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AVA Avista

Document and Entity Information

Document and Entity Information - shares3 Months Ended
Mar. 31, 2021Apr. 30, 2021
Cover [Abstract]
Entity Registrant NameAVISTA CORPORATION
Amendment Flagfalse
Entity Filer CategoryLarge Accelerated Filer
Entity Small Businessfalse
Entity Information, Former Legal or Registered NameNone
City Area Code509
Entity Incorporation, State or Country CodeWA
Document Transition Reportfalse
Document Quarterly Reporttrue
Document Type10-Q
Document Period End DateMar. 31,
2021
Entity File Number1-3701
Entity Tax Identification Number91-0462470
Entity Address, Address Line One1411 East Mission Avenue
Entity Address, City or TownSpokane
Entity Address, State or ProvinceWA
Entity Address, Postal Zip Code99202-2600
Local Phone Number489-0500
Entity Current Reporting StatusYes
Entity Interactive Data CurrentYes
Entity Emerging Growth Companyfalse
Entity Shell Companyfalse
Document Fiscal Year Focus2021
Document Fiscal Period FocusQ1
Entity Central Index Key0000104918
Current Fiscal Year End Date--12-31
Entity Common Stock, Shares Outstanding69,314,368
Title of 12(b) SecurityCommon Stock
Trading SymbolAVA
Security Exchange NameNYSE

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Utility revenues:
Utility revenues, exclusive of alternative revenue programs $ 412,182 $ 393,820
Alternative revenue programs499 (4,413)
Total utility revenues412,681 389,407
Non-utility revenues189 823
Total operating revenues412,870 390,230
Utility operating expenses:
Resource costs134,579 129,547
Other operating expenses87,555 94,496
Depreciation and amortization55,221 51,421
Taxes other than income taxes32,309 30,978
Non-utility operating expenses:
Other operating expenses1,184 1,360
Depreciation and amortization127 235
Total operating expenses310,975 308,037
Income from operations101,895 82,193
Interest expense26,304 26,347
Interest expense to affiliated trusts109 270
Capitalized interest(1,015)(998)
Other income-net(3,684)(382)
Income before income taxes80,181 56,956
Income tax expense12,164 8,532
Net income $ 68,017 $ 48,424
Weighted-average common shares outstanding (thousands), basic69,293 67,239
Weighted-average common shares outstanding (thousands), diluted69,506 67,381
Earnings per common share:
Basic $ 0.98 $ 0.72
Diluted $ 0.98 $ 0.72

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income $ 68,017 $ 48,424
Other Comprehensive Income:
Change in unfunded benefit obligation for pension and other postretirement benefit plans - net of taxes of $84 and $54 respectively315 205
Total other comprehensive income315 205
Comprehensive income $ 68,332 $ 48,629

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax $ 84 $ 54

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Current Assets:
Cash and cash equivalents $ 21,647 $ 14,196
Accounts and notes receivable-less allowances of $12,139 and $11,387, respectively153,128 163,772
Materials and supplies, fuel stock and stored natural gas63,160 67,451
Regulatory assets29,225 13,673
Other current assets82,922 84,885
Total current assets350,082 343,977
Net utility property5,027,103 4,991,612
Goodwill52,426 52,426
Non-current regulatory assets705,921 750,443
Other property and investments-net and other non-current assets263,964 263,639
Total assets6,399,496 6,402,097
Current Liabilities:
Accounts payable93,100 106,613
Short-term borrowings193,000 203,000
Regulatory liabilities45,067 46,435
Other current liabilities161,632 149,831
Total current liabilities492,799 505,879
Long-term debt2,008,742 2,008,534
Long-term debt to affiliated trusts51,547 51,547
Pensions and other postretirement benefits199,670 211,880
Deferred income taxes607,707 594,712
Non-current regulatory liabilities783,784 784,820
Other non-current liabilities and deferred credits186,657 214,999
Total liabilities4,330,906 4,372,371
Commitments and Contingencies (See Notes to Condensed Consolidated Financial Statements)
Shareholders’ Equity:
Common stock, no par value; 200,000,000 shares authorized; 69,313,337 and 69,238,901 shares issued and outstanding, respectively1,285,999 1,286,068
Accumulated other comprehensive loss(14,063)(14,378)
Retained earnings796,654 758,036
Total shareholders’ equity2,068,590 2,029,726
Total liabilities and equity $ 6,399,496 $ 6,402,097

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Statement Of Financial Position [Abstract]
Accounts and notes receivable, allowances $ 12,139 $ 11,387
Common stock, par value $ 0 $ 0
Common stock, shares authorized200,000,000 200,000,000
Common stock, shares, issued69,313,337 69,238,901
Common stock, shares outstanding69,313,337 69,238,901

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Operating Activities:
Net income $ 68,017 $ 48,424
Non-cash items included in net income:
Depreciation and amortization55,348 51,421
Deferred income tax provision and investment tax credits5,966 (6,765)
Power and natural gas cost amortizations (deferrals), net(7,811)6,380
Amortization of debt expense823 653
Stock-based compensation expense626 872
Equity-related AFUDC(1,754)(1,599)
Pension and other postretirement benefit expense7,556 7,952
Other regulatory assets and liabilities and deferred debits and credits1,762 11,902
Change in decoupling regulatory deferral(682)4,155
Gain on sale of investments(155)(3,242)
Other(2,828)5,112
Contributions to defined benefit pension plan(14,000)(7,300)
Changes in certain current assets and liabilities:
Accounts and notes receivable6,728 6,078
Materials and supplies, fuel stock and stored natural gas4,291 9,901
Collateral posted for derivative instruments1,497 (14,283)
Income taxes receivable5,442 10,500
Income taxes payable557 4,901
Other current assets(260)(2,166)
Accounts payable(2,590)(19,527)
Other current liabilities16,557 21,905
Net cash provided by operating activities145,090 135,274
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)(97,203)(95,525)
Issuance of notes receivable(75)(2,779)
Equity and property investments(2,340)(1,313)
Proceeds from sale of investments801 5,148
Other2,356 (662)
Net cash used in investing activities(96,461)(95,131)
Financing Activities:
Net decrease in short-term borrowings(10,000)(800)
Maturity of long-term debt and finance leases(759)(700)
Issuance of common stock, net of issuance costs65 175
Cash dividends paid(29,399)(27,389)
Other(1,085)(2,406)
Net cash used in financing activities(41,178)(31,120)
Net increase in cash and cash equivalents7,451 9,023
Cash and cash equivalents at beginning of period14,196 9,896
Cash and cash equivalents at end of period $ 21,647 $ 18,919

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in ThousandsTotalCommon Stock [Member]Accumulated Other Comprehensive Loss [Member]Retained Earnings [Member]
Beginning Balance (in shares) at Dec. 31, 201967,176,996
Shares issued115,237
Ending Balance (in shares) at Mar. 31, 202067,292,233
Beginning Balance at Dec. 31, 2019 $ 1,210,741 $ (10,259) $ 738,802
Equity compensation expense804
Issuance of common stock, net of issuance costs175
Payment of minimum tax withholdings for share-based payment awards(2,408)
Ending Balance at Mar. 31, 2020 $ 1,959,095 $ 1,209,312 (10,054)759,837
Other comprehensive income205 205
Net income $ 48,424 48,424
Cash dividends paid on common stock(27,389)
Dividends declared per common share $ 0.4050
Beginning Balance (in shares) at Dec. 31, 202069,238,901 69,238,901
Shares issued74,436
Ending Balance (in shares) at Mar. 31, 202169,313,337 69,313,337
Beginning Balance at Dec. 31, 2020 $ 1,286,068 (14,378)758,036
Equity compensation expense859
Issuance of common stock, net of issuance costs65
Payment of minimum tax withholdings for share-based payment awards(993)
Ending Balance at Mar. 31, 2021 $ 2,068,590 $ 1,285,999 (14,063)796,654
Other comprehensive income315 $ 315
Net income $ 68,017 68,017
Cash dividends paid on common stock $ (29,399)
Dividends declared per common share $ 0.4225

Summary of Significant Accounti

Summary of Significant Accounting Policies3 Months Ended
Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting PoliciesNOTE 1. SUMMARY OF SIGNIFICANT 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 16 for business segment information. Basis of Reporting The condensed 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 condensed consolidated financial statements include the Company’s proportionate share of utility plant and related operations resulting from its interests in jointly owned plants. 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. Derivative Assets and Liabilities Derivatives are recorded as either assets or liabilities on the Condensed 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 rate 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 Condensed 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, as well as derivatives related to interest rate swaps and foreign currency exchange contracts, are reported at estimated fair value on the Condensed Consolidated Balance Sheets. See Note 11 for the Company’s fair value disclosures. 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. See Note 15 for further discussion of the Company's commitments and contingencies.

New Accounting Standards

New Accounting Standards3 Months Ended
Mar. 31, 2021
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
New Accounting StandardsNOTE 2. NEW ACCOUNTING STANDARDS There are no new accounting standards with a material impact to the Company.

Balance Sheet Components

Balance Sheet Components3 Months Ended
Mar. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet ComponentsNOTE 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 our regulated operations and the lower of cost or market for our non-regulated operations and consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Materials and supplies
$
56,368
$
53,258
Fuel stock
4,843
4,658
Stored natural gas
1,949
9,535
Total
$
63,160
$
67,451
Other Current Assets Other current assets consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Collateral posted for derivative instruments after netting with outstanding derivative liabilities
$
4,810
$
4,336
Prepayments
25,984
24,411
Income taxes receivable
44,371
49,814
Other
7,757
6,324
Total
$
82,922
$
84,885
Net Utility Property Net utility property consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Utility plant in service
$
6,865,652
$
6,809,797
Construction work in progress
193,685
175,767
Total
7,059,337
6,985,564
Less: Accumulated depreciation and amortization
2,032,234
1,993,952
Total net utility property
$
5,027,103
$
4,991,612
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 March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Operating lease ROU assets
$
71,410
$
71,891
Finance lease ROU assets
46,428
47,338
Non-utility property
18,398
19,508
Equity investments
61,132
59,318
Investment in affiliated trust
11,547
11,547
Notes receivable
14,665
14,454
Deferred compensation assets
9,469
9,174
Assets held for sale (1)
3,363
3,462
Other
27,552
26,947
Total
$
263,964
$
263,639
(1) The Company is in the process of selling certain subsidiary assets associated with Steam Plant Square and Brew Pub. Other Current Liabilities Other current liabilities consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Accrued taxes other than income taxes
$
56,630
$
45,099
Derivative liabilities
8,644
14,008
Employee paid time off accruals
28,775
26,495
Accrued interest
28,920
17,083
Pensions and other postretirement benefits
10,512
11,987
Other
28,151
35,159
Total other current liabilities
$
161,632
$
149,831
Other Non-Current Liabilities and Deferred Credits Other non-current liabilities and deferred credits consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Operating lease liabilities
$
68,276
$
67,716
Finance lease liabilities
48,044
48,815
Deferred investment tax credits
29,728
29,866
Asset retirement obligations
17,126
17,194
Derivative liabilities
8,959
37,427
Other
14,524
13,981
Total
$
186,657
$
214,999
Regulatory Assets and Liabilities Regulatory assets and liabilities consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Current
Non-Current
Current
Non-Current
Regulatory Assets
Energy commodity derivatives
$
3,637
$
3,237
$
2,073
$
5,722
Decoupling surcharge
18,150
6,812
7,123
17,123
Pension and other postretirement benefit plans

