Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 85,411	$ 75,464
Accounts and notes receivable-less allowances of $44,341 and $44,155, respectively	147,851	193,683
Utility energy commodity derivative assets	2,250	4,139
Regulatory asset for utility derivatives	27,876	35,082
Investments and funds held for clients	92,345	88,272
Materials and supplies, fuel stock and natural gas stored	45,322	47,455
Deferred income taxes	32,860	34,281
Income taxes receivable	131	2,777
Other current assets	34,647	24,641
Total current assets	468,693	505,794
Net Utility Property:
Utility plant in service	4,185,614	4,054,644
Construction work in progress	133,166	143,098
Total	4,318,780	4,197,742
Less: Accumulated depreciation and amortization	1,214,604	1,174,026
Total net utility property	3,104,176	3,023,716
Other Non-current Assets:
Investment in exchange power-net	15,108	16,333
Investment in affiliated trusts	11,547	11,547
Goodwill	76,762	75,959
Intangible assets-net of accumulated amortization of $31,260 and $26,030, respectively	42,457	46,256
Long-term energy contract receivable of Spokane Energy	46,446	52,033
Other property and investments-net	64,021	46,542
Total other non-current assets	256,341	248,670
Deferred Charges:
Regulatory assets for deferred income tax	70,192	79,406
Regulatory assets for pensions and other postretirement benefits	297,042	306,408
Other regulatory assets	105,737	103,946
Non-current utility energy commodity derivative assets	135	1,093
Non-current regulatory asset for utility derivatives	31,588	25,218
Other deferred charges	13,892	18,928
Total deferred charges	518,586	534,999
Total assets	4,347,796	4,313,179
Current Liabilities:
Accounts payable	153,425	198,914
Client fund obligations	94,059	87,839
Current portion of long-term debt	50,320	50,372
Current portion of nonrecourse long-term debt of Spokane Energy	15,662	14,965
Short-term borrowings	95,500	52,000
Utility energy commodity derivative liabilities	22,373	29,515
Other current liabilities	151,122	142,544
Total current liabilities	582,461	576,149
Long-term debt	1,181,925	1,178,367
Nonrecourse long-term debt of Spokane Energy	9,812	17,838
Long-term debt to affiliated trusts	51,547	51,547
Long-term borrowings under committed line of credit	52,000	54,000
Regulatory liability for utility plant retirement costs	244,225	234,128
Pensions and other postretirement benefits	263,270	283,985
Deferred income taxes	517,830	524,877
Other non-current liabilities and deferred credits	122,488	110,215
Total liabilities	3,025,558	3,031,106
Commitments and Contingencies (See Notes to Consolidated Financial Statements)
Redeemable Noncontrolling Interests	7,817	4,938
Avista Corporation Stockholders’ Equity:
Common stock, no par value; 200,000,000 shares authorized; 59,980,023 and 59,812,796 shares outstanding, respectively	895,255	889,237
Accumulated other comprehensive loss	(7,636)	(6,700)
Retained earnings	406,195	376,940
Total Avista Corporation stockholders’ equity	1,293,814	1,259,477
Noncontrolling Interests	20,607	17,658
Total equity	1,314,421	1,277,135
Total liabilities and equity	$ 4,347,796	$ 4,313,179