75000 - Document - Document and Entity Information
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75010 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME
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75020 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical)
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75030 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS
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75040 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)
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75050 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
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75060 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF EQUITY
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995455 - Disclosure - Summary of Significant Accounting Policies
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995465 - Disclosure - New Accounting Standards
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995475 - Disclosure - Balance Sheet Components
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995485 - Disclosure - Revenue
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995495 - Disclosure - Equity Method Investments
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995505 - Disclosure - Leases
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995515 - Disclosure - Derivatives and Risk Management
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995525 - Disclosure - Pension Plans and Other Postretirement Benefit Plans
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995535 - Disclosure - Income Taxes
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995545 - Disclosure - Short-Term Borrowings
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995555 - Disclosure - Long-Term Debt
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995565 - Disclosure - Long-Term Debt to Affiliated Trusts
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995575 - Disclosure - Fair Value
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995585 - Disclosure - Common Stock
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995595 - Disclosure - Accumulated Other Comprehensive Loss
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995605 - Disclosure - Earnings Per Common Share
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995615 - Disclosure - Commitments and Contingencies
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995625 - Disclosure - Information by Business Segments
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995635 - Disclosure - Summary of Significant Accounting Policies (Policies)
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995645 - Disclosure - Balance Sheet Components (Tables)
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995655 - Disclosure - Revenue (Tables)
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995665 - Disclosure - Derivatives and Risk Management (Tables)
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995675 - Disclosure - Pension Plans and Other Postretirement Benefit Plans (Tables)
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995685 - Disclosure - Income Taxes (Tables)
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995695 - Disclosure - Short-Term Borrowings (Tables)
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995705 - Disclosure - Long-Term Debt to Affiliated Trusts (Tables)
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995715 - Disclosure - Fair Value (Tables)
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995725 - Disclosure - Accumulated Other Comprehensive Loss (Tables)
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995735 - Disclosure - Earnings Per Common Share (Tables)
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995745 - Disclosure - Commitments and Contingencies (Tables)
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995755 - Disclosure - Information by Business Segments (Tables)
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995765 - Disclosure - New Accounting Standards - Additional Information (Details)
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995775 - Disclosure - Balance Sheet Components - Schedule of Inventory (Details)
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995785 - Disclosure - Balance Sheet Components - Schedule of Other Current Assets (Details)
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995795 - Disclosure - Balance Sheet Components - Schedule of Net Utility Property Recorded at Original Cost Net of Accumulated Depreciation (Details)
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995805 - Disclosure - Balance Sheet Components - Other Property and Investments-Net and Other Non-current Assets (Details)
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995815 - Disclosure - Balance Sheet Components - Other Current Liabilities (Details)
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995825 - Disclosure - Balance Sheet Components - Schedule of Other Non-Current Liabilities and Deferred Credits (Details)
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995835 - Disclosure - Balance Sheet Components - Schedule of Regulatory Assets and Liabilities (Details)
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995845 - Disclosure - Revenue - Schedule of Utilities Operating Revenue Expense Taxes (Details)
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995855 - Disclosure - Revenue - Additional Information (Details)
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995865 - Disclosure - Revenue - Disaggregation of Revenue (Details)
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995875 - Disclosure - Leases - Additional Information (Details)
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995885 - Disclosure - Equity Method Investments - Additional Information (Details)
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995895 - Disclosure - Derivatives and Risk Management - Schedule of Energy Commodity Derivative Volumes (Details)
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995895 - Disclosure - Derivatives and Risk Management - Schedule of Energy Commodity Derivative Volumes (Details) [Default]
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995905 - Disclosure - Derivatives and Risk Management - Additional Information (Details)
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995905 - Disclosure - Derivatives and Risk Management - Additional Information (Details) [Default]
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995915 - Disclosure - Derivatives and Risk Management -Schedules of Fair Values and Locations of Energy Commodity Derivative Instruments (Details)
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995925 - Disclosure - Derivatives and Risk Management - Schedules of Fair Values and Locations of Derivative Instruments (Details)
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995925 - Disclosure - Derivatives and Risk Management - Schedules of Fair Values and Locations of Derivative Instruments (Details) [Default]
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995935 - Disclosure - Derivatives and Risk Management - Schedule of Collateral Outstanding Related to Energy Commodity Derivative Instruments (Details)
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995945 - Disclosure - Pension Plans and Other Postretirement Benefit Plans - Additional Information (Details)
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995955 - Disclosure - Pension Plans and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Costs (Details)
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995965 - Disclosure - Income Taxes - Summary of Significant Factors Impact on Difference Between Effective Tax Rate and Federal Statutory Rate (Details)
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995975 - Disclosure - Income Taxes - Additional Information (Details)
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995985 - Disclosure - Short-Term Borrowings - Additional Information (Details)
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995995 - Disclosure - Short-Term Borrowings - Schedule of Balances Outstanding and Interest Rates of Borrowings (Details)
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996005 - Disclosure - Short-Term Borrowings - Schedule of Balances Outstanding and Interest Rates of Borrowings (Parenthetical) (Details)
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996015 - Disclosure - Long-Term Debt - Additional Information (Details)
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996025 - Disclosure - Long-Term Debt to Affiliated Trusts - Additional Information (Details)
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996035 - Disclosure - Long-Term Debt to Affiliated Trusts - Schedule of Distribution Rates Paid (Details)
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996045 - Disclosure - Fair Value - Schedule of Carrying Value and Estimated Fair Value of Financial Instruments (Details)
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996055 - Disclosure - Fair Value - Additional Information (Details)
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996065 - Disclosure - Fair Value - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details)
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996075 - Disclosure - Fair Value - Schedule of Quantitative Information (Details)
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996085 - Disclosure - Fair Value - Schedule of Activity for Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) (Details)
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996095 - Disclosure - Common Stock - Additional Information (Details)
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996105 - Disclosure - Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss, Net of Tax (Details)
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996115 - Disclosure - Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss, Net of Tax (Parenthetical) (Details)
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996125 - Disclosure - Accumulated Other Comprehensive Loss - Reclassification out of Accumulated Other Comprehensive Loss (Details)
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996135 - Disclosure - Earnings Per Common Share - Schedule of Computation of Basic and Diluted Earnings Per Common Share (Details)
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996145 - Disclosure - Earnings Per Common Share - Additional Information (Details)
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996155 - Disclosure - Commitments and Contingencies - Additional Information (Details)
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996165 - Disclosure - Commitments and Contingencies - Ownership and Operating Interest Percentage (Details)
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996175 - Disclosure - Information by Business Segments - Additional Information (Details)
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996185 - Disclosure - Information by Business Segments - Schedule of Business Segments (Details)
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Short-Term Debt [Text Block]
Committed Lines of Credit
Short-Term Borrowings
Line of Credit Facility [Line Items]
Settlement Amount
Payments for Legal Settlements
Deferrals And Amortizations For Rate Refunds To Customers
Deferrals And Amortizations For Rate Refunds To Customers
Deferrals and amortizations for rate refunds to customers
Year one
Energy Commodity Derivative Expected To Be Settle Year One
Energy Commodity Derivative Expected To Be Settle Year One
2021
Balance Sheet Related Disclosures [Abstract]
Scenario [Axis]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]
Schedules of Fair Values and Locations of Energy Commodity Derivative Instruments
Common Stock, Dividends, Per Share, Cash Paid
Dividends declared per common share
Electric.
Electric [Member]
Electric [Member]
Sales Agency Agreement
Sales Agency Agreement [Member]
Sales Agency Agreement [Member]
Sales Agency Agreement [Member]
Mandatory Cash Settlement Date
Derivative, Description of Terms
Number of actions on behalf of individual plaintiffs.
Number of actions on behalf of individual plaintiffs
Regulatory Assets, Non-Current
Regulatory Asset, Noncurrent
Non-current regulatory assets
Measurement Input, Share Price [Member]
Issuance Price Per Share [Member]
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset, Total
Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset
Counterparty and Cash Collateral Netting, Assets
Other Current Liabilities [Table Text Block]
Other Current Liabilities
Amount outstanding under committed line of credit
Long-term Line of Credit, Total
Balance outstanding at end of period
Borrowings outstanding at end of period
Outstanding under the committed line of credit
FairValue assets and liabilities measured on recurring basis unobservable input reconciliation.
Schedule of Activity for Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)
Debt Instrument, Basis Spread on Variable Rate
Debt instrument, basis spread on variable rate
Measurement input annual revenues.
