Other, net
Nontrade Receivables, Current
Dividends paid on common stock (in dollars per share)
Common Stock, Dividends, Per Share, Cash Paid
Operating expenses:
Utilities Operating Expense [Abstract]
Summary of Significant Accounting Policies
Significant Accounting Policies [Text Block]
Estimated cash contributions in the current fiscal year
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year
Statistical Measurement [Domain]
Statistical Measurement [Domain]
Total capitalization
Capitalization, Long-Term Debt and Equity
Expected return on plan assets
Defined Benefit Plan, Expected Return (Loss) on Plan Assets
Other accrued benefits
Other Accrued Benefits [Member]
Represents the other accrued benefits not otherwise specified in the taxonomy.
Restricted cash
Restricted cash
Restricted Cash, Current
Award Timing Predetermined
Award Timing Predetermined [Flag]
Entity File Number
Entity File Number
Additional Paid-in Capital
Additional Paid-in Capital [Member]
Tabular List, Table
Tabular List [Table Text Block]
Recently Adopted Accounting Pronouncements and New Accounting Standards Not Yet Adopted
New Accounting Pronouncements, Policy [Policy Text Block]
Accounts payable
Increase (Decrease) in Accounts Payable
Secured Overnight Financing Rate (SOFR)
Secured Overnight Financing Rate (SOFR) [Member]
Trading Arrangements, by Individual
Trading Arrangements, by Individual [Table]
Measurement Basis [Axis]
Measurement Basis [Axis]
Basic (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]
Regulatory Assets and Liabilities
Public Utilities Disclosure [Text Block]
Net actuarial loss
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member]
Expected future payment
Business Combination, Expected Future Payment
Business Combination, Expected Future Payment
Schedule of Stock by Class [Table]
Stock, Class of Stock [Table]
Other comprehensive income, net of tax
Other comprehensive income, net of tax
Other Comprehensive Income (Loss), Net of Tax
Supply Commitment
Supply Commitment [Member]
Short-term borrowings
Short-Term Debt
Schedule of Cash and Cash Equivalents
Schedule of Cash and Cash Equivalents [Table Text Block]
Other components of net periodic benefit credit
Other components of net periodic benefit credit
Defined Benefit Plan, Other Cost (Credit)
Adjustment to Compensation, Amount
Adjustment to Compensation Amount
Pension Plan
Pension Plan [Member]
Amortization of prior service cost
Defined Benefit Plan, Amortization and Deferral of Gains (Losses)
Defined Benefit Plan, Amortization and Deferral of Gains (Losses)
Depreciation and amortization
Utilities Operating Expense, Depreciation and Amortization
Employee Stock Option
Share-Based Payment Arrangement, Option [Member]
Award Timing MNPI Disclosure
Award Timing MNPI Disclosure [Text Block]
Conservation Expense Balancing Account
Conservation Program Liability [Member]
Discloses the amount of regulatory liability arising from the difference between conservation program liability, according to US GAAP, and the amount of conservation program liability considered for rate-making purposes, according the actions of the regulator.
Dividends paid on common stock
Dividends, Common Stock, Cash
Other comprehensive income:
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Operating revenue
Total operating revenue
Regulated Operating Revenue, Water
Insider Trading Policies and Procedures [Line Items]
Recorded compensation costs for the RSAs and RSUs
Share-Based Payment Arrangement, Expense
3M Company
3M Company [Member]
3M Company
Common stock, shares authorized (in shares)
Common Stock, Shares Authorized
Issuance of common stock (in shares)
Stock Issued During Period, Shares, New Issues
Business
Business [Member]
Business [Member]
Current assets:
Assets, Current [Abstract]
TOTAL CAPITALIZATION AND LIABILITIES
Liabilities and Equity
Other current liabilities
Increase (Decrease) in Other Current Liabilities
Noncontrolling Interest [Line Items]
Noncontrolling Interest [Line Items]
Accumulated Defined Benefit Plans Adjustment Attributable to Parent
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
CAPITALIZATION AND LIABILITIES
Liabilities and Equity [Abstract]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income and expenses:
Other Nonoperating Income (Expense) [Abstract]
Cover [Abstract]
Cover [Abstract]
Portion at fair value measurement
Portion at Fair Value Measurement [Member]
Maximum
Maximum [Member]
Net loss attributable to noncontrolling interest
Net Income (Loss) Attributable to Noncontrolling Interest
Accounting Policies [Abstract]
Accounting Policies [Abstract]
Nexus Water Group
Nexus Water Group [Member]
Nexus Water Group
RSAs
Restricted Stock [Member]
Non-PEO NEO Average Total Compensation Amount
Non-PEO NEO Average Total Compensation Amount
Debt Instrument [Line Items]
Debt Instrument [Line Items]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table]
Schedule of Restricted Stock and Restricted Stock Unit Activity
Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]
Adjustment to Non-PEO NEO Compensation Footnote
Adjustment to Non-PEO NEO Compensation Footnote [Text Block]
Pay vs Performance Disclosure [Line Items]
Long-term debt, including current maturities, net
Debt, Long-Term and Short-Term, Combined Amount
Industrial
Industrial [Member]
Industrial [Member]
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]
Entity Shell Company
Entity Shell Company
Common Stock Shares Issued Not Disclosed
Common Stock Shares Issued Not Disclosed
Common Stock Shares Issued Not Disclosed
Other long-term liabilities
Other Liabilities, Noncurrent
Schedule of Long-term Debt Instruments [Table]
Schedule of Long-Term Debt Instruments [Table]
Accrued other taxes
Accrual for Taxes Other than Income Taxes, Current
Statement of Cash Flows [Abstract]
Statement of Cash Flows [Abstract]
Current maturities of long-term debt, net
Long-Term Debt, Current Maturities
Company Selected Measure Amount
Company Selected Measure Amount
Employer cash contributions
Defined Benefit Plan, Plan Assets, Contributions by Employer
Comprehensive loss attributable to noncontrolling interest
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest
Award Timing MNPI Considered
Award Timing MNPI Considered [Flag]
Comprehensive income attributable to California Water Service Group
Comprehensive Income (Loss), Net of Tax, Attributable to Parent
Reclassification out of Accumulated Other Comprehensive Income [Table]
Reclassification out of Accumulated Other Comprehensive Income [Table]
Name
Measure Name
Payment for purchase of noncontrolling interest
Payments to Noncontrolling Interests
Refunds of advances for construction
Refunds Of Advances For Construction
Refunds Of Advances For Construction
Class of Stock [Line Items]
Class of Stock [Line Items]
Deferred income taxes
Deferred Income Tax Liabilities, Net
Document Fiscal Period Focus
Document Fiscal Period Focus
Award Timing Method
Award Timing Method [Text Block]
Award Type [Axis]
Award Type [Axis]
Parent Company
Parent Company [Member]
Legal Entity [Axis]
Legal Entity [Axis]
TOTAL ASSETS
Assets
Future tax benefits due to customers
Deferred Income Tax Charge [Member]
Investment, Name [Domain]
Investment, Name [Domain]
Trading Symbol
Trading Symbol
Vested (in dollars per share)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value
Regulatory Liability [Axis]
Regulatory Liability [Axis]
Maximum consideration on transaction
Sale of Stock, Maximum Consideration On Transaction
Sale of Stock, Maximum Consideration On Transaction
Other accrued liabilities
Accrued Liabilities and Other Liabilities
Entity Address, City or Town
Entity Address, City or Town
Asset retirement obligations, net
Asset Retirement Obligation Costs [Member]
Operating activities:
Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract]
Utility plant
Public Utilities, Property, Plant and Equipment, Plant in Service
MWRAM long-term regulatory asset
Monterey-Style Water Revenue Adjustment Mechanism (MWRAM) [Member]
Monterey-Style Water Revenue Adjustment Mechanism (MWRAM)
Property-related temporary differences (tax benefits flowed through to customers)
Property-Related Temporary Differences (Tax Benefits Flowed Through To Customers) [Member]
Property-Related Temporary Differences (Tax Benefits Flowed Through To Customers) [Member]
Non-PEO NEO Average Compensation Actually Paid Amount
Non-PEO NEO Average Compensation Actually Paid Amount
RSUs
Restricted Stock Units (RSUs) [Member]
Allowance for Credit Losses
Credit Loss, Financial Instrument [Policy Text Block]
Compensation Actually Paid vs. Other Measure
Compensation Actually Paid vs. Other Measure [Text Block]
Multiple residential
Multiple Residential [Member]
Multiple Residential
Entity Emerging Growth Company
Entity Emerging Growth Company
Materials and supplies
Public Utilities, Inventory
Entity Common Stock, Shares Outstanding
Entity Common Stock, Shares Outstanding
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]
Level 2
Fair Value, Inputs, Level 2 [Member]
Insider Trading Policies and Procedures Not Adopted
Insider Trading Policies and Procedures Not Adopted [Text Block]
Business Combination [Domain]
Business Combination [Domain]
Common stock, shares outstanding (in shares)
Balance at beginning of period (in shares)
Balance at end of period (in shares)
Common Stock, Shares, Outstanding
Performance-Based Restricted Stock Unit Awards (RSUs)
Performance-Based Restricted Stock Unit Awards (RSUs) [Member]
Performance-Based Restricted Stock Unit Awards (RSUs) [Member]
Provision for credit loss expense
Accounts Receivable, Credit Loss Expense (Reversal)
Schedule of Components of Income Tax Expense (Benefit)
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]
2026
Period One [Member]
Period One
Plan Name [Axis]
Plan Name [Axis]
Health Cost Balancing Account
Health Care Balancing Account [Member]
Rate action of a regulator resulting in capitalization or accrual of costs for the health care balancing account.
