(Gain) loss on investments held in a trust (Gain) loss on investments held in a trust Unrealized Gain (Loss) on Investments Dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] GOLDEN STATE WATER COMPANY GSWC Golden State Water Company [Member] Golden State Water Company [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] Total capitalization Capitalization, Long-Term Debt and Equity Low income rate assistance balancing accounts Low income rate assistance balancing accounts [Member] Low income rate assistance balancing accounts Commodity Contract Commodity Contract [Member] Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Award Timing Predetermined Award Timing Predetermined [Flag] Related Party Transaction [Axis] Related Party Transaction [Axis] Sale of Stock, remaining available for sale Sale of Stock, remaining available for sale Sale of Stock, remaining available for sale under the ATM equity program Asset Class [Axis] Asset Class [Axis] Entity File Number Entity File Number Water Water [Member] Tabular List, Table Tabular List [Table Text Block] Basic Earnings Per Common Share Earnings Per Share, Basic [Abstract] Schedule of Regulatory Assets and Liabilities [Table] Schedule of Regulatory Assets and Liabilities [Table] A table of assets and liabilities that are created when regulatory agencies permit public utilities to defer certain costs and recognition of certain revenues that are included in rate-setting to the balance sheet. Unbilled receivable Unbilled Contracts Receivable Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Accounts payable Increase (Decrease) in Accounts Payable PFAS Contamination Litigation Proceeds Memorandum Account PFAS Contamination Litigation Proceeds Memorandum Account [Member] PFAS Contamination Litigation Proceeds Memorandum Account Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Measurement Basis [Axis] Measurement Basis [Axis] Basic Earnings Per Common Share (in dollars per share) Basic earnings per Common Share (in dollars per share) Earnings Per Share, Basic Adjustment to Compensation: Adjustment to Compensation [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Total other credits Liabilities, Other Than Long-Term Debt Related To Capitalization, Noncurrent Liabilities, Other Than Long-Term Debt Related To Capitalization, Noncurrent Revenues Revenue from Contract with Customer [Text Block] Property, Plant and Equipment Utilities Property Plant and Equipment Gross [Abstract] -- None. No documentation exists for this element. -- Unbilled revenue — receivable from the U.S. government (Note 2) Unbilled Contracts Receivable From U S Government Unbilled Contracts Receivable From U S Government Schedule of reporting segments information Schedule of Segment Reporting Information, by Segment [Table Text Block] Revenue, remaining performance obligation, amount Revenue, Remaining Performance Obligation, Amount Adjustment to Compensation, Amount Adjustment to Compensation Amount Concentration risk, percentage Concentration Risk, Percentage Pension Benefits Pension Plan [Member] Stock-based compensation expense Share-Based Payment Arrangement, Noncash Expense Employee Stock Option Share-Based Payment Arrangement, Option [Member] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Litigation settlement, amount awarded Litigation Settlement, Amount Awarded from Other Party Total common shareholders’ equity Beginning balances Ending balances Equity, Attributable to Parent Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Water Regulated Operating Revenue, Water Insider Trading Policies and Procedures [Line Items] Public Utilities, Regulatory Proceeding [Domain] Public Utilities, Regulatory Proceeding [Domain] Common Stock, Shares Authorized (in shares) Common Stock, Shares Authorized Issuance of Common Shares from an at-the-market program, net of issuance costs (in shares) Stock Issued During Period, Shares, New Issues Current Assets Assets, Current [Abstract] Total Capitalization and Liabilities Liabilities and Equity Electric: Electric Service Utility Operations [Member] Represents the electric service utility operations of the entity. Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] CAPITALIZATION AND LIABILITIES Liabilities and Equity [Abstract] Cover [Abstract] Cover [Abstract] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Maximum Maximum [Member] Capital additions Segment, Expenditure, Addition to Long-Lived Assets Contracted services: Contracted services: Contracted Services [Member] Represents the contracted services unit of the entity. Accounting Policies [Abstract] Accounting Policies [Abstract] Public Utility [Axis] Public Utility [Axis] Restricted Stock Restricted Stock [Member] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Pay vs Performance Disclosure [Line Items] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Income before income tax expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Golden State Water Company and Bear Valley Electric Service Inc. Golden State Water Company and Bear Valley Electric Service Inc. [Member] Golden State Water Company and Bear Valley Electric Service Inc. Schedule of estimates of the fair value of long-term debt Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Other Other Liabilities, Noncurrent Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Regulatory adjustment — deferred Two-Way Pension balancing accounts Two-Way Pension balancing accounts Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Name Measure Name Description of derivative activity volume Derivative Activity Volume Derivative Activity Volume Operating lease liabilities Operating Lease, Liability, Current Effective income tax rate Effective Income Tax Rate [Line Items] -- None. No documentation exists for this element. -- Advances for construction Advances For Construction Advances For Construction Deferred income taxes Deferred Income Tax Liabilities, Net Long-term debt — current Other Notes Payable, Current Document Fiscal Period Focus Document Fiscal Period Focus Receivable from the U.S. government (Note 2) Accounts Receivable from U S Government Net, Current This element represents the amount, at the balance sheet date, current portion of receivables that are derived from government contracts. Award Timing Method Award Timing Method [Text Block] Litigation Case [Domain] Litigation Case [Domain] Alternative revenues program Alternative revenues program [Member] Alternative revenues program [Member] Award Type [Axis] Award Type [Axis] AWR AWR Parent Company [Member] Utility Plant [Domain] Utility Plant [Domain] Legal Entity [Axis] Legal Entity [Axis] Total Assets Assets Other regulatory liabilities Other regulatory liabilities [Member] Other regulatory liabilities Cash Flows From Investing Activities: Cash Provided by (Used in) Investing Activity, Continuing Operation [Abstract] Deferred Income Tax Charge Deferred Income Tax Charge [Member] Trading Symbol Trading Symbol Regulatory Liability [Axis] Regulatory Liability [Axis] Issuances of Common Shares under stock-based compensation plans (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture BVES Bear Valley Electric Service, Inc. [Member] Bear Valley Electric Service, Inc. Entity Address, City or Town Entity Address, City or Town Other segment items income (expense) Segment Reporting, Other Segment Item, Amount Concentration Risk Type [Axis] Concentration Risk Type [Axis] Period of fixed price contracts to operate and maintain water systems at various military bases Period of Fixed Price Contracts to Operate and Maintain Water Systems at Various Military Bases Represents the period of fixed price contracts to operate and maintain the water and/or wastewater systems at various military bases. Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Refunds on advances for construction Payment for Advance for Construction, Investing Activity Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Entity Emerging Growth Company Entity Emerging Growth Company Entity Common Stock, Shares Outstanding (in shares) Entity Common Stock, Shares Outstanding Accrued pension and other postretirement benefits Increase (Decrease) in Obligation, Pension and Other Postretirement Benefits Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Related Party Related Party [Member] Common Stock, Shares, Outstanding (in shares) Common Stock, Shares, Outstanding Regulatory Matters Schedule of Regulatory Assets and Liabilities [Text Block] Provision for doubtful accounts Accounts Receivable, Credit Loss Expense (Reversal) Contributions in aid of construction – net Contributions In Aid Construction, Net Contributions In Aid Construction, Net ASUS American States Utility Services [Member] Represents activity related to American States Utility Services, Inc. (ASUS). PEO PEO [Member] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Non-cash transactions: Noncash Investing and Financing Items [Abstract] Interest income Investment Income, Interest Related Party and Intercompany Transactions Related Party Transactions [Policy Text Block] Related Party Transactions Materials and supplies Increase (Decrease) in Materials and Supplies Changes in assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Utilities Operating Expense, Total Utilities Operating Expense Prepayments and other current assets Prepaid Expense and Other Assets, Current Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Income tax expense Income Tax Expense (Benefit) Other accounts receivable, allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Other, Current This element