Avista (AVA) 10-K 21 Feb 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2022	Jan. 31, 2023	Jun. 30, 2022
Cover [Abstract]
Entity Registrant Name	AVISTA CORPORATION
Amendment Flag	false
Document Transition Report	false
Document Annual Report	true
Document Type	10-K
Document Period End Date	Dec. 31, 2022
Entity File Number	001-03701
Entity Tax Identification Number	91-0462470
Entity Incorporation, State or Country Code	WA
Entity Address, Address Line One	1411 East Mission Avenue
Entity Address, City or Town	Spokane
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	99202-2600
City Area Code	509
Local Phone Number	489-0500
Title of 12(b) Security	Common Stock
Trading Symbol	AVA
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 3,175,189,328
Entity Common Stock, Shares Outstanding		75,030,135
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Central Index Key	0000104918
Current Fiscal Year End Date	--12-31
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	Documents Incorporated By Reference Document Part of Form 10-K into Which Document is Incorporated Proxy Statement to be filed in connection with the annual meeting of shareholders to be held on May 11, 2023. Prior to such filing, the Proxy Statement was filed in connection with the annual meeting of shareholders held on May 12, 2022. Part III, Items 10, 11, 12, 13 and 14
Auditor Name	Deloitte & Touche LLP
Auditor Location	Portland, Oregon
Auditor Firm ID	34

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Utility revenues:
Utility revenues, exclusive of alternative revenue programs	$ 1,742,876	$ 1,445,000	$ 1,324,091
Alternative revenue programs	(33,357)	(6,635)	(3,814)
Total utility revenues	1,709,519	1,438,365	1,320,277
Non-utility revenues	688	571	1,614
Total operating revenues	1,710,207	1,438,936	1,321,891
Utility operating expenses:
Resource costs	735,862	497,123	398,509
Other operating expenses	405,165	366,125	354,614
Depreciation and amortization	253,017	231,915	223,507
Taxes other than income taxes	114,193	109,353	106,501
Non-utility operating expenses:
Other operating expenses	11,603	5,927	5,344
Depreciation and amortization	125	261	716
Total operating expenses	1,519,965	1,210,704	1,089,191
Income from operations	190,242	228,232	232,700
Interest expense	117,634	105,731	104,348
Interest expense to affiliated trusts	1,058	421	713
Capitalized interest	(3,718)	(3,987)	(4,083)
Other income-net	(62,717)	(33,298)	(4,817)
Income before income taxes	137,985	159,365	136,539
Income tax expense (benefit)	(17,191)	12,031	7,051
Net income	$ 155,176	$ 147,334	$ 129,488
Weighted-average common shares outstanding (thousands), basic	72,989	69,951	67,962
Weighted-average common shares outstanding (thousands), diluted	73,093	70,085	68,102
Earnings per common share:
Basic	$ 2.13	$ 2.11	$ 1.91
Diluted	$ 2.12	$ 2.10	$ 1.90

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 155,176	$ 147,334	$ 129,488
Other Comprehensive Income (Loss):
Change in unfunded benefit obligation for pension and other postretirement benefit plans - net of taxes of $2,387, $888 and $(1,095), respectively	8,981	3,339	(4,119)
Total other comprehensive income (loss)	8,981	3,339	(4,119)
Comprehensive income	$ 164,157	$ 150,673	$ 125,369

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Defined Benefit Plan, after Reclassification Adjustment, Tax	$ 2,387	$ 888	$ (1,095)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current Assets:
Cash and cash equivalents	$ 13,428	$ 22,168
Accounts and notes receivable, net	255,746	203,035
Materials and supplies, fuel stock and stored natural gas	107,674	84,733
Regulatory assets	193,787	43,783
Other current assets	151,167	80,754
Total current assets	721,802	434,473
Net utility property	5,444,709	5,225,515
Goodwill	52,426	52,426
Non-current regulatory assets	833,328	860,626
Other property and investments-net and other non-current assets	365,085	280,543
Total assets	7,417,350	6,853,583
Current Liabilities:
Accounts payable	202,954	133,096
Current portion of long-term debt	13,500	250,000
Short-term borrowings	463,000	284,000
Regulatory liabilities	95,665	77,149
Other current liabilities	189,415	168,861
Total current liabilities	964,534	913,106
Long-term debt	2,281,013	1,898,370
Long-term debt to affiliated trusts	51,547	51,547
Pensions and other postretirement benefits	93,901	153,467
Deferred income taxes	674,995	642,709
Non-current regulatory liabilities	840,837	861,515
Other non-current liabilities and deferred credits	175,855	178,125
Total liabilities	5,082,682	4,698,839
Commitments and Contingencies (See Notes to Consolidated Financial Statements)
Avista Corporation Shareholders’ Equity:
Common stock, no par value; 200,000,000 shares authorized; 74,945,948 and 71,497,523 shares issued and outstanding, respectively	1,525,185	1,380,152
Accumulated other comprehensive loss	(2,058)	(11,039)
Retained earnings	811,541	785,631
Total equity	2,334,668	2,154,744
Total liabilities and equity	$ 7,417,350	$ 6,853,583

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares, issued	74,945,948	71,497,523
Common stock, shares outstanding	74,945,948	71,497,523

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Activities:
Net income	$ 155,176	$ 147,334	$ 129,488
Non-cash items included in net income:
Depreciation and amortization	253,142	232,176	224,223
Provision for deferred income taxes	(18,231)	11,224	44,964
Power and natural gas cost amortizations (deferrals), net	(78,350)	(51,847)	(9,923)
Amortization of debt expense	1,974	2,606	3,237
Stock-based compensation expense	8,717	4,713	5,846
Equity-related AFUDC	(6,704)	(7,004)	(6,970)
Pension and other postretirement benefit expense	32,173	29,077	33,812
Other regulatory assets and liabilities and deferred debits and credits	(20,409)	676	10,287
Change in decoupling regulatory deferral	33,469	6,056	2,971
Realized and unrealized gains on assets and investments	(50,006)	(23,187)	(5,170)
Other	11,957	(2,859)	2,373
Contributions to defined benefit pension plan	(42,000)	(42,000)	(22,000)
Cash paid on settlement of interest rate swap agreements	(17,035)	(17,568)	(33,499)
Cash received on settlement of interest rate swap agreements		324
Changes in certain current assets and liabilities:
Accounts and notes receivable	(56,007)	(46,107)	(10,960)
Materials and supplies, fuel stock and stored natural gas	(22,941)	(17,282)	(868)
Collateral posted for derivative instruments	(141,014)	(17,564)	1,579
Income taxes receivable	(1,125)	20,199	(41,363)
Other current assets	(6,613)	930	(2,401)
Accounts payable	65,928	33,369	(10,152)
Other current liabilities	22,106	4,074	15,530
Net cash provided by operating activities	124,207	267,340	331,004
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(451,995)	(439,939)	(404,306)
Issuance of notes receivable	(2,745)	(1,841)	(4,393)
Equity and property investments	(10,642)	(16,001)	(5,925)
Proceeds from sale of investments	1,000	8,306	6,786
Other	4,144	4,559	(2,905)
Net cash used in investing activities	(460,238)	(444,916)	(410,743)
Financing Activities:
Net increase (decrease) in short-term borrowings	179,000	81,000	17,200
Proceeds from issuance of long-term debt	399,856	140,000	165,000
Maturity of long-term debt and finance leases	(253,085)	(2,935)	(54,800)
Issuance of common stock, net of issuance costs	137,778	89,998	72,200
Cash dividends paid	(129,061)	(118,211)	(110,254)
Other	(7,197)	(4,304)	(5,307)
Net cash provided by financing activities	327,291	185,548	84,039
Net increase (decrease) in cash and cash equivalents	(8,740)	7,972	4,300
Cash and cash equivalents at beginning of year	22,168	14,196	9,896
Cash and cash equivalents at end of year	13,428	22,168	14,196
Cash paid (received) during the year:
Interest	107,468	98,592	97,717
Income taxes paid	2,251	3,652	1,901
Income tax refunds	(86)	(22,330)	(918)
Non-cash financing and investing activities:
Accounts payable for capital expenditures	$ 27,708	$ 23,938	$ 32,039

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2019		$ 1,210,741	$ (10,259)	$ 738,802
Beginning Balance (in shares) at Dec. 31, 2019		67,176,996
Issuance of common stock through equity compensation plans		$ 965
Shares issued through equity compensation plans		139,726
Issuance of common stock through Employee Investment Plan		$ 674
Shares issued through Employee Investment Plan		17,179
Issuance of common stock through sales agency agreements, net of issuance costs		$ 70,561
Shares issued through sales agency agreements		1,905,000
Equity compensation expense		$ 5,535
Payment of minimum tax withholdings for share-based payment awards		(2,408)
Other comprehensive income (loss)	$ (4,119)		(4,119)
Net income	129,488			129,488
Dividends on common stock				(110,254)
Ending Balance at Dec. 31, 2020	$ 2,029,726	$ 1,286,068	(14,378)	758,036
Ending Balance (in shares) at Dec. 31, 2020		69,238,901
Dividends declared per common share	$ 1.62
Issuance of common stock through equity compensation plans		$ 931
Shares issued through equity compensation plans		93,806
Issuance of common stock through Employee Investment Plan		$ 610
Shares issued through Employee Investment Plan		14,480
Issuance of common stock through sales agency agreements, net of issuance costs		$ 88,457
Shares issued through sales agency agreements		2,150,336
Equity compensation expense		$ 5,079
Payment of minimum tax withholdings for share-based payment awards		(993)
Other comprehensive income (loss)	$ 3,339		3,339
Net income	147,334			147,334
Dividends on common stock				(119,739)
Ending Balance at Dec. 31, 2021	$ 2,154,744	$ 1,380,152	(11,039)	785,631
Ending Balance (in shares) at Dec. 31, 2021	71,497,523	71,497,523
Dividends declared per common share	$ 1.69
Issuance of common stock through equity compensation plans		$ 1,150
Shares issued through equity compensation plans		123,631
Issuance of common stock through Employee Investment Plan		$ 605
Shares issued through Employee Investment Plan		14,306
Issuance of common stock through sales agency agreements, net of issuance costs		$ 137,173
Shares issued through sales agency agreements		3,310,488
Equity compensation expense		$ 7,567
Payment of minimum tax withholdings for share-based payment awards		(1,462)
Other comprehensive income (loss)	$ 8,981		8,981
Net income	155,176			155,176
Dividends on common stock				(129,266)
Ending Balance at Dec. 31, 2022	$ 2,334,668	$ 1,525,185	$ (2,058)	$ 811,541
Ending Balance (in shares) at Dec. 31, 2022	74,945,948	74,945,948
Dividends declared per common share	$ 1.76

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE 1. SUMMARY OF SIGNIF ICANT ACCOUNTING POLICIES Nature of Business Avista Corp. is primarily an electric and natural gas utility with certain other business ventures. Avista Utilities is an operating division of Avista Corp., comprising its regulated utility operations in the Pacific Northwest. Avista Utilities provides electric distribution and transmission, and natural gas distribution services in parts of eastern Washington and northern Idaho. Avista Utilities also provides natural gas distribution service in parts of northeastern and southwestern Oregon. Avista Utilities has electric generating facilities in Washington, Idaho, Oregon and Montana. Avista Utilities also supplies electricity to a small number of customers in Montana, most of whom are employees who operate the Company's Noxon Rapids generating facility. AERC is a wholly-owned subsidiary of Avista Corp. The primary subsidiary of AERC is AEL&P, which comprises Avista Corp.'s regulated utility operations in Alaska. Avista Capital, a wholly owned non-regulated subsidiary of Avista Corp., is the parent company of all of the subsidiary companies in the non-utility businesses, with the exception of AJT Mining Properties, Inc., which is a subsidiary of AERC. See Note 24 for business segment information. Basis of Reporting The consolidated financial statements include the assets, liabilities, revenues and expenses of the Company and its subsidiaries and other majority owned subsidiaries and variable interest entities for which the Company or its subsidiaries are the primary beneficiaries. Intercompany balances were eliminated in consolidation. The accompanying consolidated financial statements include the Company’s proportionate share of utility plant and related operations resulting from its interests in jointly owned plants (see Note 9 ). Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported for assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates include: • determining the market value of energy commodity derivative assets and liabilities, • pension and other postretirement benefit plan obligations, • contingent liabilities, • goodwill impairment testing, • fair value of equity investments, • recoverability of regulatory assets, and • unbilled revenues. Changes in these estimates and assumptions are considered reasonably possible and may have a material effect on the consolidated financial statements and thus actual results could differ from the amounts reported and disclosed herein. Regulation The Company is subject to state regulation in Washington, Idaho, Montana, Oregon and Alaska. The Company is also subject to federal regulation primarily by the FERC, as well as various other federal agencies with regulatory oversight of particular aspects of its operations. Depreciation For utility operations, depreciation expense is estimated by a method of depreciation accounting utilizing composite rates for utility plant. Such rates are designed to provide for retirements of properties at the expiration of their service lives. For utility operations, the ratio of depreciation provisions to average depreciable property was as follows for the years ended December 31: 2022 2021 2020 Avista Utilities Ratio of depreciation to average depreciable property 3.50 % 3.54 % 3.43 % Alaska Electric Light and Power Company Ratio of depreciation to average depreciable property 2.78 % 2.77 % 2.77 % The average service lives for the following broad categories of utility plant in service are (in years): Avista Utilities Alaska Electric Light Electric thermal/other production 26 41 Hydroelectric production 79 42 Electric transmission 50 43 Electric distribution 39 39 Natural gas distribution property 44 N/A Other shorter-lived general plant 8 19 Allowance for Funds Used During Construction AFUDC represents the cost of both the debt and equity funds used to finance utility plant additions during the construction period. As prescribed by regulatory authorities, AFUDC is capitalized as a part of the cost of utility plant. The debt component of AFUDC is credited against total interest expense in the Consolidated Statements of Income in the line item “capitalized interest.” The equity component of AFUDC is included in the Consolidated Statements of Income in the line item “other income-net.” The Company is permitted, under established regulatory rate practices, to recover the capitalized AFUDC, and a reasonable return thereon, through its inclusion in rate base and the provision for depreciation after the related utility plant is placed in service. Cash inflow related to AFUDC does not occur until the related utility plant is placed in service and included in rate base. The WUTC and IPUC have authorized Avista Utilities to calculate AFUDC using its allowed rate of return. To the extent amounts calculated using this rate exceed the AFUDC amounts calculated using the FERC formula, Avista Utilities capitalizes the excess as a regulatory asset. The regulatory asset associated with plant in service is amortized over the average useful life of Avista Utilities' utility plant which is approximately 30 years. The regulatory asset associated with construction work in progress is not amortized until the plant is placed in service. The effective AFUDC rate was the following for the years ended December 31: 2022 2021 2020 Avista Utilities 7.12 % 7.19 % 7.25 % Alaska Electric Light and Power Company 8.08 % 8.90 % 8.04 % Income Taxes Deferred income tax assets represent future income tax deductions the Company expects to utilize in future tax returns to reduce taxable income. Deferred income tax liabilities represent future taxable income the Company expects to recognize in future tax returns. Deferred tax assets and liabilities arise when there are temporary differences resulting from differing treatment of items for tax and accounting purposes. A deferred income tax asset or liability is determined based on the enacted tax rates that will be in effect when the temporary differences between the financial statement carrying amounts and tax basis of existing assets and liabilities are expected to be reported in the Company’s consolidated income tax returns. The effect on deferred income taxes from a change in tax rates is recognized in income in the period that includes the enactment date unless a regulatory order specifies deferral of the effect of the change in tax rates over a longer period of time. The Company establishes a valuation allowance when it is more likely than not that all, or a portion, of a deferred tax asset will not be realized. Deferred income tax assets and liabilities and regulatory assets and liabilities are established for income tax benefits flowed through to customers. The Company's largest deferred income tax item is the difference between the book and tax basis of utility plant. This item results from the temporary difference on depreciation expense. In early tax years, this item is recorded as a deferred income tax liability that will eventually reverse and become subject to income tax in later tax years. The Company did no t incur any penalties on income tax positions in 2022, 2021 or 2020 . The Company would recognize interest accrued related to income tax positions as interest expense and any penalties incurred as other operating expense. Stock-Based Compensation The Company currently issues three types of stock-based compensation awards - restricted shares, market-based awards and performance-based awards. Historically, these stock compensation awards have not been material to the Company's overall financial results. Compensation cost relating to share-based payment transactions is recognized in the Company’s financial statements based on the fair value of the equity instruments issued and recorded over the requisite service period. The Company recorded stock-based compensation expense (included in other operating expenses) and income tax benefits in the Consolidated Statements of Income of the following amounts for the years ended December 31 (dollars in thousands): 2022 2021 2020 Stock-based compensation expense $ 7,567 $ 4,713 $ 5,846 Income tax benefits 1,589 990 1,228 Excess tax expenses on settled share-based employee ( 19 ) ( 909 ) ( 165 ) Restricted share awards vest in equal thirds each year over 3 years and are payable in Avista Corp. common stock at the end of each year if the service condition is met. Restricted stock is valued at the close of market of the Company’s common stock on the grant date. Total Shareholder Return (TSR) awards are market-based awards and Cumulative Earnings Per Share (CEPS) awards are performance awards. Both types of awards vest after a period of 3 years and are payable in cash or Avista Corp. common stock at the end of the three-year period. The method of settlement is at the discretion of the Company and historically the Company has settled these awards through issuance of Avista Corp. common stock and intends to continue this practice. Both types of awards entitle the recipients to dividend equivalent rights, are subject to forfeiture under certain circumstances, and are subject to meeting specific market or performance conditions. Based on the level of attainment of the market or performance conditions, the amount of cash paid or common stock issued will range from 0 to 200 percent of the initial awards granted. Dividend equivalent rights are accumulated and paid out only on shares that eventually vest and have met the market and performance conditions. The Company accounts for both the TSR awards and CEPS awards as equity awards and compensation cost for these awards is recognized over the requisite service period, provided that the requisite service period is rendered. For TSR awards, if the market condition is not met at the end of the three-year service period, there will be no change in the cumulative amount of compensation cost recognized, since the awards are still considered vested even though the market metric was not met. For CEPS awards, at the end of the three-year service period, if the internal performance metric of cumulative earnings per share is not met, all compensation cost for these awards is reversed as these awards are not considered vested. The fair value of each TSR award is estimated on the date of grant using a statistical model that incorporates the probability of meeting the market targets based on historical returns relative to a peer group. The estimated fair value of the CEPS awards was estimated on the date of grant as the share price of Avista Corp. common stock on the date of grant. The following table summarizes the number of grants, vested and unvested shares, earned shares (based on market metrics), and other pertinent information related to the Company's stock compensation awards for the years ended December 31: 2022 2021 2020 Restricted Shares Shares granted during the year 115,746 62,594 45,540 Shares vested during the year 44,829 34,854 56,203 Unvested shares at end of year 157,860 96,127 71,706 Unrecognized compensation expense at end of year $ 3,923 $ 2,215 $ 2,003 TSR Awards TSR shares granted during the year 69,814 64,910 47,848 TSR shares vested during the year 43,730 77,174 71,299 TSR shares earned based on market metrics 48,890 58,652 — Unvested TSR shares at end of year 130,567 107,854 122,133 Unrecognized compensation expense at end of year $ 3,533 $ 2,653 $ 2,296 CEPS Awards CEPS shares granted during the year 69,814 64,910 47,848 CEPS shares vested during the year 43,730 38,590 35,622 CEPS shares earned based on market metrics — 26,627 63,763 Unvested CEPS shares at end of year 130,567 107,854 83,464 Unrecognized compensation expense at end of year $ 2,471 $ 1,223 $ 1,090 Outstanding restricted, TSR and CEPS share awards include a dividend component that is paid in cash. A liability for the dividends payable related to these awards is accrued as dividends are announced throughout the life of the award. As of December 31, 2022 and 2021, the Company had recognized a liabi lity of $ 1.7 million and $ 1.5 million, respectively, related to the dividend equivalents payable on the outstanding and unvested share grants. Other Income - Net Other income - net consisted of the following items for the years ended December 31 (dollars in thousands): 2022 2021 2020 Interest income $ ( 1,957 ) $ ( 1,943 ) $ ( 1,952 ) Interest on regulatory deferrals ( 1,914 ) ( 1,206 ) ( 1,222 ) Equity-related AFUDC ( 6,704 ) ( 7,004 ) ( 6,970 ) Non-service portion of pension and other postretirement benefit ( 3,037 ) 1,386 6,433 Earnings on investments ( 48,492 ) ( 21,402 ) ( 905 ) Other income ( 613 ) ( 3,129 ) ( 201 ) Total $ ( 62,717 ) $ ( 33,298 ) $ ( 4,817 ) Earnings per Common Share Basic earnings per common share is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted earnings per common share is calculated by dividing net income by diluted weighted-average common shares outstanding during the period, including common stock equivalent shares outstanding using the treasury stock method, unless such shares are anti-dilutive. Common stock equivalent shares include shares issuable under contingent stock awards. See Note 21 for earnings per common share calculations. Cash and Cash Equivalents For the purposes of the Consolidated Statements of Cash Flows, the Company considers all temporary investments with a maturity of three months or less when purchased to be cash equivalents. Allowance for Doubtful Accounts The Company maintains an allowance for doubtful accounts to provide for estimated and potential losses on accounts receivable. The Company determines the allowance for utility and other customer accounts receivable based on historical write-offs as compared to accounts receivable and operating revenues. Additionally, the Company establishes specific allowances for certain individual accounts. The following table presents the activity in the allowance for doubtful accounts during the years ended December 31 (dollars in thousands): 2022 2021 2020 Allowance as of the beginning of the year $ 10,465 $ 11,387 $ 2,419 Additions expensed during the year (1) 149 9,279 11,280 Net deductions (2) ( 4,141 ) ( 10,201 ) ( 2,312 ) Allowance as of the end of the year $ 6,473 $ 10,465 $ 11,387 (1) Increases in 2021 and 2020 related to COVID-19 bad debt expense in excess of the amount recovered through rates. (2) Increase in 2021 relates to COVID forgiveness program. The Company also received support from various government agencies in 2022 in the amount of $ 6.1 million, which was applied to overdue customer accounts. Utility Plant in Service The cost of additions to utility plant in service, including an allowance for funds used during construction and replacements of units of property and improvements, is capitalized. The cost of depreciable units of property retired plus the cost of removal less salvage is charged to accumulated depreciation. Asset Retirement Obligations The Company records the fair value of a liability for an ARO in the period in which it is incurred. When the liability is initially recorded, the associated costs of the ARO are capitalized as part of the carrying amount of the related long-lived asset. The liability is accreted to its present value each period and the related capitalized costs are depreciated over the useful life of the related asset. In addition, if there are changes in the estimated timing or estimated costs of the AROs, adjustments are recorded during the period new information becomes available as an increase or decrease to the liability, with the offset recorded to the related long-lived asset. Upon retirement of the asset, the Company either settles the ARO for its recorded amount or recognizes a regulatory asset or liability for the difference, which will be surcharged/refunded to customers through the ratemaking process. The Company records regulatory assets and liabilities for the difference between asset retirement costs currently recovered in rates and AROs recorded since asset retirement costs are recovered through rates charged to customers (see Note 11 for further discussion of the Company's AROs). The Company recovers certain asset retirement costs through rates charged to customers as a portion of its depreciation expense for which the Company has not recorded asset retirement obligations. The Company has recorded the amount of estimated retirement costs collected from customers (that do not represent legal or contractual obligations) and included them as a non-current regulatory liability on the Consolidated Balance Sheets in the following amounts as of December 31 (dollars in thousands): 2022 2021 Regulatory liability for utility plant retirement costs $ 376,817 $ 350,190 Goodwill Goodwill arising from acquisitions represents the future economic benefit arising from other assets acquired in a business combination that are not individually identified and separately recognized. The Company evaluates goodwill for impairment using a fair value to carrying amount comparison (Step 1). The Company completed its annual evaluation of goodwill for potential impairment as of November 30, 2022 and determined that goodwill was not impaired at that time (carrying value was less than the determined fair value). There were no events or circumstances that changed between November 30, 2022 and December 31, 2022 that would more likely than not reduce the fair values of the reporting units below their carrying amounts. There were no changes in the carrying amount of goodwill during 2021 and 2022 and the balance was as follows (dollars in thousands): AEL&P Accumulated Impairment Losses Total Balance as of December 31, 2021 and 2022 $ 52,426 $ - $ 52,426 Derivative Assets and Liabilities Derivatives are recorded as either assets or liabilities on the Consolidated Balance Sheets measured at estimated fair value. The WUTC and the IPUC issued accounting orders authorizing Avista Corp. to offset energy commodity derivative assets or liabilities with a regulatory asset or liability. This accounting treatment is intended to defer the recognition of mark-to-market gains and losses on energy commodity transactions until the period of delivery. Realized benefits and costs result in adjustments to retail rates through PGAs, the ERM in Washington, the PCA mechanism in Idaho, and periodic general rates cases. The resulting regulatory assets associated with energy commodity derivative instruments have been concluded to be probable of recovery through future rates. Substantially all forward contracts to purchase or sell power and natural gas are recorded as derivative assets or liabilities at estimated fair value with an offsetting regulatory asset or liability. Contracts that are not considered derivatives are accounted for on the accrual basis until they are settled or realized unless there is a decline in the fair value of the contract that is determined to be other-than-temporary. For interest rate swap derivatives, Avista Corp. records all mark-to-market gains and losses in each accounting period as assets and liabilities, as well as offsetting regulatory assets and liabilities, such that there is no income statement impact. The interest rate swap derivatives are risk management tools similar to energy commodity derivatives. Upon settlement of interest rate swap derivatives, the regulatory asset or liability is amortized as a component of interest expense over the term of the associated debt. The Company records an offset of interest rate swap derivative assets and liabilities with regulatory assets and liabilities, based on the prior practice of the commissions to provide recovery through the ratemaking process. The Company has multiple master netting agreements with a variety of entities that allow for cross-commodity netting of derivative agreements with the same counterparty (i.e. power derivatives can be netted with natural gas derivatives). In addition, some master netting agreements allow for the netting of commodity derivatives and interest rate swap derivatives for the same counterparty. The Company does not have any agreements which allow for cross-affiliate netting among multiple affiliated legal entities. The Company nets all derivative instruments when allowed by the agreement for presentation in the Consolidated Balance Sheets. Fair Value Measurements Fair value represents the price that would be received when selling an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. Energy commodity derivative assets and liabilities, deferred compensation assets, some equity investments, as well as derivatives related to interest rate swap derivatives and foreign currency exchange derivatives, are reported at estimated fair value on the Consolidated Balance Sheets. See Note 18 for the Company’s fair value disclosures. Regulatory Deferred Charges and Credits The Company prepares its consolidated financial statements in accordance with regulatory accounting practices because: • rates for regulated services are established by or subject to approval by independent third-party regulators, • the regulated rates are designed to recover the cost of providing the regulated services, and • in view of demand for the regulated services and the level of competition, it is reasonable to assume that rates can be charged to and collected from customers at levels that will recover costs. Regulatory accounting practices require that certain costs and/or obligations (such as incurred power and natural gas costs not currently reflected in rates, but expected to be recovered or refunded in the future), are reflected as deferred charges or credits on the Consolidated Balance Sheets. These costs and/or obligations are not reflected in the Consolidated Statements of Income until the period during which matching revenues are recognized. The Company also has decoupling revenue deferrals. See Note 4 for discussion on decoupling revenue deferrals. If at some point in the future the Company determines that it no longer meets the criteria for continued application of regulatory accounting practices for all or a portion of its regulated operations, the Company could be: • required to write off its regulatory assets, and • precluded from the future deferral of costs or decoupled revenues not recovered through rates at the time such amounts are incurred, even if the Company expected to recover these amounts from customers in the future. See Note 23 for further details of regulatory assets and liabilities. Unamortized Debt Expense Unamortized debt expense includes debt issuance costs that are amortized over the life of the related debt. These costs are recorded as an offset to Long-Term Debt on the Consolidated Balance Sheets. Unamortized Debt Repurchase Costs Premiums paid or discounts received to repurchase debt are amortized over the remaining life of the original debt that was repurchased or, if new debt is issued in connection with the repurchase, these costs are amortized over the life of the new debt. These costs are recovered through retail rates as a component of interest expense. Appropriated Retained Earnings In accordance with the hydroelectric licensing requirements of section 10(d) of the Federal Power Act (FPA), the Company maintains an appropriated retained earnings account for any earnings in excess of the specified rate of return on the Company's investment in the licenses for its various hydroelectric projects. Per section 10(d) of the FPA, the Company must maintain these excess earnings in an appropriated retained earnings account until the termination of the licensing agreements or apply them to reduce the net investment in the licenses of the hydroelectric projects at the discretion of the FERC. The Company calculates the earnings in excess of the specified rate of return on an annual basis, usually during the second quarter. The appropriated retained earnings amounts included in retained earnings were as follows as of December 31 (dollars in thousands): 2022 2021 Appropriated retained earnings $ 57,231 $ 53,620 Contingencies The Company has unresolved regulatory, legal and tax issues which have inherently uncertain outcomes. The Company accrues a loss contingency if it is probable that a liability has been incurred and the amount of the loss or impairment can be reasonably estimated. The Company also discloses loss contingencies that do not meet these conditions for accrual, if there is a reasonable possibility that a material loss may be incurred. As of December 31, 2022, the Company has not recorded any significant amounts related to unresolved contingencies. See Note 22 for further discussion of the Company's commitments and contingencies.

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2022
Accounting Standards Update and Change in Accounting Principle [Abstract]
New Accounting Standards	NOTE 2. NEW ACCOUNTING STANDARDS ASU 2022-03 "Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions In June 2022, the FASB issued ASU 2022-03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions . The purpose of this guidance is to clarify that a contractual restriction on the ability to sell an equity security is not considered part of the unit of account of the equity security, and therefore should not be considered when measuring the equity security's fair value. Additionally, an entity cannot separately recognize and measure a contractual sale restriction. This guidance also adds specific disclosures related to equity securities that are subject to contractual sale restrictions, including (i) the fair value of equity securities subject to contractual sale restrictions reflected in the balance sheet and (ii) the nature and remaining duration of the restrictions, and (iii) the circumstances that could cause a lapse in the restrictions. The amendments are effective on January 1, 2024, with early adoption permitted. The amendments must be applied using a prospective approach with any adjustments from the adoption of the amendments recognized in earnings and disclosed upon adoption. The Company does not expect the impact of these amendments to be material.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	NOTE 3. BALANCE SHEET COMPONENTS Materials and Supplies, Fuel Stock and Stored Natural Gas Inventories of materials and supplies, fuel stock and stored natural gas are recorded at average cost for regulated operations and the lower of cost or market for non-regulated operations and consisted of the following as of December 31 (dollars in thousands): 2022 2021 Materials and supplies $ 75,766 $ 62,003 Stored natural gas 26,788 17,604 Fuel stock 5,120 5,126 Total $ 107,674 $ 84,733 Other Current Assets Other current assets consisted of the following as of December 31 (dollars in thousands): 2022 2021 Collateral posted for derivative instruments after netting with outstanding $ 66,142 $ 21,477 Prepayments 30,201 24,387 Income taxes receivable 30,740 29,615 Derivative assets net of collateral 18,198 1,442 Other 5,886 3,833 Total $ 151,167 $ 80,754 Other Property and Investments-Net and Other Non-Current Assets Other property and investments-net and other non-current assets consisted of the following as of December 31 (dollars in thousands): 2022 2021 Equity investments $ 147,809 $ 91,057 Operating lease ROU assets 68,238 70,133 Finance lease ROU assets 40,056 43,697 Non-utility property 25,401 20,033 Notes receivable 17,954 14,949 Long-term prepaid license fees 17,936 8,465 Pension assets 13,382 — Investment in affiliated trust 11,547 11,547 Deferred compensation assets 7,541 9,513 Other 15,221 11,149 Total $ 365,085 $ 280,543 Other Current Liabilities Other current liabilities consisted of the following as of December 31 (dollars in thousands): 2022 2021 Accrued taxes other than income taxes $ 38,568 $ 41,706 Employee paid time off accruals 29,279 27,741 Accrued interest 20,863 17,538 Pensions and other postretirement benefits 15,625 13,582 Derivative liabilities 26,910 28,801 Deferred wholesale revenue 8,481 884 Other 49,689 38,609 Total $ 189,415 $ 168,861 Other Non-Current Liabilities and Deferred Credits Other non-current liabilities and deferred credits consisted of the following as of December 31 (dollars in thousands): 2022 2021 Operating lease liabilities $ 64,284 $ 66,068 Finance lease liabilities 42,495 45,730 Deferred investment tax credits 28,784 29,313 Asset retirement obligations 15,783 17,142 Derivative liabilities 7,892 4,525 Other 16,617 15,347 Total $ 175,855 $ 178,125

Revenue

Revenue	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Revenue	NOTE 4. REVENUE ASC 606 defines the core principle of the revenue recognition model is that an entity should identify the various performance obligations in a contract, allocate the transaction price among the performance obligations and recognize revenue when (or as) the entity satisfies each performance obligation. Utility Revenues Revenue from Contracts with Customers General The majority of Avista Corp.’s revenue is from rate-regulated sales of electricity and natural gas to retail customers, which has two performance obligations, (1) having service available for a specified period (typically a month at a time) and (2) the delivery of energy to customers. The total energy price generally has a fixed component (basic charge) related to having service available and a usage-based component, related to the delivery and consumption of energy. The commodity is sold and/or delivered to and consumed by the customer simultaneously, and the provisions of the relevant utility commission authorization determine the charges the Company may bill the customer. Since all revenue recognition criteria are met upon the delivery of energy to customers, revenue is recognized immediately. In addition, the sale of electricity and natural gas is governed by the various state utility commissions, which set rates, charges, terms and conditions of service, and prices. Collectively, these rates, charges, terms and conditions are included in a “tariff,” which governs all aspects of the provision of regulated services. Tariffs are only permitted to be changed through a rate-setting process involving an independent, third-party regulator empowered by statute to establish rates that bind customers. Thus, all regulated sales by the Company are conducted subject to the regulator-approved tariff. Tariff sales involve the current provision of commodity service (electricity and/or natural gas) to customers for a price that generally has a basic charge and a usage-based component. Tariff rates also include certain pass-through costs to customers such as natural gas costs, retail revenue credits and other miscellaneous regulatory items that do not impact net income, but can cause total revenue to fluctuate significantly up or down compared to previous periods. The commodity is sold and/or delivered to and consumed by the customer simultaneously, and the provisions of the relevant tariff determine the charges the Company may bill the customer, payment due date, and other pertinent rights and obligations of both parties. Generally, tariff sales do not involve a written contract. Since all revenue recognition criteria are met upon the delivery of energy to customers, revenue is recognized immediately at that time. Revenues from contracts with customers are presented in the Consolidated Statements of Income in the line item “Utility revenues, exclusive of alternative revenue programs.” Unbilled Revenue from Contracts with Customers The determination of the volume of energy sales to individual customers is based on the reading of their meters, which occurs on a systematic basis throughout the month (once per month for each individual customer). At the end of each calendar month, the amount of energy delivered to customers since the date of the last meter reading is estimated and the corresponding unbilled revenue is estimated and recorded. The Company's estimate of unbilled revenue is based on: • the number of customers, • tariff rates, • meter reading dates, • actual native load for electricity, • actual throughput for natural gas, and • electric line losses and natural gas system losses. Any difference between actual and estimated revenue is automatically corrected in the following month when the meter reading and customer billing occurs. Accounts receivable includes unbilled energy revenues of the following amounts as of December 31 (dollars in thousands): 2022 2021 Unbilled accounts receivable $ 81,691 $ 74,479 Non-Derivative Wholesale Contracts The Company has certain wholesale contracts which are not accounted for as derivatives and, accordingly, are within the scope of ASC 606 and considered revenue from contracts with customers. Revenue is recognized as energy is delivered to the customer or the service is available for specified period of time, consistent with the discussion of rate regulated sales above. Alternative Revenue Programs (Decoupling) ASC 606 retained existing GAAP associated with alternative revenue programs, which specified that alternative revenue programs are contracts between an entity and a regulator of utilities, not a contract between an entity and a customer. GAAP requires that an entity present revenue arising from alternative revenue programs separately from revenues arising from contracts with customers on the Consolidated Statements of Income. The Company's decoupling mechanisms (also known as a FCA in Idaho) qualify as alternative revenue programs. Decoupling revenue deferrals are recognized in the Consolidated Statements of Income during the period they occur (i.e. during the period of revenue shortfall or excess due to fluctuations in customer usage), subject to certain limitations, and a regulatory asset or liability is established which will be surcharged or rebated to customers in future periods. GAAP requires that for any alternative revenue program, like decoupling, the revenue must be expected to be collected from customers within 24 months of the deferral to qualify for recognition in the Consolidated Statements of Income. Any amounts included in the Company's decoupling program that are not expected to be collected from customers within 24 months are not recorded in the financial statements until the period in which revenue recognition criteria are met. The amounts expected to be collected from customers within 24 months represents an estimate which must be made by the Company on an ongoing basis due to it being based on the volumes of electric and natural gas sold to customers on a go-forward basis. The Company records alternative program revenues under the gross method, which is to amortize the decoupling regulatory asset/liability to the alternative revenue program line item on the Consolidated Statements of Income as it is collected from or refunded to customers. The cash passing between the Company and the customers is presented in revenue from contracts with customers since it is a portion of the overall tariff paid by customers. This method results in a gross-up to both revenue from contracts with customers and revenue from alternative revenue programs, but has a net zero impact on total revenue. Depending on whether the previous deferral balance being amortized was a regulatory asset or regulatory liability, and depending on the size and direction of the current year deferral of surcharges and/or rebates to customers, it could result in negative alternative revenue program revenue during the year. Derivative Revenue Most wholesale electric and natural gas transactions (including both physical and financial transactions), and the sale of fuel are considered derivatives, which are specifically scoped out of ASC 606. As such, these revenues are disclosed separately from revenue from contracts with customers. Revenue is recognized for these items upon the settlement/expiration of the derivative contract. Derivative revenue includes those transactions that are entered into and settled within the same month. Other Utility Revenue Other utility revenue includes rent, sales of materials, late fees and other charges that do not represent contracts with customers. This revenue is scoped out of ASC 606, as this revenue does not represent items where a customer is a party that has contracted with the Company to obtain goods or services that are an output of the Company’s ordinary activities in exchange for consideration. As such, these revenues are presented separately from revenue from contracts with customers. Other Considerations for Utility Revenues Gross Versus Net Presentation Revenues and resource costs from Avista Utilities’ settled energy contracts that are “booked out” (not physically delivered) are reported on a net basis as part of derivative revenues. Utility-related taxes collected from customers (primarily state excise taxes and city utility taxes) are taxes imposed on Avista Utilities as opposed to being imposed on customers; therefore, Avista Utilities is the taxpayer and records these transactions on a gross basis in revenue from contracts with customers and operating expense (taxes other than income taxes). The utility-related taxes collected from customers at AEL&P are imposed on the customers rather than AEL&P; therefore, the customers are the taxpayers and AEL&P is acting as their agent. As such, these transactions at AEL&P are presented on a net basis within revenue from contracts with customers. Utility-related taxes that were included in revenue from contracts with customers were as follows for the years ended December 31 (dollars in thousands): 2022 2021 2020 Utility-related taxes $ 69,931 $ 62,736 $ 59,319 Significant Judgments and Unsatisfied Performance Obligations The only significant judgments involving revenue recognition are estimates surrounding unbilled revenue and receivables from contracts with customers and estimates surrounding the amount of decoupling revenues that will be collected from customers within 24 months (discussed above). The Company has certain capacity arrangements, where the Company has a contractual obligation to provide either electric or natural gas capacity to its customers for a fixed fee. Most of these arrangements are paid for in arrears by the customers and do not result in deferred revenue and only result in receivables from the customers. The Company does have one capacity agreement where the customer makes payments throughout the year. As of December 31, 2022, the Company estimates it had unsatisfied capacity performance obligations of $ 11.7 million, which will be recognized as revenue in future periods as the capacity is provided to the customers. These performance obligations are not reflected in the financial statements, as the Company has not received payment for these services. Disaggregation of Total Operating Revenue The following table disaggregates total operating revenue by segment and source for the years ended December 31 (dollars in thousands): 2022 2021 2020 Avista Utilities Revenue from contracts with customers $ 1,400,027 $ 1,233,904 $ 1,157,746 Derivative revenues 286,309 152,590 110,313 Alternative revenue programs ( 33,357 ) ( 6,635 ) ( 3,814 ) Deferrals and amortizations for rate refunds to customers 207 2,984 5,335 Other utility revenues 10,629 10,156 7,888 Total Avista Utilities 1,663,815 1,392,999 1,277,468 AEL&P Revenue from contracts with customers 45,703 45,051 42,624 Deferrals and amortizations for rate refunds to customers ( 614 ) ( 190 ) ( 190 ) Other utility revenues 615 505 375 Total AEL&P 45,704 45,366 42,809 Other Revenue from contracts with customers — 2 564 Other revenues 688 569 1,050 Total Other 688 571 1,614 Total operating revenues $ 1,710,207 $ 1,438,936 $ 1,321,891 Utility Revenue from Contracts with Customers by Type and Service The following table disaggregates revenue from contracts with customers associated with the Company's electric operations for the years ended December 31 (dollars in thousands): 2022 2021 2020 Avista Utilities AEL&P Total Utility Avista Utilities AEL&P Total Utility Avista Utilities AEL&P Total Utility ELECTRIC OPERATIONS Revenue from Residential $ 414,823 $ 19,667 $ 434,490 $ 394,717 $ 18,940 $ 413,657 $ 377,785 $ 18,618 $ 396,403 Commercial and 338,656 25,782 364,438 326,173 25,861 352,034 303,972 23,754 327,726 Industrial 107,740 — 107,740 106,756 — 106,756 103,103 — 103,103 Public street and 7,483 254 7,737 7,472 250 7,722 7,303 252 7,555 Total retail 868,702 45,703 914,405 835,118 45,051 880,169 792,163 42,624 834,787 Transmission 32,307 — 32,307 21,005 — 21,005 18,236 — 18,236 Other revenue from 49,920 — 49,920 33,870 — 33,870 19,252 — 19,252 Total revenue $ 950,929 $ 45,703 $ 996,632 $ 889,993 $ 45,051 $ 935,044 $ 829,651 $ 42,624 $ 872,275 The following table disaggregates revenue from contracts with customers associated with the Company's natural gas operations for the years ended December 31 (dollars in thousands): 2022 2021 2020 Avista Utilities Avista Utilities Avista Utilities NATURAL GAS OPERATIONS Revenue from contracts with customers Residential $ 284,452 $ 221,405 $ 213,612 Commercial 139,923 100,819 94,937 Industrial and interruptible 10,471 7,796 7,128 Total retail revenue 434,846 330,020 315,677 Transportation 8,627 8,547 7,917 Other revenue from contracts with customers 5,625 5,344 4,501 Total revenue from contracts with customers $ 449,098 $ 343,911 $ 328,095

