Avista (AVA) 10-Q 5 Aug 15 2015 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 31, 2015
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Trading Symbol	ava
Entity Registrant Name	AVISTA CORP
Entity Central Index Key	104,918
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		62,296,577

Consolidated Statements Of Inco

Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Common Stock, Dividends, Per Share, Cash Paid	$ 0.33	$ 0.3175	$ 0.66	$ 0.635
Operating Revenues:
Utility revenues	$ 330,830	$ 303,105	$ 767,237	$ 740,229
Other non-utility revenues	6,502	9,475	16,585	18,929
Total operating revenues	337,332	312,580	783,822	759,158
Utility operating expenses:
Resource costs	141,116	128,922	350,676	349,419
Other operating expenses	73,112	67,349	146,284	134,686
Depreciation and amortization	35,676	31,180	69,976	61,906
Taxes other than income taxes	23,257	21,367	53,155	49,513
Other non-utility operating expenses:
Other operating expenses	6,646	880	16,462	10,263
Depreciation and amortization	165	151	334	298
Total operating expenses	279,972	249,849	636,887	606,085
Income from operations	57,360	62,731	146,935	153,073
Interest expense	19,866	18,547	39,768	37,291
Interest expense to affiliated trusts	115	112	227	223
Public Utilities, Allowance for Funds Used During Construction, Additions	(879)	(834)	(1,796)	(1,495)
Other income-net	(1,836)	(3,055)	(4,067)	(5,655)
Income before income taxes	40,094	47,961	112,803	122,709
Income tax expense	15,016	16,691	41,263	43,973
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	25,078	31,270	71,540	78,736
Net income	25,274	100,582	71,736	149,563
Net income from discontinued operations	196	69,312	196	70,827
Net income attributable to noncontrolling interests	(28)	289	(41)	(193)
Income (Loss) from Continuing Operations Attributable to Parent	25,050	31,254	71,499	78,730
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	196	69,617	196	70,640
Net income attributable to Avista Corporation shareholders	$ 25,246	$ 100,871	$ 71,695	$ 149,370
Weighted-average common shares outstanding (thousands), basic	62,281	60,184	62,299	60,153
Weighted-average common shares outstanding (thousands), diluted	62,600	60,463	62,744	60,316
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.41	$ 0.52	$ 1.15	$ 1.31
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	1.16	0	1.17
Earnings per common share attributable to Avista Corporation shareholders:
Basic	0.41	1.68	1.15	2.48
Diluted (usd per share)	0.40	1.67	1.14	2.48
Income (Loss) from Continuing Operations, Per Diluted Share	0.40	0.52	1.14	1.31
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	$ 0	$ 1.15	$ 0	$ 1.17

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income	$ 25,274	$ 100,582	$ 71,736	$ 149,563
Other Comprehensive Income (Loss):
Unrealized investment gains/(losses) - net of taxes	0	341	0	1,126
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax			0	(2)
Other Comprehensive Loss Reclassification Adjustment From AOCI For Sale Of Securities, Net of Tax	0	462	0	462
Change in unfunded benefit obligation for pension and other postretirement benefit plans - net of taxes	245	112	491	223
Total other comprehensive loss	245	915	491	1,809
Comprehensive income	25,519	101,497	72,227	151,372
Comprehensive income attributable to noncontrolling interests	(28)	289	(41)	(193)
Comprehensive income attributable to Avista Corporation shareholders	$ 25,491	$ 101,786	$ 72,186	$ 151,179

Consolidated Statements Of Com4

Consolidated Statements Of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Unrealized investment gains - taxes	$ 0	$ 201	$ 0	$ 664
Realized investment gains - taxes	0	0	0	(1)
Other Comprehensive Loss Reclassification Adjustment From AOCI For Sale Of Securities, Tax	0	273	0	273
Change in unfunded benefit obligation for pension and other postretirement benefit plans - taxes	$ 132	$ 62	$ 264	$ 121

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 16,242	$ 22,143
Accounts and notes receivable-less allowances of $8,094 and $4,888, respectively	136,321	171,925
Utility energy commodity derivative assets	484	1,525
Regulatory asset for utility derivatives	21,464	29,640
Materials and supplies, fuel stock and natural gas stored	50,873	66,356
Deferred income taxes	19,576	14,794
Income taxes receivable	942	43,893
Other current assets	43,428	45,071
Total current assets	289,330	395,347
Net Utility Property:
Utility plant in service	4,941,008	4,718,062
Construction work in progress	174,482	227,758
Total	5,115,490	4,945,820
Less: Accumulated depreciation and amortization	1,388,790	1,325,858
Total net utility property	3,726,700	3,619,962
Other Non-current Assets:
Investment in exchange power-net	10,208	11,433
Investment in affiliated trusts	11,547	11,547
Goodwill	57,672	57,976
Long-term energy contract receivable of Spokane Energy	21,590	28,202
Other property and investments-net	42,506	42,016
Total other non-current assets	143,523	151,174
Deferred Charges:
Regulatory assets for deferred income tax	96,806	100,412
Regulatory assets for pensions and other postretirement benefits	229,684	235,758
Other regulatory assets	97,690	91,920
Regulatory Asset For Interest Rate Swap Agreements Noncurrent	51,490	77,063
Non-current regulatory asset for utility derivatives	28,214	24,483
Other deferred charges	16,552	16,212
Total deferred charges	520,436	545,848
Total assets	4,679,989	4,712,331
Current Liabilities:
Accounts payable	70,086	112,974
Current portion of long-term debt	3,162	6,424
Current portion of nonrecourse long-term debt of Spokane Energy	0	1,431
Short-term borrowings	90,000	105,000
Utility energy commodity derivative liabilities	12,681	18,045
Other current liabilities	131,017	141,395
Total current liabilities	306,946	385,269
Long-term debt	1,494,885	1,492,062
Long-term debt to affiliated trusts	51,547	51,547
Regulatory liability for utility plant retirement costs	259,006	254,140
Pensions and other postretirement benefits	188,862	189,489
Deferred income taxes	718,265	710,342
Other non-current liabilities and deferred credits	146,473	146,240
Total liabilities	$ 3,165,984	$ 3,229,089
Commitments and Contingencies (See Notes to Consolidated Financial Statements)
Avista Corporation Stockholders’ Equity:
Common stock, no par value; 200,000,000 shares authorized; 62,293,936 and 62,243,374 shares outstanding	$ 1,001,253	$ 999,960
Accumulated other comprehensive loss	(7,397)	(7,888)
Retained earnings	520,537	491,599
Total Avista Corporation stockholders’ equity	1,514,393	1,483,671
Noncontrolling Interests	(388)	(429)
Total equity	1,514,005	1,483,242
Total liabilities and equity	$ 4,679,989	$ 4,712,331

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Accounts and notes receivable, allowances	$ 8,094	$ 4,888
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares outstanding	62,293,936	60,076,752

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating Activities:
Net income	$ 71,736	$ 149,563
Non-cash items included in net income:
Depreciation and amortization	72,131	68,543
Provision for deferred income taxes	6,161	24,161
Power and natural gas cost amortizations (deferrals), net	11,414	(10,032)
Amortization of debt expense	1,774	1,889
Amortization of investment in exchange power	1,225	1,225
Stock-based compensation expense	3,441	4,838
Equity-related AFUDC	(3,874)	(4,237)
Pension and other postretirement benefit expense	18,786	11,585
Amortization of Spokane Energy contract	6,612	6,078
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	(163)	(161,100)
Other	(5,216)	8,778
Contributions to defined benefit pension plan	(8,000)	(21,500)
Changes in working capital components:
Accounts and notes receivable	25,460	59,086
Materials and supplies, fuel stock and natural gas stored	15,484	(4,491)
Increase (Decrease) in Deposit Assets	(908)	9,753
Increase (Decrease) in Income Taxes Receivable	42,951	7,783
Other current assets	2,609	(5,273)
Accounts payable	(26,396)	(34,025)
Increase (Decrease) in Income Taxes Payable	1,055	97,617
Other current liabilities	(4,170)	13,747
Net cash provided by operating activities	232,112	223,988
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(177,752)	(136,514)
Other capital expenditures	(504)	(6,122)
Federal grant payments received	2,538	1,729
Payments to Acquire Businesses, Net of Cash Acquired	(95)	(4,697)
Decrease (increase) In Money Market Funds Held For Clients	0	(18,931)
Payments to Acquire Available-for-sale Securities	0	(12,267)
Sale and maturity of securities available for sale	0	14,612
Proceeds from Divestiture of Businesses, Net of Cash Divested	1,022	229,903
Other	(798)	(475)
Net cash provided by (used in) investing activities	(175,589)	67,238
Financing Activities:
Net decrease in short-term borrowings	(15,000)	(19,500)
Repayment of borrowings from Ecova line of credit	0	(46,000)
Redemption and maturity of long-term debt	(1,414)	(149)
Maturity of nonrecourse long-term debt of Spokane Energy	(1,431)	(8,026)
Issuance of common stock	1,080	1,980
Payments for Repurchase of Common Stock	(2,920)	0
Cash dividends paid	(41,268)	(38,327)
Increase in client fund obligations	0	16,216
Payments to Noncontrolling Interests	0	(54,179)
Payments for Repurchase of Redeemable Noncontrolling Interest	0	(20,871)
Other	(1,471)	3,023
Net cash used in financing activities	(62,424)	(165,833)
Net increase (decrease) in cash and cash equivalents	(5,901)	125,393
Cash and cash equivalents at beginning of period	22,143	82,574
Cash and cash equivalents at end of period	$ 16,242	$ 207,967

Consolidated Statements Of Equi

Consolidated Statements Of Equity And Redeemable Noncontrolling Interests - USD ($) $ in Thousands	Total	Common Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Noncontrolling Interests [Member]	Redeemable Noncontrolling Interests [Member]
Excess Tax Benefit from Share-based Compensation, Financing Activities		$ 3,936
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Redeemable						$ (4)
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable					$ 197
Noncontrolling Interest, Decrease from Deconsolidation	$ (23,612)
Beginning Balance (in shares) at Dec. 31, 2013		60,076,752
Issuance of common stock		143,347
Beginning Balance at Dec. 31, 2013		$ 896,993	$ (5,819)	$ 407,092	20,001	15,889
Equity compensation expense		4,765
Issuance of common stock, net of issuance costs		1,980
Adjustments Related to Tax Withholding for Share-based Compensation		0
Stock Repurchased During Period, Value		0		0
Equity transactions of consolidated subsidiaries		(1,062)
Payments for Repurchase of Redeemable Noncontrolling Interest	(20,871)	(20,871)
Other comprehensive loss	1,809		1,809
Net income attributable to Avista Corporation shareholders	149,370			149,370
Cash dividends paid (common stock)				(38,327)
Other					2,943
Purchase of subsidiary noncontrolling interests						(12)
Valuation adjustments and other noncontrolling interests activity				10,150		(15,873)
Ending Balance at Jun. 30, 2014	1,410,016	$ 885,741	(4,010)	528,285	(471)	0
Ending Balance (in shares) at Jun. 30, 2014		60,220,099
Stock Repurchased During Period, Shares		0
Total equity	1,409,545
Total equity	1,483,242
Excess Tax Benefit from Share-based Compensation, Financing Activities		$ 43
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Redeemable						0
Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable					41
Noncontrolling Interest, Decrease from Deconsolidation	$ 0
Beginning Balance (in shares) at Dec. 31, 2014	60,076,752	62,243,374
Issuance of common stock		139,962
Beginning Balance at Dec. 31, 2014	$ 1,483,671	$ 999,960	(7,888)	491,599	(429)	0
Equity compensation expense		3,081
Issuance of common stock, net of issuance costs		1,080
Adjustments Related to Tax Withholding for Share-based Compensation		(1,480)
Stock Repurchased During Period, Value		(1,431)		(1,489)
Equity transactions of consolidated subsidiaries		0
Payments for Repurchase of Redeemable Noncontrolling Interest	0	0
Other comprehensive loss	491		491
Net income attributable to Avista Corporation shareholders	71,695			71,695
Cash dividends paid (common stock)				(41,268)
Other					0
Purchase of subsidiary noncontrolling interests						0
Valuation adjustments and other noncontrolling interests activity				0		0
Ending Balance at Jun. 30, 2015	$ 1,514,393	$ 1,001,253	$ (7,397)	$ 520,537	$ (388)	$ 0
Ending Balance (in shares) at Jun. 30, 2015	62,293,936	62,293,936
Stock Repurchased During Period, Shares	(89,400)	(89,400)
Total equity	$ 1,514,005

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	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 the 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 Avista Utilities' Noxon Rapids generating facility. On July 1, 2014, Avista Corp. acquired Alaska Energy and Resources Company (AERC), and as of that date, AERC is a wholly-owned subsidiary of Avista Corp. The primary subsidiary of AERC is Alaska Electric Light and Power Company (AEL&P), comprising the regulated utility operations in Alaska. There are no AERC earnings included in the overall results of Avista Corp. in the first half of 2014. See Note 3 for information regarding the acquisition of AERC. Avista Capital, Inc. (Avista Capital), a wholly owned subsidiary of Avista Corp., is the parent company of all of the subsidiary companies in the non-utility businesses, except Spokane Energy, LLC (Spokane Energy). During the first half of 2014, Avista Capital’s subsidiaries included Ecova, Inc. (Ecova), which was an 80.2 percent owned subsidiary prior to its disposition on June 30, 2014. Ecova was a provider of energy efficiency and other facility information and cost management programs and services for multi-site customers and utilities throughout North America. See Note 4 for information regarding the disposition of Ecova and Note 14 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. Ecova's revenues and expenses are included in the Condensed Consolidated Statements of Income in discontinued operations; however, as of June 30, 2014 and for all subsequent reporting periods there are no balance sheet amounts included for Ecova. All tables throughout the Notes to Condensed Consolidated Financial Statements that present Condensed Consolidated Statements of Income information were revised to include only the amounts from continuing operations. 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. Taxes Other Than Income Taxes Taxes other than income taxes include state excise taxes, city occupational and franchise taxes, real and personal property taxes and certain other taxes not based on net income. These taxes are generally based on revenues or the value of property. Utility related taxes collected from customers (primarily state excise taxes and city utility taxes) are recorded as operating revenue and expense and totaled the following amounts for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Utility taxes $ 12,941 $ 12,469 $ 32,439 $ 32,207 Other Income-Net Other income-net consisted of the following items for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Interest income $ 117 $ 250 $ 360 $ 524 Interest income on regulatory deferrals 14 51 34 95 Equity-related AFUDC 1,659 2,203 3,874 4,237 Net gain (loss) on investments (67 ) 185 (451 ) 145 Other income 113 366 250 654 Total $ 1,836 $ 3,055 $ 4,067 $ 5,655 Materials and Supplies, Fuel Stock and Natural Gas Stored Inventories of materials and supplies, fuel stock and natural gas stored 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 June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Materials and supplies $ 35,056 $ 32,483 Fuel stock 5,714 5,142 Natural gas stored 10,103 28,731 Total $ 50,873 $ 66,356 Investments and Funds Held for Clients and Client Fund Obligations In connection with its bill paying services, Ecova collected funds from its clients and remitted the funds to the appropriate utility or other service provider. Some of the funds collected were invested by Ecova and classified as investments and funds held for clients, and a related liability for client fund obligations was recorded. Investments and funds held for clients included cash and cash equivalent investments, money market funds and investment securities classified as available for sale. Ecova did not invest the funds directly for the clients' benefit; therefore, Ecova bore the risk of loss associated with the investments. As of June 30, 2014 and for all subsequent reporting periods there are no longer any investments and funds held for clients due to the disposition of Ecova. The following is a summary of the disposition of available-for-sale securities for the three and six months ended June 30 , 2014 (dollars in thousands): Three months ended June 30, 2014 Six months ended June 30, 2014 Proceeds from sales, maturities and calls $ 3,209 $ 14,612 Gross realized gains — 3 Gross realized losses (1) (735 ) (735 ) (1) The gross realized losses for both the three and six months ended June 30, 2014 were included in the determination of the gain on the disposition of Ecova and were not the result of selling any individual securities. Derivative Assets and Liabilities Derivatives are recorded as either assets or liabilities on the Condensed Consolidated Balance Sheets measured at estimated fair value. In certain defined conditions, a derivative may be specifically designated as a hedge for a particular exposure. The accounting for a derivative depends on the intended use of such derivative and the resulting designation. The Washington Utilities and Transportation Commission (UTC) and the Idaho Public Utilities Commission (IPUC) issued accounting orders authorizing Avista Utilities 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. The orders provide for Avista Utilities to not recognize the unrealized gain or loss on utility derivative commodity instruments in the Condensed Consolidated Statements of Income. Realized gains or losses are recognized in the periods of delivery, subject to approval for recovery through retail rates. Realized gains and losses, subject to regulatory approval, result in adjustments to retail rates through purchased gas cost adjustments, the Energy Recovery Mechanism (ERM) in Washington, the Power Cost Adjustment (PCA) mechanism in Idaho, and periodic general rates cases. Regulatory assets are assessed regularly and are probable for 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 agreements, each period Avista Utilities records all mark-to-market gains and losses as assets and liabilities and records offsetting regulatory assets and liabilities, such that there is no income statement impact. Upon settlement of interest rate swaps, the regulatory asset or liability (included as part of long-term debt) is amortized as a component of interest expense over the term of the associated debt. Fair Value Measurements Fair value represents the price that would be received to sell 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 swap agreements 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. Regulatory Deferred Charges and Credits The Company follows the accounting practices for regulated operations for its regulated utility businesses because: • rates for regulated services are established by or subject to approval by independent third-party regulators, • the regulated rates are designed to recover the cost of providing the regulated services, and • in view of demand for the regulated services and the level of competition, it is reasonable to assume that rates can be charged to and collected from customers at levels that will recover costs. Regulatory accounting practices require that certain costs and/or obligations (such as incurred power and natural gas costs not currently included in rates, but expected to be recovered or refunded in the future) are reflected as deferred charges or credits on the Condensed Consolidated Balance Sheets. These costs and/or obligations are not reflected in the Condensed Consolidated Statements of Income until the period during which matching revenues are recognized. The Company also has decoupling revenue deferrals. As opposed to cost deferrals which are not recognized in the Condensed Consolidated Statements of Income until they are included in rates, decoupling revenue is recognized in the Condensed Consolidated Statements of Income during the period it occurs (i.e. during the period of revenue shortfall or excess due to fluctuations in customer usage) and a regulatory asset/liability is established which will be surcharged or rebated to customers in future periods. If at some point in the future the Company determines that it no longer meets the criteria for continued application of regulatory accounting practices for all or a portion of its regulated operations, the Company could be: • required to write off its regulatory assets, • precluded from the future deferral of costs or decoupled revenues not recovered through rates at the time such amounts are incurred, even if the Company expected to recover these amounts from customers in the future. Accumulated Other Comprehensive Loss Accumulated other comprehensive loss, net of tax, consisted of the following as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $(3,983) and $(4,247), respectively $ (7,397 ) $ (7,888 ) The following table details the reclassifications out of accumulated other comprehensive loss by component for the three and six months ended June 30 (dollars in thousands). Items in parenthesis indicate reductions to net income. Amounts Reclassified from Accumulated Other Comprehensive Loss Three months ended June 30, Six months ended June 30, Details about Accumulated Other Comprehensive Loss Components 2015 2014 2015 2014 Affected Line Item in Statement of Income Realized gains on investment securities $ — $ — $ — $ 3 (a) Realized losses on investment securities — (735 ) — (735 ) (a) — (735 ) — (732 ) Total before tax — 273 — 272 Tax expense (a) $ — $ (462 ) $ — $ (460 ) Net of tax Amortization of defined benefit pension items Amortization of net prior service cost $ 273 $ 38 $ 546 $ 76 (b) Amortization of net loss (3,687 ) (1,990 ) $ (7,375 ) $ (3,980 ) (b) Adjustment due to effects of regulation 3,037 1,778 6,074 3,560 (b) (377 ) (174 ) (755 ) (344 ) Total before tax 132 62 264 121 Tax benefit $ (245 ) $ (112 ) $ (491 ) $ (223 ) Net of tax (a) These amounts were included as part of net income from discontinued operations (see Note 4 for additional details). (b) These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 7 for additional details). Appropriated Retained Earnings In accordance with the hydroelectric licensing requirements of section 10(d) of the Federal Power Act (FPA), the Company maintains an appropriated retained earnings account for any earnings in excess of the specified rate of return on the Company's investment in the licenses for its various hydroelectric projects. The rate of return on investment is specified in the various hydroelectric licensing agreements for the Clark Fork River and Spokane River. Per section 10(d) of the FPA, the Company must maintain these excess earnings in an appropriated retained earnings account until the termination of the licensing agreements or apply them to reduce the net investment in the licenses of the hydroelectric projects at the discretion of the FERC. The Company typically calculates the earnings in excess of the specified rate of return on an annual basis, usually during the second quarter. In addition to the hydroelectric project licenses identified above for Avista Utilities, the requirements of section 10(d) of the FPA also apply to the AEL&P licenses for Lake Dorothy and Annex Creek/Salmon Creek (combined). The appropriated retained earnings amounts included in retained earnings were as follows as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Appropriated retained earnings $ 21,030 $ 14,270 Dividends The payment of dividends on common stock could be limited by: • certain covenants applicable to preferred stock (when outstanding) contained in the Company’s Restated Articles of Incorporation, as amended (currently there are no preferred shares outstanding), • certain covenants applicable to the Company's outstanding long-term debt and committed line of credit agreements, • the hydroelectric licensing requirements of section 10(d) of the FPA, and • certain requirements under the Public Utility Commission of Oregon (OPUC) approval of the AERC acquisition. After July 1, 2015 (one year following the acquisition date), the OPUC does not permit one-time or special dividends from AERC to Avista Corp. and does not permit Avista Utilities' total equity to total capitalization to be less than 40 percent , without approval from the OPUC. However, the OPUC approval does allow for regular distributions of AERC earnings to Avista Corp. as long as AERC remains sufficiently capitalized and insured. Under the covenant applicable to the Company's committed line of credit agreement, which does not permit the ratio of “consolidated total debt” to “consolidated total capitalization” to be greater than 65 percent at any time, the amount of retained earnings available for dividends at June 30, 2015 was limited to approximately $410.5 million . Under the requirements of the OPUC approval of the AERC acquisition as outlined above, the amount available for dividends at June 30, 2015 was limited to approximately $272.0 million . Stock Repurchase Program On December 16, 2014, the Company announced that Avista Corp.'s Board of Directors approved the repurchase of up to 800,000 shares of the Company’s outstanding common stock, commencing on January 2, 2015, and expiring on March 31, 2015 (first quarter 2015 program). The number of shares repurchased through the first quarter 2015 program were in addition to the number of shares repurchased during 2014 under a separate stock repurchase program, which expired on December 31, 2014. The parameters of the first quarter 2015 program were consistent with the parameters of the 2014 program. Under the first quarter 2015 program, the Company repurchased 89,400 shares at a total cost of $2.9 million and an average cost of $32.66 per share. All repurchased shares reverted to the status of authorized but unissued shares. 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 losses that do not meet these conditions for accrual, if there is a reasonable possibility that a loss may be incurred. As of June 30, 2015 , the Company has not recorded any significant amounts related to unresolved contingencies. Reclassifications Certain prior year amounts on the Company's Condensed Consolidated Statements of Cash Flows were reclassified to conform to the current year presentation. In the current year Condensed Consolidated Statements of Cash Flows, "Decrease (increase) in collateral posted for derivative instruments," and "Income taxes receivable," were added as their own line items. These were previously included in "Other current assets" in the operating activities section.