Measurement Input Annual Revenues [Member]
Annual Revenues [Member]
Fixed Income Funds [Member]
Fixed Income Funds [Member]
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset, Total
Derivative Liability, Subject to Master Netting Arrangement, Gross Asset and Collateral, Right to Reclaim Cash, Offset
Counterparty and Cash Collateral Netting, Liabilities
Commitments and Contingencies
Commitments and Contingencies (See Notes to Condensed Consolidated Financial Statements)
Commodity Contract [Member]
Commodity Contracts [Member]
Weighted Average Number of Shares Outstanding, Diluted
Weighted-average common shares outstanding (thousands), diluted
Weighted-average number of common shares outstanding-diluted
Other deferred debits and credits.
Other Deferred Debits And Credits
Other deferred debits and credits
Deferred Derivative Gain (Loss) [Member]
Interest Rate Swaps [Member]
Minimum [Member]
Minimum [Member]
Repayment of Long-Term Debt, Long-Term Lease Obligation, and Capital Security, Total
Repayment of Long-Term Debt, Long-Term Lease Obligation, and Capital Security
Maturity of long-term debt and finance leases
Maturity of long-term debt and finance leases
Liability, Defined Benefit Plan, Current
Pensions and other postretirement benefits
Adjustment in decoupling regulatory deferral.
Adjustment In Decoupling Regulatory Deferral
Change in decoupling regulatory deferral
Letter of Credit [Member]
Letter of Credit [Member]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, Total
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax
Other Comprehensive Income (Loss), Defined Benefit Plan, after Reclassification Adjustment, Tax
Finance Lease [Member]
Finance Lease [Member]
Finance Lease [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure
Transaction/Delivery Volumes
Asplundh Tree Company And CN Utility Consulting [Member]
Asplundh Tree Company and CN Utility Consulting.
Asplundh Tree Company and CN Utility Consulting [Member]
Investment, Name [Axis]
Evaluated Power Capacity
Evaluated Power Capacity
Evaluated Power Capacity
Fair Value, Recurring [Member]
Fair Value, Recurring [Member]
Consolidated Entities [Domain]
Common Stock, Shares, Issued, Total
Common Stock, Shares, Issued
Common stock, shares, issued
Segment Reporting [Line Items]
Segment Reporting Information [Line Items]
Regulatory Assets, Current
Regulatory Asset, Current
Regulatory assets
Debt Instrument, Face Amount
Principal amount
Carrying amount
Number of collective bargaining agreement term.
Number of Collective Bargaining Agreement Term
Agreement term
Income tax expense (benefit)
Income tax expense
Income tax benefit
Income tax expense
Effective tax rate
Agreement voting requirement
Agreement Voting Requirement Description
Agreement voting requirement description.
Counterparty Name [Domain]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Realized And Unrealized Gains Losses Included In Regulatory Assets
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Realized And Unrealized Gains Losses Included In Regulatory Assets
Included in regulatory assets/liabilities
Debt instrument basis tenor spread adjustment rate.
Debt Instrument Basis Tenor Spread Adjustment Rate
Debt instrument basis tenor spread adjustment rate
Percentage of non-service related net periodic benefit costs recorded to other expense.
Percentage Of Nonservice Related Net Periodic Benefit Costs Recorded To Other Expense
Percentage of non-service related net periodic benefit costs recorded to other expense
Estimated additional liability
Estimated additional liability
Energy
Energy [Domain]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3
Transfer of assets out of Level 3
Operating Segments [Member]
Operating Segments [Member]
Widman Action [Member]
Widman Action [Member]
Line of Credit Facility, Maximum Borrowing Capacity
Line of credit facility, maximum borrowing capacity
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, tax
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax, Total
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, tax
Line of credit facility expiration date.
Line Of Credit Facility Expiration Date
Line of credit facility, expiration date
Internally Derived Weighted Average Cost Of Gas [Member]
Internally Derived Weighted Average Cost Of Gas [Member]
Internally Derived Weighted Average Cost Of Gas [Member]
Subsequent Event Type [Domain]
Percentage of employees represented.
Percentage Of Employees Represented
Percentage of employees represented
Investments and Other Noncurrent Assets
Other property and investments-net and other non-current assets
Total
Investments and other Noncurrent Assets
Other comprehensive income (loss) adjustment from AOCI pension and other postretirement benefit plans for net prior service cost , adjustment due to effects of regulation
Other Comprehensive Income Loss Adjustment From A O C I Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Adjustment Due Effects Of Regulation
Adjustment due to effects of regulation
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]
Physical Sales [Member]
Physical sales.
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount
State income taxes, net of federal income tax effect
Payment for (Proceeds from) Other Investing Activity
Other
Percentage of service related net periodic benefit costs recorded to operating expenses.
Percentage Of Service Related Net Periodic Benefit Costs Recorded To Operating Expenses
Percentage of service related net periodic benefit costs recorded to operating expenses
First Mortgage Bonds Due in 2056 [Member]
First Mortgage Bonds Due in 2056.
First Mortgage Bonds Due in 2056
Schedule of Long-Term Debt Instruments [Table]
Debt Instrument [Table]
Percentage of service related net periodic benefit costs capitalized to utility property.
Percentage Of Service Related Net Periodic Benefit Costs Capitalized To Utility Property
Percentage of service related net periodic benefit costs capitalized to utility property
Rathdrum, Idaho Natural Gas Incident [Member]
Rathdrum, Idaho Natural Gas Incident.
Income Statement [Abstract]
Customers [Member]
Customer.
Customer [Member]
Other Regulatory Liabilities [Member]
Other Regulatory Liabilities [Member]
Comprehensive Income (Loss) Note [Text Block]
Accumulated Other Comprehensive Loss
Nature of business.
Nature Of Business Policy [Text Block]
Nature of Business
Additions emissions liability.
Additions Emissions Liability
Additions emissions liability
Retail electric.
Retail Electric [Member]
Retail Electric [Member]
Payment for Pension Benefits
Payment for pension benefits
Contributions to defined benefit pension plan
Industrial Electric [Member]
Industrial Electric [Member]
Industrial Electric [Member]
PacifiCorp [Member]
Pacificorp.
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Axis]
Reclassification out of Accumulated Other Comprehensive Income
Related and Nonrelated Parties [Domain]
Related Party
Utilities Operating Expense, Depreciation and Amortization
Depreciation and amortization
Basic
Earnings Per Share, Basic
Basic
Earnings Per Share, Basic, Total
Deferred Natural Gas Costs [Member]
Deferred Natural Gas Costs Liability [Member]
Deferred natural gas costs liability.
Number of equity investments measured at fair value on recurring basic.
Number Of Equity Investments Measured At Fair Value On Recurring Basic
Number of equity investments measured at fair value on recurring basic
Short-Term Bank Loans and Notes Payable
Credit agreement amount borrowed
Corporate Segment and Other Operating Segment [Member]
Corporate and Other [Member]
Emission Allowance
Emission allowance.
Emission allowances
Document Period End Date
Document Period End Date
Inventory, Raw Materials and Supplies, Gross, Total
Inventory, Raw Materials and Supplies, Gross
Materials and supplies
Deferred Power Costs [Member]
Power Deferrals Regulatory Assets [Member]
Power deferrals regulatory assets.
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation
Less: Accumulated depreciation and amortization
Payments to Acquire Property, Plant, and Equipment
Utility property capital expenditures (excluding equity-related AFUDC)
Payments to Acquire Property, Plant, and Equipment, Total
Debt Instrument [Line Items]
Debt Instrument [Line Items]
Financial [Member]
Financial [Member]
Financial [Member]
Common Stock, Shares Authorized
Common stock, shares authorized
Statement of Stockholders' Equity [Abstract]
Finance Lease, Right-of-Use Asset, after Accumulated Amortization
Finance lease ROU assets
Finance Lease, Right-of-Use Asset, after Accumulated Amortization, Total
Accumulated Deferred Investment Tax Credit
Deferred investment tax credits
Income (Loss) from Equity Method Investments
Equity method (earnings) losses
Equity method earnings (losses)
First Mortgage Bonds Due in 2029 [Member]
First Mortgage Bonds Due in 2029 [Member]
First Mortgage Bonds Due in 2029
Two thousand and twenty two term loan [Member]
Two Thousand And Twenty Two Term Loan [Member]
2022 Term Loan [Member]
Reclassification out of Accumulated Other Comprehensive Income [Domain]
Reclassification out of Accumulated Other Comprehensive Income
Pension and Other Postretirement Plans Costs [Member]
Pension and Other Postretirement Benefit Plans [Member]
Equity Method Investments and Joint Ventures [Abstract]
Investments [Domain]
Investments
Number Of Plaintiffs
Number Of Plaintiffs
Number of plaintiffs.
Other comprehensive loss
Other Comprehensive Income (Loss), Net of Tax
Other Comprehensive Income (Loss), Net of Tax, Total
Accounting Standards Update and Change in Accounting Principle [Text Block]
New Accounting Standards
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest rate
Debt instrument interest rate percentage
Debt Instrument, Interest Rate, Stated Percentage
Other income tax related liabilities.