PEO
PEO [Member]
Number of claims
Loss Contingency, Pending Claims, Number
Disaggregation of Revenue
Disaggregation of Revenue [Table Text Block]
Tank coating
Tank Coating [Member]
Rate action of a regulator resulting in capitalization or accrual of costs for the tank coating.
Changes in operating 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]
Total operating expenses
Utilities Operating Expense
Retained Earnings
Retained Earnings [Member]
Number of RSA Shares
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Entity Address, Postal Zip Code
Entity Address, Postal Zip Code
Restatement Determination Date
Restatement Determination Date
Share-based Payment Arrangement [Abstract]
Share-Based Payment Arrangement [Abstract]
Cash, cash equivalents, and restricted cash at beginning of period
Cash, cash equivalents, and restricted cash at end of period
Total cash, cash equivalents, and restricted cash
Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation
Income Statement [Abstract]
Income Statement [Abstract]
Income tax expense
Tax benefit
Income Tax Expense (Benefit)
Interest rate
Debt Instrument, Basis Spread on Variable Rate
Pension Adjustments Service Cost
Pension Adjustments Service Cost [Member]
Product and Service [Domain]
Product and Service [Domain]
Fair Value Hierarchy and NAV [Axis]
Fair Value Hierarchy and NAV [Axis]
DuPont
DuPont [Member]
DuPont
Net income
Net income
Net income
Net income
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest
Purchase obligation
Recorded Unconditional Purchase Obligation
Restatement does not require Recovery
Restatement Does Not Require Recovery [Text Block]
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other current assets
Increase (Decrease) in Other Current Assets
Compensation Actually Paid vs. Company Selected Measure
Compensation Actually Paid vs. Company Selected Measure [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]
Other components of net periodic benefit cost
Other Components Of Net Periodic Benefit Cost [Member]
Other Components Of Net Periodic Benefit Cost
Equity Incentive Plan 2024
Equity Incentive Plan 2024 [Member]
Equity Incentive Plan 2024
Beginning balance (in shares)
Ending balance (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]
Investing activities:
Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract]
Administrative and general
General and Administrative Expense
Pay vs Performance Disclosure
Pay vs Performance Disclosure [Table]
Net cash provided by operating activities
Cash Provided by (Used in) Operating Activity, Including Discontinued Operation
Repayment of short-term borrowings
Repayments of Short-Term Debt
Utility plant expenditures
Payments to Acquire Water and Waste Water Systems
Debt instrument, term
Debt Instrument, Term
Subsequent Event
Subsequent Event [Member]
Goodwill
Goodwill
Equity Valuation Assumption Difference, Footnote
Equity Valuation Assumption Difference, Footnote [Text Block]
PEO Total Compensation Amount
PEO Total Compensation Amount
Payments for other commitments
Payments For Other Commitments
Payments For Other Commitments
Equity Components [Axis]
Equity Components [Axis]
Non-Rule 10b5-1 Arrangement Adopted
Non-Rule 10b5-1 Arrangement Adopted [Flag]
Operations:
Operating Costs and Expenses [Abstract]
Regulatory Assets and Liabilities [Line Items]
Regulatory Assets and Liabilities [Line Items]
Supplemental disclosures of cash flow information:
Supplemental Cash Flow Information [Abstract]
Contract operating and maintenance revenue
Contract Operating and Maintenance Revenue [Member]
Represents the revenue and expense associated with operating and maintenance services provided for water and wastewater systems owned by private companies and municipalities.
Other Performance Measure, Amount
Other Performance Measure, Amount
Regulatory liabilities
Total Regulatory Liabilities
Regulatory Liability, Noncurrent
Entity Address, State or Province
Entity Address, State or Province
Pension
Liability, Other Postretirement Defined Benefit Plan, Noncurrent
Total current liabilities
Liabilities, Current
Increase in regulated revenue
Increase (Decrease) In Regulated Operating Revenue Expected In Future Periods
Increase (Decrease) In Regulated Operating Revenue Expected In Future Periods
Allowance for borrowed funds used during construction
Interest Costs Capitalized Adjustment
Individual:
Individual [Axis]
Dividends paid
Payments of Ordinary Dividends, Common Stock
Additional paid-in capital
Additional Paid in Capital, Common Stock
Entity [Domain]
Entity [Domain]
Net cash used in investing activities
Cash Provided by (Used in) Investing Activity, Including Discontinued Operation
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]
Taxes, prepaid expenses, and other assets
Taxes, Prepaid Expenses and Other Assets, Current
This element represents Taxes, prepaid expenses and other assets.