Leases

Leases	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Leases	NOTE 5. LEASES ASC 842 outlines a model for lease accounting. The core principle of the model is that an entity should recognize the ROU assets and liabilities from leases on the balance sheet and depreciate or amortize the asset and liability over the term of the lease, as well as provide disclosure to enable users of the consolidated financial statements to assess the amount, timing, and uncertainty of cash flows from leases. Significant Judgments and Assumptions The Company determines if an arrangement is a lease, as well as its classification, at its inception. ROU assets represent the Company's right to use an underlying asset for the lease term, and lease liabilities represent the Company's obligation to make lease payments. Operating and finance lease ROU assets and lease liabilities are recognized at the commencement date of the agreement based on the present value of lease payments over the lease term. As most of the Company's leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date to determine the present value of lease payments. The implicit rate is used when it is readily determinable. The operating and finance lease ROU assets also include any lease payments made and exclude lease incentives, if any, that accrue to the benefit of the lessee. Lease terms may include options to extend or terminate the lease when it is reasonably certain the Company will exercise that option. Lease expense is recognized on a straight-line basis over the lease term. The difference between lease expense and cash paid for leased assets is recognized as a regulatory asset or regulatory liability. Description of Leases Operating Leases The Company's most significant operating lease is with the State of Montana associated with submerged land around the Company's hydroelectric facilities in the Clark Fork River basin, which expires in 2046 . The terms of this lease are subject to adjustment - depending on the outcome of ongoing litigation between the State of Montana and NorthWestern. In addition, the State of Montana and Avista Corp. are engaged in litigation regarding lease terms, including how much money, if any, the State of Montana should return to Avista Corp. Amounts recorded for this lease are uncertain and amounts may change in the future depending on the outcome of the ongoing litigation. Any reduction in future lease payments or the return of previously paid amounts to Avista Corp. will be included in the future ratemaking process. In addition to the lease with the State of Montana, the Company also has other operating leases for land associated with its utility operations, as well as communication sites which support network and radio communications within its service territory. The Company's leases have remaining terms of 1 to 71 years . Most of the Company's leases include options to extend the lease term for periods of 5 to 50 years . Options are exercised at the Company's discretion. Certain of the Company's lease agreements include rental payments which are periodically adjusted over the term of the agreement based on the consumer price index. The Company's lease agreements do not include any material residual value guarantees or material restrictive covenants. Avista Corp. does not record leases with a term of 12 months or less in the Consolidated Balance Sheets. Total short-term lease costs for the year ended December 31, 2022 are immaterial. Finance Lease AEL&P has a PPA which is a finance lease for accounting purposes related to the Snettisham hydroelectric project, which expires in 2034 . For ratemaking purposes, this lease is an operating lease with a constant level of annual rental expense (straight line rent expense). Because of this regulatory treatment, any difference between the operating lease expense for ratemaking purposes and the expenses recognized under GAAP (interest expense and amortization of the finance lease ROU asset) is recorded as a regulatory asset and amortized during the later years of the lease when the finance lease expense is less than the operating lease expense included in base rates. The amortization of the ROU asset is included in depreciation and amortization and the interest associated with the lease liability is included in interest expense on the Consolidated Statements of Income. The components of lease expense were as follows for the year ended December 31 (dollars in thousands): 2022 2021 Operating lease cost: Fixed lease cost (Other operating expenses) $ 4,986 $ 4,970 Variable lease cost (Other operating expenses) 1,567 1,180 Total operating lease cost $ 6,553 $ 6,150 Finance lease cost: Amortization of ROU asset (Depreciation and amortization) $ 3,641 $ 3,641 Interest on lease liabilities (Interest expense) 2,375 2,522 Total finance lease cost $ 6,016 $ 6,163 Supplemental cash flow information related to leases was as follows for the year ended December 31 (dollars in thousands): 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash outflows: Operating lease payments $ 4,828 $ 4,805 Interest on finance lease 2,375 2,522 Total operating cash outflows $ 7,203 $ 7,327 Finance cash outflows: Principal payments on finance lease $ 3,085 $ 2,935 Supplemental balance sheet information related to leases was as follows for December 31 (dollars in thousands): December 31, December 31, 2022 2021 Operating Leases Operating lease ROU assets (Other property and investments-net $ 68,238 $ 70,133 Other current liabilities $ 4,349 $ 4,301 Other non-current liabilities and deferred credits 64,284 66,068 Total operating lease liabilities $ 68,633 $ 70,369 Finance Leases Finance lease ROU assets (Other property and investments-net $ 40,056 $ 43,697 Other current liabilities $ 3,235 $ 3,085 Other non-current liabilities and deferred credits 42,495 45,730 Total finance lease liabilities $ 45,730 $ 48,815 Weighted Average Remaining Lease Term Operating leases 23.28 years 24.22 years Finance leases 5.42 years 6.32 years Weighted Average Discount Rate Operating leases 4.28 % 4.28 % Finance leases 4.07 % 4.35 % Maturities of lease liabilities (including principal and interest) were as follows as of December 31, 2022 (dollars in thousands): Operating Leases Finance Leases 2023 $ 4,850 $ 5,456 2024 4,877 5,459 2025 4,884 5,454 2026 4,869 5,456 2027 4,880 5,458 Thereafter 86,991 32,748 Total lease payments $ 111,351 $ 60,031 Less: imputed interest ( 42,718 ) ( 14,301 ) Total $ 68,633 $ 45,730 Maturities of lease liabilities (including principal and interest) were as follows as of December 31, 2021 (dollars in thousands): Operating Leases Finance Leases 2022 $ 4,820 $ 5,460 2023 4,849 5,456 2024 4,875 5,459 2025 4,882 5,454 2026 4,867 5,456 Thereafter 91,845 38,204 Total lease payments $ 116,138 $ 65,489 Less: imputed interest ( 45,769 ) ( 16,674 ) Total $ 70,369 $ 48,815

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	NOTE 6. VARIABLE INTEREST ENTITIES Lancaster Power Purchase Agreement The Company has a PPA for the purchase of all the output of the Lancaster Plant, a 270 MW natural gas-fired combined cycle combustion turbine plant located in Kootenai County, Idaho, owned by an unrelated third-party (Rathdrum Power LLC(Rathdrum)), through 2026. Avista Corp. has a variable interest in Rathdrum through the PPA. Accordingly, Avista Corp. made an evaluation of which interest holders have the power to direct the activities that most significantly impact the economic performance of Rathdrum and which interest holders have the obligation to absorb losses or receive benefits that could be significant to Rathdrum. Avista Corp. pays a fixed capacity and operations and maintenance payment and certain monthly variable costs under the PPA. Under the terms of the PPA, Avista Corp. makes the dispatch decisions, provides all natural gas fuel and receives all of the electric energy output from the plant. However, Rathdrum as the owner of the plant controls the daily operation of the plant and makes operating and maintenance decisions, both during the term of the PPA and after its expiration in 2026. Also, Rathdrum controls the rights and obligations with respect to the plant after the PPA expiration and Avista Corp. will not have further obligations with respect to the plant. It is estimated that the plant will have 15 to 25 years of useful life after that time. Rathdrum bears the maintenance risk of the plant and will receive the residual value of the plant. Avista Corp. has no debt or equity investments in the Lancaster Plant and does not provide financial support through liquidity arrangements or other commitments (other than the PPA). Based on its analysis, Avista Corp. does not consider itself to be the primary beneficiary of Rathdrum or the plant. Accordingly, neither the Lancaster Plant nor Rathdrum is included in Avista Corp.’s consolidated financial statements. The Company has a future contractual obligatio n of $ 117.4 million under the PPA (representing the fixed capacity and operations and maintenance payments through 2026) and believes this would be its maximum exposure to loss. The Company believes that such costs will be recovered through retail rates. Limited Partnerships and Similar Entities Under GAAP, a limited partnership or similar legal entity that is the functional equivalent of a limited partnership is considered a VIE regardless of whether it otherwise qualifies as a voting interest entity unless a simple majority or lower threshold of the “unrelated” limited partners (i.e., parties other than the general partner, entities under common control with the general partner, and other parties acting on behalf of the general partner) have substantive kick-out rights (including liquidation rights) or participating rights. The Company has investments in limited partnerships (or the functional equivalent) where Avista Corp. is a limited partner investor in an investment fund where the general partner makes all of the investment and operating decisions with regards to the partnership and fund. To remove the general partner from any of the funds, approval from greater than a simple majority of the limited partners is required. As such, the limited partners do not have substantive kick-out rights and these investments are considered VIEs. Consolidation of these VIEs by Avista Corp. is not required because the Company does not have majority ownership in any of the funds, it does not have the power to direct any activities of the funds, and it does not have the power to appoint executive leadership, including the board of directors. Avista Corp. participates in profits and losses of the investment funds based on its ownership percentage and its losses are capped at its total initial investment in the funds. Equity investments in VIEs are accounted for under the equity method (see Note 7). As of December 31, 2022 , Avista Corp. has invested $ 63.4 million in these investment funds, with an additional commitment of $ 25.6 million remaining to be invested. The Company is not allowed to withdraw any capital contributions from any investment fund until after that fund expiration date and all liabilities of that fund are settled . The expiration dates range from 2025 to 2036 , with some investments having no termination date (as they are perpetual). As of December 31, 2022 , the Company has a total carrying amount of $ 79.8 million in these VIEs, including $ 70.2 million of equity investments and $ 9.6 million of notes receivable.

Equity Investments

Equity Investments	12 Months Ended
	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Equity Investments	NOTE 7. EQUITY INVESTMENTS The Company has equity investment holdings that are accounted for under the equity method, at fair value, or using the fair value measurement alternative provided for in ASC 321, adjusting cost for impairment and observable price changes. The following table summarizes Avista Corp.’s equity investments, which are included in “Other property and investments- net and other non-current assets” on the Consolidated Balance Sheets as of December 31 (dollars in thousands): 2022 2021 Equity method investments $ 70,196 $ 66,896 Investments without readily determinable fair value Non-recurring fair value 23,329 24,161 Recurring fair value 54,284 — Total $ 147,809 $ 91,057 Equity Method Investments The Company has investments in limited partnerships (or the functional equivalent) where Avista Corp. is a limited partner investor in an investment fund. Holdings in these investment funds are accounted for under the equity method. Underlying investments held by the funds are recorded at fair value by the fund, and Avista Corp. recognizes its share of the fund's profits and losses based on its ownership percentage. The Company also has ownership in joint ventures with underlying holdings in real estate, which are also accounted for under the equity method. The Company's earnings and losses related to equity method investments are included in “Other income- net” on the Consolidated Statements of Net Income. Investments Without Readily Determinable Fair Value The Company has investments that do not qualify for equity method treatment, and for which fair value is not readily determinable. The Company has elected the measurement alternative for a majority of these investments, adjusting the recorded value on a non-recurring basis as a result of observable transactions involving the underlying asset. The observable transaction indicates an updated fair value, and the Company adjusts carrying value to fair value at this point in time. The fair value of these assets is determined using the market approach, and these assets are considered level 2 on the fair value hierarchy (see Note 18 for a description of the fair value hierarchy). The Company has elected to record two investments at fair value on a recurring basis. These equity investments are considered level 3 on the fair value hierarchy. See further discussion of level 3 equity investments, including valuation methods and significant inputs, as included in Note 18. Realized and unrealized gains or losses in equity investments are included in net income. The following table summarizes net unrealized gains related to investments without readily determinable fair value held as of the end of the respective period for the years ended December 31 (dollars in thousands): 2022 2021 2020 Investments recorded at non-recurring fair value $ 12,285 $ 8,761 $ 925 Investments recorded at recurring fair value 33,382 — — Total $ 45,667 $ 8,761 $ 925 Net unrealized gains recorded related to investments recorded at non-recurring fair value result from identified observable transactions. On a cumulative basis, the Company has recognized a net g ain of $ 14.8 million f or fair value adjustments to investments recorded at non-recurring fair value held at December 31, 2022.

Derivatives and Risk Management

Derivatives and Risk Management	12 Months Ended
	Dec. 31, 2022
Derivative Instruments and Hedges, Assets [Abstract]
Derivatives and Risk Management	NOTE 8. DERIVATIVES AND RISK MANAGEMENT Energy Commodity Derivatives Avista Corp. is exposed to market risks relating to changes in electricity and natural gas commodity prices and certain other fuel prices. Market risk is, in general, the risk of fluctuation in the market price of the commodity being traded and is influenced primarily by supply and demand. Market risk includes the fluctuation in the market price of associated derivative commodity instruments. Avista Corp. utilizes derivative instruments, such as forwards, futures, swap derivatives and options in order to manage the various risks relating to these commodity price exposures. Avista Corp. has an energy resources risk policy and control procedures to manage these risks. As part of Avista Corp.'s resource procurement and management operations in the electric business, the Company engages in an ongoing process of resource optimization, which involves the economic selection from available energy resources to serve Avista Corp.'s load obligations and the use of these resources to capture available economic value through wholesale market transactions. These include sales and purchases of electric capacity and energy, fuel for electric generation, and derivative contracts related to capacity, energy and fuel. Such transactions are part of the process of matching resources with load obligations and hedging a portion of the related financial risks. These transactions range from terms of intra-hour up to multiple years. As part of its resource procurement and management of its natural gas business, Avista Corp. makes continuing projections of its natural gas loads and assesses available natural gas resources including natural gas storage availability. Natural gas resource planning typically includes peak requirements, low and average monthly requirements and delivery constraints from natural gas supply locations to Avista Corp.'s distribution system. However, daily variations in natural gas demand can be significantly different than monthly demand projections. On the basis of these projections, Avista Corp. plans and executes a series of transactions to hedge a portion of its projected natural gas requirements through forward market transactions and derivative instruments. These transactions may extend as much as three natural gas operating years (November through October) into the future. Avista Corp. also leaves a significant portion of its natural gas supply requirements unhedged for purchase in short-term and spot markets. Avista Corp. plans for sufficient natural gas delivery capacity to serve its retail customers for a theoretical peak day event. Avista Corp. generally has more pipeline and storage capacity than what is needed during periods other than a peak day. Avista Corp. optimizes its natural gas resources by using market opportunities to generate economic value that mitigates the fixed costs. Avista Corp. also optimizes its natural gas storage capacity by purchasing and storing natural gas when prices are traditionally lower, typically in the summer, and withdrawing during higher priced months, typically during the winter. However, if market conditions and prices indicate that Avista Corp. should buy or sell natural gas at other times during the year, Avista Corp. engages in optimization transactions to capture value in the marketplace. Natural gas optimization activities include, but are not limited to, wholesale market sales of surplus natural gas supplies, purchases and sales of natural gas to optimize use of pipeline and storage capacity, and participation in the transportation capacity release market. The following table presents the underlying energy commodity derivative volumes as of December 31, 2022 that are expected to be delivered in each respective year (in thousands of MWhs and mmBTUs): Purchases Sales Electric Derivatives Gas Derivatives Electric Derivatives Gas Derivatives Year Physical (1) Financial (1) Physical (1) Financial (1) Physical (1) Financial (1) Physical (1) Financial (1) 2023 5 — 19,140 79,253 136 1,011 4,145 29,473 2024 — — 533 30,658 — — 1,370 9,668 2025 — — 450 4,895 — — 1,115 1,125 As of December 31, 2022 , there are no expected deliveries of energy commodity derivatives afte r 2 0 25. The following table presents the underlying energy commodity derivative volumes as of December 31, 2021 that were expected to be delivered in each respective year (in thousands of MWhs and mmBTUs): Purchases Sales Electric Derivatives Gas Derivatives Electric Derivatives Gas Derivatives Year Physical (1) Financial (1) Physical (1) Financial (1) Physical (1) Financial (1) Physical (1) Financial (1) 2022 129 — 7,114 61,405 234 452 3,933 31,485 2023 — — 378 23,218 — — 1,360 9,323 2024 — — 228 3,413 — — 1,370 228 2025 — — — — — — 1,115 — As of December 31, 2021 , there were no expected deliveries of energy commodity derivatives after 2 0 25. (1) Physical transactions represent commodity transactions in which Avista Corp. will take or make delivery of either electricity or natural gas; financial transactions represent derivative instruments with delivery of cash in the amount of the benefit or cost but with no physical delivery of the commodity, such as futures, swap derivatives, options, or forward contracts. The electric and natural gas derivative contracts above will be included in either power supply costs or natural gas supply costs during the period they are scheduled to be delivered and will be included in the various deferral and recovery mechanisms (ERM, PCA, and PGAs), or in the general rate case process, and are expected to be collected through retail rates from customers. Foreign Currency Exchange Derivatives A significant portion of Avista Corp.'s natural gas supply (including fuel for power generation) is obtained from Canadian sources. Most of those transactions are executed in U.S. dollars, which avoids foreign currency risk. A portion of Avista Corp.’s short-term natural gas transactions and long-term Canadian transportation contracts are committed based on Canadian currency prices. The short term natural gas transactions are settled within 60 days with U.S. dollars. Avista Corp. hedges a portion of the foreign currency risk by purchasing Canadian currency exchange derivatives when such commodity transactions are initiated. The foreign currency exchange derivatives and the unhedged foreign currency risk have not had a material effect on Avista Corp.’s financial condition, results of operations or cash flows and these differences in cost related to currency fluctuations are included with natural gas supply costs for ratemaking. The following table summarizes the foreign currency exchange derivatives that Avista Corp. has outstanding as of December 31 (dollars in thousands): 2022 2021 Number of contracts 19 25 Notional amount (in United States dollars) $ 8,563 $ 8,571 Notional amount (in Canadian dollars) 11,659 10,957 Interest Rate Swap Derivatives Avista Corp. is affected by fluctuating interest rates related to a portion of its existing debt, and future borrowing requirements. Avista Corp. hedges a portion of its interest rate risk with financial derivative instruments, which may include interest rate swap derivatives and U.S. Treasury lock agreements. These interest rate swap derivatives and U.S Treasury lock agreements are considered economic hedges against fluctuations in future cash flows associated with anticipated debt issuances. The following table summarizes the unsettled interest rate swap derivatives that Avista Corp. has outstanding as of the balance sheet date indicated below (dollars in thousands): Balance Sheet Date Number of Contracts Notional Amount Mandatory Cash December 31, 2022 4 $ 40,000 2023 1 10,000 2024 December 31, 2021 13 $ 140,000 2022 2 20,000 2023 1 10,000 2024 See Note 16 for discussion of the bond purchase agreement and the related settlement of interest rate swaps in connection with the pricing of the bonds in March 2022. The fair value of outstanding interest rate swap derivatives can vary significantly from period to period depending on the total notional amount of swap derivatives outstanding and fluctuations in market interest rates compared to the interest rates fixed by the swaps. Avista Corp. is required to make cash payments to settle the interest rate swap derivatives when the fixed rates are higher than prevailing market rates at the date of settlement. Conversely, Avista Corp. receives cash to settle its interest rate swap derivatives when prevailing market rates at the time of settlement exceed the fixed swap rates. Summary of Outstanding Derivative Instruments The amounts recorded on the Consolidated Balance Sheets as of December 31, 2022 and December 31, 2021 reflect the offsetting of derivative assets and liabilities where a legal right of offset exists. The following table presents the fair values and locations of derivative instruments recorded on the Consolidated Balance Sheets as of December 31, 2022 (dollars in thousands): Fair Value Derivative and Balance Sheet Location Gross Gross Collateral Net Asset Foreign currency exchange derivatives Other current assets $ 43 $ — $ — $ 43 Other current liabilities — ( 3 ) — ( 3 ) Interest rate swap derivatives Other current assets 8,536 — — 8,536 Other property and investments-net and other non-current assets 2,648 — — 2,648 Other current liabilities — ( 52 ) — ( 52 ) Energy commodity derivatives Other current assets 32,257 ( 22,638 ) — 9,619 Other property and investments-net and other 312 ( 16 ) — 296 Other current liabilities 107,902 ( 229,607 ) 94,850 ( 26,855 ) Other non-current liabilities and deferred credits 6,049 ( 24,530 ) 10,589 ( 7,892 ) Total derivative instruments recorded on the $ 157,704 $ ( 276,846 ) $ 105,439 $ ( 13,703 ) The following table presents the fair values and locations of derivative instruments recorded on the Consolidated Balance Sheets as of December 31, 2021 (dollars in thousands): Fair Value Derivative and Balance Sheet Location Gross Gross Collateral Net Asset Foreign currency exchange derivatives Other current liabilities $ — $ ( 19 ) $ — $ ( 19 ) Interest rate swap derivatives Other property and investments-net and other non-current assets 1,149 — — 1,149 Other current liabilities 1,170 ( 25,196 ) — ( 24,026 ) Other non-current liabilities and deferred credits — ( 78 ) — ( 78 ) Energy commodity derivatives Other current assets 1,506 ( 107 ) — 1,399 Other property and investments-net and other 6,844 ( 5,335 ) — 1,509 Other current liabilities 25,771 ( 39,616 ) 9,089 ( 4,756 ) Other non-current liabilities and deferred credits 141 ( 4,589 ) — ( 4,448 ) Total derivative instruments recorded on the $ 36,581 $ ( 74,940 ) $ 9,089 $ ( 29,270 ) Exposure to Demands for Collateral Avista Corp.'s derivative contracts often require collateral (in the form of cash or letters of credit) or other credit enhancements, or reductions or terminations of a portion of the contract through cash settlement. In the event of a downgrade in Avista Corp.'s credit ratings or changes in market prices, additional collateral may be required. In periods of price volatility, the level of exposure can change significantly. As a result, sudden and significant demands may be made against Avista Corp.'s credit facilities and cash. Avista Corp. actively monitors the exposure to possible collateral calls and takes steps to mitigate capital requirements. The following table presents Avista Corp.'s collateral outstanding related to its derivative instruments as of December 31 (dollars in thousands): 2022 2021 Energy commodity derivatives Cash collateral posted $ 171,581 $ 30,567 Letters of credit outstanding 49,425 34,000 Balance sheet offsetting (cash collateral against net derivative positions) 105,439 9,089 There were no letters of credit outstanding related to interest rate swap derivatives as of December 31, 2022 and December 31, 2021. Certain of Avista Corp.’s derivative instruments contain provisions that require Avista Corp. to maintain an “investment grade” credit rating from the major credit rating agencies. If Avista Corp.’s credit ratings were to fall below “investment grade,” it would be in violation of these provisions, and the counterparties to the derivative instruments could request immediate payment or demand immediate and ongoing collateralization on derivative instruments in net liability positions. The following table presents the aggregate fair value of all derivative instruments with credit-risk-related contingent features that are in a liability position and the amount of additional collateral Avista Corp. could be required to post as of December 31 (dollars in thousands): 2022 2021 Interest rate swap derivatives Liabilities with credit-risk-related contingent features $ 52 $ 25,274 Additional collateral to post 52 25,274

Jointly Owned Electric Faciliti

Jointly Owned Electric Facilities	12 Months Ended
	Dec. 31, 2022
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Jointly Owned Electric Facilities	NOTE 9. JOINTLY OWNED ELECTRIC FACILITIES The Company has a 15 percent ownership interest in Units 3 and 4 of the Colstrip generating station, a coal-fired plant located in southeastern Montana, and provides financing for its ownership interest in the project. Pursuant to the ownership and operating agreements among the co-owners, the Company’s share of related fuel costs as well as operating expenses for plant in service are included in the corresponding accounts in the Consolidated Statements of Income. The Company’s share of utility plant in service for Colstrip and accumulated depreciation (inclusive of the ARO assets and accumulated amortization) were as follows as of December 31 (dollars in thousands): 2022 2021 Utility plant in service $ 390,852 $ 395,028 Accumulated depreciation ( 315,223 ) ( 302,220 ) See Note 11 for further discussion of AROs. While the obligations and liabilities with respect to Colstrip are to be shared among the co-owners on a pro-rata basis, many of the environmental liabilities are joint and several under the law, so that if any co-owner failed to pay its share of such liability, the other co-owners (or any one of them) could be required to pay the defaulting co-owner‘s share (or the entire liability). In January 2023, the Company entered into an agreement with NorthWestern to transfer its ownership in Colstrip Units 3 and 4. The Company will retain responsibility for remediation obligations in existence at the time the transaction closes. See further discussion of the transaction within Note 22 .

Property, Plant And Equipment

Property, Plant And Equipment	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	NOTE 10. PROPERTY, PLANT AND EQUIPMENT Net Utility Property Net utility property consisted of the following as of December 31 (dollars in thousands): 2022 2021 Utility plant in service $ 7,561,688 $ 7,166,580 Construction work in progress 164,147 205,405 Total 7,725,835 7,371,985 Less: Accumulated depreciation and amortization 2,281,126 2,146,470 Total net utility property $ 5,444,709 $ 5,225,515 Gross Property, Plant and Equipment The gross balances of the major classifications of property, plant and equipment are detailed in the following table as of December 31 (dollars in thousands): 2022 2021 Avista Utilities: Electric production $ 1,593,795 $ 1,494,371 Electric transmission 994,709 945,624 Electric distribution 2,236,376 2,093,937 Electric construction work-in-progress (CWIP) and other 376,981 424,733 Electric total 5,201,861 4,958,665 Natural gas underground storage 58,072 55,684 Natural gas distribution 1,452,637 1,356,477 Natural gas CWIP and other 88,264 87,852 Natural gas total 1,598,973 1,500,013 Common plant (including CWIP) 744,173 740,339 Total Avista Utilities 7,545,007 7,199,017 AEL&P: Electric production 106,390 106,094 Electric transmission 22,856 22,691 Electric distribution 29,269 27,138 Electric CWIP and other 12,295 7,319 Electric total 170,810 163,242 Common plant 10,018 9,726 Total AEL&P 180,828 172,968 Total gross utility property 7,725,835 7,371,985 Other (1) 16,631 17,818 Total $ 7,742,466 $ 7,389,803 (1) Included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets. Accumulated depreciation was $ 2.4 million as of December 31, 2022 and $ 2.3 million as of December 31, 2021 for the other businesses.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2022
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	NOTE 11. ASSET RETI REMENT OBLIGATIONS The Company has recorded liabilities for future AROs to: • restore coal ash containment ponds and coal holding areas at Colstrip, • cap a landfill at the Kettle Falls Plant, and • remove plant and restore the land at the Coyote Springs 2 site at the termination of the land lease. Due to an inability to estimate a range of settlement dates, the Company cannot estimate a liability for the: • removal and disposal of certain transmission and distribution assets, and • abandonment and decommissioning of certain hydroelectric generation and natural gas storage facilities. In 2015, the EPA issued a final rule regarding CCRs. Colstrip produces this byproduct. The CCR rule has been the subject of ongoing litigation. In August 2018, the D.C. Circuit struck down provisions of the rule. The rule includes technical requirements for CCR landfills and surface impoundments. The Colstrip owners developed a multi-year compliance plan to address the CCR requirements and existing state obligations. The actual asset retirement costs related to the CCR rule requirements may vary substantially from the estimates used to record the ARO due to the uncertainty and evolving nature of the compliance strategies that will be used and the availability of data used to estimate costs, such as the quantity of coal ash present at certain sites and the volume of fill that will be needed to cap and cover certain impoundments. The Company updates its estimates as new information becomes available. The Company expects to seek recovery of any increased costs related to complying with the CCR rule through the ratemaking process. In addition to the above, under a 2018 Administrative Order on Consent and ongoing negotiations with the Montana Department of Ecological Quality, the owners of Colstrip are required to provide financial assurance, primarily in the form of surety bonds, to secure each owner's pro-rata share of various anticipated closure and remediation of the ash ponds and coal holding areas. The amount of financial assurance required of each owner may, like the ARO, vary substantially due to the uncertainty and evolving nature of anticipated closure and remediation activities, and as those activities are completed over time. The following table documents the changes in the Company’s asset retirement obligation during the years ended December 31 (dollars in thousands): 2022 2021 2020 Asset retirement obligation at beginning of year $ 17,142 $ 17,194 $ 20,338 Liabilities incurred — 825 ( 2,315 ) Liabilities settled ( 1,964 ) ( 1,541 ) ( 1,645 ) Accretion expense 605 664 816 Asset retirement obligation at end of year $ 15,783 $ 17,142 $ 17,194