Other Income Tax Related Liabilities [Member]
Other Income Tax Related Liabilities [Member]
Costs and Expenses
Total operating expenses
Schedule of distribution rates.
Schedule Of Distribution Rates [Table Text Block]
Schedule of Distribution Rates
Advanced Meter Infrastructure [Member]
Advanced Metering Infrastructure Costs [Member]
Disaggregation of Revenue [Table]
Disaggregation Of Revenue [Table]
Debt Instrument Year of Maturity
Debt Instrument Year of Maturity
Debt instrument year of maturity
Loss Contingency, Damages Sought, Value
Loss contingency, damages sought, value
Common Stock, No Par Value
Common stock, par value
Assets
Total Assets
Total assets
Title of 12(b) Security
Title of 12(b) Security
Schedule of Equity Method Investments [Line Items]
Loss Contingency, Nature [Domain]
Loss Contingency, Nature
Goodwill, Total
Goodwill, Ending Balance
Goodwill, Beginning Balance
Goodwill
Goodwill
Commercial electric.
Commercial Electric [Member]
Litigation settlement amount
Litigation Settlement, Amount Awarded to Other Party
Utility Plant Abandoned [Member]
Asset Impairment for Regulatory Action [Member]
Utility Plant to be Abandoned [Member]
Jointly Owned Utility Plant Capital Expenditures And Operating Costs In Excess Of Pro rata Amount
Jointly owned utility plant, capital expenditures and operating costs in excess of pro rata amount.
Capital expenditures and operating costs in excess of pro rata amount
Regulatory Asset [Domain]
Regulatory Asset
Notional Amount
Derivative, Notional Amount
Notional amount
Payments to acquire property plant and equipment excludes other business expenditure.
Payments To Acquire Property Plant And Equipment Excludes Other Business Expenditure
Capital expenditures
Provision For Rate Refund [Member]
Provision for rate refund.
Schedule of Net Benefit Costs [Table Text Block]
Components of Net Periodic Benefit Cost
Effective Income Tax Rate Reconciliation, Percent
Effective tax rate, Percent
Increased potential claim
Litigation Settlement Increased Potential Claim
Litigation settlement increased potential claim
Variable Rate [Axis]
Canada, Dollars
Canada, Dollars [Member]
Proceeds from issuance of long-term debt
Proceeds from Issuance of Long-Term Debt
Proceeds from Issuance of Long-term Debt, Total
Non Utility Revenue [Member]
Non-Utility Revenue [Member]
Non-Utility Revenue.
Location, Statement of Financial Position, Balance [Axis]
Interest rate swap liability.
Interest Rate Swaps [Member]
Interest Rate Swap Liability [Member]
Disaggregation of Revenue [Table Text Block]
Disaggregation of Revenue
Schedule of Business Segments
Segment Reporting [Table Text Block]
Derivative, Fair Value, Amount Offset Against Collateral, Net, Total
Derivative, Fair Value, Amount Offset Against Collateral, Net
Collateral Netted
Balance sheet offsetting
Alaska electric light power.
Alaska Electric Light Power [Member]
Alaska Electric Light & Power [Member]
Natural Gas [Member]
Natural Gas Operations [Member]
Natural gas operations.
Beginning Balance
Ending Balance
Equity, Attributable to Parent
Total shareholders’ equity
Valuation Approach and Technique [Domain]
Valuation Approach and Technique
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year
Expected contributions to pension plan
Residential Natural Gas [Member]
Residential Natural Gas [Member]
Residential Natural Gas [Member]
Other
Other Assets, Noncurrent, Total
Other Assets, Noncurrent
Collaborative Arrangement and Arrangement Other than Collaborative [Domain]
Income Tax Disclosure [Text Block]
Income Taxes
Schedule of Carrying Value and Estimated Fair Value of Financial Instruments
Fair Value, by Balance Sheet Grouping [Table Text Block]
Boyds Fire.
Boyds Fire [Member]
Boyds Fire [Member]
Property damages.
Property Damages [Member]
Property Damages [Member]
Earnings Per Share [Text Block]
Earnings Per Common Share
Long-Term Debt, Fair Value
Long-term Debt, Fair Value
Estimate of Fair Value Measurement [Member]
Estimate of Fair Value Measurement [Member]
Plaintiffs initially claimed damage
Total Plaintiffs Initially Claimed Damage
Total plaintiffs initially claimed damage.
Weighted Average [Member]
Weighted Average [Member]
Number of Reportable Segments
Number of reportable segments
Stockholders' Equity Note [Abstract]
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]
Reclassification out of Accumulated Other Comprehensive Loss
Derivative Instruments and Hedging Activities Disclosures [Table]
Derivative Instruments And Hedging Activities Disclosures [Table]
Year two
Energy Commodity Derivative Expected To Be Settle Year Two
Energy Commodity Derivative Expected To Be Settle Year Two
2022
Ending Balance
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs
Beginning Balance
Deferred Climate Commitment Act Costs [Member]
Deferred Climate Commitment Act Costs [Member]
Credit Facility [Axis]
Schedule of Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Axis]
Schedule of Financial Instruments Subject to Mandatory Redemption by Settlement Terms
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Other Non-Reportable Segment Items [Member]
Financial Purchases [Member]
Financial Purchases.
Stock, Class of Stock [Table]
Schedule Of Stock By Class [Table]
Line of credit, outstanding
Line of Credit, Current
Inventory, Policy [Policy Text Block]
Inventory
Agreement expiration month and year.
Agreement Expiration Month And Year
Agreement expiration month and year
Litigation Case [Axis]
Litigation Case
Loss Contingency Nature [Axis]
Loss Contingency Nature
Number of subrogation actions filed.
Number Of Subrogation Actions Filed
Number of subrogation actions filed
Geographical [Domain]
Geographical
Accrual for Taxes Other than Income Taxes, Current
Accrued taxes other than income taxes
Equity Securities, FV-NI, Current
Equity investments
Other Accrued Liabilities, Noncurrent
Other
Expected deliveries of energy commodity derivatives after four years
Energy commodity derivatives expected to be settle after year four.
Energy Commodity Derivatives Expected To Be Settle After Year Four
Fair Value of Financial Instruments, Policy [Policy Text Block]
Fair Value Measurements
Purchase [Member]
Purchase [Member]
Purchase [Member]
Litigation Status [Domain]
Statistical Measurement [Axis]
Statistical Measurement
Lancaster Power Purchase Agreement [Member]
Lancaster Power Purchase Agreement [Member]
Lancaster Power Purchase Agreement [Member]
Physical Purchases [Member]
Physical purchases.
Entity Interactive Data Current
Entity Interactive Data Current
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Defined Benefit and Postretirement Benefit Plans Adjustment Attributable to Parent [Member]
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount
Other
Year five
Energy Commodity Derivative Expected To Be Settle Year Five
Energy Commodity Derivative Expected To Be Settle Year Five
2025
Schedule of Assets Pledged as Collateral and Related Offsets [Table Text Block]
Scheduleof Assets Pledgedas Collateraland Related Offsets Table [Text Block]
Schedule of Collateral Outstanding Related to Energy Commodity Derivative Instruments
Common Stock, Value, Issued
Common Stock, Value, Issued, Ending Balance
Common Stock, Value, Issued, Beginning Balance
Common Stock, Value, Issued, Total
Common stock, no par value; 200,000 shares authorized; 83,752 and 82,193 shares issued and outstanding, respectively (shares in thousands)
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
Schedule of Computation of Basic and Diluted Earnings Per Common Share
Liabilities
Total liabilities
Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses
Other operating expenses
Ownership [Domain]
Ownership
Portland General Electric Company.
Portland General Electric Company [Member]
PGE [Member]
Avista utilities.
Avista Utilities [Member]
Avista Utilities [Member]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]
Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis
Product and Service [Axis]
Product and Service
Interest expense
Interest Expense Excluding Interest Expense To Related Party
Interest expense excluding interest expense to related party.
Interest expense
Road fire covered area.
Road Fire Covered Area
Road fire covered area
Retained Earnings (Accumulated Deficit)
Retained earnings
Retained Earnings (Accumulated Deficit), Ending Balance
Retained Earnings (Accumulated Deficit), Beginning Balance
Retained Earnings (Accumulated Deficit), Total
Unspecified Damages [Member]
Unspecified Damages [Member]
Unspecified damages.
Line of Credit Facility, Covenant Terms, Maximum Debt to Equity Ratio
Lineof Credit Facility Covenant Terms Maximum Debtto Equity Ratio
Line of credit facility, covenant terms, maximum debt to equity ratio
Fair Value, Inputs, Level 3 [Member]
Level 3 [Member]
Commercial Natural Gas.