New Accounting Standards

New Accounting Standards	6 Months Ended
	Jun. 30, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Standards	NEW ACCOUNTING STANDARDS In April 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2014-08, "Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity." This ASU amends the definition of a discontinued operation and requires entities to provide additional disclosures about discontinued operations as well as disposal transactions that do not meet the discontinued-operations criteria. ASU 2014-08 makes it more difficult for a disposal transaction to qualify as a discontinued operation. In addition, the ASU requires entities to reclassify assets and liabilities of a discontinued operation for all comparative periods presented in the Balance Sheet rather than just the current period and it requires additional disclosures on the face of the Statement of Cash Flows regarding discontinued operations. This ASU became effective for periods beginning on or after December 15, 2014; however, early adoption was permitted. The Company evaluated this standard and determined that it would not early adopt this standard. Since the disposition of Ecova occurred before the effective date of this standard, and the Company did not early adopt this standard, there is no impact on the Company's financial condition, results of operations and cash flows in the current year. In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers (Topic 606)," which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The core principle of the revenue model is that an entity identifies the various performance obligations in a contract, allocates the transaction price among the performance obligations and recognizes revenue as the entity satisfies the performance obligations. This ASU was originally effective for periods beginning after December 15, 2016 and early adoption is not permitted. In July 2015, the FASB voted to defer the effective date for one year, with adoption as of the original date permitted. However, while this ASU is not effective until 2018, it will require retroactive application to all periods presented in the financial statements. As such, at adoption in 2018, amounts in 2016 and 2017 may have to be revised or a cumulative adjustment to opening retained earnings may have to be recorded. The Company is evaluating this standard and cannot, at this time, estimate the potential impact on its future financial condition, results of operations and cash flows. In February 2015, the FASB issued ASU No. 2015-02, "Consolidation (Topic 810): Amendments to the Consolidation Analysis." This ASU significantly changes the consolidation analysis required under GAAP, including the identification of variable interest entities (VIE). The ASU also removes the deferral of the VIE analysis related to investments in certain investment funds, which will result in a different consolidation evaluation for these types of investments. This ASU is effective for periods beginning on or after December 15, 2015; however, early adoption is permitted. The Company evaluated this standard and determined that it will not early adopt this standard. The Company is evaluating this standard and cannot, at this time, estimate the potential impact on its future financial condition, results of operations and cash flows. In April 2015, the FASB issued ASU No. 2015-03, "Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs." This ASU amends the presentation of debt issuance costs in the financial statements such that an entity presents such costs in the balance sheet as a direct deduction from the related debt liability rather than as a deferred asset. Amortization of the costs will continue to be reported as interest expense. This ASU is effective for periods beginning on or after December 15, 2015; however, early adoption is permitted. Upon adoption, entities will apply the new guidance retrospectively to all comparable prior periods presented in the financial statements. The Company evaluated this standard during the first quarter of 2015 and determined that it would not early adopt this standard. Upon adoption, the Company will revise its current presentation of debt issuance costs in the Condensed Consolidated Balance Sheets; however, the Company does not expect a material impact on its future financial condition, results of operations or cash flows as a result of the adoption. In April 2015, the FASB issued ASU No. 2015-05, "Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement." This ASU provides guidance on how organizations should account for fees paid in a cloud computing arrangement, including helping organizations understand whether their arrangement includes a software license. If the arrangement includes a software license, the software license would be accounted for in a manner consistent with internal-use software. If a cloud-computing arrangement does not include a software license, the customer is required to account for the arrangement as a service contract. This ASU is effective for periods beginning on or after December 15, 2015; however, early adoption is permitted. The Company evaluated this standard and determined that it will not early adopt this standard. Upon adoption, an entity can elect to apply this ASU prospectively or retroactively and disclose the method selected. The Company is evaluating this standard and cannot, at this time, estimate the potential impact on its future financial condition, results of operations and cash flows. In July 2015, the FASB issued ASU No. 2015-11, "Inventory (Topic 330): Simplifying the Measurement of Inventory." This ASU simplifies the inventory measurement guidance by removing the requirement to measure inventory at the lower of cost or market and instead requires inventory to be measured at the lower of cost or net realizable value (estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation). This ASU applies to all inventory except that which is measured using last-in, first-out (LIFO) or the retail inventory method. Inventory measured using first-in, first-out (FIFO) or average cost is included in the new amendment. This ASU is effective for periods beginning on or after December 15, 2016. The new guidance shall be applied prospectively, and earlier application is permitted as of the beginning of an interim or annual reporting period. The Company is evaluating this standard and cannot, at this time, estimate the potential impact on its future financial condition, results of operations and cash flows. However, the Company does not expect to early adopt this standard. In May 2015, the FASB issued ASU No. 2015-07, "Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent)." This ASU removes, from the fair value hierarchy, investments for which the practical expedient is used to measure fair value at net asset value (NAV). Instead, an entity is required to include those investments as a reconciling line item so that the total fair value amount of investments in the disclosure is consistent with the amount on the balance sheet. Further, entities must provide certain disclosures for investments for which they elect to use the NAV practical expedient to determine fair value. This ASU is effective for periods beginning on or after December 15, 2015 and early adoption is permitted. Upon adoption, this ASU should be applied retrospectively to all periods presented. The Company is evaluating this standard and cannot, at this time, estimate the potential impact on its future financial condition, results of operations and cash flows.

Business Acquisitions

Business Acquisitions	6 Months Ended
	Jun. 30, 2015
Business Combinations [Abstract]
Business Combination Disclosure	BUSINESS ACQUISITIONS Alaska Energy and Resources Company On July 1, 2014, the Company acquired AERC, based in Juneau, Alaska, and as of that date, AERC became a wholly-owned subsidiary of Avista Corp. The primary subsidiary of AERC is AEL&P, a regulated utility which provides electric services to 16,552 customers in the City and Borough of Juneau (CBJ), Alaska. In addition to the regulated utility, AERC owns AJT Mining, which is an inactive mining company holding certain properties. The purpose of the acquisition was to expand and diversify Avista Corp.'s energy assets and deliver long-term value to its customers, communities and investors. In connection with the closing, on July 1, 2014 Avista Corp. issued 4,500,014 new shares of common stock to the shareholders of AERC based on a contractual formula that resulted in a price of $32.46 per share, reflecting a purchase price of $170.0 million , plus acquired cash, less outstanding debt and other closing adjustments. The $32.46 price per share of Avista Corp. common stock was determined based on the average closing stock price of Avista Corp. common stock for the 10 consecutive trading days immediately preceding, but not including, the trading day prior to July 1, 2014. This value was used solely for determining the number of shares to issue based on the adjusted contract closing price (see reconciliation below). The fair value of the consideration transferred at the closing date was based on the closing stock price of Avista Corp. common stock on July 1, 2014, which was $33.35 per share. On October 1, 2014, a working capital adjustment was made in accordance with the agreement and plan of merger which resulted in Avista Corp. issuing an additional 1,427 shares of common stock to the shareholders of AERC. The number of shares issued on October 1, 2014 was based on the same contractual formula described above. The fair value of the new shares issued in October was $30.71 per share, which was the closing stock price of Avista Corp. common stock on that date. The contract acquisition price and the fair value of consideration transferred for AERC were as follows (in thousands, except "per share" and number of shares data): Contract acquisition price (using the calculated $32.46 per share common stock price) Gross contract price $ 170,000 Acquired cash 19,704 Acquired debt (excluding capital lease obligation) (38,832 ) Other closing adjustments (58 ) Total adjusted contract price $ 150,814 Fair value of consideration transferred Avista Corp. common stock (4,500,014 shares at $33.35 per share) $ 150,075 Avista Corp. common stock (1,427 shares at $30.71 per share) 44 Cash 4,792 Fair value of total consideration transferred $ 154,911 During the second quarter of 2015, the Company recorded a reduction to goodwill of approximately $0.3 million due to income tax related adjustments. After consideration of the goodwill adjustment in the second quarter of 2015, the transaction resulted in a total amount of goodwill of $52.4 million . The goodwill associated with this acquisition is not deductible for tax purposes. The remainder of the assets acquired and liabilities assumed have not changed from the amounts disclosed in the 2014 Form 10-K. The majority of AERC’s operations are subject to the rate-setting authority of the Regulatory Commission of Alaska (RCA) and are accounted for pursuant to GAAP, including the accounting guidance for regulated operations. The rate-setting and cost recovery provisions currently in place for AERC’s regulated operations provide revenues derived from costs, including a return on investment, of assets and liabilities included in rate base. Due to this regulation, the fair values of AERC’s assets and liabilities subject to these rate-setting provisions are assumed to approximate their carrying values. There were not any identifiable intangible assets associated with this acquisition. The excess of the purchase consideration over the estimated fair values of the assets acquired and liabilities assumed was recognized as goodwill at the acquisition date. The goodwill reflects the value paid for the expected continued growth of a rate-regulated business located in a defined service area with a constructive regulatory environment, the attractiveness of stable, growing cash flows, as well as providing a platform for potential future growth outside of the rate-regulated electric utility in Alaska, as well as potential additional utility investment. The following table summarizes the supplemental pro forma information for the three and six months ended June 30 , 2014 compared to actual 2015 information related to the acquisition of AERC as if the acquisition had occurred on January 1, 2013 (dollars in thousands - unaudited): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Actual Pro forma Actual Pro forma Actual Avista Corp. revenues from continuing operations (excluding AERC) $ 327,085 $ 312,580 $ 760,784 $ 759,158 Supplemental pro forma AERC revenues (1) 10,247 11,782 23,038 24,546 Total pro forma revenues 337,332 324,362 783,822 783,704 Actual AERC revenues included in Avista Corp. revenues (1) 10,247 — 23,038 — Actual Avista Corp. net income from continuing operations attributable to Avista Corp. shareholders (excluding AERC) 24,222 31,254 68,140 78,730 Actual Avista Corp. net income from discontinued operations attributable to Avista Corp. shareholders 196 69,617 196 70,640 Adjustment to Avista Corp.'s net income for acquisition costs (net of tax) (2) 16 219 21 672 Supplemental pro forma AERC net income (1) 828 2,371 3,359 5,627 Total pro forma net income 25,262 103,461 71,716 155,669 Actual AERC net income included in Avista Corp. net income (1) $ 828 $ — $ 3,359 $ — (1) AERC was acquired on July 1, 2014; therefore, none of the supplemental revenues and net income for the three and six months ended June 30 , 2014 were included in the actual results of Avista Corp. for those periods. The amounts disclosed for the three and six months ended June 30 , 2015 were included in the overall results of Avista Corp. (2) This adjustment is to treat all transaction costs as if they occurred on January 1, 2013 and to remove them from the periods in which they actually occurred. The transaction costs were expensed and presented in the Condensed Consolidated Statements of Income in other operating expenses within utility operating expenses. Since the start of the transaction through June 30, 2015 , Avista Corp. has expensed $3.0 million (pre-tax) in total transaction fees. In addition to the amounts expensed, through June 30, 2015 , Avista Corp. has included $0.4 million in fees associated with the issuance of common stock for the transaction as a reduction to common stock. These fees do not impact the supplemental pro forma information above.

Discontinued Operations Discont

Discontinued Operations Discontinued Operations (Notes)	6 Months Ended
	Jun. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure	DISCONTINUED OPERATIONS On June 30, 2014, Avista Capital, the non-regulated subsidiary of Avista Corp., completed the sale of its interest in Ecova to Cofely USA Inc., an indirect subsidiary of GDF SUEZ, a French multinational utility company, and an unrelated party to Avista Corp. The sale price was $335.0 million in cash, less the payment of debt and other customary closing adjustments. At the closing of the transaction on June 30, 2014, Ecova became a wholly-owned subsidiary of Cofely USA Inc. and the Company has not had and will not have any further involvement with Ecova after such date. The purchase price of $335.0 million , as adjusted, was divided among the security holders of Ecova, including minority shareholders and option holders, pro rata based on ownership. Approximately $16.8 million ( 5 percent of the purchase price) will be held in escrow for 15 months from the closing of the transaction to satisfy certain indemnification obligations under the merger agreement. An additional $1.0 million was held in escrow pending resolution of adjustments to working capital and this escrow for the working capital adjustment was resolved in the second quarter of 2015. Avista Capital and Cofely USA Inc. agreed to make an election under Section 338(h)(10) of the Internal Revenue Code (Code) of 1986, as amended, with respect to the purchase and sale of Ecova to allocate the merger consideration among the assets of Ecova deemed to have been acquired in the merger. When all escrow amounts are released, the sales transaction is expected to provide cash proceeds to Avista Corp., net of debt, payment to option and minority holders, income taxes and transaction expenses, of $143.7 million and result in a net gain of $69.9 million (which was mostly recognized during the second quarter of 2014 and had some insignificant true-ups during the third and fourth quarters of 2014 and the second quarter of 2015). The Company expects to receive the full amount of its portion of the remaining escrow accounts; therefore, these amounts were included in the gain calculation. Prior to the completion of the sale, Ecova was a reportable business segment. Amounts reported in discontinued operations for 2014 relate solely to the Ecova business segment. The following table presents amounts that were included in discontinued operations for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Revenues $ — $ 43,150 $ — $ 87,534 Gain on sale of Ecova (1) 163 161,100 163 161,100 Transaction expenses and accelerated employee benefits (2) — 8,976 — 8,976 Gain on sale of Ecova, net of transaction expenses 163 152,124 163 152,124 Income before income taxes 163 154,190 163 156,599 Income tax expense (benefit) (3) (33 ) 84,878 (33 ) 85,772 Net income from discontinued operations 196 69,312 196 70,827 Net income attributable to noncontrolling interests — 305 — (187 ) Net income from discontinued operations attributable to Avista Corp. shareholders $ 196 $ 69,617 $ 196 $ 70,640 (1) The gain recognized during the second quarter of 2015 related to the resolution of the working capital adjustment and the release of the associated escrow funds. (2) Avista Corp.'s portion of the total transaction expenses was $9.1 million (including amounts which were withheld from the transaction net proceeds) and this was recognized during the second and third quarters of 2014. All transaction expenses paid on the Ecova sale (including Avista Corp.'s portion and the portion attributable to the minority interest holders of Ecova) were $11.0 million , and of this amount, $5.4 million was withheld from the net proceeds and the remainder was paid during the second and third quarters of 2014. The transaction expenses were for legal, accounting and other consulting fees and the accelerated employee benefits related to employee stock options which were settled in accordance with the Ecova equity plan. (3) The tax benefit in the second quarter of 2015 resulted from a state tax true-up, partially offset by tax expense associated with the gain on sale recognized during the second quarter of 2015.

Derivatives And Risk Management

Derivatives And Risk Management	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedges, Assets [Abstract]
Derivatives And Risk Management	DERIVATIVES AND RISK MANAGEMENT The below disclosures in Note 5 apply only to Avista Corp. and Avista Utilities; AERC and its primary subsidiary AEL&P do not enter into derivative instruments. Energy Commodity Derivatives Avista Utilities 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 Utilities utilizes derivative instruments, such as forwards, futures, swaps and options in order to manage the various risks relating to these commodity price exposures. The Company has an energy resources risk policy and control procedures to manage these risks. The Company’s Risk Management Committee establishes the Company’s energy resources risk policy and monitors compliance. The Risk Management Committee is comprised of certain Company officers and other members of management. The Audit Committee of the Company’s Board of Directors periodically reviews and discusses enterprise risk management processes, and it focuses on the Company’s material financial and accounting risk exposures and the steps management has undertaken to control them. As part of the Company's resource procurement and management operations in the electric business, the Company engages in an ongoing process of resource optimization, which involves the economic selection from available energy resources to serve the Company's load obligations and the use of these resources to capture available economic value. The Company transacts in wholesale markets by selling and purchasing 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 the related financial risks. These transactions range from terms of intra-hour up to multiple years. Avista Utilities makes continuing projections of: • electric loads at various points in time (ranging from intra-hour to multiple years) based on, among other things, estimates of customer usage and weather, historical data and contract terms, and • resource availability at these points in time based on, among other things, fuel choices and fuel markets, estimates of streamflows, availability of generating units, historic and forward market information, contract terms, and experience. On the basis of these projections, the Company makes purchases and sales of electric capacity and energy, fuel for electric generation, and related derivative instruments to match expected resources to expected electric load requirements and reduce exposure to electricity (or fuel) market price changes. Resource optimization involves generating plant dispatch and scheduling available resources and also includes transactions such as: • purchasing fuel for generation, • when economical, selling fuel and substituting wholesale electric purchases, and • other wholesale transactions to capture the value of generation and transmission resources and fuel delivery capacity contracts. Avista Utilities’ optimization process includes entering into hedging transactions to manage risks. Transactions include both physical energy contracts and related derivative financial instruments. As part of its resource procurement and management of its natural gas business, Avista Utilities 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 Utilities’ distribution system. However, daily variations in natural gas demand can be significantly different than monthly demand projections. On the basis of these projections, Avista Utilities 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 four natural gas operating years (November through October) into the future. Avista Utilities also leaves a significant portion of its natural gas supply requirements unhedged for purchase in short-term and spot markets. Natural gas resource optimization activities include: • wholesale market sales of surplus natural gas supplies, • optimization of interstate pipeline transportation capacity not needed to serve daily load, and • purchases and sales of natural gas to optimize use of storage capacity. The following table presents the underlying energy commodity derivative volumes as of June 30, 2015 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) Financial (1) Physical (1) Financial (1) 2015 165 1,391 10,559 95,498 152 2,177 1,730 66,515 2016 394 1,348 2,505 97,058 287 2,116 1,370 74,668 2017 397 — 675 33,913 286 483 1,360 17,403 2018 397 — — 6,795 286 — 1,360 — 2019 235 — — 4,050 158 — 1,345 — Thereafter — — — — — — 2,470 — (1) Physical transactions represent commodity transactions in which Avista Utilities will take or make delivery of either electricity or natural gas; financial transactions represent derivative instruments with delivery of cash in the amount of gain or loss but with no physical delivery of the commodity, such as futures, swaps, 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 delivered and will be included in the various 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 Contracts A significant portion of Avista Utilities’ 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 Utilities’ short-term natural gas transactions and long-term Canadian transportation contracts are committed based on Canadian currency prices and settled within 60 days with U.S. dollars. Avista Utilities hedges a portion of the foreign currency risk by purchasing Canadian currency contracts when such commodity transactions are initiated. This risk has not had a material effect on the Company’s financial condition, results of operations or cash flows and these differences in cost related to currency fluctuations were included with natural gas supply costs for ratemaking. The following table summarizes the foreign currency hedges that the Company has outstanding as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Number of contracts 26 18 Notional amount (in United States currency) $ 8,183 $ 5,474 Notional amount (in Canadian currency) 10,130 6,198 Interest Rate Swap Agreements Avista Corp. is affected by fluctuating interest rates related to a portion of its existing debt and future borrowing requirements. The Finance Committee of the Board of Directors periodically reviews and discusses interest rate risk management processes and focuses on the steps management has undertaken to manage it. The Risk Management Committee also reviews the interest risk management plan. Avista Corp. manages interest rate exposure by limiting the variable rate exposures to a percentage of total capitalization. Additionally, interest rate risk is managed by monitoring market conditions when timing the issuance of long-term debt and optional debt redemptions and through the use of fixed rate long-term debt with varying maturities. The Company also hedges a portion of its interest rate risk with financial derivative instruments, which may include interest rate swaps and U.S. Treasury lock agreements. These interest rate swaps 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 interest rate swaps that the Company has entered into as of June 30, 2015 and December 31, 2014 (dollars in thousands): Balance Sheet Date Number of Contracts Notional Amount Mandatory Cash Settlement Date June 30, 2015 5 75,000 2015 6 115,000 2016 3 45,000 2017 11 245,000 2018 1 20,000 2019 December 31, 2014 5 75,000 2015 5 95,000 2016 3 45,000 2017 9 205,000 2018 Upon settlement of interest rate swaps, the regulatory asset or liability (included as part of long-term debt) is amortized as a component of interest expense over the term of the associated debt. The fair value of outstanding interest rate swaps can vary significantly from period to period depending on the total notional amount of swaps outstanding and fluctuations in market interest rates compared to the interest rates fixed by the swaps. The Company would be required to make cash payments to settle the interest rate swaps if the fixed rates are higher than prevailing market rates at the date of settlement. Conversely, the Company receives cash to settle its interest rate swaps when prevailing market rates at the time of settlement exceed the fixed swap rates. Summary of Outstanding Derivative Instruments As of June 30, 2015 , the Company has multiple master netting agreements with a variety of entities that allow for cross-commodity netting under ASC 815-10-45. The Company does not have any agreements which allow for cross-affiliate netting among multiple affiliated legal entities. The amounts recorded on the Condensed Consolidated Balance Sheet as of June 30, 2015 and December 31, 2014 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 June 30, 2015 (in thousands): Fair Value Derivative Balance Sheet Location Gross Asset Gross Liability Collateral Netting Net Asset (Liability) in Balance Sheet Foreign currency contracts Other current liabilities $ 4 $ (74 ) $ — $ (70 ) Interest rate contracts Other current assets 1,781 (325 ) — 1,456 Interest rate contracts Other property and investments-net 250 — — 250 Interest rate contracts Other current liabilities — (5,715 ) — (5,715 ) Interest rate contracts Other non-current liabilities and deferred credits 7,589 (53,364 ) 22,400 (23,375 ) Commodity contracts Current utility energy commodity derivative assets 544 (60 ) — 484 Commodity contracts Current utility energy commodity derivative liabilities 51,995 (73,946 ) 9,270 (12,681 ) Commodity contracts Other non-current liabilities and deferred credits 20,190 (48,404 ) 7,092 (21,122 ) Total derivative instruments recorded on the balance sheet $ 82,353 $ (181,888 ) $ 38,762 $ (60,773 ) The following table presents the fair values and locations of derivative instruments recorded on the Condensed Consolidated Balance Sheet as of December 31, 2014 (in thousands): Fair Value Derivative Balance Sheet Location Gross Asset Gross Liability Collateral Netting Net Asset (Liability) in Balance Sheet Foreign currency contracts Other current liabilities $ 1 $ (21 ) $ — $ (20 ) Interest rate contracts Other current assets 966 (506 ) — 460 Interest rate contracts Other current liabilities — (7,325 ) — (7,325 ) Interest rate contracts Other non-current liabilities and deferred credits — (69,737 ) 28,880 (40,857 ) Commodity contracts Current utility energy commodity derivative assets 2,063 (538 ) — 1,525 Commodity contracts Current utility energy commodity derivative liabilities 66,421 (97,586 ) 13,120 (18,045 ) Commodity contracts Other non-current liabilities and deferred credits 29,594 (54,077 ) 2,390 (22,093 ) Total derivative instruments recorded on the balance sheet $ 99,045 $ (229,790 ) $ 44,390 $ (86,355 ) Exposure to Demands for Collateral The Company'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 the Company's credit ratings or changes in market prices. In periods of price volatility, the level of exposure can change significantly. As a result, sudden and significant demands may be made against the Company's credit facilities and cash. The Company actively monitors the exposure to possible collateral calls and takes steps to mitigate capital requirements. The following table presents the Company's collateral outstanding related to its derivative instruments as of June 30, 2015 and December 31, 2014 (in thousands): June 30, December 31, 2015 2014 Energy commodity derivatives Cash collateral posted $ 27,953 $ 20,565 Letters of credit outstanding 20,000 14,500 Balance sheet offsetting (cash collateral against net derivative positions) 16,362 15,510 Interest rate swaps Cash collateral posted 22,400 28,880 Letters of credit outstanding 7,200 10,900 Balance sheet offsetting (cash collateral against net derivative positions) 22,400 28,880 Certain of the Company’s derivative instruments contain provisions that require the Company to maintain an "investment grade" credit rating from the major credit rating agencies. If the Company’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 the Company could be required to post as of June 30, 2015 and December 31, 2014 (in thousands): June 30, December 31, 2015 2014 Liabilities with credit-risk-related contingent features $ 6,684 $ 12,911 Additional collateral to post 6,682 16,227 Credit Risk Credit risk relates to the potential losses that the Company would incur as a result of non-performance by counterparties of their contractual obligations to deliver energy or make financial settlements. The Company often extends credit to counterparties and customers and is exposed to the risk that it may not be able to collect amounts owed to the Company. Credit risk includes potential counterparty default due to circumstances: • relating directly to it, • caused by market price changes, and • relating to other market participants that have a direct or indirect relationship with such counterparty. Changes in market prices may dramatically alter the size of credit risk with counterparties, even when conservative credit limits are established. Should a counterparty fail to perform, the Company may be required to honor the underlying commitment or to replace existing contracts with contracts at then-current market prices. The Company enters into bilateral transactions with various counterparties. The Company also trades energy and related derivative instruments through clearinghouse exchanges. The Company seeks to mitigate bilateral credit risk by: • entering into bilateral contracts that specify credit terms and protections against default, • applying credit limits and duration criteria to existing and prospective counterparties, • actively monitoring current credit exposures, • asserting our collateral rights with counterparties, • carrying out transaction settlements timely and effectively, and • conducting transactions on exchanges with fully collateralized clearing arrangements that significantly reduce counterparty default risk. The Company's credit policy requires an evaluation of the financial condition of counterparties. Credit risk management includes collateral requirements or other credit enhancements, such as letters of credit or parent company guarantees. The Company enters into various agreements that address credit risks including standardized agreements that allow for the netting or offsetting of positive and negative exposures. The Company has concentrations of suppliers and customers in the electric and natural gas industries including: • electric and natural gas utilities, • electric generators and transmission providers, • natural gas producers and pipelines, • financial institutions including commodity clearing exchanges and related parties, and • energy marketing and trading companies. In addition, the Company has concentrations of credit risk related to geographic location as it operates in the western United States and western Canada. These concentrations of counterparties and concentrations of geographic location may impact the Company’s overall exposure to credit risk because the counterparties may be similarly affected by changes in conditions. The Company maintains credit support agreements with certain counterparties and margin calls are periodically made and/or received. Margin calls are triggered when exposures exceed contractual limits or when there are changes in a counterparty’s creditworthiness. Price movements in electricity and natural gas can generate exposure levels in excess of these contractual limits. Negotiating for collateral in the form of cash, letters of credit, or performance guarantees is common industry practice.

