75000 - Document - Document and Entity Information link:presentationLink link:calculationLink link:definitionLink 75010 - Statement - STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS link:presentationLink link:calculationLink link:definitionLink 75020 - Statement - STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS link:presentationLink link:calculationLink link:definitionLink 75030 - Disclosure - Description of the Plan link:presentationLink link:calculationLink link:definitionLink 75040 - Disclosure - Summary of Significant Accounting Policies link:presentationLink link:calculationLink link:definitionLink 75050 - Disclosure - Fair Value of Measurements link:presentationLink link:calculationLink link:definitionLink 75060 - Disclosure - Investments link:presentationLink link:calculationLink link:definitionLink 75070 - Disclosure - Risks and Uncertainties link:presentationLink link:calculationLink link:definitionLink 75080 - Disclosure - Plan Termination link:presentationLink link:calculationLink link:definitionLink 75090 - Disclosure - Plan Tax Status link:presentationLink link:calculationLink link:definitionLink 75100 - Disclosure - Party-in-Interest Transactions link:presentationLink link:calculationLink link:definitionLink 75110 - Disclosure - Schedule of Assets (Held at End of Year) link:presentationLink link:calculationLink link:definitionLink 75120 - Disclosure - Summary of Significant Accounting Policies (Policies) link:presentationLink link:calculationLink link:definitionLink 75130 - Disclosure - Description of the Plan (Tables) link:presentationLink link:calculationLink link:definitionLink 75140 - Disclosure - Fair Value of Measurements (Tables) link:presentationLink link:calculationLink link:definitionLink 75150 - Disclosure - Description of the Plan - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75160 - Disclosure - Description of the Plan - Summary of Percentage of Compensation the Company Contributes (Details) link:presentationLink link:calculationLink link:definitionLink 75170 - Disclosure - Fair Value Measurements - Summary of Fair Value of Plan Assets by Level within Fair Value Hierarchy (Details) link:presentationLink link:calculationLink link:definitionLink 75180 - Disclosure - Investments - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75190 - Disclosure - Plan Termination - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75200 - Disclosure - Plan Tax Status - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75210 - Disclosure - Party-in-Interest Transactions - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75220 - Disclosure - Schedule H, Line 4i - Schedule of Assets (Held at End of Year) (Details) link:presentationLink link:calculationLink link:definitionLink 75220 - Disclosure - Schedule H, Line 4i - Schedule of Assets (Held at End of Year) (Details) [Default] link:presentationLink link:calculationLink link:definitionLink 999009 - Disclosure - Anchoring link:presentationLink link:calculationLink link:definitionLink EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Employee benefit plan, note receivable from participant, account, maximum borrowing, to total account, percentage EBP, Forfeited Nonvested Account, Decrease from Employer Contribution Employee benefit plan forfeited balance used to reduce Company contribution EBP, Subsequent Event [Policy Text Block] Subsequent Events EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Fees Administrative Expenses EBP, Net Asset Available for Benefit Net assets available for benefits from the financial statements Beginning of Year End of Year Net Assets Available for Benefits Minimum [Member] Minimum EBP, Employer Contribution, Matching Percentage Matching contribution percentage Percentage of participants contribution EBP, Net Asset Available for Benefit [Abstract] Net Assets Available for Benefits EBP, Schedule of Asset Held for Investment [Table] EBP, Tax Status [Line Items] EBP, Payment to Participant [Policy Text Block] Benefit Payments EBP, Expense [Policy Text Block] Administrative Expenses Employee Benefit Plan Notes Receivable From Participants General Loan Term Employee benefit plan notes receivable from participants general loan term. Employee benefit plan, notes receivable from participants general loan EBP, Description of Plan and Accounting Change [Abstract] Employee benefit plan vested percentage. Employee Benefit Plan Vested Percentage Vesting percentage EBP, Fully Benefit-Responsive Investment Contract [Table] Employee Benefit Plan Share Price Per Share of Common Stock Employee benefit plan share price per share of common stock. Share price per share EBP, Net Asset Value per Share or Unit Net asset price per share Document Period End Date Document Information [Table] EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Current Value EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] Fifty or Older Age [Member] Fifty or older age. 50 or Older Investments [Domain] EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Employer Contribution, Receivable Employer Contributions Employee Benefit Plan Number of Employees Hired Employee benefit plan number of employees hired. Employee benefit plan, number of employees hired EBP, Investment, Fair Value EBP, Investment, Fair Value, Total Investments fair value EBP, Self-Directed Brokerage Account [Member] Self-Directed Securities EBP, Note Receivable from Participant Notes receivable from participants Investments EBP, Fully Benefit-Responsive Investment Contract [Text Block] EBP, Tax Status [Text Block] Plan Tax Status Seventy Five Percent Employee Contributions [Member] Seventy five percent employee contributions. 75% Employee Contributions EBP, Use of Estimate [Policy Text Block] Use of Estimates EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash and Noncash EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash and Noncash, Total Employer EBP, Investment, Employer, Common Stock, to Total Asset, Percentage Plan investments in the stock fund of total plan assets Investments contract value EBP, Investment, Contract Value EBP, Investment, Contract Value, Total EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Investment income: EBP, Accounting Policy [Table] EBP, Investment [Policy Text Block] Investment Valuation and Income Recognition Common Collective Trust [Member] Common collective trust funds Collective Trust EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Interest Income on Notes Receivable from Participants Statistical Measurement [Axis] EBP, Employer Contribution, Participant Compensation Matched, Percentage Percentage on employee eligible compensation Contribution percentage EBP, Basis of Accounting [Policy Text Block] Basis of Accounting Younger Than Forty Age [Member] Younger than forty age. Younger than 40 Fair Value, Inputs, Level 3 [Member] Level 3 EBP, Investment, Fair Value and NAV [Table Text Block] Summary of Fair Value of Plan Assets by Level within Fair Value Hierarchy EBP, Tax Qualification Status [Extensible Enumeration] EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan Net appreciation in fair value of Plan assets EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Notes receivable from participants Employees Hired Prior to January One Two Thousand Six [Member] Employees hired prior to january one two thousand six. Employees Hired Prior to January 1, 2006 Plan Participants Hired On or After April One Two Thousand Twenty Two [Member] Plan participants hired on or after april one two thousand twenty two. Plan Participants Hired on or After April 1, 2022 Fair Value Hierarchy and NAV [Axis] EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Deductions: EBP, Investment, Purchased, Number of Shares Number of shares purchased Employee Benefit Plan Non Elective Employer Contribution Participant Compensation Matched Vesting Percentage Employee benefit plan, non-elective employer contribution, participant compensation matched, vesting percentage. Employee benefit plan, non-elective employer contribution, participant compensation matched, vesting percentage Employees Hired on or After January One Two Thousand Eleven [Member] Employees hired on or after january one two thousand eleven. Employees Hired on or After January 1, 2011 EBP, Description of Plan [Line Items] EBP, Risk and Uncertainty [Abstract] EBP, Change in Net Asset Available for Benefit, Increase from Contribution Total Contributions Employee Benefit Plan Participant Loan Maturity Year Employee benefit plan participant loan maturity year. Employee benefit plan participant loan maturity year Document Fiscal Period Focus EBP, Participant Contribution, Automatic, Deferral Rate