Commercial Natural Gas [Member]
Commercial Natural Gas [Member]
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]
Payments to acquire transferable tax credits
Payments to Acquire Transferable Tax Credits
Payments to acquire transferable tax credits.
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]
Schedule of Energy Commodity Derivative Volumes
Utilities Operating Expense, Taxes
Taxes other than income taxes
Year three
Energy Commodity Derivative Expected To Be Settle Year Three
Energy Commodity Derivative Expected To Be Settle Year Three
2023
Increase (Decrease) in Accounts Payable, Total
Increase (Decrease) in Accounts Payable
Accounts payable
IBEW chapter.
IBEW chapter
Equity Method Investment, Ownership Percentage
Equity method investment, percentage
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases
Purchases and debt conversions
Revenues [Abstract]
Utility revenues:
Fair Value, by Balance Sheet Grouping [Table]
Fair Value By Balance Sheet Grouping [Table]
Derivative Revenues
Derivative revenues
Derivative Revenues
Percentage of non-service related net periodic benefit costs capitalized to regulatory assets.
Percentage Of Nonservice Related Net Periodic Benefit Costs Capitalized To Regulatory Assets
Percentage of non-service related net periodic benefit costs capitalized to regulatory assets
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Line Items]
Fair Value Measurement Inputs and Valuation Techniques [Table]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Table]
Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract]
Changes in certain current assets and liabilities:
Measurement input market exit reduction.
Measurement Input Market Exit Reduction [Member]
Market Exit Reduction [Member]
Stock Issued During Period, Shares, New Issues
Shares issued
Shares issued under sales agency agreements
Other Assets, Miscellaneous, Current
Other
Deferred Income Tax Liabilities, Net, Total
Deferred Income Tax Liabilities, Net
Deferred income taxes
Variable Rate [Domain]
Damage from Fire, Explosion or Other Hazard [Member]
Damage from Fire [Member]
Depreciation And Amortization Expense
Depreciation And Amortization Expense
Depreciation and amortization
Financial Liabilities Fair Value Disclosure
Financial Liabilities Fair Value Disclosure
Financial Liabilities Fair Value Disclosure, Total
Derivative Liability, Total
Derivative Liability
Derivative Liability
Derivative Liability
Accumulated Other Comprehensive Loss [Abstract]
Accumulated Other Comprehensive Loss [Abstract]
Derivative Liability, Statement of Financial Position [Extensible Enumeration]
Derivative revenues [Member]
Derivative Revenues [Member]
Derivative Revenues [Member]
Litigation settlement, agreed to settle all claims and allegations.
Litigation Settlement, Agreed To Settle All Claims And Allegations
Amout of settle all claims and allegations
Ownership and operating ownership interest percentage .
Ownership And Operating Ownership Interest Percentage [Table Text Block]
Ownership and Operating Ownership Interest Percentage
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]
Long-Term Debt [Text Block]
Long-Term Debt
Utility Revenue.
Utility Revenue [Member]
Utility Revenue [Member]
Transfer of assets into Level 3
Transfers in
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3
Defined Benefit Plan, Service Cost
Service cost
Fair Value Hierarchy and NAV [Axis]
Fair Value Hierarchy and NAV
Transfer of liabilities into Level 3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3
Defined Benefit Plan [Table]
Schedule Of Defined Benefit Plans Disclosures [Table]
Collective bargaining agreements avista utilities bargaining unit employees.
Collective Bargaining Agreements Avista Utilities Bargaining Unit Employees [Member]
Collective Bargaining Agreements Avista Utilities Bargaining Unit Employees [Member]
Settlement in Principle [Member]
Settlement in principle.
Settled in Principle [Member]
Public Utilities, Property, Plant and Equipment, Construction Work in Progress
Construction work in progress
Short [Member]
Sales [Member]
AFUDC Above FERC Allowed Rate [Member]
A F U D C Above F E R C Allowed Rate [Member]
Allowance for Funds Used During Construction above the Federal Energy and Regulatory Commission allowed capitalization rate.
Litigation Case [Domain]
Litigation Case
Customer [Domain]
Customer
Derivative [Line Items]
Derivative [Line Items]
Liabilities and Equity
Total liabilities and equity
Number of class action lawsuit.
Number of class action lawsuit
Debt Instrument, Description of Variable Rate Basis
Debt instrument, description of variable rate basis
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent, Total
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent
Net income (loss)
Number of period currency prices are settled with domestic country currency.
Number Of Period Currency Prices Are Settled With Domestic Country Currency
Number of days Canadian currency prices are settled with U.S. dollars
Lessee, Lease, Description [Table]
Document Fiscal Period Focus
Document Fiscal Period Focus
Revenue, Remaining Performance Obligation, Amount
Revenue, Remaining Performance Obligation, Amount
Derivatives, Fair Value [Line Items]
Derivatives, Fair Value [Line Items]
Short-term Debt, Total
Short-Term Debt
Short-term borrowings
Measurement Input, Quoted Price [Member]
Measurement Input, Quoted Price [Member]
United States of America, Dollars
United States of America, Dollars [Member]
Schedule of Inventory, Current [Table Text Block]
Schedule of Inventory
August Fire Activity.
August Fire Activity [Member]
Proceeds from Equity Method Investment, Distribution
Distributions from equity method investments
Power and natural gas cost amortizations (deferrals), net
Power And Natural Gas Cost Amortization Deferrals Net
Power and natural gas cost amortization deferrals net.
Costs and Expenses [Abstract]
Operating Expenses:
Currency [Axis]
Currency
Letters of Credit Outstanding, Amount
Letters of credit outstanding
Letters of credit outstanding at end of period
CANADA
Canadian [Member]
Sale of Stock [Axis]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]
Net decrease in cash and cash equivalents
Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation
Net increase (decrease) in cash and cash equivalents
Entity Current Reporting Status
Entity Current Reporting Status
Fair Value, Inputs, Level 1 [Member]
Level 1 [Member]
Energy commodity derivatives expected to be settle after year three.
Energy Commodity Derivatives Expected To Be Settle After Year Three
Expected deliveries of energy commodity derivatives after three years
Equity investments terminal date.
Equity Investments Terminal Date
Equity investments, terminal date
Accounts Payable, Current, Total
Accounts Payable, Current
Accounts payable
Investment Type [Axis]
Investment Type
Financial Instrument [Axis]
Financial Instrument
Assets, Fair Value Disclosure
Assets, Fair Value Disclosure
Assets, Fair Value Disclosure, Total
Document Transition Report
Document Transition Report
Increase (Decrease) in Deposit Assets
Increase (Decrease) in Deposit Assets, Total
Collateral for derivative instruments
Liability Class [Axis]
Liability Class
Commitments and Contingencies Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, CARES Act Tax Benefit Amortization
Effective Income Tax Rate Reconciliation, CARES Act Tax Benefit Amortization.
CARES Act tax benefit amortization
CARES Act tax benefit amortization
Defined Benefit Plan, Expected Return (Loss) on Plan Assets
Expected return on plan assets
Accrued Vacation, Current
Employee paid time off accruals
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3
Transfer of liabilities out of Level 3
Increase (Decrease) in Inventories
Increase (Decrease) in Inventories, Total
Inventory
Climate commitment act obligations noncurrent.
Climate Commitment Act Obligations Noncurrent
Climate Commitment Act obligations
Liabilities, Current [Abstract]
Current Liabilities:
Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Equity:
Avista Corporation Shareholders Equity:
Pension and Other Postretirement Benefits Cost (Reversal of Cost)
Pension and other postretirement benefit expense
Pension and Other Postretirement Benefits Cost (Reversal of Cost), Total
Realized And Unrealized Gains On Assets And Investments
Realized and unrealized gains on assets and Investments.
Realized and unrealized (gains) losses on assets and investments
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value
Beginning Balance
Ending Balance
Equity investments annual revenues.
Equity Investments Annual Revenues
Equity investments, annual revenues
Settled Litigation [Member]
Settled [Member]
Common Stock [Member]
Common Stock [Member]
Retirement Plan Type [Axis]
Retirement Plan Type
Derivative Instruments and Hedging Activities Disclosure [Text Block]
Derivatives and Risk Management
Accounting Standards Update and Change in Accounting Principle [Abstract]
Line Of Credit Facility Granted Additional Extenstion Period
Line of credit facility granted additional extenstion period
Line of credit facility granted additional extension period
Residential Electric [Member]
Residential Electric [Member]
Residential Electric [Member]
Weighted Average Number of Shares Outstanding, Diluted, Adjustment [Abstract]
Effect of dilutive securities:
Credit Facility [Domain]
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent
State income taxes, net of federal income tax effect, Percent
Statistical Measurement [Domain]
Statistical Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Percentage of largest group of employees represented.