Asset Retirement Obligations As

Asset Retirement Obligations Asset Retirement Obligations (Notes)	6 Months Ended
	Jun. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation Disclosure [Text Block]	ASSET RETIREMENT OBLIGATIONS The Company records the fair value of a liability for an asset retirement obligation (ARO) in the period in which it is incurred. When the liability is initially recorded, the associated costs of the ARO are capitalized as part of the carrying amount of the related long-lived asset. The liability is accreted to its present value each period and the related capitalized costs are depreciated over the useful life of the related asset. Upon retirement of the asset, the Company either settles the ARO for its recorded amount or incurs a gain or loss. The Company records regulatory assets and liabilities for the difference between asset retirement costs currently recovered in rates and AROs recorded since asset retirement costs are recovered through rates charged to customers. Specifically, the Company has recorded liabilities for future asset retirement obligations to: • restore ponds at Colstrip, • cap a landfill at the Kettle Falls Plant, • remove plant and restore the land at the Coyote Springs 2 site at the termination of the land lease, and • dispose of PCBs in certain transformers. Due to an inability to estimate a range of settlement dates, the Company cannot estimate a liability for the: • removal and disposal of certain transmission and distribution assets, and • abandonment and decommissioning of certain hydroelectric generation and natural gas storage facilities. On April 17, 2015, the EPA published a final rule regarding coal combustion residuals (CCRs), also termed coal combustion byproducts or coal ash in the Federal Register and this rule becomes effective on October 15, 2015. Colstrip, of which Avista Corp. is a 15 percent owner of units 3 and 4, produces this byproduct. The rule establishes technical requirements for CCR landfills and surface impoundments under Subtitle D of the Resource Conservation and Recovery Act, the nation's primary law for regulating solid waste. The Company in conjunction with the other Owners’ is developing a multi-year compliance plan to strategically address the new CCR requirements and existing State obligations while maintaining operational stability. During the second quarter of 2015, the operator of Colstrip provided an initial cost estimate of the expected retirement costs associated with complying with the new CCR rule. Based on the initial assessment, Avista Corp. recorded an increase to its asset retirement obligations of $11.7 million with a corresponding increase in the cost basis of the utility plant. The actual asset retirement costs related to the CCR Rule requirements may vary substantially from the estimates used to record the increased obligation due to uncertainty about the compliance strategies that will be used and the preliminary nature of available data used to estimate costs, such as the quantity of coal ash present at certain sites and the volume of fill that will be needed to cap and cover certain impoundments. Avista Corp. will coordinate with the plant operator and continue to gather additional data in future periods to make decisions about compliance strategies and the timing of closure activities. As additional information becomes available, Avista Corp. will update the ARO for these changes in estimates, which could be material. The Company expects to seek recovery of any increased costs related to complying with the new rule through customer rates. The following table documents the changes in the Company’s asset retirement obligation for the period December 31, 2014 through June 30, 2015 (dollars in thousands): 2015 Asset retirement obligation at December 31, 2014 $ 3,028 Liabilities incurred 11,658 Liabilities settled (6 ) Accretion expense 111 Asset retirement obligation at June 30, 2015 $ 14,791

Pension Plans And Other Postret

Pension Plans And Other Postretirement Benefit Plans	6 Months Ended
	Jun. 30, 2015
General Discussion of Pension and Other Postretirement Benefits [Abstract]
Pension Plans and Other Postretirement Benefit Plans	PENSION PLANS AND OTHER POSTRETIREMENT BENEFIT PLANS The pension and other postretirement benefit plans described below only relate to Avista Utilities and AEL&P. METALfx (not discussed below) has a salary deferral 401(k) savings plan that is a defined contribution plan and is not significant to the Company. Avista Utilities The Company has a defined benefit pension plan covering the majority of all regular full-time employees at Avista Utilities that were hired prior to January 1, 2014. Individual benefits under this plan are based upon the employee’s years of service, date of hire and average compensation as specified in the plan. Non-union employees hired on or after January 1, 2014 participate in a defined contribution 401(k) plan in lieu of a defined benefit pension plan. 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 $8.0 million in cash to the pension plan for the six months ended June 30, 2015 and expects to contribute a total of $12.0 million in cash to the plan during 2015. The Company contributed $32.0 million in cash to the pension plan in 2014 . The Company also has a Supplemental Executive Retirement Plan (SERP) that provides additional pension benefits to executive officers and certain key employees of the Company. The SERP is intended to provide benefits to individuals whose benefits under the pension plan are reduced due to the application of Section 415 of the Internal Revenue Code of 1986 and the deferral of salary under deferred compensation plans. The liability and expense for this plan are included as pension benefits in the tables included in this Note. The Company provides certain health care and life insurance benefits for eligible retired employees that were hired prior to January 1, 2014. The Company accrues the estimated cost of postretirement benefit obligations during the years that employees provide services. The liability and expense of this plan are included as other postretirement benefits. Non-union employees hired on or after January 1, 2014 will have access to the retiree medical plan upon retirement; however, Avista Corp. will no longer provide a contribution toward their medical premium. The Company has a Health Reimbursement Arrangement to provide employees with tax-advantaged funds to pay for allowable medical expenses upon retirement. The amount earned by the employee is fixed on the retirement date based on the employee’s years of service and the ending salary. The liability and expense of this plan are included as other postretirement benefits. The Company provides death benefits to beneficiaries of executive officers who die during their term of office or after retirement. Under the plan, an executive officer’s designated beneficiary will receive a payment equal to twice the executive officer’s annual base salary at the time of death (or if death occurs after retirement, a payment equal to twice the executive officer’s total annual pension benefit). The liability and expense for this plan are included as other postretirement benefits. The Company uses a December 31 measurement date for its pension and other postretirement benefit plans. The following table sets forth the components of net periodic benefit costs for the three and six months ended June 30 (dollars in thousands): Pension Benefits Other Post-retirement Benefits 2015 2014 2015 2014 Three months ended June 30: Service cost $ 4,984 $ 3,868 $ 721 $ 499 Interest cost 6,531 6,706 1,292 1,353 Expected return on plan assets (7,075 ) (8,110 ) (500 ) (472 ) Amortization of prior service cost 6 6 (287 ) (43 ) Net loss recognition 2,634 14 1,263 349 Net periodic benefit cost $ 7,080 $ 2,484 $ 2,489 $ 1,686 Six months ended June 30: Service cost $ 9,933 $ 8,886 $ 1,420 $ 1,473 Interest cost 13,203 13,412 2,623 2,706 Expected return on plan assets (14,491 ) (16,220 ) (931 ) (944 ) Amortization of prior service cost 12 12 (566 ) (86 ) Net loss recognition 5,028 1,171 2,555 1,175 Net periodic benefit cost $ 13,685 $ 7,261 $ 5,101 $ 4,324 AEL&P Union Employees Pension benefits for all union employees of AEL&P are provided through the Alaska Electrical Pension Fund Retirement Plan, a multiemployer plan to which AEL&P pays a defined contribution amount per union employee pursuant to a collective bargaining agreement with the IBEW. AEL&P also participates in a multiemployer plan that provides substantially all union workers with health care and other welfare benefits during their working lives and after retirement. AEL&P pays a defined contribution amount per union employee pursuant to a collective bargaining agreement with the IBEW. Non-Union Employees AEL&P has a defined contribution money purchase pension plan covering substantially all employees of AEL&P that are not covered by a collective bargaining agreement. Contributions to the plan are made based on a percentage of each qualifying employee's compensation. AEL&P also has a noncontributory 401(k) savings plan, which covers substantially all nonunion employees who have completed 1,000 hours of service during a 12-month period. Employees who elect to participate may contribute up to the Internal Revenue Service's maximum amount. The pension and other postretirement plans described above for AEL&P are not material to Avista Corp.

Committed Lines of Credit

Committed Lines of Credit	6 Months Ended
	Jun. 30, 2015
Short-term Debt [Abstract]
Committed Lines of Credit	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 that expires in April 2019 . Balances outstanding and interest rates of borrowings (excluding letters of credit) under the Company’s revolving committed lines of credit were as follows as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Borrowings outstanding at end of period $ 90,000 $ 105,000 Letters of credit outstanding at end of period $ 34,379 $ 32,579 Average interest rate on borrowings at end of period 0.94 % 0.93 % AEL&P AEL&P has a committed line of credit in the amount of $25.0 million that expires in November 2019 . As of June 30, 2015 and December 31, 2014 , there were no borrowings outstanding under this committed line of credit.

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2015
Long-term Debt, Unclassified [Abstract]
Long-Term Debt	LONG-TERM DEBT The following details long-term debt outstanding as of June 30, 2015 and December 31, 2014 (dollars in thousands): Maturity Interest June 30, December 31, Year Description Rate 2015 2014 Avista Corp. Secured Long-Term Debt 2016 First Mortgage Bonds 0.84% $ 90,000 $ 90,000 2018 First Mortgage Bonds 5.95% 250,000 250,000 2018 Secured Medium-Term Notes 7.39%-7.45% 22,500 22,500 2019 First Mortgage Bonds 5.45% 90,000 90,000 2020 First Mortgage Bonds 3.89% 52,000 52,000 2022 First Mortgage Bonds 5.13% 250,000 250,000 2023 Secured Medium-Term Notes 7.18%-7.54% 13,500 13,500 2028 Secured Medium-Term Notes 6.37% 25,000 25,000 2032 Secured Pollution Control Bonds (1) (1) 66,700 66,700 2034 Secured Pollution Control Bonds (1) (1) 17,000 17,000 2035 First Mortgage Bonds 6.25% 150,000 150,000 2037 First Mortgage Bonds 5.70% 150,000 150,000 2040 First Mortgage Bonds 5.55% 35,000 35,000 2041 First Mortgage Bonds 4.45% 85,000 85,000 2044 First Mortgage Bonds 4.11% 60,000 60,000 2047 First Mortgage Bonds 4.23% 80,000 80,000 Total Avista Corp. secured long-term debt 1,436,700 1,436,700 Alaska Electric Light and Power Company Secured Long-Term Debt 2044 First Mortgage Bonds 4.54% 75,000 75,000 Total consolidated secured long-term debt 1,511,700 1,511,700 Alaska Energy and Resources Company Unsecured Long-Term Debt 2019 Unsecured Term Loan 3.85% 15,000 15,000 Total secured and unsecured long-term debt 1,526,700 1,526,700 Capital lease obligations 73,422 74,149 Settled interest rate swaps (2) (17,336 ) (17,541 ) Unamortized debt discount (1,039 ) (1,122 ) Total 1,581,747 1,582,186 Secured Pollution Control Bonds held by Avista Corporation (1) (83,700 ) (83,700 ) Current portion of long-term debt and capital leases (3,162 ) (6,424 ) Total long-term debt and capital leases $ 1,494,885 $ 1,492,062 (1) In December 2010, $66.7 million and $17.0 million of the City of Forsyth, Montana Pollution Control Revenue Refunding Bonds (Avista Corporation Colstrip Project) due in 2032 and 2034 , respectively, which had been held by Avista Corp. since 2008 and 2009, respectively, were refunded by new bond issues (Series 2010A and Series 2010B). The new bonds were not offered to the public and were purchased by Avista Corp. due to market conditions. The Company expects that at a later date, subject to market conditions, these bonds may be remarketed to unaffiliated investors. So long as Avista Corp. is the holder of these bonds, the bonds will not be reflected as an asset or a liability on Avista Corp.'s Condensed Consolidated Balance Sheets. (2) Upon settlement of interest rate swaps, these are recorded as a regulatory asset or liability and included as part of long-term debt above. They are amortized as a component of interest expense over the life of the associated debt and included as a part of the Company's cost of debt calculation for ratemaking purposes. Snettisham Capital Lease Obligation Included in long-term capital leases above is a power purchase agreement between AEL&P and Alaska Industrial Development and Export Authority (AIDEA), an agency of the State of Alaska, under which AEL&P has a take-or-pay obligation, expiring in December 2038, to purchase all the output of the 78 MW Snettisham hydroelectric project. For accounting purposes, this power purchase agreement is treated as a capital lease. The balances related to the Snettisham capital lease obligation as of June 30, 2015 and December 31, 2014 were as follows (dollars in thousands): June 30, December 31, 2015 2014 Capital lease obligation (1) $ 68,840 $ 69,955 Capital lease asset (2) 71,007 71,007 Accumulated amortization of capital lease asset (2) 3,641 1,821 (1) The capital lease obligation amount is equal to the amount of AIDEA's revenue bonds outstanding. (2) These amounts are included in utility plant in service on the Condensed Consolidated Balance Sheet. Interest on the capital lease obligation and amortization of the capital lease asset are included in utility resource costs in the Condensed Consolidated Statements of Income and totaled the following amounts for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Interest on capital lease obligation $ 922 $ — $ 1,845 $ — Amortization of capital lease asset 910 — 1,820 — AIDEA issued $100.0 million in revenue bonds in 1998 to finance its acquisition of the project and the payments by AEL&P are designed to be more than sufficient to enable the AIDEA to pay the principal and interest amount of its revenue bonds, bearing interest at rates ranging from 4.9 percent to 6.0 percent and maturing in January 2034. AEL&P will make its last bond payment to AIDEA in December 2033. The payments by AEL&P under the agreement are unconditional, notwithstanding any suspension, reduction or curtailment of the operation of the project. The bonds are payable solely out of AIDEA's receipts under the agreement. AEL&P is also obligated to operate, maintain and insure the project. AEL&P's payments for power under the agreement are approximately $10.6 million per year, while debt service on the bonds is approximately $5.9 million per year, which is included in the $10.6 million total cost of power. In May 2015, AIDEA posted a notice on the Electronic Municipal Market Access and the Bloomberg websites indicating it is considering an offering of tax-exempt refunding bonds with the purpose of refunding all or a portion of their outstanding revenue bonds associated with the Snettisham Hydroelectric Project. The transaction is currently anticipated to price in August 2015. The size and timing of the anticipated transaction remains subject to market conditions and AIDEA reserves the right to change or modify its plans as it deems appropriate. AIDEA is under no obligation to pursue this transaction or any other new money or refunding issue and there is no guarantee any contemplated transactions will be consummated. Snettisham Electric Company, a non-operating subsidiary of AERC, has the option to purchase the Snettisham project with certain conditions at any time for the principal amount of the bonds outstanding at that time. While the power purchase agreement is treated as a capital lease for accounting purposes, for ratemaking purposes, this agreement is treated as an operating lease with a constant level of annual rental expense (straight line expense). Because of this regulatory treatment, any difference between the operating lease expense for ratemaking purposes and the expenses recognized under capital lease treatment (interest and depreciation of the capital lease asset) is recorded as a regulatory asset and amortized during the later years of the lease when the capital lease expense is less than the operating lease expense included in base rates. The Company evaluated this agreement to determine if it has a variable interest which must be consolidated. Based on this evaluation, AIDEA will not be consolidated under ASC 810 "Consolidation" because AIDEA is a government agency and ASC 810 has a specific scope exception which does not allow for the consolidation of government organizations. The following table details future capital lease obligations, including interest, under the Snettisham PPA (dollars in thousands): Remaining 2015 2016 2017 2018 2019 Thereafter Total Principal $ 1,115 $ 2,350 $ 2,480 $ 2,615 $ 2,755 $ 57,525 $ 68,840 Interest 1,845 3,567 3,438 3,305 3,165 25,364 40,684 Total $ 2,960 $ 5,917 $ 5,918 $ 5,920 $ 5,920 $ 82,889 $ 109,524