Cash paid for interest (net of amounts capitalized)
Interest Paid, Excluding Capitalized Interest, Operating Activity
Document Fiscal Year Focus
Document Fiscal Year Focus
Basis of Presentation
Basis of Accounting, Policy [Policy Text Block]
Forgone Recovery, Explanation of Impracticability
Forgone Recovery, Explanation of Impracticability [Text Block]
Noncontrolling interest
Subsidiary, Ownership Percentage, Noncontrolling Owner
Repayment of long-term debt
Repayments of Long-Term Debt
Effective tax rate estimate
Effective Income Tax Rate Reconciliation, Percent
Entity Interactive Data Current
Entity Interactive Data Current
Cost
Reported Value Measurement [Member]
Plan Name [Domain]
Plan Name [Domain]
Risk premium (as a percent)
Fair Value Inputs Risk Premium
Represents the risk premium rate as an input to measure fair value.
Period for recognition
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition
Equity [Abstract]
Equity [Abstract]
Cost of removal
Removal Obligation [Member]
Removal Obligation
Segment Information
Segment Reporting Disclosure [Text Block]
Sale of stock, agreement term
Sale of Stock, Agreement Term
Sale of Stock, Agreement Term
Fair Value of Financial Assets and Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Disaggregation of Revenue [Table]
Disaggregation of Revenue [Table]
Cliff vesting period
Share-Based Compensation Arrangement by Share-Based Payment Award, Cliff Vesting Period
Share-Based Compensation Arrangement by Share-Based Payment Award, Cliff Vesting Period
Interim Rates Memorandum Account (IRMA) long-term accounts receivable
Interim Rates Long Term Accounts Receivable [Member]
Represents the interim rates long term accounts receivable.
Options vested on anniversary date
Share Based Compensation Arrangement by Share-based Payment Award, Award Vesting Rate
The rate of vesting of awards when they are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date.
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BVRT Utility Holding Company LLC
BVRT Utility Holding Company LLC [Member]
BVRT Utility Holding Company LLC
Ownership [Domain]
Ownership [Domain]
Schedule of components of net periodic benefit costs for the pension plans and other postretirement benefits
Schedule of Net Benefit Costs [Table Text Block]
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 revenues that are included in rate-setting to the balance sheet.
Compensation Actually Paid vs. Total Shareholder Return
Compensation Actually Paid vs. Total Shareholder Return [Text Block]
Accumulated Other Comprehensive Loss
Comprehensive Income (Loss) Note [Text Block]
Fair Value, Recurring and Nonrecurring [Table]
Fair Value, Recurring and Nonrecurring [Table]
Repurchase of common stock
Stock Repurchased During Period, Value
Schedule of Accumulated Other Comprehensive Income (Loss)
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]
Depreciation and amortization
Depreciation, Depletion and Amortization
Other
Other Assets, Noncurrent
Accrued interest
Interest Payable, Current
Entity Central Index Key
Entity Central Index Key
PEO Name
PEO Name
Non-regulated revenue from contracts with customers
Non-Regulated Services [Member]
Non-Regulated Services [Member]
Income tax expense decrease
Effective Income Tax Rate Reconciliation, Increase (Decrease), Amount
Effective Income Tax Rate Reconciliation, Increase (Decrease), Amount
Issuance of common stock
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]
Outstanding Aggregate Erroneous Compensation Amount
Outstanding Aggregate Erroneous Compensation Amount
Schedule of Changes in Total Common Stockholders' Equity
Schedule of Stockholders Equity [Table Text Block]
Revolving Credit Facility
Revolving Credit Facility [Member]
Non-regulated revenue
Total non-regulated revenue
Unregulated Operating Revenue
Schedule of Defined Benefit Plans Disclosures [Table]
Defined Benefit Plan [Table]
Arrangement Duration
Trading Arrangement Duration
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]
Unrecognized compensation cost
Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount
Other
Payment for (Proceeds from) Other Investing Activity
Subsequent Event Type [Axis]
Subsequent Event Type [Axis]
Stock-Based Compensation
Share-Based Payment Arrangement [Text Block]
ASSETS
Assets [Abstract]
Credit Facility [Axis]
Credit Facility [Axis]
Underlying Security Market Price Change
Underlying Security Market Price Change, Percent
Other Commitments [Axis]
Other Commitments [Axis]
Components of the pension plans and other postretirement benefits
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Fair Value of Financial Assets and Liabilities
Fair Value Disclosures [Text Block]
Pension Plan and Other Postretirement Benefits
Retirement Benefits [Text Block]
Credit Facility [Domain]
Credit Facility [Domain]
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]
Water production costs
Utilities Operating Expense, Products and Services
Short-term borrowings
Proceeds from Short-Term Debt
Entity Address, Address Line One
Entity Address, Address Line One
Market-Based Restricted Stock Unit Awards (RSUs)
Market-Based Restricted Stock Unit Awards (RSUs) [Member]
Market-Based Restricted Stock Unit Awards (RSUs)
Allowance for equity funds used during construction
Allowance for equity funds used during construction
Public Utilities, Allowance for Funds Used During Construction, Additions
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent [Member]
Investment, Name [Axis]
Investment, Name [Axis]
BVRT Water Company
BVRT Water Company [Member]
BVRT Water Company
Recovery Period
Regulatory Asset, Amortization Period
Ownership [Axis]
Ownership [Axis]
Performance criteria adjustment (in dollars per share)
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Performance Criteria Adjustment, Weighted Average Grant Date Fair Value
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Performance Criteria Adjustment, Weighted Average Grant Date Fair Value
Other operations