Percentage Of Largest Group Of Employees Represented
Percentage of largest group of employees represented
Industrial and Interruptible Natural Gas [Member]
Industrialand Interruptible Natural Gas [Member]
Industrial and Interruptible Natural Gas [Member]
Long-Term Debt to Affiliated Trust [Abstract]
Long Term Debt To Affiliated Trust [Abstract]
Prepaid Expense, Current, Total
Prepaid Expense, Current
Prepayments
Shareholders' Equity:
Equity, Attributable to Parent [Abstract]
Long Term Debt To Affiliated Trusts Disclosure [Text Block]
Long Term Debt To Affiliated Trusts Disclosure [Text Block]
Long- Term Debt To Affiliated Trusts
Weighted Average Number of Shares Outstanding, Basic
Weighted-average common shares outstanding (thousands), basic
Weighted-average number of common shares outstanding-basic
Weighted Average Number of Shares Outstanding, Basic, Total
Power and natural gas cost deferrals, net
Power and natural gas cost deferrals net
Power and natural gas cost deferrals net.
Climate Commitment Act.
Climate Commitment Act [Member]
Climate Commitment Act [Member]
Assets [Abstract]
Assets:
Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset
Collateral posted for derivative instruments after netting with outstanding derivatives
Entity Central Index Key
Entity Central Index Key
Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table]
Fair Values Derivatives Balance Sheet Location By Derivative Contract Type By Hedging Designation [Table]
NorthWestern Corporations.
NorthWestern Corporations [Member]
NorthWestern [Member]
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Class of Stock [Line Items]
Class Of Stock [Line Items]
Total
Other Liabilities, Current
Other current liabilities
Consolidation Items [Axis]
Consolidation Items
Current Fiscal Year End Date
Current Fiscal Year End Date
Derivative [Table]
Derivative [Table]
Number of Interest Rate Derivatives Held
Number of Contracts
Financial Sales [Member]
Financial Sales.
Talen [Member]
Talen.
Derivative Assets and Liabilities
Derivatives, Reporting of Derivative Activity [Policy Text Block]
Document Quarterly Report
Document Quarterly Report
Debt Instrument, Maturity Date
Maturity date
Line of Credit Facility, Interest Rate at Period End
Average interest rate on borrowings at end of period
Average interest rate on borrowings
Physical [Member]
Physical [Member]
Physical [Member]
Fair Value, Inputs, Level 2 [Member]
Level 2 [Member]
Other Natural Gas [Member]
Other Natural Gas [Member]
Other Natural Gas Revenues from Contracts With Customers [Member]
Asset Retirement Obligation, Ending Balance
Asset Retirement Obligation, Beginning Balance
Asset Retirement Obligation, Total
Asset Retirement Obligation
Asset retirement obligations
Cash Provided by (Used in) Operating Activity, Including Discontinued Operation
Net cash provided by operating activities
Entity Incorporation, State or Country Code
Entity Incorporation, State or Country Code
Derivative liabilities net of collateral
Derivative Liability, Noncurrent
Derivative liabilities
Diluted
Earnings Per Share, Diluted, Total
Earnings Per Share, Diluted
Diluted
Road 11 Fire [Member]
Road Eleven Fire Member
Road eleven fire.
Net income
Net income and Comprehensive income
Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture
Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture, Total
Equity compensation expense
Ownership [Axis]
Ownership
Increase (Decrease) in Other Operating Assets, Total
Increase (Decrease) in Other Operating Assets
Other current assets
Deferred Power Costs [Member]
Power Deferrals Regulatory Liability [Member]
Power Deferrals Regulatory Liability [Member]
Commitments and Contingencies Disclosure [Text Block]
Commitments and Contingencies
CN Utility Consulting [Member]
CN Utility Consulting [Member]
Supplemental Balance Sheet Disclosures [Text Block]
Balance Sheet Components
Lease Contractual Term [Domain]
Schedule of Other Assets, Noncurrent [Table Text Block]
Other Property and Investments-Net and Other Non-Current Assets
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount
U.S. federal statutory tax rate
Non Regulated Property
Non-utility property
Non regulated property.
Insurance Settlements Receivable
Insurance Settlements Receivable
Other Utility Revenues [Member]
Other Utility Revenues [Member]
Other Utility Revenues [Member]
IDAHO
Idaho [Member]
Number of Private Plaintiffs
Number of private plaintiffs.
Number of private plaintiffs
Investment, Type [Extensible Enumeration]
Measurement Frequency [Domain]
Measurement Frequency
Income Taxes Receivable, Current
Income taxes receivable
Scenario [Domain]
Equity Components [Axis]
Equity Components
Investing Activities:
Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract]
Regulatory Liabilities, Current
Regulatory Liability, Current
Regulatory liabilities
Regulatory Liability, Current, Total
Statement of Cash Flows [Abstract]
Fair Value Hierarchy and NAV [Domain]
Fair Value Hierarchy and NAV
Income Tax Disclosure [Abstract]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax, Total
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax
Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $100 and $95, respectively
Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $100 and $95, respectively
Fair Value Disclosures [Text Block]
Fair Value
Finance Lease, Liability, Noncurrent
Finance lease liabilities
Depreciation, Depletion and Amortization, Total
Depreciation and amortization
Depreciation, Depletion and Amortization
EIP I
Energy Impact Partners I [Member]
Energy Impact Partners I.
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity
Equity-related AFUDC
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements
Settlements
Retirement Benefits, Description [Abstract]
Retirement Benefits, Description [Abstract]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest
Income before income taxes and equity method earnings (losses)
Income before income taxes and equity method earnings (losses)
Derivative Contract [Domain]
Derivative Contract
Debt Instrument, Issuance Date
Debt instrument issuance date
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount
Antidilutive securities excluded from computation of earnings per share, amount
Loss on acceleration of unrecognized priof service costs
Amortization of prior service cost (credit)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)
Counterparty Name [Axis]
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Loss [Member]
Derivative, Forward Price
Derivative, Forward Price
Financial Instruments Subject to Mandatory Redemption, Financial Instrument [Domain]
Financial Instruments Subject to Mandatory Redemption, Financial Instrument
Excepted to Issue Additional Debt
Excepted to issue additional debt
Excepted to issue additional debt
Fair value measurement with unobservable inputs reconciliation recurring basis asset other.
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Other
Other
Non utility operating expense.
Non Utility Operating Expense
Non-utility operating expenses
Interest Expense Including Affiliated Trusts
Interest Expense Including Affiliated Trusts
Interest expense
Total
Inventory, Net
Inventory
Loss Contingency, Estimate of Possible Loss
Estimate of liability related to claim
Revolving credit agreement.
Revolving Credit Agreement [Member]
Revolving credit agreement [Member]
Derivative, Net Liability Position, Aggregate Fair Value
Liabilities with credit-risk-related contingent features
Foreign Exchange Contract [Member]
Foreign Exchange Contract [Member]
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]
Line of credit facility additional expiration period.
Line Of Credit Facility Additional Expiration Period
Line of credit facility additional expiration period
Accrued Liabilities, Current, Total
Accrued Liabilities, Current
Other
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Energy Commodity Derivative Volumes [Line Items]
Customer [Axis]
Customer
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions, Total
Distributions from equity method investments
Short-Term Debt [Line Items]
Short-term Debt [Line Items]
Short-Term Debt [Table]
Schedule Of Short Term Debt [Table]
Measurement Input, Discount Rate [Member]
Discount Rate [Member]
Public Utilities, Property, Plant and Equipment, Plant in Service, Total
Public Utilities, Property, Plant and Equipment, Plant in Service
Utility plant in service
NonEconomic Damage [Member]
NonEconomic Damage [Member]
Document Type
Document Type
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Disclosure [Line Items]
Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract]
Operating Activities:
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]
Liabilities and Equity [Abstract]
Avista Corporation Shareholders Equity:
Equity Method Investment [Table]
Lessee, Lease, Description [Line Items]
Subsequent Event [Member]
Subsequent Event [Member]
Subsequent Event
Accounting Standards Update [Extensible Enumeration]
Operating Income (Loss)
Income (loss) from operations
Income from operations
Derivative Instruments and Hedges, Assets [Abstract]
Interest expense to affiliated trust.
Interest Expense To Affiliated Trust
Interest expense to affiliated trusts
Estimate Fair Value Decrease of Investment be Recorded in Fourth Quarter
Estimate fair value decrease of investment be recorded in fourth quarter.
Estimate fair value decrease of investment be recorded in 4th quarter
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]
Schedule of Accumulated Other Comprehensive Loss, Net of Tax
Dividends on common stock
Dividends, Common Stock, Cash
Loss Contingency Claim Amount Remains Unsettled.
Loss Contingency Claim Amount Remains Unsettled.