represents the valuation allowance for other receivables not separately presented elsewhere in the balance sheet, within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible. Accounting Policies [Table] Accounting Policies [Table] Schedule detailing accounting policies of the entity. Income taxes payable Taxes Payable, Current Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Environmental Clean-Up and Remediation Environmental Issue [Member] Product and Service [Domain] Product and Service [Domain] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Customer Concentration Risk Customer Concentration Risk [Member] Total Property, Plant and Equipment, Gross Parent Parent [Member] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Income taxes receivable/payable Increase (Decrease) in Income Taxes Schedule of reconciliation of Registrant's net income and weighted average Common Shares outstanding for calculating diluted net income per share Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Table Text Block] City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Restricted stock units outstanding (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Contract with Customer, Asset and Liability Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Administrative and general General and Administrative Expense Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Net cash provided (used) Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Add: Addition [Abstract] -- None. No documentation exists for this element. -- Amortization of actuarial (gain) loss Defined Benefit Plan, Amortization of Gain (Loss) Subsequent Event Subsequent Event [Member] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Derivative instrument memorandum account (Note 5) Gain (Loss) on Derivative Instruments [Member] Equity Components [Axis] Equity Components [Axis] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Tyco Tyco [Member] Tyco Number of reportable segments Number of Reportable Segments Net regulatory Assets Net Regulatory Assets Fair value, net derivative liability Fair value at beginning of the period Fair value at end of the period Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Other Performance Measure, Amount Other Performance Measure, Amount Regulatory liabilities Regulatory Liability, Noncurrent Entity Address, State or Province Entity Address, State or Province Dividends on Common Shares Dividends, Common Stock Total current liabilities Liabilities, Current Net change in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation 2023/2024 General Rate Case Memorandum accounts ( unbilled revenue) 2023/2024 General Rate Case Memorandum accounts ( unbilled revenue) [Member] 2023/2024 General Rate Case Memorandum accounts ( unbilled revenue) Unamortized investment tax credits Accumulated Deferred Investment Tax Credit Derivative Instrument [Axis] Derivative Instrument [Axis] Individual: Individual [Axis] Entities [Table] Entities [Table] Entity [Domain] Entity [Domain] Net cash provided (used) Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Revenue, remaining performance obligation, expected timing of satisfaction, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Bay State Utility Service LLC (" BSUS") Bay State Utility Service LLC (" BSUS") [Member] Bay State Utility Service LLC (" BSUS") Document Fiscal Year Focus Document Fiscal Year Focus Nature of Operations and Basis of Presentation Basis of Accounting, Policy [Policy Text Block] 2022/2023 general rate case memorandum accounts (unbilled revenue) 2022/2023 general rate case memorandum accounts (unbilled revenue) [Member] Discloses the amount of regulatory assets and liabilities pertaining to the general rate case memorandum accounts. Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Repayments of long-term debt Repayments of Long-Term Debt ETRs ( as a percent) Effective Income Tax Rate Reconciliation, Percent Entity Interactive Data Current Entity Interactive Data Current Cash Flows From Operating Activities: Cash Provided by (Used in) Operating Activity, Continuing Operation [Abstract] Carrying Amount Reported Value Measurement [Member] Property and other taxes Taxes, Miscellaneous Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Other Other Products and Services [Member] Other Products and Services [Member] Business Segments Segment Reporting Disclosure [Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Regulatory asset not accruing carrying costs Regulatory Asset Not Accruing Carrying Costs Represents the regulatory asset not accruing carrying costs as of the balance sheet date. Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Schedule of components of net periodic benefit costs, before allocation to the overhead pool, for Registrant's pension plan, postretirement plan, and SERP Schedule of Net Benefit Costs [Table Text Block] Commercial paper, term Investment Term Represents the term associated with a fixed-term security. Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Depreciation and amortization Depreciation, Depletion and Amortization Retained Earnings Retained Earnings, Unappropriated [Member] Other Other Assets, Noncurrent Accrued interest Interest Payable, Current Entity Central Index Key Entity Central Index Key PEO Name PEO Name Diluted: Earnings Per Share, Diluted, Two Class Method [Abstract] Total operating revenues Total operating revenues Revenues Sale of stock, consideration received on transaction Sale of Stock, Consideration Received on Transaction Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Fair value of financial instruments Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Wildfire mitigation and other fire prevention related costs memorandum accounts Wildfire mitigation and other fire prevention related costs memorandum accounts [Member] Wildfire mitigation and other fire prevention related costs memorandum accounts Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Schedule of reconciliation of Registrant's net income and weighted average Common Shares outstanding for calculating basic net income per share Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table Text Block] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Arrangement Duration Trading Arrangement Duration Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Fair Value of Financial Instruments Financial Instruments Disclosure [Text Block] Contract liabilities (Note 2) Contract with Customer, Liability, Current Materials and supplies Inventory, Raw Materials and Supplies, Gross Business Segments [Axis] Segments [Axis] Segments [Axis] Prepayments and other assets Increase (Decrease) in Prepaid Expense and Other Assets Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Local Phone Number Local Phone Number Capitalization Capitalization, Long-Term Debt and Equity [Abstract] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Other investing activities Payment for (Proceeds from) Other Investing Activity Subsequent Event Type [Axis] Subsequent Event Type [Axis] Water purchased Cost of Purchased Water Other Assets Regulatory and Other Assets [Abstract] -- None. No documentation exists for this element. -- ASSETS Assets [Abstract] Number of registrants filing combined report Number of Registrants Filing Combined Report Represents the number of registrants filing combined report during the period. Long-term debt Long-Term Debt, Excluding Current Maturities Underlying Security Market Price Change Underlying Security Market Price Change, Percent Components of Net Periodic Benefits Cost: Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Employee Benefit Plans Retirement Benefits [Text Block] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Supply costs Utilities Operating Expense, Products and Services Number of states in which entity operates Number of States in which Entity Operates Entity Address, Address Line One Entity Address, Address Line One Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by Used in Operating Activities Continuing Operations [Abstract] -- None. No documentation exists for this element. -- Accounts Receivable, allowance for doubtful accounts Accounts Receivable, Allowance for Credit Loss, Current Operating lease liabilities Operating Lease, Liability, Noncurrent Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Total other assets Regulatory and Other Assets This element represents aggregate carrying amount, at the balance sheet date, of noncurrent regulatory assets held by public utility entities and other noncurrent assets not separately disclosed in the balance sheet. CPUC-approved surcharges (cost-recovery activities) Surcharges (Cost-recovery Activities) [Member] Surcharges (Cost-recovery Activities) [Member] Fair Value as of Grant Date Award Grant Date Fair Value Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Net periodic benefits costs under accounting standards Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Schedule of regulatory assets, less regulatory liabilities in the consolidated balance sheets for continuing operations Schedule of Regulatory Assets Liabilities [Table Text Block] Tabular disclosure of regulatory assets, less regulatory liabilities, included in consolidated balance sheets for continuing operations. Stock-based compensation (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Regulated Operations [Abstract] Regulated Operations [Abstract] Document Quarterly Report Document Quarterly Report Contract assets (Note 2) Contract with Customer, Asset, before Allowance for Credit Loss, Noncurrent Number of plant