Utilities Operating Expense, Other
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 benefit cost (credit)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Granted (in shares)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period
Title of Individual [Domain]
Title and Position [Domain]
Regulated Operations [Abstract]
Regulated Operations [Abstract]
Document Quarterly Report
Document Quarterly Report
Changed Peer Group, Footnote
Changed Peer Group, Footnote [Text Block]
Counterparty Name [Domain]
Counterparty Name [Domain]
Number of operating segments
Number of Operating Segments
Adjustment To PEO Compensation, Footnote
Adjustment To PEO Compensation, Footnote [Text Block]
Interest cost
Defined Benefit Plan, Interest Cost
Granted (in dollars per share)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value
Title
Trading Arrangement, Individual Title
Peer Group Total Shareholder Return Amount
Peer Group Total Shareholder Return Amount
Restatement Determination Date:
Restatement Determination Date [Axis]
Initial payment
Payments to Acquire Businesses, Gross
Non-PEO NEO
Non-PEO NEO [Member]
Accumulated Other Comprehensive Income (Loss) [Table]
Accumulated Other Comprehensive Income (Loss) [Table]
Residential
Residential [Member]
Residential [Member]
Advances and contributions in aid of construction
Proceeds From Contribution In Aid Of Construction, Financing Activities
Proceeds From Contribution In Aid Of Construction, Financing Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from AOCL
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax
Regulatory Asset [Axis]
Regulatory Asset [Axis]
Name
Trading Arrangement, Individual Name
Award Type [Domain]
Award Type [Domain]
Noncontrolling interest
Equity, Attributable to Noncontrolling Interest
Equity Awards Adjustments
Equity Awards Adjustments [Member]
Pension Benefits Adjustments, Footnote
Pension Benefits Adjustments, Footnote [Text Block]
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Line Items]
Pension Plan and Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Compensation Amount
Outstanding Recovery Compensation Amount
Tyco
Tyco [Member]
Tyco
Statement of Comprehensive Income [Abstract]
Recovery of Erroneously Awarded Compensation Disclosure [Line Items]
Regulated Operation Revenue Period [Axis]
Regulated Operation Revenue Period [Axis]
Regulated Operation Revenue Period
Fair Value
Estimate of Fair Value Measurement [Member]
Amortization of defined benefit pension plans, net of taxes
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax
Retirement Plan Type [Domain]
Retirement Plan Type [Domain]
Schedule of Allowance for Credit Losses
Accounts Receivable, Allowance for Credit Loss [Table Text Block]
MNPI Disclosure Timed for Compensation Value
MNPI Disclosure Timed for Compensation Value [Flag]
Name
Awards Close in Time to MNPI Disclosures, Individual Name
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance (in dollars per share)
Ending balance (in dollars per share)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Aggregate Erroneous Compensation Not Yet Determined
Aggregate Erroneous Compensation Not Yet Determined [Text Block]
Regulatory assets
Total Regulatory Assets
Regulatory Asset, Noncurrent
Long-term debt, net
Long-Term Debt and Lease Obligation
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss), Net of Tax
Other non-regulated revenue
Other Non-Regulated Service [Member]
Other Non-Regulated Service [Member]
Public authorities
Public Authorities [Member]
Public Authorities [Member]
Accrued and unbilled revenue, net
Receivables, Long-Term Contracts or Programs
General District Balancing Account receivable
General District Balancing Account Receivable [Member]
General District Balancing Account Receivable
Aggregate Pension Adjustments Service Cost
Aggregate Pension Adjustments Service Cost [Member]
Fair Value Hierarchy and NAV [Domain]
Fair Value Hierarchy and NAV [Domain]
Payments for commissions
Payments for Commissions
Minimum
Minimum [Member]
Earnings per Share
Earnings Per Share, Policy [Policy Text Block]
Revenue from contracts with customers and Regulatory balancing account revenue
Revenue Recognition for Alternative Revenue Programs, Policy [Policy Text Block]
Company Selected Measure Name
Company Selected Measure Name
Advances for construction
Contract with Customer, Refund Liability, Noncurrent
Fair Value Measurement [Domain]
Fair Value Measurement [Domain]
Non-Regulated Revenue
Revenue [Policy Text Block]
Investment in business with noncontrolling interest
Noncontrolling Interest, Increase From Investment In Business
Noncontrolling Interest, Increase From Investment In Business
Other changes in noncurrent assets and liabilities
Increase (Decrease) in Other Noncurrent Assets and Liabilities, Net
Short-term and Long-term Borrowings
Debt Disclosure [Text Block]
Aggregate Available
Trading Arrangement, Securities Aggregate Available Amount
Accounts payable
Accounts Payable, Current
Stock Appreciation Rights (SARs)
Stock Appreciation Rights (SARs) [Member]
All Executive Categories
All Executive Categories [Member]
Common stock, $0.01 par value; 136,000 shares authorized, 59,853 and 59,638 outstanding on March 31, 2026 and December 31, 2025, respectively
Common Stock, Value, Issued
Commitments and Contingencies
Commitments and Contingencies Disclosure [Text Block]
Title of Individual [Axis]
Title and Position [Axis]
Other assets:
Other Assets, Noncurrent [Abstract]
Diluted (in shares)
Weighted Average Number of Shares Outstanding, Diluted
Pension Balancing Account [Member]
Pension Balancing Account [Member]
Pension Balancing Account [Member]
Maximum collection period in which deferred net WRAM and MCBA revenues and associated costs will be recognized
Maximum Collection Period in which Deferred Net WRAM and MCBA Revenues and Associated Costs will be Recognized
Represents the maximum collection period in which deferred net WRAM and MCBA revenues and associated costs will be recognized.