Long- Term Debt to Affiliated T

Long- Term Debt to Affiliated Trust Long-Term Debt to Affiliated Trust (Notes)	6 Months Ended
	Jun. 30, 2015
Long-Term Debt to Affiliated Trust [Abstract]
Long Term Debt To Affiliated Trusts Disclosure [Text Block]	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 six months ended June 30, 2015 and the year ended December 31, 2014 : June 30, December 31, 2015 2014 Low distribution rate 1.11 % 1.10 % High distribution rate 1.16 % 1.11 % Distribution rate at the end of the period 1.16 % 1.11 % Concurrent with the issuance of the Preferred Trust Securities, Avista Capital II issued $1.5 million of Common Trust Securities to the Company. These debt securities may be redeemed at the option of Avista Capital II on or after June 1, 2007 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 Value	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value	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), nonrecourse long-term debt 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 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, 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 June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, 2015 December 31, 2014 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Long-term debt (Level 2) $ 951,000 $ 1,087,197 $ 951,000 $ 1,118,972 Long-term debt (Level 3) 492,000 496,848 492,000 527,663 Snettisham capital lease obligation (Level 3) 68,840 75,174 69,955 79,290 Nonrecourse long-term debt (Level 3) — — 1,431 1,440 Long-term debt to affiliated trusts (Level 3) 51,547 37,629 51,547 38,582 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 73.00 to 123.32 , where a par value of 100.0 represents the carrying value recorded on the Consolidated Balance Sheets. Due to the unique nature of the Snettisham capital lease obligation, the estimated fair value of this item was determined based on a discounted cash flow model using available market information. The Snettisham capital lease obligation was discounted to present value using the Moody's Aaa Corporate discount rate as published by the Federal Reserve on June 30, 2015 . 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 June 30, 2015 and December 31, 2014 at fair value on a recurring basis (dollars in thousands): Level 1 Level 2 Level 3 Counterparty Total June 30, 2015 Assets: Energy commodity derivatives $ — $ 72,728 $ — $ (72,244 ) $ 484 Level 3 energy commodity derivatives: Natural gas exchange agreement — — 1 (1 ) — Foreign currency derivatives — 4 — (4 ) — Interest rate swaps — 9,620 — (7,914 ) 1,706 Deferred compensation assets: Fixed income securities (2) 1,830 — — — 1,830 Equity securities (2) 6,199 — — — 6,199 Total $ 8,029 $ 82,352 $ 1 $ (80,163 ) $ 10,219 Liabilities: Energy commodity derivatives $ — $ 96,823 $ — $ (88,606 ) $ 8,217 Level 3 energy commodity derivatives: Natural gas exchange agreement — — 6,826 (1 ) 6,825 Power exchange agreement — — 18,616 — 18,616 Power option agreement — — 145 — 145 Foreign currency derivatives — 74 — (4 ) 70 Interest rate swaps — 59,404 — (30,314 ) 29,090 Total $ — $ 156,301 $ 25,587 $ (118,925 ) $ 62,963 Level 1 Level 2 Level 3 Counterparty Total December 31, 2014 Assets: Energy commodity derivatives $ — $ 96,729 $ — $ (95,204 ) $ 1,525 Level 3 energy commodity derivatives: Natural gas exchange agreement — — 1,349 (1,349 ) — Foreign currency derivatives — 1 — (1 ) — Interest rate swaps — 966 — (506 ) 460 Funds held in trust account of Spokane Energy 1,600 — — — 1,600 Deferred compensation assets: Fixed income securities (2) 1,793 — — — 1,793 Equity securities (2) 6,074 — — — 6,074 Total $ 9,467 $ 97,696 $ 1,349 $ (97,060 ) $ 11,452 Liabilities: Energy commodity derivatives $ — $ 127,094 $ — $ (110,714 ) $ 16,380 Level 3 energy commodity derivatives: Natural gas exchange agreement — — 1,384 (1,349 ) 35 Power exchange agreement — — 23,299 — 23,299 Power option agreement — — 424 — 424 Interest rate swaps — 77,568 — (29,386 ) 48,182 Foreign currency derivatives — 21 — (1 ) 20 Total $ — $ 204,683 $ 25,107 $ (141,450 ) $ 88,340 (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 trading securities and are included in other property and investments-net on the Condensed Consolidated Balance Sheets. Avista Corp. enters into forward contracts to purchase or sell a specified amount of energy at a specified time, or during a specified period, in the future. These contracts are entered into as part of Avista Corp.’s management of loads and resources and certain contracts are considered derivative instruments. The difference between the amount of derivative assets and liabilities disclosed in respective levels and the amount of derivative assets and liabilities disclosed on the Condensed Consolidated Balance Sheets is due to netting arrangements with certain counterparties. The Company uses quoted market prices and forward price curves to estimate the fair value of utility derivative commodity instruments included in Level 2. In particular, electric derivative valuations are performed using broker quotes, adjusted for periods in between quotable periods. Natural gas derivative valuations are estimated using New York Mercantile Exchange (NYMEX) pricing for similar instruments, adjusted for basin differences, using broker quotes. Where observable inputs are available for substantially the full term of the contract, the derivative asset or liability is included in Level 2. 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 $0.7 million as of June 30, 2015 and $0.8 million as of December 31, 2014 . Level 3 Fair Value For the power exchange agreement, the Company compares the Level 2 brokered quotes and forward price curves described above to an internally developed forward price which is based on the average operating and maintenance (O&M) charges from four surrogate nuclear power plants around the country for the current year. Because the nuclear power plant O&M charges are only known for one year, all forward years are estimated assuming an annual escalation. In addition to the forward price being estimated using unobservable inputs, the Company also estimates the volumes of the transactions that will take place in the future based on historical average transaction volumes per delivery year (November to April). Significant increases or decreases in any of these inputs in isolation would result in a significantly higher or lower fair value measurement. Generally, a change in the current year O&M charges for the surrogate plants is accompanied by a directionally similar change in O&M charges in future years. There is generally not a correlation between external market prices and the O&M charges used to develop the internal forward price. For the power commodity option agreement, the Company uses the Black-Scholes-Merton valuation model to estimate the fair value, and this model includes significant inputs not observable or corroborated in the market. These inputs include; 1) the strike price (which is an internally derived price based on a combination of generation plant heat rate factors, natural gas market pricing, delivery and other O&M charges), 2) estimated delivery volumes, and 3) volatility rates for periods beyond July 2018 . Significant increases or decreases in any of these inputs in isolation would result in a significantly higher or lower fair value measurement. Generally, changes in overall commodity market prices and volatility rates are accompanied by directionally similar changes in the strike price and volatility assumptions used in the calculation. For the natural gas commodity exchange agreement, the Company uses the same Level 2 brokered quotes described above; however, the Company also estimates the purchase and sales volumes (within contractual limits) as well as the timing of those transactions. Changing the timing of volume estimates changes the timing of purchases and sales, impacting which brokered quote is used. Because the brokered quotes can vary significantly from period to period, the unobservable estimates of the timing and volume of transactions can have a significant impact on the calculated fair value. The Company currently estimates volumes and timing of transactions based on a most likely scenario using historical data. Historically, the timing and volume of transactions have not been highly correlated with market prices and market volatility. The following table presents the quantitative information which was used to estimate the fair values of the Level 3 assets and liabilities above as of June 30, 2015 (dollars in thousands): Fair Value (Net) at June 30, 2015 Valuation Technique Unobservable Input Range Power exchange agreement $ (18,616 ) Surrogate facility pricing O&M charges $30.66-$55.56/MWh (1) Escalation factor 3% - 2015 to 2019 Transaction volumes 392,608 - 397,030 MWhs Power option agreement (145 ) Black-Scholes- Merton Strike price $43.44/MWh - 2015 $55.66/MWh - 2019 Delivery volumes 128,278 - 287,147 MWhs Volatility rates 0.20 (2) Natural gas exchange agreement (6,825 ) Internally derived Forward purchase prices $2.27 - $3.19/mmBTU Forward sales prices $2.47 - $4.08/mmBTU Purchase volumes 125,000 - 310,000 mmBTUs Sales volumes 60,000 - 310,000 mmBTUs (1) The average O&M charges for the delivery year beginning in November 2014 were $42.90 per MWh. For ratemaking purposes the average O&M charges to be included for recovery in retail rates vary slightly between regulatory jurisdictions. The average O&M charges for the delivery year beginning in 2014 were $43.11 for Washington and $42.90 for Idaho. (2) The estimated volatility rate of 0.20 is compared to actual quoted volatility rates of 0.39 for 2015 to 0.20 in July 2018 . Avista Corp.'s Risk Management team and accounting team are responsible for developing the valuation methods described above and both groups report to the Chief Financial Officer. The valuation methods, significant inputs and resulting fair values described above are reviewed on at least a quarterly basis by the risk management team and the accounting team to ensure they provide a reasonable estimate of fair value each reporting period. The following table presents activity for energy commodity derivative assets (liabilities) measured at fair value using significant unobservable inputs (Level 3) for the three and six months ended June 30 (dollars in thousands): Natural Gas Exchange Agreement Power Exchange Agreement Power Option Agreement Total Three months ended June 30, 2015: Balance as of April 1, 2015 $ 817 $ (25,903 ) $ (251 ) $ (25,337 ) Total gains or losses (realized/unrealized): Included in net income — — — — Included in other comprehensive income — — — — Included in regulatory assets/liabilities (8,163 ) 6,551 106 (1,506 ) Purchases — — — — Issuance — — — — Settlements 521 736 — 1,257 Transfers to/from other categories — — — — Ending balance as of June 30, 2015 $ (6,825 ) $ (18,616 ) $ (145 ) $ (25,586 ) Three months ended June 30, 2014: Balance as of April 1, 2014 $ (2,418 ) $ (13,624 ) $ (428 ) $ (16,470 ) Total gains or losses (realized/unrealized): Included in net income — — — — Included in other comprehensive income — — — — Included in regulatory assets/liabilities 235 5,029 (177 ) 5,087 Purchases — — — — Issuance — — — — Settlements — 676 — 676 Transfers to/from other categories — — — — Ending balance as of June 30, 2014 $ (2,183 ) $ (7,919 ) $ (605 ) $ (10,707 ) Six months ended June 30, 2015: Balance as of January 1, 2015 $ (35 ) $ (23,299 ) $ (424 ) $ (23,758 ) Total gains or losses (realized/unrealized): Included in net income — — — — Included in other comprehensive income — — — — Included in regulatory assets/liabilities (7,386 ) 170 279 (6,937 ) Purchases — — — — Issuance — — — — Settlements 596 4,513 — 5,109 Transfers to/from other categories — — — — Ending balance as of June 30, 2015 $ (6,825 ) $ (18,616 ) $ (145 ) $ (25,586 ) Natural Gas Exchange Agreement Power Exchange Agreement Power Option Agreement Total Six months ended June 30, 2014: Balance as of January 1, 2014 $ (1,219 ) $ (14,441 ) $ (775 ) $ (16,435 ) Total gains or losses (realized/unrealized): Included in net income — — — — Included in other comprehensive income — — — — Included in regulatory assets/liabilities 2,084 7,055 170 9,309 Purchases — — — — Issuance — — — — Settlements (3,048 ) (533 ) — (3,581 ) Transfers from other categories — — — — Ending balance as of June 30, 2014 $ (2,183 ) $ (7,919 ) $ (605 ) $ (10,707 )

Earnings Per Common Share Attri

Earnings Per Common Share Attributable To Avista Corporation	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Common Share Attributable To Avista Corporation Shareholders	EARNINGS PER COMMON SHARE ATTRIBUTABLE TO AVISTA CORP. SHAREHOLDERS The following table presents the computation of basic and diluted earnings per common share attributable to Avista Corp. shareholders for the three and six months ended June 30 (in thousands, except per share amounts): Three months ended Six months ended June 30, June 30, 2015 2014 2015 2014 Numerator: Net income from continuing operations attributable to Avista Corp. shareholders $ 25,050 $ 31,254 $ 71,499 $ 78,730 Net income from discontinued operations attributable to Avista Corp. shareholders 196 69,617 196 70,640 Subsidiary earnings adjustment for dilutive securities (discontinued operations) — 58 — 5 Adjusted net income from discontinued operations attributable to Avista Corp. shareholders for computation of diluted earnings per common share $ 196 $ 69,675 $ 196 $ 70,645 Denominator: Weighted-average number of common shares outstanding-basic 62,281 60,184 62,299 60,153 Effect of dilutive securities: Performance and restricted stock awards 319 279 445 163 Weighted-average number of common shares outstanding-diluted 62,600 60,463 62,744 60,316 Earnings per common share attributable to Avista Corp. shareholders, basic: Earnings per common share from continuing operations $ 0.41 $ 0.52 $ 1.15 $ 1.31 Earnings per common share from discontinued operations $ — $ 1.16 $ — $ 1.17 Total earnings per common share attributable to Avista Corp. shareholders, basic $ 0.41 $ 1.68 $ 1.15 $ 2.48 Earnings per common share attributable to Avista Corp. shareholders, diluted: Earnings per common share from continuing operations $ 0.40 $ 0.52 $ 1.14 $ 1.31 Earnings per common share from discontinued operations $ — $ 1.15 $ — $ 1.17 Total earnings per common share attributable to Avista Corp. shareholders, diluted $ 0.40 $ 1.67 $ 1.14 $ 2.48 There were no shares excluded from the calculation because they were antidilutive.

Commitments And Contingencies

Commitments And Contingencies	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	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. Pacific Northwest Refund Proceeding In July 2001, the Federal Energy Regulatory Commission (“FERC” or “Commission”) initiated a preliminary evidentiary hearing to develop a factual record as to whether prices for spot market sales of wholesale energy in the Pacific Northwest between December 25, 2000 and June 20, 2001 were just and reasonable. In June 2003, the FERC terminated the Pacific Northwest refund proceedings, after finding that the equities do not justify the imposition of refunds. In August 2007, the Ninth Circuit found that the FERC had failed to take into account new evidence of market manipulation and that such failure was arbitrary and capricious and, accordingly, remanded the case to the FERC, stating that the FERC's findings must be reevaluated in light of the new evidence. The Ninth Circuit expressly declined to direct the FERC to grant refunds. On October 3, 2011, the FERC issued an Order on Remand. On April 5, 2013, the FERC issued an Order on Rehearing expanding the temporal scope of the proceeding to permit parties to submit evidence on transactions during the period from January 1, 2000 through and including June 20, 2001. The Order on Remand established an evidentiary, trial-type hearing before an ALJ, and reopened the record to permit parties to present evidence of unlawful market activity. The Order on Remand stated that parties seeking refunds must submit evidence demonstrating that specific unlawful market activity occurred, and must demonstrate that such activity directly affected negotiations with respect to the specific contract rate about which they complain. Simply alleging a general link between the dysfunctional spot market in California and the Pacific Northwest spot market would not be sufficient to establish a causal connection between a particular seller's alleged unlawful activities and the specific contract negotiations at issue. The hearing was conducted in August through October 2013. On July 11, 2012 and March 28, 2013, Avista Energy and Avista Utilities filed settlements of all issues in this docket with regard to the claims made by the City of Tacoma and the California AG (on behalf of CERS). The FERC has approved the settlements and they are final. The remaining direct claimant against Avista Utilities and Avista Energy in this proceeding is the City of Seattle, Washington (Seattle). With regard to the Seattle claims, on March 28, 2014, the Presiding ALJ issued her Initial Decision finding that: 1) Seattle failed to demonstrate that either Avista Utilities or Avista Energy engaged in unlawful market activity and also failed to identify any specific contracts at issue; 2) Seattle failed to demonstrate that contracts with either Avista Utilities or Avista Energy imposed an excessive burden on consumers or seriously harmed the public interest; and that 3) Seattle failed to demonstrate that either Avista Utilities or Avista Energy engaged in any specific violations of substantive provisions of the Federal Power Act or any filed tariffs or rate schedules. Accordingly, the ALJ denied all of Seattle’s claims under both section 206 and section 309 of the Federal Power Act. On May 22, 2015, the FERC issued its Order on Initial Decision in which it upheld the ALJ’s Initial Decision denying all of Seattle’s claims against Avista Utilities and Avista Energy. Seattle has filed a Request for Rehearing of the FERC’s Order on Initial Decision. The Company does not expect that this matter will have a material adverse effect on its financial condition, results of operations or cash flows. Sierra Club and Montana Environmental Information Center Litigation On March 6, 2013, the Sierra Club and Montana Environmental Information Center (MEIC) (collectively "Plaintiffs"), filed a Complaint in the United States District Court for the District of Montana, Billings Division, against the Owners of the Colstrip Generating Project ("Colstrip"). Avista Corp. owns a 15 percent interest in Units 3 & 4 of Colstrip. The other Colstrip co-Owners are PPL Montana, Puget Sound Energy, Portland General Electric Company, NorthWestern Energy and PacifiCorp. The Complaint alleges certain violations of the Clean Air Act, including the New Source Review, Title V and opacity requirements. On September 27, 2013, the Plaintiffs filed an Amended Complaint. The Amended Complaint withdrew from the original Complaint fifteen claims related to seven pre-January 1, 2001 Colstrip maintenance projects, upgrade projects and work projects and claims alleging violations of Title V and opacity requirements. The Amended Complaint alleges certain violations of the Clean Air Act and the New Source Review and adds claims with respect to post-January 1, 2001 Colstrip projects. On August 27, 2014, the Plaintiffs filed a Second Amended Complaint. The Second Amended Complaint withdraws from the Amended Complaint five claims and adds one new claim. The Second Amended Complaint alleges certain violations of the Clean Air Act and the New Source Review. The Plaintiffs request that the Court grant injunctive and declaratory relief, order remediation of alleged environmental damages, impose civil penalties, require a beneficial environmental project in the areas affected by the alleged air pollution and require payment of Plaintiffs’ costs of litigation and attorney fees. The Plaintiffs have since indicated that they do not intend to pursue two of the seven projects, leaving a total of five projects remaining. The case has been bifurcated into separate liability and remedy trials. The Court has set the liability trial date for November 2015. No date has been set for the remedy trial. Management believes that it is reasonably possible that this matter could result in a loss to the Company. However, due to uncertainties concerning this matter, Avista Corp. cannot predict the outcome or determine whether it would have a material impact on the Company. Cabinet Gorge Total Dissolved Gas Abatement Plan Dissolved atmospheric gas levels (referred to as "TDG") in the Clark Fork River exceed state of Idaho and federal water quality numeric standards downstream of the Cabinet Gorge Hydroelectric Generating Project (Cabinet Gorge) during periods when excess river flows must be diverted over the spillway. Under the terms of the Clark Fork Settlement Agreement as incorporated in Avista Corp.'s FERC license for the Clark Fork Project, Avista Corp. has worked in consultation with agencies, tribes and other stakeholders to address this issue. Under the terms of a gas supersaturation mitigation plan, Avista is reducing TDG by constructing spill crest modifications on spill gates at the dam, and the Company expects to continue spill crest modifications over the next several years, in ongoing consultation with key stakeholders. The Company will continue to seek recovery, through the ratemaking process, of all operating and capitalized costs related to this issue. Fish Passage at Cabinet Gorge and Noxon Rapids In 1999, the United States Fish and Wildlife Service (USFWS) listed bull trout as threatened under the Endangered Species Act. In 2010, the USFWS issued a revised designation of critical habitat for bull trout, which includes the lower Clark Fork River. In 2014, the USFWS issued a revised draft bull trout recovery plan, with the stated expectation to finalize the plan in 2015. The Clark Fork Settlement Agreement describes programs intended to help restore bull trout populations in the project area. Using the concept of adaptive management and working closely with the USFWS, the Company evaluated the feasibility of fish passage at Cabinet Gorge and Noxon Rapids. The results of these studies led, in part, to the decision to move forward with development of permanent facilities, among other bull trout enhancement efforts. Fishway designs for Cabinet Gorge are still being finalized. Construction cost estimates and schedules will be developed after several remaining issues are resolved, related to Montana's approval of fish transport from Idaho and expected minimum discharge requirements. Fishway design for Noxon Rapids has also been initiated, and is still in early stages. The Company believes its ongoing efforts through the Clark Fork Settlement Agreement continue to effectively address issues related to bull trout. The Company will continue to seek recovery, through the ratemaking process, of all operating and capitalized costs related to fish passage at Cabinet Gorge and Noxon Rapids. Kettle Falls Generation Station - Diesel Spill Investigation and Remediation In December 2013, the Company's operations staff at the Kettle Falls Generation Station discovered that approximately 10,000 gallons of diesel fuel had leaked underground from the piping system used to fuel heavy equipment. Avista Corp. made all proper agency notifications and worked closely with the Washington State Department of Ecology (Ecology) during the spill response and investigation phase. The Company installed ground water monitoring wells and there is no indication that ground or surface water is threatened by the spill. There is no indication that Ecology is considering any enforcement action and the Company initiated a voluntary cleanup action with the installation of a recovery system. As of June 30, 2015 , the Company has recorded an estimated remediation liability and the Company will continue to monitor the remediation activities and will adjust any estimated remediation liability if necessary as new information is obtained. The Company does not expect that this matter will have a material effect on its financial condition, results of operations or cash flows. Collective Bargaining Agreements The Company’s collective bargaining agreements with the International Brotherhood of Electrical Workers (IBEW) represent approximately 45 percent of all of Avista Utilities’ employees. The agreement with the local union in Washington and Idaho representing the majority (approximately 90 percent ) of the Avista Utilities' bargaining unit employees expired in March 2014. A new two-year agreement with this group was approved in January 2015 and has an expiration of March 2016. A new three-year agreement in Oregon, which covers approximately 50 employees, was approved in April 2014. A new collective bargaining agreement with the local union of the IBEW in Alaska was signed in May 2013 and expires in March 2017. The collective bargaining agreement with the IBEW in Alaska represents approximately 54 percent of all AERC employees. Investment Commitments In October 2014, an indirect subsidiary of Avista Corp. entered into an agreement to fund a limited liability company in exchange for equity ownership in the limited liability company. This represents an unconditional commitment for $3.1 million , and the payments began in October 2014. As of June 30, 2015 , the remaining commitment under the agreement was $2.3 million . Customer Information and Work Management Systems Project Cost Recovery Over the past four years, Avista Corp. has invested significant capital into the replacement of its customer information and work management systems (Project Compass). Project Compass was completed and went into service during the first quarter of 2015. As part of the Washington electric and natural gas general rate cases filed in February 2015, Avista Utilities has requested the full recovery of the Washington share of the costs associated with this project. On July 27, 2015, the UTC Staff in the Company's electric and natural gas general rate cases filed responsive testimony. Included in their testimony was a recommendation to disallow $12.7 million (Washington's share) of Project Compass costs primarily related to the seven month delay in the full completion of the project. Avista Utilities has concluded that the likelihood that part of the cost of Project Compass will be disallowed for ratemaking purposes is less than probable. 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.

Information By Business Segment

Information By Business Segments	6 Months Ended
	Jun. 30, 2015
Segment Reporting [Abstract]
Information by Business Segments	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) attributable to Avista Corp. shareholders. 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. Ecova was a provider of facility information and cost management services for multi-site customers throughout North America. The Ecova business segment was disposed of as of June 30, 2014. All income statement amounts were reclassified to discontinued operations on the Condensed Consolidated Statements of Income for all periods presented. The Other category, which is not a reportable segment, includes Spokane Energy, other investments and operations of various subsidiaries, as well as certain other operations of Avista Capital. On July 1, 2014, the Company completed its acquisition of AERC. Based on the way AERC is managed and the financial reports that are reviewed by the Chief Operating Decision Maker, AEL&P, the primary subsidiary of AERC, is considered a separate reportable business segment and the remaining activities of AERC are included in the Other category. All goodwill associated with the AERC acquisition was assigned to the AEL&P reportable business segment. 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 June 30, 2015: Operating revenues $ 320,698 $ 10,232 $ 330,930 $ 6,502 $ (100 ) $ 337,332 Resource costs 137,896 3,220 141,116 — — 141,116 Other operating expenses 70,348 2,764 73,112 6,746 (100 ) 79,758 Depreciation and amortization 34,351 1,325 35,676 165 — 35,841 Income (loss) from operations 55,415 2,354 57,769 (409 ) — 57,360 Interest expense (2) 18,969 895 19,864 147 (30 ) 19,981 Income taxes 14,632 591 15,223 (207 ) — 15,016 Net income (loss) from continuing operations attributable to Avista Corp. shareholders 24,478 925 25,403 (353 ) — 25,050 Capital expenditures (3) 90,800 5,355 96,155 92 — 96,247 For the three months ended June 30, 2014: Operating revenues $ 303,555 $ — $ 303,555 $ 9,475 $ (450 ) $ 312,580 Resource costs 128,922 — 128,922 — — 128,922 Other operating expenses 67,349 — 67,349 1,330 (450 ) 68,229 Depreciation and amortization 31,180 — 31,180 151 — 31,331 Income from operations 54,737 — 54,737 7,994 — 62,731 Interest expense (2) 18,422 — 18,422 316 (79 ) 18,659 Income taxes 13,302 — 13,302 3,389 — 16,691 Net income from continuing operations attributable to Avista Corp. shareholders 26,685 — 26,685 4,490 79 31,254 Capital expenditures (3) 76,789 — 76,789 56 — 76,845 For the six months ended June 30, 2015: Operating revenues $ 744,781 $ 23,006 $ 767,787 $ 16,585 $ (550 ) $ 783,822 Resource costs 344,556 6,120 350,676 — — 350,676 Other operating expenses 140,757 5,527 146,284 17,012 (550 ) 162,746 Depreciation and amortization 67,348 2,628 69,976 334 — 70,310 Income (loss) from operations 140,203 7,493 147,696 (761 ) — 146,935 Interest expense (2) 37,937 1,799 39,736 311 (52 ) 39,995 Income taxes 39,520 2,275 41,795 (532 ) — 41,263 Net income (loss) from continuing operations attributable to Avista Corp. shareholders 68,862 3,559 72,421 (922 ) — 71,499 Capital expenditures (3) 172,012 5,740 177,752 504 — 178,256 Avista Utilities Alaska Electric Light and Power Company Total Utility Other Intersegment Eliminations (1) Total For the six months ended June 30, 2014: Operating revenues $ 741,129 $ — $ 741,129 $ 18,929 $ (900 ) $ 759,158 Resource costs 349,419 — 349,419 — — 349,419 Other operating expenses 134,686 — 134,686 11,163 (900 ) 144,949 Depreciation and amortization 61,906 — 61,906 298 — 62,204 Income from operations 145,605 — 145,605 7,468 — 153,073 Interest expense (2) 36,968 — 36,968 713 (167 ) 37,514 Income taxes 40,922 — 40,922 3,051 — 43,973 Net income from continuing operations attributable to Avista Corp. shareholders 74,681 — 74,681 3,882 167 78,730 Capital expenditures (3) 136,514 — 136,514 102 — 136,616 Total Assets: As of June 30, 2015: $ 4,361,550 $ 268,607 $ 4,630,157 $ 49,832 $ — $ 4,679,989 As of December 31, 2014: $ 4,367,926 $ 264,195 $ 4,632,121 $ 80,210 $ — $ 4,712,331 (1) Intersegment eliminations reported as operating revenues and resource costs represent intercompany purchases and sales of electric capacity and energy. Intersegment eliminations reported as interest expense and net income (loss) attributable to Avista Corp. shareholders represent intercompany interest. (2) Including interest expense to affiliated trusts. (3) The capital expenditures for the other businesses are included as other capital expenditures on the Condensed Consolidated Statements of Cash Flows. The remainder of the balance included in other capital expenditures on the Condensed Consolidated Statements of Cash Flows in 2014 are related to Ecova.