Pension Plans and Other Postret

Pension Plans and Other Postretirement Benefit Plans	12 Months Ended
	Dec. 31, 2022
Retirement Benefits, Description [Abstract]
Pension Plans and Other Postretirement Benefit Plans	NOTE 12. PENSION PLANS AND OTHE R POSTRETIREMENT BENEFIT PLANS The pension and other postretirement benefit plans described below only relate to Avista Utilities. AEL&P (not discussed below) participates in a defined contribution multiemployer plan for its union workers and a defined contribution money purchase pension plan for its nonunion workers. None of the subsidiary retirement plans, individually or in the aggregate, are significant to Avista Corp. Avista Utilities The Company has a defined benefit pension plan covering the majority of all regular full-time employees at Avista Utilities that were hired prior to January 1, 2014. Employees eligible for the plan continue to accrue benefits. Individual benefits under this plan are based upon the employee’s years of service, date of hire and average compensation as specified in the plan. Non-union employees hired on or after January 1, 2014 participate in a defined contribution 401(k) plan in lieu of a defined benefit pension plan. Union employees hired on or after January 1, 2014 are still covered under the defined benefit pension plan. Effective December 31, 2023, the plan will be closed to new union employees. The Company’s funding policy is to contribute at least the minimum amounts that are required to be funded under the Employee Retirement Income Security Act, but not more than the maximum amounts that are currently deductible for income tax purposes. The Company contributed $ 42.0 million in cash to the pension plan in 2022 and 2021 , and $ 22.0 million in 2020 . The Company expects to contribute $ 10.0 million in cash to the pension plan in 2023. In 2022, the defined benefit pension plan lump sum payments exceeded the annual service and interest costs for the plan. This resulted in a partial settlement of the plan, and the Company recorded a settlement loss of $ 11.8 million for the previously unrecognized losses in the year ended December 31, 2022.This loss was deferred as a regulatory asset. The Company also has a SERP that provides additional pension benefits to certain executive officers and certain key employees of the Company. The SERP is intended to provide benefits to individuals whose benefits under the defined benefit pension plan are reduced due to the application of Section 415 of the Internal Revenue Code of 1986 and the deferral of salary under deferred compensation plans. The liability and expense for this plan are included as pension benefits in the tables included in this Note. The Company expects that benefit payments under the pension plan and the SERP will total (dollars in thousands): 2023 2024 2025 2026 2027 Total 2028- Expected benefit payments $ 41,993 $ 41,759 $ 42,207 $ 42,517 $ 43,037 $ 226,781 The expected long-term rate of return on plan assets is based on past performance and economic forecasts for the types of investments held by the plan. In selecting a discount rate, the Company considers yield rates for highly rated corporate bond portfolios with maturities similar to that of the expected term of pension benefits. The Company provides certain health care and life insurance benefits for eligible retired employees that were hired prior to January 1, 2014. The Company accrues the estimated cost of postretirement benefit obligations during the years that employees provide services. The liability and expense of this plan are included as other postretirement benefits. Non-union employees hired on or after January 1, 2014, will have access to the retiree medical plan upon retirement; however, Avista Corp. will no longer provide a contribution toward their medical premium. The Company has a Health Reimbursement Arrangement (HRA) to provide employees with tax-advantaged funds to pay for allowable medical expenses upon retirement. The amount earned by the employee is fixed on the retirement date based on the employee’s years of service and the ending salary. The liability and expense of the HRA are included as other postretirement benefits. The Company provides death benefits to beneficiaries of executive officers who die during their term of office or after retirement. Under the plan, an executive officer’s designated beneficiary will receive a payment equal to twice the executive officer’s annual base salary at the time of death (or if death occurs after retirement, a payment equal to twice the executive officer’s total annual pension benefit). The liability and expense for this plan are included as other postretirement benefits. The Company expects that benefit payments under other postretirement benefit plans will total (dollars in thousands): 2023 2024 2025 2026 2027 Total 2028- Expected benefit payments $ 7,031 $ 7,234 $ 7,436 $ 7,585 $ 7,771 $ 40,959 The Company expects to contrib ute $ 7.0 million to other postretirement benefit plans in 2023. The Company uses a December 31 measurement date for its pension and other postretirement benefit plans. The following table sets forth the pension and other postretirement benefit plan disclosures as of December 31, 2022 and 2021 and the components of net periodic benefit costs for the years ended December 31, 2022, 2021 and 2020 (dollars in thousands): Pension Benefits Other Post- 2022 2021 2022 2021 Change in benefit obligation: Benefit obligation as of beginning of year $ 799,042 $ 826,915 $ 167,598 $ 161,233 Service cost 23,877 25,306 4,369 4,114 Interest cost 26,536 26,160 5,503 5,139 Actuarial (gain)/loss ( 204,775 ) ( 13,997 ) ( 54,120 ) 2,808 Plan change 3,302 — — — Settlement ( 60,206 ) — — — Benefits paid ( 30,067 ) ( 65,342 ) ( 7,715 ) ( 5,696 ) Benefit obligation as of end of year $ 557,709 $ 799,042 $ 115,635 $ 167,598 Change in plan assets: Fair value of plan assets as of beginning of year $ 750,963 $ 722,024 $ 59,544 $ 52,173 Actual return on plan assets ( 163,866 ) 50,370 ( 10,072 ) 7,371 Employer contributions 42,000 42,000 — — Settlement ( 60,206 ) — — — Benefits paid ( 28,188 ) ( 63,431 ) — — Fair value of plan assets as of end of year $ 540,703 $ 750,963 $ 49,472 $ 59,544 Funded status $ ( 17,006 ) $ ( 48,079 ) $ ( 66,163 ) $ ( 108,054 ) Amounts recognized in the Consolidated Balance Sheets: Other non-current assets $ 13,382 $ — $ — $ — Other current liabilities ( 1,934 ) ( 1,951 ) ( 706 ) ( 684 ) Non-current liabilities ( 28,454 ) ( 46,128 ) ( 65,457 ) ( 107,370 ) Net amount recognized $ ( 17,006 ) $ ( 48,079 ) $ ( 66,163 ) $ ( 108,054 ) Accumulated pension benefit obligation $ 495,654 $ 685,493 Accumulated postretirement benefit obligation: For retirees $ 61,984 $ 78,347 For fully eligible employees $ 19,731 $ 32,144 For other participants $ 33,920 $ 57,107 Included in accumulated other comprehensive loss (income) (net of tax): Unrecognized prior service cost (credit) $ 4,105 $ 1,699 $ ( 1,911 ) $ ( 2,741 ) Unrecognized net actuarial loss 83,794 94,109 13,643 48,872 Total 87,899 95,808 11,732 46,131 Less regulatory asset ( 85,198 ) ( 85,550 ) ( 12,375 ) ( 45,350 ) Accumulated other comprehensive loss for unfunded benefit $ 2,701 $ 10,258 $ ( 643 ) $ 781 Pension Benefits Other Post- 2022 2021 2022 2021 Weighted-average assumptions as of December 31: Discount rate for benefit obligation 6.10 % 3.39 % 6.10 % 3.40 % Discount rate for annual expense 3.39 % 3.25 % 3.40 % 3.27 % Expected long-term return on plan assets 5.80 % 5.40 % 4.70 % 4.60 % Rate of compensation increase 4.69 % 4.66 % Medical cost trend pre-age 65 – initial 6.25 % 6.00 % Medical cost trend pre-age 65 – ultimate 5.00 % 5.00 % Ultimate medical cost trend year pre-age 65 2028 2026 Medical cost trend post-age 65 – initial 6.25 % 6.00 % Medical cost trend post-age 65 – ultimate 5.00 % 5.00 % Ultimate medical cost trend year post-age 65 2028 2026 Pension Benefits Other Post-retirement Benefits 2022 2021 2020 2022 2021 2020 Components of net periodic benefit cost: Service cost (1) $ 23,877 $ 25,306 $ 22,392 $ 4,369 $ 4,114 $ 3,902 Interest cost 26,536 26,160 27,853 5,503 5,139 6,042 Expected return on plan assets ( 43,872 ) ( 39,088 ) ( 34,886 ) ( 2,799 ) ( 2,400 ) ( 2,377 ) Amortization of prior service cost (credit) 257 257 257 ( 1,050 ) ( 921 ) ( 958 ) Net loss recognition 4,180 6,645 6,717 3,344 3,865 4,871 Settlement loss (2) 11,828 — — — — — Net periodic benefit cost $ 22,806 $ 19,280 $ 22,333 $ 9,367 $ 9,797 $ 11,480 (1) Total service costs in the table above are recorded to the same accounts as labor expense. Labor and benefits expense is recorded to various projects based on whether the work is a capital project or an operating expense. Approximately 40 percent of all labor and benefits is capitalized to utility property and 60 percent is expensed to utility other operating expenses. (2) The settlement loss was deferred as a regulatory asset to be amortized over future periods. Plan Assets The Finance Committee of the Company’s Board of Directors approves investment policies, objectives and strategies that seek an appropriate return for the pension plan and other postretirement benefit plans and reviews and approves changes to the investment and funding policies. The Company has contracted with investment consultants who are responsible for monitoring the individual investment managers. The investment managers’ performance and related individual fund performance is periodically reviewed by an internal benefits committee and by the Finance Committee to monitor compliance with investment policy objectives and strategies. Pension plan assets are invested in mutual funds, trusts and partnerships that hold marketable debt and equity securities, real estate, and absolute return. In seeking to obtain a return that aligns with the funded status of the pension plan, the investment consultant recommends allocation percentages by asset classes. These recommendations are reviewed by the internal benefits committee, which then recommends their adoption by the Finance Committee. The Finance Committee has established target investment allocation percentages by asset classes and also investment ranges for each asset class. The target investment allocation percentages are typically the midpoint of the established range. The target investment allocation percentages by asset classes are indicated in the table below: 2022 2021 Equity securities 55 % 55 % Debt securities 40 % 40 % Real estate 5 % 5 % Absolute return 0 % 0 % The target investment allocation percentages were revised in the first quarter of 2021 and the pension plan assets were reinvested to move toward the new target investment allocation percentages. The target asset allocation percentages were modified to better align the asset allocations with the funded status of the pension plan. The fair value of pension plan assets invested in debt and equity securities was based primarily on fair value (market prices). The fair value of investment securities traded on a national securities exchange is determined based on the reported last sales price; securities traded in the over-the-counter market are valued at the last reported bid price. Investment securities for which market prices are not readily available or for which market prices do not represent the value at the time of pricing, the investment manager estimates fair value based upon other inputs (including valuations of securities that are comparable in coupon, rating, maturity and industry). Pension plan and other postretirement plan assets with fair values are measured using net asset value (NAV) are excluded from the fair value hierarchy and included as reconciling items in the tables below. The plan's investments in common/collective trusts have redemption limitations that permit quarterly redemptions following notice requirements of 45 to 60 days. Most of the plan's investments in closely held investments and partnership interests have redemption limitations that range from bi-monthly to semi-annually following redemption notice requirements of 60 to 90 days. The following table discloses by level within the fair value hierarchy (see Note 18 for a description of the fair value hierarchy) of the pension plan’s assets measured and reported as of December 31, 2022 at fair value (dollars in thousands): Level 1 Level 2 Level 3 Total Cash equivalents $ — $ 5,110 $ — $ 5,110 Fixed income securities: U.S. government issues — 16,732 — 16,732 Corporate issues — 161,180 — 161,180 International issues — 23,108 — 23,108 Municipal issues — 13,427 — 13,427 Mutual funds: U.S. equity securities 154,442 — — 154,442 International equity securities 58,933 — — 58,933 Plan assets measured at NAV (not subject to hierarchy Common/collective trusts: Real estate — — — 30,406 Partnership/closely held investments: International equity securities — — — 69,792 Real estate — — — 7,573 Total $ 213,375 $ 219,557 $ — $ 540,703 The following table discloses by level within the fair value hierarchy (see Note 18 for a description of the fair value hierarchy) of the pension plan’s assets measured and reported as of December 31, 2021 at fair value (dollars in thousands): Level 1 Level 2 Level 3 Total Cash equivalents $ — $ 6,259 $ — $ 6,259 Fixed income securities: U.S. government issues — 19,310 — 19,310 Corporate issues — 233,496 — 233,496 International issues — 34,270 — 34,270 Municipal issues — 18,558 — 18,558 Mutual funds: U.S. equity securities 236,552 — — 236,552 International equity securities 112,873 — — 112,873 Plan assets measured at NAV (not subject to hierarchy Common/collective trusts: Real estate — — — 31,040 Partnership/closely held investments: Absolute return — — — 363 International equity securities — — — 50,427 Real estate — — — 7,815 Total $ 349,425 $ 311,893 $ — $ 750,963 The fair value of other postretirement plan assets invested in debt and equity securities was based primarily on market prices. The fair value of investment securities traded on a national securities exchange is determined based on the last reported sales price; securities traded in the over-the-counter market are valued at the last reported bid price. For investment securities for which market prices are not readily available, the investment manager determines fair value based upon other inputs (including valuations of securities that are comparable in coupon, rating, maturity and industry). The target asset allocation was 60 percent equity securities and 40 percent debt securities in both 2022 and 2021. The fair value of other postretirement plan assets was determined as of December 31, 2022 and 2021. The following table discloses by level within the fair value hierarchy (see Note 18 for a description of the fair value hierarchy) of other postretirement plan assets measured and reported as of December 31, 2022 at fair value (dollars in thousands): Level 1 Level 2 Level 3 Total Balanced index mutual fund (1) $ 49,472 $ — $ — $ 49,472 The following table discloses by level within the fair value hierarchy (see Note 18 for a description of the fair value hierarchy) of other postretirement plan assets measured and reported as of December 31, 2021 at fair value (dollars in thousands): Level 1 Level 2 Level 3 Total Balanced index mutual fund (1) $ 59,545 $ — $ — $ 59,545 (1) The balanced index fund for 2022 and 2021 is a single mutual fund that includes a percentage of U.S. equity and fixed income securities and International equity and fixed income securities. 401(k) Plans and Executive Deferral Plan Avista Utilities has a salary deferral 401(k) plan that is a defined contribution plan and covers substantially all employees. Employees can make contributions to their respective accounts in the plans on a pre-tax basis up to the maximum amount permitted by law. The Company matches a portion of the salary deferred by each participant according to the schedule in the respective plan. Employer matching contributions were as follows for the years ended December 31 (dollars in thousands): 2022 2021 2020 Employer 401(k) matching contributions $ 13,258 $ 11,671 $ 11,742 The Company has an Executive Deferral Plan. This plan allows executive officers and other key employees the opportunity to defer until the earlier of their retirement, termination, disability or death, up to 75 percent of their base salary and/or up to 100 percent of their incentive payments. Deferred compensation funds are held by the Company in a Rabbi Trust. There were deferred compensation assets included in other property and investments-net and corresponding deferred compensation liabilities included in other non-current liabilities and deferred credits on the Consolidated Balance Sheets of the following amounts as of December 31 (dollars in thousands): 2022 2021 Deferred compensation assets and liabilities $ 7,541 $ 9,513

Accounting For Income Taxes

Accounting For Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Accounting for Income Taxes	NOTE 13. ACCOUNTIN G FOR INCOME TAXES Income Tax Expense Income tax expense consisted of the following for the years ended December 31 (dollars in thousands): 2022 2021 2020 Current income tax expense (benefit) $ 1,040 $ 807 $ ( 37,913 ) Deferred income tax expense (benefit) ( 18,231 ) 11,224 44,964 Total income tax expense (benefit) $ ( 17,191 ) $ 12,031 $ 7,051 State income taxes are not a significant portion of total income tax expense. A reconciliation of federal income taxes derived from the statutory federal tax rate of 21 percent applied to income before income taxes is as follows for the years ended December 31 (dollars in thousands): 2022 2021 2020 Federal income taxes at statutory rates $ 28,977 21.0 % $ 33,467 21.0 % $ 28,673 21.0 % Increase (decrease) in tax resulting from: Tax effect of regulatory treatment of utility ( 12,366 ) ( 9.0 ) ( 13,820 ) ( 8.7 ) ( 12,893 ) ( 9.4 ) State income tax expense 1,676 1.2 1,385 0.8 814 0.6 Flow through related to deduction of meters ( 34,454 ) ( 25.0 ) ( 8,678 ) ( 5.4 ) — — Non-plant excess deferred turnaround (3) — — — — ( 8,476 ) ( 6.2 ) Customer refunds related to prior years at 35 percent — — — — ( 1,189 ) ( 0.9 ) Other ( 1,024 ) ( 0.7 ) ( 323 ) ( 0.2 ) 122 0.1 Total income tax expense (benefit) $ ( 17,191 ) ( 12.5 )% $ 12,031 7.5 % $ 7,051 5.2 % (1) Prior to 2022, for the depreciation-related temporary differences under the normalization tax accounting method, the Company utilized the average rate assumption method to compute the amounts returned to customers. Beginning in 2022, the Company changed to the alternative method, to be in compliance with recently released revenue procedures and private letter rulings. (2) During 2021 and 2022, new rates from the Company's Idaho, Oregon and Washington general rate cases went into effect with base rate increases offset by customer tax credits. As the customer tax credits are returned to customers, this results in a decrease to income tax expense as a result of flowing through the benefits related to meters and mixed service costs. This decrease in income tax expense offsets the increases in base rate granted to the Company in these general rate cases. (3) As part of a settlement agreement in a Washington general rate case, the parties agreed to utilize $ 10.9 million ($ 8.4 million when tax-effected) of the electric benefits to offset costs associated with accelerating the depreciation of Colstrip, to reflect a remaining useful life through December 31, 2025. Deferred Income Taxes Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes and tax credit carryforwards. The total net deferred income tax liability consisted of the following as of December 31 (dollars in thousands): 2022 2021 Deferred income tax assets: Regulatory liabilities $ 197,998 $ 200,513 Tax credits and NOL carryforwards 74,782 64,994 Provisions for pensions 20,132 25,650 Other 54,903 38,181 Total gross deferred income tax assets 347,815 329,338 Valuation allowances for deferred tax assets ( 3,874 ) ( 9,626 ) Total deferred income tax assets after valuation allowances 343,941 319,712 Deferred income tax liabilities: Utility property, plant, and equipment 712,470 688,856 Regulatory assets 281,483 264,978 Other 24,983 8,587 Total deferred income tax liabilities 1,018,936 962,421 Net long-term deferred income tax liability $ 674,995 $ 642,709 The realization of deferred income tax assets is dependent upon the ability to generate taxable income in future periods. The Company evaluated available evidence supporting the realization of its deferred income tax assets and determined it is more likely than not that deferred income tax assets will be realized. As of December 31, 2022 , the Company had $ 13.6 million of state tax credit carryforwards. Of the total amount, the Company believes that it is more likely than not that it will only be able to utilize $ 9.7 million of the state tax credits. As such, the Company has recorded a valuation allowance of $ 3.9 million against the state tax credit carryforwards and reflected the net amount of $ 9.7 million as an asset as of December 31, 2022. State tax credits expire from 2023 to 2036 . Status of Internal Revenue Service (IRS) and State Examinations The Company and its eligible subsidiaries file consolidated federal income tax returns. All tax years after 2018 are open for an IRS tax examination. The Company also files state income tax returns in certain jurisdictions, including Idaho, Oregon, Montana and Alaska. Subsidiaries are charged or credited with the tax effects of their operations on a stand-alone basis. All tax years after 2018 are open for examination in Idaho, Oregon, Montana and Alaska. The Company believes that any open tax years for federal or state income taxes will not result in adjustments that would be significant to the consolidated financial statements.

Energy Purchase Contracts

Energy Purchase Contracts	12 Months Ended
	Dec. 31, 2022
Energy Purchase Contracts [Abstract]
Energy Purchase Contracts	NOTE 14. ENERGY P URCHASE CONTRACTS The below discussion only relates to Avista Utilities. The sole energy purchase contract at AEL&P is a PPA for the Snettisham hydroelectric project and it is accounted for as a lease. AEL&P does not have any other significant operating agreements or contractual obligations. See Note 5 for further discussion of the Snettisham PPA. Avista Utilities has contracts for the purchase of fuel for thermal generation, natural gas for resale and various agreements for the purchase or exchange of electric energy with other entities. The remaining term of the contracts range from one month to twenty-five years . Total expenses for power purchased, natural gas purchased, fuel for generation and other fuel costs, which are included in utility resource costs in the Consolidated Statements of Income, were as follows for the years ended December 31 (dollars in thousands): 2022 2021 2020 Utility power resources $ 660,967 $ 431,199 $ 324,297 The following table details Avista Utilities’ future contractual commitments for power resources (including transmission contracts) and natural gas resources (including transportation contracts) (dollars in thousands): 2023 2024 2025 2026 2027 Thereafter Total Power resources $ 245,169 $ 215,044 $ 240,214 $ 214,747 $ 185,590 $ 2,333,955 $ 3,434,719 Natural gas resources 130,921 79,366 39,192 28,046 38,591 320,377 636,493 Total $ 376,090 $ 294,410 $ 279,406 $ 242,793 $ 224,181 $ 2,654,332 $ 4,071,212 These energy purchase contracts were entered into as part of Avista Utilities’ obligation to serve its retail electric and natural gas customers’ energy requirements, including contracts entered into for resource optimization. These costs are recovered either through base retail rates or adjustments to retail rates as part of the power and natural gas cost deferral and recovery mechanisms. The future contractual commitments for power resources include fixed contractual amounts related to the Company's contracts with PUDs to purchase portions of the output of certain generating facilities. Although Avista Utilities has no investment in the PUD generating facilities, the contracts obligate Avista Utilities to pay certain minimum amounts whether or not the facilities are operating. The cost of power obtained under the contracts, including payments made when a facility is not operating, is included in utility resource costs in the Consolidated Statements of Income. The contractual amounts included above consist of Avista Utilities’ share of existing debt service cost and its proportionate share of the variable operating expenses of these projects. The minimum amounts payable under these contracts are based in part on the proportionate share of the debt service requirements of the PUD's revenue bonds for which the Company is indirectly responsible. The Company's total future debt service obligation associated with the revenue bonds outstanding at December 31, 2022 (principal and interest) was $ 281.0 million. In addition, Avista Utilities has operating agreements, settlements and other contractual obligations related to its generating facilities and transmission and distribution services. The expenses associated with these agreements are reflected as other operating expenses in the Consolidated Statements of Income. The following table details future contractual commitments under these agreements (dollars in thousands): 2023 2024 2025 2026 2027 Thereafter Total Contractual obligations $ 30,562 $ 31,416 $ 32,255 $ 16,937 $ 17,343 $ 178,193 $ 306,706

Short-Term Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2022
Short-Term Debt [Abstract]
Short-Term Borrowings	NOTE 15. S HORT-TERM BORROWINGS Avista Corp. Lines of Credit Avista Corp. has a committed line of credit in the total amount of $ 400 million. with expiration date of June 2026 . The Company has the option to extend for an additional one year period (subject to customary conditions). The committed line of credit is secured by non-transferable first mortgage bonds of the Company issued to the agent bank that would only become due and payable in the event, and then only to the extent, that the Company defaults on its obligations under the committed line of credit. In November 2022, the Company entered into a revolving credit agreement in the amount of $ 50 million with a maturity date in November 2023 . In December 2022, the Company amended the agreement to add an additional $ 50 million, bringing the new aggregate total amount to $ 100 million. Balances outstanding and interest rates of borrowings (excluding letters of credit) under the Company’s $ 400 million revolving committed line of credit due in June 2026 were as follows as of December 31 (dollars in thousands): 2022 2021 Balance outstanding at end of period $ 313,000 $ 284,000 Letters of credit outstanding at end of period 35,563 34,000 Average interest rate at end of period 5.31 % 1.11 % As of December 31, 2022 , the Company did no t have any outstanding borrowings under the $ 100 million revolving credit agreement due in November 2023. As of December 31, 2022 and 2021, the borrowings outstanding under Avista Corp.'s committed lines of credit were classified as short-term borrowings on the Consolidated Balance Sheets. 2022 Term Loan In December 2022, the Company entered into a term loan agreement in the amount of $ 100 million with a maturity date of March 30, 2023 . The initial agreement included an option to add an additional $ 50 million in principal as an incremental facility, which the company exercised in December 2022, bringing the total aggregate amount to $ 150 million. The Company borrowed the entire $ 150 million available under the agreement. The borrowings outstanding under this agreement were classified as short-term borrowings on the Consolidated Balance Sheets. 2022 Letter of Credit Facility In December 2022, the Company entered into a continuing letter of credit a greement in the aggregate amount of $ 50 million. Either party may terminate the agreement at any time. As of December 31, 2022 , the Company had $ 18.5 million in letters of credit outstanding under this agreement. Letters of credit are not reflected on the Consolidated Balance Sheets. If a letter of credit were drawn upon by the holder, we would have an immediate obligation to reimburse the bank that issued that letter. Covenants and Default Provisions The short-term borrowing agreements contain customary covenants and default provisions, including a change in control (as defined in the agreements). The events of default under each of the credit facilities also include a cross default from other indebtedness (as defined) and in some cases other obligations. Most of the short-term borrowing agreement also include a covenant which does not permit the ratio of “consolidated total debt” to “consolidated total capitalization” of Avista Corp. to be greater than 65 percent at any time. As of December 31, 2022, the Company was in compliance with this covenant. AEL&P AEL&P has a committed line of credit in the amount of $ 25.0 million that expires in November 2024 . The committed line of credit is secured by non-transferable first mortgage bonds of AEL&P issued to the agent bank that would only become due and payable in the event, and then only to the extent, that AEL&P defaults on its obligations under the committed line of credit. The committed line of credit agreement contains customary covenants and default provisions. The credit agreement has a covenant which does not permit the ratio of “consolidated total debt at AEL&P” to “consolidated total capitalization at AEL&P,” including the impact of the Snettisham bonds to be greater than 67.5 percent at any time. As of December 31, 2022, AEL&P was in compliance with this covenant. As of December 31, 2022, and 2021 there were no borrowings under the AEL&P committed line of credit.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Long-Term Debt	NOTE 16. LON G-TERM DEBT The following details long-term debt outstanding as of December 31 (dollars in thousands): Maturity Description Interest 2022 2021 Avista Corp. Secured Long-Term Debt 2022 First Mortgage Bonds 5.13 % $ — $ 250,000 2023 Secured Medium-Term Notes 7.18 %- 7.54 % 13,500 13,500 2028 Secured Medium-Term Notes 6.37 % 25,000 25,000 2032 Secured Pollution Control Bonds (1) (1) 66,700 66,700 2034 Secured Pollution Control Bonds (1) (1) 17,000 17,000 2035 First Mortgage Bonds 6.25 % 150,000 150,000 2037 First Mortgage Bonds 5.70 % 150,000 150,000 2040 First Mortgage Bonds 5.55 % 35,000 35,000 2041 First Mortgage Bonds 4.45 % 85,000 85,000 2044 First Mortgage Bonds 4.11 % 60,000 60,000 2045 First Mortgage Bonds 4.37 % 100,000 100,000 2047 First Mortgage Bonds 4.23 % 80,000 80,000 2047 First Mortgage Bonds 3.91 % 90,000 90,000 2048 First Mortgage Bonds 4.35 % 375,000 375,000 2049 First Mortgage Bonds 3.43 % 180,000 180,000 2050 First Mortgage Bonds 3.07 % 165,000 165,000 2051 First Mortgage Bonds 3.54 % 175,000 175,000 2051 First Mortgage Bonds 2.90 % 140,000 140,000 2052 First Mortgage Bonds (2) 4.00 % 400,000 — Total Avista Corp. secured long-term debt 2,307,200 2,157,200 Alaska Electric Light and Power Company Secured Long-Term Debt 2044 First Mortgage Bonds 4.54 % 75,000 75,000 Total secured long-term debt 2,382,200 2,232,200 Alaska Energy and Resources Company Unsecured Long-Term Debt 2024 Unsecured Term Loan 3.44 % 15,000 15,000 Total secured and unsecured long-term debt 2,397,200 2,247,200 Other Long-Term Debt Components Unamortized debt discount ( 726 ) ( 632 ) Unamortized long-term debt issuance costs ( 18,261 ) ( 14,498 ) Total 2,378,213 2,232,070 Secured Pollution Control Bonds held by Avista ( 83,700 ) ( 83,700 ) Current portion of long-term debt ( 13,500 ) ( 250,000 ) Total long-term debt $ 2,281,013 $ 1,898,370 (1) In December 2010, $ 66.7 million and $ 17.0 million of the City of Forsyth, Montana Pollution Control Revenue Refunding Bonds (Avista Corporation Colstrip Project) due in 2032 and 2034, respectively, which had been held by Avista Corp. since 2008 and 2009, respectively, were refunded by new variable rate bond issues. The new bonds were not offered to the public and were purchased by Avista Corp. due to market conditions. The Company has the ability to remarket these bonds to unaffiliated investors at a later date, subject to market conditions. So long as Avista Corp. is the holder of these bonds, the bonds will not be reflected as an asset or a liability on the Consolidated Balance Sheets. (2) In March 2022, the Company issued and sold $ 400.0 million of 4.00 percent first mortgage bonds due in 2052 through a public offering. The total net proceeds from the sale of the bonds were used to repay the borrowings outstanding under Avista Corp.'s $ 400.0 million committed line of credit, as well as $ 250.0 million of maturing debt. In connection with the pricing of the first mortgage bonds in March 2022, the Company cash settled thirteen interest rate swap derivatives (notional aggregate amount of $ 140.0 million) and paid a net amount of $ 17.0 million. See Note 8 for a discussion of interest rate swap derivatives. The following table details future long-term debt maturities including long-term debt to affiliated trusts (see Note 17) (dollars in thousands): 2023 2024 2025 2026 2027 Thereafter Total Debt maturities $ 13,500 $ 15,000 $ — $ — $ — $ 2,336,547 $ 2,365,047 Substantially all of Avista Utilities' and AEL&P's owned properties are subject to the lien of their respective mortgage indentures. Under the Mortgages and Deeds of Trust (Mortgages) securing their first mortgage bonds (including secured medium-term notes), Avista Utilities and AEL&P may each issue additional first mortgage bonds under their specific mortgage in an aggregate principal amount equal to the sum of: • 66-2/3 percent of the cost or fair value (whichever is lower) of property additions of that entity which have not previously been made the basis of any application under that entity's Mortgage, or • an equal principal amount of retired first mortgage bonds of that entity which have not previously been made the basis of any application under that entity's Mortgage, or • deposit of cash. Avista Utilities and AEL&P may not individually issue any additional first mortgage bonds (with certain exceptions in the case of bonds issued on the basis of retired bonds) unless the particular entity issuing the bonds has “net earnings” (as defined in that entity's Mortgage) for any period of 12 consecutive calendar months out of the preceding 18 calendar months that were at least twice the annual interest requirements on all mortgage securities at the time outstanding, including the first mortgage bonds to be issued, and on all indebtedness of prior rank. As of December 31, 2022, property additions and retired bonds would have allowed, and the net earnings test would not have prohibited, the issuance of $ 1.4 billion in an aggregate principal amount of additional first mortgage bonds at Avista Utilities and $ 40.4 million by AEL&P, at an assumed interest rate of 8 percent in e ach case.

Long-Term Debt to Affiliated Tr

Long-Term Debt to Affiliated Trusts	12 Months Ended
	Dec. 31, 2022
Long Term Debt To Affiliated Trust [Abstract]
Long-Term Debt To Affiliated Trusts	NOTE 17. LONG-TERM DEB T TO AFFILIATED TRUSTS In 1997 , the Company issued Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B, with a principal amount of $ 51.5 million to Avista Capital II, an affiliated business trust formed by the Company. Avista Capital II issued $ 50.0 million of Preferred Trust Securities with a floating distribution rate of the London interbank offered rate ( LIBOR ) plus 0.875 percent, calculated and reset quarterly. Effective on July 3, 2023, the reference to LIBOR in the formulation for the distribution rate on these securities will be replaced, by operation of law, with three-month CME Term Secured Overnight Financing Rate (SOFR), as calculated and published by CME Group Benchmark Administration, Ltd. (a successor administrator), plus a tenor spread adjustment of 0.26161 . Accordingly, the distribution rate on the Preferred Trust Securities will then be three-month CME Term SOFR plus 1.13661 percent. The distribution rates paid were as follows during the years ended December 31: 2022 2021 2020 Low distribution rate 1.05 % 0.99 % 1.10 % High distribution rate 5.64 % 1.10 % 2.79 % Distribution rate at the end of the year 5.64 % 1.05 % 1.10 % Concurrent with the issuance of the Preferred Trust Securities, Avista Capital II issued $ 1.5 million of Common Trust Securities to the Company. These Preferred Trust Securities may be redeemed at the option of Avista Capital II at any time and mature on June 1, 2037. In December 2000, the Company purchased $ 10.0 million of these Preferred Trust Securities. The Company owns 100 percent of Avista Capital II and has solely and unconditionally guaranteed the payment of distributions on, and redemption price and liquidation amount for, the Preferred Trust Securities to the extent that Avista Capital II has funds available for such payments from the respective debt securities. Upon maturity or prior redemption of such debt securities, the Preferred Trust Securities will be mandatorily redeemed. The Company does not include these capital trusts in its consolidated financial statements as Avista Corp. is not the primary beneficiary. As such, the sole assets of the capital trusts are $ 51.5 million of junior subordinated deferrable interest debentures of Avista Corp., which are reflected on the Consolidated Balance Sheets. Interest expense to affiliated trusts in the Consolidated Statements of Income represents interest expense on these debentures.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value	NOTE 18. F AIR VALUE The carrying values of cash and cash equivalents, accounts and notes receivable, accounts payable and short-term borrowings are reasonable estimates of their fair values. Long-term debt (including current portion), finance leases, and long-term debt to affiliated trusts are reported at carrying value on the Consolidated Balance Sheets. The fair value hierarchy prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to fair values derived from unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are defined as follows: Level 1 – Quoted prices are available in active markets for identical assets or liabilities. Active markets are those in which transactions for the asset or liability occur with sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 – Pricing inputs are other than quoted prices in active markets included in Level 1, but which are either directly or indirectly observable as of the reporting date. Level 2 includes those financial instruments that are valued using models or other valuation methodologies. These models are primarily industry-standard models that consider various assumptions, including quoted forward prices for commodities, time value, volatility factors, and current market and contractual prices for the underlying instruments, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace throughout the full term of the instrument, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace. Level 3 – Pricing inputs include significant inputs that are generally unobservable from objective sources. These inputs may be used with internally developed methodologies that result in management’s best estimate of fair value. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement requires judgment, and may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels. The determination of the fair values incorporates various factors that not only include the credit standing of the counterparties involved and the impact of credit enhancements (such as cash deposits and letters of credit), but also the impact of Avista Corp.’s nonperformance risk on its liabilities. The following table sets forth the carrying value and estimated fair value of the Company’s financial instruments not reported at estimated fair value on the Consolidated Balance Sheets as of December 31 (dollars in thousands): 2022 2021 Carrying Estimated Carrying Estimated Long-term debt (Level 2) $ 1,113,500 $ 966,881 $ 963,500 $ 1,157,651 Long-term debt (Level 3) 1,200,000 881,480 1,200,000 1,366,619 Snettisham finance lease obligation (Level 3) 45,730 41,700 48,815 54,000 Long-term debt to affiliated trusts (Level 3) 51,547 42,836 51,547 43,299 These estimates of fair value of long-term debt and long-term debt to affiliated trusts were primarily based on available market information, which generally consists of estimated market prices from third party brokers for debt with similar risk and terms. The price ranges obtained from the third party brokers consisted of par values of 60.16 to 103.85 , where a par value of 100.00 represents the carrying value recorded on the Consolidated Balance Sheets. Level 2 long-term debt represents publicly issued bonds with quoted market prices; however, due to their limited trading activity, they are classified as Level 2 because brokers must generate quotes and make estimates using comparable debt with similar risk and terms if there is no trading activity near a period end. Level 3 long-term debt consists of private placement bonds and debt to affiliated trusts, which typically have no secondary trading activity. Fair values in Level 3 are estimated based on market prices from third party brokers using secondary market quotes for debt with similar risk and terms to generate quotes for Avista Corp. bonds. Due to the unique nature of the Snettisham finance lease obligation, the estimated fair value of these items was determined based on a discounted cash flow model using available market information. The Snettisham finance lease obligation was discounted to present value using the Morgan Markets A Ex-Fin discount rate as published on December 31, 2022. The following table discloses by level within the fair value hierarchy the Company’s assets and liabilities measured and reported on the Consolidated Balance Sheets as of December 31, 2022 at fair value on a recurring basis (dollars in thousands): Level 1 Level 2 Level 3 Counterparty Total December 31, 2022 Assets: Energy commodity derivatives (2) $ — $ 146,232 $ 288 $ ( 136,605 ) $ 9,915 Foreign currency exchange derivatives — 43 — — 43 Interest rate swap derivatives — 11,184 — — 11,184 Equity investments (3) — — 54,284 — 54,284 Deferred compensation assets: Mutual Funds: Fixed income securities (3) 1,267 — — — 1,267 Equity securities (3) 6,132 — — — 6,132 Total $ 7,399 $ 157,459 $ 54,572 $ ( 136,605 ) $ 82,825 Liabilities: Energy commodity derivatives (2) $ — $ 258,769 $ 18,022 $ ( 242,044 ) $ 34,747 Foreign currency exchang e derivatives — 3 — — 3 Interest rate swap derivatives — 52 — — 52 Total $ — $ 258,824 $ 18,022 $ ( 242,044 ) $ 34,802 The following table discloses by level within the fair value hierarchy the Company’s assets and liabilities measured and reported on the Consolidated Balance Sheets as of December 31, 2021 at fair value on a recurring basis (dollars in thousands): Level 1 Level 2 Level 3 Counterparty Total December 31, 2021 Assets: Energy commodity derivatives (2) $ — $ 34,119 $ 143 $ ( 31,354 ) $ 2,908 Interest rate swap derivatives — 2,319 — ( 1,170 ) 1,149 Deferred compensation assets: Mutual Funds: Fixed income securities (3) 1,809 — — — 1,809 Equity securities (3) 7,594 — — — 7,594 Total $ 9,403 $ 36,438 $ 143 $ ( 32,524 ) $ 13,460 Liabilities: Energy commodity derivatives (2) $ — $ 41,733 $ 7,914 $ ( 40,443 ) $ 9,204 Foreign currency exchange derivatives — 19 — — 19 Interest rate swap derivatives — 25,274 — ( 1,170 ) 24,104 Total $ — $ 67,026 $ 7,914 $ ( 41,613 ) $ 33,327 (1) The Company is permitted to net derivative assets and derivative liabilities with the same counterparty when a legally enforceable master netting agreement exists. In addition, the Company nets derivative assets and derivative liabilities against any payables and receivables for cash collateral held or placed with these same counterparties. (2) The level 3 energy commodity derivative balances are associated with natural gas exchange agreements (3) These assets are included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets. The difference between the amount of derivative assets and liabilities disclosed in respective levels in the table above and the amount of derivative assets and liabilities disclosed on the Consolidated Balance Sheets is due to netting arrangements with certain counterparties. See Note 8 for additional discussion of derivative netting. To establish fair value for energy commodity derivatives, the Company uses quoted market prices and forward price curves to estimate the fair value of energy commodity derivative instruments included in Level 2. In particular, electric derivative valuations are performed using market quotes, adjusted for periods in between quotable periods. Natural gas derivative valuations are estimated using New York Mercantile Exchange pricing for similar instruments, adjusted for basin differences, using market quotes. Where observable inputs are available for substantially the full term of the contract, the derivative asset or liability is included in Level 2. To establish fair values for interest rate swap derivatives, the Company uses forward market curves for interest rates for the term of the swaps and discounts the cash flows back to present value using an appropriate discount rate. The discount rate is calculated by third party brokers according to the terms of the swap derivatives and evaluated by the Company for reasonableness, with consideration given to the potential non-performance risk by the Company. Future cash flows of the interest rate swap derivatives are equal to the fixed interest rate in the swap compared to the floating market interest rate multiplied by the notional amount for each period. To establish fair value for foreign currency derivatives, the Company uses forward market curves for Canadian dollars against the US dollar and multiplies the difference between the locked-in price and the market price by the notional amount of the derivative. Forward foreign currency market curves are provided by third party brokers. The Company's credit spread is factored into the locked-in price of the foreign exchange contracts. Deferred compensation assets and liabilities represent funds held by the Company in a Rabbi Trust for an executive deferral plan. These funds consist of actively traded equity and bond funds with quoted prices in active markets. Level 3 Fair Value Natural Gas Exchange Agreement For the natural gas commodity exchange agreement, the Company uses the same Level 2 brokered quotes described above; however, the Company also estimates the purchase and sales volumes (within contractual limits) as well as the timing of those transactions. Changing the timing of volume estimates changes the timing of purchases and sales, impacting which brokered quote is used. Because the brokered quotes can vary significantly from period to period, the unobservable estimates of the timing and volume of transactions can have a significant impact on the calculated fair value. The Company currently estimates volumes and timing of transactions based on a most likely scenario using historical data. Historically, the timing and volume of transactions have not been highly correlated with market prices and market volatility. The following table presents the quantitative information which was used to estimate the fair values of the Level 3 assets and liabilities above as of December 31, 2022 (dollars in thousands): Fair Value (Net) at December 31, 2022 Valuation Technique Unobservable Input Range Natural gas exchange $ ( 17,734 ) Internally derived Forward purchase prices $ 2.89 - $ 4.19 /mmBTU 3.47 Weighted Average Forward sales prices $ 3.11 - $ 23.47 /mmBTU 8.88 Weighted Average Purchase volumes 140,000 - 370,000 mmBTUs Sales volumes 75,000 - 310,000 mmBTUs The valuation methods, significant inputs and resulting fair values described above were developed by the Company's management and are reviewed on at least a quarterly basis to ensure they provide a reasonable estimate of fair value each reporting period. Equity Investments The Company has two equity investments measured at fair value on a recurring basis. For one investment, fair value is determined using a market approach, starting with enterprise values from recent market transaction data for comparable companies with similar equity instruments. The market transaction data was used to estimate an enterprise value of the underlying investment and that value was allocated to the various classes of equity via an option pricing model and a waterfall approach. The selection of appropriate comparable companies and the expected time to a liquidation event requires management judgment. The significant assumptions in the analysis include the comparable market transactions and related enterprise values, time to liquidity event and the market discount for lack of liquidity. For the second investment, the fair value is determined using an income approach utilizing a discounted cash flow model. The model is based on income statement forecasts from the underlying company to determine cash flows for the period of ownership. The model then utilizes market multiples from publicly traded comparable companies in similar industries and projects to estimate the terminal fair value. The market multiples are reduced to reflect the difference in the life cycle between the publicly traded comparable companies and the start-up nature of the investment company. The selection of appropriate comparable companies, market multiples and the reduction to those market multiples requires management judgment. The significant assumptions in the model include the discount rate representing the risk associated with the investment, market multiples and the related reduction to those multiples, revenue forecasts, and the estimated terminal date for the investment. The following table presents the quantitative information which was used to estimate the fair values of the Level 3 equity investments as of December 31, 2022 (dollars in thousands): Fair Value at December 31, 2022 Valuation Technique Unobservable Input Range Equity investments $ 54,284 Market approach Comparable enterprise values $ 130,000 -$ 388,600 246,000 Average Time to liquidity event 2 years Marketability discount 30 % Discounted cash flows Revenue market multiples 1.44 x to 6.55 x Revenue 2.88 x Average Market multiple reduction 30 % to 50 % 40 % Average Discount rate 25 % Revenue market multiples $ 4,000 -$ 337,000 Terminal date 2024 The following table presents activity for assets and liabilities measured at fair value using significant unobservable inputs (Level 3) for the years ended December 31 (dollars in thousands): Natural Gas Exchange Agreement (1) Equity Investments Total Year ended December 31, 2022: Balance as of January 1, 2022 $ ( 7,771 ) $ — $ ( 7,771 ) Transfers in (2) — 20,902 20,902 Total gains or (losses) (realized/unrealized): Included in regulatory assets ( 4,740 ) — ( 4,740 ) Recognized in net income — 33,382 33,382 Settlements ( 5,223 ) — ( 5,223 ) Ending balance as of December 31, 2022 $ ( 17,734 ) $ 54,284 $ 36,550 Year ended December 31, 2021: Balance as of January 1, 2021 $ ( 8,410 ) $ — $ ( 8,410 ) Total gains or (losses) (realized/unrealized): Included in regulatory assets 4,292 — 4,292 Settlements ( 3,653 ) — ( 3,653 ) Ending balance as of December 31, 2021 $ ( 7,771 ) $ — $ ( 7,771 ) Year ended December 31, 2020: Balance as of January 1, 2020 $ ( 2,976 ) $ — $ ( 2,976 ) Total gains or (losses) (realized/unrealized): Included in regulatory assets ( 4,311 ) — ( 4,311 ) Settlements ( 1,123 ) — ( 1,123 ) Ending balance as of December 31, 2020 $ ( 8,410 ) $ — $ ( 8,410 ) (1) There were no purchases, issuances or transfers from other categories of any derivatives instruments during the periods presented in the table above. (2) The Company elected to account for certain equity investments at recurring fair value in 2022, as such the transfer in represents the value as of the election. See further discussion within Note 7 .