Commitments and contingencies (Note 9)
Commitments and Contingencies
Non-GAAP Measure Description
Non-GAAP Measure Description [Text Block]
Incremental Cost Balancing Accounts (ICBA)
Incremental Cost Balancing Account (ICBA) [Member]
Incremental Cost Balancing Account (ICBA)
Business Combination [Axis]
Business Combination [Axis]
Comprehensive income
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest
Income tax expense
Utilities Operating Expense (Income) Tax Expense (Benefit)
The sum of the current income tax expense or benefit and the deferred income tax expense or benefit included in operating expense of a utility.
Entity Small Business
Entity Small Business
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Abstract]
Noncontrolling Interest
Noncontrolling Interest [Member]
Document Transition Report
Document Transition Report
Net interest expense
Interest Costs Incurred
Ownership percentage
Equity Method Investment, Ownership Percentage
Noncontrolling Interest [Table]
Noncontrolling Interest [Table]
Underlying Securities
Award Underlying Securities Amount
Income tax expense on other income and expenses
Income taxes on other income and expenses
Utilities Nonregulated Expense, Income Tax Expense (Benefit)
The sum of the current income tax expense or benefit and the deferred income tax expense or benefit included in other income and expenses of a utility.
Equity Component [Domain]
Equity Component [Domain]
Non-regulated expenses
Other Nonoperating Expense
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]
Beginning balance
Total ending allowance balance
Accounts Receivable, Allowance for Credit Loss
Awards Close in Time to MNPI Disclosures, Table
Awards Close in Time to MNPI Disclosures [Table Text Block]
Receivables:
Receivables, Net, Current [Abstract]
Total equity
Balance at beginning of period
Balance at end of period
Equity, Including Portion Attributable to Noncontrolling Interest
Document Type
Document Type
Level 3
Fair Value, Inputs, Level 3 [Member]
Name
Outstanding Recovery, Individual Name
Product and Service [Axis]
Product and Service [Axis]
Issuance of common stock
Proceeds from Issuance of Common Stock
Revenue from contracts with customers
Revenue from Contract with Customer, Excluding Assessed Tax
All Individuals
All Individuals [Member]
Less accumulated depreciation and amortization
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Abstract]
Receivables and accrued and unbilled revenue
Increase (Decrease) in Receivables
Name
Forgone Recovery, Individual Name
Property and other taxes
Utilities Operating Expense, Taxes
Performance period
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period
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]
Prior service cost
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Including Portion Attributable to Noncontrolling Interest [Member]
Reclassification out of Accumulated Other Comprehensive Income
Reclassification out of Accumulated Other Comprehensive Income [Member]
Regulatory Asset [Domain]
Regulatory Asset [Domain]
Aggregate Erroneous Compensation Amount
Aggregate Erroneous Compensation Amount
Peer Group Issuers, Footnote
Peer Group Issuers, Footnote [Text Block]
Other regulatory assets
Other Regulatory Assets [Member]
Represents information pertaining to other regulatory assets.