Summary Of Significant Accoun23

Summary Of Significant Accounting Policies (Policy)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Nature Of Business	Nature of Business Avista Corp. is primarily an electric and natural gas utility with certain other business ventures. Avista Utilities is an operating division of Avista Corp., comprising the 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 Avista Utilities' Noxon Rapids generating facility. On July 1, 2014, Avista Corp. acquired Alaska Energy and Resources Company (AERC), and as of that date, AERC is a wholly-owned subsidiary of Avista Corp. The primary subsidiary of AERC is Alaska Electric Light and Power Company (AEL&P), comprising the regulated utility operations in Alaska. There are no AERC earnings included in the overall results of Avista Corp. in the first half of 2014. See Note 3 for information regarding the acquisition of AERC. Avista Capital, Inc. (Avista Capital), a wholly owned subsidiary of Avista Corp., is the parent company of all of the subsidiary companies in the non-utility businesses, except Spokane Energy, LLC (Spokane Energy). During the first half of 2014, Avista Capital’s subsidiaries included Ecova, Inc. (Ecova), which was an 80.2 percent owned subsidiary prior to its disposition on June 30, 2014. Ecova was a provider of energy efficiency and other facility information and cost management programs and services for multi-site customers and utilities throughout North America. See Note 4 for information regarding the disposition of Ecova and Note 14 for business segment information.
Basis Of Reporting	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. Ecova's revenues and expenses are included in the Condensed Consolidated Statements of Income in discontinued operations; however, as of June 30, 2014 and for all subsequent reporting periods there are no balance sheet amounts included for Ecova. All tables throughout the Notes to Condensed Consolidated Financial Statements that present Condensed Consolidated Statements of Income information were revised to include only the amounts from continuing operations. 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.
Taxes Other Than Income Taxes	Taxes Other Than Income Taxes Taxes other than income taxes include state excise taxes, city occupational and franchise taxes, real and personal property taxes and certain other taxes not based on net income. These taxes are generally based on revenues or the value of property. Utility related taxes collected from customers (primarily state excise taxes and city utility taxes) are recorded as operating revenue and expense and totaled the following amounts for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Utility taxes $ 12,941 $ 12,469 $ 32,439 $ 32,207
Other Income - Net	Other Income-Net Other income-net consisted of the following items for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Interest income $ 117 $ 250 $ 360 $ 524 Interest income on regulatory deferrals 14 51 34 95 Equity-related AFUDC 1,659 2,203 3,874 4,237 Net gain (loss) on investments (67 ) 185 (451 ) 145 Other income 113 366 250 654 Total $ 1,836 $ 3,055 $ 4,067 $ 5,655
Materials And Supplies, Fuel Stock And Natural Gas Stored	Materials and Supplies, Fuel Stock and Natural Gas Stored Inventories of materials and supplies, fuel stock and natural gas stored 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 June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Materials and supplies $ 35,056 $ 32,483 Fuel stock 5,714 5,142 Natural gas stored 10,103 28,731 Total $ 50,873 $ 66,356
Investments And Funds Held For Clients And Client Fund Obligations	Investments and Funds Held for Clients and Client Fund Obligations In connection with its bill paying services, Ecova collected funds from its clients and remitted the funds to the appropriate utility or other service provider. Some of the funds collected were invested by Ecova and classified as investments and funds held for clients, and a related liability for client fund obligations was recorded. Investments and funds held for clients included cash and cash equivalent investments, money market funds and investment securities classified as available for sale. Ecova did not invest the funds directly for the clients' benefit; therefore, Ecova bore the risk of loss associated with the investments. As of June 30, 2014 and for all subsequent reporting periods there are no longer any investments and funds held for clients due to the disposition of Ecova. The following is a summary of the disposition of available-for-sale securities for the three and six months ended June 30 , 2014 (dollars in thousands): Three months ended June 30, 2014 Six months ended June 30, 2014 Proceeds from sales, maturities and calls $ 3,209 $ 14,612 Gross realized gains — 3 Gross realized losses (1) (735 ) (735 )
Derivative Assets And Liabilities	Derivative Assets and Liabilities Derivatives are recorded as either assets or liabilities on the Condensed Consolidated Balance Sheets measured at estimated fair value. In certain defined conditions, a derivative may be specifically designated as a hedge for a particular exposure. The accounting for a derivative depends on the intended use of such derivative and the resulting designation. The Washington Utilities and Transportation Commission (UTC) and the Idaho Public Utilities Commission (IPUC) issued accounting orders authorizing Avista Utilities 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. The orders provide for Avista Utilities to not recognize the unrealized gain or loss on utility derivative commodity instruments in the Condensed Consolidated Statements of Income. Realized gains or losses are recognized in the periods of delivery, subject to approval for recovery through retail rates. Realized gains and losses, subject to regulatory approval, result in adjustments to retail rates through purchased gas cost adjustments, the Energy Recovery Mechanism (ERM) in Washington, the Power Cost Adjustment (PCA) mechanism in Idaho, and periodic general rates cases. Regulatory assets are assessed regularly and are probable for 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 agreements, each period Avista Utilities records all mark-to-market gains and losses as assets and liabilities and records offsetting regulatory assets and liabilities, such that there is no income statement impact. Upon settlement of interest rate swaps, the regulatory asset or liability (included as part of long-term debt) is amortized as a component of interest expense over the term of the associated debt.
Fair Value Measurements	Fair Value Measurements Fair value represents the price that would be received to sell 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 swap agreements 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.
Regulatory Deferred Charges And Credits	Regulatory Deferred Charges and Credits The Company follows the accounting practices for regulated operations for its regulated utility businesses because: • rates for regulated services are established by or subject to approval by independent third-party regulators, • the regulated rates are designed to recover the cost of providing the regulated services, and • in view of demand for the regulated services and the level of competition, it is reasonable to assume that rates can be charged to and collected from customers at levels that will recover costs. Regulatory accounting practices require that certain costs and/or obligations (such as incurred power and natural gas costs not currently included in rates, but expected to be recovered or refunded in the future) are reflected as deferred charges or credits on the Condensed Consolidated Balance Sheets. These costs and/or obligations are not reflected in the Condensed Consolidated Statements of Income until the period during which matching revenues are recognized. The Company also has decoupling revenue deferrals. As opposed to cost deferrals which are not recognized in the Condensed Consolidated Statements of Income until they are included in rates, decoupling revenue is recognized in the Condensed Consolidated Statements of Income during the period it occurs (i.e. during the period of revenue shortfall or excess due to fluctuations in customer usage) and a regulatory asset/liability is established which will be surcharged or rebated to customers in future periods. If at some point in the future the Company determines that it no longer meets the criteria for continued application of regulatory accounting practices for all or a portion of its regulated operations, the Company could be: • required to write off its regulatory assets, • precluded from the future deferral of costs or decoupled revenues not recovered through rates at the time such amounts are incurred, even if the Company expected to recover these amounts from customers in the future.
Contingencies	Contingencies The Company has unresolved regulatory, legal and tax issues which have inherently uncertain outcomes. The Company accrues a loss contingency if it is probable that a liability has been incurred and the amount of the loss or impairment can be reasonably estimated. The Company also discloses losses that do not meet these conditions for accrual, if there is a reasonable possibility that a loss may be incurred. As of June 30, 2015 , the Company has not recorded any significant amounts related to unresolved contingencies.
Reclassification, Policy	Reclassifications Certain prior year amounts on the Company's Condensed Consolidated Statements of Cash Flows were reclassified to conform to the current year presentation. In the current year Condensed Consolidated Statements of Cash Flows, "Decrease (increase) in collateral posted for derivative instruments," and "Income taxes receivable," were added as their own line items. These were previously included in "Other current assets" in the operating activities section.
Stockholders' Equity, Policy	Accumulated Other Comprehensive Loss Accumulated other comprehensive loss, net of tax, consisted of the following as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $(3,983) and $(4,247), respectively $ (7,397 ) $ (7,888 ) The following table details the reclassifications out of accumulated other comprehensive loss by component for the three and six months ended June 30 (dollars in thousands). Items in parenthesis indicate reductions to net income. Amounts Reclassified from Accumulated Other Comprehensive Loss Three months ended June 30, Six months ended June 30, Details about Accumulated Other Comprehensive Loss Components 2015 2014 2015 2014 Affected Line Item in Statement of Income Realized gains on investment securities $ — $ — $ — $ 3 (a) Realized losses on investment securities — (735 ) — (735 ) (a) — (735 ) — (732 ) Total before tax — 273 — 272 Tax expense (a) $ — $ (462 ) $ — $ (460 ) Net of tax Amortization of defined benefit pension items Amortization of net prior service cost $ 273 $ 38 $ 546 $ 76 (b) Amortization of net loss (3,687 ) (1,990 ) $ (7,375 ) $ (3,980 ) (b) Adjustment due to effects of regulation 3,037 1,778 6,074 3,560 (b) (377 ) (174 ) (755 ) (344 ) Total before tax 132 62 264 121 Tax benefit $ (245 ) $ (112 ) $ (491 ) $ (223 ) Net of tax (a) These amounts were included as part of net income from discontinued operations (see Note 4 for additional details). (b) These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 7 for additional details). Appropriated Retained Earnings In accordance with the hydroelectric licensing requirements of section 10(d) of the Federal Power Act (FPA), the Company maintains an appropriated retained earnings account for any earnings in excess of the specified rate of return on the Company's investment in the licenses for its various hydroelectric projects. The rate of return on investment is specified in the various hydroelectric licensing agreements for the Clark Fork River and Spokane River. Per section 10(d) of the FPA, the Company must maintain these excess earnings in an appropriated retained earnings account until the termination of the licensing agreements or apply them to reduce the net investment in the licenses of the hydroelectric projects at the discretion of the FERC. The Company typically calculates the earnings in excess of the specified rate of return on an annual basis, usually during the second quarter. In addition to the hydroelectric project licenses identified above for Avista Utilities, the requirements of section 10(d) of the FPA also apply to the AEL&P licenses for Lake Dorothy and Annex Creek/Salmon Creek (combined). The appropriated retained earnings amounts included in retained earnings were as follows as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Appropriated retained earnings $ 21,030 $ 14,270 Dividends The payment of dividends on common stock could be limited by: • certain covenants applicable to preferred stock (when outstanding) contained in the Company’s Restated Articles of Incorporation, as amended (currently there are no preferred shares outstanding), • certain covenants applicable to the Company's outstanding long-term debt and committed line of credit agreements, • the hydroelectric licensing requirements of section 10(d) of the FPA, and • certain requirements under the Public Utility Commission of Oregon (OPUC) approval of the AERC acquisition. After July 1, 2015 (one year following the acquisition date), the OPUC does not permit one-time or special dividends from AERC to Avista Corp. and does not permit Avista Utilities' total equity to total capitalization to be less than 40 percent , without approval from the OPUC. However, the OPUC approval does allow for regular distributions of AERC earnings to Avista Corp. as long as AERC remains sufficiently capitalized and insured. Under the covenant applicable to the Company's committed line of credit agreement, which does not permit the ratio of “consolidated total debt” to “consolidated total capitalization” to be greater than 65 percent at any time, the amount of retained earnings available for dividends at June 30, 2015 was limited to approximately $410.5 million . Under the requirements of the OPUC approval of the AERC acquisition as outlined above, the amount available for dividends at June 30, 2015 was limited to approximately $272.0 million . Stock Repurchase Program On December 16, 2014, the Company announced that Avista Corp.'s Board of Directors approved the repurchase of up to 800,000 shares of the Company’s outstanding common stock, commencing on January 2, 2015, and expiring on March 31, 2015 (first quarter 2015 program). The number of shares repurchased through the first quarter 2015 program were in addition to the number of shares repurchased during 2014 under a separate stock repurchase program, which expired on December 31, 2014. The parameters of the first quarter 2015 program were consistent with the parameters of the 2014 program. Under the first quarter 2015 program, the Company repurchased 89,400 shares at a total cost of $2.9 million and an average cost of $32.66 per share. All repurchased shares reverted to the status of authorized but unissued shares.

Summary Of Significant Accoun24

Summary Of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	Accumulated other comprehensive loss, net of tax, consisted of the following as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Unfunded benefit obligation for pensions and other postretirement benefit plans - net of taxes of $(3,983) and $(4,247), respectively $ (7,397 ) $ (7,888 )
Reclassifications Out of Accumulated Other Comprehensive Loss by Component	The following table details the reclassifications out of accumulated other comprehensive loss by component for the three and six months ended June 30 (dollars in thousands). Items in parenthesis indicate reductions to net income. Amounts Reclassified from Accumulated Other Comprehensive Loss Three months ended June 30, Six months ended June 30, Details about Accumulated Other Comprehensive Loss Components 2015 2014 2015 2014 Affected Line Item in Statement of Income Realized gains on investment securities $ — $ — $ — $ 3 (a) Realized losses on investment securities — (735 ) — (735 ) (a) — (735 ) — (732 ) Total before tax — 273 — 272 Tax expense (a) $ — $ (462 ) $ — $ (460 ) Net of tax Amortization of defined benefit pension items Amortization of net prior service cost $ 273 $ 38 $ 546 $ 76 (b) Amortization of net loss (3,687 ) (1,990 ) $ (7,375 ) $ (3,980 ) (b) Adjustment due to effects of regulation 3,037 1,778 6,074 3,560 (b) (377 ) (174 ) (755 ) (344 ) Total before tax 132 62 264 121 Tax benefit $ (245 ) $ (112 ) $ (491 ) $ (223 ) Net of tax (a) These amounts were included as part of net income from discontinued operations (see Note 4 for additional details). (b) These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 7 for additional details).
Utility Taxes	Utility related taxes collected from customers (primarily state excise taxes and city utility taxes) are recorded as operating revenue and expense and totaled the following amounts for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Utility taxes $ 12,941 $ 12,469 $ 32,439 $ 32,207
Other Income - Net	Other income-net consisted of the following items for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Interest income $ 117 $ 250 $ 360 $ 524 Interest income on regulatory deferrals 14 51 34 95 Equity-related AFUDC 1,659 2,203 3,874 4,237 Net gain (loss) on investments (67 ) 185 (451 ) 145 Other income 113 366 250 654 Total $ 1,836 $ 3,055 $ 4,067 $ 5,655
Materials And Supplies Fuel Stock And Natural Gas Stored	Inventories of materials and supplies, fuel stock and natural gas stored 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 June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Materials and supplies $ 35,056 $ 32,483 Fuel stock 5,714 5,142 Natural gas stored 10,103 28,731 Total $ 50,873 $ 66,356
Disposition of Available-for-Sale Securities	The following is a summary of the disposition of available-for-sale securities for the three and six months ended June 30 , 2014 (dollars in thousands): Three months ended June 30, 2014 Six months ended June 30, 2014 Proceeds from sales, maturities and calls $ 3,209 $ 14,612 Gross realized gains — 3 Gross realized losses (1) (735 ) (735 )
Appropriated Retained Earnings [Table Text Block]	The appropriated retained earnings amounts included in retained earnings were as follows as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Appropriated retained earnings $ 21,030 $ 14,270

Business Acquisitions (Tables)

Business Acquisitions (Tables)	6 Months Ended
	Jun. 30, 2015
Business Acquisition [Line Items]
Schedule of Business Acquisitions by Acquisition, Equity Interest Issued or Issuable [Table Text Block]	Contract acquisition price (using the calculated $32.46 per share common stock price) Gross contract price $ 170,000 Acquired cash 19,704 Acquired debt (excluding capital lease obligation) (38,832 ) Other closing adjustments (58 ) Total adjusted contract price $ 150,814 Fair value of consideration transferred Avista Corp. common stock (4,500,014 shares at $33.35 per share) $ 150,075 Avista Corp. common stock (1,427 shares at $30.71 per share) 44 Cash 4,792 Fair value of total consideration transferred $ 154,911
Business Acquisition, Pro Forma Information [Table Text Block]	Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Actual Pro forma Actual Pro forma Actual Avista Corp. revenues from continuing operations (excluding AERC) $ 327,085 $ 312,580 $ 760,784 $ 759,158 Supplemental pro forma AERC revenues (1) 10,247 11,782 23,038 24,546 Total pro forma revenues 337,332 324,362 783,822 783,704 Actual AERC revenues included in Avista Corp. revenues (1) 10,247 — 23,038 — Actual Avista Corp. net income from continuing operations attributable to Avista Corp. shareholders (excluding AERC) 24,222 31,254 68,140 78,730 Actual Avista Corp. net income from discontinued operations attributable to Avista Corp. shareholders 196 69,617 196 70,640 Adjustment to Avista Corp.'s net income for acquisition costs (net of tax) (2) 16 219 21 672 Supplemental pro forma AERC net income (1) 828 2,371 3,359 5,627 Total pro forma net income 25,262 103,461 71,716 155,669 Actual AERC net income included in Avista Corp. net income (1) $ 828 $ — $ 3,359 $ —

Discontinued Operations Disco26

Discontinued Operations Discontinued Operations (Tables)	6 Months Ended
	Jun. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block]	The following table presents amounts that were included in discontinued operations for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Revenues $ — $ 43,150 $ — $ 87,534 Gain on sale of Ecova (1) 163 161,100 163 161,100 Transaction expenses and accelerated employee benefits (2) — 8,976 — 8,976 Gain on sale of Ecova, net of transaction expenses 163 152,124 163 152,124 Income before income taxes 163 154,190 163 156,599 Income tax expense (benefit) (3) (33 ) 84,878 (33 ) 85,772 Net income from discontinued operations 196 69,312 196 70,827 Net income attributable to noncontrolling interests — 305 — (187 ) Net income from discontinued operations attributable to Avista Corp. shareholders $ 196 $ 69,617 $ 196 $ 70,640

Derivatives And Risk Manageme27

Derivatives And Risk Management (Tables)	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedges, Assets [Abstract]
Energy Commodity Derivatives	The following table presents the underlying energy commodity derivative volumes as of June 30, 2015 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) Financial (1) Physical (1) Financial (1) 2015 165 1,391 10,559 95,498 152 2,177 1,730 66,515 2016 394 1,348 2,505 97,058 287 2,116 1,370 74,668 2017 397 — 675 33,913 286 483 1,360 17,403 2018 397 — — 6,795 286 — 1,360 — 2019 235 — — 4,050 158 — 1,345 — Thereafter — — — — — — 2,470 — (1)
Foreign Currency Exchange Contracts	The following table summarizes the foreign currency hedges that the Company has outstanding as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Number of contracts 26 18 Notional amount (in United States currency) $ 8,183 $ 5,474 Notional amount (in Canadian currency) 10,130 6,198
Interest Rate Swap Agreements	The following table summarizes the interest rate swaps that the Company has entered into as of June 30, 2015 and December 31, 2014 (dollars in thousands): Balance Sheet Date Number of Contracts Notional Amount Mandatory Cash Settlement Date June 30, 2015 5 75,000 2015 6 115,000 2016 3 45,000 2017 11 245,000 2018 1 20,000 2019 December 31, 2014 5 75,000 2015 5 95,000 2016 3 45,000 2017 9 205,000 2018
Derivative Instruments Summary	The following table presents the fair values and locations of derivative instruments recorded on the Condensed Consolidated Balance Sheet as of June 30, 2015 (in thousands): Fair Value Derivative Balance Sheet Location Gross Asset Gross Liability Collateral Netting Net Asset (Liability) in Balance Sheet Foreign currency contracts Other current liabilities $ 4 $ (74 ) $ — $ (70 ) Interest rate contracts Other current assets 1,781 (325 ) — 1,456 Interest rate contracts Other property and investments-net 250 — — 250 Interest rate contracts Other current liabilities — (5,715 ) — (5,715 ) Interest rate contracts Other non-current liabilities and deferred credits 7,589 (53,364 ) 22,400 (23,375 ) Commodity contracts Current utility energy commodity derivative assets 544 (60 ) — 484 Commodity contracts Current utility energy commodity derivative liabilities 51,995 (73,946 ) 9,270 (12,681 ) Commodity contracts Other non-current liabilities and deferred credits 20,190 (48,404 ) 7,092 (21,122 ) Total derivative instruments recorded on the balance sheet $ 82,353 $ (181,888 ) $ 38,762 $ (60,773 ) The following table presents the fair values and locations of derivative instruments recorded on the Condensed Consolidated Balance Sheet as of December 31, 2014 (in thousands): Fair Value Derivative Balance Sheet Location Gross Asset Gross Liability Collateral Netting Net Asset (Liability) in Balance Sheet Foreign currency contracts Other current liabilities $ 1 $ (21 ) $ — $ (20 ) Interest rate contracts Other current assets 966 (506 ) — 460 Interest rate contracts Other current liabilities — (7,325 ) — (7,325 ) Interest rate contracts Other non-current liabilities and deferred credits — (69,737 ) 28,880 (40,857 ) Commodity contracts Current utility energy commodity derivative assets 2,063 (538 ) — 1,525 Commodity contracts Current utility energy commodity derivative liabilities 66,421 (97,586 ) 13,120 (18,045 ) Commodity contracts Other non-current liabilities and deferred credits 29,594 (54,077 ) 2,390 (22,093 ) Total derivative instruments recorded on the balance sheet $ 99,045 $ (229,790 ) $ 44,390 $ (86,355 )
Schedule of Assets Pledged as Collateral and Related Offsets [Table Text Block]	The following table presents the Company's collateral outstanding related to its derivative instruments as of June 30, 2015 and December 31, 2014 (in thousands): June 30, December 31, 2015 2014 Energy commodity derivatives Cash collateral posted $ 27,953 $ 20,565 Letters of credit outstanding 20,000 14,500 Balance sheet offsetting (cash collateral against net derivative positions) 16,362 15,510 Interest rate swaps Cash collateral posted 22,400 28,880 Letters of credit outstanding 7,200 10,900 Balance sheet offsetting (cash collateral against net derivative positions) 22,400 28,880 Certain of the Company’s derivative instruments contain provisions that require the Company to maintain an "investment grade" credit rating from the major credit rating agencies. If the Company’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 the Company could be required to post as of June 30, 2015 and December 31, 2014 (in thousands): June 30, December 31, 2015 2014 Liabilities with credit-risk-related contingent features $ 6,684 $ 12,911 Additional collateral to post 6,682 16,227