196,153

198,746
Interest rate swaps

177,824

214,851
Deferred income taxes

111,537

108,517
Settlement with Coeur d'Alene Tribe

39,764

40,043
AFUDC above FERC allowed rate

48,270

47,393
Demand side management programs

904

3,814
Utility plant to be abandoned

27,599

28,916
COVID-19 deferrals

11,759

8,166
Other regulatory assets
7,438
82,062
4,477
77,152
Total regulatory assets
$
29,225
$
705,921
$
13,673
$
750,443
Regulatory Liabilities
Income tax related liabilities
$
15,013
$
395,859
$
14,952
$
399,677
Deferred power costs
18,955
13,859
20,299
17,570
Decoupling rebate
1,396
1,604
1,447
1,519
Utility plant retirement costs

330,897

325,832
Interest rate swaps

17,218

15,046
COVID-19 deferrals

11,628

10,949
Other regulatory liabilities
9,703
12,719
9,737
14,227
Total regulatory liabilities
$
45,067
$
783,784
$
46,435
$
784,820

Revenue

Revenue3 Months Ended
Mar. 31, 2021
Revenue From Contract With Customer [Abstract]
RevenueNOTE 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. Given that 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 Condensed Consolidated Statements of Income in the line item "Utility revenues, exclusive of alternative revenue programs." 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 a 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 face of the Condensed 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 Condensed 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 that 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 current period Condensed Consolidated Statement 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 that 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. 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. 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 that are imposed on Avista Utilities as opposed to being imposed on its 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 three months ended March 31 (dollars in thousands):
2021
2020
Utility-related taxes
$
19,696
$
18,700
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 and, depending on the timing of the customer payments, it can result in an immaterial amount of deferred revenue or a receivable from the customer. As of March 31, 2021, the Company estimates it had unsatisfied capacity performance obligations of $21.2 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 three months ended March 31 (dollars in thousands):
2021
2020
Avista Utilities
Revenue from contracts with customers
$
358,613
$
351,628
Derivative revenues
34,981
31,075
Alternative revenue programs
499
(4,413
)
Deferrals and amortizations for rate refunds to customers
3,189
(2,606
)
Other utility revenues
2,578
1,521
Total Avista Utilities
399,860
377,205
AEL&P
Revenue from contracts with customers
12,779
12,126
Deferrals and amortizations for rate refunds to customers
(47
)
(48
)
Other utility revenues
89
124
Total AEL&P
12,821
12,202
Other revenues
189
823
Total operating revenues
$
412,870
$
390,230
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 three months ended March 31 (dollars in thousands):
2021
2020
Avista Utilities
AEL&P
Total Utility
Avista Utilities
AEL&P
Total Utility
Three months ended March 31,
ELECTRIC OPERATIONS
Revenue from contracts with customers
Residential
$
113,223
$
6,048
$
119,271
$
107,977
$
5,866
$
113,843
Commercial and governmental
76,284
4,772
81,056
78,849
6,199
85,048
Industrial
24,711
1,899
26,610
24,711

24,711
Public street and highway lighting
1,852
60
1,912
1,783
61
1,844
Total retail revenue
216,070
12,779
228,849
213,320
12,126
225,446
Transmission
3,495

3,495
3,774

3,774
Other revenue from contracts with customers
6,140

6,140
5,289

5,289
Total electric revenue from contracts with customers
$
225,705
$
12,779
$
238,484
$
222,383
$
12,126
$
234,509
The following table disaggregates revenue from contracts with customers associated with the Company's natural gas operations for the three months ended March 31 (dollars in thousands):
2021
2020
Avista Utilities
Avista Utilities
Three months ended March 31,
NATURAL GAS OPERATIONS
Revenue from contracts with customers
Residential
$
87,501
$
84,173
Commercial and governmental
39,775
39,401
Industrial and interruptible
2,224
2,194
Total retail revenue
129,500
125,768
Transportation
2,283
2,352
Other revenue from contracts with customers
1,125
1,125
Total natural gas revenue from contracts with customers
$
132,908
$
129,245

Derivatives and Risk Management

Derivatives and Risk Management3 Months Ended
Mar. 31, 2021
Derivative Instruments And Hedges [Abstract]
Derivatives and Risk ManagementNOTE 5. 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, Avista Corp. 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 March 31, 2021 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) MWh
Financial (1) MWh
Physical (1) mmBTUs
Financial (1) mmBTUs
Physical (1) MWh
Financial (1) MWh
Physical (1) mmBTUs
Financial (1) mmBTUs
Remainder 2021
3
92
7,434
48,028
40
754
8,045
29,520
2022


450
29,345


1,360
12,950
2023



6,920


1,360
1,970
2024






1,370

2025






1,115

As of March 31, 2021, there are no expected deliveries of energy commodity derivatives after 2025. The following table presents the underlying energy commodity derivative volumes as of December 31, 2020 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) MWh
Financial (1) MWh
Physical (1) mmBTUs
Financial (1) mmBTUs
Physical (1) MWh
Financial (1) MWh
Physical (1) mmBTUs
Financial (1) mmBTUs
2021
1
224
10,353
65,188
17
451
5,448
39,273
2022


450
25,525


1,360
12,030
2023



4,950


1,360
900
2024






1,370

2025






1,115

As of December 31, 2020, there are no expected deliveries of energy commodity derivatives after 2025.
(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 March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Number of contracts
25
22
Notional amount (in United States dollars)
$
4,916
$
3,860
Notional amount (in Canadian dollars)
6,178
4,949
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 March 31, 2021 and December 31, 2020 (dollars in thousands):
Balance Sheet Date
Number of Contracts
Notional Amount
Mandatory Cash Settlement Date
March 31, 2021
4
45,000
2021
12
130,000
2022
1
10,000
2023
December 31, 2020
4
45,000
2021
11
120,000
2022
1
10,000
2023 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 Condensed Consolidated Balance Sheet as of March 31, 2021 and December 31, 2020 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 Condensed Consolidated Balance Sheet as of March 31, 2021 (in thousands):
Fair Value
Derivative and Balance Sheet Location
Gross Asset
Gross Liability
Collateral Netted
Net Asset (Liability) on Balance Sheet
Foreign currency exchange derivatives
Other current liabilities
$

$
(22
)
$

$
(22
)
Interest rate swap derivatives
Other current assets
1,743


1,743
Other property and investments-net and other non-current assets
4,613
(3,820
)

793
Other current liabilities

(10,978
)
3,910
(7,068
)
Other non-current liabilities and deferred credits
1,264
(5,525
)

(4,261
)
Energy commodity derivatives
Other current assets
749
(24
)

725
Other property and investments-net and other non-current assets
2,598
(1,136
)

1,462
Other current liabilities
17,458
(21,820
)
2,786
(1,576
)
Other non-current liabilities and deferred credits
95
(4,793
)

(4,698
)
Total derivative instruments recorded on the balance sheet
$
28,520
$
(48,118
)
$
6,696
$
(12,902
) The following table presents the fair values and locations of derivative instruments recorded on the Condensed Consolidated Balance Sheet as of December 31, 2020 (in thousands):
Fair Value
Derivative and Balance Sheet Location
Gross Asset
Gross Liability
Collateral Netted
Net Asset (Liability) on Balance Sheet
Foreign currency exchange derivatives
Other current assets
$
30
$

$

$
30
Interest rate swap derivatives
Other current liabilities

(19,575
)
8,050
(11,525
)
Other non-current liabilities and deferred credits
952
(32,190
)

(31,238
)
Energy commodity derivatives
Other current assets
9,203
(8,306
)

897
Other property and investments-net and other non-current assets
1,755
(1,159
)

596
Other current liabilities
11,037
(14,007
)
487
(2,483
)
Other non-current liabilities and deferred credits
1,725
(8,043
)
129
(6,189
)
Total derivative instruments recorded on the balance sheet
$
24,702
$
(83,280
)
$
8,666
$
(49,912
) 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 March 31, 2021 and December 31, 2020 (in thousands):
March 31,
December 31,
2021
2020
Energy commodity derivatives
Cash collateral posted
$
7,596
$
4,953
Letters of credit outstanding
12,500
23,500
Balance sheet offsetting
2,786
616
Interest rate swap derivatives
Cash collateral posted (offset by net derivative positions)
3,910
8,050
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 March 31, 2021 and December 31, 2020 (in thousands):
March 31,
December 31,
2021
2020
Interest rate swap derivatives
Liabilities with credit-risk-related contingent features
14,956
50,813
Additional collateral to post
11,046
42,763

Pension Plans and Other Postret

Pension Plans and Other Postretirement Benefit Plans3 Months Ended
Mar. 31, 2021
General Discussion Of Pension And Other Postretirement Benefits [Abstract]
Pension Plans and Other Postretirement Benefit PlansNOTE 6. PENSION PLANS AND OTHER POSTRETIREMENT BENEFIT PLANS Avista Utilities Avista Utilities’ maintained the same pension and other postretirement plans during the three months ended March 31, 2021 as those described as of December 31, 2020. 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 $14 million in cash to the pension plan for the three months ended March 31, 2021 and it expects to contribute $42 million in 2021. The Company uses a December 31 measurement date for its defined benefit pension and other postretirement benefit plans. The following table sets forth the components of net periodic benefit costs for the three months ended March 31 (dollars in thousands):
Pension Benefits
Other Postretirement Benefits
2021
2020
2021
2020
Service cost
$
6,246
$
5,546
$
1,008
$
979
Interest cost
6,580
6,971
1,376
1,515
Expected return on plan assets
(9,775
)
(9,125
)
(675
)
(630
)
Amortization of prior service cost
75
75
(275
)
(275
)
Net loss recognition
1,823
1,654
1,173
1,243
Net periodic benefit cost
$
4,949
$
5,121
$
2,607
$
2,832
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 non-service portion of costs in the table above are recorded to other expense below income from operations in the Condensed Consolidated Statements of Income or capitalized as a regulatory asset. Approximately 40 percent of the costs are capitalized to regulatory assets and 60 percent is expensed to the income statement.

Income Taxes

Income Taxes3 Months Ended
Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income TaxesNOTE 7. INCOME TAXES In accordance with interim reporting requirements, the Company uses an estimated annual effective tax rate for computing its provisions for income taxes. An estimate of annual income tax expense (or benefit) is made each interim period using estimates for annual pre-tax income, income tax adjustments, and tax credits. The estimated annual effective tax rates do not include discrete events such as tax law changes, examination settlements, accounting method changes, or adjustments to tax expense or benefits attributable to prior years. Discrete events are recorded in the interim period in which they occur or become known. The estimated annual tax rate is applied to year-to-date pre-tax income to determine income tax expense (or benefit) for the interim period consistent with the annual estimate. In subsequent interim periods, income tax expense (or benefit) for the period is computed as the difference between the year-to-date amount reported for the previous interim period and the current period’s year-to-date amount. The following table summarizes the significant factors impacting the difference between our effective tax rate and the federal statutory rate for the three months ended March 31 (dollars in thousands):
2021
2020
Federal income taxes at statutory rates
$
16,838
21.0
%
$
11,961
21.0
%
Increase (decrease) in tax resulting from:
Tax effect of regulatory treatment of utility plant differences
(3,240
)
(4.0
)
(2,402
)
(4.2
)
State income tax expense
552
0.7
1,227
2.1
Settlement of equity awards
930
1.1
165
0.3
Other
(2,916
)
(3.6
)
(2,419
)
(4.2
)
Total income tax expense
$
12,164
15.2
%
$
8,532
15.0
%

Committed Lines of Credit

Committed Lines of Credit3 Months Ended
Mar. 31, 2021
Short Term Borrowings [Abstract]
Committed Lines of CreditNOTE 8. COMMITTED LINES OF CREDIT Avista Corp. Avista Corp. has a committed line of credit with various financial institutions in the total amount of $400.0 million with an expiration date of April 2022, with 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. Balances outstanding and interest rates of borrowings (excluding letters of credit) under the Company’s revolving committed line of credit were as follows as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Balance outstanding at end of period
$
93,000
$
102,000
Letters of credit outstanding at end of period
$
16,618
$
27,618
Average interest rate at end of period
1.17
%
1.22
% As of March 31, 2021 and December 31, 2020, the borrowings outstanding under Avista Corp.'s committed line of credit were classified as short-term borrowings on the Condensed Consolidated Balance Sheet. AEL&P AEL&P has a committed line of credit in the amount of $25.0 million that expires in November 2024. As of March 31, 2021 and December 31, 2020, there were borrowings of $0 and $1.0 million, respectively, and there were no letters of credit outstanding under this committed line of credit. 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. NOTE 9. CREDIT AGREEMENT In April 2020, the Company entered into a one-year Credit Agreement with various financial institutions, in the amount of $100 million. The Company borrowed the entire $100.0 million in April 2020 and repaid the outstanding balance in April 2021.

