Long-Term Debt and Capital Leases (Tables)

12 Months Ended

Dec. 31, 2015

Debt Instrument [Line Items]

Long-term Debt Outstanding

Maturity Year	Description	Interest 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
2045	First Mortgage Bonds (2)	4.37%	100,000			—
2047	First Mortgage Bonds	4.23%	80,000			80,000
	Total Avista Corp. secured long-term debt		1,536,700			1,436,700
AEL&P Secured Long-Term Debt
2044	First Mortgage Bonds	4.54%	75,000			75,000
	Total secured long-term debt		1,611,700			1,511,700
AERC Unsecured Long-Term Debt
2019	Unsecured Term Loan	3.85%	15,000			15,000
	Total secured and unsecured long-term debt		1,626,700			1,526,700
Other Long-Term Debt Components
	Capital lease obligations		68,601			74,149
	Settled interest rate swaps (3)		(26,515		)	(17,541		)
	Unamortized debt discount		(956		)	(1,122		)
	Unamortized long-term debt issuance costs		(10,852		)	(11,360		)
	Total		1,656,978			1,570,826
	Secured Pollution Control Bonds held by Avista Corporation (1)		(83,700		)	(83,700		)
	Current portion of long-term debt and capital leases		(93,167		)	(6,424		)
	Total long-term debt and capital leases		$	1,480,111		$	1,480,702

(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 Consolidated Balance Sheets.

(2) In December 2015, Avista Corp. issued $100.0 million of first mortgage bonds to five institutional investors in a private placement transaction. The first mortgage bonds bear an interest rate of 4.37 percent and mature in 2045. The total net proceeds from the sale of the new bonds were used to repay a portion of the borrowings outstanding under the Company’s $400.0 million committed line of credit and for general corporate purposes.

(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.

Long-term Debt Maturities

	2016		2017		2018		2019		2020		Thereafter		Total
Debt maturities	$	90,000	$	—	$	272,500	$	105,000	$	52,000	$	1,075,047	$	1,594,547

Capital Lease Obligations [Member]

Debt Instrument [Line Items]

Long-term Debt Maturities

	2016		2017		2018		2019		2020		Thereafter		Total
Principal	$	2,295	$	2,415	$	2,535	$	2,660	$	2,800	$	51,750	$	64,455
Interest	3,157		3,042		2,921		2,795		2,662		19,195		33,772
Total	$	5,452	$	5,457	$	5,456	$	5,455	$	5,462	$	70,945	$	98,227