Short-term regulatory accounts
Short-term portion of the regulatory assets
Regulatory Asset, Current
Erroneous Compensation Analysis
Erroneous Compensation Analysis [Text Block]
Current liabilities:
Liabilities, Current [Abstract]
Lessee, Lease, Description [Line Items]
Lessee, Lease, Description [Line Items]
BASF
BASF [Member]
BASF
Regulated Operation Revenue Period [Domain]
Regulated Operation Revenue Period [Domain]
Regulated Operation Revenue Period [Domain]
Customer Assistance Program and Rate Support Fund accounts receivable
Customer Assistance Program And Rate Support Fund Accounts Receivable [Member]
Customer Assistance Program And Rate Support Fund Accounts Receivable
Rule 10b5-1 Arrangement Terminated
Rule 10b5-1 Arrangement Terminated [Flag]
Level 1
Fair Value, Inputs, Level 1 [Member]
Outstanding borrowings
Long-Term Line of Credit
Diluted (in dollars per share)
Earnings Per Share, Diluted
Erroneously Awarded Compensation Recovery
Erroneously Awarded Compensation Recovery [Table]
Customers, net
Accounts Receivable, after Allowance for Credit Loss, Current
Reclassification out of Accumulated Other Comprehensive Income [Axis]
Reclassification out of Accumulated Other Comprehensive Income [Axis]
Title of 12(b) Security
Title of 12(b) Security
Lessee, Lease, Description [Table]
Lessee, Lease, Description [Table]
Supplemental disclosure of investing and financing non-cash activities:
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Other
Service, Other [Member]
Sale of stock, number of shares issued in transaction (in shares)
Sale of Stock, Number of Shares Issued in Transaction
2028
Period Three [Member]
Period Three
Officer
Officer [Member]
Earnings per share:
Earnings Per Share [Abstract]
Incremental expansion of borrowing capacity
Line Of Credit Facility, Incremental Expansion Of Borrowing Capacity
Line Of Credit Facility, Incremental Expansion Of Borrowing Capacity
Recoverable property losses
Recoverable Property Losses [Member]
Recoverable Property Losses [Member]
Recognized net actuarial loss (gain)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)
Regulatory Liability [Domain]
Regulatory Liability [Domain]
Net WRAM and Modified Cost Balancing Account (MCBA) long-term accounts receivable
Accounts Receivable Net W R A M And M C B A Accounts Receivable [Member]
Represents the net accounts receivable under Water Revenue Adjustment Mechanism (WRAM) and the Modified Cost Balancing Account (MCBA).
Utility plant:
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Award Timing Disclosures [Line Items]
Service cost
Defined Benefit Plan, Service Cost
Interest expense:
Interest Costs Incurred [Abstract]
Recoveries
Accounts Receivable, Allowance for Credit Loss, Recovery
2027
Period Two [Member]
Period Two
Equity
Equity [Text Block]
Distribution to noncontrolling interest
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders
Net income attributable to California Water Service Group
Total reclassification for the period, net of tax
Net Income (Loss) Attributable to Parent
Total other assets
Total Other Assets
Total noncurrent portion of other assets.
Subsequent Event [Table]
Subsequent Event [Table]
Expiration Date
Trading Arrangement Expiration Date
Net utility plant
Public Utilities, Property, Plant and Equipment, Net
Other Commitments [Domain]
Other Commitments [Domain]
Vesting period
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Regulatory balancing account revenue
Revenue Not from Contract with Customer
Repurchase of common stock
Payments for Repurchase of Common Stock
Adoption Date
Trading Arrangement Adoption Date
Base Rate
Base Rate [Member]
Compensation Actually Paid vs. Net Income
Compensation Actually Paid vs. Net Income [Text Block]
Entity Current Reporting Status
Entity Current Reporting Status
Awards Close in Time to MNPI Disclosures
Awards Close in Time to MNPI Disclosures [Table]
Net operating income
Operating Income (Loss)
Consolidated Entities [Domain]
Consolidated Entities [Domain]
Retained earnings
Retained Earnings (Accumulated Deficit)
Statement of Financial Position [Abstract]
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]
Lease revenue
Revenue Recognition, Leases [Policy Text Block]
Utility plant contributed by developers
Noncash or Part Noncash Acquisition, Fixed Assets Acquired
Change in value of life insurance contracts
Life Insurance, Corporate or Bank Owned, Change in Value
Current Fiscal Year End Date
Current Fiscal Year End Date
Subsequent Event Type [Domain]
Subsequent Event Type [Domain]
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]
Retirement Plan Type [Axis]
Retirement Plan Type [Axis]
Weighted-Average Grant-Date Fair Value
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Net other income
Other Nonoperating Income (Expense)
Adjustments to reconcile net income to net cash provided by operating activities:
Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract]
Financing activities:
Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract]
Reclassification out of Accumulated Other Comprehensive Income [Domain]
Reclassification out of Accumulated Other Comprehensive Income [Domain]
Equity Awards Adjustments, Excluding Value Reported in Compensation Table
Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member]
Camino Real
Camino Real [Member]
Camino Real
Variable Rate [Domain]
Variable Rate [Domain]
Cal Water
Cal Water [Member]
Represents California Water Company (Cal Water), a wholly-owned subsidiary of the Company.