Claim amount remains unsettled
Public Street and Highway Lighting Electric [Member]
Public Streetand Highway Lighting Electric [Member]
Public Street and Highway Lighting Electric [Member]
Segment Reporting [Table]
Schedule Of Segment Reporting Information By Segment [Table]
Schedule of net utility property.
Schedule Of Net Utility Property Table [Text Block]
Schedule of Net Utility Property Recorded at Original Cost Net of Accumulated Depreciation
Asset Class
Asset Class [Domain]
Securities Act File Number
Entity File Number
Defined Benefit Plan, Amortization of Gain (Loss)
Net loss recognition
Estimate Fair Value Increase of Investment be Recorded in Third Quarter
Estimate fair value increase of Investment be recorded in third quarter
Estimate fair value increase of Investment be recorded in 3rd quarter
Payments to acquire equity and property investments.
Payments To Acquire Equity And Property Investments
Investments made in equity investments and property
Revenue from Contract with Customer [Text Block]
Revenue
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]
Change in accounting principle accounting standards update, immaterial effect
Collateral Already Posted, Aggregate Fair Value
Cash collateral posted
Increase (Decrease) in Accounts and Notes Receivable
Accounts and notes receivable
Retirement Plan Type [Domain]
Retirement Plan Type
Location, Statement of Income, Balance [Axis]
Estimate of Remaining Losses Related to Unsettled Claims
Estimate of remaining losses related to the unsettled claims.
Estimate of remaining losses related to the unsettled claims
Retained Earnings [Member]
Retained Earnings [Member]
Proceeds from (Payment for) Other Financing Activity
Other
Interest Payable, Current
Accrued interest
Entity Registrant Name
Entity Registrant Name
Long-term prepaid license fees
Long-term Prepaid License Fees
Long-term Prepaid License Fees
Accounting Policies [Abstract]
Net income
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total
Nonrelated Party [Member]
Non Affiliated Trusts [Member]
Unit Four.
Unit Four [Member]
Unit 4 [Member]
Intersegment Eliminations [Member]
Eliminations [Member]
Accrued losses related to the Babb Road litigation,
Loss Contingency Accrual, Loss (Reversal of Loss)
Entity Address, Address Line One
Entity Address, Address Line One
Total Settlement Amount
Total settlement amount
Total settlement amount.
Excess Deferred Income Taxes [Member]
Deferred Income Tax Charge [Member]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, before tax
Short-Term Debt, Percentage Bearing Fixed Interest Rate
Bearing interest rate
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
All Currencies [Domain]
All Currencies
Proceeds from (Repayments of) Short-term Debt, Total
Proceeds from (Repayments of) Short-Term Debt
Net decrease in short-term borrowings
Net (decrease) increase in short-term borrowings
Assets, Current
Total current assets
Accrued losses related to the Babb Road litigation
Loss Contingency Accrual, Product Liability, Net
Loss Contingency Accrual, Product Liability, Net, Total
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Net periodic benefit cost
Collective bargaining agreements avista utilities employees.
Collective Bargaining Agreements Avista Utilities Employees [Member]
Collective Bargaining Agreements Avista Utilities Employees [Member]
Segments
Segments [Axis]
Year four
Energy Commodity Derivative Expected To Be Settle Year Four
Energy Commodity Derivative Expected To Be Settle Year Four
2024
Loss Contingencies [Line Items]
Loss Contingencies [Line Items]
Non-settling parties are claiming damages
Non-Settling Parties are Claiming Damages
Non-settling parties are claiming damages.
Litigation Settlement
Gain (Loss) from Litigation Settlement
Gain (Loss) from Litigation Settlement, Total
Cash received for settlement of interest rate swap agreements
Proceeds from Settlement Of Derivative Instruments
Proceeds from Settlement of Derivative Instruments.
Deferred Income Tax Expense (Benefit)
Deferred Income Tax Expense (Benefit), Total
Provision for (benefit from) deferred income taxes
Long-Term Debt, Measurement Input
Long-term debt, measurement input
Long [Member]
Purchase [Member]
Entity Small Business
Entity Small Business
Long-term Debt, Excluding Current Maturities, Total
Long-Term Debt, Excluding Current Maturities
Long-term debt
Pension Plan [Member]
Pension Plans, Defined Benefit [Member]
Pension Benefits [Member]
Effective Income Tax Rate Reconciliation, Excess Deferred Tax Amortization, Amount
Effective Income Tax Rate Reconciliation, Excess Deferred Tax Amortization, Amount.
Excess deferred tax amortization
Excess deferred tax amortization
Insurance Deferrals [Member]
Insurance deferrals.
Equity investment member
Equity Investment [Member]
Equity Investment [Member]
Investment, Name [Domain]
Schedule of regulated asset and liability
Schedule Of Regulated Asset And Liability Table [Text Block]
Schedule of Regulatory Assets and Liabilities
Incremental Common Shares Attributable to Share-based Payment Arrangements, Total
Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements
Performance and restricted stock awards
Long-Term Debt, Type [Axis]
Long-term Debt, Type
Other Inventory, Gross, Total
Fuel stock
Other Inventory, Gross
Customer deposits
Customer Refund Liability, Current
Significant Accounting Policies [Text Block]
Summary of Significant Accounting Policies
Accounts Receivable, after Allowance for Credit Loss, Current
Accounts Receivable, after Allowance for Credit Loss, Current, Total
Accounts receivable-less allowances of $6 and $5, respectively
Consolidation Items [Domain]
Consolidation Items
Change in Accounting Principle, Accounting Standards Update, Adoption Date
Change in accounting principle accounting standards update, adoption date
Transferable Tax Credits Purchased
Transferable tax credits purchased.
Transferable tax credits purchase
Equity Method Investments
Equity Method Investments and Joint Ventures Disclosure [Text Block]
1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member]
Nineteen Ninety Seven Floating Rate Junior Subordinated Deferrable Interest Debentures Series B [Member]
Nineteen Ninety Seven Floating Rate Junior Subordinated Deferrable Interest Debentures Series B [Member]
Position
Position [Axis]
Energy [Axis]
Energy
Decoupling Rebate [Member]
Decoupling [Member]
Decoupling [Member]
Earnings Per Share [Abstract]
Earnings per common share:
Derivative Asset
Derivative Asset
Derivative Asset, Total
Orofino fire.
Orofino Fire [Member]
Orofino Fire [Member]
Equity Method Investments, Fair Value Disclosure
Equity investments
Regulated Asset Liability [Table]
Regulated Asset Liability [Table]
Regulated Asset Liability [Table]
Equity Investments Probability Weighting
Equity Investments Probability Weighting
Equity Investments, probability weighting
Revenue from Contracts with Customers [Member]
Revenue from Contracts with Customers [Member]
Revenuefrom Contractswith Customers [Member]
Subsequent Event Type [Axis]
Colstrip Liabilities [Member]
Colstrip liabilities.
Colstrip [Member]
Long-term debt
Long-Term Line of Credit, Noncurrent
Number Of Employees Comprised
Number Of employees comprised.
Number of employees comprised
Product and Service [Domain]
Product and Service
Income tax related assets.
Income Tax Related Assets [Member]
Income Tax Related Assets [Member]
Accounts Receivable, Allowance for Credit Loss, Current
Accounts receivable, allowances
Equity [Text Block]
Common Stock
Measurement Frequency [Axis]
Measurement Frequency
Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract]
Financing Activities:
Fair Value by Liability Class [Domain]
Fair Value by Liability Class
Estimated loss related to investment of fair value
Estimated Loss Related to Investment of Fair Value
Estimated loss related to investment of fair value.
Puget Sound Energy Inc.
Puget Sound Energy Inc [Member]
PSE [Member]
Retail natural gas.
Retail Natural Gas [Member]
Retail Natural Gas [Member]
Consolidated Entities [Axis]
Economic Damage [Member]
Economic Damage [Member]
Economic damage.
Derivative Assets (Liabilities), at Fair Value, Net
Net Asset (Liability) on Balance Sheet
Entity Tax Identification Number
Entity Tax Identification Number
Agreement Expiration Year
Agreement expiration year.
Agreement expiration year
Other Utility Revenues [Member]
Other Non-utility Revenues
Other non-utility revenues.
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures, Total
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
Investment in affiliated trust
Valuation Approach and Technique [Axis]
Valuation Approach and Technique
Insurance Settlements Receivable, Current
Insurance proceeds receivable
Derivative Instrument [Axis]
Derivative Instrument
Equity Component [Domain]
Equity Component
Regulatory Asset [Axis]
Regulatory Asset
Entity Address, City or Town
Entity Address, City or Town
Measurement Input Type
Measurement Input Type [Domain]
Stock Issued During Period, Value, New Issues
Issuance of common stock, net of issuance costs
Investments, Fair Value Disclosure, Total
Investments, Fair Value Disclosure
Deferred compensation assets:
Regulatory Liability
Regulatory Liability [Domain]
Segments [Domain]
Segments
Utility operating expenses:
Utilities Operating Expense [Abstract]
Valuation Technique, Discounted Cash Flow [Member]
Discounted Cash Flows [Member]
Entity Common Stock, Shares Outstanding
Entity Common Stock, Shares Outstanding
Regulatory Asset Settlement [Member]
Regulatory Asset Settlement [Member]
Settlement with Coeur d'Alene Tribe [Member]
Equity Securities, FV-NI, Measurement Input
Equity investments, measurement input
Deferred Climate Commitment Act Revenues [Member]
Deferred climate commitment act revenues.
IBEW [Member]
I B E W [Member]
I B E W [Member]
[Table Text Block] for Schedule Of Utilities Operating Revenue and Expense Taxes - Utility-related taxes collected from customers and reported gross in the income statement [Table]
Schedule Of Utilities Operating Revenue Expense Taxes Table [Text Block]
Schedule of Utilities Operating Revenue Expense Taxes
Revenue from Alternative Revenue Programs (Decoupling)
Revenue From Alternative Revenue Programs
Alternative revenue programs
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Denominator:
Segment Reporting, Expense Information Used by CODM, Description
Measurement Basis [Axis]
Measurement Basis
Derivative Asset, Fair Value, Gross Asset, Total
Derivative Asset, Subject to Master Netting Arrangement, before Offset
Gross Asset
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, after tax
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax
Amortization of net loss
Statement [Table]
Statement [Table]
Operating Revenues:
Operating Income (Loss) [Abstract]
Washington [Member]
WASHINGTON
Other regulatory assets.
Other Regulatory Assets [Member]
Other utility revenues
Other Utility Revenues
Other Utility Revenues
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest
Income before income taxes
Income from continuing operations before income tax expense
Affiliated Entity [Member]
Affiliated Entity [Member]
Entity Shell Company
Entity Shell Company
Economic Losses Of Plaintiffs
Economic Losses Of Plaintiffs
Economic losses of plaintiffs.
Cash Provided by (Used in) Investing Activity, Including Discontinued Operation
Net cash used in investing activities
Liability, Defined Benefit Plan, Noncurrent, Total
Liability, Defined Benefit Plan, Noncurrent
Pensions and other postretirement benefits
Valuation, Market Approach [Member]
Market Approach [Member]
Statement [Line Items]
Statement [Line Items]
Number Of Employees Represented
Number Of employees represented.
Number of employees represented
Utilities operating expense (deferrals) for products and services.
Utilities Operating Expense Deferrals For Products And Services
Resource costs
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table]
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Table]
Maximum [Member]
Maximum [Member]
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount
Total other adjustments
Total other adjustments
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings
Recognized in net income
Debt Disclosure [Abstract]
Sale of Stock [Domain]
Common Stock Subject to Mandatory Redemption [Member]
Common Trust Securities [Member]
Effective Income Tax Reconciliation Flow Through Related To Deduction Of Meters And Mixed Service Cost
Effective income tax reconciliation flow through related to deduction of meters and mixed service cost.
Flow through related to deduction of meters and mixed service costs, Percent
Flow through related to deduction of meters and mixed service costs, Percent
Increase (Decrease) in Other Operating Liabilities
Other current liabilities
Increase (Decrease) in Other Operating Liabilities, Total
Interest income
Investment Income, Interest
Payments for Repurchase of Trust Preferred Securities
Payments for repurchase of trust preferred securities
Other Segment Income Expenses
Other segment income (expenses).
Other segment expenses (income)
Other segment expenses (income)
Other segment expenses
Excess deferred tax amortization,Percent
Effective Income Tax Rate Reconciliation, Excess deferred tax amortization, Percent
Effective Income Tax Rate Reconciliation, Excess deferred tax amortization, Percent.
Excess deferred tax amortization, Percent
Energy Commodity Derivative Expected to Be Settled in Remainder of Fiscal Year
Energy commodity derivative expected to be settled in remainder of fiscal year.
Remainder 2026
Natural Gas Exchange Agreements [Member]
Natural Gas Exchange Agreements [Member]
Natural Gas Exchange Agreements [Member]
Subsidiaries [Member]
Avista Capital II [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent
U.S. federal statutory tax rate, Percent
Jointly Owned Utility Plant Expiration Year
Jointly owned utility plant expiration year.
Jointly owned utility plant expiration year
Secured and Unsecured Debt [Member]
Securedand Unsecured Debt [Member]
Secured and Unsecured Debt [Member]
Commitments and Contingencies, Policy [Policy Text Block]
Contingencies
Consolidation, Policy [Policy Text Block]
Basis of Reporting
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation
Payment of minimum tax withholdings for share-based payment awards
Alternative Revenue Programs [Member]
Alternative Revenue Programs [Member]
Alternative Revenue Programs [Member]
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Percent
Total other adjustments,Percent
Total other adjustments, Percent
Asset Class [Axis]
Asset Class
Owners percentage interest
Jointly Owned Utility Plant, Proportionate Ownership Share
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortization of Debt Issuance Costs
Amortization of debt expense
Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Noncash Item [Abstract]
Non-cash items included in net income:
Other Noncurrent Liabilities [Table Text Block]
Schedule of Other Non-Current Liabilities and Deferred Credits
Current Assets:
Assets, Current [Abstract]
Lessee operating and finance leases.
Lessee Operating And Finance Leases [Text Block]
Leases
Transportation Natural Gas [Member]
Transportation Natural Gas [Member]
Transportation Natural Gas [Member]
Leases [Abstract]
Earnings Per Share Reconciliation [Abstract]
Earnings per common share:
Document Fiscal Year Focus
Document Fiscal Year Focus
Derivative liabilities net of collateral
Energy Marketing Contract Liabilities, Current
Beginning Balance (in shares)
Common stock, shares outstanding
Common Stock, Shares, Outstanding
Ending Balance (in shares)
Wildfire Resiliency [Member]
Wildfire resiliency member.
Utility Plant Retirement Costs [Member]
Removal Costs [Member]
Financial Instruments [Domain]
Financial Instruments
Statement of Comprehensive Income [Abstract]
Measurement Input, Revenue Multiple [Member]
Revenue Market Multiples [Member]
Related Party [Member]
Affiliated Trusts [Member]
Forecast [Member]
Forecast [Member]
Public Utilities, Allowance for Funds Used During Construction, Additions
Capitalized interest
Capitalized interest
Equity Investments Issuance Price Per Share
Equity Investments Issuance Price Per Share
Equity Investments, issuance price per share
Equity investments comparable enterprise values.
Equity Investments Comparable Enterprise Values
Equity investments, comparable enterprise values
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]
Change in accounting principle accounting standards update, adopted
Operating Lease, Liability, Noncurrent
Operating lease liabilities
Schedule of Balances Outstanding and Interest Rates of Borrowings
Schedule of Line of Credit Facilities [Table Text Block]
Subsidiary, Ownership Percentage, Parent
Noncontrolling interest, ownership percentage by parent
Security Exchange Name
Security Exchange Name
Measurement Input Type [Axis]
Measurement Input Type
Revenues
Revenues
Total operating revenues
Operating revenues
Related and Nonrelated Parties [Axis]
Related Party
Entity Address, State or Province
Entity Address, State or Province
Energy Commodity Derivatives [Member]
Energy Commodity Derivatives [Member]
Energy Related Derivative [Member]
Natural and Cultural Damage Claim [Member]
Natural and Cultural Damage Claim.
Public Utilities, Policy [Policy Text Block]
Regulation
Other Electric [Member]
Other Electric [Member]
Other Electric Revenues from Contracts With Customers [Member]
Operating Lease, Right-of-Use Asset
Operating lease ROU assets
Transmission Electric [Member]
Transmission Electric [Member]
Transmission Electric [Member]
Amendment Flag
Amendment Flag
Loss Contingencies [Table]
Loss Contingencies [Table]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax
Amortization of net prior service cost
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent
Other, Percent
Revision period for emissions report.
Revision Period for Emissions report
Revision period for emissions report
Debt Instrument [Axis]
Debt Instrument
Other income-net
Other Nonoperating Income (Expense)
Other Nonoperating Income (Expense), Total
Other income-net
SOFR [Member]
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Electric Derivative [Member]
Electric Derivative [Member]
Electric Derivative [Member]
Unit Three.
Unit Three [Member]
Unit 3 [Member]
Loss Contingency Damages Claimed by Private Plaintiffs
Loss contingency damages claimed by private plaintiffs.