Credit Agreement

Credit Agreement3 Months Ended
Mar. 31, 2021
Credit Agreement [Abstract]
Committed Lines of CreditNOTE 8. COMMITTED LINES OF CREDIT Avista Corp. Avista Corp. has a committed line of credit with various financial institutions in the total amount of $400.0 million with an expiration date of April 2022, with 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. Balances outstanding and interest rates of borrowings (excluding letters of credit) under the Company’s revolving committed line of credit were as follows as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Balance outstanding at end of period
$
93,000
$
102,000
Letters of credit outstanding at end of period
$
16,618
$
27,618
Average interest rate at end of period
1.17
%
1.22
% As of March 31, 2021 and December 31, 2020, the borrowings outstanding under Avista Corp.'s committed line of credit were classified as short-term borrowings on the Condensed Consolidated Balance Sheet. AEL&P AEL&P has a committed line of credit in the amount of $25.0 million that expires in November 2024. As of March 31, 2021 and December 31, 2020, there were borrowings of $0 and $1.0 million, respectively, and there were no letters of credit outstanding under this committed line of credit. 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. NOTE 9. CREDIT AGREEMENT In April 2020, the Company entered into a one-year Credit Agreement with various financial institutions, in the amount of $100 million. The Company borrowed the entire $100.0 million in April 2020 and repaid the outstanding balance in April 2021.

Long- Term Debt to Affiliated T

Long- Term Debt to Affiliated Trust3 Months Ended
Mar. 31, 2021
Long Term Debt To Affiliated Trust [Abstract]
Long- Term Debt To Affiliated TrustsNOTE 10. LONG-TERM DEBT 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 LIBOR plus 0.875 percent, calculated and reset quarterly. The distribution rates paid were as follows during the three months ended March 31, 2021 and the year ended December 31, 2020:
March 31,
December 31,
2021
2020
Low distribution rate
1.07
%
1.10
%
High distribution rate
1.10
%
2.79
%
Distribution rate at the end of the period
1.07
%
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. The 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 Condensed Consolidated Balance Sheets. Interest expense to affiliated trusts in the Condensed Consolidated Statements of Income represents interest expense on these debentures.

Fair Value

Fair Value3 Months Ended
Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair ValueNOTE 11. FAIR 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 and material capital leases) and long-term debt to affiliated trusts are reported at carrying value on the Condensed 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 measurement) and the lowest priority to fair values derived from unobservable inputs (Level 3 measurement). 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 Condensed Consolidated Balance Sheets as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Carrying Value
Estimated Fair Value
Carrying Value
Estimated Fair Value
Long-term debt (Level 2)
$
963,500
$
1,129,375
$
963,500
$
1,189,824
Long-term debt (Level 3)
1,060,000
1,081,300
1,060,000
1,235,248
Snettisham finance lease obligation (Level 3)
51,016
51,000
51,750
58,700
Long-term debt to affiliated trusts (Level 3)
51,547
43,815
51,547
43,815
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 85.00 to 136.39, where a par value of 100.0 represents the carrying value recorded on the Condensed 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 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 March 31, 2021 and December 31, 2020. The following table discloses by level within the fair value hierarchy the Company’s assets and liabilities measured and reported on the Condensed Consolidated Balance Sheets as of March 31, 2021 and December 31, 2020 at fair value on a recurring basis (dollars in thousands):
Level 1
Level 2
Level 3
Counterparty and Cash Collateral Netting (1)
Total
March 31, 2021
Assets:
Energy commodity derivatives
$

$
20,805
$

$
(18,618
)
$
2,187
Level 3 energy commodity derivatives:
Natural gas exchange agreement


95
(95
)

Interest rate swap derivatives

7,620

(5,084
)
2,536
Deferred compensation assets:
Mutual Funds:
Fixed income securities (2)
2,154



2,154
Equity securities (2)
7,115



7,115
Total
$
9,269
$
28,425
$
95
$
(23,797
)
$
13,992
Liabilities:
Energy commodity derivatives
$

$
21,477
$

$
(21,404
)
$
73
Level 3 energy commodity derivatives:
Natural gas exchange agreement


6,296
(95
)
6,201
Foreign currency exchange derivatives

22


22
Interest rate swap derivatives

20,323

(8,994
)
11,329
Total
$

$
41,822
$
6,296
$
(30,493
)
$
17,625
December 31, 2020
Assets:
Energy commodity derivatives
$

$
23,645
$

$
(22,152
)
$
1,493
Level 3 energy commodity derivatives:
Natural gas exchange agreement


75
(75
)

Foreign currency exchange derivatives

30


30
Interest rate swap derivatives

952

(952
)

Deferred compensation assets:
Mutual Funds:
Fixed income securities (2)
2,471



2,471
Equity securities (2)
6,228



6,228
Total
$
8,699
$
24,627
$
75
$
(23,179
)
$
10,222
Liabilities:
Energy commodity derivatives
$

$
23,030
$

$
(22,768
)
$
262
Level 3 energy commodity derivatives:
Natural gas exchange agreement


8,485
(75
)
8,410
Interest rate swap derivatives

51,765

(9,002
)
42,763
Total
$

$
74,795
$
8,485
$
(31,845
)
$
51,435
(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)
These assets are included in other property and investments-net and other non-current assets on the Condensed 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 Condensed Consolidated Balance Sheets is due to netting arrangements with certain counterparties. See Note 5 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. The balance disclosed in the table above excludes cash and cash equivalents of $0.2 million and $0.5 million as of March 31, 2021 and December 31, 2020, respectively. Level 3 Fair Value 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 March 31, 2021 (dollars in thousands):
Fair Value (Net) at
Valuation
Unobservable
Range and Weighted
March 31, 2021
Technique
Input
Average Price
Natural gas exchange agreement
$
(6,201
)
Internally derived weighted average cost of gas
Forward purchase
$1.84 - $2.85/mmBTU $2.21 Weighted Average
Forward sales prices
$1.90 - $4.25/mmBTU $3.53 Weighted Average
Purchase volumes
130,000 - 310,000 mmBTUs
Sales volumes
75,000 - 310,000 mmBTUs The following table presents activity for energy commodity derivative assets (liabilities) measured at fair value using significant unobservable inputs (Level 3) for the three months ended March 31 (dollars in thousands):
Natural Gas Exchange Agreement
Three months ended March 31, 2021:
Balance as of January 1, 2021
$
(8,410
)
Total gains (realized/unrealized):
Included in regulatory assets/liabilities (1)
3,220
Settlements
(1,011
)
Ending balance as of March 31, 2021 (2)
$
(6,201
)
Three months ended March 31, 2020:
Balance as of January 1, 2020
$
(2,976
)
Total gains (realized/unrealized):
Included in regulatory assets/liabilities (1)
485
Settlements
238
Ending balance as of March 31, 2020 (2)
$
(2,253
)
(1)
All gains and losses are included in other regulatory assets and liabilities. There were no gains and losses included in either net income or other comprehensive income during any of the periods presented in the table above.
(2)
There were no purchases, issuances or transfers from other categories of any derivatives instruments during the periods presented in the table above.

Common Stock

Common Stock3 Months Ended
Mar. 31, 2021
Stockholders Equity Note [Abstract]
Common StockNOTE 12. COMMON STOCK The Company has authority to issue a maximum of approximately 3.2 million shares under its sales agency agreements, of which approximately 1.3 million shares remain unissued as of March 31, 2021. The Company has board authority, and has requested regulatory authority, to issue 3.0 million shares in addition to the 1.3 million shares previously authorized but remaining unissued. During the three months ended March 31, 2021 and March 31, 2020, the Company did not issue shares under the sales agency agreements.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss3 Months Ended
Mar. 31, 2021
Accumulated Other Comprehensive Loss [Abstract]
Accumulated Other Comprehensive LossNOTE 13. ACCUMULATED OTHER COMPREHENSIVE LOSS Accumulated other comprehensive loss, net of tax, consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $3,738 and $3,822, respectively
$
14,063
$
14,378
The following table details the reclassifications out of accumulated other comprehensive loss to net income by component for the three months ended March 31 (dollars in thousands):
Amounts Reclassified from Accumulated Other Comprehensive Loss
Details about Accumulated Other Comprehensive Loss Components (Affected Line Item in Statement of Income)
2021
2020
Amortization of defined benefit pension items
Amortization of net prior service cost (a)
$
(200
)
$
(200
)
Amortization of net loss (a)
3,191
3,100
Adjustment due to effects of regulation (a)
(2,592
)
(2,641
)
Total before tax (b)
399
259
Tax expense (b)
(84
)
(54
)
Net of tax (b)
$
315
$
205
(a)
These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 6 for additional details).
(b)
Description is also the affected line item on the Condensed Consolidated Statement of Income.

Earnings Per Common Share

Earnings Per Common Share3 Months Ended
Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Common ShareNOTE 14. EARNINGS PER COMMON SHARE The following table presents the computation of basic and diluted earnings per common share for the three months ended March 31 (in thousands, except per share amounts):
2021
2020
Numerator:
Net income
$
68,017
$
48,424
Denominator:
Weighted-average number of common shares outstanding-basic
69,293
67,239
Effect of dilutive securities:
Performance and restricted stock awards
213
142
Weighted-average number of common shares outstanding-diluted
69,506
67,381
Earnings per common share:
Basic
$
0.98
$
0.72
Diluted
$
0.98
$
0.72
There were no shares excluded from the calculation because they were antidilutive.