Schedule of Fair Value of Long-term Debt
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]
Organization and Operations and Basis of Presentation
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]
Unrecognized tax benefits
Unrecognized Tax Benefits
Weighted average shares outstanding:
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
All Adjustments to Compensation
All Adjustments to Compensation [Member]
Amendment Flag
Amendment Flag
Shares authorized to be issued under the plan (in shares)
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized
Other Benefits
Other Postretirement Benefits Plan [Member]
Termination Date
Trading Arrangement Termination Date
Net cash provided by financing activities
Cash Provided by (Used in) Financing Activity, Including Discontinued Operation
Maintenance
Utilities Operating Expense, Maintenance
Insider Trading Policies and Procedures Adopted
Insider Trading Policies and Procedures Adopted [Flag]
Measure:
Measure [Axis]
Performance criteria adjustment (in shares)
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Performance Criteria Adjustment
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Performance Criteria Adjustment
Schedule of Regulatory Assets and Liabilities
Schedule of Regulatory Assets and Liabilities [Table Text Block]
Tabular disclosure of detailed information about regulatory assets and liabilities.
Basic (in shares)
Weighted Average Number of Shares Outstanding, Basic
Tax benefits that, if recognized, would affect the effective tax rate
Unrecognized Tax Benefits that Would Impact Effective Tax Rate
Director
Director [Member]
Summary of Amounts Reclassified out of AOCL by Component
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]
Subsequent Events [Abstract]
Subsequent Events [Abstract]
Segment Reporting [Abstract]
Pay vs Performance Disclosure, Table
Pay vs Performance [Table Text Block]
Other regulatory liabilities
Other Regulatory Assets (Liabilities) [Member]
PFAS settlement proceeds
PFAS Settlement Proceeds [Member]
PFAS Settlement Proceeds
Debt Disclosure [Abstract]
Debt Disclosure [Abstract]
Forgone Recovery due to Violation of Home Country Law, Amount
Forgone Recovery due to Violation of Home Country Law, Amount
Entity Tax Identification Number
Entity Tax Identification Number
Write-offs
Accounts Receivable, Allowance for Credit Loss, Writeoff
Forgone Recovery due to Expense of Enforcement, Amount
Forgone Recovery due to Expense of Enforcement, Amount
Consolidated Entities [Axis]
Consolidated Entities [Axis]
Stock-based Compensation
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, par value (in dollars per share)
Common Stock, Par or Stated Value Per Share
Amortization of defined benefit pension plans, net of tax of $150 and $60, respectively
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax
Proceeds from legal settlements
Proceeds from Legal Settlements
Interest expense
Interest Expense, Nonoperating
Trading Arrangement:
Trading Arrangement [Axis]
Total Shareholder Return Amount
Total Shareholder Return Amount
Subsequent Event
Subsequent Events [Text Block]
Insider Trading Arrangements [Line Items]
Security Exchange Name
Security Exchange Name
Lease revenue
Lease Income
Short-term regulatory accounts
Short-term portion of the regulatory liabilities
Regulatory Liability, Current
Distribution to noncontrolling interest
Payments of Ordinary Dividends, Noncontrolling Interest
Accrued payables for investments in utility plant
Capital Expenditures Incurred but Not yet Paid
Maximum borrowing capacity
Line of Credit Facility, Maximum Borrowing Capacity
Percentage increase in regulated revenue
Increase (Decrease) In Regulated Operating Revenue Expected In Future Periods, Percent
Increase (Decrease) In Regulated Operating Revenue Expected In Future Periods, Percent
Contributions in aid of construction
Contributions in Aid of Construction
Pension Adjustments Prior Service Cost
Pension Adjustments Prior Service Cost [Member]
Repurchase of common stock (in shares)
Stock Repurchased During Period, Shares
Material Terms of Trading Arrangement
Material Terms of Trading Arrangement [Text Block]
Average borrowing rate
Line of Credit Facility, Interest Rate During Period
Issuance of common stock
Stock Issued During Period, Value, New Issues
Variable Rate [Axis]
Variable Rate [Axis]
Rule 10b5-1 Arrangement Adopted
Rule 10b5-1 Arrangement Adopted [Flag]
Cash and cash equivalents
Cash and Cash Equivalent
Counterparty Name [Axis]
Counterparty Name [Axis]
Subsequent Event [Line Items]
Subsequent Event [Line Items]
Common Stock
Common Stock [Member]
Pension and retiree group health
Pension And Post Retirement Benefits [Member]
Discloses the amount of regulatory asset arising from the difference between net periodic pension and postretirement benefit costs, according to US GAAP, and the amount considered for rate-making purposes, according the actions of the regulator.
Vested (in shares)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period
Net WRAM and MCBA long-term payable
Net WRAM and MCBA Long-term Payable [Member]
Net WRAM and MCBA Long-term Payable [Member]
Entity Incorporation, State or Country Code
Entity Incorporation, State or Country Code
Non-NEOs
Non-NEOs [Member]
Change in cash, cash equivalents, and restricted cash
Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation