Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2020

Long Term Debt [Abstract]

Schedule of Long-term Debt Instruments

Maturity Year	Description	Interest Rate	2020			2019
Avista Corp. Secured Long-Term Debt
2020	First Mortgage Bonds	3.89%		—			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	4.37%		100,000			100,000
2047	First Mortgage Bonds	4.23%		80,000			80,000
2047	First Mortgage Bonds	3.91%		90,000			90,000
2048	First Mortgage Bonds	4.35%		375,000			375,000
2049	First Mortgage Bonds	3.43%		180,000			180,000
2050	First Mortgage Bonds (2)	3.07%		165,000			—
2051	First Mortgage Bonds	3.54%		175,000			175,000
	Total Avista Corp. secured long-term debt			2,017,200			1,904,200
Alaska Electric Light and Power Company Secured Long-Term Debt
2044	First Mortgage Bonds	4.54%		75,000			75,000
	Total secured long-term debt			2,092,200			1,979,200
Alaska Energy and Resources Company Unsecured Long-Term Debt
2024	Unsecured Term Loan	3.44%		15,000			15,000
	Total secured and unsecured long-term debt			2,107,200			1,994,200
Other Long-Term Debt Components
	Unamortized debt discount			(710	)		(788	)
	Unamortized long-term debt issuance costs			(14,256	)		(13,944	)
	Total			2,092,234			1,979,468
	Secured Pollution Control Bonds held by Avista    Corporation (1)			(83,700	)		(83,700	)
	Current portion of long-term debt			—			(52,000	)
	Total long-term debt		$	2,008,534		$	1,843,768

(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 variable rate 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 September 2020, the Company issued and sold $165.0 million of 3.07 percent first mortgage bonds due in 2050 pursuant to a bond purchase agreement with institutional investors in the private placement market. The total net proceeds from the sale of the bonds were used to repay maturing long-term debt of $52.0 million and repay a portion of the outstanding balance under Avista Corp.'s $400.0 million committed line of credit. In connection with the pricing of the first mortgage bonds in June 2020, the Company cash settled seven interest rate swap derivatives (notional aggregate amount of $70.0 million) and paid a net amount of $33.5 million. See Note 7 for a discussion of interest rate swap derivatives.

Schedule of Maturities of Long-term Debt

	2021		2022		2023		2024		2025		Thereafter		Total
Debt maturities	$	—	$	250,000	$	13,500	$	15,000	$	—	$	1,796,547	$	2,075,047