Long-Term Debt (Schedule Of Long-Term Debt Instruments) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended						9 Months Ended						9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended				9 Months Ended				9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended				1 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013		Dec. 31, 1998	Sep. 30, 2014 2018, 7.39% - 7.45% [Member] Secured Debt [Member]	Sep. 30, 2014 2023, 7.18% - 7.54% [Member] Secured Debt [Member]	Sep. 30, 2014 2032 [Member] Secured Debt [Member]	Sep. 30, 2014 2034 [Member] Secured Debt [Member]	Sep. 30, 2014 Avista Corporation [Member]	Dec. 31, 2013 Avista Corporation [Member]	Sep. 30, 2014 Avista Corporation [Member] 2018, 5.95% [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2018, 5.95% [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2018, 7.39% - 7.45% [Member] Secured Debt [Member]	Dec. 31, 2013 Avista Corporation [Member] 2018, 7.39% - 7.45% [Member] Secured Debt [Member]	Sep. 30, 2014 Avista Corporation [Member] 2019 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2019 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2020 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2020 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2022 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2022 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2023, 7.18% - 7.54% [Member] Secured Debt [Member]	Dec. 31, 2013 Avista Corporation [Member] 2023, 7.18% - 7.54% [Member] Secured Debt [Member]	Sep. 30, 2014 Avista Corporation [Member] 2028 [Member] Secured Debt [Member]	Dec. 31, 2013 Avista Corporation [Member] 2028 [Member] Secured Debt [Member]	Sep. 30, 2014 Avista Corporation [Member] 2032 [Member] Secured Debt [Member]		Dec. 31, 2013 Avista Corporation [Member] 2032 [Member] Secured Debt [Member]		Sep. 30, 2014 Avista Corporation [Member] 2034 [Member] Secured Debt [Member]		Dec. 31, 2013 Avista Corporation [Member] 2034 [Member] Secured Debt [Member]		Sep. 30, 2014 Avista Corporation [Member] 2035 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2035 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2037 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2037 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2040 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2040 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2041 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2041 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2047 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2047 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Avista Corporation [Member] 2016 [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 Avista Corporation [Member] 2016 [Member] First Mortgage Bonds [Member]	Sep. 30, 2014 Alaska Electric Light & Power [Member] 2044 [Member] First Mortgage Bonds [Member]		Dec. 31, 2013 Alaska Electric Light & Power [Member] 2044 [Member] First Mortgage Bonds [Member]		Oct. 31, 2014 Subsequent Event [Member]	Oct. 31, 2014 Subsequent Event [Member] Avista Corporation [Member] 2044 [Member] First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Maturity Year													2018		2018		2019		2020		2022		2023		2028		2032	[1]			2034	[1]			2035		2037		2040		2041		2047		2016		2044
Debt instrument, interest rate, stated percentage						8.45%							5.95%				5.45%		3.89%		5.13%				6.37%										6.25%		5.70%		5.55%		4.45%		4.23%		0.84%		4.54%					4.11%
Interest Rate, minimum							7.39%	7.18%
Interest Rate, maximum							7.45%	7.54%
Medium-Term Notes, Noncurrent															$ 22,500	$ 22,500							$ 13,500	$ 13,500	$ 25,000	$ 25,000
Secured Debt	1,451,700			1,376,700							1,376,700	1,376,700	250,000	250,000			90,000	90,000	52,000	52,000	250,000	250,000													150,000	150,000	150,000	150,000	35,000	35,000	85,000	85,000	80,000	80,000	90,000	90,000	75,000	[2]	0	[2]		60,000
Other long-term debt and capital leases	1,412,211			1,272,425
Settled interest rate swaps	(23,118)	[3]		(23,560)	[3]
Unamortized debt discount	(954)			(1,287)
Total	1,502,382			1,356,483
Pollution Control Bonds	(83,700)	[1]		(83,700)	[1]				66,700	17,000																	66,700	[1]	66,700	[1]	17,000	[1]	17,000	[1]
Other Long-term Debt and Capital Lease Obligations	74,754			4,630
Long-term Debt and Capital Lease Obligations, Current	(6,471)			(358)
Payments for (Proceeds from) Derivative Instrument, Financing Activities	$ 0		$ 2,901																																																$ 5,400
Document Period End Date	Sep. 30, 2014

[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] In September 2014, AEL&P issued $75.0 million of 4.54 percent first mortgage bonds due in 2044 to two institutional investors in the private placement market. The first mortgage bonds were issued under and in accordance with the AEL&P Mortgage and Deed of Trust, dated as of July 1, 2014.

[3] 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.