Commitments and Contingencies

Commitments and Contingencies3 Months Ended
Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and ContingenciesNOTE 15. COMMITMENTS 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 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 and subsequently consolidated into a single action. The Company intends to vigorously defend itself in the litigation. However, the Company cannot predict the outcome of these matters. Labor Day Windstorm In September 2020, a severe windstorm occurred in eastern Washington and northern Idaho. The extreme weather event resulted in customer outages and the cause of multiple wildfires in the region. With respect to wildfires, 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. 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); and the Mile Marker 49 fire (near Orofino, Idaho). These wildfires covered, in total, approximately 22,000 acres. The Company currently estimates approximately 230 residential, commercial and other structures were impacted. Parallel investigations by applicable state agencies, including the Washington Department of Natural Resources, are ongoing, and the Company is cooperating with those efforts. The Company’s investigation has found no evidence of negligence with respect to any of the fires, and the Company intends to vigorously defend any claims for damages that may be asserted against it with respect to the wildfires arising out of the extreme wind event. Colstrip The Washington CETA imposes deadlines by which coal-fired resources, such as Colstrip, must be excluded from the rate base of Washington utilities and by which electricity from such resources may no longer be delivered to Washington retail customers. Not all of the co-owners of Colstrip Units 3 & 4 are Washington utilities subject to CETA, and the co-owners have differing needs for the generating capacity of these units. Accordingly, business disagreements have arisen among the co-owners, including, but not limited to, disagreements as to the shut-down date or dates of these units. These business disagreements, in turn, have led to disagreements as to the interpretation of the Ownership and Operating Agreement, including, but not limited to, the rights of the co-owners to discontinue operations of, or otherwise terminate their interest in, Unit 3 and/or Unit 4. In order to address and resolve these disagreements, the owners have commenced an arbitration proceeding as provided for in the Ownership and Operating Agreement. In the course of the 2021 legislative session, the Montana Legislature passed two bills specifically directed at the ownership and operation of Colstrip. The first, Montana Senate Bill 265, purports to amend Section 27-5-323 of the Montana Code to provide that an agreement designating venue or disputes involving an electric generation facility located in Montana is not valid unless it requires arbitration in Montana before a panel of three arbitrators. The Ownership and Operating Agreement for Colstrip Units 3 & 4 includes an arbitration provision, through which all owners agreed to resolve disputes regarding the Agreement through arbitration in Spokane County, Washington before a single arbitrator. The Company, together with Puget Sound Energy, Portland General Electric, and PacifiCorp (Pacific Northwest Colstrip owners), has commenced an action in Spokane County Superior Court to compel arbitration of the pending disputes regarding interpretation of the Ownership & Operating Agreement in accordance with the requirements of the parties’ Agreement. The Pacific Northwest Colstrip owners have also commenced action in the U.S. District Court for the District of Montana to challenge the legality and constitutionality of the legislation. The Montana Legislature has also passed Montana Senate Bill 266, which would make it an unfair or deceptive act or practice, within the meaning of Montana’s Consumer Protection Act, for one or more owners of a jointly owned electrical generation facility to fail to fund its share of operating costs associated with that facility, or to engage in any conduct that would bring about a permanent closure of one or more generating units of such a facility without first obtaining the consent of all co-owners of that facility. The Company intends to challenge the legality and constitutionality of this bill as well. The Company is not able 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. 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. See "Note 22 of the Notes to Consolidated Financial Statements" in the 2020 Form 10-K for additional discussion regarding other contingencies.

Information by Business Segment

Information by Business Segments3 Months Ended
Mar. 31, 2021
Segment Reporting [Abstract]
Information by Business SegmentsNOTE 16. 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 Utilities
Alaska Electric Light and Power Company
Total Utility
Other
Intersegment Eliminations (1)
Total
For the three months ended March 31, 2021:
Operating revenues
$
399,860
$
12,821
$
412,681
$
189
$

$
412,870
Resource costs
133,840
739
134,579


134,579
Other operating expenses
84,599
2,956
87,555
1,184

88,739
Depreciation and amortization
52,724
2,497
55,221
127

55,348
Income (loss) from operations
96,693
6,324
103,017
(1,122
)

101,895
Interest expense (2)
24,800
1,525
26,325
129
(41
)
26,413
Income taxes
10,718
1,333
12,051
113

12,164
Net income
64,058
3,476
67,534
483

68,017
Capital expenditures (3)
96,394
809
97,203
28

97,231
For the three months ended March 31, 2020:
Operating revenues
$
377,205
$
12,202
$
389,407
$
823
$

$
390,230
Resource costs
129,557
(10
)
129,547


129,547
Other operating expenses
91,279
3,217
94,496
1,360

95,856
Depreciation and amortization
48,974
2,447
51,421
235

51,656
Income (loss) from operations
76,534
6,246
82,780
(587
)

82,193
Interest expense (2)
24,983
1,589
26,572
131
(86
)
26,617
Income taxes
7,404
1,301
8,705
(173
)

8,532
Net income (loss)
45,979
3,395
49,374
(950
)

48,424
Capital expenditures (3)
94,056
1,470
95,526
109

95,635
Total Assets:
As of March 31, 2021:
$
6,031,502
$
270,554
$
6,302,056
$
110,117
$
(12,677
)
$
6,399,496
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.
(2)
Including interest expense to affiliated trusts.
(3)
The capital expenditures for the other businesses are included in other investing activities on the Condensed Consolidated Statements of Cash Flows.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)3 Months Ended
Mar. 31, 2021
Accounting Policies [Abstract]
Nature of BusinessNature 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 16 for business segment information.
Basis of ReportingBasis of Reporting The condensed 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 condensed consolidated financial statements include the Company’s proportionate share of utility plant and related operations resulting from its interests in jointly owned plants.
RegulationRegulation 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.
Derivative Assets and LiabilitiesDerivative Assets and Liabilities Derivatives are recorded as either assets or liabilities on the Condensed 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 rate 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 Condensed Consolidated Balance Sheets.
Fair Value MeasurementsFair 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, as well as derivatives related to interest rate swaps and foreign currency exchange contracts, are reported at estimated fair value on the Condensed Consolidated Balance Sheets. See Note 11 for the Company’s fair value disclosures.
ContingenciesContingencies 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. See Note 15 for further discussion of the Company's commitments and contingencies.
InventoryMaterials 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 our regulated operations and the lower of cost or market for our non-regulated operations and consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Materials and supplies
$
56,368
$
53,258
Fuel stock
4,843
4,658
Stored natural gas
1,949
9,535
Total
$
63,160
$
67,451

Balance Sheet Components (Table

Balance Sheet Components (Tables)3 Months Ended
Mar. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Materials and Supplies, Fuel Stock and Stored Natural GasInventories of materials and supplies, fuel stock and stored natural gas are recorded at average cost for our regulated operations and the lower of cost or market for our non-regulated operations and consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Materials and supplies
$
56,368
$
53,258
Fuel stock
4,843
4,658
Stored natural gas
1,949
9,535
Total
$
63,160
$
67,451
Schedule of Other Current AssetsOther current assets consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Collateral posted for derivative instruments after netting with outstanding derivative liabilities
$
4,810
$
4,336
Prepayments
25,984
24,411
Income taxes receivable
44,371
49,814
Other
7,757
6,324
Total
$
82,922
$
84,885
Schedule of Net Utility PropertyNet utility property consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Utility plant in service
$
6,865,652
$
6,809,797
Construction work in progress
193,685
175,767
Total
7,059,337
6,985,564
Less: Accumulated depreciation and amortization
2,032,234
1,993,952
Total net utility property
$
5,027,103
$
4,991,612
Other Property and Investments-Net and Other Non-Current AssetsOther property and investments-net and other non-current assets consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Operating lease ROU assets
$
71,410
$
71,891
Finance lease ROU assets
46,428
47,338
Non-utility property
18,398
19,508
Equity investments
61,132
59,318
Investment in affiliated trust
11,547
11,547
Notes receivable
14,665
14,454
Deferred compensation assets
9,469
9,174
Assets held for sale (1)
3,363
3,462
Other
27,552
26,947
Total
$
263,964
$
263,639
(1) The Company is in the process of selling certain subsidiary assets associated with Steam Plant Square and Brew Pub.
Other Current LiabilitiesOther current liabilities consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Accrued taxes other than income taxes
$
56,630
$
45,099
Derivative liabilities
8,644
14,008
Employee paid time off accruals
28,775
26,495
Accrued interest
28,920
17,083
Pensions and other postretirement benefits
10,512
11,987
Other
28,151
35,159
Total other current liabilities
$
161,632
$
149,831
Schedule of Other Non-Current Liabilities and Deferred CreditsOther non-current liabilities and deferred credits consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Operating lease liabilities
$
68,276
$
67,716
Finance lease liabilities
48,044
48,815
Deferred investment tax credits
29,728
29,866
Asset retirement obligations
17,126
17,194
Derivative liabilities
8,959
37,427
Other
14,524
13,981
Total
$
186,657
$
214,999
Schedule of Regulatory Assets and LiabilitiesRegulatory assets and liabilities consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Current
Non-Current
Current
Non-Current
Regulatory Assets
Energy commodity derivatives
$
3,637
$
3,237
$
2,073
$
5,722
Decoupling surcharge
18,150
6,812
7,123
17,123
Pension and other postretirement benefit plans

196,153

198,746
Interest rate swaps

177,824

214,851
Deferred income taxes

111,537

108,517
Settlement with Coeur d'Alene Tribe

39,764

40,043
AFUDC above FERC allowed rate

48,270

47,393
Demand side management programs

904

3,814
Utility plant to be abandoned

27,599

28,916
COVID-19 deferrals

11,759

8,166
Other regulatory assets
7,438
82,062
4,477
77,152
Total regulatory assets
$
29,225
$
705,921
$
13,673
$
750,443
Regulatory Liabilities
Income tax related liabilities
$
15,013
$
395,859
$
14,952
$
399,677
Deferred power costs
18,955
13,859
20,299
17,570
Decoupling rebate
1,396
1,604
1,447
1,519
Utility plant retirement costs

330,897

325,832
Interest rate swaps

17,218

15,046
COVID-19 deferrals

11,628

10,949
Other regulatory liabilities
9,703
12,719
9,737
14,227
Total regulatory liabilities
$
45,067
$
783,784
$
46,435
$
784,820

Revenue (Tables)

Revenue (Tables)3 Months Ended
Mar. 31, 2021
Revenue From Contract With Customer [Abstract]
Schedule of Utilities Operating Revenue Expense TaxesUtility-related taxes that were included in revenue from contracts with customers were as follows for the three months ended March 31 (dollars in thousands):
2021
2020
Utility-related taxes
$
19,696
$
18,700
Disaggregation of RevenueDisaggregation of Total Operating Revenue The following table disaggregates total operating revenue by segment and source for the three months ended March 31 (dollars in thousands):
2021
2020
Avista Utilities
Revenue from contracts with customers
$
358,613
$
351,628
Derivative revenues
34,981
31,075
Alternative revenue programs
499
(4,413
)
Deferrals and amortizations for rate refunds to customers
3,189
(2,606
)
Other utility revenues
2,578
1,521
Total Avista Utilities
399,860
377,205
AEL&P
Revenue from contracts with customers
12,779
12,126
Deferrals and amortizations for rate refunds to customers
(47
)
(48
)
Other utility revenues
89
124
Total AEL&P
12,821
12,202
Other revenues
189
823
Total operating revenues
$
412,870
$
390,230
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 three months ended March 31 (dollars in thousands):
2021
2020
Avista Utilities
AEL&P
Total Utility
Avista Utilities
AEL&P
Total Utility
Three months ended March 31,
ELECTRIC OPERATIONS
Revenue from contracts with customers
Residential
$
113,223
$
6,048
$
119,271
$
107,977
$
5,866
$
113,843
Commercial and governmental
76,284
4,772
81,056
78,849
6,199
85,048
Industrial
24,711
1,899
26,610
24,711

24,711
Public street and highway lighting
1,852
60
1,912
1,783
61
1,844
Total retail revenue
216,070
12,779
228,849
213,320
12,126
225,446
Transmission
3,495

3,495
3,774

3,774
Other revenue from contracts with customers
6,140

6,140
5,289

5,289
Total electric revenue from contracts with customers
$
225,705
$
12,779
$
238,484
$
222,383
$
12,126
$
234,509
The following table disaggregates revenue from contracts with customers associated with the Company's natural gas operations for the three months ended March 31 (dollars in thousands):
2021
2020
Avista Utilities
Avista Utilities
Three months ended March 31,
NATURAL GAS OPERATIONS
Revenue from contracts with customers
Residential
$
87,501
$
84,173
Commercial and governmental
39,775
39,401
Industrial and interruptible
2,224
2,194
Total retail revenue
129,500
125,768
Transportation
2,283
2,352
Other revenue from contracts with customers
1,125
1,125
Total natural gas revenue from contracts with customers
$
132,908
$
129,245