Percentage of participants contribution Employee benefit plan percentage of increase in plan participants contribution per year. Employee Benefit Plan Percentage of Increase in Plan Participants Contribution Per Year Percentage of increase in plan participants contribution per year EBP, Employer, Common Stock [Member] Common Stock EBP, Schedule of Asset Held for Investment [Abstract] EBP, Change in Net Asset Available for Benefit, Decrease Total Deductions EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Investment, Issuer Name [Extensible Enumeration] EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Employee benefit plan, notes receivable from participant, account, maximum borrowing, amount Fair Value, Inputs, Level 1 [Member] Level 1 Investment Type [Axis] Employees Hired on or After January One Two Thousand Six [Member] Employees hired on or after january one two thousand six. Employees Hired on or After January 1, 2006 EBP, Investment, Current Value, Type [Extensible Enumeration] Plan Participants Hired Prior to April One Two Thousand Twenty Two [Member] Plan participants hired prior to april one two thousand twenty two. Plan Participants Hired Prior to April 1, 2022 EBP, Risk and Uncertainty [Text Block] Risks and Uncertainties Statistical Measurement [Domain] EBP, Fully Benefit-Responsive Investment Contract [Line Items] Entity Central Index Key EBP, Asset Held for Investment, Participant Loan, Interest Rate Employee benefit plan, asset held for investment, participant loan, interest rate Employee benefit plan, interest rate EBP, Summary of Accounting Policy [Text Block] Summary of Significant Accounting Policies Current Fiscal Year End Date EBP, Participant Contribution, Pretax, Maximum Annual Compensation, Amount Employee's annual before-tax contribution limitation amount EBP, Plan Termination [Text Block] Plan Termination Fair Value, Inputs, Level 2 [Member] Level 2 Employee Benefit Plan Vested Interest Distribution Lump-sum Payment Employee benefit plan vested interest distribution lump-sum payment. Employee benefit plan vested interest distribution lump-sum payment EBP, Statement of Net Asset Available for Benefit [Table] EBP, Accounting Policy [Line Items] EBP, Investment, Fair Value and NAV [Abstract] Employee Benefit Plan Vested Interest Distribution Period Employee benefit plan vested interest distribution period. Employee benefit plan vested interest distribution period Fair Value Hierarchy and NAV [Domain] EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment, Total Interest and dividends Interest and Dividend Income Employee benefit plan notes receivable from participants interest rate of prime rate plus percentage Employee Benefit Plan Notes Receivable From Participants Interest Rate of Prime Rate Plus Percentage Employee benefit plan notes receivable from participants interest rate of prime rate plus percentage. Vanguard Fiduciary Trust Company [Member] Vanguard Fiduciary Trust Company. Vanguard Fiduciary Trust Company EBP, Related Party and Party-in-Interest Transactions [Text Block] Party-in-Interest Transactions Employee Benefit Plan Employer Contribution Participant Compensation Matched Vesting Percentage Employee benefit plan, employer contribution, participant compensation matched, vesting percentage. Employee benefit plan, employer contribution, participant compensation matched, vesting percentage EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Net increase in net assets available for benefits per the financial statements INCREASE IN NET ASSETS Net Increase EBP, Asset [Abstract] ASSETS Assets: EBP, Investment, Fair and Contract Value [Abstract] Investment in Plan Trust: Investments (at Fair Value): Document Type EBP, Description of Plan [Table] EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover Employee EBP, Statement of Change in Net Asset Available for Benefit [Abstract] EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment, Total Net Appreciation in Fair Value of Investments Employees Hired on or After January One Two Thousand Fourteen [Member] Employees hired on or after january one two thousand fourteen. Employees Hired on or After January 1, 2014 Employee benefit plan termination participants employer contributions vested percentage Employee Benefit Plan Termination Participants Employer Contributions Vested Percentage Employee benefit plan termination participants employer contributions vested percentage Entity Registrant Name EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment Employee benefit plan, Dividends received EBP, Description of Plan [Text Block] Description of the Plan Employees Hired Prior to January One Two Thousand Eleven [Member] Employees hired prior to January one two thousand eleven. Employees Hired Prior to January 1, 2011 EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] EBP, Risk and Uncertainty [Line Items] Members Hired on or After January One Two Thousand Twenty Four [Member] Members hired on or after january one, two thousand twenty four. Members Hired on or After January 1, 2024 EBP, Tax Determination Letter, Date Tax determination letter, date EBP, Plan Number EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment Plan interest in BNSF 401(k) Plans Master Trust investment income (Note 4) Total Investment Income EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value, Ending Balance EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value, Beginning Balance Investment at fair value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value, Total Total Investments at Fair Value Total Investments (at Fair Value) EBP, Tax Status [Abstract] Employee Benefit Plan Investment TextBlock Employee benefit plan investment. Investments Employee Benefit Plan Participant Contribution Pretax Minimum Annual Compensation To Total Compensation Percentage Employee benefit plan participant contribution pretax minimum annual compensation to total compensation percentage. Percentage of before-tax contributions of eligible compensation Mutual Fund [Member] Mutual Funds EBP, Noninterest-Bearing Cash Stock Fund held in cash EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Fees paid to Individual participant Benefits Paid to Participants EBP, Receivable Total Receivables EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Forfeited Nonvested Account Employee benefit plan, unused forfeited balances Employee Benefit Plan Participant Consent Required for Vested Interest Distribution Employee benefit plan participant consent required for vested interest distribution. Employee benefit plan participant consent required for vested interest distribution Entity Tax Identification Number EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount Employee benefit plan, notes receivable from participant, minimum loan, amount EBP, Note Receivable from Participant [Policy Text Block] Notes Receivable From Participants Entity [Domain] Hundred Percent Employee Contributions [Member] Hundred percent employee contributions. 100% Employee Contributions EBP, Schedule of Asset Held for Investment [Table Text Block] Schedule of Assets (Held at End of Year) EBP, Related Party and Party-in-Interest [Axis] EBP, Related Party and Party-in-Interest Transactions [Line Items] Maximum [Member] Maximum Employee Benefit Plan Number of Non-Local Employees Employee benefit plan number of non-local employees. Employee benefit plan number of non-local employees Employees Hired on or After April One Two Thousand Fourteen [Member] Employees hired on or after april one, two thousand fourteen. Employees Hired on or After April 1, 2014 Employees Hired on or After April One Two Thousand Seventeen [Member] Employees hired on or after april one two thousand seventeen. Employees Hired on or after April 1, 2017 EBP, Investment, Fair Value and NAV [Text Block] Fair Value Measurements Document Fiscal Year Focus EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage Percentage of before-tax contributions of eligible compensation EBP, Employer, Common Stock Fund [Member] Avista Corp. Company Stock Fund EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Contributions: EBP, Fully Benefit-Responsive Investment Contract [Abstract] Forty to Forty Nine Age [Member] Forty to forty nine age. 40-49 EBP, Contribution [Table Text Block] Summary of Percentage of Compensation the Company Contributes Amendment Flag Employee Benefit Plan Notes Receivable From Participants Primary Residence Loan Term Employee benefit plan notes receivable from participants primary residence loan term. Employee benefit plan, notes receivable from participants primary residence loan term Employee Benefit Plan Number of Local