facilities Number Of Plant Facility Number Of Plant Facility Deferred income taxes and investment tax credits Deferred Income Taxes and Tax Credits Long-term debt, fair value Long-Term Debt, Fair Value Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Number of contracts with 15 year contract Number of contracts Number of contracts with 15-year contract with the U.S. government. Interest cost Defined Benefit Plan, Interest Cost Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Restatement Determination Date: Restatement Determination Date [Axis] Issuances of Common Shares under stock-based compensation plans Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Non-PEO NEO Non-PEO NEO [Member] Other Regulatory assets Other Regulatory assets [Member] Other Regulatory assets Regulatory Asset [Axis] Regulatory Asset [Axis] Name Trading Arrangement, Individual Name Award Type [Domain] Award Type [Domain] Undistributed earnings for dilutive restricted stock units Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units Environmental costs recognized, capitalized Environmental Costs Recognized, Capitalized Equity Awards Adjustments Equity Awards Adjustments [Member] Other — net Other Noncash Income (Expense) Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Pension Plan's funded status and amounts recognized in balance sheets and the components of net pension cost and accrued post-retirement liability Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Other receivables Increase (Decrease) in Accounts and Other Receivables Compensation Amount Outstanding Recovery Compensation Amount Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Fair Value Estimate of Fair Value Measurement [Member] Revenue recognized Contract with Customer, Liability, Revenue Recognized Retirement Plan Type [Domain] Retirement Plan Type [Domain] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Regulatory liabilities not accruing carrying costs Regulatory Liabilities Not Accruing Carrying Costs Regulatory Liabilities Not Accruing Carrying Costs Name Awards Close in Time to MNPI Disclosures, Individual Name Other regulatory assets Other Regulatory Assets Net [Member] Represents the regulatory assets arising from other regulatory matters not specified in the taxonomy. Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Regulatory assets Regulatory Asset, Noncurrent Operating Revenues Revenues [Abstract] Schedule of reconciliation of total utility plant (a key figure for rate-making) to total consolidated assets Schedule Showing Reconciliation of Total Utility Plant to Total Consolidated Assets [Table Text Block] Tabular disclosure of reconciliation of total utility plant (a key figure for rate-making) to total consolidated assets. Effective Income Tax Rate [Table] Effective Income Tax Rate [Table] Income tax rate reconciliations and adjustments that are made in order to arrive at the effective income tax rate of the entity. Litigation Case [Axis] Litigation Case [Axis] Other property and investments Property Plant and Equipment and Investments Other Net This element represents capitalized assets classified as property, plant and equipment and other noncurrent investments not otherwise defined in the taxonomy. Segments [Domain] Segments [Domain] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Payments for commissions Payments for Commissions Basic: Earnings Per Share, Basic, Two Class Method [Abstract] Minimum Minimum [Member] Company Selected Measure Name Company Selected Measure Name Accrued liability for the estimated additional cost to complete the clean-up at the site Accrual for Environmental Loss Contingencies Fair Value Measurement [Domain] Fair Value Measurement [Domain] Water: Water: Water Service Utility Operations [Member] Represents the water service utility operations of the entity. Dividend equivalent rights on stock-based awards not paid in cash Dividends Equivalent Rights on Share Based Compensation Not Paid in Cash Net of Tax This element represents equity impact of dividend equivalent rights on stock-based awards which is not paid in cash during the reporting period. Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Accounts payable Accounts Payable, Current Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Total common shareholders earnings, diluted Net Income (Loss) Available to Common Stockholders, Diluted All Executive Categories All Executive Categories [Member] Common shares, no par value Common Stock, Value, Issued Contingencies Commitments and Contingencies Disclosure [Text Block] Groundwater production assessment Groundwater Production Assessment This element represents the aggregate expenses on groundwater production assessment. Weighted Average Number of Diluted Shares (in shares) Weighted Average Number of Diluted Shares (in shares) Weighted Average Number of Shares Outstanding, Diluted Commitments and Contingencies (Note 9) Commitments and Contingencies Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Entity Small Business Entity Small Business Payments of stock issuance costs Payments of Stock Issuance Costs Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Other operation Other Cost and Expense, Operating SERP Supplemental Employee Retirement Plan [Member] Document Transition Report Document Transition Report Derivative Instruments Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Depreciation on transportation equipment Public Utilities Property Plant and Equipment Depreciation on Transportation Equipment The amount of expense recognized in the current period that reflects the allocation of the cost of transportation equipment over the assets' useful lives. Reportable Legal Entities Reportable Legal Entities [Member] Underlying Securities Award Underlying Securities Amount Summary of significant accounting policies Accounting Policies [Line Items] -- None. No documentation exists for this element. -- Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Income Taxes Income Tax Disclosure [Text Block] Fully Diluted Earnings Per Share Earnings Per Share, Diluted [Abstract] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Dividend equivalent rights on stock-based awards not paid in cash Dividends Equivalent Rights on Share Based Compensation Net of Tax This element represents dividend equivalent rights on stock based awards, net of tax effect. Sale of stock, maximum consideration on transaction Sale of Stock, Maximum Consideration On Transaction Sale of Stock, Maximum Consideration On Transaction Document Type Document Type Earnings per Share/Capital Stock Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Loss Contingencies [Table] Loss Contingencies [Table] Power purchased for resale Utilities Operating Expense, Purchased Power Product and Service [Axis] Product and Service [Axis] Other accounts receivable, less allowance for doubtful accounts Accounts and Other Receivables, Net, Current Derivative Contract [Domain] Derivative Contract [Domain] Purchase power contract derivative at fair value (Note 5) Energy Marketing Contract Liabilities, Current Proceeds from Issuance of Common Stock Proceeds from Issuance of Common Stock Revenue from contract with customer, excluding assessed tax Revenue from Contract with Customer, Excluding Assessed Tax All Individuals All Individuals [Member] Less - accumulated depreciation Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Name Forgone Recovery, Individual Name Pension Costs and Other Postretirement Benefit Costs Pension Costs and Other Postretirement Benefit Costs [Member] Represents the regulatory assets arising from pensions and other post-retirement obligations. Total current assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Unbilled receivable Increase (Decrease) In Unbilled Contracts Receivables Increase (Decrease) In Unbilled Contracts Receivables Receivable from affiliate Other Receivables, Net, Current Regulatory Asset [Domain] Regulatory Asset [Domain] Regulatory assets/liabilities Increase (decrease) in regulatory assets and liabilities Increase (Decrease) in Regulatory Assets and Liabilities Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Other financing activities Payment, tax withholding, share-based payment arrangement Payment, Tax Withholding, Share-Based Payment Arrangement Wastewater Wastewater [Member] Wastewater [Member] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Common shareholders earnings, basic Net Income (Loss) Available to Common Stockholders, Basic Regulatory assets — current Regulatory Asset, Current Entity Information [Line Items] Entity Information [Line Items] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Current Liabilities Liabilities, Current [Abstract] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Number of customers Number of Customers Represents the number of customers who are served by the entity. Fully Diluted Earnings Per Common Share (in dollars per share) Diluted earnings per Common Share (in dollars per share) Earnings Per Share, Diluted Less: Impact from participating securities Participating Securities, Distributed and Undistributed Earnings (Loss), Basic Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Accounts receivable - customers, less allowance for doubtful accounts Accounts Receivable, after Allowance for Credit Loss, Current Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Title of 12(b) Security Title of 12(b) Security Property, Plant and Equipment, Other, Net [Abstract] Property, Plant and Equipment, Other, Net [Abstract] Sale of stock, number of shares issued in transaction (in shares) Sale