Derivatives and Risk Manageme_2

Derivatives and Risk Management (Tables)3 Months Ended
Mar. 31, 2021
Derivative Instruments And Hedges [Abstract]
Schedule of Energy Commodity Derivative VolumesThe following table presents the underlying energy commodity derivative volumes as of March 31, 2021 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) MWh
Financial (1) MWh
Physical (1) mmBTUs
Financial (1) mmBTUs
Physical (1) MWh
Financial (1) MWh
Physical (1) mmBTUs
Financial (1) mmBTUs
Remainder 2021
3
92
7,434
48,028
40
754
8,045
29,520
2022


450
29,345


1,360
12,950
2023



6,920


1,360
1,970
2024






1,370

2025






1,115

As of March 31, 2021, there are no expected deliveries of energy commodity derivatives after 2025. The following table presents the underlying energy commodity derivative volumes as of December 31, 2020 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) MWh
Financial (1) MWh
Physical (1) mmBTUs
Financial (1) mmBTUs
Physical (1) MWh
Financial (1) MWh
Physical (1) mmBTUs
Financial (1) mmBTUs
2021
1
224
10,353
65,188
17
451
5,448
39,273
2022


450
25,525


1,360
12,030
2023



4,950


1,360
900
2024






1,370

2025






1,115

As of December 31, 2020, there are no expected deliveries of energy commodity derivatives after 2025.
(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 DerivativesThe following table summarizes the foreign currency exchange derivatives that Avista Corp. has outstanding as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Number of contracts
25
22
Notional amount (in United States dollars)
$
4,916
$
3,860
Notional amount (in Canadian dollars)
6,178
4,949
Summary of Unsettled Interest Rate Swap DerivativesThe following table summarizes the unsettled interest rate swap derivatives that Avista Corp. has outstanding as of March 31, 2021 and December 31, 2020 (dollars in thousands):
Balance Sheet Date
Number of Contracts
Notional Amount
Mandatory Cash Settlement Date
March 31, 2021
4
45,000
2021
12
130,000
2022
1
10,000
2023
December 31, 2020
4
45,000
2021
11
120,000
2022
1
10,000
2023
Schedules of Fair Values and Locations of Derivative InstrumentsThe following table presents the fair values and locations of derivative instruments recorded on the Condensed Consolidated Balance Sheet as of March 31, 2021 (in thousands):
Fair Value
Derivative and Balance Sheet Location
Gross Asset
Gross Liability
Collateral Netted
Net Asset (Liability) on Balance Sheet
Foreign currency exchange derivatives
Other current liabilities
$

$
(22
)
$

$
(22
)
Interest rate swap derivatives
Other current assets
1,743


1,743
Other property and investments-net and other non-current assets
4,613
(3,820
)

793
Other current liabilities

(10,978
)
3,910
(7,068
)
Other non-current liabilities and deferred credits
1,264
(5,525
)

(4,261
)
Energy commodity derivatives
Other current assets
749
(24
)

725
Other property and investments-net and other non-current assets
2,598
(1,136
)

1,462
Other current liabilities
17,458
(21,820
)
2,786
(1,576
)
Other non-current liabilities and deferred credits
95
(4,793
)

(4,698
)
Total derivative instruments recorded on the balance sheet
$
28,520
$
(48,118
)
$
6,696
$
(12,902
) The following table presents the fair values and locations of derivative instruments recorded on the Condensed Consolidated Balance Sheet as of December 31, 2020 (in thousands):
Fair Value
Derivative and Balance Sheet Location
Gross Asset
Gross Liability
Collateral Netted
Net Asset (Liability) on Balance Sheet
Foreign currency exchange derivatives
Other current assets
$
30
$

$

$
30
Interest rate swap derivatives
Other current liabilities

(19,575
)
8,050
(11,525
)
Other non-current liabilities and deferred credits
952
(32,190
)

(31,238
)
Energy commodity derivatives
Other current assets
9,203
(8,306
)

897
Other property and investments-net and other non-current assets
1,755
(1,159
)

596
Other current liabilities
11,037
(14,007
)
487
(2,483
)
Other non-current liabilities and deferred credits
1,725
(8,043
)
129
(6,189
)
Total derivative instruments recorded on the balance sheet
$
24,702
$
(83,280
)
$
8,666
$
(49,912
)
Schedule of Collateral Outstanding Related to Derivative InstrumentsThe following table presents Avista Corp.'s collateral outstanding related to its derivative instruments as of March 31, 2021 and December 31, 2020 (in thousands):
March 31,
December 31,
2021
2020
Energy commodity derivatives
Cash collateral posted
$
7,596
$
4,953
Letters of credit outstanding
12,500
23,500
Balance sheet offsetting
2,786
616
Interest rate swap derivatives
Cash collateral posted (offset by net derivative positions)
3,910
8,050
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 March 31, 2021 and December 31, 2020 (in thousands):
March 31,
December 31,
2021
2020
Interest rate swap derivatives
Liabilities with credit-risk-related contingent features
14,956
50,813
Additional collateral to post
11,046
42,763

Pension Plans and Other Postr_2

Pension Plans and Other Postretirement Benefit Plans (Tables)3 Months Ended
Mar. 31, 2021
General Discussion Of Pension And Other Postretirement Benefits [Abstract]
Components of Net Periodic Benefit CostThe following table sets forth the components of net periodic benefit costs for the three months ended March 31 (dollars in thousands):
Pension Benefits
Other Postretirement Benefits
2021
2020
2021
2020
Service cost
$
6,246
$
5,546
$
1,008
$
979
Interest cost
6,580
6,971
1,376
1,515
Expected return on plan assets
(9,775
)
(9,125
)
(675
)
(630
)
Amortization of prior service cost
75
75
(275
)
(275
)
Net loss recognition
1,823
1,654
1,173
1,243
Net periodic benefit cost
$
4,949
$
5,121
$
2,607
$
2,832

Income Taxes (Tables)

Income Taxes (Tables)3 Months Ended
Mar. 31, 2021
Income Tax Disclosure [Abstract]
Summary of Significant Factors Impact on Difference Between Effective Tax Rate and Federal Statutory RateThe following table summarizes the significant factors impacting the difference between our effective tax rate and the federal statutory rate for the three months ended March 31 (dollars in thousands):
2021
2020
Federal income taxes at statutory rates
$
16,838
21.0
%
$
11,961
21.0
%
Increase (decrease) in tax resulting from:
Tax effect of regulatory treatment of utility plant differences
(3,240
)
(4.0
)
(2,402
)
(4.2
)
State income tax expense
552
0.7
1,227
2.1
Settlement of equity awards
930
1.1
165
0.3
Other
(2,916
)
(3.6
)
(2,419
)
(4.2
)
Total income tax expense
$
12,164
15.2
%
$
8,532
15.0
%

Committed Lines of Credit (Tabl

Committed Lines of Credit (Tables)3 Months Ended
Mar. 31, 2021
Short Term Borrowings [Abstract]
Schedule of Balances Outstanding and Interest Rates of Borrowings (Excluding Letters of Credit)Balances outstanding and interest rates of borrowings (excluding letters of credit) under the Company’s revolving committed line of credit were as follows as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31,
December 31,
2021
2020
Balance outstanding at end of period
$
93,000
$
102,000
Letters of credit outstanding at end of period
$
16,618
$
27,618
Average interest rate at end of period
1.17
%
1.22
%

Long- Term Debt to Affiliated_2

Long- Term Debt to Affiliated Trust (Tables)3 Months Ended
Mar. 31, 2021
Long Term Debt To Affiliated Trust [Abstract]
Schedule Of Distribution Rates PaidThe distribution rates paid were as follows during the three months ended March 31, 2021 and the year ended December 31, 2020:
March 31,
December 31,
2021
2020
Low distribution rate
1.07
%
1.10
%
High distribution rate
1.10
%
2.79
%
Distribution rate at the end of the period
1.07
%
1.10
%

Fair Value (Tables)

Fair Value (Tables)3 Months Ended
Mar. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of Carrying Value and Estimated Fair Value of Financial InstrumentsThe 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 Condensed Consolidated Balance Sheets as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Carrying Value
Estimated Fair Value
Carrying Value
Estimated Fair Value
Long-term debt (Level 2)
$
963,500
$
1,129,375
$
963,500
$
1,189,824
Long-term debt (Level 3)
1,060,000
1,081,300
1,060,000
1,235,248
Snettisham finance lease obligation (Level 3)
51,016
51,000
51,750
58,700
Long-term debt to affiliated trusts (Level 3)
51,547
43,815
51,547
43,815
Schedule of Fair Value of Assets and Liabilities Measured on Recurring BasisThe following table discloses by level within the fair value hierarchy the Company’s assets and liabilities measured and reported on the Condensed Consolidated Balance Sheets as of March 31, 2021 and December 31, 2020 at fair value on a recurring basis (dollars in thousands):
Level 1
Level 2
Level 3
Counterparty and Cash Collateral Netting (1)
Total
March 31, 2021
Assets:
Energy commodity derivatives
$

$
20,805
$

$
(18,618
)
$
2,187
Level 3 energy commodity derivatives:
Natural gas exchange agreement


95
(95
)

Interest rate swap derivatives

7,620

(5,084
)
2,536
Deferred compensation assets:
Mutual Funds:
Fixed income securities (2)
2,154



2,154
Equity securities (2)
7,115



7,115
Total
$
9,269
$
28,425
$
95
$
(23,797
)
$
13,992
Liabilities:
Energy commodity derivatives
$

$
21,477
$

$
(21,404
)
$
73
Level 3 energy commodity derivatives:
Natural gas exchange agreement


6,296
(95
)
6,201
Foreign currency exchange derivatives

22


22
Interest rate swap derivatives

20,323

(8,994
)
11,329
Total
$

$
41,822
$
6,296
$
(30,493
)
$
17,625
December 31, 2020
Assets:
Energy commodity derivatives
$

$
23,645
$

$
(22,152
)
$
1,493
Level 3 energy commodity derivatives:
Natural gas exchange agreement


75
(75
)

Foreign currency exchange derivatives

30


30
Interest rate swap derivatives

952

(952
)

Deferred compensation assets:
Mutual Funds:
Fixed income securities (2)
2,471



2,471
Equity securities (2)
6,228



6,228
Total
$
8,699
$
24,627
$
75
$
(23,179
)
$
10,222
Liabilities:
Energy commodity derivatives
$

$
23,030
$

$
(22,768
)
$
262
Level 3 energy commodity derivatives:
Natural gas exchange agreement


8,485
(75
)
8,410
Interest rate swap derivatives

51,765

(9,002
)
42,763
Total
$

$
74,795
$
8,485
$
(31,845
)
$
51,435
(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)
These assets are included in other property and investments-net and other non-current assets on the Condensed Consolidated Balance Sheets.
Schedule of Quantitative InformationThe following table presents the quantitative information which was used to estimate the fair values of the Level 3 assets and liabilities above as of March 31, 2021 (dollars in thousands):
Fair Value (Net) at
Valuation
Unobservable
Range and Weighted
March 31, 2021
Technique
Input
Average Price
Natural gas exchange agreement
$
(6,201
)
Internally derived weighted average cost of gas
Forward purchase
$1.84 - $2.85/mmBTU $2.21 Weighted Average
Forward sales prices
$1.90 - $4.25/mmBTU $3.53 Weighted Average
Purchase volumes
130,000 - 310,000 mmBTUs
Sales volumes
75,000 - 310,000 mmBTUs
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 energy commodity derivative assets (liabilities) measured at fair value using significant unobservable inputs (Level 3) for the three months ended March 31 (dollars in thousands):
Natural Gas Exchange Agreement
Three months ended March 31, 2021:
Balance as of January 1, 2021
$
(8,410
)
Total gains (realized/unrealized):
Included in regulatory assets/liabilities (1)
3,220
Settlements
(1,011
)
Ending balance as of March 31, 2021 (2)
$
(6,201
)
Three months ended March 31, 2020:
Balance as of January 1, 2020
$
(2,976
)
Total gains (realized/unrealized):
Included in regulatory assets/liabilities (1)
485
Settlements
238
Ending balance as of March 31, 2020 (2)
$
(2,253
)
(1)
All gains and losses are included in other regulatory assets and liabilities. There were no gains and losses included in either net income or other comprehensive income during any of the periods presented in the table above.
(2)
There were no purchases, issuances or transfers from other categories of any derivatives instruments during the periods presented in the table above.