Employees Employee benefit plan number of local employees. Employee benefit plan number of local employees EBP, Tax Determination Letter, Obtained [true false] Tax determination letter, obtained EBP, Tax Status [Table] Employee Benefit Plan, IBEW Chapter Employee benefit plan, IBEW chapter. Employee benefit plan, IBEW chapter Investment, Identifier [Axis] EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Rollover EBP, Receivable [Abstract] Receivables: EBP, employer contribution, participant compensation percentage. EBP, Employer Contribution, Participant Compensation Percentage Contribution percentage Employer non-elective contribution of eligible compensation EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Master Trust [Table] Legal Entity [Axis] EBP, Asset Held for Investment, Party-in-Interest [true false] EBP 003 EBP 003 [Member] EBP 003 Cover [Abstract] EBP, Asset Held for Investment Total assets held for investment purposes EBP, Contribution, Participating Employer [Domain] Employee Benefit Plan Vested Interest Distribution Monthly Installments Period Employee benefit plan vested interest distribution monthly installments period. Employee benefit plan vested interest distribution monthly installments period EBP, Investment, Fair Value and NAV [Table] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Contribution, Participating Employer [Axis] EBP, Risk and Uncertainty [Table] EBP, Investment, Fair Value and NAV [Line Items] EBP, Related Party and Party-in-Interest [Domain] EBP, Statement of Change in Net Asset Available for Benefit [Table] Document Information [Line Items] EBP, Master Trust [Line Items] Employee benefit plan participant contribution vesting description. Employee Benefit Plan Participant Contribution Vesting Description Employee benefit plan contribution vesting description Vanguard Sm-Cap Growth Index Baird Core Plus Bond Fund Instl Class [Member] Baird Core Plus Bond Fund Instl Class Self-Directed Brokerage Fund [Member] Vanguard Wellington Fund Admiral Shares Vanguard Target Ret Income & Growth Trust II Avista Corporation [Member] Vanguard Retirement Savings Trust III Vanguard Target Ret 2060 Trust II [Member] Vanguard Federal Money Market Fund [Member] Vanguard Institutional Index Fund Vanguard Infla-Prot Securities [Member] Victory Sycamore Sm Co Opportunity Fd R6 Vanguard Target Ret 2045 Trust II Victory Sycamore Sm Co Opportunity Fd R6 [Member] Vanguard Federal Money Market Fund T. Rowe Price QM US Sm-Cap Grwth Eqty Fd I Vanguard Total Int'l Stock Idx Vanguard Infla-Prot Securities Vanguard Target Ret 2060 Trust II Vanguard Total Bd Mkt Indx Inv Vanguard Target Ret 2065 Trust II [Member] Vanguard Total Int'l Stock Idx [Member] Vanguard Target Ret 2050 Trust II [Member] Vanguard Target Ret 2035 Trust II [Member] Vanguard Retirement Savings Trust III [Member] Vanguard Target Ret 2030 Trust II [Member] Vanguard Target Ret 2040 Trust II [Member] Vanguard Target Ret 2070 Trust II [Member] Vanguard Mid-Cap Index Fund Instl Shares Avista Corp [Member] Vanguard Intl Growth Fund Admiral Shares Transamerica International Equity R6 Vanguard Wellington Fund Admiral Shares [Member] Vanguard Target Ret 2045 Trust II [Member] Transamerica International Equity R6 [Member] T. Rowe Price QM US Sm-Cap Grwth Eqty Fd I [Member] MFS Growth Fund Class R6 Vanguard Target Ret Income & Growth Trust II [Member] Vanguard Target Ret Income Trust II Vanguard Target Ret 2035 Trust II Vanguard Target Ret 2030 Trust II Vanguard Target Ret 2050 Trust II Vanguard Total Bd Mkt Indx Inv [Member] Vanguard Sm-Cap Growth Index [Member] Vanguard Target Ret 2025 Trust II [Member] Vanguard Institutional Index Fund [Member] Vanguard Target Ret 2070 Trust II Vanguard Sm-Cap Value Index Vanguard Target Ret 2020 Trust II Vanguard Intl Growth Fund Admiral Shares [Member] T. Rowe Price Inst'l Large Cap Value Fd C [Member] MFS Growth Fund Class R6 [Member] Vanguard Target Ret 2025 Trust II Vanguard Mid-Cap Index Fund Instl Shares [Member] Avista Corp. Self-Directed Brokerage Fund Vanguard Target Ret 2055 Trust II T. Rowe Price Inst'l Large Cap Value Fd C Vanguard Target Ret 2040 Trust II Vanguard Target Ret 2020 Trust II [Member] Vanguard Target Ret 2065 Trust II Vanguard Target Ret Income Trust II [Member] Vanguard Target Ret 2055 Trust II [Member] Vanguard Sm-Cap Value Index [Member]