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2022
Stockholders' Equity Note [Abstract]
Common Stock	NOTE 19. C OMMON STOCK The payment of dividends on common stock could be limited by: • certain covenants applicable to preferred stock (when outstanding) contained in the Company’s Restated Articles of Incorporation, as amended (currently there are no preferred shares outstanding), • certain covenants applicable to the Company's outstanding long-term debt and committed line of credit agreements, • the hydroelectric licensing requirements of section 10(d) of the FPA (see Note 1), and • certain requirements under the OPUC approval of the AERC acquisition in 2014. The OPUC's AERC acquisition order requires Avista Utilities to maintain a capital structure of no less than 35 percent common equity (inclusive of short-term debt). This limitation may be revised upon request by the Company with approval from the OPUC. The requirements of the OPUC approval of the AERC acquisition are the most restrictive. Under the OPUC restriction, the amount available for dividends at December 31, 2022 wa s $ 258.6 million. See the Consolidated Statements of Equity for dividends declared in the years 2020 through 2022. The Company has 10 million authorized shares of preferred stock. The Company did no t have any preferred stock outstanding as of December 31, 2022 and 2021. Common Stock Issuances The Company issued common stock in 2022 for total net proceeds of $ 137.8 million. Most of these issuances came through the Company's sales agency agreements under which the sales agents may offer and sell new shares of common stock from time to time. The Company has board and regulatory authority to issue a maximum of 5.6 million shares under these agreements, of wh ich 2.3 million rema in unissued as of December 31, 2022. In 2022, 3.3 million shares were issued under these agreements resulting in total net proceeds of $ 137.2 million.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2022
Accumulated Other Comprehensive Loss [Abstract]
Accumulated Other Comprehensive Loss	NOTE 20. ACCUMULATED O THER COMPREHENSIVE LOSS Accumulated Other Comprehensive Loss Accumulated other comprehensive loss, net of tax, consisted of the following as of December 31 (dollars in thousands): 2022 2021 Unfunded benefit obligation for pensions and other postretirement benefit 547 and $ 2,934 , respectively $ 2,058 $ 11,039 The following table details the reclassifications out of accumulated other comprehensive loss by component for the years ended December 31 (dollars in thousands): Amounts Reclassified from Accumulated Other Details about Accumulated Other Comprehensive Loss Components 2022 2021 2020 Amortization of defined benefit pension items Amortization of net prior service cost (a) $ ( 4,095 ) $ ( 793 ) $ ( 794 ) Amortization of net loss (a) 57,650 38,070 5,586 Adjustment due to effects of regulation (a) ( 42,187 ) ( 33,050 ) ( 10,006 ) Total before tax (b) 11,368 4,227 ( 5,214 ) Tax expense (b) ( 2,387 ) ( 888 ) 1,095 Net of tax (b) $ 8,981 $ 3,339 $ ( 4,119 ) (a) These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 12 for additional details). (b) Description is also the affected line item on the Consolidated Statements of Income

Earnings Per Common Share

Earnings Per Common Share	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Earnings Per Common Share	NOTE 21. EARNINGS PER COMMON SHARE The following table presents the computation of basic and diluted earnings per common share for the years ended December 31 (dollars and shares in thousands, except per share amounts): 2022 2021 2020 Numerator: Net income $ 155,176 $ 147,334 $ 129,488 Denominator: Weighted-average number of common shares outstanding-basic 72,989 69,951 67,962 Effect of dilutive securities: Performance and restricted stock awards 104 134 140 Weighted-average number of common shares outstanding-diluted 73,093 70,085 68,102 Earnings per common share: Basic $ 2.13 $ 2.11 $ 1.91 Diluted $ 2.12 $ 2.10 $ 1.90 There were no shares excluded from the calculation because they were antidilutive.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 22. COMMITMENT S AND CONTINGENCIES In the course of its business, the Company becomes involved in various claims, controversies, disputes and other contingent matters, including the items described in this Note. Some of these claims, controversies, disputes and other contingent matters involve litigation or other contested proceedings. For all such matters, the Company intends to vigorously protect and defend its interests and pursue its rights. However, no assurance can be given as to the ultimate outcome of any particular matter because litigation and other contested proceedings are inherently subject to numerous uncertainties. For matters that affect Avista Utilities’ or AEL&P's operations, the Company intends to seek, to the extent appropriate, recovery of incurred costs through the ratemaking process. Boyds Fire (State of Washington Department of Natural Resources v. Avista) In August 2019, the Company was served with a complaint, captioned “State of Washington Department of Natural Resources v. Avista Corporation,” seeking recovery of up to $ 4.4 million for fire suppression and investigation costs and related expenses incurred in connection with a wildfire that occurred in Ferry County, Washington in August 2018. Specifically, the complaint alleges that the fire, which became known as the “Boyds Fire,” was caused by a dead ponderosa pine tree falling into an overhead distribution line, and that Avista Corp. was negligent in failing to identify and remove the tree before it came into contact with the line. Avista Corp. disputes that the tree in question was the cause of the fire and that it was negligent in failing to identify and remove it. Additional lawsuits have subsequently been filed by private landowners seeking property damages, and holders of insurance subrogation claims seeking recovery of insurance proceeds paid. The lawsuits were filed in the Superior Court of Ferry County, Washington. The Company continues to vigorously defend itself in the litigation. However, at this time the Company is unable to predict the likelihood of an adverse outcome or estimate a range of potential loss in the event of such an outcome. Road 11 Fire In April 2022, Avista Corp. received a notice of claim from property owners seeking damages of $ 5 million in connection with a fire that occurred in Douglas County, Washington, in July 2020. In June 2022, those claimants filed suit in the Superior Court of Douglas County, Washington, seeking unspecified damages. The fire, which was designated as the “Road 11 Fire,” occurred in the vicinity of an Avista Corp. 115kv line, resulting in damage to three overhead transmission structures. The fire occurred during a high wind event and grew to 10,000 acres before being contained. The Company disputes that it is liable for the fire and will vigorously defend itself in the pending legal proceeding; however, at this time the Company is unable to predict the likelihood of an adverse outcome or estimate a range of potential loss in the event of such an outcome. Labor Day Windstorm General In September 2020, a severe windstorm occurred in eastern Washington and northern Idaho. The extreme weather event resulted in customer outages and multiple wildfires in the region. The Company has become aware of instances where, during the course of the storm, otherwise healthy trees and limbs, located in areas outside its maintenance right-of-way, broke under the extraordinary wind conditions and caused damage to its energy delivery system at or near what is believed to be the potential area of origin of a wildfire. Those instances include what has been referred to as: the Babb Road fire (near Malden and Pine City, Washington); the Christensen Road fire (near Airway Heights, Washington); the Mile Marker 49 fire (near Orofino, Idaho); and the Kewa Field Fire (near Colville, Washington). These wildfires covered, in total, more than 25,000 acres. The Company estimates approximately 230 residential, commercial and other structures were impacted. With respect to the Christensen Road Fire, the Mile Marker 49 Fire, and the Kewa Field Fire, the Company’s investigation determined that the primary cause of the fires was extreme high winds. To date, the Company has not found any evidence that the fires were caused by any deficiencies in its equipment, maintenance activities or vegetation management practices. See further discussion below regarding the Babb Road Fire. In addition to the instances identified above, the Company is aware of a 5 -acre fire that occurred in Colfax, Washington, which damaged several residential structures. The Company's investigation determined that the Company's facilities were not involved in the ignition of this fire. The Company’s investigation has found no evidence of negligence with respect to any of the fires, and the Company will vigorously defend itself against any claims for damages that may be asserted against it with respect to the wildfires arising out of the extreme wind event; however, at this time the Company is unable to predict the likelihood of an adverse outcome or estimate a range of potential loss in the event of such an outcome. Babb Road Fire In May 2021 the Company learned that the Washington Department of Natural Resources (DNR) had completed its investigation and issued a report on the Babb Road Fire. The Babb Road fire covered approximately 15,000 acres and destroyed approximately 220 structures. There are no reports of personal injury or death resulting from the fire. The DNR report concluded, among other things, that • the fire was ignited when a branch of a multi-dominant Ponderosa Pine tree was broken off by the wind and fell on an Avista Corp. distribution line; • the tree was located approximately 30 feet from the center of Avista Corp.’s distribution line and approximately 20 feet beyond Avista Corp.’s right-of-way; • the tree showed some evidence of insect damage, damage at the top of the tree from porcupines, a small area of scarring where a lateral branch/leader (LBL) had broken off in the past, and some past signs of Gall Rust disease. The DNR report concluded as follows: “It is my opinion that because of the unusual configuration of the tree, and its proximity to the powerline, a closer inspection was warranted. A nearer inspection of the tree should have revealed the cut LBL ends and its previous failure, and necessitated determination of the failure potential of the adjacent LBL, implicated in starting the Babb Road Fire.” The DNR report acknowledged that, other than the multi-dominant nature of the tree, the conditions mentioned above would not have been easily visible without close-up inspection of, or cutting into, the tree. The report also acknowledged that, while the presence of multiple tops would have been visible from the nearby roadway, the tree did not fail at a v-fork due to the presence of multiple tops. The Company contends that applicable inspection standards did not require a closer inspection of the otherwise healthy tree, nor was the Company negligent with respect to its maintenance, inspection or vegetation management practices. Nine lawsuits seeking unspecified damages have been filed in connection with the Babb Road fire. These include six subrogation actions filed by insurance companies seeking recovery for amounts paid to insureds; two actions on behalf of individual plaintiffs; and a class action lawsuit. All proceedings have been consolidated for discovery and pre-trial proceedings, are pending in the Superior Court of Spokane County Washington, and variously assert causes of action for negligence, private nuisance, trespass and inverse condemnation (a theory of strict liability). On September 16, 2022, the Company filed a motion in the Superior Court of Spokane County, Washington, seeking dismissal of the Plaintiffs' inverse condemnation claims as a matter of law on the grounds that they are not legally cognizable under Washington law. On October 14, 2022, the Superior Court heard oral argument on that motion. The Court concluded the Company's motion involved mixed questions of law and fact, and, as a consequence, could not be granted at that stage of the proceedings; however, the Court indicated the Company could bring the issue before the Court again after discovery is completed. The Company will vigorously defend itself in the legal proceedings; however, at this time the Company is unable to predict the likelihood of an adverse outcome or estimate a range of potential loss in the event of such an outcome. Colstrip Colstrip Owners Arbitration and Litigation Colstrip Units 3 and 4 are owned by the Company, PacifiCorp, Portland General Electric (PGE), and Puget Sound Energy (PSE) (collectively, the “Western Co-Owners”), as well as NorthWestern and Talen Montana, LLC (Talen), as tenants in common under an Ownership and Operating Agreement, dated May 6, 1981, as amended (O&O Agreement), in the percentages set forth below: Co-Owner Unit 3 Unit 4 Avista 15 % 15 % PacifiCorp 10 % 10 % PGE 20 % 20 % PSE 25 % 25 % NorthWestern — 30 % Talen 30 % — Colstrip Units 1 and 2, owned by PSE and Talen, were shut down in 2020 and are in the process of being decommissioned. The co-owners of Units 3 and 4 also own undivided interests in facilities common to both Units 3 and 4, as well as in certain facilities common to all four Colstrip units. The Washington Clean Energy Transformation Act (CETA), among other things, imposes deadlines by which each electric utility must eliminate from its electricity rates in Washington the costs and benefits associated with coal-fired resources, such as Colstrip. The practical impact of CETA is that electricity from such resources, including Colstrip, may no longer be delivered to Washington retail customers after 2025. The co-owners of Colstrip Units 3 and 4 have differing needs for the generating capacity of these units. Accordingly, certain business disagreements have arisen among the co-owners, including, disagreements as to the requirements for shutting down these units. NorthWestern has initiated arbitration pursuant to the O&O Agreement to resolve these business disagreements, and two actions have been initiated to compel arbitration of those disputes: one by Talen in the Montana Thirteenth Judicial District Court for Yellowstone County, and one by the Western Co-Owners, which is pending in Montana Federal District Court. In light of the ownership agreements discussed below, the Colstrip owners agreed to stay both the litigation and the arbitration until March 2023, at which time the proceedings would resume absent additional agreement between the owners. In addition, the Western Co-Owners commenced legal proceedings in the Montana Federal District Court challenging the constitutionality of two changes to Montana law enacted in 2021. The first, Senate Bill 265, purported to modify the provisions in the O&O Agreement governing arbitration of disputes; and the second, Senate Bill 266, made it a violation of Montana’s Consumer Protection Act (MC 30-14-103 et seq.) for an owner of Colstrip to either fail to fund its share of operating costs, or to attempt to bring about a closure of one or both units without unanimous consent. In September 2022, a Magistrate Judge issued proposed Findings and an Order finding that both Senate Bill 265 and 266 were unconstitutional and, in October 2022, the District Court Judge adopted the Magistrate’s findings and recommendations in full. Agreement Between Talen Energy and Puget Sound Energy In September 2022, the Company received notice that PSE and Talen entered into an agreement through which PSE has agreed to transfer its 25 percent ownership in Colstrip Units 3 and 4 to Talen at the end of 2025. The terms and conditions of the agreement are similar in most respects to the NorthWestern Transaction discussed below. Agreement Between Avista and NorthWestern On January 16, 2023, the Company entered into an agreement with NorthWestern under which the Company will transfer its 15 percent ownership in Colstrip Units 3 and 4 to NorthWestern. There is no monetary exchange included in the transaction. The transaction is scheduled to close on December 31, 2025 or such other date as the parties mutually agree upon. Under the agreement, the Company will remain obligated through the close of the transaction to pay its share of (i) operating expenses, (ii) capital expenditures, but not in excess of the portion allocable pro rata to the portion of useful life expired through the close of the transaction, and (iii) except for certain costs relating to post-closing activities, site remediation expenses. In addition, the Company would enter into a vote sharing agreement under which it would retain its voting rights with respect to decisions relating to remediation. The Company will retain its Colstrip transmission system assets, which are excluded from the transaction. Under the Colstrip O&O Agreement, each of the other owners of Colstrip will have a 90-day period in which to evaluate the transaction and determine whether to exercise their respective rights of first refusal as to a portion of the generation being turned over to NorthWestern. The transaction is subject to the satisfaction of customary closing conditions including the receipt of any required regulatory approvals, as well as NorthWestern's ability to enter into a new coal supply agreement by December 31, 2024. The Company does not expect this transaction to have a material impact on its financial results. Burnett et al. v. Talen et al. Multiple property owners have initiated a legal proceeding (titled Burnett et al. v. Talen et al.) in the Montana District Court for Rosebud County against Talen, PSE, Pacificorp, PGE, Avista Corp., NorthWestern, and Westmoreland Rosebud Mining. The plaintiffs allege a failure to contain coal dust in connection with the operation of Colstrip, and seek unspecified damages. The parties agreed to temporarily stay the litigation as a result of the bankruptcy proceedings initiated by Talen, which agreement was not impacted by the stipulation to lift the stay for purposes of the Montana litigation and arbitration. The Company will vigorously defend itself in the litigation, but at this time is unable to predict the outcome, nor an amount or range of potential impact in the event of an outcome that is adverse to the Company’s interests. Westmoreland Mine Permits Two lawsuits have been commenced by the Montana Environmental Information Center, challenging certain permits relating to the operation of the Westmoreland Rosebud Mine, which provides coal to Colstrip. In the first, the Montana District Court for Rosebud County issued an order vacating a permit for one area of the mine. In the second, the Montana Federal District Court issued findings and recommended that a decision approving expansion of the mine into a new area should be vacated, but recommending that the decision not take effect for 365 days from the date of a final order. Both decisions may be subject to appellate review. Avista Corp. is not a party to either of these proceedings, but is continuing to monitor the progress of both lawsuits and assess the impact, if any, of the proceedings on Westmoreland’s ability to meet its contractual coal supply obligations. National Park Service (NPS) - Natural and Cultural Damage Claim In March 2017, the Company accessed property managed by the National Park Service (NPS) to prevent the imminent failure of a power pole that was surrounded by flood water in the Spokane River. The Company voluntarily reported its actions to the NPS several days later. Thereafter, in March 2018, the NPS notified the Company that it might seek recovery for unspecified costs and damages allegedly caused during the incident pursuant to the System Unit Resource Protection Act (SURPA), 54 U.S.C. 100721 et seq. In January 2021, the United States Department of Justice (DOJ) requested that the Company and the DOJ renew discussions relating to the matter. In July 2021, the DOJ communicated that it may seek damages of approximately $ 2 million in connection with the incident for alleged damage to “natural and cultural resources”. In addition, the DOJ indicated that it may seek treble damages under the SURPA and state law, bringing its total potential claim to approximately $ 6 million. The Company disputes the position taken by the DOJ with respect to the incident, as well as the nature and extent of the DOJ’s alleged damages, and will vigorously defend itself in any litigation that may arise with respect to the matter. The Company and the DOJ have agreed to engage in discussions to understand their respective positions and determine whether a resolution of the dispute may be possible. However, the Company cannot predict the outcome of the matter. Rathdrum, Idaho Natural Gas Incident In October 2021, there was an incident in Rathdrum, Idaho involving the Company’s natural gas infrastructure. The incident occurred after a third party damaged those facilities during the course of excavation work. The incident resulted in a fire which destroyed one residence and resulted in minor injuries to the occupants. On January 23, 2023, the Company was served with a lawsuit filed in the District Court of Kootenai County, Idaho by one property owner, seeking unspecified damages. The Company intends to vigorously defend itself in this action. Other Contingencies In the normal course of business, the Company has various other legal claims and contingent matters outstanding. The Company believes that any ultimate liability arising from these actions will not have a material impact on its financial condition, results of operations or cash flows. It is possible that a change could occur in the Company’s estimates of the probability or amount of a liability being incurred. Such a change, should it occur, could be significant. The Company routinely assesses, based on studies, expert analysis and legal reviews, its contingencies, obligations and commitments for remediation of contaminated sites, including assessments of ranges and probabilities of recoveries from other responsible parties who either have or have not agreed to a settlement as well as recoveries from insurance carriers. The Company’s policy is to accrue and charge to current expense identified exposures related to environmental remediation sites based on estimates of investigation, cleanup and monitoring costs to be incurred. The Company has potential liabilities under the Endangered Species Act and similar state statutes for species of fish, plants and wildlife that have either already been added to the endangered species list, listed as “threatened” or petitioned for listing. Thus far, measures adopted and implemented have had minimal impact on the Company. However, the Company will continue to seek recovery, through the ratemaking process, of all operating and capitalized costs related to these issues. Under the federal licenses for its hydroelectric projects, the Company is obligated to protect its property rights, including water rights. In addition, the Company holds additional non-hydro water rights. The State of Montana is examining the status of all water right claims within state boundaries through a general adjudication. Claims within the Clark Fork River basin could adversely affect the energy production of the Company’s Cabinet Gorge and Noxon Rapids hydroelectric facilities. The state of Idaho has initiated adjudication in northern Idaho, which will ultimately include the lower Clark Fork River, the Spokane River and the Coeur d’Alene basin. The Company is and will continue to be a participant in these and any other relevant adjudication processes. The complexity of such adjudications makes each unlikely to be concluded in the foreseeable future. As such, it is not possible for the Company to estimate the impact of any outcome at this time. The Company will continue to seek recovery, through the ratemaking process, of all costs related to this issue.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2022
Regulated Operations [Abstract]
Regulatory Matters	NOTE 23. REGUL ATORY MATTERS Regulatory Assets and Liabilities The following table presents the Company’s regulatory assets and liabilities as of December 31, 2022 (dollars in thousands): Receiving 2022 2021 Remaining (1) Not (2) Current Non- Current Non- Regulatory Assets: Deferred income tax (3 ) $ 240,325 $ — $ — $ — $ 240,325 $ — $ 244,154 Pensions and other (4 ) — 135,337 — — 135,337 — 165,696 Energy commodity (5 ) — 130,275 — 112,090 18,185 12,447 2,938 Unamortized debt repurchase (6 ) 6,177 — — — 6,177 — 6,768 Settlement with 2059 37,809 — — — 37,809 — 38,926 Demand side management (3 ) — 3,683 — — 3,683 — 3,974 Decoupling surcharge 2025 11,699 — — 6,250 5,449 9,907 14,625 Utility plant abandoned (7 ) 24,389 — — — 24,389 — 26,771 Interest rate swaps (8 ) 168,832 — 17,087 — 185,919 — 199,754 Deferred power costs (3 ) 47,399 — — 23,356 24,043 7,334 3,501 Deferred natural gas costs (3 ) 52,091 — — 52,091 — 14,095 6,932 AFUDC above FERC (11 ) 51,649 — — — 51,649 — 48,455 COVID-19 deferrals (12 ) — 1,650 8,143 — 9,793 — 13,591 Advanced meter infrastructure (13 ) 32,381 — — — 32,381 — 36,008 Other regulatory assets (3 ) 40,163 14,871 3,155 — 58,189 — 48,533 Total regulatory assets $ 712,914 $ 285,816 $ 28,385 $ 193,787 $ 833,328 $ 43,783 $ 860,626 Regulatory Liabilities: Deferred power costs (3 ) $ — $ — $ — $ — $ — $ 6,457 $ 5,434 Utility plant retirement costs (9 ) 376,817 — — — 376,817 — 350,190 Income tax related liabilities (3) (10) 427,365 27,458 9,178 73,267 390,734 56,331 458,789 Interest rate swaps (8 ) 13,020 — 11,184 — 24,204 — 15,062 Decoupling rebate 2025 29,945 — — 9,469 20,476 3,049 6,259 COVID-19 deferrals (12 ) — 1,227 10,647 — 11,874 — 12,500 Other regulatory liabilities (3 ) 6,718 22,943 — 12,929 16,732 11,312 13,281 Total regulatory liabilities $ 853,865 $ 51,628 $ 31,009 $ 95,665 $ 840,837 $ 77,149 $ 861,515 (1) Earning a return includes either interest on the regulatory asset/liability or a return on the investment as a component of rate base at the allowed rate of return. (2) Expected recovery is pending regulatory treatment including regulatory assets and liabilities with prior regulatory precedence. (3) Remaining amortization period varies depending on timing of underlying transactions. (4) As the Company has historically recovered and currently recovers its pension and other postretirement benefit costs related to its regulated operations in retail rates, the Company records a regulatory asset for that portion of its pension and other postretirement benefit funding deficiency. (5) The WUTC and the IPUC issued accounting orders authorizing Avista Corp. to offset energy commodity derivative assets or liabilities with a regulatory asset or liability. This accounting treatment is intended to defer the recognition of mark-to-market gains and losses on energy commodity transactions until the period of delivery. Realized benefits and losses result in adjustments to retail rates through PGAs, the ERM in Washington, the PCA mechanism in Idaho and periodic general rates cases. The resulting regulatory assets associated with energy commodity derivative instruments have been concluded to be probable of recovery through future rates. (6) Premiums paid or discounts received to repurchase debt are amortized over the remaining life of the original debt that was repurchased or, if new debt is issued in connection with the repurchase, these costs are amortized over the life of the new debt. These costs are recovered through retail rates as a component of interest expense. (7) The WUTC approved recovery of AMI project costs through the 2020 general rate case settlements, including amortization of retired meters replaced through the project through 2033. There are additional smaller projects included in the balance that the Company expects to fully recover, which have not yet been through the regulatory process. (8) For interest rate swap derivatives, Avista Corp. records all mark-to-market gains and losses in each accounting period as assets and liabilities, as well as offsetting regulatory assets and liabilities, such that there is no income statement impact. The interest rate swap derivatives are risk management tools similar to energy commodity derivatives. Upon settlement of interest rate swap derivatives, the regulatory asset or liability is amortized as a component of interest expense over the term of the associated debt. The Company records an offset of interest rate swap derivative assets and liabilities with regulatory assets and liabilities, based on the prior practice of the commissions to provide recovery through the ratemaking process. Settled interest rate swap derivatives which have been through a general rate case proceeding are classified as earning a return in the table above, whereas all unsettled interest rate swap derivatives and settled interest rate swap derivatives which have not been included in a general rate case are classified as expected recovery. (9) This amount is dependent upon the cost of removal of underlying utility plant assets and the life of utility plant. (10) The majority of this balance represents amounts due back to customers and resulted from the Tax Cuts and Jobs Act signed into law in December 2017, which changed the federal income tax rate from 35 percent to 21 percent. The Company revalued all deferred income taxes as of December 31, 2017. The Company expects the amounts for utility plant items for Avista Utilities to be returned to customers over a period of approximately 33 years . The Company expects the AEL&P amounts to be returned to customers over a period of approximately 22 years. Prior to 2022, for depreciation-related temporary differences under the normalized tax accounting method, the Company utilized the average rate assumption method to compute the amounts returned to customers. Beginning in 2022, the Company changed to the alternative method, to be in compliance with recently released revenue procedures and private letter rulings. (11) This amount is being amortized based on the underlying utility plant assets and the life of utility plant. (12) The WUTC, IPUC and OPUC issued accounting orders allowing the Company to defer certain costs, net of any benefits, related to the COVID-19 pandemic. The Company has recorded all benefits on a gross basis as a regulatory liability to customers and all additional allowed costs are a regulatory asset. The ratemaking treatment will be determined in future general rate cases in each jurisdiction. (13) This amount represents the deferral of the depreciation expense of the Company’s AMI project in Washington state. Recovery of these amounts was approved by WUTC in the 2021 general rate case order, and the asset will be amortized through 2033. Power Cost Deferrals and Recovery Mechanisms Deferred power supply costs are recorded as a deferred charge or liability on the Consolidated Balance Sheets for future prudence review and recovery or rebate through retail rates. The power supply costs deferred include certain differences between actual net power supply costs incurred by Avista Utilities and the costs included in base retail rates. This difference in net power supply costs primarily results from changes in: • short-term wholesale market prices and sales and purchase volumes, • the level, availability and optimization of hydroelectric generation, • the level and availability of thermal generation (including changes in fuel prices), • retail loads, and • sales of surplus transmission capacity. In Washington, the ERM allows Avista Utilities to periodically increase or decrease electric rates with WUTC approval to reflect changes in power supply costs. The ERM is an accounting method used to track certain differences between actual power supply costs, net of wholesale sales and sales of fuel, and the amount included in base retail rates for Washington customers and defer these differences (over the $ 4.0 million deadband and sharing bands) for future surcharge or rebate to customers. For 2022, the Company recognized a pre-tax expense of $ 10.9 million under the ERM in Washington compared to a pre-tax expense of $ 7.7 million for 2021. Total net deferred power costs under the ERM were an asset of $ 30.5 million as of December 31, 2022 and a liability of $ 11.9 million as of December 31, 2021. The deferred power cost asset balance at December 31, 2022 represents amounts due from customers. Pursuant to WUTC requirements, should the cumulative deferral balance exceed $ 30 million in the rebate or surcharge direction, the Company must make a filing with the WUTC to adjust customer rates to either return the balance to customers or recover the balance from customers. Avista Utilities makes an annual filing on, or before, April 1 of each year to provide the opportunity for the WUTC staff and other interested parties to review the prudence of, and audit, the ERM deferred power cost transactions for the prior calendar year. The cumulative surcharge balance as of December 31, 2022 exceeded $ 30 million and as a result, the Company expects the April 2023 filing to contain a proposed rate surcharge to be received from customers over a one-year period, with new rates effective July 1, 2023. Avista Utilities has a PCA mechanism in Idaho that allows it to modify electric rates on October 1 of each year with IPUC approval. Under the PCA mechanism, Avista Utilities defers 90 percent of the difference between certain actual net power supply expenses and the amount included in base retail rates for its Idaho customers. The October 1 rate adjustments recover or rebate power costs deferred during the preceding July-June twelve-month period. Total net power supply costs deferred under the PCA mechanism were an asset o f $ 16.3 million a s of December 31, 2022 and $ 10.8 million as of December 31, 2021. Deferred power cost assets represent amounts due from customers and liabilities represent amounts due to customers. Natural Gas Cost Deferrals and Recovery Mechanisms Avista Utilities files a PGA in all three states it serves to adjust natural gas rates for: 1) estimated commodity and pipeline transportation costs to serve natural gas customers for the coming year, and 2) the difference between actual and estimated commodity and transportation costs for the prior year. Total net deferred natural gas costs were an asset of $ 52.1 million as of December 31, 2022 and $ 21.0 million as of December 31, 2021. Asset balances represent amounts due from customers and liabilities represent amounts due to customers. Decoupling and Earnings Sharing Mechanisms Decoupling (also known as an FCA in Idaho) is a mechanism designed to sever the link between a utility's revenues and consumers' energy usage. In each of Avista Utilities' jurisdictions, Avista Utilities' electric and natural gas revenues are adjusted so as to be based on the number of customers in certain customer rate classes and assumed “normal” kilowatt hour and therm sales, rather than being based on actual kilowatt hour and therm sales. The difference between revenues based on the number of customers and “normal” sales and revenues based on actual usage is deferred and either surcharged or rebated to customers beginning in the following year. Only residential and certain commercial customer classes are included in decoupling mechanisms. Washington Decoupling and Earnings Sharing In Washington, the WUTC approved the Company's decoupling mechanisms for electric and natural gas for a five-year period beginning January 1, 2015. In 2019, the WUTC approved an extension of the mechanisms for an additional five-year term through March 31, 2025, with one modification in that new customers added after any test period would not be decoupled until included in a future test period. Electric and natural gas decoupling surcharge rate adjustments to customers are limited to a 3 percent increase on an annual basis, with any remaining surcharge balance carried forward for recovery in a future period. There is no limit on the level of rebate rate adjustments. The decoupling mechanisms each include an after-the-fact earnings test. At the end of each calendar year, separate electric and natural gas earnings calculations are made for the calendar year just ended. These earnings tests reflect actual decoupled revenues, normalized power supply costs and other normalizing adjustments. Through the 2022 general rate cases, the Company modified its earnings test so that if the Company earns more than 0.5 percent higher than the ROR authorized by the WUTC in the multi-year rate plan, the Company would defer these excess revenues and later return them to customers. Idaho FCA and Earnings Sharing Mechanisms In Idaho, the IPUC approved the implementation of FCAs for electric and natural gas through March 31, 2025. Oregon Decoupling Mechanism In Oregon, the Company has a decoupling mechanism for natural gas. An earnings review is conducted on an annual basis. In the annual earnings review, if the Company earns more than 100 basis points above its allowed ROE, one-third of the earnings above the 100 basis points would be deferred and later returned to customers. The earnings review is separate from the decoupling mechanism and was in place prior to decoupling. Cumulative Decoupling and Earnings Sharing Mechanism Balances As of December 31, 2022 and December 31, 2021, the Company had the following cumulative balances outstanding related to decoupling and earnings sharing mechanisms in its various jurisdictions (dollars in thousands): December 31, December 31, 2022 2021 Washington Decoupling (rebate) surcharge $ ( 13,210 ) $ 13,522 Idaho Decoupling rebate $ ( 7,889 ) $ ( 1,450 ) Provision for earnings sharing rebate ( 686 ) ( 686 ) Oregon Decoupling surcharge $ 2,853 $ 3,152 There were no earnings sharing rebates associated with Washington and Oregon as of December 31, 2022 and December 31, 2021. 2022 Washington General Rate Cases In June 2022, the Company and certain other parties entered into a Settlement Agreement that resolved all issues in the Company's electric and natural gas general rate cases originally filed in January 2022. The Public Counsel Unit of the Washington Attorney General’s Office (Public Counsel), while a party to the rate cases, did not join in the Settlement Agreement. The Settlement Agreement was reached after negotiation of all issues but is “results-focused” -- that is, it represents agreement among all parties (except Public Counsel) as to the Company’s overall revenue requirement, without specifying the details of any component except the rate of return on rate base. On December 12, 2022, the WUTC issued an order approving the multi-party Settlement Agreement. On December 22, 2022, Public Counsel filed a Petition for Reconsideration requesting the WUTC to reconsider its ruling on the Settlement Agreement. Public Counsel’s primary issue is related to the “results-focused” approach used by the settling parties and approved by the WUTC. On January 30, 2023, the WUTC issued an order denying the Petition for Reconsideration, stating that Public Counsel was afforded every opportunity to exercise its rights to oppose the settlement, and reiterated that the end results of the settlement produced rates that were equitable, fair, just, reasonable and sufficient.