of Stock, Number of Shares Issued in Transaction Earnings Per Share [Abstract] Earnings Per Share [Abstract] Stock-based compensation, net of taxes paid from shares withheld from employees related to net share settlements (Note 4) APIC, Share-Based Payment Arrangement, Option, Increase for Cost Recognition Other Investments and Securities, at Cost Other Investments and Securities, at Cost Consolidation Items [Domain] Consolidation Items [Domain] Total other income and expenses, net Nonoperating Income (Expense) Agreement term (in years) Sale of Stock, Agreement Term Sale of Stock, Agreement Term Unrealized (losses) gains on purchase power contracts Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss) Non-utility property, at cost Non Utilities Property Plant and Equipment, Gross This element represents the gross amount, at the balance sheet date, of non utility property assets used in the normal conduct of business and not intended for resale owned by a utility entity. Other Credits Liabilities, Other than Long-Term Debt, Noncurrent [Abstract] Contract liabilities Increase (Decrease) in Contract with Customer, Liability Regulated utility plant, at cost Utilities Property Plant and Equipment, Gross This element represents the gross amount, at the balance sheet date, of long-lived physical assets used in the normal conduct of business and not intended for resale owned by a utility entity used in the operations of the entity. Regulatory Liability [Domain] Regulatory Liability [Domain] Common Stock Shares Issued Not Disclosed Common Stock Shares Issued Not Disclosed Common Stock Shares Issued Not Disclosed Award Timing Disclosures [Line Items] Service cost Defined Benefit Plan, Service Cost Accrued employee expenses Employee-related Liabilities, Current Net Income Net income Net income Net Income (Loss) Attributable to Parent Intersegment Eliminations Intersegment Eliminations [Member] Expiration Date Trading Arrangement Expiration Date Other liabilities Increase (Decrease) in Other Operating Liabilities Other Other Accrued Liabilities, Current Payments to affiliate for corporate office administrative and general costs Related Party Transaction, Amounts of Transaction Electric Regulated Operating Revenue, Electric, Non-Nuclear Net property, plant and equipment Total net property, plant and equipment (4) Property, Plant and Equipment, Net Deduct: Deduction [Abstract] -- None. No documentation exists for this element. -- Details of reportable segment Segment Reporting Information [Line Items] Adoption Date Trading Arrangement Adoption Date Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Accounts receivable — customers Increase (Decrease) in Accounts Receivable Contract assets Contract with Customer, Asset, after Allowance for Credit Loss Schedule of Regulatory Assets and Liabilities [Line Items] Schedule of Regulatory Assets and Liabilities [Line Items] Schedule of Regulatory Assets and Liabilities [Line Items] Entity Current Reporting Status Entity Current Reporting Status Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Cash Flows From Financing Activities: Cash Provided by (Used in) Financing Activity, Continuing Operation [Abstract] Operating Income Operating Income (Loss) Capital stock Capital Unit [Line Items] Consolidated Entities [Domain] Consolidated Entities [Domain] Retained earnings Retained Earnings (Accumulated Deficit) Notes payable to banks Notes Payable to Bank, Noncurrent Consolidated Balance Sheets(Parenthetical) Statement of Financial Position [Abstract] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Executive Category: Executive Category [Axis] Current Fiscal Year End Date Current Fiscal Year End Date Subsequent Event Type [Domain] Subsequent Event Type [Domain] Receivable/payable from/to affiliate Increase (Decrease) in Related Party Receivable Payable, Current The increase (decrease) during the reporting period of related party receivables/payables which are due within one year or one business cycle. Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Environmental loss contingencies paid by third party Environmental Loss Contingencies Paid by Third Party Environmental Loss Contingencies Paid by Third Party Retirement Plan Type [Axis] Retirement Plan Type [Axis] Other, net Other Nonoperating Income (Expense) Statement [Table] Statement [Table] Net changes in notes payable to banks Proceeds from (Repayments of) Notes Payable Regulatory matters: Regulatory Assets and Liabilities [Line Items] -- None. No documentation exists for this element. -- Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Revenue Benchmark Revenue Benchmark [Member] Tariff-based revenues Tariff-based Revenues [Member] Tariff-based Revenues [Member] Power purchased for pumping Power Purchased for Pumping This element