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)3 Months Ended
Mar. 31, 2021
Accumulated Other Comprehensive Loss [Abstract]
Schedule of Accumulated Other Comprehensive Loss, Net of TaxAccumulated other comprehensive loss, net of tax, consisted of the following as of March 31, 2021 and December 31, 2020 (dollars in thousands):
March 31, 2021
December 31, 2020
Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $3,738 and $3,822, respectively
$
14,063
$
14,378
Reclassification out of Accumulated Other Comprehensive IncomeThe following table details the reclassifications out of accumulated other comprehensive loss to net income by component for the three months ended March 31 (dollars in thousands):
Amounts Reclassified from Accumulated Other Comprehensive Loss
Details about Accumulated Other Comprehensive Loss Components (Affected Line Item in Statement of Income)
2021
2020
Amortization of defined benefit pension items
Amortization of net prior service cost (a)
$
(200
)
$
(200
)
Amortization of net loss (a)
3,191
3,100
Adjustment due to effects of regulation (a)
(2,592
)
(2,641
)
Total before tax (b)
399
259
Tax expense (b)
(84
)
(54
)
Net of tax (b)
$
315
$
205
(a)
These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 6 for additional details).
(b)
Description is also the affected line item on the Condensed Consolidated Statement of Income.

Earnings Per Common (Tables)

Earnings Per Common (Tables)3 Months Ended
Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Earnings Per Common ShareThe following table presents the computation of basic and diluted earnings per common share for the three months ended March 31 (in thousands, except per share amounts):
2021
2020
Numerator:
Net income
$
68,017
$
48,424
Denominator:
Weighted-average number of common shares outstanding-basic
69,293
67,239
Effect of dilutive securities:
Performance and restricted stock awards
213
142
Weighted-average number of common shares outstanding-diluted
69,506
67,381
Earnings per common share:
Basic
$
0.98
$
0.72
Diluted
$
0.98
$
0.72

Information by Business Segme_2

Information by Business Segments (Tables)3 Months Ended
Mar. 31, 2021
Segment Reporting [Abstract]
Schedule of Business SegmentsThe following table presents information for each of the Company’s business segments (dollars in thousands):
Avista Utilities
Alaska Electric Light and Power Company
Total Utility
Other
Intersegment Eliminations (1)
Total
For the three months ended March 31, 2021:
Operating revenues
$
399,860
$
12,821
$
412,681
$
189
$

$
412,870
Resource costs
133,840
739
134,579


134,579
Other operating expenses
84,599
2,956
87,555
1,184

88,739
Depreciation and amortization
52,724
2,497
55,221
127

55,348
Income (loss) from operations
96,693
6,324
103,017
(1,122
)

101,895
Interest expense (2)
24,800
1,525
26,325
129
(41
)
26,413
Income taxes
10,718
1,333
12,051
113

12,164
Net income
64,058
3,476
67,534
483

68,017
Capital expenditures (3)
96,394
809
97,203
28

97,231
For the three months ended March 31, 2020:
Operating revenues
$
377,205
$
12,202
$
389,407
$
823
$

$
390,230
Resource costs
129,557
(10
)
129,547


129,547
Other operating expenses
91,279
3,217
94,496
1,360

95,856
Depreciation and amortization
48,974
2,447
51,421
235

51,656
Income (loss) from operations
76,534
6,246
82,780
(587
)

82,193
Interest expense (2)
24,983
1,589
26,572
131
(86
)
26,617
Income taxes
7,404
1,301
8,705
(173
)

8,532
Net income (loss)
45,979
3,395
49,374
(950
)

48,424
Capital expenditures (3)
94,056
1,470
95,526
109

95,635
Total Assets:
As of March 31, 2021:
$
6,031,502
$
270,554
$
6,302,056
$
110,117
$
(12,677
)
$
6,399,496
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.
(2)
Including interest expense to affiliated trusts.
(3)
The capital expenditures for the other businesses are included in other investing activities on the Condensed Consolidated Statements of Cash Flows.

Balance Sheet Components - Mate

Balance Sheet Components - Materials and Supplies, Fuel Stock and Stored Natural Gas (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Materials and supplies $ 56,368 $ 53,258
Fuel stock4,843 4,658
Stored natural gas1,949 9,535
Total $ 63,160 $ 67,451

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Other Current Assets (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Collateral posted for derivative instruments after netting with outstanding derivative liabilities $ 4,810 $ 4,336
Prepayments25,984 24,411
Income taxes receivable44,371 49,814
Other7,757 6,324
Total $ 82,922 $ 84,885

Balance Sheet Components - Net

Balance Sheet Components - Net Utility Property (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Utility plant in service $ 6,865,652 $ 6,809,797
Construction work in progress193,685 175,767
Total7,059,337 6,985,564
Less: Accumulated depreciation and amortization2,032,234 1,993,952
Total net utility property $ 5,027,103 $ 4,991,612

Balance Sheet Components - Othe

Balance Sheet Components - Other Property and Investments-Net and Other Non-current Assets (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Operating lease ROU assets $ 71,410 $ 71,891
Finance lease ROU assets46,428 47,338
Non-utility property18,398 19,508
Equity investments61,132 59,318
Investment in affiliated trust11,547 11,547
Notes receivable14,665 14,454
Deferred compensation assets9,469 9,174
Assets held for sale[1]3,363 3,462
Other27,552 26,947
Total $ 263,964 $ 263,639
[1]The Company is in the process of selling certain subsidiary assets associated with Steam Plant Square and Brew Pub

Balance Sheet Components - Ot_2

Balance Sheet Components - Other Current Liabilities (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accrued taxes other than income taxes $ 56,630 $ 45,099
Derivative liabilities8,644 14,008
Employee paid time off accruals28,775 26,495
Accrued interest28,920 17,083
Pensions and other postretirement benefits10,512 11,987
Other28,151 35,159
Total other current liabilities $ 161,632 $ 149,831

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Other Non-Current Liabilities and Deferred Credits (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Operating lease liabilities $ 68,276 $ 67,716
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]TotalTotal
Finance lease liabilities $ 48,044 $ 48,815
Deferred investment tax credits29,728 29,866
Asset retirement obligations17,126 17,194
Derivative liabilities8,959 37,427
Other14,524 13,981
Total $ 186,657 $ 214,999

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Regulated Asset Liability [Line Items]
Regulatory assets $ 29,225 $ 13,673
Non-current regulatory assets705,921 750,443
Regulatory liabilities45,067 46,435
Non-current regulatory liabilities783,784 784,820
Deferred Income Tax Charge [Member]
Regulated Asset Liability [Line Items]
Regulatory liabilities15,013 14,952
Non-current regulatory liabilities395,859 399,677
Power Deferrals Regulatory Liability [Member]
Regulated Asset Liability [Line Items]
Regulatory liabilities18,955 20,299
Non-current regulatory liabilities13,859 17,570
Decoupling Surcharge [Member]
Regulated Asset Liability [Line Items]
Regulatory liabilities1,396 1,447
Non-current regulatory liabilities1,604 1,519
Removal Costs [Member]
Regulated Asset Liability [Line Items]
Regulatory liabilities0 0
Non-current regulatory liabilities330,897 325,832
Interest Rate Swaps [Member]
Regulated Asset Liability [Line Items]
Regulatory liabilities0 0
Non-current regulatory liabilities17,218 15,046
COVID-19 Deferrals [Member]
Regulated Asset Liability [Line Items]
Regulatory liabilities0 0
Non-current regulatory liabilities11,628 10,949
Other Regulatory Assets (Liabilities) [Member]
Regulated Asset Liability [Line Items]
Regulatory liabilities9,703 9,737
Non-current regulatory liabilities12,719 14,227
Energy commodity derivatives
Regulated Asset Liability [Line Items]
Regulatory assets3,637 2,073
Non-current regulatory assets3,237 5,722
Decoupling Surcharge [Member]
Regulated Asset Liability [Line Items]
Regulatory assets18,150 7,123
Non-current regulatory assets6,812 17,123
Pension and Other Postretirement Benefit Plans [Member]
Regulated Asset Liability [Line Items]
Regulatory assets0 0
Non-current regulatory assets196,153 198,746
Interest Rate Swaps [Member]
Regulated Asset Liability [Line Items]
Regulatory assets0 0
Non-current regulatory assets177,824 214,851
Deferred Income Tax Charge [Member]
Regulated Asset Liability [Line Items]
Regulatory assets0 0
Non-current regulatory assets111,537 108,517
Settlement with Coeur d'Alene Tribe [Member]
Regulated Asset Liability [Line Items]
Regulatory assets0 0
Non-current regulatory assets39,764 40,043
AFUDC Above FERC Allowed Rate [Member]
Regulated Asset Liability [Line Items]
Regulatory assets0 0
Non-current regulatory assets48,270 47,393
Demand Side Management Programs [Member]
Regulated Asset Liability [Line Items]
Regulatory assets0 0
Non-current regulatory assets904 3,814
Utility Plant to be Abandoned [Member]
Regulated Asset Liability [Line Items]
Regulatory assets0 0
Non-current regulatory assets27,599 28,916
COVID-19 Deferrals [Member]
Regulated Asset Liability [Line Items]
Regulatory assets0 0
Non-current regulatory assets11,759 8,166
Other Regulatory Assets (Liabilities) [Member]
Regulated Asset Liability [Line Items]
Regulatory assets7,438 4,477
Non-current regulatory assets $ 82,062 $ 77,152

Revenue - Schedule of Utilities

Revenue - Schedule of Utilities Operating Revenue Expense Taxes (Details) - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Revenue From Contract With Customer [Abstract]
Utility-related taxes $ 19,696 $ 18,700

Revenue - Additional Informatio

Revenue - Additional Information (Details) $ in MillionsMar. 31, 2021USD ($)
Revenue From Contract With Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount $ 21.2