Information by Business Segment

Information by Business Segments	12 Months Ended
	Dec. 31, 2022
Segment Reporting [Abstract]
Information by Business Segments	NOTE 24. INFORMATION BY BUSINESS SEGMENTS The business segment presentation reflects the basis used by the Company's management to analyze performance and determine the allocation of resources. The Company's management evaluates performance based on income (loss) from operations before income taxes as well as net income (loss). The accounting policies of the segments are the same as those described in the summary of significant accounting policies. Avista Utilities' business is managed based on the total regulated utility operation; therefore, it is considered one segment. AEL&P is a separate reportable business segment as it has separate financial reports that are reviewed in detail by the Chief Operating Decision Maker and its operations and risks are sufficiently different from Avista Utilities and the other businesses at AERC that it cannot be aggregated with any other operating segments. The Other category, which is not a reportable segment, includes other investments and operations of various subsidiaries, as well as certain other operations of Avista Capital. The following table presents information for each of the Company’s business segments (dollars in thousands): Avista Alaska Total Utility Other Intersegment Total For the year ended Operating revenues $ 1,663,815 $ 45,704 $ 1,709,519 $ 688 $ — $ 1,710,207 Resource costs 732,298 3,564 735,862 — — 735,862 Other operating expenses 390,597 14,568 405,165 11,603 — 416,768 Depreciation and amortization 242,198 10,819 253,017 125 — 253,142 Income (loss) from operations 185,582 15,700 201,282 ( 11,040 ) — 190,242 Interest expense (2) 112,213 5,960 118,173 791 ( 272 ) 118,692 Income taxes ( 27,368 ) 2,337 ( 25,031 ) 7,840 — ( 17,191 ) Net income 117,901 7,545 125,446 29,730 — 155,176 Capital expenditures (3) 443,373 8,622 451,995 834 — 452,829 For the year ended Operating revenues $ 1,392,999 $ 45,366 $ 1,438,365 $ 571 $ — $ 1,438,936 Resource costs 493,289 3,834 497,123 — — 497,123 Other operating expenses 352,241 13,884 366,125 5,927 — 372,052 Depreciation and amortization 221,552 10,363 231,915 261 — 232,176 Income (loss) from operations 217,663 16,186 233,849 ( 5,617 ) — 228,232 Interest expense (2) 99,629 6,096 105,725 522 ( 95 ) 106,152 Income taxes 6,029 2,763 8,792 3,239 — 12,031 Net income 125,558 7,224 132,782 14,552 — 147,334 Capital expenditures (3) 435,887 4,052 439,939 1,270 — 441,209 For the year ended Operating revenues $ 1,277,468 $ 42,809 $ 1,320,277 $ 1,614 $ — $ 1,321,891 Resource costs 396,543 1,966 398,509 — — 398,509 Other operating expenses 341,709 12,905 354,614 5,344 — 359,958 Depreciation and amortization 213,701 9,806 223,507 716 — 224,223 Income (loss) from operations 220,058 17,088 237,146 ( 4,446 ) — 232,700 Interest expense (2) 98,451 6,272 104,723 524 ( 186 ) 105,061 Income taxes 4,921 3,011 7,932 ( 881 ) — 7,051 Net income (loss) 124,810 8,095 132,905 ( 3,417 ) — 129,488 Capital expenditures (3) 397,292 7,014 404,306 1,368 — 405,674 Total Assets: As of December 31, 2022 $ 6,976,164 $ 264,322 $ 7,240,486 $ 187,027 $ ( 10,163 ) $ 7,417,350 As of December 31, 2021 6,458,244 265,422 6,723,666 132,158 ( 2,241 ) 6,853,583 As of December 31, 2020 6,035,340 268,971 6,304,311 109,658 ( 11,872 ) 6,402,097 (1) Intersegment eliminations reported as interest expense represent intercompany interest. Intersegment eliminations reported as assets represent intersegment accounts receivable. (2) Including interest expense to affiliated trusts. (3) The capital expenditures for the other businesses are included in other investing activities on the Consolidated Statements of Cash Flows.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Nature of Business	Nature of Business Avista Corp. is primarily an electric and natural gas utility with certain other business ventures. Avista Utilities is an operating division of Avista Corp., comprising its regulated utility operations in the Pacific Northwest. Avista Utilities provides electric distribution and transmission, and natural gas distribution services in parts of eastern Washington and northern Idaho. Avista Utilities also provides natural gas distribution service in parts of northeastern and southwestern Oregon. Avista Utilities has electric generating facilities in Washington, Idaho, Oregon and Montana. Avista Utilities also supplies electricity to a small number of customers in Montana, most of whom are employees who operate the Company's Noxon Rapids generating facility. AERC is a wholly-owned subsidiary of Avista Corp. The primary subsidiary of AERC is AEL&P, which comprises Avista Corp.'s regulated utility operations in Alaska. Avista Capital, a wholly owned non-regulated subsidiary of Avista Corp., is the parent company of all of the subsidiary companies in the non-utility businesses, with the exception of AJT Mining Properties, Inc., which is a subsidiary of AERC. See Note 24 for business segment information.
Basis of Reporting	Basis of Reporting The consolidated financial statements include the assets, liabilities, revenues and expenses of the Company and its subsidiaries and other majority owned subsidiaries and variable interest entities for which the Company or its subsidiaries are the primary beneficiaries. Intercompany balances were eliminated in consolidation. The accompanying consolidated financial statements include the Company’s proportionate share of utility plant and related operations resulting from its interests in jointly owned plants (see Note 9 ).
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported for assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates include: • determining the market value of energy commodity derivative assets and liabilities, • pension and other postretirement benefit plan obligations, • contingent liabilities, • goodwill impairment testing, • fair value of equity investments, • recoverability of regulatory assets, and • unbilled revenues. Changes in these estimates and assumptions are considered reasonably possible and may have a material effect on the consolidated financial statements and thus actual results could differ from the amounts reported and disclosed herein.
Regulation	Regulation The Company is subject to state regulation in Washington, Idaho, Montana, Oregon and Alaska. The Company is also subject to federal regulation primarily by the FERC, as well as various other federal agencies with regulatory oversight of particular aspects of its operations. Regulatory Deferred Charges and Credits The Company prepares its consolidated financial statements in accordance with regulatory accounting practices because: • rates for regulated services are established by or subject to approval by independent third-party regulators, • the regulated rates are designed to recover the cost of providing the regulated services, and • in view of demand for the regulated services and the level of competition, it is reasonable to assume that rates can be charged to and collected from customers at levels that will recover costs. Regulatory accounting practices require that certain costs and/or obligations (such as incurred power and natural gas costs not currently reflected in rates, but expected to be recovered or refunded in the future), are reflected as deferred charges or credits on the Consolidated Balance Sheets. These costs and/or obligations are not reflected in the Consolidated Statements of Income until the period during which matching revenues are recognized. The Company also has decoupling revenue deferrals. See Note 4 for discussion on decoupling revenue deferrals. If at some point in the future the Company determines that it no longer meets the criteria for continued application of regulatory accounting practices for all or a portion of its regulated operations, the Company could be: • required to write off its regulatory assets, and • precluded from the future deferral of costs or decoupled revenues not recovered through rates at the time such amounts are incurred, even if the Company expected to recover these amounts from customers in the future. See Note 23 for further details of regulatory assets and liabilities.
Depreciation	Depreciation For utility operations, depreciation expense is estimated by a method of depreciation accounting utilizing composite rates for utility plant. Such rates are designed to provide for retirements of properties at the expiration of their service lives. For utility operations, the ratio of depreciation provisions to average depreciable property was as follows for the years ended December 31: 2022 2021 2020 Avista Utilities Ratio of depreciation to average depreciable property 3.50 % 3.54 % 3.43 % Alaska Electric Light and Power Company Ratio of depreciation to average depreciable property 2.78 % 2.77 % 2.77 % The average service lives for the following broad categories of utility plant in service are (in years): Avista Utilities Alaska Electric Light Electric thermal/other production 26 41 Hydroelectric production 79 42 Electric transmission 50 43 Electric distribution 39 39 Natural gas distribution property 44 N/A Other shorter-lived general plant 8 19
Allowance for Funds Used During Construction	Allowance for Funds Used During Construction AFUDC represents the cost of both the debt and equity funds used to finance utility plant additions during the construction period. As prescribed by regulatory authorities, AFUDC is capitalized as a part of the cost of utility plant. The debt component of AFUDC is credited against total interest expense in the Consolidated Statements of Income in the line item “capitalized interest.” The equity component of AFUDC is included in the Consolidated Statements of Income in the line item “other income-net.” The Company is permitted, under established regulatory rate practices, to recover the capitalized AFUDC, and a reasonable return thereon, through its inclusion in rate base and the provision for depreciation after the related utility plant is placed in service. Cash inflow related to AFUDC does not occur until the related utility plant is placed in service and included in rate base. The WUTC and IPUC have authorized Avista Utilities to calculate AFUDC using its allowed rate of return. To the extent amounts calculated using this rate exceed the AFUDC amounts calculated using the FERC formula, Avista Utilities capitalizes the excess as a regulatory asset. The regulatory asset associated with plant in service is amortized over the average useful life of Avista Utilities' utility plant which is approximately 30 years. The regulatory asset associated with construction work in progress is not amortized until the plant is placed in service. The effective AFUDC rate was the following for the years ended December 31: 2022 2021 2020 Avista Utilities 7.12 % 7.19 % 7.25 % Alaska Electric Light and Power Company 8.08 % 8.90 % 8.04 %
Income Taxes	Income Taxes Deferred income tax assets represent future income tax deductions the Company expects to utilize in future tax returns to reduce taxable income. Deferred income tax liabilities represent future taxable income the Company expects to recognize in future tax returns. Deferred tax assets and liabilities arise when there are temporary differences resulting from differing treatment of items for tax and accounting purposes. A deferred income tax asset or liability is determined based on the enacted tax rates that will be in effect when the temporary differences between the financial statement carrying amounts and tax basis of existing assets and liabilities are expected to be reported in the Company’s consolidated income tax returns. The effect on deferred income taxes from a change in tax rates is recognized in income in the period that includes the enactment date unless a regulatory order specifies deferral of the effect of the change in tax rates over a longer period of time. The Company establishes a valuation allowance when it is more likely than not that all, or a portion, of a deferred tax asset will not be realized. Deferred income tax assets and liabilities and regulatory assets and liabilities are established for income tax benefits flowed through to customers. The Company's largest deferred income tax item is the difference between the book and tax basis of utility plant. This item results from the temporary difference on depreciation expense. In early tax years, this item is recorded as a deferred income tax liability that will eventually reverse and become subject to income tax in later tax years. The Company did no t incur any penalties on income tax positions in 2022, 2021 or 2020 . The Company would recognize interest accrued related to income tax positions as interest expense and any penalties incurred as other operating expense.
Stock-Based Compensation	Stock-Based Compensation The Company currently issues three types of stock-based compensation awards - restricted shares, market-based awards and performance-based awards. Historically, these stock compensation awards have not been material to the Company's overall financial results. Compensation cost relating to share-based payment transactions is recognized in the Company’s financial statements based on the fair value of the equity instruments issued and recorded over the requisite service period. The Company recorded stock-based compensation expense (included in other operating expenses) and income tax benefits in the Consolidated Statements of Income of the following amounts for the years ended December 31 (dollars in thousands): 2022 2021 2020 Stock-based compensation expense $ 7,567 $ 4,713 $ 5,846 Income tax benefits 1,589 990 1,228 Excess tax expenses on settled share-based employee ( 19 ) ( 909 ) ( 165 ) Restricted share awards vest in equal thirds each year over 3 years and are payable in Avista Corp. common stock at the end of each year if the service condition is met. Restricted stock is valued at the close of market of the Company’s common stock on the grant date. Total Shareholder Return (TSR) awards are market-based awards and Cumulative Earnings Per Share (CEPS) awards are performance awards. Both types of awards vest after a period of 3 years and are payable in cash or Avista Corp. common stock at the end of the three-year period. The method of settlement is at the discretion of the Company and historically the Company has settled these awards through issuance of Avista Corp. common stock and intends to continue this practice. Both types of awards entitle the recipients to dividend equivalent rights, are subject to forfeiture under certain circumstances, and are subject to meeting specific market or performance conditions. Based on the level of attainment of the market or performance conditions, the amount of cash paid or common stock issued will range from 0 to 200 percent of the initial awards granted. Dividend equivalent rights are accumulated and paid out only on shares that eventually vest and have met the market and performance conditions. The Company accounts for both the TSR awards and CEPS awards as equity awards and compensation cost for these awards is recognized over the requisite service period, provided that the requisite service period is rendered. For TSR awards, if the market condition is not met at the end of the three-year service period, there will be no change in the cumulative amount of compensation cost recognized, since the awards are still considered vested even though the market metric was not met. For CEPS awards, at the end of the three-year service period, if the internal performance metric of cumulative earnings per share is not met, all compensation cost for these awards is reversed as these awards are not considered vested. The fair value of each TSR award is estimated on the date of grant using a statistical model that incorporates the probability of meeting the market targets based on historical returns relative to a peer group. The estimated fair value of the CEPS awards was estimated on the date of grant as the share price of Avista Corp. common stock on the date of grant. The following table summarizes the number of grants, vested and unvested shares, earned shares (based on market metrics), and other pertinent information related to the Company's stock compensation awards for the years ended December 31: 2022 2021 2020 Restricted Shares Shares granted during the year 115,746 62,594 45,540 Shares vested during the year 44,829 34,854 56,203 Unvested shares at end of year 157,860 96,127 71,706 Unrecognized compensation expense at end of year $ 3,923 $ 2,215 $ 2,003 TSR Awards TSR shares granted during the year 69,814 64,910 47,848 TSR shares vested during the year 43,730 77,174 71,299 TSR shares earned based on market metrics 48,890 58,652 — Unvested TSR shares at end of year 130,567 107,854 122,133 Unrecognized compensation expense at end of year $ 3,533 $ 2,653 $ 2,296 CEPS Awards CEPS shares granted during the year 69,814 64,910 47,848 CEPS shares vested during the year 43,730 38,590 35,622 CEPS shares earned based on market metrics — 26,627 63,763 Unvested CEPS shares at end of year 130,567 107,854 83,464 Unrecognized compensation expense at end of year $ 2,471 $ 1,223 $ 1,090 Outstanding restricted, TSR and CEPS share awards include a dividend component that is paid in cash. A liability for the dividends payable related to these awards is accrued as dividends are announced throughout the life of the award. As of December 31, 2022 and 2021, the Company had recognized a liabi lity of $ 1.7 million and $ 1.5 million, respectively, related to the dividend equivalents payable on the outstanding and unvested share grants.
Other Expense (Income) - Net	Other Income - Net Other income - net consisted of the following items for the years ended December 31 (dollars in thousands): 2022 2021 2020 Interest income $ ( 1,957 ) $ ( 1,943 ) $ ( 1,952 ) Interest on regulatory deferrals ( 1,914 ) ( 1,206 ) ( 1,222 ) Equity-related AFUDC ( 6,704 ) ( 7,004 ) ( 6,970 ) Non-service portion of pension and other postretirement benefit ( 3,037 ) 1,386 6,433 Earnings on investments ( 48,492 ) ( 21,402 ) ( 905 ) Other income ( 613 ) ( 3,129 ) ( 201 ) Total $ ( 62,717 ) $ ( 33,298 ) $ ( 4,817 )
Earnings per Common Share	Earnings per Common Share Basic earnings per common share is computed by dividing net income by the weighted-average number of common shares outstanding for the period. Diluted earnings per common share is calculated by dividing net income by diluted weighted-average common shares outstanding during the period, including common stock equivalent shares outstanding using the treasury stock method, unless such shares are anti-dilutive. Common stock equivalent shares include shares issuable under contingent stock awards. See Note 21 for earnings per common share calculations.
Cash and Cash Equivalents	Cash and Cash Equivalents For the purposes of the Consolidated Statements of Cash Flows, the Company considers all temporary investments with a maturity of three months or less when purchased to be cash equivalents.
Allowance For Doubtful Accounts	Allowance for Doubtful Accounts The Company maintains an allowance for doubtful accounts to provide for estimated and potential losses on accounts receivable. The Company determines the allowance for utility and other customer accounts receivable based on historical write-offs as compared to accounts receivable and operating revenues. Additionally, the Company establishes specific allowances for certain individual accounts. The following table presents the activity in the allowance for doubtful accounts during the years ended December 31 (dollars in thousands): 2022 2021 2020 Allowance as of the beginning of the year $ 10,465 $ 11,387 $ 2,419 Additions expensed during the year (1) 149 9,279 11,280 Net deductions (2) ( 4,141 ) ( 10,201 ) ( 2,312 ) Allowance as of the end of the year $ 6,473 $ 10,465 $ 11,387 (1) Increases in 2021 and 2020 related to COVID-19 bad debt expense in excess of the amount recovered through rates. (2) Increase in 2021 relates to COVID forgiveness program. The Company also received support from various government agencies in 2022 in the amount of $ 6.1 million, which was applied to overdue customer accounts.
Utility Plant in Service	Utility Plant in Service The cost of additions to utility plant in service, including an allowance for funds used during construction and replacements of units of property and improvements, is capitalized. The cost of depreciable units of property retired plus the cost of removal less salvage is charged to accumulated depreciation.
Asset Retirement Obligations	Asset Retirement Obligations The Company records the fair value of a liability for an ARO in the period in which it is incurred. When the liability is initially recorded, the associated costs of the ARO are capitalized as part of the carrying amount of the related long-lived asset. The liability is accreted to its present value each period and the related capitalized costs are depreciated over the useful life of the related asset. In addition, if there are changes in the estimated timing or estimated costs of the AROs, adjustments are recorded during the period new information becomes available as an increase or decrease to the liability, with the offset recorded to the related long-lived asset. Upon retirement of the asset, the Company either settles the ARO for its recorded amount or recognizes a regulatory asset or liability for the difference, which will be surcharged/refunded to customers through the ratemaking process. The Company records regulatory assets and liabilities for the difference between asset retirement costs currently recovered in rates and AROs recorded since asset retirement costs are recovered through rates charged to customers (see Note 11 for further discussion of the Company's AROs). The Company recovers certain asset retirement costs through rates charged to customers as a portion of its depreciation expense for which the Company has not recorded asset retirement obligations. The Company has recorded the amount of estimated retirement costs collected from customers (that do not represent legal or contractual obligations) and included them as a non-current regulatory liability on the Consolidated Balance Sheets in the following amounts as of December 31 (dollars in thousands): 2022 2021 Regulatory liability for utility plant retirement costs $ 376,817 $ 350,190
Goodwill	Goodwill Goodwill arising from acquisitions represents the future economic benefit arising from other assets acquired in a business combination that are not individually identified and separately recognized. The Company evaluates goodwill for impairment using a fair value to carrying amount comparison (Step 1). The Company completed its annual evaluation of goodwill for potential impairment as of November 30, 2022 and determined that goodwill was not impaired at that time (carrying value was less than the determined fair value). There were no events or circumstances that changed between November 30, 2022 and December 31, 2022 that would more likely than not reduce the fair values of the reporting units below their carrying amounts. There were no changes in the carrying amount of goodwill during 2021 and 2022 and the balance was as follows (dollars in thousands): AEL&P Accumulated Impairment Losses Total Balance as of December 31, 2021 and 2022 $ 52,426 $ - $ 52,426
Derivative Assets and Liabilities	Derivative Assets and Liabilities Derivatives are recorded as either assets or liabilities on the Consolidated Balance Sheets measured at estimated fair value. The WUTC and the IPUC issued accounting orders authorizing Avista Corp. to offset energy commodity derivative assets or liabilities with a regulatory asset or liability. This accounting treatment is intended to defer the recognition of mark-to-market gains and losses on energy commodity transactions until the period of delivery. Realized benefits and costs result in adjustments to retail rates through PGAs, the ERM in Washington, the PCA mechanism in Idaho, and periodic general rates cases. The resulting regulatory assets associated with energy commodity derivative instruments have been concluded to be probable of recovery through future rates. Substantially all forward contracts to purchase or sell power and natural gas are recorded as derivative assets or liabilities at estimated fair value with an offsetting regulatory asset or liability. Contracts that are not considered derivatives are accounted for on the accrual basis until they are settled or realized unless there is a decline in the fair value of the contract that is determined to be other-than-temporary. For interest rate swap derivatives, Avista Corp. records all mark-to-market gains and losses in each accounting period as assets and liabilities, as well as offsetting regulatory assets and liabilities, such that there is no income statement impact. The interest rate swap derivatives are risk management tools similar to energy commodity derivatives. Upon settlement of interest rate swap derivatives, the regulatory asset or liability is amortized as a component of interest expense over the term of the associated debt. The Company records an offset of interest rate swap derivative assets and liabilities with regulatory assets and liabilities, based on the prior practice of the commissions to provide recovery through the ratemaking process. The Company has multiple master netting agreements with a variety of entities that allow for cross-commodity netting of derivative agreements with the same counterparty (i.e. power derivatives can be netted with natural gas derivatives). In addition, some master netting agreements allow for the netting of commodity derivatives and interest rate swap derivatives for the same counterparty. The Company does not have any agreements which allow for cross-affiliate netting among multiple affiliated legal entities. The Company nets all derivative instruments when allowed by the agreement for presentation in the Consolidated Balance Sheets.
Fair Value Measurements	Fair Value Measurements Fair value represents the price that would be received when selling an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. Energy commodity derivative assets and liabilities, deferred compensation assets, some equity investments, as well as derivatives related to interest rate swap derivatives and foreign currency exchange derivatives, are reported at estimated fair value on the Consolidated Balance Sheets. See Note 18 for the Company’s fair value disclosures.
Unamortized Debt Expense	Unamortized Debt Expense Unamortized debt expense includes debt issuance costs that are amortized over the life of the related debt. These costs are recorded as an offset to Long-Term Debt on the Consolidated Balance Sheets. Unamortized Debt Repurchase Costs Premiums paid or discounts received to repurchase debt are amortized over the remaining life of the original debt that was repurchased or, if new debt is issued in connection with the repurchase, these costs are amortized over the life of the new debt. These costs are recovered through retail rates as a component of interest expense.
Appropriated Retained Earnings	Appropriated Retained Earnings In accordance with the hydroelectric licensing requirements of section 10(d) of the Federal Power Act (FPA), the Company maintains an appropriated retained earnings account for any earnings in excess of the specified rate of return on the Company's investment in the licenses for its various hydroelectric projects. Per section 10(d) of the FPA, the Company must maintain these excess earnings in an appropriated retained earnings account until the termination of the licensing agreements or apply them to reduce the net investment in the licenses of the hydroelectric projects at the discretion of the FERC. The Company calculates the earnings in excess of the specified rate of return on an annual basis, usually during the second quarter. The appropriated retained earnings amounts included in retained earnings were as follows as of December 31 (dollars in thousands): 2022 2021 Appropriated retained earnings $ 57,231 $ 53,620
Contingencies	Contingencies The Company has unresolved regulatory, legal and tax issues which have inherently uncertain outcomes. The Company accrues a loss contingency if it is probable that a liability has been incurred and the amount of the loss or impairment can be reasonably estimated. The Company also discloses loss contingencies that do not meet these conditions for accrual, if there is a reasonable possibility that a material loss may be incurred. As of December 31, 2022, the Company has not recorded any significant amounts related to unresolved contingencies. See Note 22 for further discussion of the Company's commitments and contingencies.
Inventory	Materials and Supplies, Fuel Stock and Stored Natural Gas Inventories of materials and supplies, fuel stock and stored natural gas are recorded at average cost for regulated operations and the lower of cost or market for non-regulated operations and consisted of the following as of December 31 (dollars in thousands): 2022 2021 Materials and supplies $ 75,766 $ 62,003 Stored natural gas 26,788 17,604 Fuel stock 5,120 5,126 Total $ 107,674 $ 84,733

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Ratio of Depreciation to Average Depreciable Property and Average Service Lives for Utility Plan in Service	For utility operations, the ratio of depreciation provisions to average depreciable property was as follows for the years ended December 31: 2022 2021 2020 Avista Utilities Ratio of depreciation to average depreciable property 3.50 % 3.54 % 3.43 % Alaska Electric Light and Power Company Ratio of depreciation to average depreciable property 2.78 % 2.77 % 2.77 % The average service lives for the following broad categories of utility plant in service are (in years): Avista Utilities Alaska Electric Light Electric thermal/other production 26 41 Hydroelectric production 79 42 Electric transmission 50 43 Electric distribution 39 39 Natural gas distribution property 44 N/A Other shorter-lived general plant 8 19 The gross balances of the major classifications of property, plant and equipment are detailed in the following table as of December 31 (dollars in thousands): 2022 2021 Avista Utilities: Electric production $ 1,593,795 $ 1,494,371 Electric transmission 994,709 945,624 Electric distribution 2,236,376 2,093,937 Electric construction work-in-progress (CWIP) and other 376,981 424,733 Electric total 5,201,861 4,958,665 Natural gas underground storage 58,072 55,684 Natural gas distribution 1,452,637 1,356,477 Natural gas CWIP and other 88,264 87,852 Natural gas total 1,598,973 1,500,013 Common plant (including CWIP) 744,173 740,339 Total Avista Utilities 7,545,007 7,199,017 AEL&P: Electric production 106,390 106,094 Electric transmission 22,856 22,691 Electric distribution 29,269 27,138 Electric CWIP and other 12,295 7,319 Electric total 170,810 163,242 Common plant 10,018 9,726 Total AEL&P 180,828 172,968 Total gross utility property 7,725,835 7,371,985 Other (1) 16,631 17,818 Total $ 7,742,466 $ 7,389,803 (1) Included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets. Accumulated depreciation was $ 2.4 million as of December 31, 2022 and $ 2.3 million as of December 31, 2021 for the other businesses.
Summary of Effective AFUDC Rate	The effective AFUDC rate was the following for the years ended December 31: 2022 2021 2020 Avista Utilities 7.12 % 7.19 % 7.25 % Alaska Electric Light and Power Company 8.08 % 8.90 % 8.04 %
Stock-Based Compensation	The Company recorded stock-based compensation expense (included in other operating expenses) and income tax benefits in the Consolidated Statements of Income of the following amounts for the years ended December 31 (dollars in thousands): 2022 2021 2020 Stock-based compensation expense $ 7,567 $ 4,713 $ 5,846 Income tax benefits 1,589 990 1,228 Excess tax expenses on settled share-based employee ( 19 ) ( 909 ) ( 165 ) The following table summarizes the number of grants, vested and unvested shares, earned shares (based on market metrics), and other pertinent information related to the Company's stock compensation awards for the years ended December 31: 2022 2021 2020 Restricted Shares Shares granted during the year 115,746 62,594 45,540 Shares vested during the year 44,829 34,854 56,203 Unvested shares at end of year 157,860 96,127 71,706 Unrecognized compensation expense at end of year $ 3,923 $ 2,215 $ 2,003 TSR Awards TSR shares granted during the year 69,814 64,910 47,848 TSR shares vested during the year 43,730 77,174 71,299 TSR shares earned based on market metrics 48,890 58,652 — Unvested TSR shares at end of year 130,567 107,854 122,133 Unrecognized compensation expense at end of year $ 3,533 $ 2,653 $ 2,296 CEPS Awards CEPS shares granted during the year 69,814 64,910 47,848 CEPS shares vested during the year 43,730 38,590 35,622 CEPS shares earned based on market metrics — 26,627 63,763 Unvested CEPS shares at end of year 130,567 107,854 83,464 Unrecognized compensation expense at end of year $ 2,471 $ 1,223 $ 1,090
Other Expense (Income) - Net	Other income - net consisted of the following items for the years ended December 31 (dollars in thousands): 2022 2021 2020 Interest income $ ( 1,957 ) $ ( 1,943 ) $ ( 1,952 ) Interest on regulatory deferrals ( 1,914 ) ( 1,206 ) ( 1,222 ) Equity-related AFUDC ( 6,704 ) ( 7,004 ) ( 6,970 ) Non-service portion of pension and other postretirement benefit ( 3,037 ) 1,386 6,433 Earnings on investments ( 48,492 ) ( 21,402 ) ( 905 ) Other income ( 613 ) ( 3,129 ) ( 201 ) Total $ ( 62,717 ) $ ( 33,298 ) $ ( 4,817 )
Allowance for Doubtful Accounts	The following table presents the activity in the allowance for doubtful accounts during the years ended December 31 (dollars in thousands): 2022 2021 2020 Allowance as of the beginning of the year $ 10,465 $ 11,387 $ 2,419 Additions expensed during the year (1) 149 9,279 11,280 Net deductions (2) ( 4,141 ) ( 10,201 ) ( 2,312 ) Allowance as of the end of the year $ 6,473 $ 10,465 $ 11,387 (1) Increases in 2021 and 2020 related to COVID-19 bad debt expense in excess of the amount recovered through rates. (2) Increase in 2021 relates to COVID forgiveness program. The Company also received support from various government agencies in 2022 in the amount of $ 6.1 million, which was applied to overdue customer accounts.
Estimated Retirement Costs Collected from Customers	The Company has recorded the amount of estimated retirement costs collected from customers (that do not represent legal or contractual obligations) and included them as a non-current regulatory liability on the Consolidated Balance Sheets in the following amounts as of December 31 (dollars in thousands): 2022 2021 Regulatory liability for utility plant retirement costs $ 376,817 $ 350,190
Summary of Changes in Carrying Amount of Goodwill	There were no changes in the carrying amount of goodwill during 2021 and 2022 and the balance was as follows (dollars in thousands): AEL&P Accumulated Impairment Losses Total Balance as of December 31, 2021 and 2022 $ 52,426 $ - $ 52,426
Summary of Appropriated Retained Earnings Amount Included in Retained Earnings	The appropriated retained earnings amounts included in retained earnings were as follows as of December 31 (dollars in thousands): 2022 2021 Appropriated retained earnings $ 57,231 $ 53,620

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Materials and Supplies, Fuel Stock and Stored Natural Gas	Inventories of materials and supplies, fuel stock and stored natural gas are recorded at average cost for regulated operations and the lower of cost or market for non-regulated operations and consisted of the following as of December 31 (dollars in thousands): 2022 2021 Materials and supplies $ 75,766 $ 62,003 Stored natural gas 26,788 17,604 Fuel stock 5,120 5,126 Total $ 107,674 $ 84,733
Schedule of Other Current Assets	Other current assets consisted of the following as of December 31 (dollars in thousands): 2022 2021 Collateral posted for derivative instruments after netting with outstanding $ 66,142 $ 21,477 Prepayments 30,201 24,387 Income taxes receivable 30,740 29,615 Derivative assets net of collateral 18,198 1,442 Other 5,886 3,833 Total $ 151,167 $ 80,754
Other Property and Investments-Net and Other Non-Current Assets	Other property and investments-net and other non-current assets consisted of the following as of December 31 (dollars in thousands): 2022 2021 Equity investments $ 147,809 $ 91,057 Operating lease ROU assets 68,238 70,133 Finance lease ROU assets 40,056 43,697 Non-utility property 25,401 20,033 Notes receivable 17,954 14,949 Long-term prepaid license fees 17,936 8,465 Pension assets 13,382 — Investment in affiliated trust 11,547 11,547 Deferred compensation assets 7,541 9,513 Other 15,221 11,149 Total $ 365,085 $ 280,543
Other Current Liabilities	Other current liabilities consisted of the following as of December 31 (dollars in thousands): 2022 2021 Accrued taxes other than income taxes $ 38,568 $ 41,706 Employee paid time off accruals 29,279 27,741 Accrued interest 20,863 17,538 Pensions and other postretirement benefits 15,625 13,582 Derivative liabilities 26,910 28,801 Deferred wholesale revenue 8,481 884 Other 49,689 38,609 Total $ 189,415 $ 168,861
Schedule of Other Non-Current Liabilities and Deferred Credits	Other non-current liabilities and deferred credits consisted of the following as of December 31 (dollars in thousands): 2022 2021 Operating lease liabilities $ 64,284 $ 66,068 Finance lease liabilities 42,495 45,730 Deferred investment tax credits 28,784 29,313 Asset retirement obligations 15,783 17,142 Derivative liabilities 7,892 4,525 Other 16,617 15,347 Total $ 175,855 $ 178,125

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Unbilled Accounts Receivable	Accounts receivable includes unbilled energy revenues of the following amounts as of December 31 (dollars in thousands): 2022 2021 Unbilled accounts receivable $ 81,691 $ 74,479
Schedule of Utilities Operating Revenue Expense Taxes	Utility-related taxes that were included in revenue from contracts with customers were as follows for the years ended December 31 (dollars in thousands): 2022 2021 2020 Utility-related taxes $ 69,931 $ 62,736 $ 59,319
Disaggregation of Revenue	Disaggregation of Total Operating Revenue The following table disaggregates total operating revenue by segment and source for the years ended December 31 (dollars in thousands): 2022 2021 2020 Avista Utilities Revenue from contracts with customers $ 1,400,027 $ 1,233,904 $ 1,157,746 Derivative revenues 286,309 152,590 110,313 Alternative revenue programs ( 33,357 ) ( 6,635 ) ( 3,814 ) Deferrals and amortizations for rate refunds to customers 207 2,984 5,335 Other utility revenues 10,629 10,156 7,888 Total Avista Utilities 1,663,815 1,392,999 1,277,468 AEL&P Revenue from contracts with customers 45,703 45,051 42,624 Deferrals and amortizations for rate refunds to customers ( 614 ) ( 190 ) ( 190 ) Other utility revenues 615 505 375 Total AEL&P 45,704 45,366 42,809 Other Revenue from contracts with customers — 2 564 Other revenues 688 569 1,050 Total Other 688 571 1,614 Total operating revenues $ 1,710,207 $ 1,438,936 $ 1,321,891 Utility Revenue from Contracts with Customers by Type and Service The following table disaggregates revenue from contracts with customers associated with the Company's electric operations for the years ended December 31 (dollars in thousands): 2022 2021 2020 Avista Utilities AEL&P Total Utility Avista Utilities AEL&P Total Utility Avista Utilities AEL&P Total Utility ELECTRIC OPERATIONS Revenue from Residential $ 414,823 $ 19,667 $ 434,490 $ 394,717 $ 18,940 $ 413,657 $ 377,785 $ 18,618 $ 396,403 Commercial and 338,656 25,782 364,438 326,173 25,861 352,034 303,972 23,754 327,726 Industrial 107,740 — 107,740 106,756 — 106,756 103,103 — 103,103 Public street and 7,483 254 7,737 7,472 250 7,722 7,303 252 7,555 Total retail 868,702 45,703 914,405 835,118 45,051 880,169 792,163 42,624 834,787 Transmission 32,307 — 32,307 21,005 — 21,005 18,236 — 18,236 Other revenue from 49,920 — 49,920 33,870 — 33,870 19,252 — 19,252 Total revenue $ 950,929 $ 45,703 $ 996,632 $ 889,993 $ 45,051 $ 935,044 $ 829,651 $ 42,624 $ 872,275 The following table disaggregates revenue from contracts with customers associated with the Company's natural gas operations for the years ended December 31 (dollars in thousands): 2022 2021 2020 Avista Utilities Avista Utilities Avista Utilities NATURAL GAS OPERATIONS Revenue from contracts with customers Residential $ 284,452 $ 221,405 $ 213,612 Commercial 139,923 100,819 94,937 Industrial and interruptible 10,471 7,796 7,128 Total retail revenue 434,846 330,020 315,677 Transportation 8,627 8,547 7,917 Other revenue from contracts with customers 5,625 5,344 4,501 Total revenue from contracts with customers $ 449,098 $ 343,911 $ 328,095

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Components of Lease Expense	The components of lease expense were as follows for the year ended December 31 (dollars in thousands): 2022 2021 Operating lease cost: Fixed lease cost (Other operating expenses) $ 4,986 $ 4,970 Variable lease cost (Other operating expenses) 1,567 1,180 Total operating lease cost $ 6,553 $ 6,150 Finance lease cost: Amortization of ROU asset (Depreciation and amortization) $ 3,641 $ 3,641 Interest on lease liabilities (Interest expense) 2,375 2,522 Total finance lease cost $ 6,016 $ 6,163
Summary of Supplemental Cash Flow Information related to Leases	Supplemental cash flow information related to leases was as follows for the year ended December 31 (dollars in thousands): 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash outflows: Operating lease payments $ 4,828 $ 4,805 Interest on finance lease 2,375 2,522 Total operating cash outflows $ 7,203 $ 7,327 Finance cash outflows: Principal payments on finance lease $ 3,085 $ 2,935
Summary of Supplemental Balance Sheet Information Related to Leases	Supplemental balance sheet information related to leases was as follows for December 31 (dollars in thousands): December 31, December 31, 2022 2021 Operating Leases Operating lease ROU assets (Other property and investments-net $ 68,238 $ 70,133 Other current liabilities $ 4,349 $ 4,301 Other non-current liabilities and deferred credits 64,284 66,068 Total operating lease liabilities $ 68,633 $ 70,369 Finance Leases Finance lease ROU assets (Other property and investments-net $ 40,056 $ 43,697 Other current liabilities $ 3,235 $ 3,085 Other non-current liabilities and deferred credits 42,495 45,730 Total finance lease liabilities $ 45,730 $ 48,815 Weighted Average Remaining Lease Term Operating leases 23.28 years 24.22 years Finance leases 5.42 years 6.32 years Weighted Average Discount Rate Operating leases 4.28 % 4.28 % Finance leases 4.07 % 4.35 %
Summary of Maturities of Lease Liabilities	Maturities of lease liabilities (including principal and interest) were as follows as of December 31, 2022 (dollars in thousands): Operating Leases Finance Leases 2023 $ 4,850 $ 5,456 2024 4,877 5,459 2025 4,884 5,454 2026 4,869 5,456 2027 4,880 5,458 Thereafter 86,991 32,748 Total lease payments $ 111,351 $ 60,031 Less: imputed interest ( 42,718 ) ( 14,301 ) Total $ 68,633 $ 45,730 Maturities of lease liabilities (including principal and interest) were as follows as of December 31, 2021 (dollars in thousands): Operating Leases Finance Leases 2022 $ 4,820 $ 5,460 2023 4,849 5,456 2024 4,875 5,459 2025 4,882 5,454 2026 4,867 5,456 Thereafter 91,845 38,204 Total lease payments $ 116,138 $ 65,489 Less: imputed interest ( 45,769 ) ( 16,674 ) Total $ 70,369 $ 48,815
Summary of Maturities of Lease Liabilities	Maturities of lease liabilities (including principal and interest) were as follows as of December 31, 2022 (dollars in thousands): Operating Leases Finance Leases 2023 $ 4,850 $ 5,456 2024 4,877 5,459 2025 4,884 5,454 2026 4,869 5,456 2027 4,880 5,458 Thereafter 86,991 32,748 Total lease payments $ 111,351 $ 60,031 Less: imputed interest ( 42,718 ) ( 14,301 ) Total $ 68,633 $ 45,730 Maturities of lease liabilities (including principal and interest) were as follows as of December 31, 2021 (dollars in thousands): Operating Leases Finance Leases 2022 $ 4,820 $ 5,460 2023 4,849 5,456 2024 4,875 5,459 2025 4,882 5,454 2026 4,867 5,456 Thereafter 91,845 38,204 Total lease payments $ 116,138 $ 65,489 Less: imputed interest ( 45,769 ) ( 16,674 ) Total $ 70,369 $ 48,815

Equity Investments (Tables)

Equity Investments (Tables)	12 Months Ended
	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Summary of Equity Investments	The following table summarizes Avista Corp.’s equity investments, which are included in “Other property and investments- net and other non-current assets” on the Consolidated Balance Sheets as of December 31 (dollars in thousands): 2022 2021 Equity method investments $ 70,196 $ 66,896 Investments without readily determinable fair value Non-recurring fair value 23,329 24,161 Recurring fair value 54,284 — Total $ 147,809 $ 91,057
Summary of Net Unrealized Gains Related to Investments without Readily Determinable Fair Value	The following table summarizes net unrealized gains related to investments without readily determinable fair value held as of the end of the respective period for the years ended December 31 (dollars in thousands): 2022 2021 2020 Investments recorded at non-recurring fair value $ 12,285 $ 8,761 $ 925 Investments recorded at recurring fair value 33,382 — — Total $ 45,667 $ 8,761 $ 925 Net unrealized gains recorded related to investments recorded at non-recurring fair value result from identified observable transactions.

Derivatives and Risk Manageme_2

Derivatives and Risk Management (Tables)	12 Months Ended
	Dec. 31, 2022
Derivative Instruments and Hedges, Assets [Abstract]
Schedule of Energy Commodity Derivative Volumes	The following table presents the underlying energy commodity derivative volumes as of December 31, 2022 that are expected to be delivered in each respective year (in thousands of MWhs and mmBTUs): Purchases Sales Electric Derivatives Gas Derivatives Electric Derivatives Gas Derivatives Year Physical (1) Financial (1) Physical (1) Financial (1) Physical (1) Financial (1) Physical (1) Financial (1) 2023 5 — 19,140 79,253 136 1,011 4,145 29,473 2024 — — 533 30,658 — — 1,370 9,668 2025 — — 450 4,895 — — 1,115 1,125 As of December 31, 2022 , there are no expected deliveries of energy commodity derivatives afte r 2 0 25. The following table presents the underlying energy commodity derivative volumes as of December 31, 2021 that were expected to be delivered in each respective year (in thousands of MWhs and mmBTUs): Purchases Sales Electric Derivatives Gas Derivatives Electric Derivatives Gas Derivatives Year Physical (1) Financial (1) Physical (1) Financial (1) Physical (1) Financial (1) Physical (1) Financial (1) 2022 129 — 7,114 61,405 234 452 3,933 31,485 2023 — — 378 23,218 — — 1,360 9,323 2024 — — 228 3,413 — — 1,370 228 2025 — — — — — — 1,115 — As of December 31, 2021 , there were no expected deliveries of energy commodity derivatives after 2 0 25. (1) Physical transactions represent commodity transactions in which Avista Corp. will take or make delivery of either electricity or natural gas; financial transactions represent derivative instruments with delivery of cash in the amount of the benefit or cost but with no physical delivery of the commodity, such as futures, swap derivatives, options, or forward contracts.
Summary of Foreign Currency Exchange Derivatives	The following table summarizes the foreign currency exchange derivatives that Avista Corp. has outstanding as of December 31 (dollars in thousands): 2022 2021 Number of contracts 19 25 Notional amount (in United States dollars) $ 8,563 $ 8,571 Notional amount (in Canadian dollars) 11,659 10,957
Summary of Unsettled Interest Rate Swap Derivatives	The following table summarizes the unsettled interest rate swap derivatives that Avista Corp. has outstanding as of the balance sheet date indicated below (dollars in thousands): Balance Sheet Date Number of Contracts Notional Amount Mandatory Cash December 31, 2022 4 $ 40,000 2023 1 10,000 2024 December 31, 2021 13 $ 140,000 2022 2 20,000 2023 1 10,000 2024
Schedules of Fair Values and Locations of Derivative Instruments	The following table presents the fair values and locations of derivative instruments recorded on the Consolidated Balance Sheets as of December 31, 2022 (dollars in thousands): Fair Value Derivative and Balance Sheet Location Gross Gross Collateral Net Asset Foreign currency exchange derivatives Other current assets $ 43 $ — $ — $ 43 Other current liabilities — ( 3 ) — ( 3 ) Interest rate swap derivatives Other current assets 8,536 — — 8,536 Other property and investments-net and other non-current assets 2,648 — — 2,648 Other current liabilities — ( 52 ) — ( 52 ) Energy commodity derivatives Other current assets 32,257 ( 22,638 ) — 9,619 Other property and investments-net and other 312 ( 16 ) — 296 Other current liabilities 107,902 ( 229,607 ) 94,850 ( 26,855 ) Other non-current liabilities and deferred credits 6,049 ( 24,530 ) 10,589 ( 7,892 ) Total derivative instruments recorded on the $ 157,704 $ ( 276,846 ) $ 105,439 $ ( 13,703 ) The following table presents the fair values and locations of derivative instruments recorded on the Consolidated Balance Sheets as of December 31, 2021 (dollars in thousands): Fair Value Derivative and Balance Sheet Location Gross Gross Collateral Net Asset Foreign currency exchange derivatives Other current liabilities $ — $ ( 19 ) $ — $ ( 19 ) Interest rate swap derivatives Other property and investments-net and other non-current assets 1,149 — — 1,149 Other current liabilities 1,170 ( 25,196 ) — ( 24,026 ) Other non-current liabilities and deferred credits — ( 78 ) — ( 78 ) Energy commodity derivatives Other current assets 1,506 ( 107 ) — 1,399 Other property and investments-net and other 6,844 ( 5,335 ) — 1,509 Other current liabilities 25,771 ( 39,616 ) 9,089 ( 4,756 ) Other non-current liabilities and deferred credits 141 ( 4,589 ) — ( 4,448 ) Total derivative instruments recorded on the $ 36,581 $ ( 74,940 ) $ 9,089 $ ( 29,270 )
Schedule of Collateral Outstanding Related to Derivative Instruments	The following table presents Avista Corp.'s collateral outstanding related to its derivative instruments as of December 31 (dollars in thousands): 2022 2021 Energy commodity derivatives Cash collateral posted $ 171,581 $ 30,567 Letters of credit outstanding 49,425 34,000 Balance sheet offsetting (cash collateral against net derivative positions) 105,439 9,089 There were no letters of credit outstanding related to interest rate swap derivatives as of December 31, 2022 and December 31, 2021. Certain of Avista Corp.’s derivative instruments contain provisions that require Avista Corp. to maintain an “investment grade” credit rating from the major credit rating agencies. If Avista Corp.’s credit ratings were to fall below “investment grade,” it would be in violation of these provisions, and the counterparties to the derivative instruments could request immediate payment or demand immediate and ongoing collateralization on derivative instruments in net liability positions. The following table presents the aggregate fair value of all derivative instruments with credit-risk-related contingent features that are in a liability position and the amount of additional collateral Avista Corp. could be required to post as of December 31 (dollars in thousands): 2022 2021 Interest rate swap derivatives Liabilities with credit-risk-related contingent features $ 52 $ 25,274 Additional collateral to post 52 25,274

Jointly Owned Electric Facili_2

Jointly Owned Electric Facilities (Tables)	12 Months Ended
	Dec. 31, 2022
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Schedule of Utility Plant in Service for Colstrip And Accumulated Depreciation	The Company’s share of utility plant in service for Colstrip and accumulated depreciation (inclusive of the ARO assets and accumulated amortization) were as follows as of December 31 (dollars in thousands): 2022 2021 Utility plant in service $ 390,852 $ 395,028 Accumulated depreciation ( 315,223 ) ( 302,220 )

Property, Plant And Equipment (

Property, Plant And Equipment (Tables)	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Schedule of Net Utility Property	Net utility property consisted of the following as of December 31 (dollars in thousands): 2022 2021 Utility plant in service $ 7,561,688 $ 7,166,580 Construction work in progress 164,147 205,405 Total 7,725,835 7,371,985 Less: Accumulated depreciation and amortization 2,281,126 2,146,470 Total net utility property $ 5,444,709 $ 5,225,515
Summary of Ratio of Depreciation to Average Depreciable Property and Average Service Lives for Utility Plan in Service	For utility operations, the ratio of depreciation provisions to average depreciable property was as follows for the years ended December 31: 2022 2021 2020 Avista Utilities Ratio of depreciation to average depreciable property 3.50 % 3.54 % 3.43 % Alaska Electric Light and Power Company Ratio of depreciation to average depreciable property 2.78 % 2.77 % 2.77 % The average service lives for the following broad categories of utility plant in service are (in years): Avista Utilities Alaska Electric Light Electric thermal/other production 26 41 Hydroelectric production 79 42 Electric transmission 50 43 Electric distribution 39 39 Natural gas distribution property 44 N/A Other shorter-lived general plant 8 19 The gross balances of the major classifications of property, plant and equipment are detailed in the following table as of December 31 (dollars in thousands): 2022 2021 Avista Utilities: Electric production $ 1,593,795 $ 1,494,371 Electric transmission 994,709 945,624 Electric distribution 2,236,376 2,093,937 Electric construction work-in-progress (CWIP) and other 376,981 424,733 Electric total 5,201,861 4,958,665 Natural gas underground storage 58,072 55,684 Natural gas distribution 1,452,637 1,356,477 Natural gas CWIP and other 88,264 87,852 Natural gas total 1,598,973 1,500,013 Common plant (including CWIP) 744,173 740,339 Total Avista Utilities 7,545,007 7,199,017 AEL&P: Electric production 106,390 106,094 Electric transmission 22,856 22,691 Electric distribution 29,269 27,138 Electric CWIP and other 12,295 7,319 Electric total 170,810 163,242 Common plant 10,018 9,726 Total AEL&P 180,828 172,968 Total gross utility property 7,725,835 7,371,985 Other (1) 16,631 17,818 Total $ 7,742,466 $ 7,389,803 (1) Included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets. Accumulated depreciation was $ 2.4 million as of December 31, 2022 and $ 2.3 million as of December 31, 2021 for the other businesses.