Asset Retirement Obligations 28

Asset Retirement Obligations Asset Retirement Obligations (Tables)	6 Months Ended
	Jun. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Asset Retirement Obligations [Table Text Block]	The following table documents the changes in the Company’s asset retirement obligation for the period December 31, 2014 through June 30, 2015 (dollars in thousands): 2015 Asset retirement obligation at December 31, 2014 $ 3,028 Liabilities incurred 11,658 Liabilities settled (6 ) Accretion expense 111 Asset retirement obligation at June 30, 2015 $ 14,791

Pension Plans And Other Postr29

Pension Plans And Other Postretirement Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2015
Components of Net Periodic Benefit Cost	Pension Benefits Other Post-retirement Benefits 2015 2014 2015 2014 Three months ended June 30: Service cost $ 4,984 $ 3,868 $ 721 $ 499 Interest cost 6,531 6,706 1,292 1,353 Expected return on plan assets (7,075 ) (8,110 ) (500 ) (472 ) Amortization of prior service cost 6 6 (287 ) (43 ) Net loss recognition 2,634 14 1,263 349 Net periodic benefit cost $ 7,080 $ 2,484 $ 2,489 $ 1,686 Six months ended June 30: Service cost $ 9,933 $ 8,886 $ 1,420 $ 1,473 Interest cost 13,203 13,412 2,623 2,706 Expected return on plan assets (14,491 ) (16,220 ) (931 ) (944 ) Amortization of prior service cost 12 12 (566 ) (86 ) Net loss recognition 5,028 1,171 2,555 1,175 Net periodic benefit cost $ 13,685 $ 7,261 $ 5,101 $ 4,324

Committed Lines of Credit (Tabl

Committed Lines of Credit (Tables)	6 Months Ended
	Jun. 30, 2015
Short-term Debt [Abstract]
Schedule of Line of Credit Facilities [Table Text Block]	Balances outstanding and interest rates of borrowings (excluding letters of credit) under the Company’s revolving committed lines of credit were as follows as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, December 31, 2015 2014 Borrowings outstanding at end of period $ 90,000 $ 105,000 Letters of credit outstanding at end of period $ 34,379 $ 32,579 Average interest rate on borrowings at end of period 0.94 % 0.93 %

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2015
Long-term Debt, Unclassified [Abstract]
Schedule of Capital Leased Assets [Table Text Block]	The balances related to the Snettisham capital lease obligation as of June 30, 2015 and December 31, 2014 were as follows (dollars in thousands): June 30, December 31, 2015 2014 Capital lease obligation (1) $ 68,840 $ 69,955 Capital lease asset (2) 71,007 71,007 Accumulated amortization of capital lease asset (2) 3,641 1,821 (1) The capital lease obligation amount is equal to the amount of AIDEA's revenue bonds outstanding. (2) These amounts are included in utility plant in service on the Condensed Consolidated Balance Sheet. Interest on the capital lease obligation and amortization of the capital lease asset are included in utility resource costs in the Condensed Consolidated Statements of Income and totaled the following amounts for the three and six months ended June 30 (dollars in thousands): Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 Interest on capital lease obligation $ 922 $ — $ 1,845 $ — Amortization of capital lease asset 910 — 1,820 —
Schedule of Maturities of Long-term Debt [Table Text Block]	The following table details future capital lease obligations, including interest, under the Snettisham PPA (dollars in thousands): Remaining 2015 2016 2017 2018 2019 Thereafter Total Principal $ 1,115 $ 2,350 $ 2,480 $ 2,615 $ 2,755 $ 57,525 $ 68,840 Interest 1,845 3,567 3,438 3,305 3,165 25,364 40,684 Total $ 2,960 $ 5,917 $ 5,918 $ 5,920 $ 5,920 $ 82,889 $ 109,524
Long-term Debt Outstanding	Maturity Interest June 30, December 31, Year Description Rate 2015 2014 Avista Corp. Secured Long-Term Debt 2016 First Mortgage Bonds 0.84% $ 90,000 $ 90,000 2018 First Mortgage Bonds 5.95% 250,000 250,000 2018 Secured Medium-Term Notes 7.39%-7.45% 22,500 22,500 2019 First Mortgage Bonds 5.45% 90,000 90,000 2020 First Mortgage Bonds 3.89% 52,000 52,000 2022 First Mortgage Bonds 5.13% 250,000 250,000 2023 Secured Medium-Term Notes 7.18%-7.54% 13,500 13,500 2028 Secured Medium-Term Notes 6.37% 25,000 25,000 2032 Secured Pollution Control Bonds (1) (1) 66,700 66,700 2034 Secured Pollution Control Bonds (1) (1) 17,000 17,000 2035 First Mortgage Bonds 6.25% 150,000 150,000 2037 First Mortgage Bonds 5.70% 150,000 150,000 2040 First Mortgage Bonds 5.55% 35,000 35,000 2041 First Mortgage Bonds 4.45% 85,000 85,000 2044 First Mortgage Bonds 4.11% 60,000 60,000 2047 First Mortgage Bonds 4.23% 80,000 80,000 Total Avista Corp. secured long-term debt 1,436,700 1,436,700 Alaska Electric Light and Power Company Secured Long-Term Debt 2044 First Mortgage Bonds 4.54% 75,000 75,000 Total consolidated secured long-term debt 1,511,700 1,511,700 Alaska Energy and Resources Company Unsecured Long-Term Debt 2019 Unsecured Term Loan 3.85% 15,000 15,000 Total secured and unsecured long-term debt 1,526,700 1,526,700 Capital lease obligations 73,422 74,149 Settled interest rate swaps (2) (17,336 ) (17,541 ) Unamortized debt discount (1,039 ) (1,122 ) Total 1,581,747 1,582,186 Secured Pollution Control Bonds held by Avista Corporation (1) (83,700 ) (83,700 ) Current portion of long-term debt and capital leases (3,162 ) (6,424 ) Total long-term debt and capital leases $ 1,494,885 $ 1,492,062 (1) In December 2010, $66.7 million and $17.0 million of the City of Forsyth, Montana Pollution Control Revenue Refunding Bonds (Avista Corporation Colstrip Project) due in 2032 and 2034 , respectively, which had been held by Avista Corp. since 2008 and 2009, respectively, were refunded by new bond issues (Series 2010A and Series 2010B). The new bonds were not offered to the public and were purchased by Avista Corp. due to market conditions. The Company expects that at a later date, subject to market conditions, these bonds may be remarketed to unaffiliated investors. So long as Avista Corp. is the holder of these bonds, the bonds will not be reflected as an asset or a liability on Avista Corp.'s Condensed Consolidated Balance Sheets. (2) Upon settlement of interest rate swaps, these are recorded as a regulatory asset or liability and included as part of long-term debt above. They are amortized as a component of interest expense over the life of the associated debt and included as a part of the Company's cost of debt calculation for ratemaking purposes.

Long- Term Debt to Affiliated32

Long- Term Debt to Affiliated Trust Long-Term Debt to Affiliated Trust (Tables)	6 Months Ended
	Jun. 30, 2015
Long-Term Debt to Affiliated Trust [Abstract]
Schedule Of Distribution Rates Paid [Table Text Block]	The distribution rates paid were as follows during the six months ended June 30, 2015 and the year ended December 31, 2014 : June 30, December 31, 2015 2014 Low distribution rate 1.11 % 1.10 % High distribution rate 1.16 % 1.11 % Distribution rate at the end of the period 1.16 % 1.11 %

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair Value Inputs, Liabilities, Quantitative Information [Table Text Block]	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 June 30, 2015 (dollars in thousands): Fair Value (Net) at June 30, 2015 Valuation Technique Unobservable Input Range Power exchange agreement $ (18,616 ) Surrogate facility pricing O&M charges $30.66-$55.56/MWh (1) Escalation factor 3% - 2015 to 2019 Transaction volumes 392,608 - 397,030 MWhs Power option agreement (145 ) Black-Scholes- Merton Strike price $43.44/MWh - 2015 $55.66/MWh - 2019 Delivery volumes 128,278 - 287,147 MWhs Volatility rates 0.20 (2) Natural gas exchange agreement (6,825 ) Internally derived Forward purchase prices $2.27 - $3.19/mmBTU Forward sales prices $2.47 - $4.08/mmBTU Purchase volumes 125,000 - 310,000 mmBTUs Sales volumes 60,000 - 310,000 mmBTUs
Carrying Value and Estimated Fair Value of Financial Instruments	The following table sets forth the carrying value and estimated fair value of the Company’s financial instruments not reported at estimated fair value on the Condensed Consolidated Balance Sheets as of June 30, 2015 and December 31, 2014 (dollars in thousands): June 30, 2015 December 31, 2014 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value Long-term debt (Level 2) $ 951,000 $ 1,087,197 $ 951,000 $ 1,118,972 Long-term debt (Level 3) 492,000 496,848 492,000 527,663 Snettisham capital lease obligation (Level 3) 68,840 75,174 69,955 79,290 Nonrecourse long-term debt (Level 3) — — 1,431 1,440 Long-term debt to affiliated trusts (Level 3) 51,547 37,629 51,547 38,582
Fair Value of Assets And Liabilities Measured on Recurring Basis	Level 1 Level 2 Level 3 Counterparty Total June 30, 2015 Assets: Energy commodity derivatives $ — $ 72,728 $ — $ (72,244 ) $ 484 Level 3 energy commodity derivatives: Natural gas exchange agreement — — 1 (1 ) — Foreign currency derivatives — 4 — (4 ) — Interest rate swaps — 9,620 — (7,914 ) 1,706 Deferred compensation assets: Fixed income securities (2) 1,830 — — — 1,830 Equity securities (2) 6,199 — — — 6,199 Total $ 8,029 $ 82,352 $ 1 $ (80,163 ) $ 10,219 Liabilities: Energy commodity derivatives $ — $ 96,823 $ — $ (88,606 ) $ 8,217 Level 3 energy commodity derivatives: Natural gas exchange agreement — — 6,826 (1 ) 6,825 Power exchange agreement — — 18,616 — 18,616 Power option agreement — — 145 — 145 Foreign currency derivatives — 74 — (4 ) 70 Interest rate swaps — 59,404 — (30,314 ) 29,090 Total $ — $ 156,301 $ 25,587 $ (118,925 ) $ 62,963 Level 1 Level 2 Level 3 Counterparty Total December 31, 2014 Assets: Energy commodity derivatives $ — $ 96,729 $ — $ (95,204 ) $ 1,525 Level 3 energy commodity derivatives: Natural gas exchange agreement — — 1,349 (1,349 ) — Foreign currency derivatives — 1 — (1 ) — Interest rate swaps — 966 — (506 ) 460 Funds held in trust account of Spokane Energy 1,600 — — — 1,600 Deferred compensation assets: Fixed income securities (2) 1,793 — — — 1,793 Equity securities (2) 6,074 — — — 6,074 Total $ 9,467 $ 97,696 $ 1,349 $ (97,060 ) $ 11,452 Liabilities: Energy commodity derivatives $ — $ 127,094 $ — $ (110,714 ) $ 16,380 Level 3 energy commodity derivatives: Natural gas exchange agreement — — 1,384 (1,349 ) 35 Power exchange agreement — — 23,299 — 23,299 Power option agreement — — 424 — 424 Interest rate swaps — 77,568 — (29,386 ) 48,182 Foreign currency derivatives — 21 — (1 ) 20 Total $ — $ 204,683 $ 25,107 $ (141,450 ) $ 88,340 (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 trading securities and are included in other property and investments-net on the Condensed Consolidated Balance Sheets.
Reconciliation for All Assets Measured At Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3)	Natural Gas Exchange Agreement Power Exchange Agreement Power Option Agreement Total Three months ended June 30, 2015: Balance as of April 1, 2015 $ 817 $ (25,903 ) $ (251 ) $ (25,337 ) Total gains or losses (realized/unrealized): Included in net income — — — — Included in other comprehensive income — — — — Included in regulatory assets/liabilities (8,163 ) 6,551 106 (1,506 ) Purchases — — — — Issuance — — — — Settlements 521 736 — 1,257 Transfers to/from other categories — — — — Ending balance as of June 30, 2015 $ (6,825 ) $ (18,616 ) $ (145 ) $ (25,586 ) Three months ended June 30, 2014: Balance as of April 1, 2014 $ (2,418 ) $ (13,624 ) $ (428 ) $ (16,470 ) Total gains or losses (realized/unrealized): Included in net income — — — — Included in other comprehensive income — — — — Included in regulatory assets/liabilities 235 5,029 (177 ) 5,087 Purchases — — — — Issuance — — — — Settlements — 676 — 676 Transfers to/from other categories — — — — Ending balance as of June 30, 2014 $ (2,183 ) $ (7,919 ) $ (605 ) $ (10,707 ) Six months ended June 30, 2015: Balance as of January 1, 2015 $ (35 ) $ (23,299 ) $ (424 ) $ (23,758 ) Total gains or losses (realized/unrealized): Included in net income — — — — Included in other comprehensive income — — — — Included in regulatory assets/liabilities (7,386 ) 170 279 (6,937 ) Purchases — — — — Issuance — — — — Settlements 596 4,513 — 5,109 Transfers to/from other categories — — — — Ending balance as of June 30, 2015 $ (6,825 ) $ (18,616 ) $ (145 ) $ (25,586 ) Natural Gas Exchange Agreement Power Exchange Agreement Power Option Agreement Total Six months ended June 30, 2014: Balance as of January 1, 2014 $ (1,219 ) $ (14,441 ) $ (775 ) $ (16,435 ) Total gains or losses (realized/unrealized): Included in net income — — — — Included in other comprehensive income — — — — Included in regulatory assets/liabilities 2,084 7,055 170 9,309 Purchases — — — — Issuance — — — — Settlements (3,048 ) (533 ) — (3,581 ) Transfers from other categories — — — — Ending balance as of June 30, 2014 $ (2,183 ) $ (7,919 ) $ (605 ) $ (10,707 )

Earnings Per Common Share Att34

Earnings Per Common Share Attributable To Avista Corporation (Tables)	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Computations Of Earnings Per Share	Three months ended Six months ended June 30, June 30, 2015 2014 2015 2014 Numerator: Net income from continuing operations attributable to Avista Corp. shareholders $ 25,050 $ 31,254 $ 71,499 $ 78,730 Net income from discontinued operations attributable to Avista Corp. shareholders 196 69,617 196 70,640 Subsidiary earnings adjustment for dilutive securities (discontinued operations) — 58 — 5 Adjusted net income from discontinued operations attributable to Avista Corp. shareholders for computation of diluted earnings per common share $ 196 $ 69,675 $ 196 $ 70,645 Denominator: Weighted-average number of common shares outstanding-basic 62,281 60,184 62,299 60,153 Effect of dilutive securities: Performance and restricted stock awards 319 279 445 163 Weighted-average number of common shares outstanding-diluted 62,600 60,463 62,744 60,316 Earnings per common share attributable to Avista Corp. shareholders, basic: Earnings per common share from continuing operations $ 0.41 $ 0.52 $ 1.15 $ 1.31 Earnings per common share from discontinued operations $ — $ 1.16 $ — $ 1.17 Total earnings per common share attributable to Avista Corp. shareholders, basic $ 0.41 $ 1.68 $ 1.15 $ 2.48 Earnings per common share attributable to Avista Corp. shareholders, diluted: Earnings per common share from continuing operations $ 0.40 $ 0.52 $ 1.14 $ 1.31 Earnings per common share from discontinued operations $ — $ 1.15 $ — $ 1.17 Total earnings per common share attributable to Avista Corp. shareholders, diluted $ 0.40 $ 1.67 $ 1.14 $ 2.48 There were no shares excluded from the calculation because they were antidilutive.

Information By Business Segme35

Information By Business Segments (Tables)	6 Months Ended
	Jun. 30, 2015
Segment Reporting [Abstract]
Information by Business Segments	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 June 30, 2015: Operating revenues $ 320,698 $ 10,232 $ 330,930 $ 6,502 $ (100 ) $ 337,332 Resource costs 137,896 3,220 141,116 — — 141,116 Other operating expenses 70,348 2,764 73,112 6,746 (100 ) 79,758 Depreciation and amortization 34,351 1,325 35,676 165 — 35,841 Income (loss) from operations 55,415 2,354 57,769 (409 ) — 57,360 Interest expense (2) 18,969 895 19,864 147 (30 ) 19,981 Income taxes 14,632 591 15,223 (207 ) — 15,016 Net income (loss) from continuing operations attributable to Avista Corp. shareholders 24,478 925 25,403 (353 ) — 25,050 Capital expenditures (3) 90,800 5,355 96,155 92 — 96,247 For the three months ended June 30, 2014: Operating revenues $ 303,555 $ — $ 303,555 $ 9,475 $ (450 ) $ 312,580 Resource costs 128,922 — 128,922 — — 128,922 Other operating expenses 67,349 — 67,349 1,330 (450 ) 68,229 Depreciation and amortization 31,180 — 31,180 151 — 31,331 Income from operations 54,737 — 54,737 7,994 — 62,731 Interest expense (2) 18,422 — 18,422 316 (79 ) 18,659 Income taxes 13,302 — 13,302 3,389 — 16,691 Net income from continuing operations attributable to Avista Corp. shareholders 26,685 — 26,685 4,490 79 31,254 Capital expenditures (3) 76,789 — 76,789 56 — 76,845 For the six months ended June 30, 2015: Operating revenues $ 744,781 $ 23,006 $ 767,787 $ 16,585 $ (550 ) $ 783,822 Resource costs 344,556 6,120 350,676 — — 350,676 Other operating expenses 140,757 5,527 146,284 17,012 (550 ) 162,746 Depreciation and amortization 67,348 2,628 69,976 334 — 70,310 Income (loss) from operations 140,203 7,493 147,696 (761 ) — 146,935 Interest expense (2) 37,937 1,799 39,736 311 (52 ) 39,995 Income taxes 39,520 2,275 41,795 (532 ) — 41,263 Net income (loss) from continuing operations attributable to Avista Corp. shareholders 68,862 3,559 72,421 (922 ) — 71,499 Capital expenditures (3) 172,012 5,740 177,752 504 — 178,256 Avista Utilities Alaska Electric Light and Power Company Total Utility Other Intersegment Eliminations (1) Total For the six months ended June 30, 2014: Operating revenues $ 741,129 $ — $ 741,129 $ 18,929 $ (900 ) $ 759,158 Resource costs 349,419 — 349,419 — — 349,419 Other operating expenses 134,686 — 134,686 11,163 (900 ) 144,949 Depreciation and amortization 61,906 — 61,906 298 — 62,204 Income from operations 145,605 — 145,605 7,468 — 153,073 Interest expense (2) 36,968 — 36,968 713 (167 ) 37,514 Income taxes 40,922 — 40,922 3,051 — 43,973 Net income from continuing operations attributable to Avista Corp. shareholders 74,681 — 74,681 3,882 167 78,730 Capital expenditures (3) 136,514 — 136,514 102 — 136,616 Total Assets: As of June 30, 2015: $ 4,361,550 $ 268,607 $ 4,630,157 $ 49,832 $ — $ 4,679,989 As of December 31, 2014: $ 4,367,926 $ 264,195 $ 4,632,121 $ 80,210 $ — $ 4,712,331 (1) Intersegment eliminations reported as operating revenues and resource costs represent intercompany purchases and sales of electric capacity and energy. Intersegment eliminations reported as interest expense and net income (loss) attributable to Avista Corp. shareholders represent intercompany interest. (2) Including interest expense to affiliated trusts. (3) The capital expenditures for the other businesses are included as other capital expenditures on the Condensed Consolidated Statements of Cash Flows. The remainder of the balance included in other capital expenditures on the Condensed Consolidated Statements of Cash Flows in 2014 are related to Ecova.

Summary Of Significant Accoun36

Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 29, 2014
Summary Of Significant Accounting Policies [Line Items]
Maximum Dividends Allowed by Debt Covenants		$ 410,500
Sale and maturity of securities available for sale	$ 3,209	0	$ 14,612
Maximum Dividends Allowed by Regulator Approval		$ 272,000
Ecova [Member]
Summary Of Significant Accounting Policies [Line Items]
Owners percentage interest				80.20%
Avista Corporation [Member]
Summary Of Significant Accounting Policies [Line Items]
Line of Credit Facility, Covenant Terms		0.65

Summary Of Significant Accoun37

Summary Of Significant Accounting Policies (Utility Taxes) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accounting Policies [Abstract]
Utility taxes	$ 12,941	$ 12,469	$ 32,439	$ 32,207

Summary Of Significant Accoun38

Summary Of Significant Accounting Policies (Other Income - Net) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accounting Policies [Abstract]
Interest income	$ 117	$ 250	$ 360	$ 524
Interest on regulatory deferrals	14	51	34	95
Equity-related AFUDC	1,659	2,203	3,874	4,237
Net loss on investments	(67)	185	(451)	145
Other income	113	366	250	654
Total	$ 1,836	$ 3,055	$ 4,067	$ 5,655

Summary Of Significant Accoun39

Summary Of Significant Accounting Policies (Materials And Supplies Fuel Stock And Natural Gas Stored) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Materials and supplies	$ 35,056	$ 32,483
Fuel stock	5,714	5,142
Natural gas stored	10,103	28,731
Total	$ 50,873	$ 66,356

Summary Of Significant Accoun40

Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Available-for-Sale Securities) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Available-for-sale Securities [Abstract]
Proceeds from Sale of Available-for-sale Securities	$ 3,209	$ 0	$ 14,612
Available-for-sale Securities, Gross Realized Gains	0		3
Available-for-sale Securities, Gross Realized Losses	$ (735)		$ (735)

Summary Of Significant Accoun41

Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans Net Unamortized (Gain) Loss, Tax	$ (4,360)	$ (4,247)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(7,397)	(7,888)
Accumulated other comprehensive loss	$ (7,397)	$ (7,888)

Summary Of Significant Accoun42

Summary Of Significant Accounting Policies (Reclassifications Out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes		$ 163	$ 154,190	$ 163		$ 156,599
Income tax expense		33	(84,878)	33		(85,772)
Net income from discontinued operations		196	69,312	196		70,827
Tax expense (a)		(15,016)	(16,691)	(41,263)		(43,973)
Net income		25,274	100,582	71,736		149,563
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes		0	(735)	0		(732)
Income tax expense		0	273	0	[1]	272	[1]
Net income from discontinued operations		0	(462)	0		(460)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax		0	0	0	[1]	3	[1]
Other Comprehensive Loss Reclassification Adjustment From AOCI For Sale Of Securities Before Tax		0	(735)	0	[1]	(735)	[1]
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		(377)	(174)	(755)		(344)
Tax expense (a)		132	62	264		121
Net income		(245)	(112)	(491)		(223)
Amortization of net loss	[2]	273	38	546		76
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	[2]	(3,687)	(1,990)	(7,375)		(3,980)
Adjustment due to effects of regulation	[2]	$ 3,037	$ 1,778	$ 6,074		$ 3,560
[1]	These amounts were included as part of net income from discontinued operations (see Note 4 for additional details).
[2]	These accumulated other comprehensive loss components are included in the computation of net periodic pension cost (see Note 7 for additional details).