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues $ 412,870 $ 390,230
Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax119,271 113,843
Commercial and Governmental Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax81,056 85,048
Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax26,610 24,711
Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax1,912 1,844
Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax228,849 225,446
Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax3,495 3,774
Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax6,140 5,289
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax238,484 234,509
Avista Utilities [Member]
Disaggregation of Revenue [Line Items]
Revenues399,860 377,205
Avista Utilities [Member] | Revenue from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues358,613 351,628
Avista Utilities [Member] | Derivative revenues
Disaggregation of Revenue [Line Items]
Revenues34,981 31,075
Avista Utilities [Member] | Alternative Revenue Programs [Member]
Disaggregation of Revenue [Line Items]
Revenues499 (4,413)
Avista Utilities [Member] | Deferrals and Amortizations for Rate Refunds to Customers
Disaggregation of Revenue [Line Items]
Revenues3,189 (2,606)
Avista Utilities [Member] | Other Utility Revenues
Disaggregation of Revenue [Line Items]
Revenues2,578 1,521
Alaska Electric Light & Power [Member]
Disaggregation of Revenue [Line Items]
Revenues12,821 12,202
Alaska Electric Light & Power [Member] | Revenue from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues12,779 12,126
Alaska Electric Light & Power [Member] | Deferrals and Amortizations for Rate Refunds to Customers
Disaggregation of Revenue [Line Items]
Revenues(47)(48)
Alaska Electric Light & Power [Member] | Other Utility Revenues
Disaggregation of Revenue [Line Items]
Revenues89 124
Corporate and Other [Member] | Other Revenues
Disaggregation of Revenue [Line Items]
Revenues189 823
Avista Utilities [Member] | Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax113,223 107,977
Avista Utilities [Member] | Commercial and Governmental Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax76,284 78,849
Avista Utilities [Member] | Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax24,711 24,711
Avista Utilities [Member] | Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax1,852 1,783
Avista Utilities [Member] | Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax216,070 213,320
Avista Utilities [Member] | Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax3,495 3,774
Avista Utilities [Member] | Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax6,140 5,289
Avista Utilities [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax225,705 222,383
Avista Utilities [Member] | Residential Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax87,501 84,173
Avista Utilities [Member] | Commercial and Governmental Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax39,775 39,401
Avista Utilities [Member] | Industrial and Interruptible Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax2,224 2,194
Avista Utilities [Member] | Retail Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax129,500 125,768
Avista Utilities [Member] | Transportation Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax2,283 2,352
Avista Utilities [Member] | Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax132,908 129,245
Avista Utilities [Member] | Other Natural Gas Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax1,125 1,125
Alaska Electric Light & Power [Member] | Residential Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax6,048 5,866
Alaska Electric Light & Power [Member] | Commercial and Governmental Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax4,772 6,199
Alaska Electric Light & Power [Member] | Industrial Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax1,899 0
Alaska Electric Light & Power [Member] | Public Street and Highway Lighting Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax60 61
Alaska Electric Light & Power [Member] | Retail Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax12,779 12,126
Alaska Electric Light & Power [Member] | Transmission Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax0 0
Alaska Electric Light & Power [Member] | Other Electric Revenues from Contracts With Customers [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax0 0
Alaska Electric Light & Power [Member] | Electric [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer including assessed tax $ 12,779 $ 12,126

Derivatives and Risk Manageme_3

Derivatives and Risk Management - Schedule of Energy Commodity Derivative Volumes (Details) MWh in Thousands, MMBTU in Thousands3 Months Ended12 Months Ended
Mar. 31, 2021MWhMMBTUDec. 31, 2020MWhMMBTU
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh3 1
2022 | MWh0 0
2023 | MWh0 0
2024 | MWh0 0
2025 | MWh0 0
Purchase [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU7,434 10,353
2022 | MMBTU450 450
2023 | MMBTU0 0
2024 | MMBTU0 0
2025 | MMBTU0 0
Purchase [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh92 224
2022 | MWh0 0
2023 | MWh0 0
2024 | MWh0 0
2025 | MWh0 0
Purchase [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU48,028 65,188
2022 | MMBTU29,345 25,525
2023 | MMBTU6,920 4,950
2024 | MMBTU0 0
2025 | MMBTU0 0
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh40 17
2022 | MWh0 0
2023 | MWh0 0
2024 | MWh0 0
2025 | MWh0 0
Sales [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU8,045 5,448
2022 | MMBTU1,360 1,360
2023 | MMBTU1,360 1,360
2024 | MMBTU1,370 1,370
2025 | MMBTU1,115 1,115
Sales [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MWh754 451
2022 | MWh0 0
2023 | MWh0 0
2024 | MWh0 0
2025 | MWh0 0
Sales [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2021 | MMBTU29,520 39,273
2022 | MMBTU12,950 12,030
2023 | MMBTU1,970 900
2024 | MMBTU0 0
2025 | MMBTU0 0

Derivatives and Risk Manageme_4

Derivatives and Risk Management - Additional Information (Details)3 Months Ended12 Months Ended
Mar. 31, 2021MWhMMBTUDec. 31, 2020MWhMMBTU
Canadian [Member]
Derivative [Line Items]
Number of days Canadian currency prices are settled with U.S. dollars60 days
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MWh0 0
Purchase [Member] | Physical [Member] | Gas Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MMBTU0 0
Purchase [Member] | Financial [Member] | Electric Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MWh0 0
Purchase [Member] | Financial [Member] | Gas Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MMBTU0 0
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MWh0 0
Sales [Member] | Physical [Member] | Gas Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MMBTU0 0
Sales [Member] | Financial [Member] | Electric Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MWh0 0
Sales [Member] | Financial [Member] | Gas Derivative [Member]
Derivative [Line Items]
Expected deliveries of energy commodity derivatives after five years | MMBTU0 0

Derivatives and Risk Manageme_5

Derivatives and Risk Management - Summary of Foreign Currency Exchange Derivatives (Details) $ in Thousands, $ in ThousandsMar. 31, 2021USD ($)derivative_contractsMar. 31, 2021CAD ($)derivative_contractsDec. 31, 2020USD ($)derivative_contractsDec. 31, 2020CAD ($)derivative_contracts
Foreign Currency Fair Value Hedge Derivative [Line Items]
Number of contracts | derivative_contracts25 25 22 22
United States of America, Dollars [Member] | Foreign Exchange Contract [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Notional amount $ 4,916 $ 3,860
Canada, Dollars [Member] | Foreign Exchange Contract [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Notional amount $ 6,178 $ 4,949

Derivatives and Risk Manageme_6

Derivatives and Risk Management - Summary of Unsettled Interest Rate Swap Derivatives (Details) - Interest Rate Swap [Member] $ in Thousands3 Months Ended12 Months Ended
Mar. 31, 2021USD ($)ContractDec. 31, 2020USD ($)Contract
2021 [Member]
Derivatives, Fair Value [Line Items]
Number of Contracts | Contract4 4
Notional Amount | $ $ 45,000 $ 45,000
Mandatory Cash Settlement Date20212021
2022 [Member]
Derivatives, Fair Value [Line Items]
Number of Contracts | Contract12 11
Notional Amount | $ $ 130,000 $ 120,000
Mandatory Cash Settlement Date20222022
2023 [Member]
Derivatives, Fair Value [Line Items]
Number of Contracts | Contract1 1
Notional Amount | $ $ 10,000 $ 10,000
Mandatory Cash Settlement Date20232023

Derivatives and Risk Manageme_7

Derivatives and Risk Management - Schedules of Fair Values and Locations of Derivative Instruments (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Gross Asset $ 28,520 $ 24,702
Gross Liability(48,118)(83,280)
Collateral Netted6,696 8,666
Net Asset (Liability) on Balance Sheet(12,902)(49,912)
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Collateral Netted2,786 616
Other Current Liabilities [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset0
Gross Liability(22)
Collateral Netted0
Net Asset (Liability) on Balance Sheet(22)
Other Current Liabilities [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset0 0
Gross Liability(10,978)(19,575)
Collateral Netted3,910 8,050
Net Asset (Liability) on Balance Sheet(7,068)(11,525)
Other Current Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset17,458 11,037
Gross Liability(21,820)(14,007)
Collateral Netted2,786 487
Net Asset (Liability) on Balance Sheet(1,576)(2,483)
Other Current Assets [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset30
Gross Liability0
Collateral Netted0
Net Asset (Liability) on Balance Sheet30
Other Current Assets [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset1,743
Gross Liability0
Collateral Netted0
Net Asset (Liability) on Balance Sheet1,743
Other Current Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset749 9,203
Gross Liability(24)(8,306)
Collateral Netted0 0
Net Asset (Liability) on Balance Sheet725 897
Other Property And Investments Net And Other Non-current Assets [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset4,613
Gross Liability(3,820)
Collateral Netted0
Net Asset (Liability) on Balance Sheet793
Other Property And Investments Net And Other Non-current Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset2,598 1,755
Gross Liability(1,136)(1,159)
Collateral Netted0 0
Net Asset (Liability) on Balance Sheet1,462 596
Other Noncurrent Liabilities [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Asset1,264 952
Gross Liability(5,525)(32,190)
Collateral Netted0 0
Net Asset (Liability) on Balance Sheet(4,261)(31,238)
Other Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset95 1,725
Gross Liability(4,793)(8,043)
Collateral Netted0 129
Net Asset (Liability) on Balance Sheet $ (4,698) $ (6,189)

Derivatives and Risk Manageme_8

Derivatives and Risk Management - Schedule of Collateral Outstanding Related to Derivative Instruments (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Derivative [Line Items]
Balance sheet offsetting $ 6,696 $ 8,666
Commodity Contracts [Member]
Derivative [Line Items]
Cash collateral posted7,596 4,953
Letters of credit outstanding12,500 23,500
Balance sheet offsetting2,786 616
Interest Rate Swap [Member]
Derivative [Line Items]
Cash collateral posted3,910 8,050
Liabilities with credit-risk-related contingent features14,956 50,813
Additional collateral to post $ 11,046 $ 42,763

Pension Plans and Other Postr_3

Pension Plans and Other Postretirement Benefit Plans - Additional Information (Details) - USD ($)3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Payment for pension benefits $ 14,000,000 $ 7,300,000
Percentage of service related net periodic benefit costs capitalized to utility property40.00%
Percentage of service related net periodic benefit costs recorded to operating expenses60.00%
Percentage of non-service related net periodic benefit costs capitalized to regulatory assets40.00%
Percentage of non-service related net periodic benefit costs recorded to other expense60.00%
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions to pension plan $ 42,000,000

Pension Plans and Other Postr_4

Pension Plans and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost $ 6,246 $ 5,546
Interest cost6,580 6,971
Expected return on plan assets(9,775)(9,125)
Amortization of prior service cost75 75
Net loss recognition1,823 1,654
Net periodic benefit cost4,949 5,121
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost1,008 979
Interest cost1,376 1,515
Expected return on plan assets(675)(630)
Amortization of prior service cost(275)(275)
Net loss recognition1,173 1,243
Net periodic benefit cost $ 2,607 $ 2,832

Income Taxes - Summary of Signi

Income Taxes - Summary of Significant Factors Impact on Difference Between Effective Tax Rate and Federal Statutory Rate (Details) - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Income Tax Disclosure [Abstract]
Federal income taxes at statutory rates $ 16,838 $ 11,961
Tax effect of regulatory treatment of utility plant differences(3,240)(2,402)
State income tax expense552 1,227
Settlement of equity awards930 165
Other(2,916)(2,419)
Total income tax expense $ 12,164 $ 8,532
Federal income taxes at statutory rates21.00%21.00%
Tax effect of regulatory treatment of utility plant differences(4.00%)(4.20%)
State income tax expense0.70%2.10%
Settlement of equity awards1.10%0.30%
Other(3.60%)(4.20%)
Total income tax expense15.20%15.00%