Damages claimed by private plaintiffs
City Area Code
City Area Code
Reported Value Measurement [Member]
Reported Value Measurement [Member]
Deferrals and Amortizations for Rate Refunds to Customers [Member]
Provision for Rate Refunds [Member]
Provisionfor Rate Refunds [Member]
Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item
Other
Entity Information, Former Legal or Registered Name
Entity Information, Former Legal or Registered Name
Deferred Compensation Plan Assets
Deferred compensation assets
Proceeds from issuance of common stock
Proceeds from Issuance of Common Stock
Issuance of common stock, net of issuance costs
Demand Side Management Programs [Member]
Demand Side Management Programs [Member]
Demand Side Management Programs [Member]
Insurance proceeds paid to their insureds [Member]
Insurance proceeds paid to their insureds [Member]
Number of residential, commercial and other structures impacted.
Number Of Residential Commercial And Other Structures Impacted
Number of residential, commercial and other structures impacted
Position
Position [Domain]
Stored natural gas
Energy Related Inventory, Gas Stored Underground
Realized and unrealized gain losses on assets
Realized and unrealized losses on assets
Realized and unrealized gain losses on assets.
Additional costs allocated percentage.
Additional costs allocated percentage
Retirement Benefits [Text Block]
Pension Plans and Other Postretirement Benefit Plans
Unamortized Debt Repurchase Costs [Member]
Unamortized Debt Repurchase Costs [Member]
Unamortized Debt Repurchase Costs [Member]
Litigation Status [Axis]
Other Operating Expenses
Other Operating Expenses
Other operating expenses
Other regulatory assets and liabilities.
Other Regulatory Assets and Liabilities
Other regulatory assets and liabilities
Notes receivable
Financing Receivable, after Allowance for Credit Loss, Current
Financing Receivable, after Allowance for Credit Loss, Current, Total
Liabilities, Current
Total current liabilities
Junior subordinated debenture issuance date
Debt Instrument Issued Date
Debt instrument issued date.
Financing Receivable, after Allowance for Credit Loss, Noncurrent, Total
Financing Receivable, after Allowance for Credit Loss, Noncurrent
Notes receivable
Regulated Asset Liability [Line Items]
Regulated Asset Liability [Line Items]
Regulated Asset Liability [Line Items]
Gas Derivative [Member]
Gas Derivative [Member]
Gas Derivative [Member]
Total
Property, Plant and Equipment, Gross, Ending Balance
Property, Plant and Equipment, Gross, Beginning Balance
Property, Plant, and Equipment, before Accumulated Depreciation, Depletion, and Amortization
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations, Total
Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation
Cash and cash equivalents at end of period
Cash and cash equivalents at beginning of period
Segment Reporting [Text Block]
Information by Business Segments
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Collaborative Arrangement and Arrangement Other than Collaborative [Axis]
Trading Symbol
Trading Symbol
Geographical [Axis]
Geographical
Effective Income Tax Rate Reconciliation, CARES Act Tax Benefit Amortization Percent
Effective Income Tax Rate Reconciliation, CARES Act Tax Benefit Amortization Percent.
CARES Act tax benefit amortization,Percent
CARES Act tax benefit amortization, Percent
Revenue from Contract with Customer, Including Assessed Tax
Revenue from contract with customer including assessed tax
Pension asset
Assets for Plan Benefits, Defined Benefit Plan
Entity Emerging Growth Company
Entity Emerging Growth Company
Schedule of Foreign Exchange Contracts, Statement of Financial Position [Table Text Block]
Summary of Foreign Currency Exchange Derivatives
Regulatory Liability [Axis]
Regulatory Liability
Derivative, Fair Value, Net
Derivative, Fair Value, Net, Total
Derivative assets net of collateral
Fair Value Measurement [Domain]
Fair Value Measurement
Long-Term Debt, Gross
Carrying amount
Decoupling Surcharge [Member]
Decoupling surcharge.
Other Liabilities, Noncurrent
Other non-current liabilities and deferred credits
Total
Issuance of notes receivable
Payments to Acquire Notes Receivable
Portion at Fair Value Measurement [Member] [Default]
Portion at Fair Value Measurement [Member]
Fair Value Disclosure Item Amounts [Default]
Finance Lease Obligation
Finance Lease, Liability, Total
Finance Lease, Liability
Finance Lease, Liability
Payments of Dividends
Cash dividends paid
Payments of Dividends, Total
Regulated Operating Revenue
Total utility revenues
Flow through related to deduction of meters and mixed service costs
Flow through related to deduction of meters and mixed service costs
Effective Income Tax Rate Reconciliation, Deduction, Amount
Effective Income Tax Rate Reconciliation, Deduction, Amount, Total
Short-Term Debt [Abstract]
Cover [Abstract]
Defined Benefit Plan, Interest Cost
Interest cost
Additional Collateral, Aggregate Fair Value
Additional collateral to post
Utilities Operating Expense, Products and Services
Resource costs
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]
Schedule of Quantitative Information
Avista Corp.
Avista Corporation [Member]
Avista Corp [Member]
Total
Public Utilities, Property, Plant and Equipment, Net
Net utility property
Equity Funds [Member]
Equity Investments [Member]
Equity Funds [Member]
Revenue from Contract with Customer [Abstract]
Long-Term Debt, Type [Domain]
Long-term Debt, Type
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total
Accumulated Other Comprehensive Income (Loss), Net of Tax
Accumulated other comprehensive loss
Schedule of Other Current Assets [Table Text Block]
Schedule of Other Current Assets
Number of Foreign Currency Derivatives Held
Number of contracts
Babb road fire.
Babb Road Fire [Member]
Share-Based Payment Arrangement, Noncash Expense
Stock-based compensation expense
Share-based Payment Arrangement, Noncash Expense, Total
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]
Schedule of Activity For Energy Commodity Derivative Assets (Liabilities) Measured At Fair Value Using Significant Unobservable Inputs (Level 3)
System Unit Resource Protection Act [Member]
System Unit Resource Protection Act.
Fair Value Disclosures [Abstract]
Cash and Cash Equivalents, at Carrying Value, Ending Balance
Cash and Cash Equivalents, at Carrying Value, Beginning Balance
Cash and Cash Equivalents, at Carrying Value, Total
Cash and Cash Equivalent
Cash and cash equivalents
Equity investments time to liquidity event.
Equity Investments Time To Liquidity Event
Equity investments, time to liquidity event
Reclassification out of Accumulated Other Comprehensive Income [Table]
Reclassification Out Of Accumulated Other Comprehensive Income [Table]
Numerator.
Numerator [Abstract]
Numerator:
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans Net Unamortized (Gain) Loss, Tax
Accumulated Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Tax
Accumulated other comprehensive income (loss), pension and other postretirement benefit plans net unamortized (gain) loss, tax
Cash Provided by (Used in) Financing Activity, Including Discontinued Operation
Net cash provided by financing activities
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Ending Balance
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value, Beginning Balance
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value
Ending Balance
Beginning Balance
Public Utility Operating Expenses Excise Taxes Collected and Reported Gross in Revenues and Operating Expenses
Public Utility Operating Expenses Excise Taxes Collected
Utility-related taxes
Interest Rate Swap [Member]
Interest Rate Swap [Member]
Collective bargaining agreements.
Collective Bargaining Agreements [Member]
Collective Bargaining Agreements [Member]
Number of Settle the Claims
Number of Settle the Claims
Number of settle the claims
Entity Filer Category
Entity Filer Category
Debt Instrument, Name [Domain]
Debt Instrument, Name
Avista.
Avista [Member]
Loss Contingency Noneconomic Damages
Loss contingency noneconomic damages.
Noneconomic damages
Lease Contractual Term [Axis]
Increase (Decrease) in Income Taxes Receivable
Income taxes receivable
Colstrip [Member]
Colstrip [Member]
Revenue from contracts with customers
Revenue from Contract with Customer, Excluding Assessed Tax
Derivative Liability, Fair Value, Gross Liability, Total
Derivative Liability, Subject to Master Netting Arrangement, before Offset
Liability
Gross Liability
Derivative Asset, Statement of Financial Position [Extensible Enumeration]
Other Postretirement Benefits Plan [Member]
Other Postretirement Benefits [Member]
Segment Reporting [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
Summary of Significant Factors Impact on Difference Between Effective Tax Rate and Federal Statutory Rate
Regulatory Liabilities, Non-Current
Regulatory Liability, Noncurrent
Regulatory Liability, Noncurrent, Total
Non-current regulatory liabilities
Other Assets, Current
Other current assets
Total
Entity Address, Postal Zip Code
Entity Address, Postal Zip Code
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings
Recognized in net income
Statement of Financial Position [Abstract]
Regulated revenues, excluding alternative revenue programs
Regulated Revenues Excluding Alternative Revenue Programs
Utility revenues, exclusive of alternative revenue programs
Local Phone Number
Local Phone Number
President and Chief Executive Officer [Member]
President and Chief Executive Officer.