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2022
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in Asset Retirement Obligation	The following table documents the changes in the Company’s asset retirement obligation during the years ended December 31 (dollars in thousands): 2022 2021 2020 Asset retirement obligation at beginning of year $ 17,142 $ 17,194 $ 20,338 Liabilities incurred — 825 ( 2,315 ) Liabilities settled ( 1,964 ) ( 1,541 ) ( 1,645 ) Accretion expense 605 664 816 Asset retirement obligation at end of year $ 15,783 $ 17,142 $ 17,194

Pension Plans and Other Postr_2

Pension Plans and Other Postretirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2022
Change in Benefit Obligation and Plan Assets	The following table sets forth the pension and other postretirement benefit plan disclosures as of December 31, 2022 and 2021 and the components of net periodic benefit costs for the years ended December 31, 2022, 2021 and 2020 (dollars in thousands): Pension Benefits Other Post- 2022 2021 2022 2021 Change in benefit obligation: Benefit obligation as of beginning of year $ 799,042 $ 826,915 $ 167,598 $ 161,233 Service cost 23,877 25,306 4,369 4,114 Interest cost 26,536 26,160 5,503 5,139 Actuarial (gain)/loss ( 204,775 ) ( 13,997 ) ( 54,120 ) 2,808 Plan change 3,302 — — — Settlement ( 60,206 ) — — — Benefits paid ( 30,067 ) ( 65,342 ) ( 7,715 ) ( 5,696 ) Benefit obligation as of end of year $ 557,709 $ 799,042 $ 115,635 $ 167,598 Change in plan assets: Fair value of plan assets as of beginning of year $ 750,963 $ 722,024 $ 59,544 $ 52,173 Actual return on plan assets ( 163,866 ) 50,370 ( 10,072 ) 7,371 Employer contributions 42,000 42,000 — — Settlement ( 60,206 ) — — — Benefits paid ( 28,188 ) ( 63,431 ) — — Fair value of plan assets as of end of year $ 540,703 $ 750,963 $ 49,472 $ 59,544 Funded status $ ( 17,006 ) $ ( 48,079 ) $ ( 66,163 ) $ ( 108,054 ) Amounts recognized in the Consolidated Balance Sheets: Other non-current assets $ 13,382 $ — $ — $ — Other current liabilities ( 1,934 ) ( 1,951 ) ( 706 ) ( 684 ) Non-current liabilities ( 28,454 ) ( 46,128 ) ( 65,457 ) ( 107,370 ) Net amount recognized $ ( 17,006 ) $ ( 48,079 ) $ ( 66,163 ) $ ( 108,054 ) Accumulated pension benefit obligation $ 495,654 $ 685,493 Accumulated postretirement benefit obligation: For retirees $ 61,984 $ 78,347 For fully eligible employees $ 19,731 $ 32,144 For other participants $ 33,920 $ 57,107 Included in accumulated other comprehensive loss (income) (net of tax): Unrecognized prior service cost (credit) $ 4,105 $ 1,699 $ ( 1,911 ) $ ( 2,741 ) Unrecognized net actuarial loss 83,794 94,109 13,643 48,872 Total 87,899 95,808 11,732 46,131 Less regulatory asset ( 85,198 ) ( 85,550 ) ( 12,375 ) ( 45,350 ) Accumulated other comprehensive loss for unfunded benefit $ 2,701 $ 10,258 $ ( 643 ) $ 781 Pension Benefits Other Post- 2022 2021 2022 2021 Weighted-average assumptions as of December 31: Discount rate for benefit obligation 6.10 % 3.39 % 6.10 % 3.40 % Discount rate for annual expense 3.39 % 3.25 % 3.40 % 3.27 % Expected long-term return on plan assets 5.80 % 5.40 % 4.70 % 4.60 % Rate of compensation increase 4.69 % 4.66 % Medical cost trend pre-age 65 – initial 6.25 % 6.00 % Medical cost trend pre-age 65 – ultimate 5.00 % 5.00 % Ultimate medical cost trend year pre-age 65 2028 2026 Medical cost trend post-age 65 – initial 6.25 % 6.00 % Medical cost trend post-age 65 – ultimate 5.00 % 5.00 % Ultimate medical cost trend year post-age 65 2028 2026
Components of Net Periodic Benefit Cost	Pension Benefits Other Post-retirement Benefits 2022 2021 2020 2022 2021 2020 Components of net periodic benefit cost: Service cost (1) $ 23,877 $ 25,306 $ 22,392 $ 4,369 $ 4,114 $ 3,902 Interest cost 26,536 26,160 27,853 5,503 5,139 6,042 Expected return on plan assets ( 43,872 ) ( 39,088 ) ( 34,886 ) ( 2,799 ) ( 2,400 ) ( 2,377 ) Amortization of prior service cost (credit) 257 257 257 ( 1,050 ) ( 921 ) ( 958 ) Net loss recognition 4,180 6,645 6,717 3,344 3,865 4,871 Settlement loss (2) 11,828 — — — — — Net periodic benefit cost $ 22,806 $ 19,280 $ 22,333 $ 9,367 $ 9,797 $ 11,480 (1) Total service costs in the table above are recorded to the same accounts as labor expense. Labor and benefits expense is recorded to various projects based on whether the work is a capital project or an operating expense. Approximately 40 percent of all labor and benefits is capitalized to utility property and 60 percent is expensed to utility other operating expenses. (2) The settlement loss was deferred as a regulatory asset to be amortized over future periods.
Schedule of Allocation of Plan Assets	The target investment allocation percentages by asset classes are indicated in the table below: 2022 2021 Equity securities 55 % 55 % Debt securities 40 % 40 % Real estate 5 % 5 % Absolute return 0 % 0 %
Employer Matching Contributions	Employer matching contributions were as follows for the years ended December 31 (dollars in thousands): 2022 2021 2020 Employer 401(k) matching contributions $ 13,258 $ 11,671 $ 11,742
Deferred Compensation Assets and Liabilities	There were deferred compensation assets included in other property and investments-net and corresponding deferred compensation liabilities included in other non-current liabilities and deferred credits on the Consolidated Balance Sheets of the following amounts as of December 31 (dollars in thousands): 2022 2021 Deferred compensation assets and liabilities $ 7,541 $ 9,513
Pension Plan And SERP [Member]
Schedule of Expected Benefit Payments	The Company expects that benefit payments under the pension plan and the SERP will total (dollars in thousands): 2023 2024 2025 2026 2027 Total 2028- Expected benefit payments $ 41,993 $ 41,759 $ 42,207 $ 42,517 $ 43,037 $ 226,781
Schedule of Allocation of Plan Assets	The following table discloses by level within the fair value hierarchy (see Note 18 for a description of the fair value hierarchy) of the pension plan’s assets measured and reported as of December 31, 2022 at fair value (dollars in thousands): Level 1 Level 2 Level 3 Total Cash equivalents $ — $ 5,110 $ — $ 5,110 Fixed income securities: U.S. government issues — 16,732 — 16,732 Corporate issues — 161,180 — 161,180 International issues — 23,108 — 23,108 Municipal issues — 13,427 — 13,427 Mutual funds: U.S. equity securities 154,442 — — 154,442 International equity securities 58,933 — — 58,933 Plan assets measured at NAV (not subject to hierarchy Common/collective trusts: Real estate — — — 30,406 Partnership/closely held investments: International equity securities — — — 69,792 Real estate — — — 7,573 Total $ 213,375 $ 219,557 $ — $ 540,703 The following table discloses by level within the fair value hierarchy (see Note 18 for a description of the fair value hierarchy) of the pension plan’s assets measured and reported as of December 31, 2021 at fair value (dollars in thousands): Level 1 Level 2 Level 3 Total Cash equivalents $ — $ 6,259 $ — $ 6,259 Fixed income securities: U.S. government issues — 19,310 — 19,310 Corporate issues — 233,496 — 233,496 International issues — 34,270 — 34,270 Municipal issues — 18,558 — 18,558 Mutual funds: U.S. equity securities 236,552 — — 236,552 International equity securities 112,873 — — 112,873 Plan assets measured at NAV (not subject to hierarchy Common/collective trusts: Real estate — — — 31,040 Partnership/closely held investments: Absolute return — — — 363 International equity securities — — — 50,427 Real estate — — — 7,815 Total $ 349,425 $ 311,893 $ — $ 750,963
Other Postretirement Benefits [Member]
Schedule of Expected Benefit Payments	The Company expects that benefit payments under other postretirement benefit plans will total (dollars in thousands): 2023 2024 2025 2026 2027 Total 2028- Expected benefit payments $ 7,031 $ 7,234 $ 7,436 $ 7,585 $ 7,771 $ 40,959
Schedule of Allocation of Plan Assets	The following table discloses by level within the fair value hierarchy (see Note 18 for a description of the fair value hierarchy) of other postretirement plan assets measured and reported as of December 31, 2022 at fair value (dollars in thousands): Level 1 Level 2 Level 3 Total Balanced index mutual fund (1) $ 49,472 $ — $ — $ 49,472 The following table discloses by level within the fair value hierarchy (see Note 18 for a description of the fair value hierarchy) of other postretirement plan assets measured and reported as of December 31, 2021 at fair value (dollars in thousands): Level 1 Level 2 Level 3 Total Balanced index mutual fund (1) $ 59,545 $ — $ — $ 59,545 (1) The balanced index fund for 2022 and 2021 is a single mutual fund that includes a percentage of U.S. equity and fixed income securities and International equity and fixed income securities.

Accounting For Income Taxes (Ta

Accounting For Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense	Income tax expense consisted of the following for the years ended December 31 (dollars in thousands): 2022 2021 2020 Current income tax expense (benefit) $ 1,040 $ 807 $ ( 37,913 ) Deferred income tax expense (benefit) ( 18,231 ) 11,224 44,964 Total income tax expense (benefit) $ ( 17,191 ) $ 12,031 $ 7,051
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of federal income taxes derived from the statutory federal tax rate of 21 percent applied to income before income taxes is as follows for the years ended December 31 (dollars in thousands): 2022 2021 2020 Federal income taxes at statutory rates $ 28,977 21.0 % $ 33,467 21.0 % $ 28,673 21.0 % Increase (decrease) in tax resulting from: Tax effect of regulatory treatment of utility ( 12,366 ) ( 9.0 ) ( 13,820 ) ( 8.7 ) ( 12,893 ) ( 9.4 ) State income tax expense 1,676 1.2 1,385 0.8 814 0.6 Flow through related to deduction of meters ( 34,454 ) ( 25.0 ) ( 8,678 ) ( 5.4 ) — — Non-plant excess deferred turnaround (3) — — — — ( 8,476 ) ( 6.2 ) Customer refunds related to prior years at 35 percent — — — — ( 1,189 ) ( 0.9 ) Other ( 1,024 ) ( 0.7 ) ( 323 ) ( 0.2 ) 122 0.1 Total income tax expense (benefit) $ ( 17,191 ) ( 12.5 )% $ 12,031 7.5 % $ 7,051 5.2 % (1) Prior to 2022, for the depreciation-related temporary differences under the normalization tax accounting method, the Company utilized the average rate assumption method to compute the amounts returned to customers. Beginning in 2022, the Company changed to the alternative method, to be in compliance with recently released revenue procedures and private letter rulings. (2) During 2021 and 2022, new rates from the Company's Idaho, Oregon and Washington general rate cases went into effect with base rate increases offset by customer tax credits. As the customer tax credits are returned to customers, this results in a decrease to income tax expense as a result of flowing through the benefits related to meters and mixed service costs. This decrease in income tax expense offsets the increases in base rate granted to the Company in these general rate cases. (3) As part of a settlement agreement in a Washington general rate case, the parties agreed to utilize $ 10.9 million ($ 8.4 million when tax-effected) of the electric benefits to offset costs associated with accelerating the depreciation of Colstrip, to reflect a remaining useful life through December 31, 2025.
Schedule of Deferred Income Tax Assets and Liabilities	The total net deferred income tax liability consisted of the following as of December 31 (dollars in thousands): 2022 2021 Deferred income tax assets: Regulatory liabilities $ 197,998 $ 200,513 Tax credits and NOL carryforwards 74,782 64,994 Provisions for pensions 20,132 25,650 Other 54,903 38,181 Total gross deferred income tax assets 347,815 329,338 Valuation allowances for deferred tax assets ( 3,874 ) ( 9,626 ) Total deferred income tax assets after valuation allowances 343,941 319,712 Deferred income tax liabilities: Utility property, plant, and equipment 712,470 688,856 Regulatory assets 281,483 264,978 Other 24,983 8,587 Total deferred income tax liabilities 1,018,936 962,421 Net long-term deferred income tax liability $ 674,995 $ 642,709

Energy Purchase Contracts (Tabl

Energy Purchase Contracts (Tables)	12 Months Ended
	Dec. 31, 2022
Energy Purchase Contracts [Line Items]
Schedule of Utility Total Expenses	Total expenses for power purchased, natural gas purchased, fuel for generation and other fuel costs, which are included in utility resource costs in the Consolidated Statements of Income, were as follows for the years ended December 31 (dollars in thousands): 2022 2021 2020 Utility power resources $ 660,967 $ 431,199 $ 324,297
Future Contractual Commitments for Power Resources and Natural Gas Resources	The following table details Avista Utilities’ future contractual commitments for power resources (including transmission contracts) and natural gas resources (including transportation contracts) (dollars in thousands): 2023 2024 2025 2026 2027 Thereafter Total Power resources $ 245,169 $ 215,044 $ 240,214 $ 214,747 $ 185,590 $ 2,333,955 $ 3,434,719 Natural gas resources 130,921 79,366 39,192 28,046 38,591 320,377 636,493 Total $ 376,090 $ 294,410 $ 279,406 $ 242,793 $ 224,181 $ 2,654,332 $ 4,071,212
Contractual Obligations [Member]
Energy Purchase Contracts [Line Items]
Future Contractual Commitments for Power Resources and Natural Gas Resources	The following table details future contractual commitments under these agreements (dollars in thousands): 2023 2024 2025 2026 2027 Thereafter Total Contractual obligations $ 30,562 $ 31,416 $ 32,255 $ 16,937 $ 17,343 $ 178,193 $ 306,706

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2022
Avista Utilities [Member]
Line of Credit Facility [Line Items]
Schedule of Balances Outstanding and Interest Rates of Borrowings	Balances outstanding and interest rates of borrowings (excluding letters of credit) under the Company’s $ 400 million revolving committed line of credit due in June 2026 were as follows as of December 31 (dollars in thousands): 2022 2021 Balance outstanding at end of period $ 313,000 $ 284,000 Letters of credit outstanding at end of period 35,563 34,000 Average interest rate at end of period 5.31 % 1.11 % As of December 31, 2022 , the Company did no t have any outstanding borrowings under the $ 100 million revolving credit agreement due in November 2023.

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2022
Long-Term Debt, Unclassified [Abstract]
Schedule of Long-term Debt Instruments	Maturity Description Interest 2022 2021 Avista Corp. Secured Long-Term Debt 2022 First Mortgage Bonds 5.13 % $ — $ 250,000 2023 Secured Medium-Term Notes 7.18 %- 7.54 % 13,500 13,500 2028 Secured Medium-Term Notes 6.37 % 25,000 25,000 2032 Secured Pollution Control Bonds (1) (1) 66,700 66,700 2034 Secured Pollution Control Bonds (1) (1) 17,000 17,000 2035 First Mortgage Bonds 6.25 % 150,000 150,000 2037 First Mortgage Bonds 5.70 % 150,000 150,000 2040 First Mortgage Bonds 5.55 % 35,000 35,000 2041 First Mortgage Bonds 4.45 % 85,000 85,000 2044 First Mortgage Bonds 4.11 % 60,000 60,000 2045 First Mortgage Bonds 4.37 % 100,000 100,000 2047 First Mortgage Bonds 4.23 % 80,000 80,000 2047 First Mortgage Bonds 3.91 % 90,000 90,000 2048 First Mortgage Bonds 4.35 % 375,000 375,000 2049 First Mortgage Bonds 3.43 % 180,000 180,000 2050 First Mortgage Bonds 3.07 % 165,000 165,000 2051 First Mortgage Bonds 3.54 % 175,000 175,000 2051 First Mortgage Bonds 2.90 % 140,000 140,000 2052 First Mortgage Bonds (2) 4.00 % 400,000 — Total Avista Corp. secured long-term debt 2,307,200 2,157,200 Alaska Electric Light and Power Company Secured Long-Term Debt 2044 First Mortgage Bonds 4.54 % 75,000 75,000 Total secured long-term debt 2,382,200 2,232,200 Alaska Energy and Resources Company Unsecured Long-Term Debt 2024 Unsecured Term Loan 3.44 % 15,000 15,000 Total secured and unsecured long-term debt 2,397,200 2,247,200 Other Long-Term Debt Components Unamortized debt discount ( 726 ) ( 632 ) Unamortized long-term debt issuance costs ( 18,261 ) ( 14,498 ) Total 2,378,213 2,232,070 Secured Pollution Control Bonds held by Avista ( 83,700 ) ( 83,700 ) Current portion of long-term debt ( 13,500 ) ( 250,000 ) Total long-term debt $ 2,281,013 $ 1,898,370 (1) In December 2010, $ 66.7 million and $ 17.0 million of the City of Forsyth, Montana Pollution Control Revenue Refunding Bonds (Avista Corporation Colstrip Project) due in 2032 and 2034, respectively, which had been held by Avista Corp. since 2008 and 2009, respectively, were refunded by new variable rate bond issues. The new bonds were not offered to the public and were purchased by Avista Corp. due to market conditions. The Company has the ability to remarket these bonds to unaffiliated investors at a later date, subject to market conditions. So long as Avista Corp. is the holder of these bonds, the bonds will not be reflected as an asset or a liability on the Consolidated Balance Sheets. (2) In March 2022, the Company issued and sold $ 400.0 million of 4.00 percent first mortgage bonds due in 2052 through a public offering. The total net proceeds from the sale of the bonds were used to repay the borrowings outstanding under Avista Corp.'s $ 400.0 million committed line of credit, as well as $ 250.0 million of maturing debt. In connection with the pricing of the first mortgage bonds in March 2022, the Company cash settled thirteen interest rate swap derivatives (notional aggregate amount of $ 140.0 million) and paid a net amount of $ 17.0 million. See Note 8 for a discussion of interest rate swap derivatives.
Schedule of Maturities of Long-term Debt	2023 2024 2025 2026 2027 Thereafter Total Debt maturities $ 13,500 $ 15,000 $ — $ — $ — $ 2,336,547 $ 2,365,047

Long-Term Debt to Affiliated _2

Long-Term Debt to Affiliated Trusts (Tables)	12 Months Ended
	Dec. 31, 2022
Long Term Debt To Affiliated Trust [Abstract]
Schedule of Distribution Rates Paid	The distribution rates paid were as follows during the years ended December 31: 2022 2021 2020 Low distribution rate 1.05 % 0.99 % 1.10 % High distribution rate 5.64 % 1.10 % 2.79 % Distribution rate at the end of the year 5.64 % 1.05 % 1.10 %

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Schedule of Carrying Value and Estimated Fair Value of Financial Instruments	The following table sets forth the carrying value and estimated fair value of the Company’s financial instruments not reported at estimated fair value on the Consolidated Balance Sheets as of December 31 (dollars in thousands): 2022 2021 Carrying Estimated Carrying Estimated Long-term debt (Level 2) $ 1,113,500 $ 966,881 $ 963,500 $ 1,157,651 Long-term debt (Level 3) 1,200,000 881,480 1,200,000 1,366,619 Snettisham finance lease obligation (Level 3) 45,730 41,700 48,815 54,000 Long-term debt to affiliated trusts (Level 3) 51,547 42,836 51,547 43,299
Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis	The following table discloses by level within the fair value hierarchy the Company’s assets and liabilities measured and reported on the Consolidated Balance Sheets as of December 31, 2022 at fair value on a recurring basis (dollars in thousands): Level 1 Level 2 Level 3 Counterparty Total December 31, 2022 Assets: Energy commodity derivatives (2) $ — $ 146,232 $ 288 $ ( 136,605 ) $ 9,915 Foreign currency exchange derivatives — 43 — — 43 Interest rate swap derivatives — 11,184 — — 11,184 Equity investments (3) — — 54,284 — 54,284 Deferred compensation assets: Mutual Funds: Fixed income securities (3) 1,267 — — — 1,267 Equity securities (3) 6,132 — — — 6,132 Total $ 7,399 $ 157,459 $ 54,572 $ ( 136,605 ) $ 82,825 Liabilities: Energy commodity derivatives (2) $ — $ 258,769 $ 18,022 $ ( 242,044 ) $ 34,747 Foreign currency exchang e derivatives — 3 — — 3 Interest rate swap derivatives — 52 — — 52 Total $ — $ 258,824 $ 18,022 $ ( 242,044 ) $ 34,802 The following table discloses by level within the fair value hierarchy the Company’s assets and liabilities measured and reported on the Consolidated Balance Sheets as of December 31, 2021 at fair value on a recurring basis (dollars in thousands): Level 1 Level 2 Level 3 Counterparty Total December 31, 2021 Assets: Energy commodity derivatives (2) $ — $ 34,119 $ 143 $ ( 31,354 ) $ 2,908 Interest rate swap derivatives — 2,319 — ( 1,170 ) 1,149 Deferred compensation assets: Mutual Funds: Fixed income securities (3) 1,809 — — — 1,809 Equity securities (3) 7,594 — — — 7,594 Total $ 9,403 $ 36,438 $ 143 $ ( 32,524 ) $ 13,460 Liabilities: Energy commodity derivatives (2) $ — $ 41,733 $ 7,914 $ ( 40,443 ) $ 9,204 Foreign currency exchange derivatives — 19 — — 19 Interest rate swap derivatives — 25,274 — ( 1,170 ) 24,104 Total $ — $ 67,026 $ 7,914 $ ( 41,613 ) $ 33,327 (1) The Company is permitted to net derivative assets and derivative liabilities with the same counterparty when a legally enforceable master netting agreement exists. In addition, the Company nets derivative assets and derivative liabilities against any payables and receivables for cash collateral held or placed with these same counterparties. (2) The level 3 energy commodity derivative balances are associated with natural gas exchange agreements (3) These assets are included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets.
Schedule of Quantitative Information	The following table presents the quantitative information which was used to estimate the fair values of the Level 3 assets and liabilities above as of December 31, 2022 (dollars in thousands): Fair Value (Net) at December 31, 2022 Valuation Technique Unobservable Input Range Natural gas exchange $ ( 17,734 ) Internally derived Forward purchase prices $ 2.89 - $ 4.19 /mmBTU 3.47 Weighted Average Forward sales prices $ 3.11 - $ 23.47 /mmBTU 8.88 Weighted Average Purchase volumes 140,000 - 370,000 mmBTUs Sales volumes 75,000 - 310,000 mmBTUs Fair Value at December 31, 2022 Valuation Technique Unobservable Input Range Equity investments $ 54,284 Market approach Comparable enterprise values $ 130,000 -$ 388,600 246,000 Average Time to liquidity event 2 years Marketability discount 30 % Discounted cash flows Revenue market multiples 1.44 x to 6.55 x Revenue 2.88 x Average Market multiple reduction 30 % to 50 % 40 % Average Discount rate 25 % Revenue market multiples $ 4,000 -$ 337,000 Terminal date 2024
Schedule of Activity For Energy Commodity Derivative Assets (Liabilities) Measured At Fair Value Using Significant Unobservable Inputs (Level 3)	The following table presents activity for assets and liabilities measured at fair value using significant unobservable inputs (Level 3) for the years ended December 31 (dollars in thousands): Natural Gas Exchange Agreement (1) Equity Investments Total Year ended December 31, 2022: Balance as of January 1, 2022 $ ( 7,771 ) $ — $ ( 7,771 ) Transfers in (2) — 20,902 20,902 Total gains or (losses) (realized/unrealized): Included in regulatory assets ( 4,740 ) — ( 4,740 ) Recognized in net income — 33,382 33,382 Settlements ( 5,223 ) — ( 5,223 ) Ending balance as of December 31, 2022 $ ( 17,734 ) $ 54,284 $ 36,550 Year ended December 31, 2021: Balance as of January 1, 2021 $ ( 8,410 ) $ — $ ( 8,410 ) Total gains or (losses) (realized/unrealized): Included in regulatory assets 4,292 — 4,292 Settlements ( 3,653 ) — ( 3,653 ) Ending balance as of December 31, 2021 $ ( 7,771 ) $ — $ ( 7,771 ) Year ended December 31, 2020: Balance as of January 1, 2020 $ ( 2,976 ) $ — $ ( 2,976 ) Total gains or (losses) (realized/unrealized): Included in regulatory assets ( 4,311 ) — ( 4,311 ) Settlements ( 1,123 ) — ( 1,123 ) Ending balance as of December 31, 2020 $ ( 8,410 ) $ — $ ( 8,410 ) (1) There were no purchases, issuances or transfers from other categories of any derivatives instruments during the periods presented in the table above. (2) The Company elected to account for certain equity investments at recurring fair value in 2022, as such the transfer in represents the value as of the election. See further discussion within Note 7 .

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2022
Accumulated Other Comprehensive Loss [Abstract]
Schedule of Accumulated Other Comprehensive Loss, Net of Tax	Accumulated other comprehensive loss, net of tax, consisted of the following as of December 31 (dollars in thousands): 2022 2021 Unfunded benefit obligation for pensions and other postretirement benefit 547 and $ 2,934 , respectively $ 2,058 $ 11,039
Reclassification out of Accumulated Other Comprehensive Loss	The following table details the reclassifications out of accumulated other comprehensive loss by component for the years ended December 31 (dollars in thousands): Amounts Reclassified from Accumulated Other Details about Accumulated Other Comprehensive Loss Components 2022 2021 2020 Amortization of defined benefit pension items Amortization of net prior service cost (a) $ ( 4,095 ) $ ( 793 ) $ ( 794 ) Amortization of net loss (a) 57,650 38,070 5,586 Adjustment due to effects of regulation (a) ( 42,187 ) ( 33,050 ) ( 10,006 ) Total before tax (b) 11,368 4,227 ( 5,214 ) Tax expense (b) ( 2,387 ) ( 888 ) 1,095 Net of tax (b) $ 8,981 $ 3,339 $ ( 4,119 ) (a) These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 12 for additional details). (b) Description is also the affected line item on the Consolidated Statements of Income

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Earnings Per Common Share	The following table presents the computation of basic and diluted earnings per common share for the years ended December 31 (dollars and shares in thousands, except per share amounts): 2022 2021 2020 Numerator: Net income $ 155,176 $ 147,334 $ 129,488 Denominator: Weighted-average number of common shares outstanding-basic 72,989 69,951 67,962 Effect of dilutive securities: Performance and restricted stock awards 104 134 140 Weighted-average number of common shares outstanding-diluted 73,093 70,085 68,102 Earnings per common share: Basic $ 2.13 $ 2.11 $ 1.91 Diluted $ 2.12 $ 2.10 $ 1.90

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Ownership and Operating Ownership Interest Percentage	Colstrip Units 3 and 4 are owned by the Company, PacifiCorp, Portland General Electric (PGE), and Puget Sound Energy (PSE) (collectively, the “Western Co-Owners”), as well as NorthWestern and Talen Montana, LLC (Talen), as tenants in common under an Ownership and Operating Agreement, dated May 6, 1981, as amended (O&O Agreement), in the percentages set forth below: Co-Owner Unit 3 Unit 4 Avista 15 % 15 % PacifiCorp 10 % 10 % PGE 20 % 20 % PSE 25 % 25 % NorthWestern — 30 % Talen 30 % —

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2022
Regulated Operations [Abstract]
Schedule of Regulatory Assets and Liabilities	The following table presents the Company’s regulatory assets and liabilities as of December 31, 2022 (dollars in thousands): Receiving 2022 2021 Remaining (1) Not (2) Current Non- Current Non- Regulatory Assets: Deferred income tax (3 ) $ 240,325 $ — $ — $ — $ 240,325 $ — $ 244,154 Pensions and other (4 ) — 135,337 — — 135,337 — 165,696 Energy commodity (5 ) — 130,275 — 112,090 18,185 12,447 2,938 Unamortized debt repurchase (6 ) 6,177 — — — 6,177 — 6,768 Settlement with 2059 37,809 — — — 37,809 — 38,926 Demand side management (3 ) — 3,683 — — 3,683 — 3,974 Decoupling surcharge 2025 11,699 — — 6,250 5,449 9,907 14,625 Utility plant abandoned (7 ) 24,389 — — — 24,389 — 26,771 Interest rate swaps (8 ) 168,832 — 17,087 — 185,919 — 199,754 Deferred power costs (3 ) 47,399 — — 23,356 24,043 7,334 3,501 Deferred natural gas costs (3 ) 52,091 — — 52,091 — 14,095 6,932 AFUDC above FERC (11 ) 51,649 — — — 51,649 — 48,455 COVID-19 deferrals (12 ) — 1,650 8,143 — 9,793 — 13,591 Advanced meter infrastructure (13 ) 32,381 — — — 32,381 — 36,008 Other regulatory assets (3 ) 40,163 14,871 3,155 — 58,189 — 48,533 Total regulatory assets $ 712,914 $ 285,816 $ 28,385 $ 193,787 $ 833,328 $ 43,783 $ 860,626 Regulatory Liabilities: Deferred power costs (3 ) $ — $ — $ — $ — $ — $ 6,457 $ 5,434 Utility plant retirement costs (9 ) 376,817 — — — 376,817 — 350,190 Income tax related liabilities (3) (10) 427,365 27,458 9,178 73,267 390,734 56,331 458,789 Interest rate swaps (8 ) 13,020 — 11,184 — 24,204 — 15,062 Decoupling rebate 2025 29,945 — — 9,469 20,476 3,049 6,259 COVID-19 deferrals (12 ) — 1,227 10,647 — 11,874 — 12,500 Other regulatory liabilities (3 ) 6,718 22,943 — 12,929 16,732 11,312 13,281 Total regulatory liabilities $ 853,865 $ 51,628 $ 31,009 $ 95,665 $ 840,837 $ 77,149 $ 861,515 (1) Earning a return includes either interest on the regulatory asset/liability or a return on the investment as a component of rate base at the allowed rate of return. (2) Expected recovery is pending regulatory treatment including regulatory assets and liabilities with prior regulatory precedence. (3) Remaining amortization period varies depending on timing of underlying transactions. (4) As the Company has historically recovered and currently recovers its pension and other postretirement benefit costs related to its regulated operations in retail rates, the Company records a regulatory asset for that portion of its pension and other postretirement benefit funding deficiency. (5) The WUTC and the IPUC issued accounting orders authorizing Avista Corp. to offset energy commodity derivative assets or liabilities with a regulatory asset or liability. This accounting treatment is intended to defer the recognition of mark-to-market gains and losses on energy commodity transactions until the period of delivery. Realized benefits and losses result in adjustments to retail rates through PGAs, the ERM in Washington, the PCA mechanism in Idaho and periodic general rates cases. The resulting regulatory assets associated with energy commodity derivative instruments have been concluded to be probable of recovery through future rates. (6) Premiums paid or discounts received to repurchase debt are amortized over the remaining life of the original debt that was repurchased or, if new debt is issued in connection with the repurchase, these costs are amortized over the life of the new debt. These costs are recovered through retail rates as a component of interest expense. (7) The WUTC approved recovery of AMI project costs through the 2020 general rate case settlements, including amortization of retired meters replaced through the project through 2033. There are additional smaller projects included in the balance that the Company expects to fully recover, which have not yet been through the regulatory process. (8) For interest rate swap derivatives, Avista Corp. records all mark-to-market gains and losses in each accounting period as assets and liabilities, as well as offsetting regulatory assets and liabilities, such that there is no income statement impact. The interest rate swap derivatives are risk management tools similar to energy commodity derivatives. Upon settlement of interest rate swap derivatives, the regulatory asset or liability is amortized as a component of interest expense over the term of the associated debt. The Company records an offset of interest rate swap derivative assets and liabilities with regulatory assets and liabilities, based on the prior practice of the commissions to provide recovery through the ratemaking process. Settled interest rate swap derivatives which have been through a general rate case proceeding are classified as earning a return in the table above, whereas all unsettled interest rate swap derivatives and settled interest rate swap derivatives which have not been included in a general rate case are classified as expected recovery. (9) This amount is dependent upon the cost of removal of underlying utility plant assets and the life of utility plant. (10) The majority of this balance represents amounts due back to customers and resulted from the Tax Cuts and Jobs Act signed into law in December 2017, which changed the federal income tax rate from 35 percent to 21 percent. The Company revalued all deferred income taxes as of December 31, 2017. The Company expects the amounts for utility plant items for Avista Utilities to be returned to customers over a period of approximately 33 years . The Company expects the AEL&P amounts to be returned to customers over a period of approximately 22 years. Prior to 2022, for depreciation-related temporary differences under the normalized tax accounting method, the Company utilized the average rate assumption method to compute the amounts returned to customers. Beginning in 2022, the Company changed to the alternative method, to be in compliance with recently released revenue procedures and private letter rulings. (11) This amount is being amortized based on the underlying utility plant assets and the life of utility plant. (12) The WUTC, IPUC and OPUC issued accounting orders allowing the Company to defer certain costs, net of any benefits, related to the COVID-19 pandemic. The Company has recorded all benefits on a gross basis as a regulatory liability to customers and all additional allowed costs are a regulatory asset. The ratemaking treatment will be determined in future general rate cases in each jurisdiction. (13) This amount represents the deferral of the depreciation expense of the Company’s AMI project in Washington state. Recovery of these amounts was approved by WUTC in the 2021 general rate case order, and the asset will be amortized through 2033.
Schedule of Decoupling and Earnings Sharing Mechanisms	As of December 31, 2022 and December 31, 2021, the Company had the following cumulative balances outstanding related to decoupling and earnings sharing mechanisms in its various jurisdictions (dollars in thousands): December 31, December 31, 2022 2021 Washington Decoupling (rebate) surcharge $ ( 13,210 ) $ 13,522 Idaho Decoupling rebate $ ( 7,889 ) $ ( 1,450 ) Provision for earnings sharing rebate ( 686 ) ( 686 ) Oregon Decoupling surcharge $ 2,853 $ 3,152

Information by Business Segme_2

Information by Business Segments (Tables)	12 Months Ended
	Dec. 31, 2022
Segment Reporting [Abstract]
Schedule of Business Segments	The following table presents information for each of the Company’s business segments (dollars in thousands): Avista Alaska Total Utility Other Intersegment Total For the year ended Operating revenues $ 1,663,815 $ 45,704 $ 1,709,519 $ 688 $ — $ 1,710,207 Resource costs 732,298 3,564 735,862 — — 735,862 Other operating expenses 390,597 14,568 405,165 11,603 — 416,768 Depreciation and amortization 242,198 10,819 253,017 125 — 253,142 Income (loss) from operations 185,582 15,700 201,282 ( 11,040 ) — 190,242 Interest expense (2) 112,213 5,960 118,173 791 ( 272 ) 118,692 Income taxes ( 27,368 ) 2,337 ( 25,031 ) 7,840 — ( 17,191 ) Net income 117,901 7,545 125,446 29,730 — 155,176 Capital expenditures (3) 443,373 8,622 451,995 834 — 452,829 For the year ended Operating revenues $ 1,392,999 $ 45,366 $ 1,438,365 $ 571 $ — $ 1,438,936 Resource costs 493,289 3,834 497,123 — — 497,123 Other operating expenses 352,241 13,884 366,125 5,927 — 372,052 Depreciation and amortization 221,552 10,363 231,915 261 — 232,176 Income (loss) from operations 217,663 16,186 233,849 ( 5,617 ) — 228,232 Interest expense (2) 99,629 6,096 105,725 522 ( 95 ) 106,152 Income taxes 6,029 2,763 8,792 3,239 — 12,031 Net income 125,558 7,224 132,782 14,552 — 147,334 Capital expenditures (3) 435,887 4,052 439,939 1,270 — 441,209 For the year ended Operating revenues $ 1,277,468 $ 42,809 $ 1,320,277 $ 1,614 $ — $ 1,321,891 Resource costs 396,543 1,966 398,509 — — 398,509 Other operating expenses 341,709 12,905 354,614 5,344 — 359,958 Depreciation and amortization 213,701 9,806 223,507 716 — 224,223 Income (loss) from operations 220,058 17,088 237,146 ( 4,446 ) — 232,700 Interest expense (2) 98,451 6,272 104,723 524 ( 186 ) 105,061 Income taxes 4,921 3,011 7,932 ( 881 ) — 7,051 Net income (loss) 124,810 8,095 132,905 ( 3,417 ) — 129,488 Capital expenditures (3) 397,292 7,014 404,306 1,368 — 405,674 Total Assets: As of December 31, 2022 $ 6,976,164 $ 264,322 $ 7,240,486 $ 187,027 $ ( 10,163 ) $ 7,417,350 As of December 31, 2021 6,458,244 265,422 6,723,666 132,158 ( 2,241 ) 6,853,583 As of December 31, 2020 6,035,340 268,971 6,304,311 109,658 ( 11,872 ) 6,402,097 (1) Intersegment eliminations reported as interest expense represent intercompany interest. Intersegment eliminations reported as assets represent intersegment accounts receivable. (2) Including interest expense to affiliated trusts. (3) The capital expenditures for the other businesses are included in other investing activities on the Consolidated Statements of Cash Flows.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Summary of Ratio of Depreciation to Average Depreciable Property and Average Service Lives for Utility Plan in Service (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Avista Utilities [Member]
Summary Of Significant Accounting Policies [Line Items]
Ratio of depreciation to average depreciable property	3.50%	3.54%	3.43%
Avista Utilities [Member] | Electric Thermal [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	26 years
Avista Utilities [Member] | Hydroelectric Production [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	79 years
Avista Utilities [Member] | Electric Transmission [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	50 years
Avista Utilities [Member] | Electric Distribution [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	39 years
Avista Utilities [Member] | Natural Gas Distribution [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	44 years
Avista Utilities [Member] | Other Plant in Service [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	8 years
Alaska Electric Light & Power [Member]
Summary Of Significant Accounting Policies [Line Items]
Ratio of depreciation to average depreciable property	2.78%	2.77%	2.77%
Alaska Electric Light & Power [Member] | Electric Thermal [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	41 years
Alaska Electric Light & Power [Member] | Hydroelectric Production [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	42 years
Alaska Electric Light & Power [Member] | Electric Transmission [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	43 years
Alaska Electric Light & Power [Member] | Electric Distribution [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	39 years
Alaska Electric Light & Power [Member] | Other Plant in Service [Member]
Summary Of Significant Accounting Policies [Line Items]
Average service lives for the utility plan in service	19 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Effective AFUDC Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Avista Utilities [Member]
Effective Rate On Allowance For Funds Used During Construction [Line Items]
Effective state AFUDC rate	7.12%	7.19%	7.25%
Alaska Electric Light & Power [Member]
Effective Rate On Allowance For Funds Used During Construction [Line Items]
Effective state AFUDC rate	8.08%	8.90%	8.04%

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Unrecognized tax benefits, income tax penalties and interest expense	$ 0	$ 0	$ 0
Government grants	$ 6,100,000
Restricted Stock [Member]
Summary Of Significant Accounting Policies [Line Items]
Award vesting period	3 years
Total Shareholder Return Market-Based Awards and Performance Awards [Member]
Summary Of Significant Accounting Policies [Line Items]
Award vesting period	3 years
Dividend component liability, current	$ 1,700,000	$ 1,500,000
Total Shareholder Return Market-Based Awards and Performance Awards [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Common stock issued range, percent of the performance shares granted	0%
Total Shareholder Return Market-Based Awards and Performance Awards [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Common stock issued range, percent of the performance shares granted	200%

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 7,567	$ 4,713	$ 5,846
Income tax benefits	1,589	990	1,228
Excess tax benefits (expenses) on settled share-based employee payments	$ 19	$ (909)	$ (165)
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the year	115,746	62,594	45,540
Shares vested during the year	44,829	34,854	56,203
Unvested shares at end of year	157,860	96,127	71,706
Unrecognized compensation expense at end of year (in thousands)	$ 3,923	$ 2,215	$ 2,003
Total Shareholder Return Market-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the year	69,814	64,910	47,848
Shares vested during the year	43,730	77,174	71,299
Shares earned based on market metrics	48,890	58,652
Unvested shares at end of year	130,567	107,854	122,133
Unrecognized compensation expense at end of year (in thousands)	$ 3,533	$ 2,653	$ 2,296
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the year	69,814	64,910	47,848
Shares vested during the year	43,730	38,590	35,622
Shares earned based on market metrics		26,627	63,763
Unvested shares at end of year	130,567	107,854	83,464
Unrecognized compensation expense at end of year (in thousands)	$ 2,471	$ 1,223	$ 1,090

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Other Expense (Income) - Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Interest income	$ (1,957)	$ (1,943)	$ (1,952)
Interest on regulatory deferrals	(1,914)	(1,206)	(1,222)
Equity-related AFUDC	(6,704)	(7,004)	(6,970)
Non-service portion of pension and other postretirement benefit expenses	(3,037)	1,386	6,433
Net (income) loss on investments	(48,492)	(21,402)	(905)
Other income	(613)	(3,129)	(201)
Total	$ (62,717)	$ (33,298)	$ (4,817)

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Allowance as of the beginning of the year		$ 10,465	$ 11,387	$ 2,419
Additions expensed during the year	[1]	149	9,279	11,280
Net deductions	[2]	(4,141)	(10,201)	(2,312)
Allowance as of the end of the year		$ 6,473	$ 10,465	$ 11,387
[1] Increases in 2021 and 2020 related to COVID-19 bad debt expense in excess of the amount recovered through rates. Increase in 2021 relates to COVID forgiveness program. The Company also received support from various government agencies in 2022 in the amount of $ 6.1 million, which was applied to overdue customer accounts.

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Estimated Retirement Costs Collected from Customers (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Regulated Asset Liability [Line Items]
Regulatory liability for utility plant retirement costs	$ 840,837	$ 861,515
Utility Plant Retirement Costs [Member]
Regulated Asset Liability [Line Items]
Regulatory liability for utility plant retirement costs	$ 376,817	$ 350,190

Summary of Significant Accou_11

Summary of Significant Accounting Policies - Summary of Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Balance as of December 31, 2020 and 2021	$ 52,426	$ 52,426
Alaska Electric Light & Power [Member]
Goodwill [Line Items]
Balance as of December 31, 2020 and 2021	52,426
Accumulated Impairment Losses [Member]
Goodwill [Line Items]
Balance as of December 31, 2020 and 2021	$ 0

Summary of Significant Accou_12

Summary of Significant Accounting Policies - Summary of Appropriated Retained Earnings Amount Included in Retained Earnings (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Appropriated Retained Earnings [Abstract]
Appropriated retained earnings	$ 57,231	$ 53,620

Balance Sheet Components - Mate

Balance Sheet Components - Materials and Supplies, Fuel Stock and Stored Natural Gas (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Materials and supplies	$ 75,766	$ 62,003
Stored natural gas	26,788	17,604
Fuel stock	5,120	5,126
Total	$ 107,674	$ 84,733

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Collateral posted for derivative instruments after netting with outstanding derivative liabilities	$ 66,142	$ 21,477
Prepayments	30,201	24,387
Income taxes receivable	30,740	29,615
Derivative assets net of collateral	18,198	1,442
Other	5,886	3,833
Total	$ 151,167	$ 80,754

Balance Sheet Components - Othe

Balance Sheet Components - Other Property and Investments-Net and Other Non-current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Equity investments	$ 147,809	$ 91,057
Operating lease ROU assets	$ 68,238	$ 70,133
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total	Total
Finance lease ROU assets	$ 40,056	$ 43,697
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total	Total
Non-utility property	$ 25,401	$ 20,033
Notes receivable	17,954	14,949
Long-term prepaid license fees	17,936	8,465
Pension assets	13,382
Investment in affiliated trust	11,547	11,547
Deferred compensation assets	7,541	9,513
Other	15,221	11,149
Total	$ 365,085	$ 280,543

Balance Sheet Components - Ot_2

Balance Sheet Components - Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Accrued taxes other than income taxes	$ 38,568	$ 41,706
Employee paid time off accruals	29,279	27,741
Accrued interest	20,863	17,538
Pensions and other postretirement benefits	15,625	13,582
Derivative liabilities	26,910	28,801
Deferred wholesale revenue	8,481	884
Other	49,689	38,609
Total	$ 189,415	$ 168,861

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Other Non-Current Liabilities and Deferred Credits (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Operating lease liabilities	$ 64,284	$ 66,068
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Total	Total
Finance lease liabilities	$ 42,495	$ 45,730
Deferred investment tax credits	28,784	29,313
Asset retirement obligations	15,783	17,142	$ 17,194	$ 20,338
Derivative liabilities	7,892	4,525
Other	16,617	15,347
Total	$ 175,855	$ 178,125

Revenue - Unbilled Accounts Rec

Revenue - Unbilled Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Unbilled accounts receivable	$ 81,691	$ 74,479

Revenue - Schedule of Utilities

Revenue - Schedule of Utilities Operating Revenue Expense Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Utility-related taxes	$ 69,931	$ 62,736	$ 59,319

Revenue - Additional Informatio

Revenue - Additional Information (Details) $ in Millions	Dec. 31, 2022 USD ($)
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 11.7

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 1,710,207	$ 1,438,936	$ 1,321,891
Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	434,490	413,657	396,403
Commercial and Governmental Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	364,438	352,034	327,726
Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	107,740	106,756	103,103
Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	7,737	7,722	7,555
Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	914,405	880,169	834,787
Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	32,307	21,005	18,236
Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	49,920	33,870	19,252
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	996,632	935,044	872,275
Avista Utilities [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,663,815	1,392,999	1,277,468
Avista Utilities [Member] | Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	414,823	394,717	377,785
Avista Utilities [Member] | Commercial and Governmental Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	338,656	326,173	303,972
Avista Utilities [Member] | Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	107,740	106,756	103,103
Avista Utilities [Member] | Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	7,483	7,472	7,303
Avista Utilities [Member] | Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	868,702	835,118	792,163
Avista Utilities [Member] | Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	32,307	21,005	18,236
Avista Utilities [Member] | Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	49,920	33,870	19,252
Avista Utilities [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	950,929	889,993	829,651
Avista Utilities [Member] | Residential Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	284,452	221,405	213,612
Avista Utilities [Member] | Commercial Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	139,923	100,819	94,937
Avista Utilities [Member] | Industrial and Interruptible Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	10,471	7,796	7,128
Avista Utilities [Member] | Retail Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	434,846	330,020	315,677
Avista Utilities [Member] | Transportation Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	8,627	8,547	7,917
Avista Utilities [Member] | Other Natural Gas Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	5,625	5,344	4,501
Avista Utilities [Member] | Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	449,098	343,911	328,095
Avista Utilities [Member] | Revenue from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues	1,400,027	1,233,904	1,157,746
Avista Utilities [Member] | Derivative revenues
Disaggregation of Revenue [Line Items]
Revenues	286,309	152,590	110,313
Avista Utilities [Member] | Alternative Revenue Programs [Member]
Disaggregation of Revenue [Line Items]
Revenues	(33,357)	(6,635)	(3,814)
Avista Utilities [Member] | Deferrals and Amortizations for Rate Refunds to Customers
Disaggregation of Revenue [Line Items]
Revenues	207	2,984	5,335
Avista Utilities [Member] | Other Utility Revenues
Disaggregation of Revenue [Line Items]
Revenues	10,629	10,156	7,888
Alaska Electric Light & Power [Member]
Disaggregation of Revenue [Line Items]
Revenues	45,704	45,366	42,809
Alaska Electric Light & Power [Member] | Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	19,667	18,940	18,618
Alaska Electric Light & Power [Member] | Commercial and Governmental Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	25,782	25,861	23,754
Alaska Electric Light & Power [Member] | Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	254	250	252
Alaska Electric Light & Power [Member] | Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	45,703	45,051	42,624
Alaska Electric Light & Power [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax	45,703	45,051	42,624
Alaska Electric Light & Power [Member] | Revenue from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues	45,703	45,051	42,624
Alaska Electric Light & Power [Member] | Deferrals and Amortizations for Rate Refunds to Customers
Disaggregation of Revenue [Line Items]
Revenues	(614)	(190)	(190)
Alaska Electric Light & Power [Member] | Other Utility Revenues
Disaggregation of Revenue [Line Items]
Revenues	615	505	375
Corporate and Other [Member]
Disaggregation of Revenue [Line Items]
Revenues	688	571	1,614
Corporate and Other [Member] | Revenue from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues		2	564
Corporate and Other [Member] | Other Revenues
Disaggregation of Revenue [Line Items]
Revenues	$ 688	$ 569	$ 1,050

Leases - Additional Information

Leases - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Operating lease, existence of option to extend	true
Minimum [Member]
Lessee, Lease, Description [Line Items]
Operating lease, remaining terms of contract	1 year
Operating lease, options to extend lease term	5 years
Maximum [Member]
Lessee, Lease, Description [Line Items]
Operating lease, remaining terms of contract	71 years
Operating lease, options to extend lease term	50 years
Snettisham Hydroelectric Project [Member]
Lessee, Lease, Description [Line Items]
Finance lease expiration year	2034
State of Montana [Member] | Hydroelectric Facilities in the Clark Fork River Basin [Member]
Lessee, Lease, Description [Line Items]
Operating lease expiration year	2046
ASC 842 [Member]
Lessee, Lease, Description [Line Items]
Change in accounting principle, accounting standards update, adopted	true

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Fixed lease cost (Other operating expenses)	$ 4,986	$ 4,970
Variable lease cost (Other operating expenses)	1,567	1,180
Amortization of ROU asset (Depreciation and amortization)	3,641	3,641
Interest on lease liabilities (Interest expense)	2,375	2,522
Operating Lease [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	6,553	6,150
Finance Lease [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 6,016	$ 6,163

Leases - Summary of Supplementa

Leases - Summary of Supplemental Cash Flow Information related to Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating cash outflows:
Operating lease payments	$ 4,828	$ 4,805
Interest on finance lease	2,375	2,522
Total operating cash outflows	7,203	7,327
Finance cash outflows:
Principal payments on finance lease	$ 3,085	$ 2,935

Leases - Summary of Supplemen_2

Leases - Summary of Supplemental Balance Sheet Information Related to Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease ROU assets	$ 68,238	$ 70,133
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other property and investments-net and other non-current assets	Other property and investments-net and other non-current assets
Operating Lease, Liability, Current	$ 4,349	$ 4,301
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent	$ 64,284	$ 66,068
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Operating Lease, Liability	$ 68,633	$ 70,369
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Liabilities	Liabilities
Finance lease ROU assets	$ 40,056	$ 43,697
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other property and investments-net and other non-current assets	Other property and investments-net and other non-current assets
Finance Lease, Liability, Current	$ 3,235	$ 3,085
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Current	Other Liabilities, Current
Finance Lease, Liability, Noncurrent	$ 42,495	$ 45,730
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Finance Lease, Liability	$ 45,730	$ 48,815
Operating leases, Weighted Average Remaining Lease Term	23 years 3 months 10 days	24 years 2 months 19 days
Finance leases, Weighted Average Remaining Lease Term	5 years 5 months 1 day	6 years 3 months 25 days
Operating leases, Weighted Average Discount Rate	4.28%	4.28%
Finance leases, Weighted Average Discount Rate	4.07%	4.35%

Leases - Summary of Maturities

Leases - Summary of Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating Leases, Liability, Payments, Due year one	$ 4,850	$ 4,820
Operating Leases, Liability, Payments, Due year two	4,880	4,875
Operating Leases, Liability, Payments, Due year three	4,877	4,849
Operating Leases, Liability, Payments, Due year four	4,884	4,882
Operating Leases, Liability, Payments, Due year five	4,869	4,867
Operating Leases, Thereafter	86,991	91,845
Operating Leases, Total lease payments	111,351	116,138
Operating Leases, Less: imputed interest	(42,718)	(45,769)
Operating Leases, Total	$ 68,633	$ 70,369
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Liabilities	Liabilities
Finance Leases, Liability, Payments, Due year one	$ 5,456	$ 5,460
Finance Leases, Liability, Payments, Due year two	5,458	5,459
Finance Leases, Liability, Payments, Due year three	5,459	5,456
Finance Leases, Liability, Payments, Due year four	5,454	5,454
Finance Leases, Liability, Payments, Due year five	5,456	5,456
Finance Leases, Thereafter	32,748	38,204
Finance Leases, Total lease payments	60,031	65,489
Finance Leases, Less: imputed interest	(14,301)	(16,674)
Finance Leases, Total	$ 45,730	$ 48,815

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) MW	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	$ 7,417,350	$ 6,853,583	$ 6,402,097
VIE Commitments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	79,800
Limited Partnerships and Similar Entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Remaining Investment Commitment Amount	25,600
Equity Investment [Member] | VIE Commitments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	70,200
Notes Receivable [Member] | VIE Commitments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	$ 9,600
Minimum [Member] | Limited Partnerships and Similar Entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Restrictions on Withdrawal of Member Capital Account	2025
Maximum [Member] | Limited Partnerships and Similar Entities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Restrictions on Withdrawal of Member Capital Account	2036
Variable Interest Entity, Not Primary Beneficiary [Member] | Limited Partnerships and Similar Entities [Member] | VIE Commitments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	$ 63,400
Lancaster Power Purchase Agreement [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Evaluated Power Capacity | MW	270
Variable Interest Entity, Reporting Entity Involvement, Contractual Commitment, Amount	$ 117,400
Lancaster Power Purchase Agreement [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Minimum [Member]
Variable Interest Entity [Line Items]
Average service lives for the utility plan in service	15 years
Lancaster Power Purchase Agreement [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Maximum [Member]
Variable Interest Entity [Line Items]
Average service lives for the utility plan in service	25 years

Equity Investments - Summary of

Equity Investments - Summary of Equity Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Equity Investments [Line items]
Equity method investments	$ 70,196	$ 66,896
Total	147,809	91,057
Non-recurring Fair Value [Member]
Equity Investments [Line items]
Investments without readily determinable fair value	23,329	$ 24,161
Recurring Fair Value [Member]
Equity Investments [Line items]
Investments without readily determinable fair value	$ 54,284

Equity Investments - Additional

Equity Investments - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) Investment
Equity Investments [Line items]
Gains on equity investments without readily determinable fair value, cumulative amount | $	$ 14.8
Recurring fair value [Member]
Equity Investments [Line items]
Number of recurring fair value equity investments | Investment	2

Equity Investments - Summary _2

Equity Investments - Summary of Net Unrealized Gains Related to Investments without Readily Determinable Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Equity Investments [Line items]
Total	$ 45,667	$ 8,761	$ 925
Recurring fair value [Member]
Equity Investments [Line items]
Unrealized gain	33,382
Non-recurring fair value [Member]
Equity Investments [Line items]
Unrealized gain	$ 12,285	$ 8,761	$ 925

Derivatives and Risk Manageme_3

Derivatives and Risk Management - Schedule of Energy Commodity Derivative Volumes (Details) MWh in Thousands, MMBTU in Thousands	12 Months Ended
	Dec. 31, 2022 MWh MMBTU	Dec. 31, 2021 MMBTU MWh
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
Year one | MWh	5	129
Year two | MWh	0	0
Year three | MWh	0	0
Year four | MWh		0
Purchase [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
Year one | MMBTU	19,140	7,114
Year two | MMBTU	533	378
Year three | MMBTU	450	228
Year four | MMBTU		0
Purchase [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
Year one | MWh	0
Year two | MWh	0	0
Year three | MWh	0	0
Year four | MWh		0
Purchase [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
Year one | MMBTU	79,253	61,405
Year two | MMBTU	30,658	23,218
Year three | MMBTU	4,895	3,413
Year four | MMBTU		0
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
Year one | MWh	136	234
Year two | MWh	0	0
Year three | MWh	0	0
Year four | MWh		0
Sales [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
Year one | MMBTU	4,145	3,933
Year two | MMBTU	1,370	1,360
Year three | MMBTU	1,115	1,370
Year four | MMBTU		1,115
Sales [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
Year one | MWh	1,011	452
Year two | MWh	0	0
Year three | MWh	0	0
Year four | MWh		0
Sales [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
Year one | MMBTU	29,473	31,485
Year two | MMBTU	9,668	9,323
Year three | MMBTU	1,125	228
Year four | MMBTU		0

Derivatives and Risk Manageme_4

Derivatives and Risk Management - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) MMBTU MWh	Dec. 31, 2021 USD ($) MWh MMBTU
Canadian [Member]
Derivative [Line Items]
Number of days Canadian currency prices are settled with U.S. dollars	60 days
Interest Rate Swap [Member]
Derivative [Line Items]
Letters of credit outstanding | $	$ 0	$ 0
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MWh	0	0
Purchase [Member] | Physical [Member] | Gas Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MMBTU	0	0
Purchase [Member] | Financial [Member] | Electric Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MWh	0	0
Purchase [Member] | Financial [Member] | Gas Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MMBTU	0	0
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MWh	0	0
Sales [Member] | Physical [Member] | Gas Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MMBTU	0	0
Sales [Member] | Financial [Member] | Electric Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MWh	0	0
Sales [Member] | Financial [Member] | Gas Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MMBTU	0	0

Derivatives and Risk Manageme_5

Derivatives and Risk Management - Summary of Foreign Currency Exchange Derivatives (Details) $ in Thousands, $ in Thousands	Dec. 31, 2022 USD ($) DerivativeContracts	Dec. 31, 2022 CAD ($) DerivativeContracts	Dec. 31, 2021 USD ($) DerivativeContracts	Dec. 31, 2021 CAD ($) DerivativeContracts
Foreign Currency Fair Value Hedge Derivative [Line Items]
Number of contracts | DerivativeContracts	19	19	25	25
United States of America, Dollars [Member] | Foreign Exchange Contract [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Notional amount	$ 8,563		$ 8,571
Canada, Dollars [Member] | Foreign Exchange Contract [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Notional amount		$ 11,659		$ 10,957

Derivatives and Risk Manageme_6

Derivatives and Risk Management - Summary of Unsettled Interest Rate Swap Derivatives (Details) - Interest Rate Swap [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) Contract	Dec. 31, 2021 USD ($) Contract
2022 [Member]
Derivatives, Fair Value [Line Items]
Number of Contracts | Contract		13
Notional Amount | $		$ 140,000
Mandatory Cash Settlement Date		2022
2023 [Member]
Derivatives, Fair Value [Line Items]
Number of Contracts | Contract	4	2
Notional Amount | $	$ 40,000	$ 20,000
Mandatory Cash Settlement Date	2023	2023
2024 [Member]
Derivatives, Fair Value [Line Items]
Number of Contracts | Contract	1	1
Notional Amount | $	$ 10,000	$ 10,000
Mandatory Cash Settlement Date	2024	2024

Derivatives and Risk Manageme_7

Derivatives and Risk Management - Schedules of Fair Values and Locations of Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Gross Asset	$ 157,704	$ 36,581
Gross Liability	(276,846)	(74,940)
Collateral Netting	105,439	9,089
Net Asset (Liability) on Balance Sheet	(13,703)	(29,270)
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Collateral Netting	105,439	9,089
Other Current Assets [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	43
Net Asset (Liability) on Balance Sheet	43
Other Current Assets [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	8,536
Net Asset (Liability) on Balance Sheet	8,536
Other Current Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	32,257	1,506
Gross Liability	(22,638)	(107)
Net Asset (Liability) on Balance Sheet	9,619	1,399
Other Property and Investments-Net and Other Non-current Assets [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	2,648	1,149
Net Asset (Liability) on Balance Sheet	2,648	1,149
Other Property and Investments-Net and Other Non-current Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	312	6,844
Gross Liability	(16)	(5,335)
Net Asset (Liability) on Balance Sheet	296	1,509
Other Current Liabilities [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Liability	(3)	(19)
Net Asset (Liability) on Balance Sheet	(3)	(19)
Other Current Liabilities [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset		1,170
Gross Liability	(52)	(25,196)
Net Asset (Liability) on Balance Sheet	(52)	(24,026)
Other Current Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	107,902	25,771
Gross Liability	(229,607)	(39,616)
Collateral Netting	94,850	9,089
Net Asset (Liability) on Balance Sheet	(26,855)	(4,756)
Other Noncurrent Liabilities [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Liability		(78)
Net Asset (Liability) on Balance Sheet		(78)
Other Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	6,049	141
Gross Liability	(24,530)	(4,589)
Collateral Netting	10,589
Net Asset (Liability) on Balance Sheet	$ (7,892)	$ (4,448)

Derivatives and Risk Manageme_8

Derivatives and Risk Management - Schedule of Collateral Outstanding Related to Derivative Instruments (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Balance sheet offsetting (cash collateral against net derivative positions)	$ 105,439,000	$ 9,089,000
Commodity Contracts [Member]
Derivative [Line Items]
Cash collateral posted	171,581,000	30,567,000
Letters of credit outstanding	49,425,000	34,000,000
Balance sheet offsetting (cash collateral against net derivative positions)	105,439,000	9,089,000
Interest Rate Swap [Member]
Derivative [Line Items]
Letters of credit outstanding	0	0
Liabilities with credit-risk-related contingent features	52,000	25,274,000
Additional collateral to post	$ 52,000	$ 25,274,000

Jointly Owned Electric Facili_3

Jointly Owned Electric Facilities - Additional Information (Details)	Dec. 31, 2022
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Owners percentage interest	15%

Jointly Owned Electric Facili_4

Jointly Owned Electric Facilities - Schedule of Utility Plant in Service for Colstrip And Accumulated Depreciation (Details) - Colstrip Generating Project [Member] - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Jointly Owned Utility Plant Interests [Line Items]
Utility plant in service	$ 390,852	$ 395,028
Accumulated depreciation	$ (315,223)	$ (302,220)

Property, Plant And Equipment -

Property, Plant And Equipment - Schedule of Net Utility Property (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Utility plant in service	$ 7,561,688	$ 7,166,580
Construction work in progress	164,147	205,405
Total	7,725,835	7,371,985
Less: Accumulated depreciation and amortization	2,281,126	2,146,470
Total net utility property	$ 5,444,709	$ 5,225,515

Property, Plant And Equipment_2

Property, Plant And Equipment - Schedule of Major Classifications of Property, Plant And Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Public Utility, Property, Plant and Equipment [Line Items]
Construction work-in-progress (CWIP) and other	$ 164,147	$ 205,405
Total	7,725,835	7,371,985
Other Property	365,085	280,543
Total	7,742,466	7,389,803
Avista Utilities [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Total	7,545,007	7,199,017
Common Plant	744,173	740,339
Avista Utilities [Member] | Electricity [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Production	1,593,795	1,494,371
Transmission	994,709	945,624
Distribution	2,236,376	2,093,937
Construction work-in-progress (CWIP) and other	376,981	424,733
Total	5,201,861	4,958,665
Avista Utilities [Member] | Natural Gas [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Distribution	1,452,637	1,356,477
Construction work-in-progress (CWIP) and other	88,264	87,852
Total	1,598,973	1,500,013
Natural gas underground storage	58,072	55,684
Alaska Electric Light & Power [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Total	180,828	172,968
Common Plant	10,018	9,726
Alaska Electric Light & Power [Member] | Electricity [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Production	106,390	106,094
Transmission	22,856	22,691
Distribution	29,269	27,138
Construction work-in-progress (CWIP) and other	12,295	7,319
Total	170,810	163,242
Corporate and Other [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Other Property	$ 16,631	$ 17,818

Property, Plant And Equipment_3

Property, Plant And Equipment - Schedule of Major Classifications of Property, Plant And Equipment (Parenthetical) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Corporate and Other [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 2.4	$ 2.3

Asset Retirement Obligations -

Asset Retirement Obligations - Schedule of Changes in Asset Retirement Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligation at beginning of year	$ 17,142	$ 17,194	$ 20,338
Liabilities incurred		825	(2,315)
Liabilities settled	(1,964)	(1,541)	(1,645)
Accretion expense	605	664	816
Asset retirement obligation at end of year	$ 15,783	$ 17,142	$ 17,194

Pension Plans and Other Postr_3

Pension Plans and Other Postretirement Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Payment for pension benefits		$ 42,000	$ 42,000	$ 22,000
Settlement loss		$ 11,800
Percentage of service related net periodic benefit costs capitalized to utility property		40%
Percentage of service related net periodic benefit costs recorded to operating expenses		60%
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] | Executive Officer [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation, earlier of retirement, termination, disability or death, percent		75%
Deferred compensation incentive payments, percent		100%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation		55%	55%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation		40%	40%
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation		5%	5%
Absolute Return [Member]
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation		0%	0%
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions to pension plan		$ 10,000
Settlement loss	[1]	11,828
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions to pension plan		$ 7,000
Other Postretirement Benefits [Member] | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation		60%	60%
Other Postretirement Benefits [Member] | Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation		40%	40%
[1] The settlement loss was deferred as a regulatory asset to be amortized over future periods.

Pension Plans and Other Postr_4

Pension Plans and Other Postretirement Benefit Plans - Schedule of Expected Benefit Payments (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Pension Plan And SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
2023	$ 41,993
2024	41,759
2025	42,207
2026	42,517
2027	43,037
Total 2028- 2032	226,781
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2023	7,031
2024	7,234
2025	7,436
2026	7,585
2027	7,771
Total 2028- 2032	$ 40,959

Pension Plans and Other Postr_5

Pension Plans and Other Postretirement Benefit Plans - Change in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities		$ (15,625)	$ (13,582)
Non-current liabilities		(93,901)	(153,467)
Accumulated other comprehensive loss for unfunded benefit obligation for pensions and other postretirement benefit plans		(2,058)	(11,039)
Pension Plan And SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation as of beginning of year		799,042	826,915
Service cost	[1]	23,877	25,306	$ 22,392
Interest cost		$ 26,536	$ 26,160	27,853
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]		Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses	Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses
Actuarial (gain)/loss		$ (204,775)	$ (13,997)
Plan change		3,302
Settlement		60,206
Benefits paid		(30,067)	(65,342)
Benefit obligation as of end of year		557,709	799,042	826,915
Fair value of plan assets as of beginning of year		750,963	722,024
Actual return on plan assets		(163,866)	50,370
Employer contributions		42,000	42,000
Settlement		(60,206)
Benefits paid		(28,188)	(63,431)
Fair value of plan assets as of end of year		540,703	750,963	722,024
Funded status		(17,006)	(48,079)
Other non-current assets		13,382
Other current liabilities		(1,934)	(1,951)
Non-current liabilities		(28,454)	(46,128)
Net amount recognized		(17,006)	(48,079)
Accumulated pension benefit obligation		495,654	685,493
Unrecognized prior service cost (credit)		4,105	1,699
Unrecognized net actuarial loss		83,794	94,109
Total		87,899	95,808
Less regulatory asset		(85,198)	(85,550)
Accumulated other comprehensive loss for unfunded benefit obligation for pensions and other postretirement benefit plans		$ 2,701	$ 10,258
Discount rate for benefit obligation		6.10%	3.39%
Discount rate for annual expense		3.39%	3.25%
Expected long-term return on plan assets		5.80%	5.40%
Rate of compensation increase		4.69%	4.66%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation as of beginning of year		$ 167,598	$ 161,233
Service cost	[1]	4,369	4,114	3,902
Interest cost		$ 5,503	5,139	6,042
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]		Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses
Actuarial (gain)/loss		$ (54,120)	2,808
Benefits paid		(7,715)	(5,696)
Benefit obligation as of end of year		115,635	167,598	161,233
Fair value of plan assets as of beginning of year		59,544	52,173
Actual return on plan assets		(10,072)	7,371
Fair value of plan assets as of end of year		49,472	59,544	$ 52,173
Funded status		(66,163)	(108,054)
Other current liabilities		(706)	(684)
Non-current liabilities		(65,457)	(107,370)
Net amount recognized		(66,163)	(108,054)
Unrecognized prior service cost (credit)		(1,911)	(2,741)
Unrecognized net actuarial loss		13,643	48,872
Total		11,732	46,131
Less regulatory asset		(12,375)	(45,350)
Accumulated other comprehensive loss for unfunded benefit obligation for pensions and other postretirement benefit plans		$ (643)	$ 781
Discount rate for benefit obligation		6.10%	3.40%
Discount rate for annual expense		3.40%	3.27%
Expected long-term return on plan assets		4.70%	4.60%
Other Postretirement Benefits [Member] | Pre-Age 65 [Member]
Defined Benefit Plan Disclosure [Line Items]
Medical cost trend – initial		6.25%	6%
Medical cost trend – ultimate		5%	5%
Ultimate medical cost trend year		2028	2026
Other Postretirement Benefits [Member] | Post-Age 65 [Member]
Defined Benefit Plan Disclosure [Line Items]
Medical cost trend – initial		6.25%	6%
Medical cost trend – ultimate		5%	5%
Ultimate medical cost trend year		2028	2026
Other Postretirement Benefits [Member] | Retirees [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation as of beginning of year		$ 78,347
Benefit obligation as of end of year		61,984	$ 78,347
Other Postretirement Benefits [Member] | Fully eligible employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation as of beginning of year		32,144
Benefit obligation as of end of year		19,731	32,144
Other Postretirement Benefits [Member] | Other participants [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation as of beginning of year		57,107
Benefit obligation as of end of year		$ 33,920	$ 57,107
[1] Total service costs in the table above are recorded to the same accounts as labor expense. Labor and benefits expense is recorded to various projects based on whether the work is a capital project or an operating expense. Approximately 40 percent of all labor and benefits is capitalized to utility property and 60 percent is expensed to utility other operating expenses.

Pension Plans and Other Postr_6

Pension Plans and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Settlement loss		$ 11,800
Pension Plan And SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	23,877	$ 25,306	$ 22,392
Interest cost		26,536	26,160	27,853
Expected return on plan assets		$ (43,872)	$ (39,088)	$ (34,886)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax
Amortization of prior service cost		$ 257	$ 257	$ 257
Net loss recognition		4,180	6,645	6,717
Settlement loss	[2]	11,828
Net periodic benefit cost		22,806	19,280	22,333
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	[1]	4,369	4,114	3,902
Interest cost		5,503	5,139	6,042
Expected return on plan assets		$ (2,799)	$ (2,400)	$ (2,377)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax
Amortization of prior service cost		$ (1,050)	$ (921)	$ (958)
Net loss recognition		3,344	3,865	4,871
Net periodic benefit cost		$ 9,367	$ 9,797	$ 11,480
[1] Total service costs in the table above are recorded to the same accounts as labor expense. Labor and benefits expense is recorded to various projects based on whether the work is a capital project or an operating expense. Approximately 40 percent of all labor and benefits is capitalized to utility property and 60 percent is expensed to utility other operating expenses. The settlement loss was deferred as a regulatory asset to be amortized over future periods.

Pension Plans and Other Postr_7

Pension Plans and Other Postretirement Benefit Plans - Investment Allocation Percentages By Asset Classes (Details)	Dec. 31, 2022	Dec. 31, 2021
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation	55%	55%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation	40%	40%
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation	5%	5%
Absolute Return [Member]
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation	0%	0%

Pension Plans and Other Postr_8

Pension Plans and Other Postretirement Benefit Plans - Schedule of Fair Value Hierarchy of pension Plan's Assets (Details) - Pension Plan And SERP [Member] - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 540,703	$ 750,963	$ 722,024
Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,110	6,259
Fixed Income Securities [Member] | US Government Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,732	19,310
Fixed Income Securities [Member] | Domestic Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	161,180	233,496
Fixed Income Securities [Member] | Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23,108	34,270
Fixed Income Securities [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,427	18,558
Mutual Funds [Member] | U.S Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	154,442	236,552
Mutual Funds [Member] | International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	58,933	112,873
Common/Collective Trusts [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30,406	31,040
Partnership And Closely Held Investments [Member] | International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	69,792	50,427
Partnership And Closely Held Investments [Member] | Absolute Return [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		363
Partnership And Closely Held Investments [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,573	7,815
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	213,375	349,425
Level 1 [Member] | Mutual Funds [Member] | U.S Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	154,442	236,552
Level 1 [Member] | Mutual Funds [Member] | International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	58,933	112,873
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	219,557	311,893
Level 2 [Member] | Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,110	6,259
Level 2 [Member] | Fixed Income Securities [Member] | US Government Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16,732	19,310
Level 2 [Member] | Fixed Income Securities [Member] | Domestic Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	161,180	233,496
Level 2 [Member] | Fixed Income Securities [Member] | Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23,108	34,270
Level 2 [Member] | Fixed Income Securities [Member] | Municipal Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 13,427	$ 18,558

Pension Plans and Other Postr_9

Pension Plans and Other Postretirement Benefit Plans - Schedule of Fair Value Hierarchy of Other Postretirement Plan Assets (Details) - Other Postretirement Benefits [Member] - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 49,472	$ 59,544	$ 52,173
Mutual Fund [Member] | Balanced Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	49,472	59,545
Level 1 [Member] | Mutual Fund [Member] | Balanced Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	$ 49,472	$ 59,545
[1] The balanced index fund for 2022 and 2021 is a single mutual fund that includes a percentage of U.S. equity and fixed income securities and International equity and fixed income securities.