Committed Lines of Credit - Add

Committed Lines of Credit - Additional Information (Details) - USD ($)3 Months Ended
Mar. 31, 2021Dec. 31, 2020Apr. 30, 2014
Avista Utilities [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity $ 400,000,000
Line of credit facility, expiration date2022-04
Line of credit facility additional expiration period1 year
Line of credit, current $ 93,000,000 $ 102,000,000
Letters of credit outstanding at end of period16,618,000 27,618,000
Alaska Electric Light & Power [Member]
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity $ 25,000,000
Line of credit facility, expiration date2024-11
Line of credit, current $ 0 1,000,000
Letters of credit outstanding at end of period $ 0 $ 0

Committed Lines of Credit - Sch

Committed Lines of Credit - Schedule of Balances Outstanding and Interest Rates of Borrowings (Excluding Letters of Credit) (Details) - Avista Utilities [Member] - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Short-term Debt [Line Items]
Balance outstanding at end of period $ 93,000 $ 102,000
Letters of credit outstanding at end of period $ 16,618 $ 27,618
Average interest rate at end of period1.17%1.22%

Credit Agreement - Additional I

Credit Agreement - Additional Information (Details) - Avista Utilities [Member] $ in Millions1 Months Ended
Apr. 30, 2020USD ($)
Short-term Debt [Line Items]
Credit agreement amount borrowed $ 100
Credit agreement, expiration month and year2021-04
Maximum borrowing capacity credit agreement $ 100

Long- Term Debt to Affiliated_3

Long- Term Debt to Affiliated Trust - Narrative (Details) - USD ($) $ in Millions3 Months Ended12 Months Ended
Mar. 31, 2021Dec. 31, 2000Dec. 31, 1997
Debt Instrument [Line Items]
Junior subordinated debenture owed to unconsolidated subsidiary trust $ 51.5 $ 51.5
Proceeds from the issuance of common trust securities1.5
Payments for repurchase of trust preferred securities $ 10
Avista Corp [Member]
Debt Instrument [Line Items]
Noncontrolling interest, ownership percentage by parent100.00%
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Debt Instrument [Line Items]
Proceeds from (repurchase of) trust preferred securities $ 50
Debt instrument, description of variable rate basisLIBOR
Debt instrument, basis spread on variable rate0.875%

Long-Term Debt to Affiliated Tr

Long-Term Debt to Affiliated Trust - Schedule of Distribution Rates Paid (Details) - Trust Preferred Securities Subject to Mandatory Redemption [Member]Mar. 31, 2021Dec. 31, 2020
Debt Instrument [Line Items]
Interest rate1.07%1.10%
Minimum [Member]
Debt Instrument [Line Items]
Interest rate1.07%1.10%
Maximum [Member]
Debt Instrument [Line Items]
Interest rate1.10%2.79%

Fair Value - Schedule of Carryi

Fair Value - Schedule of Carrying Value and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Level 2 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value $ 963,500 $ 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 Value1,129,375 1,189,824
Level 3 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value1,060,000 1,060,000
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, Liability51,016 51,750
Level 3 [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value1,081,300 1,235,248
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, Liability51,000 58,700
Affiliated Entity [Member] | Level 3 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value51,547 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 $ 43,815 $ 43,815

Fair Value - Additional Informa

Fair Value - Additional Information (Details) $ in ThousandsMar. 31, 2021USD ($)Dec. 31, 2020USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents $ 21,647 $ 14,196
Fixed Income Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents $ 200 $ 500
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 input100
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 input85
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 input136.39

Fair Value - Schedule of Fair V

Fair Value - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset $ 28,520 $ 24,702
Liability48,118 83,280
Fair Value, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure13,992 10,222
Financial Liabilities Fair Value Disclosure17,625 51,435
Counterparty and Cash Collateral Netting, Assets(23,797)(23,179)
Counterparty and Cash Collateral Netting, Liabilities(30,493)(31,845)
Fair Value, Recurring [Member] | Fixed Income Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:2,154 2,471
Fair Value, Recurring [Member] | Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:7,115 6,228
Fair Value, Recurring [Member] | Energy commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and Cash Collateral Netting, Assets(18,618)(22,152)
Derivative Asset2,187 1,493
Counterparty and Cash Collateral Netting, Liabilities(21,404)(22,768)
Derivative Liability73 262
Fair Value, Recurring [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and Cash Collateral Netting, Assets(5,084)(952)
Derivative Asset2,536
Counterparty and Cash Collateral Netting, Liabilities(8,994)(9,002)
Derivative Liability11,329 42,763
Fair Value, Recurring [Member] | Natural Gas Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and Cash Collateral Netting, Assets(95)(75)
Counterparty and Cash Collateral Netting, Liabilities(95)(75)
Derivative Liability6,201 8,410
Fair Value, Recurring [Member] | Foreign Exchange Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset30
Derivative Liability22
Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure9,269 8,699
Fair Value, Recurring [Member] | Level 1 [Member] | Fixed Income Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:2,154 2,471
Fair Value, Recurring [Member] | Level 1 [Member] | Equity Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:7,115 6,228
Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure28,425 24,627
Financial Liabilities Fair Value Disclosure41,822 74,795
Fair Value, Recurring [Member] | Level 2 [Member] | Energy commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset20,805 23,645
Liability21,477 23,030
Fair Value, Recurring [Member] | Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset7,620 952
Liability20,323 51,765
Fair Value, Recurring [Member] | Level 2 [Member] | Foreign Exchange Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset30
Liability22
Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, Fair Value Disclosure95 75
Financial Liabilities Fair Value Disclosure6,296 8,485
Fair Value, Recurring [Member] | Level 3 [Member] | Natural Gas Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset95 75
Liability $ 6,296 $ 8,485

Fair Value - Schedule of Quanti

Fair Value - Schedule of Quantitative Information (Details) - Natural Gas Exchange Agreements [Member] $ in Thousands3 Months Ended
Mar. 31, 2021USD ($)MMBTU$ / MMBTUDec. 31, 2020USD ($)
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 Price1.84
Transaction/Delivery Volumes | MMBTU130,000
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 Price2.85
Transaction/Delivery Volumes | MMBTU310,000
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 Price2.21
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 Price1.90
Transaction/Delivery Volumes | MMBTU75,000
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 Price4.25
Transaction/Delivery Volumes | MMBTU310,000
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 Price3.53
Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Derivative Liability | $ $ (6,201) $ (8,410)

Fair Value - Schedule of Activi

Fair Value - Schedule of Activity For Energy Commodity Derivative Assets (Liabilities) Measured At Fair Value Using Significant Unobservable Inputs (Level 3) (Details) - Natural Gas Exchange Agreements [Member] - Level 3 [Member] - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance $ (8,410) $ (2,976)
Included in regulatory assets/liabilities3,220 485
Settlements(1,011)238
Ending Balance $ (6,201) $ (2,253)

Common Stock - Narrative (Detai

Common Stock - Narrative (Details) - shares3 Months Ended
Mar. 31, 2021Mar. 31, 2020Dec. 31, 2020
Class Of Stock [Line Items]
Common stock, shares authorized200,000,000 200,000,000
Sales Agency Agreement [Member]
Class Of Stock [Line Items]
Common stock, shares authorized3,200,000
Common stock shares authorized under sales agency agreements remaining shares authorized to sell1,300,000
Number of share requested to regulatory authority3,000,000
Shares issued under sales agency agreements0 0

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Accumulated Other Comprehensive Loss [Abstract]
Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $3,738 and $3,822, respectively $ 14,063 $ 14,378

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss, Net of Tax (Parenthetical) (Details) - USD ($) $ in ThousandsMar. 31, 2021Dec. 31, 2020
Accumulated Other Comprehensive Loss [Abstract]
Accumulated other comprehensive income (loss), pension and other postretirement benefit plans net unamortized (gain) loss, tax $ 3,738 $ 3,822

Accumulated Other Comprehensi_5

Accumulated Other Comprehensive Loss - Reclassification out of Accumulated Other Comprehensive Income (Details) - Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] - Reclassification out of Accumulated Other Comprehensive Income [Member] - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Amortization of net prior service cost $ (200) $ (200)
Amortization of net loss3,191 3,100
Adjustment due to effects of regulation(2,592)(2,641)
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, before tax399 259
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, tax(84)(54)
Other comprehensive (income) loss, defined benefit plan, reclassification adjustment from AOCI, after tax $ 315 $ 205

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 Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Numerator:
Net income $ 68,017 $ 48,424
Denominator:
Weighted-average number of common shares outstanding-basic69,293 67,239
Effect of dilutive securities:
Performance and restricted stock awards213 142
Weighted-average number of common shares outstanding-diluted69,506 67,381
Earnings per common share:
Basic $ 0.98 $ 0.72
Diluted $ 0.98 $ 0.72

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Details) - shares3 Months Ended
Mar. 31, 2021Mar. 31, 2020
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount0 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - Damage from Fire [Member]1 Months Ended
Aug. 31, 2019USD ($)Sep. 02, 2020aBuilding
Boyds Fire [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Loss contingency, damages sought, value | $ $ 4,400,000
Labor Day Windstorm [Member]
Loss Contingencies [Line Items]
Wildfire covered area | a22,000
Number of residential, commercial and other structures impacted | Building230

Information by Business Segme_3

Information by Business Segments - Additional Information (Details)3 Months Ended
Mar. 31, 2021Reportable_Segments
Segment Reporting [Abstract]
Number of reportable segments2

Information by Business Segme_4

Information by Business Segments - Schedule of Business Segments (Details) - USD ($) $ in Thousands3 Months Ended
Mar. 31, 2021Mar. 31, 2020Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenues $ 412,870 $ 390,230
Resource costs134,579 129,547
Other operating expenses88,739 95,856
Depreciation and amortization55,348 51,656
Income (loss) from operations101,895 82,193
Interest expense26,413 26,617
Income taxes12,164 8,532
Net income (loss)68,017 48,424
Capital expenditures97,231 95,635
Total Assets6,399,496 $ 6,402,097
Operating Segments [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues412,681 389,407
Resource costs134,579 129,547
Other operating expenses87,555 94,496
Depreciation and amortization55,221 51,421
Income (loss) from operations103,017 82,780
Interest expense26,325 26,572
Income taxes12,051 8,705
Net income (loss)67,534 49,374
Capital expenditures97,203 95,526
Total Assets6,302,056 6,304,311
Operating Segments [Member] | Avista Utilities [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues399,860 377,205
Resource costs133,840 129,557
Other operating expenses84,599 91,279
Depreciation and amortization52,724 48,974
Income (loss) from operations96,693 76,534
Interest expense24,800 24,983
Income taxes10,718 7,404
Net income (loss)64,058 45,979
Capital expenditures96,394 94,056
Total Assets6,031,502 6,035,340
Operating Segments [Member] | Alaska Electric Light & Power [Member] | Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues12,821 12,202
Resource costs739 (10)
Other operating expenses2,956 3,217
Depreciation and amortization2,497 2,447
Income (loss) from operations6,324 6,246
Interest expense1,525 1,589
Income taxes1,333 1,301
Net income (loss)3,476 3,395
Capital expenditures809 1,470
Total Assets270,554 268,971
Other [Member] | Non-Utility Revenue [Member]
Segment Reporting Information [Line Items]
Operating revenues189 823
Resource costs0 0
Other operating expenses1,184 1,360
Depreciation and amortization127 235
Income (loss) from operations(1,122)(587)
Interest expense129 131
Income taxes113 (173)
Net income (loss)483 (950)
Capital expenditures28 109
Total Assets110,117 109,658
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues0 0
Resource costs0 0
Other operating expenses0 0
Depreciation and amortization0 0
Income (loss) from operations0 0
Interest expense(41)(86)
Income taxes0 0
Net income (loss)0 0
Capital expenditures0 $ 0
Total Assets $ (12,677) $ (11,872)