Summary Of Significant Accoun43

Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Appropriated Retained Earnings) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Equity [Abstract]
Retained Earnings, Appropriated	$ 21,030	$ 14,270

Summary Of Significant Accoun44

Summary Of Significant Accounting Policies Summary of Significant Accounting Policies (Stock Repurchase Program) (Details) - USD ($) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 16, 2014
Share Repurchase Program [Abstract]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased		800,000
Stock Repurchased During Period, Shares	89,400
Treasury Stock, Value, Acquired, Cost Method	$ 2.9
Treasury Stock Acquired, Average Cost Per Share	$ 32.66

Business Acquisitions (Details)

Business Acquisitions (Details) - Equity Interest Issued or Issuable, Type [Domain] $ / shares in Units, $ in Thousands	Oct. 01, 2014$ / sharesshares	Jul. 01, 2014USD ($)$ / sharesshares	Jun. 30, 2015USD ($)employee	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)employeedMW	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)employee	Dec. 31, 2014USD ($)
Business Acquisition [Line Items]
Goodwill			$ 57,672		$ 57,672		$ 57,672	$ 57,976
Business Acquisition, Share Price | $ / shares	$ 30.71	$ 33.35
Operating revenues			337,332	$ 312,580	$ 783,822	$ 759,158
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	1,427	4,500,014
Business Combination Equity Consideration Share Price | $ / shares		$ 32.46
Business Combination Number of Trading Days to Price Equity Consideration Share Price | d					10
Merger Consideration - Total		$ 170,000
Representative Reimbursement Amount							4,792
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		19,704
Business Acquisition Recognized Identifiable Assets Acquired and Liabilities Assumed Current and Long-Term Debt		38,832
Business Acquisition Contract Price Closing Adjustments		58
Business Acquisition Adjusted Contract Price		150,814
Business Combination, Consideration Transferred		$ 154,911
Alaska Energy Resources Company [Member]
Business Acquisition [Line Items]
Operating revenues			10,247	$ 11,782	$ 23,038	$ 24,546
Alaska Electric Light & Power [Member]
Business Acquisition [Line Items]
Goodwill, Purchase Accounting Adjustments					(300)
Goodwill			$ 52,400		$ 52,400		$ 52,400
Number of Customers | employee			16,552		16,552		16,552
Alaska Electric Light & Power [Member] | Power purchase agreement [Member]
Business Acquisition [Line Items]
Evaluated Power Capacity | MW					78

Business Acquisitions Contract

Business Acquisitions Contract Price and Fair Value of Consideration Transferred (Details) - USD ($) $ in Thousands	Oct. 01, 2014	Jul. 01, 2014	Jun. 30, 2015
Business Acquisition [Line Items]
Merger Consideration - Total		$ 170,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		19,704
Business Acquisition Recognized Identifiable Assets Acquired and Liabilities Assumed Current and Long-Term Debt		(38,832)
Business Acquisition Contract Price Closing Adjustments		(58)
Business Acquisition Adjusted Contract Price		150,814
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 44	150,075
Payments to Acquire Businesses, Gross			$ 4,792
Business Combination, Consideration Transferred		$ 154,911

Business Acquisitions Pro Forma

Business Acquisitions Pro Forma Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		24 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015
Business Acquisition [Line Items]
Revenues Excluding Acquired Entity	$ 327,085	$ 312,580	$ 760,784	$ 759,158
Supplemental Pro Forma Revenues	337,332	312,580	783,822	759,158
Business Acquisition, Pro Forma Revenue	337,332	324,362	783,822	783,704
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	10,247	0	23,038	0
Income (Loss) from Continuing Operations Attributable to Parent	24,222	31,254	68,140	78,730
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	196	69,617	196	70,640
Net income attributable to Avista Corporation shareholders	25,246	100,871	71,695	149,370
Business Acquisition, Pro Forma Net Income (Loss)	25,262	103,461	71,716	155,669
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual	828	0	3,359	0
Alaska Energy Resources Company [Member]
Business Acquisition [Line Items]
Supplemental Pro Forma Revenues	10,247	11,782	23,038	24,546
Net income attributable to Avista Corporation shareholders	828	2,371	3,359	5,627
Avista Utilities [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs					$ 3,000
Avista Utilities [Member] | Acquisition-related Costs [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs	$ 16	$ 219	$ 21	$ 672
Acquisition-related Costs [Member] | Avista Utilities [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs					$ 400

Discontinued Operations Summary

Discontinued Operations Summary of Cash Proceeds from Sale of Discontinued Operations (Details) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2015USD ($)mo	Jun. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contract price		$ 335,000
Repayment of long-term borrowings under committed line of credit	$ 0	$ (46,000)
Transaction expenses withheld from proceeds			$ (5,400)
Total net proceeds related to sales transaction			143,700
Number of Months Receivable Held in Escrow | mo	15
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax			$ 69,900
Indemnification Agreement [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Escrow Receivable	$ 16,800
Escrow Percentage of Contract Price	5.00%
Working Capital Escrow Adjustment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Escrow Receivable	$ 1,000

Discontinued Operations Summa49

Discontinued Operations Summary of Income Statement Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax					$ 69,900
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ 196	$ 69,617	$ 196	$ 70,640
Transaction expenses withheld from proceeds					(5,400)
Revenues	0	43,150	0	87,534
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax	163	161,100	163	161,100
Transaction expenses and accelerated employee benefits (2)					11,000
Discontinued Operation Gain Loss From Disposal Of Discontinued Operation Before Income Taxes Net of Transaction Costs	163	152,124	163	152,124
Income before income taxes	163	154,190	163	156,599
Income tax expense (benefit)	(33)	84,878	(33)	85,772
Net income from discontinued operations	196	69,312	196	70,827
Net income attributable to noncontrolling interests	(28)	289	(41)	(193)
Ecova [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transaction expenses and accelerated employee benefits (2)	0	8,976	0	8,976	$ 9,100
Net income attributable to noncontrolling interests	$ 0	$ (305)	$ 0	$ (187)

Derivatives And Risk Manageme50

Derivatives And Risk Management (Narrative) (Details) - Long-term Debt, Type [Domain] - Debt Instrument, Name [Domain] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Secured Debt	$ 1,511,700	$ 1,511,700
Derivative, Fair Value, Amount Offset Against Collateral, Net	38,762	44,390
Liability position at aggregate fair value	6,684	12,911
Additional Collateral, Aggregate Fair Value	6,682	16,227
Commodity Contracts [Member]
Derivative [Line Items]
Cash deposited as collateral	27,953	20,565
Letters of credit outstanding	20,000	14,500
Derivative, Fair Value, Amount Offset Against Collateral, Net	16,362	15,510
Interest Rate Swap [Member]
Derivative [Line Items]
Cash deposited as collateral	22,400	28,880
Letters of credit outstanding	7,200	10,900
Derivative, Fair Value, Amount Offset Against Collateral, Net	$ 22,400	$ 28,880

Derivatives And Risk Manageme51

Derivatives And Risk Management (Energy Commodity Derivatives) (Details) - 6 months ended Jun. 30, 2015 frequency in Thousands, Volt in Thousands		Voltfrequency
Sales [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2,015	[1]	152
2,016	[1]	287
2,017	[1]	286
2,018	[1]	286
2,019	[1]	158
Thereafter	[1]	0
Sales [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2015 | Volt	[1]	1,730
2016 | Volt	[1]	1,370
2017 | Volt	[1]	1,360
2,018	[1]	1,360
2,019	[1]	1,345
Thereafter | Volt	[1]	2,470
Sales [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2,015	[1]	2,177
2,016	[1]	2,116
2,017	[1]	483
2,018	[1]	0
2,019	[1]	0
Thereafter	[1]	0
Sales [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2015 | Volt	[1]	66,515
2016 | Volt	[1]	74,668
2017 | Volt	[1]	17,403
2018 | Volt	[1]	0
2,019	[1]	0
Thereafter | Volt	[1]	0
Purchase [Member] | Physical [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2,015	[1]	165
2,016	[1]	394
2,017	[1]	397
2,018	[1]	397
2,019	[1]	235
Thereafter	[1]	0
Purchase [Member] | Physical [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2015 | Volt	[1]	10,559
2016 | Volt	[1]	2,505
2017 | Volt	[1]	675
2018 | Volt	[1]	0
2019 | Volt	[1]	0
Thereafter | Volt	[1]	0
Purchase [Member] | Financial [Member] | Electric Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2,015	[1]	1,391
2,016	[1]	1,348
2,017	[1]	0
2,018	[1]	0
2,019	[1]	0
Thereafter	[1]	0
Purchase [Member] | Financial [Member] | Gas Derivative [Member]
Energy Commodity Derivative Volumes [Line Items]
2015 | Volt	[1]	95,498
2016 | Volt	[1]	97,058
2017 | Volt	[1]	33,913
2018 | Volt	[1]	6,795
2019 | Volt	[1]	4,050
Thereafter | Volt	[1]	0
[1]	Physical transactions represent commodity transactions in which Avista Utilities will take or make delivery of either electricity or natural gas; financial transactions represent derivative instruments with delivery of cash in the amount of gain or loss but with no physical delivery of the commodity, such as futures, swaps, options, or forward contracts.

Derivatives And Risk Manageme52

Derivatives And Risk Management (Interest Rate Swap Agreements) (Details) - Debt Instrument, Name [Domain] - Long-term Debt, Type [Domain] $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015USD ($)Caontracts	Dec. 31, 2014USD ($)Caontracts
Derivatives, Fair Value [Line Items]
Secured Debt	$ 1,511,700	$ 1,511,700
2015 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	5	5
Derivative, Notional Amount	$ 75,000	$ 75,000
Derivative, Maturity Date	Dec. 31, 2015	Dec. 31, 2015
2016 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	6	5
Derivative, Notional Amount	$ 115,000	$ 95,000
Derivative, Maturity Date	Dec. 31, 2016	Dec. 31, 2016
2017 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	3	3
Derivative, Notional Amount	$ 45,000	$ 45,000
Derivative, Maturity Date	Dec. 31, 2017	Dec. 31, 2017
2018 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	11	9
Derivative, Notional Amount	$ 245,000	$ 205,000
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2018
2019 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	1
Derivative, Notional Amount	$ 20,000
Derivative, Maturity Date	Dec. 31, 2019

Derivatives And Risk Manageme53

Derivatives And Risk Management (Derivative Instruments Summary) (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross Asset	$ 82,353,000	$ 99,045,000
Gross Liability	(181,888,000)	(229,790,000)
Collateral Netting	38,762,000	44,390,000
Net Asset (Liability) in Balance Sheet	(60,773,000)	(86,355,000)
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Collateral Netting	16,362,000	15,510,000
Other Current Liabilities [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	4,000	1,000
Gross Liability	(74,000)	(21,000)
Collateral Netting	0	0
Net Asset (Liability) in Balance Sheet	(70,000)	(20,000)
Other Current Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	0	0
Gross Liability	(5,715,000)	(7,325,000)
Collateral Netting	0	0
Net Asset (Liability) in Balance Sheet	(5,715,000)	(7,325,000)
Other Current Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	1,781,000	966,000
Gross Liability	(325,000)	(506,000)
Collateral Netting	0	0
Net Asset (Liability) in Balance Sheet	1,456,000	460,000
Other Noncurrent Assets [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	250,000
Gross Liability	0
Collateral Netting	0
Net Asset (Liability) in Balance Sheet	250,000
Current Utility Energy Commodity Derivative Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	544,000	2,063,000
Gross Liability	(60,000)	(538,000)
Collateral Netting	0	0
Net Asset (Liability) in Balance Sheet	484,000	1,525,000
Current Utility Energy Commodity Derivative Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	51,995,000	66,421,000
Gross Liability	(73,946,000)	(97,586,000)
Collateral Netting	9,270,000	13,120,000
Net Asset (Liability) in Balance Sheet	(12,681,000)	(18,045,000)
Other Noncurrent Liabilities [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	7,589,000	0
Gross Liability	(53,364,000)	(69,737,000)
Collateral Netting	22,400,000	28,880,000
Net Asset (Liability) in Balance Sheet	(23,375,000)	(40,857,000)
Other Noncurrent Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Asset	20,190,000	29,594,000
Gross Liability	(48,404,000)	(54,077,000)
Collateral Netting	7,092,000	2,390,000
Net Asset (Liability) in Balance Sheet	$ (21,122,000)	$ (22,093,000)

Derivatives And Risk Manageme54

Derivatives And Risk Management Derivatives and Risk Management (Foreign Currency Exchange Contracts) (Details) CAD in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2015CADderivative_contracts	Jun. 30, 2015USD ($)derivative_contracts	Dec. 31, 2014CADderivative_contracts	Dec. 31, 2014USD ($)derivative_contracts
Foreign Currency Fair Value Hedge Derivative [Line Items]
Number Of Days Canadian Currency Prices Are Settled With U.S. Dollars	60 days
Number of Foreign Currency Derivatives Held | derivative_contracts	26	26	18	18
United States of America, Dollars | Foreign Exchange Contract [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative, Notional Amount		$ 8,183		$ 5,474
Canada, Dollars | Foreign Exchange Contract [Member]
Foreign Currency Fair Value Hedge Derivative [Line Items]
Derivative, Notional Amount | CAD	CAD 10,130		CAD 6,198

Derivatives And Risk Manageme55

Derivatives And Risk Management Derivatives and Risk Management (Collateral) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Liability position at aggregate fair value	$ 6,684	$ 12,911
Additional Collateral, Aggregate Fair Value	6,682	16,227
Derivative, Fair Value, Amount Offset Against Collateral, Net	38,762	44,390
Commodity Contracts [Member]
Derivative [Line Items]
Letters of credit outstanding	20,000	14,500
Derivative, Fair Value, Amount Offset Against Collateral, Net	16,362	15,510
Collateral Already Posted, Aggregate Fair Value	27,953	20,565
Interest Rate Swap [Member]
Derivative [Line Items]
Letters of credit outstanding	7,200	10,900
Derivative, Fair Value, Amount Offset Against Collateral, Net	22,400	28,880
Collateral Already Posted, Aggregate Fair Value	$ 22,400	$ 28,880

Asset Retirement Obligations 56

Asset Retirement Obligations Asset Retirement Obligations (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation	$ 14,791	$ 3,028
Asset Retirement Obligation, Liabilities Incurred	11,658
Asset Retirement Obligation, Liabilities Settled	(6)
Asset Retirement Obligation, Accretion Expense	$ 111

Pension Plans And Other Postr57

Pension Plans And Other Postretirement Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions	$ 8,000	$ 21,500	$ 32,000
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	$ (12,000)

Pension Plans And Other Postr58

Pension Plans And Other Postretirement Benefit Plans (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4,984	$ 3,868	$ 9,933	$ 8,886
Interest cost	6,531	6,706	13,203	13,412
Expected return on plan assets	(7,075)	(8,110)	(14,491)	(16,220)
Amortization of prior service cost	6	6	12	12
Net loss recognition	2,634	14	5,028	1,171
Net periodic benefit cost	7,080	2,484	13,685	7,261
Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	721	499	1,420	1,473
Interest cost	1,292	1,353	2,623	2,706
Expected return on plan assets	(500)	(472)	(931)	(944)
Amortization of prior service cost	(287)	(43)	(566)	(86)
Net loss recognition	1,263	349	2,555	1,175
Net periodic benefit cost	$ 2,489	$ 1,686	$ 5,101	$ 4,324

Committed Lines of Credit (Deta

Committed Lines of Credit (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jul. 01, 2014	Apr. 30, 2014
Short-term Debt [Line Items]
Line of Credit, Current	$ 90,000	$ 105,000
Avista Utilities [Member]
Short-term Debt [Line Items]
Line of Credit, Current	90,000	105,000
Letters of credit outstanding at end of period	$ 34,379	$ 32,579
Average interest rate at end of period	0.94%	0.93%
Alaska Electric Light & Power [Member]
Short-term Debt [Line Items]
Line of Credit, Current	$ 0	$ 0
Line of Credit [Member] | Avista Utilities [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 400,000
Line of Credit [Member] | Alaska Electric Light & Power [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 25,000

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Aug. 18, 1998
Debt Instrument [Line Items]
Capital Lease Obligations		$ 73,422		$ 73,422		$ 74,149
Long-term Pollution Control Bond, Noncurrent	[1]	$ (83,700)		$ (83,700)		$ (83,700)
Debt instrument, interest rate, stated percentage		1.16%		1.16%		1.11%
Utilities Operating Expense, Products and Services		$ 141,116	$ 128,922	$ 350,676	$ 349,419
2032 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Pollution Control Bond, Noncurrent		66,700		66,700
2034 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Pollution Control Bond, Noncurrent		17,000		17,000
AIDEA [Member]
Debt Instrument [Line Items]
Long Term Revenue Bonds							$ 100,000
Alaska Electric Light & Power [Member]
Debt Instrument [Line Items]
Capital Leased Assets, Gross		71,007		71,007		$ 71,007
Capital Leases Assets Accumulated Depreciation		3,641		3,641		$ 1,821
Alaska Electric Light & Power [Member] | Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Capital Lease Obligations		$ 68,840		68,840
Capital Lease Obligations Annual Minimum Payments of Principal and Interest				5,900
Power purchase agreement [Member] | Alaska Electric Light & Power [Member]
Debt Instrument [Line Items]
Utilities Operating Expense, Products and Services				$ 10,600
Minimum [Member] | AIDEA [Member] | Long-Term Revenue Bonds [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage							4.90%
Maximum [Member] | AIDEA [Member] | Long-Term Revenue Bonds [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage							6.00%
[1]	In December 2010, $66.7 million and $17.0 million of the City of Forsyth, Montana Pollution Control Revenue Refunding Bonds (Avista Corporation Colstrip Project) due in 2032 and 2034, respectively, which had been held by Avista Corp. since 2008 and 2009, respectively, were refunded by new bond issues (Series 2010A and Series 2010B). The new bonds were not offered to the public and were purchased by Avista Corp. due to market conditions. The Company expects that at a later date, subject to market conditions, these bonds may be remarketed to unaffiliated investors. So long as Avista Corp. is the holder of these bonds, the bonds will not be reflected as an asset or a liability on Avista Corp.'s Condensed Consolidated Balance Sheets.

Long-Term Debt (Schedule Of Lon

Long-Term Debt (Schedule Of Long-Term Debt Instruments) (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		1.16%	1.11%
Secured and Unsecured Debt		$ 1,526,700	$ 1,526,700
Interest Rate, minimum		1.11%	1.10%
Interest Rate, maximum		1.16%	1.11%
Secured Debt		$ 1,511,700	$ 1,511,700
Capital Lease Obligations		73,422	74,149
Settled interest rate swaps		(17,336)	(17,541)
Unamortized debt discount		(1,039)	(1,122)
Total		1,581,747	1,582,186
Pollution Control Bonds	[1]	(83,700)	(83,700)
Long-term Debt and Capital Lease Obligations, Current		(3,162)	(6,424)
Long-term debt and capital leases		$ 1,494,885	1,492,062
Document Period End Date		Jun. 30, 2015
2018, 7.39% - 7.45% [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Interest Rate, minimum		7.39%
Interest Rate, maximum		7.45%
2023, 7.18% - 7.54% [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Interest Rate, minimum		7.18%
Interest Rate, maximum		7.54%
2032 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Pollution Control Bonds		$ 66,700
2034 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Pollution Control Bonds		17,000
Avista Utilities [Member]
Debt Instrument [Line Items]
Secured Debt		$ 1,436,700	1,436,700
Avista Utilities [Member] | 2018, 5.95% [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,018
Debt instrument, interest rate, stated percentage		5.95%
Secured Debt		$ 250,000	250,000
Avista Utilities [Member] | 2018, 7.39% - 7.45% [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year		2,018
Medium-Term Notes, Noncurrent		$ 22,500	22,500
Avista Utilities [Member] | 2019 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,019
Debt instrument, interest rate, stated percentage		5.45%
Secured Debt		$ 90,000	90,000
Avista Utilities [Member] | 2020 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,020
Debt instrument, interest rate, stated percentage		3.89%
Secured Debt		$ 52,000	52,000
Avista Utilities [Member] | 2022 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,022
Debt instrument, interest rate, stated percentage		5.13%
Secured Debt		$ 250,000	250,000
Avista Utilities [Member] | 2023, 7.18% - 7.54% [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year		2,023
Medium-Term Notes, Noncurrent		$ 13,500	13,500
Avista Utilities [Member] | 2028 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year		2,028
Debt instrument, interest rate, stated percentage		6.37%
Medium-Term Notes, Noncurrent		$ 25,000	25,000
Avista Utilities [Member] | 2032 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year	[1]	2,032
Pollution Control Bonds	[1]	$ 66,700	66,700
Avista Utilities [Member] | 2034 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Maturity Year	[1]	2,034
Pollution Control Bonds	[1]	$ 17,000	17,000
Avista Utilities [Member] | 2035 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,035
Debt instrument, interest rate, stated percentage		6.25%
Secured Debt		$ 150,000	150,000
Avista Utilities [Member] | 2037 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,037
Debt instrument, interest rate, stated percentage		5.70%
Secured Debt		$ 150,000	150,000
Avista Utilities [Member] | 2040 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,040
Debt instrument, interest rate, stated percentage		5.55%
Secured Debt		$ 35,000	35,000
Avista Utilities [Member] | 2041 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,041
Debt instrument, interest rate, stated percentage		4.45%
Secured Debt		$ 85,000	85,000
Avista Utilities [Member] | 2047 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,047
Debt instrument, interest rate, stated percentage		4.23%
Secured Debt		$ 80,000	80,000
Avista Utilities [Member] | 2016 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,016
Debt instrument, interest rate, stated percentage		0.84%
Secured Debt		$ 90,000	90,000
Avista Utilities [Member] | 2044 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,044
Debt instrument, interest rate, stated percentage		4.11%
Secured Debt		$ 60,000	60,000
Alaska Electric Light & Power [Member] | 2044 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year		2,044
Debt instrument, interest rate, stated percentage		4.54%
Secured Debt	[2]	$ 75,000	75,000
Alaska Energy Resources Company [Member] | 2019 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Maturity Year		2,019
Debt instrument, interest rate, stated percentage		3.85%
Unsecured Debt		$ 15,000	$ 15,000
[1]	In December 2010, $66.7 million and $17.0 million of the City of Forsyth, Montana Pollution Control Revenue Refunding Bonds (Avista Corporation Colstrip Project) due in 2032 and 2034, respectively, which had been held by Avista Corp. since 2008 and 2009, respectively, were refunded by new bond issues (Series 2010A and Series 2010B). The new bonds were not offered to the public and were purchased by Avista Corp. due to market conditions. The Company expects that at a later date, subject to market conditions, these bonds may be remarketed to unaffiliated investors. So long as Avista Corp. is the holder of these bonds, the bonds will not be reflected as an asset or a liability on Avista Corp.'s Condensed Consolidated Balance Sheets.
[2]	Upon settlement of interest rate swaps, these are recorded as a regulatory asset or liability and included as part of long-term debt above. They are amortized as a component of interest expense over the life of the associated debt and included as a part of the Company's cost of debt calculation for ratemaking purposes.