Pension Plans and Other Post_10

Pension Plans and Other Postretirement Benefit Plans - Employer Matching Contributions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits, Description [Abstract]
Employer 401(k) matching contributions	$ 13,258	$ 11,671	$ 11,742

Pension Plans and Other Post_11

Pension Plans and Other Postretirement Benefit Plans - Deferred Compensation Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member]
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Deferred compensation assets and liabilities	$ 7,541	$ 9,513

Accounting For Income Taxes - S

Accounting For Income Taxes - Schedule of Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Current income tax expense (benefit)	$ 1,040	$ 807	$ (37,913)
Deferred income tax expense (benefit)	(18,231)	11,224	44,964
Total income tax expense (benefit)	$ (17,191)	$ 12,031	$ 7,051

Accounting For Income Taxes - A

Accounting For Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017
Components of Income Tax Expense (Benefit) [Line Items]
Federal statutory tax rate	21%	21%	21%	21%	35%
State Tax Credit Carryforward [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Tax credit carryforward, amount	$ 13.6
Tax credit carryforwards, net of valuation allowance	9.7
Tax credit carryforward, valuation allowance	$ (3.9)
Minimum [Member] | State Tax Credit Carryforward [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Tax credit carryforward, expiration date	2023
Maximum [Member] | State Tax Credit Carryforward [Member]
Components of Income Tax Expense (Benefit) [Line Items]
Tax credit carryforward, expiration date	2036

Accounting For Income Taxes -_2

Accounting For Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal income taxes at statutory rates	$ 28,977	$ 33,467	$ 28,673
Tax effect of regulatory treatment of utility plant differences	(12,366)	(13,820)	(12,893)
State income tax expense	1,676	1,385	814
Flow through related to deduction of meters and mixed service costs	(34,454)	(8,678)
Non-plant excess deferred turnaround			(8,476)
Customer refunds related to prior years at 35 percent			(1,189)
Other	(1,024)	(323)	122
Total income tax expense (benefit)	$ 17,191	$ (12,031)	$ (7,051)
Federal statutory tax rate	21%	21%	21%	21%	35%
Tax effect of regulatory treatment of utility plant differences	(9.00%)	(8.70%)	(9.40%)
State income tax expense	1.20%	0.80%	0.60%
Flow through related to deduction of meters and mixed service costs	(25.00%)	(5.40%)
Non-plant excess deferred turnaround			(6.20%)
Customer refunds related to prior years at 35 percent			(0.90%)
Other	(0.70%)	(0.20%)	0.10%
Effective Income Tax Rate Reconciliation, Percent	(12.50%)	7.50%	5.20%

Accounting For Income Taxes -_3

Accounting For Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017
Regulatory Liability [Line Items]
Federal statutory tax rate	21%	21%	21%	21%	35%
Regulatory liability, current	$ 95,665	$ 77,149
Effective income tax rate reconciliation, excess deferred income tax reversal amount			$ 8,476
Washington Utilities and Transportation Commission [Member]
Regulatory Liability [Line Items]
Effective income tax rate reconciliation, excess deferred income tax reversal amount			8,400
Washington Utilities and Transportation Commission [Member] | Income Tax Related [Member]
Regulatory Liability [Line Items]
Regulatory liability, current			$ 10,900

Accounting For Income Taxes -_4

Accounting For Income Taxes - Schedule of Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred income tax assets:
Regulatory liabilities	$ 197,998	$ 200,513
Tax credits and NOL carryforwards	74,782	64,994
Provisions for pensions	20,132	25,650
Other	54,903	38,181
Total gross deferred income tax assets	347,815	329,338
Valuation allowances for deferred tax assets	(3,874)	(9,626)
Total deferred income tax assets after valuation allowances	343,941	319,712
Deferred income tax liabilities:
Utility property, plant, and equipment	712,470	688,856
Regulatory assets	281,483	264,978
Other	24,983	8,587
Total deferred income tax liabilities	1,018,936	962,421
Net long-term deferred income tax liability	$ 674,995	$ 642,709

Energy Purchase Contracts Addit

Energy Purchase Contracts Additional Information (Details)	12 Months Ended
	Dec. 31, 2022
Minimum [Member]
Energy Purchase Contracts [Line Items]
Remaining term of purchase contract	1 month
Maximum [Member]
Energy Purchase Contracts [Line Items]
Remaining term of purchase contract	25 years

Energy Purchase Contracts (Sche

Energy Purchase Contracts (Schedule Of Utility Total Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Energy Purchase Contracts [Abstract]
Utility power resources	$ 660,967	$ 431,199	$ 324,297

Energy Purchase Contracts (Futu

Energy Purchase Contracts (Future Contractual Commitments For Power Resources And Natural Gas Resources) (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Energy Purchase Contracts [Line Items]
2023	$ 376,090
2024	294,410
2025	279,406
2026	242,793
2027	224,181
Thereafter	2,654,332
Total	4,071,212
Power Resources [Member]
Energy Purchase Contracts [Line Items]
2023	245,169
2024	215,044
2025	240,214
2026	214,747
2027	185,590
Thereafter	2,333,955
Total	3,434,719
Natural Gas Resources [Member]
Energy Purchase Contracts [Line Items]
2023	130,921
2024	79,366
2025	39,192
2026	28,046
2027	38,591
Thereafter	320,377
Total	636,493
Generation Transmission And Distribution Facilities [Member]
Energy Purchase Contracts [Line Items]
2023	30,562
2024	31,416
2025	32,255
2026	16,937
2027	17,343
Thereafter	178,193
Total	$ 306,706

Energy Purchase Contracts (PUD

Energy Purchase Contracts (PUD Contracts Expenses) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
P U D Contracts Expenses [Abstract]
Long-term contract for purchase of electric power, amount of long-term debt or lease obligation outstanding	$ 281

Short-Term Borrowings - Additio

Short-Term Borrowings - Additional Information (Details) - USD ($)	1 Months Ended			12 Months Ended
	Dec. 31, 2022	Nov. 30, 2022	Jun. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Apr. 30, 2014
Short-term Debt [Line Items]
Line of credit, outstanding	$ 0			$ 0
Current borrowings	100,000,000			100,000,000
Revolving credit agreement [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	100,000,000	$ 50,000,000		$ 100,000,000
Line of credit facility, expiration date		2023-11
Line of credit, additional borrowing	$ 50,000,000
Avista Utilities [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity						$ 400,000,000
Line of credit facility, expiration date			2026-06
Line of credit facility additional expiration period					1 year
Line of credit facility, covenant terms, maximum debt to equity ratio	65%			65%
Credit agreement amount borrowed	$ 150,000,000			$ 150,000,000
Letters of credit outstanding	35,563,000			35,563,000	$ 34,000,000
Avista Utilities [Member] | 2022 Term Loan [Member]
Short-term Debt [Line Items]
Principal amount	100,000,000			$ 100,000,000
Maturity date				Mar. 30, 2023
Additional principal amount	50,000,000			$ 50,000,000
Avista Utilities [Member] | Letter of Credit [Member]
Short-term Debt [Line Items]
Principal amount	50,000,000			50,000,000
Letters of credit outstanding	18,500,000			18,500,000
Alaska Electric Light & Power [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity	$ 25,000,000			$ 25,000,000
Line of credit facility, expiration date				2024-11
Line of credit facility, covenant terms, maximum debt to equity ratio	67.50%			67.50%
Line of credit, outstanding	$ 0			$ 0
Maximum [Member] | Avista Utilities [Member] | 2022 Term Loan [Member]
Short-term Debt [Line Items]
Principal amount	$ 150,000,000			$ 150,000,000

Short-Term Borrowings - Schedul

Short-Term Borrowings - Schedule of Balances Outstanding and Interest Rates of Borrowings (Details) - Avista Utilities [Member] - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Short-term Debt [Line Items]
Balance outstanding at end of period	$ 313,000	$ 284,000
Letters of credit outstanding at end of period	$ 35,563	$ 34,000
Average interest rate at end of period	5.31%	1.11%

Credit Agreements - Additional

Credit Agreements - Additional Information (Details) - Avista Utilities [Member] - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Short-term Debt [Line Items]
Credit agreement amount borrowed	$ 150,000
Letters of credit outstanding	$ 35,563	$ 34,000
Line of credit facility, covenant terms, maximum debt to equity ratio	65%

Long-Term Debt - Schedule Of Lo

Long-Term Debt - Schedule Of Long-Term Debt Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Secured Debt	$ 2,382,200	$ 2,232,200
Secured and Unsecured Debt	2,397,200	2,247,200
Unamortized debt discount	(726)	(632)
Unamortized Debt Issuance Expense	(18,261)	(14,498)
Total	2,378,213	2,232,070
Current portion of long-term debt	(13,500)	(250,000)
Long-term debt	$ 2,281,013	1,898,370
First Mortgage [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8%
Secured Debt [Member]
Debt Instrument [Line Items]
Pollution Control Bonds	$ (83,700)	(83,700)
2032 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Pollution Control Bonds	66,700
2034 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Pollution Control Bonds	17,000
Avista Utilities [Member]
Debt Instrument [Line Items]
Secured Debt	$ 2,307,200	2,157,200
Avista Utilities [Member] | 2022 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2022
Debt Instrument, Interest Rate, Stated Percentage	5.13%
Secured Debt	$ 0	250,000
Avista Utilities [Member] | 2023 7.18% - 7.54% [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year	2023
Medium-Term Notes, Noncurrent	$ 13,500	13,500
Avista Utilities [Member] | 2023 7.18% - 7.54% [Member] | Minimum [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.18%
Avista Utilities [Member] | 2023 7.18% - 7.54% [Member] | Maximum [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.54%
Avista Utilities [Member] | 2028 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year	2028
Debt Instrument, Interest Rate, Stated Percentage	6.37%
Medium-Term Notes, Noncurrent	$ 25,000	25,000
Avista Utilities [Member] | 2032 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year	2032
Pollution Control Bonds	$ 66,700	66,700
Avista Utilities [Member] | 2034 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year	2034
Pollution Control Bonds	$ 17,000	17,000
Avista Utilities [Member] | 2035 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2035
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Secured Debt	$ 150,000	150,000
Avista Utilities [Member] | 2037 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2037
Debt Instrument, Interest Rate, Stated Percentage	5.70%
Secured Debt	$ 150,000	150,000
Avista Utilities [Member] | 2040 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2040
Debt Instrument, Interest Rate, Stated Percentage	5.55%
Secured Debt	$ 35,000	35,000
Avista Utilities [Member] | 2041 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2041
Debt Instrument, Interest Rate, Stated Percentage	4.45%
Secured Debt	$ 85,000	85,000
Avista Utilities [Member] | 2044 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2044
Debt Instrument, Interest Rate, Stated Percentage	4.11%
Secured Debt	$ 60,000	60,000
Avista Utilities [Member] | 2045 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2045
Debt Instrument, Interest Rate, Stated Percentage	4.37%
Secured Debt	$ 100,000	100,000
Avista Utilities [Member] | 2047 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2047
Debt Instrument, Interest Rate, Stated Percentage	4.23%
Secured Debt	$ 80,000	80,000
Avista Utilities [Member] | 2047 3.91% [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2047
Debt Instrument, Interest Rate, Stated Percentage	3.91%
Secured Debt	$ 90,000	90,000
Avista Utilities [Member] | 2048 4.35% [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2048
Debt Instrument, Interest Rate, Stated Percentage	4.35%
Secured Debt	$ 375,000	375,000
Avista Utilities [Member] | 2049 3.43% [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2049
Debt Instrument, Interest Rate, Stated Percentage	3.43%
Secured Debt	$ 180,000	180,000
Avista Utilities [Member] | 2050 3.07% [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2050
Debt Instrument, Interest Rate, Stated Percentage	3.07%
Secured Debt	$ 165,000	165,000
Avista Utilities [Member] | 2051 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2051
Debt Instrument, Interest Rate, Stated Percentage	3.54%
Secured Debt	$ 175,000	175,000
Avista Utilities [Member] | 2.90% Due in 2051 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2051
Debt Instrument, Interest Rate, Stated Percentage	2.90%
Secured Debt	$ 140,000	140,000
Avista Utilities [Member] | 2052 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2052
Debt Instrument, Interest Rate, Stated Percentage	4%
Secured Debt	$ 400,000
Alaska Electric Light & Power [Member] | 2044 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Maturity Year	2044
Debt Instrument, Interest Rate, Stated Percentage	4.54%
Secured Debt	$ 75,000	75,000
Alaska Energy Resources Company [Member] | 2024 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Maturity Year	2024
Debt Instrument, Interest Rate, Stated Percentage	3.44%
Unsecured Debt	$ 15,000	$ 15,000

Long-Term Debt - Schedule Of _2

Long-Term Debt - Schedule Of Long-Term Debt Instruments (Parenthetical) (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2022 USD ($) Contract	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt		$ 399,856	$ 140,000	$ 165,000
Repayment of long-term debt	$ 250,000
Line of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	400,000
First Mortgage [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		8%
2032 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Pollution Control Bonds		$ 66,700
2034 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Pollution Control Bonds		$ 17,000
4.00% Due in 2052 [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Proceeds from issuance of long-term debt	$ 400,000
Debt Instrument, Interest Rate, Stated Percentage	4%
Maturity Year	2052
4.00% Due in 2052 [Member] | First Mortgage [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Number of interest rate swaps settled | Contract	13
Notional Amount	$ 140,000
Net payments from settlement of derivatives	$ 17,000

Long-Term Debt - Schedule Of _3

Long-Term Debt - Schedule Of Long-Term Debt Maturities (Details) - Future Long Term Debt Maturities Including Long Term Debt To Affiliated Trusts [Member] $ in Thousands	Dec. 31, 2022 USD ($)
Debt Instrument [Line Items]
2023	$ 13,500
2024	15,000
Thereafter	2,336,547
Total	$ 2,365,047

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended
	Mar. 31, 2022	Dec. 31, 2022
Debt Instrument [Line Items]
Repayment of long-term debt	$ 250
First Mortgage [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		8%
Avista Utilities [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Amount of First Mortgage Bonds that Could be Issued, Percent		66.66%
Amount of First Mortgage Bonds that Could be Issued		$ 1,400
Alaska Electric Light & Power [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Amount of First Mortgage Bonds that Could be Issued, Percent		66.66%
Amount of First Mortgage Bonds that Could be Issued		$ 40.4

Long-Term Debt to Affiliated _3

Long-Term Debt to Affiliated Trusts - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2023	Dec. 31, 2022	Dec. 31, 2000
Debt Instrument [Line Items]
Payments for repurchase of trust preferred securities			$ 10
Avista Corp [Member]
Debt Instrument [Line Items]
Noncontrolling interest, ownership percentage by parent		100%
1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member] | Avista Capital II [Member]
Debt Instrument [Line Items]
Junior subordinated debenture issuance date		1997
Principal amount		$ 51.5
Trust Preferred Securities Subject to Mandatory Redemption [Member] | 1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member] | Avista Capital II [Member]
Debt Instrument [Line Items]
Principal amount		$ 50
Debt instrument, description of variable rate basis		LIBOR
Debt instrument, basis spread on variable rate		0.875%
Trust Preferred Securities Subject to Mandatory Redemption [Member] | 1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member] | Three-month CME Term SOFR [Member] | Forecast [Member] | Avista Capital II [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.13661%
Debt instrument basis tenor spread adjustment rate	0.26161%
Common Trust Securities [Member] | 1997 Floating Rate Junior Subordinated Deferrable Interest Debentures, Series B [Member] | Avista Capital II [Member]
Debt Instrument [Line Items]
Principal amount		$ 1.5

Long-Term Debt to Affiliated _4

Long-Term Debt to Affiliated Trusts - Schedule of Distribution Rates Paid (Details) - Trust Preferred Securities Subject to Mandatory Redemption [Member]	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Interest rate	5.64%	1.05%	1.10%
Minimum [Member]
Debt Instrument [Line Items]
Interest rate	1.05%	0.99%	1.10%
Maximum [Member]
Debt Instrument [Line Items]
Interest rate	5.64%	1.10%	2.79%

Fair Value - Schedule of Carryi

Fair Value - Schedule of Carrying Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Finance Lease Obligation	$ 45,730	$ 48,815
Level 2 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	1,113,500	963,500
Level 2 [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	966,881	1,157,651
Level 3 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	1,200,000	1,200,000
Level 3 [Member] | Reported Value Measurement [Member] | Alaska Electric Light & Power [Member] | Finance Lease [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Finance Lease Obligation	45,730	48,815
Level 3 [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	881,480	1,366,619
Level 3 [Member] | Estimate of Fair Value Measurement [Member] | Alaska Electric Light & Power [Member] | Finance Lease [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Finance Lease Obligation	41,700	54,000
Affiliated Entity [Member] | Level 3 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	51,547	51,547
Affiliated Entity [Member] | Level 3 [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 42,836	$ 43,299

Fair Value - Additional Informa

Fair Value - Additional Information (Details)	Dec. 31, 2022 Investment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Number of equity investments measured at fair value on recurring basic	2
Measurement Input, Quoted Price [Member] | Secured and Unsecured Debt [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, measurement input	100
Measurement Input, Quoted Price [Member] | Minimum [Member] | Secured and Unsecured Debt [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, measurement input	60.16
Measurement Input, Quoted Price [Member] | Maximum [Member] | Secured and Unsecured Debt [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, measurement input	103.85

Fair Value - Schedule of Fair V

Fair Value - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset		$ 157,704	$ 36,581
Liability		276,846	74,940
Recurring fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure		82,825	13,460
Financial Liabilities Fair Value Disclosure		34,802	33,327
Counterparty and Cash Collateral Netting, Assets	[1]	(136,605)	(32,524)
Counterparty and Cash Collateral Netting, Liabilities	[1]	(242,044)	(41,613)
Recurring fair value [Member] | Fixed Income Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	[2]	1,267	1,809
Recurring fair value [Member] | Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity investments	[2]	54,284
Deferred compensation assets:	[2]	6,132	7,594
Recurring fair value [Member] | Energy commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and Cash Collateral Netting, Assets	[1],[3]	136,605	(31,354)
Derivative Asset	[3]	9,915	2,908
Counterparty and Cash Collateral Netting, Liabilities	[1],[3]	(242,044)	(40,443)
Derivative Liability	[3]	34,747	9,204
Recurring fair value [Member] | Natural Gas Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Liability		17,734
Recurring fair value [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and Cash Collateral Netting, Assets	[1]		(1,170)
Derivative Asset		11,184	1,149
Counterparty and Cash Collateral Netting, Liabilities	[1]		(1,170)
Derivative Liability		52	$ 24,104
Recurring fair value [Member] | Foreign Exchange Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset		$ 43
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Investments and Other Noncurrent Assets	Investments and Other Noncurrent Assets
Derivative Liability		$ 3	$ 19
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Recurring fair value [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure		$ 7,399	$ 9,403
Recurring fair value [Member] | Level 1 [Member] | Fixed Income Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	[2]	1,267	1,809
Recurring fair value [Member] | Level 1 [Member] | Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	[2]	6,132	7,594
Recurring fair value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure		157,459	36,438
Financial Liabilities Fair Value Disclosure		258,824	67,026
Recurring fair value [Member] | Level 2 [Member] | Energy commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	[3]	146,232	34,119
Liability	[3]	258,769	41,733
Recurring fair value [Member] | Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset		11,184	2,319
Liability		52	25,274
Recurring fair value [Member] | Level 2 [Member] | Foreign Exchange Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset		43	19
Liability		3
Recurring fair value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure		54,572	143
Financial Liabilities Fair Value Disclosure		18,022	7,914
Recurring fair value [Member] | Level 3 [Member] | Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity investments	[2]	54,284
Recurring fair value [Member] | Level 3 [Member] | Energy commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	[3]	288	143
Liability	[3]	$ 18,022	$ 7,914
[1] The Company is permitted to net derivative assets and derivative liabilities with the same counterparty when a legally enforceable master netting agreement exists. In addition, the Company nets derivative assets and derivative liabilities against any payables and receivables for cash collateral held or placed with these same counterparties. These assets are included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets. The level 3 energy commodity derivative balances are associated with natural gas exchange agreements

Fair Value - Schedule of Quanti

Fair Value - Schedule of Quantitative Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) MMBTU $ / MMBTU
Equity Investments [Member] | Recurring fair value [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments	$ 54,284	[1]
Equity Investments [Member] | Recurring fair value [Member] | Market Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, time to liquidity event	2 years
Equity Investments [Member] | Recurring fair value [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, terminal date	2024
Equity Investments [Member] | Recurring fair value [Member] | Discount Rate [Member] | Market Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, measurement input	30
Equity Investments [Member] | Recurring fair value [Member] | Discount Rate [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, measurement input	25
Equity Investments [Member] | Recurring fair value [Member] | Minimum [Member] | Market Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, comparable enterprise values	$ 130,000
Equity Investments [Member] | Recurring fair value [Member] | Minimum [Member] | Revenue Market Multiples [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, measurement input	1.44
Equity investments, revenue market multiples	$ 4,000
Equity Investments [Member] | Recurring fair value [Member] | Minimum [Member] | Market Multiple Reduction [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, measurement input	30
Equity Investments [Member] | Recurring fair value [Member] | Maximum [Member] | Market Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, comparable enterprise values	$ 388,600
Equity Investments [Member] | Recurring fair value [Member] | Maximum [Member] | Revenue Market Multiples [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, measurement input	6.55
Equity investments, revenue market multiples	$ 337,000
Equity Investments [Member] | Recurring fair value [Member] | Maximum [Member] | Market Multiple Reduction [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, measurement input	50
Equity Investments [Member] | Recurring fair value [Member] | Weighted Average [Member] | Market Approach [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, comparable enterprise values	$ 246,000
Equity Investments [Member] | Recurring fair value [Member] | Weighted Average [Member] | Revenue Market Multiples [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, measurement input	2.88
Equity Investments [Member] | Recurring fair value [Member] | Weighted Average [Member] | Market Multiple Reduction [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments, measurement input	40
Natural Gas Exchange Agreements [Member] | Purchase [Member] | Minimum [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative, Forward Price | $ / MMBTU	2.89
Transaction/Delivery Volumes | MMBTU	140,000
Natural Gas Exchange Agreements [Member] | Purchase [Member] | Maximum [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative, Forward Price | $ / MMBTU	4.19
Transaction/Delivery Volumes | MMBTU	370,000
Natural Gas Exchange Agreements [Member] | Purchase [Member] | Weighted Average [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative, Forward Price | $ / MMBTU	3.47
Natural Gas Exchange Agreements [Member] | Sales [Member] | Minimum [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative, Forward Price | $ / MMBTU	3.11
Transaction/Delivery Volumes | MMBTU	75,000
Natural Gas Exchange Agreements [Member] | Sales [Member] | Maximum [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative, Forward Price | $ / MMBTU	23.47
Transaction/Delivery Volumes | MMBTU	310,000
Natural Gas Exchange Agreements [Member] | Sales [Member] | Weighted Average [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative, Forward Price | $ / MMBTU	8.88
Natural Gas Exchange Agreements [Member] | Recurring fair value [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative Liability	$ (17,734)
Level 3 [Member] | Equity Investments [Member] | Recurring fair value [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Equity investments	$ 54,284	[1]
[1] These assets are included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets.

Fair Value - Schedule of Activi

Fair Value - Schedule of Activity For Energy Commodity and Equity Investments Derivative Assets (Liabilities) Measured At Fair Value Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)
Level 3 [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ (7,771)	$ (8,410)	$ (2,976)
Transfer in	20,902
Included in regulatory assets	(4,740)	4,292	(4,311)
Recognized in net income	33,382
Settlements	(5,223)	(3,653)	(1,123)
Ending Balance	36,550	(7,771)	(8,410)
Natural Gas Exchange Agreements [Member] | Level 3 [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	(7,771)	(8,410)	(2,976)
Included in regulatory assets	(4,740)	4,292	(4,311)
Settlements	(5,223)	(3,653)	(1,123)
Ending Balance	(17,734)	$ (7,771)	$ (8,410)
Equity Investment [Member] | Level 3 [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Transfer in	20,902
Recognized in net income	33,382
Ending Balance	$ 54,284

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Preferred stock, shares outstanding	0	0
Amount available for dividend distribution without affecting covenants	$ 258,600
Preferred stock, shares authorized	10,000,000
Proceeds from issuance of common stock	$ 137,778	$ 89,998	$ 72,200
Common stock, shares authorized	200,000,000	200,000,000
Common Stock [Member]
Class Of Stock [Line Items]
Shares issued through sales agency agreements	3,310,488	2,150,336	1,905,000
Issuance of common stock through sales agency agreements, net of issuance costs	$ 137,173	$ 88,457	$ 70,561
Sales Agency Agreement [Member]
Class Of Stock [Line Items]
Common stock, shares authorized	5,600,000
Common stock shares authorized under sales agency agreements remaining shares authorized to sell	2,300,000
Avista Utilities [Member]
Class Of Stock [Line Items]
Regulatory restrictions, maximum debt to equity	35%

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Loss [Abstract]
Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $547 and $2,934, respectively	$ 2,058	$ 11,039

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss, Net of Tax (Parenthetical) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Loss [Abstract]
Accumulated other comprehensive income (loss), pension and other postretirement benefit plans net unamortized (gain) loss, tax	$ 547	$ 2,934

Accumulated Other Comprehensi_5

Accumulated Other Comprehensive Loss - Reclassification out of Accumulated Other Comprehensive Loss (Details) - Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] - Reclassification out of Accumulated Other Comprehensive Income [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization of net prior service cost	$ (4,095)	$ (793)	$ (794)
Amortization of net loss	57,650	38,070	5,586
Adjustment due to effects of regulation	(42,187)	(33,050)	(10,006)
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, before tax	11,368	4,227	(5,214)
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, tax	(2,387)	(888)	1,095
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, after tax	$ 8,981	$ 3,339	$ (4,119)

Earnings Per Common Share - Sch

Earnings Per Common Share - Schedule of Computation of Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net income	$ 155,176	$ 147,334	$ 129,488
Denominator:
Weighted-average number of common shares outstanding-basic	72,989	69,951	67,962
Effect of dilutive securities:
Performance and restricted stock awards	104	134	140
Weighted-average number of common shares outstanding-diluted	73,093	70,085	68,102
Earnings per common share:
Basic	$ 2.13	$ 2.11	$ 1.91
Diluted	$ 2.12	$ 2.10	$ 1.90

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	0	0	0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	1 Months Ended				12 Months Ended
	Apr. 30, 2022 USD ($) a	Jul. 31, 2021 USD ($)	Sep. 30, 2020 a	Aug. 31, 2019 USD ($)	Dec. 31, 2022 Lawsuit Plaintiff	Jan. 16, 2023	Sep. 30, 2022	May 31, 2021 a Building	Sep. 02, 2020 a Building
Loss Contingencies [Line Items]
Owners percentage interest					15%
Natural and Cultural Damage Claim [Member]
Loss Contingencies [Line Items]
Litigation settlement damages claim amount | $		$ 2,000,000
Boyds Fire [Member] | Damage from Fire [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Loss contingency, damages sought, value | $				$ 4,400,000
Labor Day Windstorm [Member] | Damage from Fire [Member]
Loss Contingencies [Line Items]
Number of residential, commercial and other structures impacted | Building									230
Road fire covered area | a									25,000
Babb Road Fire [Member] | Damage from Fire [Member]
Loss Contingencies [Line Items]
Number of residential, commercial and other structures impacted | Building								220
Road fire covered area | a								15,000
Number of lawsuits filed seeking unspecified damages | Lawsuit					9
Number of subrogation actions filed | Lawsuit					6
Number of actions on behalf of individual plaintiffs | Plaintiff					2
Number of class action lawsuit | Lawsuit					1
System Unit Resource Protection Act [Member] | Natural and Cultural Damage Claim [Member]
Loss Contingencies [Line Items]
Increased potential claim | $		$ 6,000,000
Colstrip [Member]
Loss Contingencies [Line Items]
Agreement voting requirement					NorthWestern has initiated arbitration pursuant to the O&O Agreement to resolve these business disagreements, and two actions have been initiated to compel arbitration of those disputes: one by Talen in the Montana Thirteenth Judicial District Court for Yellowstone County, and one by the Western Co-Owners, which is pending in Montana Federal District Court. In light of the ownership agreements discussed below, the Colstrip owners agreed to stay both the litigation and the arbitration until March 2023, at which time the proceedings would resume absent additional agreement between the owners.
Washington [Member]
Loss Contingencies [Line Items]
Wildfires covered area which damaged several residential structures, (in acres) | a			5
Avista Corp [Member] | Road Eleven Fire [Member] | Damage from Fire [Member]
Loss Contingencies [Line Items]
Loss contingency, damages sought, value | $	$ 5,000,000
Road fire covered area | a	10,000
PSE [Member] | Colstrip [Member] | Unit 3 [Member]
Loss Contingencies [Line Items]
Owners percentage interest					25%		25%
PSE [Member] | Colstrip [Member] | Unit 4 [Member]
Loss Contingencies [Line Items]
Owners percentage interest					25%		25%
NorthWestern [Member] | Colstrip [Member] | Unit 3 [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Owners percentage interest						15%
NorthWestern [Member] | Colstrip [Member] | Unit 4 [Member]
Loss Contingencies [Line Items]
Owners percentage interest					30%
NorthWestern [Member] | Colstrip [Member] | Unit 4 [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Owners percentage interest						15%

Commitments and Contingencies_2

Commitments and Contingencies - Ownership and Operating Interest Percentage (Details)	Dec. 31, 2022	Sep. 30, 2022
Loss Contingencies [Line Items]
Owners percentage interest	15%
Avista [Member] | Unit 3 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	15%
Avista [Member] | Unit 4 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	15%
Pacificorp [Member] | Unit 3 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	10%
Pacificorp [Member] | Unit 4 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	10%
PGE [Member] | Unit 3 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	20%
PGE [Member] | Unit 4 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	20%
PSE [Member] | Unit 3 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	25%	25%
PSE [Member] | Unit 4 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	25%	25%
NorthWestern [Member] | Unit 4 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	30%
Talen [Member] | Unit 3 [Member] | Colstrip [Member]
Loss Contingencies [Line Items]
Owners percentage interest	30%

Regulatory Matters - Schedule o

Regulatory Matters - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulated Asset Liability [Line Items]
Earning a return, asset	$ 712,914
Not earning a return, asset	285,816
Pending regulatory treatment, asset	28,385
Regulatory assets	193,787	$ 43,783
Non-current regulatory assets	833,328	860,626
Earning a return, liability	853,865
Not earning a return, liability	51,628
Pending Regulatory Treatment Liability	31,009
Regulatory liabilities	95,665	77,149
Non-current regulatory liabilities	840,837	861,515
Deferred Power Costs [Member]
Regulated Asset Liability [Line Items]
Earning a return, liability	0
Not earning a return, liability	0
Pending Regulatory Treatment Liability	0
Regulatory liabilities	0	6,457
Non-current regulatory liabilities	0	5,434
Utility Plant Retirement Costs [Member]
Regulated Asset Liability [Line Items]
Earning a return, liability	376,817
Not earning a return, liability	0
Pending Regulatory Treatment Liability	0
Regulatory liabilities	0	0
Non-current regulatory liabilities	376,817	350,190
Income Tax Related Liabilities [Member]
Regulated Asset Liability [Line Items]
Earning a return, liability	427,365
Not earning a return, liability	27,458
Pending Regulatory Treatment Liability	9,178
Regulatory liabilities	73,267	56,331
Non-current regulatory liabilities	390,734	458,789
Interest Rate Swaps [Member]
Regulated Asset Liability [Line Items]
Earning a return, liability	13,020
Not earning a return, liability	0
Pending Regulatory Treatment Liability	11,184
Regulatory liabilities	0	0
Non-current regulatory liabilities	$ 24,204	15,062
Decoupling Rebates [Member]
Regulated Asset Liability [Line Items]
Remaining amortization period, regulatory liability	3 years
Earning a return, liability	$ 29,945
Not earning a return, liability	0
Pending Regulatory Treatment Liability	0
Regulatory liabilities	9,469	3,049
Non-current regulatory liabilities	20,476	6,259
COVID-19 Deferrals [Member]
Regulated Asset Liability [Line Items]
Earning a return, liability	0
Not earning a return, liability	1,227
Pending Regulatory Treatment Liability	10,647
Regulatory liabilities	0	0
Non-current regulatory liabilities	11,874	12,500
Other Regulatory Liabilities [Member]
Regulated Asset Liability [Line Items]
Earning a return, liability	6,718
Not earning a return, liability	22,943
Pending Regulatory Treatment Liability	0
Regulatory liabilities	12,929	11,312
Non-current regulatory liabilities	16,732	13,281
Deferred Income Tax [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	240,325
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	0	0
Non-current regulatory assets	240,325	244,154
Pension and Other Postretirement Benefit Plans [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	0
Not earning a return, asset	135,337
Pending regulatory treatment, asset	0
Regulatory assets	0	0
Non-current regulatory assets	135,337	165,696
Energy commodity derivatives
Regulated Asset Liability [Line Items]
Earning a return, asset	0
Not earning a return, asset	130,275
Pending regulatory treatment, asset	0
Regulatory assets	112,090	12,447
Non-current regulatory assets	18,185	2,938
Unamortized Debt Repurchase Costs [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	6,177
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	0	0
Non-current regulatory assets	$ 6,177	6,768
Settlement with Coeur d'Alene Tribe [Member]
Regulated Asset Liability [Line Items]
Remaining amortization period, regulatory assets	37 years
Earning a return, asset	$ 37,809
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	0	0
Non-current regulatory assets	37,809	38,926
Demand Side Management Programs [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	0
Not earning a return, asset	3,683
Pending regulatory treatment, asset	0
Regulatory assets	0	0
Non-current regulatory assets	$ 3,683	3,974
Decoupling Surcharge [Member]
Regulated Asset Liability [Line Items]
Remaining amortization period, regulatory assets	3 years
Earning a return, asset	$ 11,699
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	6,250	9,907
Non-current regulatory assets	5,449	14,625
Utility Plant Abandoned [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	24,389
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	0	0
Non-current regulatory assets	24,389	26,771
Interest Rate Swaps [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	168,832
Not earning a return, asset	0
Pending regulatory treatment, asset	17,087
Regulatory assets	0	0
Non-current regulatory assets	185,919	199,754
Deferred power costs [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	47,399
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	23,356	7,334
Non-current regulatory assets	24,043	3,501
Deferred Natural Gas Costs [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	52,091
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	52,091	14,095
Non-current regulatory assets	0	6,932
AFUDC Above FERC Allowed Rate [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	51,649
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	0	0
Non-current regulatory assets	51,649	48,455
COVID-19 Deferrals [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	0
Not earning a return, asset	1,650
Pending regulatory treatment, asset	8,143
Regulatory assets	0	0
Non-current regulatory assets	9,793	13,591
Advanced Meter Infrastructure [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	32,381
Not earning a return, asset	0
Pending regulatory treatment, asset	0
Regulatory assets	0	0
Non-current regulatory assets	32,381	36,008
Other Regulatory Assets [Member]
Regulated Asset Liability [Line Items]
Earning a return, asset	40,163
Not earning a return, asset	14,871
Pending regulatory treatment, asset	3,155
Regulatory assets	0	0
Non-current regulatory assets	$ 58,189	$ 48,533

Regulatory Matters - Schedule_2

Regulatory Matters - Schedule of Regulatory Assets and Liabilities (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017
Regulated Asset Liability [Line Items]
Federal statutory tax rate	21%	21%	21%	21%	35%
Avista Utilities [Member]
Regulated Asset Liability [Line Items]
Tax cuts and jobs act period to return plant related excess deferred income taxes	33 years
Alaska Electric Light & Power [Member]
Regulated Asset Liability [Line Items]
Tax cuts and jobs act period to return plant related excess deferred income taxes	22 years

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulated Asset Liability [Line Items]
Threshold limit of deadband and sharing bands for future surcharge or rebate to customer	$ 4,000,000
Company share of benefit (expense) under washington energy recovery mechanism	(10,900,000)	$ (7,700,000)
Threshold to return washington energy recovery mechanism dollars to customers	$ 30,000,000
Proposed cumulative rebate refund period	1 year
Deferred natural gas costs, asset	$ 52,100,000	21,000,000
WASHINGTON
Regulated Asset Liability [Line Items]
Decoupling maximum rate increase request	3%
WASHINGTON | Power Deferrals Regulatory Asset [Member]
Regulated Asset Liability [Line Items]
Regulatory assets	$ 30,500,000
IDAHO | Power Deferrals Regulatory Asset [Member]
Regulated Asset Liability [Line Items]
Regulatory assets	16,300,000	10,800,000
Power Deferrals Regulatory Liability [Member] | WASHINGTON
Regulated Asset Liability [Line Items]
Regulatory liabilities		11,900,000
Revenue Subject to Refund [Member] | WASHINGTON
Regulated Asset Liability [Line Items]
Regulatory liabilities	0	0
Revenue Subject to Refund [Member] | IDAHO
Regulated Asset Liability [Line Items]
Regulatory liabilities	686,000	686,000
Revenue Subject to Refund [Member] | OREGON
Regulated Asset Liability [Line Items]
Regulatory liabilities	$ 0	$ 0

Regulatory Matters - Schedule_3

Regulatory Matters - Schedule of Decoupling and Earnings Sharing Mechanisms (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
WASHINGTON | Decoupling (Rebate) Surcharge [Member]
Scheduleof Decouplingand Earnings Sharing [Line Items]
Regulatory assets		$ 13,522,000
Regulatory Liabilities	$ (13,210,000)
WASHINGTON | Revenue Subject to Refund [Member]
Scheduleof Decouplingand Earnings Sharing [Line Items]
Regulatory Liabilities	0	0
IDAHO | Decoupling (Rebate) Surcharge [Member]
Scheduleof Decouplingand Earnings Sharing [Line Items]
Regulatory Liabilities	(7,889,000)	(1,450,000)
IDAHO | Revenue Subject to Refund [Member]
Scheduleof Decouplingand Earnings Sharing [Line Items]
Regulatory Liabilities	(686,000)	(686,000)
OREGON | Decoupling (Rebate) Surcharge [Member]
Scheduleof Decouplingand Earnings Sharing [Line Items]
Regulatory assets	2,853,000	3,152,000
OREGON | Revenue Subject to Refund [Member]
Scheduleof Decouplingand Earnings Sharing [Line Items]
Regulatory Liabilities	$ 0	$ 0

Information by Business Segme_3

Information by Business Segments - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 ReportableSegments
Segment Reporting [Abstract]
Number of reportable segments	2

Information by Business Segme_4

Information by Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 1,710,207	$ 1,438,936	$ 1,321,891
Resource costs	735,862	497,123	398,509
Other operating expenses	416,768	372,052	359,958
Depreciation and amortization	253,142	232,176	224,223
Income (loss) from operations	190,242	228,232	232,700
Interest expense	118,692	106,152	105,061
Income taxes	(17,191)	12,031	7,051
Net income (loss)	155,176	147,334	129,488
Capital expenditures	452,829	441,209	405,674
Total Assets	7,417,350	6,853,583	6,402,097
Avista Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,663,815	1,392,999	1,277,468
Alaska Electric Light & Power [Member]
Segment Reporting Information [Line Items]
Operating revenues	45,704	45,366	42,809
Operating Segments [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,709,519	1,438,365	1,320,277
Resource costs	735,862	497,123	398,509
Other operating expenses	405,165	366,125	354,614
Depreciation and amortization	253,017	231,915	223,507
Income (loss) from operations	201,282	233,849	237,146
Interest expense	118,173	105,725	104,723
Income taxes	(25,031)	8,792	7,932
Net income (loss)	125,446	132,782	132,905
Capital expenditures	451,995	439,939	404,306
Total Assets	7,240,486	6,723,666	6,304,311
Operating Segments [Member] | Avista Utilities [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,663,815	1,392,999	1,277,468
Resource costs	732,298	493,289	396,543
Other operating expenses	390,597	352,241	341,709
Depreciation and amortization	242,198	221,552	213,701
Income (loss) from operations	185,582	217,663	220,058
Interest expense	112,213	99,629	98,451
Income taxes	(27,368)	6,029	4,921
Net income (loss)	117,901	125,558	124,810
Capital expenditures	443,373	435,887	397,292
Total Assets	6,976,164	6,458,244	6,035,340
Operating Segments [Member] | Alaska Electric Light & Power [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	45,704	45,366	42,809
Resource costs	3,564	3,834	1,966
Other operating expenses	14,568	13,884	12,905
Depreciation and amortization	10,819	10,363	9,806
Income (loss) from operations	15,700	16,186	17,088
Interest expense	5,960	6,096	6,272
Income taxes	2,337	2,763	3,011
Net income (loss)	7,545	7,224	8,095
Capital expenditures	8,622	4,052	7,014
Total Assets	264,322	265,422	268,971
Other [Member] | Non-Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues	688	571	1,614
Resource costs	0	0	0
Other operating expenses	11,603	5,927	5,344
Depreciation and amortization	125	261	716
Income (loss) from operations	(11,040)	(5,617)	(4,446)
Interest expense	791	522	524
Income taxes	7,840	3,239	(881)
Net income (loss)	29,730	14,552	(3,417)
Capital expenditures	834	1,270	1,368
Total Assets	187,027	132,158	109,658
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0	0
Resource costs	0	0	0
Other operating expenses	0	0	0
Depreciation and amortization	0	0	0
Income (loss) from operations	0	0	0
Interest expense	(272)	(95)	(186)
Income taxes	0	0	0
Net income (loss)	0	0	0
Capital expenditures	0	0	0
Total Assets	$ (10,163)	$ (2,241)	$ (11,872)