represents Power purchased for pumping expenses. Contract liabilities Contract with Customer, Liability Proceeds from the issuance of long-term debt, net of issuance costs Proceeds from Debt, Net of Issuance Costs All Adjustments to Compensation All Adjustments to Compensation [Member] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Amendment Flag Amendment Flag Other Postretirement Benefits Other Postretirement Benefits Plan [Member] Receipt of advances for and contributions in aid of construction Proceeds from Advance for Construction, Investing Activity Termination Date Trading Arrangement Termination Date Net cash provided (used) Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Contract assets Increase (Decrease) in Contract with Customer, Asset Receivable from the U.S. government (Note 2) Account Receivable from US Government, Net,Noncurrent Account Receivable from US Government, Net,Noncurrent Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Measure: Measure [Axis] Other assets Assets Other than Property Plant and Equipment, Net Sum of the carrying amounts as of the balance sheet date of all assets except utility plant that are recognized. Receivables from the U.S. government Increase (Decrease) Receivable from Government The net change during the reporting period in amount receivable from the government. Receivable from the U.S. government Government Contract Receivable Weighted Average Number of Common Shares Outstanding (in shares) Weighted average Common Shares outstanding, basic (in shares) Weighted Average Number of Shares Outstanding, Basic ASUS construction Cost of Product and Service Sold Related Party Transaction [Domain] Related Party Transaction [Domain] Segment Reporting [Abstract] Segment Reporting [Abstract] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Common Stock Including Additional Paid in Capital Common Stock Including Additional Paid in Capital [Member] Other Income and Expenses Nonoperating Income (Expense) [Abstract] Entity Tax Identification Number Entity Tax Identification Number Supply cost balancing accounts Supply Cost Balancing Accounts This element represents the supply cost balancing accounts maintained for under-collections and over-collections of revenues designed to recover such costs. Contracted services Regulated Operating Revenue, Other Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Consolidated Entities [Axis] Consolidated Entities [Axis] Common Stock, Par Value (in usd per share) Common Stock, Par or Stated Value Per Share Beginning Balance (in shares) Ending Balances (in shares) Common Stock, Shares, Issued Income taxes receivable from Parent Income Taxes Receivable, Current Regulatory liability Regulatory Liability Contract assets (Note 2) Contract with Customer, Asset, before Allowance for Credit Loss, Current Public Utilities, Regulatory Proceeding [Axis] Public Utilities, Regulatory Proceeding [Axis] Regulatory asset Regulatory Asset Dividends paid Dividends paid Payments of Dividends Interest expense Interest Expense, Nonoperating Trading Arrangement: Trading Arrangement [Axis] Total Shareholder Return Amount Total Shareholder Return Amount Loss Contingencies [Line Items] Loss Contingencies [Line Items] Insider Trading Arrangements [Line Items] Security Exchange Name Security Exchange Name Alternative revenue programs, net Alternative Revenue Programs, Net Alternative Revenue Programs, Net Property installed by developers and conveyed Contribution of Property Accrued payables for investment in utility plant Capital Expenditures Incurred but Not yet Paid Mutual Funds Mutual Funds [Member] Mutual Funds [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Operating Expenses Operating Expenses [Abstract] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Fair Value by Asset Class [Domain] Asset Class [Domain] Accrued pension and other postretirement benefits Liability, Defined Benefit Plan, Noncurrent Maintenance Utilities Operating Expense, Maintenance and Operations Issuance of Common Shares from an at-the-market program, net of issuance costs Stock Issued During Period, Value, New Issues Accrued other taxes Franchise and Assessment Fees Taxes Represents franchise and assessment fees taxes. Statement [Line Items] Statement [Line Items] Consolidation Items [Axis] Consolidation Items [Axis] Unamortized debt issuance expense Unamortized Debt Issuance Expense Schedule of Capital Units [Table] Equity, Capital Unit or Share [Table] Flowed-through deferred income taxes, net Flow Through Taxes Net [Member] Represents the regulatory assets arising from flow-through taxes, net. ASUS construction Cost of Construction Cost of Construction Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and Cash Equivalent Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member]