Long-Term Debt (Schedule Of L62

Long-Term Debt (Schedule Of Long-Term Debt Maturities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Capital Lease Obligations	$ 73,422	$ 74,149

Long-Term Debt Long-Term Debt (

Long-Term Debt Long-Term Debt (Snettisham Capital Lease Obligation) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Capital Leased Assets [Line Items]
Capital Lease Obligations	$ 73,422		$ 73,422		$ 74,149
Alaska Electric Light & Power [Member]
Capital Leased Assets [Line Items]
Capital Leased Assets, Gross	71,007		71,007		71,007
Capital Leases Assets Accumulated Depreciation	3,641		3,641		1,821
Capital Leases, Income Statement, Interest Expense		$ 0		$ 0
Capital Leases, Income Statement, Amortization Expense		$ 0		$ 0
Alaska Electric Light & Power [Member] | Capital Lease Obligations [Member]
Capital Leased Assets [Line Items]
Capital Leases Future Minimum Payments of Principal Remainder Of Fiscal Year	1,115		1,115
Capital Lease Obligations	68,840		68,840
Capital Leases Future Minimum Payments of Principal Year Two	2,350		2,350
Capital Leases Future Minimum Payments of Principal Year Three	2,480		2,480
Capital Leases Future Minimum Payments of Principal Year Four	2,615		2,615
Capital Leases Future Minimum Payments of Principal Year Five	2,755		2,755
Capital Leases Future Minimum Payments of Principal Thereafter	57,525		57,525
Capital Leases Future Minimum Payments of Interest Remainder Of Fiscal Year	1,845		1,845
Capital Leases Future Minimum Payments of Interest Due in Two Years	3,567		3,567
Capital Leases Future Minimum Payments of Interest Due in Three Years	3,438		3,438
Capital Leases Future Minimum Payments of Interest Due in Four Years	3,305		3,305
Capital Leases Future Minimum Payments of Interest Due in Five Years	3,165		3,165
Capital Leases Future Minimum Payments of Interest Due Thereafter	25,364		25,364
Capital Leases Future Minimum Payments of Interest Due	40,684		40,684
Capital Leases, Future Minimum Payments, Remainder of Fiscal Year	2,960		2,960
Capital Leases, Future Minimum Payments Due in Two Years	5,917		5,917
Capital Leases, Future Minimum Payments Due in Three Years	5,918		5,918
Capital Leases, Future Minimum Payments Due in Four Years	5,920		5,920
Capital Leases, Future Minimum Payments Due in Five Years	5,920		5,920
Capital Leases, Future Minimum Payments Due Thereafter	82,889		82,889
Capital Leases, Future Minimum Payments Due	109,524		109,524
Alaska Electric Light & Power [Member] | Reported Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Capital Lease Obligations [Member]
Capital Leased Assets [Line Items]
Capital Lease Obligations	68,840		68,840		$ 69,955
Operating Expense [Member] | Alaska Electric Light & Power [Member]
Capital Leased Assets [Line Items]
Capital Leases, Income Statement, Interest Expense	922		1,845
Capital Leases, Income Statement, Amortization Expense	$ 910		$ 1,820

Long- Term Debt to Affiliated64

Long- Term Debt to Affiliated Trust Long-Term Debt to Affiliated Trust (Schedule of Distribution Rates Paid) (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Long-Term Debt to Affiliated Trust [Abstract]
Interest Rate, minimum	1.11%	1.10%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	1.16%	1.11%

Long- Term Debt to Affiliated65

Long- Term Debt to Affiliated Trust Long-Term Debt to Affiliated Trust (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2000	Dec. 31, 1997
Debt Instrument [Line Items]
Payments for Repurchase of Trust Preferred Securities		$ 10
Equity Method Investment, Ownership Percentage	100.00%
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	$ 51.5		$ 51.5
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Trust Preferred Securities			50
Debt Instrument, Description of Variable Rate Basis	LIBOR
Debt Instrument, Basis Spread on Variable Rate	0.875%
Common Trust Securities [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Trust Preferred Securities			$ 1.5

Fair Value (Carrying Value And

Fair Value (Carrying Value And Estimated Fair Value Of Financial Instruments) (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Capital Lease Obligations	$ 73,422	$ 74,149
Reported Value Measurement [Member] | Level 2 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	951,000	951,000
Reported Value Measurement [Member] | Level 3 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	492,000	492,000
Reported Value Measurement [Member] | Level 3 [Member] | Nonrecourse Long-Term Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	$ 0	1,431
Estimate of Fair Value Measurement [Member] | Secured and Unsecured Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Fair Value Inputs, Offered Quotes	$ 100
Estimate of Fair Value Measurement [Member] | Level 2 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	$ 1,087,197	1,118,972
Estimate of Fair Value Measurement [Member] | Level 3 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	496,848	527,663
Estimate of Fair Value Measurement [Member] | Level 3 [Member] | Nonrecourse Long-Term Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	$ 0	1,440
Minimum [Member] | Estimate of Fair Value Measurement [Member] | Secured and Unsecured Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Fair Value Inputs, Offered Quotes	$ 73
Maximum [Member] | Estimate of Fair Value Measurement [Member] | Secured and Unsecured Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Fair Value Inputs, Offered Quotes	$ 123.32
Alaska Electric Light & Power [Member] | Capital Lease Obligations [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Capital Lease Obligations	$ 68,840
Alaska Electric Light & Power [Member] | Reported Value Measurement [Member] | Level 3 [Member] | Capital Lease Obligations [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Capital Lease Obligations	68,840	69,955
Alaska Electric Light & Power [Member] | Estimate of Fair Value Measurement [Member] | Level 3 [Member] | Capital Lease Obligations [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Capital Lease Obligations	75,174	79,290
Affiliated Entity [Member] | Reported Value Measurement [Member] | Level 3 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	51,547	51,547
Affiliated Entity [Member] | Estimate of Fair Value Measurement [Member] | Level 3 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	$ 37,629	$ 38,582

Fair Value (Fair Value Of Asset

Fair Value (Fair Value Of Assets And Liabilities Measured On Recurring Basis) (Details) - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset		$ 82,353	$ 99,045
Liability		181,888	229,790
Cash and cash equivalents		16,242	22,143	$ 207,967	$ 82,574
Fixed Income Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents		700	800
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and collateral netting, assets	[1]	(80,163)	(97,060)
Interest rate swaps		1,706	460
Funds held in trust account of Spokane Energy			1,600
Total		10,219	11,452
Counterparty and collateral netting, liabilities	[1]	(118,925)	(141,450)
Interest rate swaps		29,090	48,182
Total		62,963	88,340
Fair Value, Measurements, Recurring [Member] | Natural Gas Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and collateral netting, assets	[1]	(1)	(1,349)
Derivative Asset		0	0
Counterparty and collateral netting, liabilities	[1]	(1)	(1,349)
Derivative Liability		6,825	35
Fair Value, Measurements, Recurring [Member] | Power Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and collateral netting, liabilities	[1]	0	0
Derivative Liability		18,616	23,299
Fair Value, Measurements, Recurring [Member] | Interest Rate Swap [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and collateral netting, assets	[1]	(7,914)	(506)
Counterparty and collateral netting, liabilities	[1]	(30,314)	(29,386)
Fair Value, Measurements, Recurring [Member] | Energy commodity derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and collateral netting, assets	[1]	(72,244)	(95,204)
Derivative Asset		484	1,525
Counterparty and collateral netting, liabilities	[1]	(88,606)	(110,714)
Derivative Liability		8,217	16,380
Fair Value, Measurements, Recurring [Member] | Power Option Agreement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and collateral netting, liabilities	[1]	0	0
Derivative Liability		145	424
Fair Value, Measurements, Recurring [Member] | Foreign Exchange Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Counterparty and collateral netting, assets	[1]	(4)	(1)
Derivative Asset		0	0
Counterparty and collateral netting, liabilities	[1]	(4)	(1)
Derivative Liability		70	20
Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	[2]	1,830	1,793
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	[2]	6,199	6,074
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Funds held in trust account of Spokane Energy			1,600
Total		8,029	9,467
Total		0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Fixed Income Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	[2]	1,830	1,793
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	[2]	6,199	6,074
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps		9,620	966
Total		82,352	97,696
Interest rate swaps		59,404	77,568
Total		156,301	204,683
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Energy commodity derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset		72,728	96,729
Liability		96,823	127,094
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Foreign Exchange Contract [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset		4	1
Liability		74	21
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total		1	1,349
Total		25,587	25,107
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Natural Gas Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset		1	1,349
Liability		6,826	1,384
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Power Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability		18,616	23,299
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Power Option Agreement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability		$ 145	$ 424
[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 trading securities and are included in other property and investments-net on the Condensed Consolidated Balance Sheets.

Fair Value (Quantitative Inform

Fair Value (Quantitative Information) (Details) $ / shares in Units, $ in Thousands		6 Months Ended
		Jun. 30, 2015USD ($)$ / MWHMMBTUMWh$ / shares$ / MmBtu	Dec. 31, 2014USD ($)
Power Exchange Agreements [Member] | 2014 to 2019 [Member] | Surrogate Facility Pricing [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Escalation Factor		3.00%
Power Option Agreement [Member] | Black Scholes Merton [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Assumptions, Expected Volatility Rate	[1]	20.00%
Power Option Agreement [Member] | 2015 [Member] | Black Scholes Merton [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Assumptions, Expected Volatility Rate	[1]	39.00%
Fair Value Assumptions, Exercise Price | $ / shares		$ 43.44
Power Option Agreement [Member] | 2019 [Member] | Black Scholes Merton [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Assumptions, Exercise Price | $ / shares		$ 55.66
Power Option Agreement [Member] | 2018 [Member] | Black Scholes Merton [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Assumptions, Expected Volatility Rate	[1]	20.00%
Minimum [Member] | Power Exchange Agreements [Member] | Surrogate Facility Pricing [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Operation and Maintenance Charges	[2]	30.66
Transaction/Delivery Volumes | MWh		392,608
Minimum [Member] | Power Option Agreement [Member] | Black Scholes Merton [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Transaction/Delivery Volumes | MWh		285,979
Maximum [Member] | Power Exchange Agreements [Member] | Surrogate Facility Pricing [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Operation and Maintenance Charges	[2]	55.56
Transaction/Delivery Volumes | MWh		397,030
Maximum [Member] | Power Option Agreement [Member] | Black Scholes Merton [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Transaction/Delivery Volumes | MWh		287,147
Average [Member] | Power Exchange Agreements [Member] | Surrogate Facility Pricing [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Operation and Maintenance Charges	[2]	42.90
Fair Value, Measurements, Recurring [Member] | Power Exchange Agreements [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative Liability | $		$ (18,616)	$ (23,299)
Fair Value, Measurements, Recurring [Member] | Power Option Agreement [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative Liability | $		(145)	(424)
Fair Value, Measurements, Recurring [Member] | Natural Gas Exchange Agreements [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative Liability | $		$ (6,825)	$ (35)
WASHINGTON | Average [Member] | Power Exchange Agreements [Member] | Surrogate Facility Pricing [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Operation and Maintenance Charges		43.11
IDAHO | Average [Member] | Power Exchange Agreements [Member] | Surrogate Facility Pricing [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Operation and Maintenance Charges		42.90
Sales [Member] | Minimum [Member] | Natural Gas Exchange Agreements [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Forward Price | $ / MmBtu		2.47
Transaction/Delivery Volumes | MMBTU		60,000
Sales [Member] | Maximum [Member] | Natural Gas Exchange Agreements [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Forward Price | $ / MmBtu		4.08
Transaction/Delivery Volumes | MMBTU		310,000
Purchase [Member] | Minimum [Member] | Natural Gas Exchange Agreements [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Forward Price | $ / MmBtu		2.27
Transaction/Delivery Volumes | MMBTU		125,000
Purchase [Member] | Maximum [Member] | Natural Gas Exchange Agreements [Member] | Internally Derived Weighted Average Cost Of Gas [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Forward Price | $ / MmBtu		3.19
Transaction/Delivery Volumes | MMBTU		310,000
[1]	The estimated volatility rate of 0.20 is compared to actual quoted volatility rates of 0.39 for 2015 to 0.20 in July 2018.
[2]	The average O&M charges for the delivery year beginning in November 2014 were $42.90 per MWh. For ratemaking purposes the average O&M charges to be included for recovery in retail rates vary slightly between regulatory jurisdictions. The average O&M charges for the delivery year beginning in 2014 were $43.11 for Washington and $42.90 for Idaho.

Fair Value (Reconciliation For

Fair Value (Reconciliation For All Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Unobservable Inputs (Level 3)) (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		$ (25,337)	$ (16,470)	$ (23,758)	$ (16,435)
Included in net income		0	0	0	0
Included in other comprehensive income		0	0	0	0
Included in regulatory assets/liabilities	[1]	(1,506)	5,087	(6,937)	9,309
Purchases		0	0	0	0
Issuances		0	0	0	0
Settlements		1,257	676	5,109	(3,581)
Transfers from other categories		0	0	0	0
Ending Balance		(25,586)	(10,707)	(25,586)	(10,707)
Natural Gas Exchange Agreements [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value						$ 817
Natural Gas Exchange Agreements [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance			(2,418)	(35)	(1,219)
Included in net income		0	0	0	0
Included in other comprehensive income		0	0	0	0
Included in regulatory assets/liabilities	[1]	(8,163)	235	(7,386)	2,084
Purchases		0	0	0	0
Issuances		0	0	0	0
Settlements		521	0	596	(3,048)
Transfers from other categories		0	0	0	0
Ending Balance		(6,825)	(2,183)	(6,825)	(2,183)
Power Option Agreement [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		(251)	(428)	(424)	(775)
Included in net income		0	0	0	0
Included in other comprehensive income		0	0	0	0
Included in regulatory assets/liabilities	[1]	106	(177)	279	170
Purchases		0	0	0	0
Issuances		0	0	0	0
Settlements		0	0	0	0
Transfers from other categories		0	0	0	0
Ending Balance		(145)	(605)	(145)	(605)
Power Exchange Agreements [Member]
Fair Value Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		(25,903)	(13,624)	(23,299)	(14,441)
Included in net income		0	0	0	0
Included in other comprehensive income		0	0	0	0
Included in regulatory assets/liabilities	[1]	6,551	5,029	170	7,055
Purchases		0	0	0	0
Issuances		0	0	0	0
Settlements		736	676	4,513	(533)
Transfers from other categories		0	0	0	0
Ending Balance		$ (18,616)	$ (7,919)	$ (18,616)	$ (7,919)
[1]	Natural Gas Exchange Agreement Power Exchange Agreement Power Option Agreement TotalThree months ended June 30, 2015: Balance as of April 1, 2015$817 $(25,903) $(251) $(25,337)Total gains or losses (realized/unrealized): Included in net income— — — —Included in other comprehensive income— — — —Included in regulatory assets/liabilities(8,163) 6,551 106 (1,506)Purchases— — — —Issuance— — — —Settlements521 736 — 1,257Transfers to/from other categories— — — —Ending balance as of June 30, 2015$(6,825) $(18,616) $(145) $(25,586)Three months ended June 30, 2014: Balance as of April 1, 2014$(2,418) $(13,624) $(428) $(16,470)Total gains or losses (realized/unrealized): Included in net income— — — —Included in other comprehensive income— — — —Included in regulatory assets/liabilities235 5,029 (177) 5,087Purchases— — — —Issuance— — — —Settlements— 676 — 676Transfers to/from other categories— — — —Ending balance as of June 30, 2014$(2,183) $(7,919) $(605) $(10,707)Six months ended June 30, 2015: Balance as of January 1, 2015$(35) $(23,299) $(424) $(23,758)Total gains or losses (realized/unrealized): Included in net income— — — —Included in other comprehensive income— — — —Included in regulatory assets/liabilities(7,386) 170 279 (6,937)Purchases— — — —Issuance— — — —Settlements596 4,513 — 5,109Transfers to/from other categories— — — —Ending balance as of June 30, 2015$(6,825) $(18,616) $(145) $(25,586) Natural Gas Exchange Agreement Power Exchange Agreement Power Option Agreement TotalSix months ended June 30, 2014: Balance as of January 1, 2014$(1,219) $(14,441) $(775) $(16,435)Total gains or losses (realized/unrealized): Included in net income— — — —Included in other comprehensive income— — — —Included in regulatory assets/liabilities2,084 7,055 170 9,309Purchases— — — —Issuance— — — —Settlements(3,048) (533) — (3,581)Transfers from other categories— — — —Ending balance as of June 30, 2014$(2,183) $(7,919) $(605) $(10,707)

Earnings Per Share Attributable

Earnings Per Share Attributable To Avista Corporation (Computation Of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations Attributable to Parent	$ 25,050	$ 31,254	$ 71,499	$ 78,730
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	196	69,617	196	70,640
Numerator:
Net income attributable to Avista Corporation shareholders	25,246	100,871	71,695	149,370
Subsidiary earnings adjustment for dilutive securities	0	58	0	5
Adjusted net income attributable to Avista Corporation shareholders for computation of diluted earnings per common share	$ 196	$ 69,675	$ 196	$ 70,645
Denominator:
Weighted-average number of common shares outstanding-basic	62,281	60,184	62,299	60,153
Performance and restricted stock awards	319	279	445	163
Weighted-average number of common shares outstanding-diluted	62,600	60,463	62,744	60,316
Earnings per common share attributable to Avista Corporation:
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.41	$ 0.52	$ 1.15	$ 1.31
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0	1.16	0	1.17
Basic	0.41	1.68	1.15	2.48
Income (Loss) from Continuing Operations, Per Diluted Share	0.40	0.52	1.14	1.31
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0	1.15	0	1.17
Diluted (usd per share)	$ 0.40	$ 1.67	$ 1.14	$ 2.48

Commitments And Contingencies (

Commitments And Contingencies (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)employeegal	Oct. 31, 2014USD ($)
Loss Contingencies [Line Items]
Number Of Bargaining Unit Employees Oregon | employee	50
Gallons of Diesel Spilled | gal	10,000
Public Utilities Property Plant And Equipment Proposed Amount Of Disallowed Costs For Recently Completed Plant	$ 12.7
Avista Utilities [Member]
Loss Contingencies [Line Items]
Percentage Of Employees, Collective Bargaining Agreement	45.00%
Majority Of Bargaining Unit Employees, Percentage	90.00%
Alaska Electric Light & Power [Member]
Loss Contingencies [Line Items]
Percentage Of Employees, Collective Bargaining Agreement	54.00%
Investment One [Member]
Loss Contingencies [Line Items]
Other Commitment	$ 2.3	$ 3.1

Information By Business Segme72

Information By Business Segments (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Operating revenues		$ 337,332		$ 312,580		$ 783,822	$ 759,158
Resource costs		141,116		128,922		350,676	349,419
Other operating expenses		79,758		68,229		162,746	144,949
Depreciation and amortization		35,841		31,331		70,310	62,204
Income from operations		57,360		62,731		146,935	153,073
Interest expense	[1]	19,981		18,659		39,995	37,514
Income taxes		15,016		16,691		41,263	43,973
Income (Loss) from Continuing Operations Attributable to Parent		25,050		31,254		71,499	78,730
Payments to Acquire Other Property, Plant, and Equipment		96,247	[2]	76,845	[2]	178,256	136,616
Total assets		4,679,989				4,679,989		$ 4,712,331
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	[3]	(100)		(450)		(550)	(900)
Resource costs	[3]	0		0		0	0
Other operating expenses	[3]	(100)		(450)		(550)	(900)
Depreciation and amortization	[3]	0		0		0	0
Income from operations	[3]	0		0		0	0
Interest expense	[1],[3]	(30)		(79)		(52)	(167)
Income taxes	[3]	0		0		0	0
Income (Loss) from Continuing Operations Attributable to Parent	[3]	0		79		0	167
Payments to Acquire Other Property, Plant, and Equipment	[3]	0		0		0	0
Total assets	[3]	0				0		0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues		330,930		303,555		767,787	741,129
Resource costs		141,116		128,922		350,676	349,419
Other operating expenses		73,112		67,349		146,284	134,686
Depreciation and amortization		35,676		31,180		69,976	61,906
Income from operations		57,769		54,737		147,696	145,605
Interest expense	[1]	19,864		18,422		39,736	36,968
Income taxes		15,223		13,302		41,795	40,922
Income (Loss) from Continuing Operations Attributable to Parent		25,403		26,685		72,421	74,681
Payments to Acquire Other Property, Plant, and Equipment	[2]	96,155		76,789		177,752	136,514
Total assets		4,630,157				4,630,157		4,632,121
Operating Segments [Member] | Avista Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues		320,698		303,555		744,781	741,129
Resource costs		137,896		128,922		344,556	349,419
Other operating expenses		70,348		67,349		140,757	134,686
Depreciation and amortization		34,351		31,180		67,348	61,906
Income from operations		55,415		54,737		140,203	145,605
Interest expense	[1]	18,969		18,422		37,937	36,968
Income taxes		14,632		13,302		39,520	40,922
Income (Loss) from Continuing Operations Attributable to Parent		24,478		26,685		68,862	74,681
Payments to Acquire Other Property, Plant, and Equipment		90,800		76,789		172,012	136,514
Total assets		4,361,550				4,361,550		4,367,926
Operating Segments [Member] | Alaska Electric Light & Power [Member]
Segment Reporting Information [Line Items]
Operating revenues		10,232		0		23,006	0
Resource costs		3,220		0		6,120	0
Other operating expenses		2,764		0		5,527	0
Depreciation and amortization		1,325		0		2,628	0
Income from operations		2,354		0		7,493	0
Interest expense	[1]	895		0		1,799	0
Income taxes		591		0		2,275	0
Income (Loss) from Continuing Operations Attributable to Parent		925		0		3,559	0
Payments to Acquire Other Property, Plant, and Equipment		5,355		0		5,740	0
Total assets		268,607				268,607		264,195
Operating Segments [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating revenues		6,502		9,475		16,585	18,929
Resource costs		0		0		0	0
Other operating expenses		6,746		1,330		17,012	11,163
Depreciation and amortization		165		151		334	298
Income from operations		(409)		7,994		(761)	7,468
Interest expense	[1]	147		316		311	713
Income taxes		(207)		3,389		(532)	3,051
Income (Loss) from Continuing Operations Attributable to Parent		(353)		4,490		(922)	3,882
Payments to Acquire Other Property, Plant, and Equipment		92	[2]	$ 56	[2]	504	$ 102
Total assets		$ 49,832				$ 49,832		$ 80,210
[1]	Including interest expense to affiliated trusts.
[2]	The capital expenditures for the other businesses are included as other capital expenditures on the Condensed Consolidated Statements of Cash Flows. The remainder of the balance included in other capital expenditures on the Condensed Consolidated Statements of Cash Flows in 2014 are related to Ecova.
[3]	Intersegment eliminations reported as operating revenues and resource costs represent intercompany purchases and sales of electric capacity and energy. Intersegment eliminations reported as interest expense and net income (loss) attributable to Avista Corp. shareholders represent intercompany interest.