to the service cost component. The new guidance is effective for annual and interim periods beginning after December 15, 2017, with early adoption permitted. Registrant is currently evaluating the impact of this new standard on its financial statements, and to-date has not identified a material impact on its consolidated financial statements. Registrant will adopt the standard beginning in 2018. In August 2016, the FASB issued Accounting Standards Update 2016-15, Statement of Cash Flows (Topic 230) Classification of Certain Cash Receipts and Cash Payments, 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 does not expect the adoption of this new standard to have a significant impact on its cash flow statements. In May 2017, the FASB issued Accounting Standards Update 2017-10, Service Concession Arrangements (Topic 853): Determining the Customer of the Operation Services, which addresses the accounting for a service concession arrangement. A service concession arrangement is an arrangement between a grantor and an operating entity for which the terms provide that the operating entity will operate the grantor’s infrastructure (such as water and wastewater facilities) for a specified period of time. Under this guidance, revenue from service concession arrangements will be accounted for in accordance with Topic 605 on revenue recognition, or Topic 606 on revenue from contracts with customers, as applicable. In addition, the infrastructure that is the subject of a service concession arrangement will not be recognized as property, plant, and equipment of the operating entity. For Registrant, the effective date of this new guidance will be January 1, 2018, the same date that Registrant will adopt the provisions under Topic 606. Registrant does not expect the adoption of the guidance on service concession arrangements to have a significant impact on its consolidated financial statements.

Summary of Significant Accounting Policies

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, Inc. ("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 nine months ended September 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 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.

On September 29, 2017, ASUS was awarded a new 50-year contract by the U.S. government to operate, maintain, and provide construction management services for the water distribution and wastewater collection and treatment facilities at Fort Riley, a United States Army installation located in Kansas. The initial value of the contract is approximately $601 million over the 50-year period and is subject to annual economic price adjustments. This initial value is also subject to adjustment based on the results of a joint inventory of assets to be performed during the transition period. ASUS will assume operations at Fort Riley following the completion of a six-to-twelve-month transition period.

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 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 each of the three months ended September 30, 2017 and 2016, and approximately $3.0 million during each of the nine months ended September 30, 2017 and 2016. 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 September 30, 2017, there was $46.0 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 September 30, 2017 and 2016, there were no amounts outstanding under these notes.

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 $1.0 million and $1.1 million for the three months ended September 30, 2017 and 2016, respectively, and $2.8 million and $3.0 million for the nine months ended September 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 $55,000 and $62,000 during the three months ended September 30, 2017 and 2016, respectively, and $177,000 and $209,000 for the nine months ended September 30, 2017 and 2016, respectively.

Recently Issued Accounting Pronouncements: In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standard Update 2016-09, Improvements to Employee Share-Based Payment Accounting, which amends Accounting Standards Codification ("ASC") Topic 718, Compensation - Stock Compensation. Under the new guidance, the tax effects related to share-based payments at settlement (or expiration) are required to be recorded through the income statement rather than through equity, therefore increasing the volatility of income tax expense. The new standard also removed 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 Accounting Standard Update 2014-09, Revenue from Contracts with Customers (Topic 606). 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 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 to prior periods would be recognized as an adjustment to opening retained earnings at January 1, 2018, and requires 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 to-date has not identified any material impact on earnings or material impacts on how Registrant recognizes revenue. The previously disclosed issue regarding contributions in aid of construction (CIAC) has been resolved, subject to finalization of implementation guidance. GSWC does not expect CIAC to be in the scope of the guidance and, therefore, will continue to record CIAC as liabilities and as a reduction to rate base. The guidance will also require enhanced disclosures, including a disaggregated revenue disclosure from contracts with customers. Some revenue arrangements which meet the definition of alternative revenue programs under ASC 980 Regulated Operations, such as GSWC's Water Revenue Adjustment Mechanism and Base Revenue Requirement Adjustment Mechanisms, are excluded from the scope of the new standard and, therefore, will be disclosed separately from revenues from contracts with customers under the new guidance.

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 for the costs 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 also limits any capitalization of net periodic benefits cost to the service cost component. The new guidance is effective for annual and interim periods beginning after December 15, 2017, with early adoption permitted. Registrant is currently evaluating the impact of this new standard on its financial statements, and to-date has not identified a material impact on its consolidated financial statements. Registrant will adopt the standard beginning in 2018.

In August 2016, the FASB issued Accounting Standards Update 2016-15, Statement of Cash Flows (Topic 230)

Classification of Certain Cash Receipts and Cash Payments, 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 does not expect the adoption of this new standard to have a significant impact on its cash flow statements.

In May 2017, the FASB issued Accounting Standards Update 2017-10, Service Concession Arrangements (Topic 853): Determining the Customer of the Operation Services, which addresses the accounting for a service concession arrangement. A service concession arrangement is an arrangement between a grantor and an operating entity for which the terms provide that the operating entity will operate the grantor’s infrastructure (such as water and wastewater facilities) for a specified period of time. Under this guidance, revenue from service concession arrangements will be accounted for in accordance with Topic 605 on revenue recognition, or Topic 606 on revenue from contracts with customers, as applicable. In addition, the infrastructure that is the subject of a service concession arrangement will not be recognized as property, plant, and equipment of the operating entity. For Registrant, the effective date of this new guidance will be January 1, 2018, the same date that Registrant will adopt the provisions under Topic 606. Registrant does not expect the adoption of the guidance on service concession arrangements to have a significant impact on its consolidated financial statements.