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Long-Term Debt - Schedule Of Long-Term Debt Instruments (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 | Dec. 31, 2022
Debt Instrument [Line Items] |  |
Secured Debt | $ 2,618,700 | $ 2,382,200
Secured and Unsecured Debt | 2,633,700 | 2,397,200
Unamortized debt discount | (689) | (726)
Unamortized Debt Issuance Expense | (18,953) | (18,261)
Total | 2,614,058 | 2,378,213
Current portion of long-term debt | (15,000) | (13,500)
Non Affiliated Trusts [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt | $ 2,515,358 | 2,281,013
First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Interest Rate, Stated Percentage | 8.00% |
Secured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Pollution Control Bonds | $ (83,700) | (83,700)
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 | $ 2,543,700 | 2,307,200
Avista Utilities [Member] | 2023 7.18% - 7.54% [Member] | Secured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2023 |
Medium-Term Notes, Noncurrent | $ 0 | 13,500
Avista Utilities [Member] | 2023 7.18% - 7.54% [Member] | Minimum [Member] | Secured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Interest Rate, Stated Percentage | 7.18% |
Avista Utilities [Member] | 2023 7.18% - 7.54% [Member] | Maximum [Member] | Secured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Debt Instrument, Interest Rate, Stated Percentage | 7.54% |
Avista Utilities [Member] | 2028 [Member] | Secured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2028 |
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 | 2032 |
Pollution Control Bonds | $ 66,700 | 66,700
Avista Utilities [Member] | 2034 [Member] | Secured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2034 |
Pollution Control Bonds | $ 17,000 | 17,000
Avista Utilities [Member] | 2035 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2035 |
Debt Instrument, Interest Rate, Stated Percentage | 6.25% |
Secured Debt | $ 150,000 | 150,000
Avista Utilities [Member] | 2037 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2037 |
Debt Instrument, Interest Rate, Stated Percentage | 5.70% |
Secured Debt | $ 150,000 | 150,000
Avista Utilities [Member] | 2040 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2040 |
Debt Instrument, Interest Rate, Stated Percentage | 5.55% |
Secured Debt | $ 35,000 | 35,000
Avista Utilities [Member] | 2041 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2041 |
Debt Instrument, Interest Rate, Stated Percentage | 4.45% |
Secured Debt | $ 85,000 | 85,000
Avista Utilities [Member] | 2044 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2044 |
Debt Instrument, Interest Rate, Stated Percentage | 4.11% |
Secured Debt | $ 60,000 | 60,000
Avista Utilities [Member] | 2045 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2045 |
Debt Instrument, Interest Rate, Stated Percentage | 4.37% |
Secured Debt | $ 100,000 | 100,000
Avista Utilities [Member] | 2047 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2047 |
Debt Instrument, Interest Rate, Stated Percentage | 4.23% |
Secured Debt | $ 80,000 | 80,000
Avista Utilities [Member] | 2047 3.91% [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2047 |
Debt Instrument, Interest Rate, Stated Percentage | 3.91% |
Secured Debt | $ 90,000 | 90,000
Avista Utilities [Member] | 2048 4.35% [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2048 |
Debt Instrument, Interest Rate, Stated Percentage | 4.35% |
Secured Debt | $ 375,000 | 375,000
Avista Utilities [Member] | 2049 3.43% [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2049 |
Debt Instrument, Interest Rate, Stated Percentage | 3.43% |
Secured Debt | $ 180,000 | 180,000
Avista Utilities [Member] | 2050 3.07% [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2050 |
Debt Instrument, Interest Rate, Stated Percentage | 3.07% |
Secured Debt | $ 165,000 | 165,000
Avista Utilities [Member] | 2051 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2051 |
Debt Instrument, Interest Rate, Stated Percentage | 3.54% |
Secured Debt | $ 175,000 | 175,000
Avista Utilities [Member] | 2.90% Due in 2051 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2051 |
Debt Instrument, Interest Rate, Stated Percentage | 2.90% |
Secured Debt | $ 140,000 | 140,000
Avista Utilities [Member] | 2052 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2052 |
Debt Instrument, Interest Rate, Stated Percentage | 4.00% |
Secured Debt | $ 400,000 | 400,000
Avista Utilities [Member] | 2053 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2053 |
Debt Instrument, Interest Rate, Stated Percentage | 5.66% |
Secured Debt | $ 250,000 |
Alaska Electric Light & Power [Member] | 2044 [Member] | First Mortgage [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2044 |
Debt Instrument, Interest Rate, Stated Percentage | 4.54% |
Secured Debt | $ 75,000 | 75,000
Alaska Energy Resources Company [Member] | 2024 [Member] | Unsecured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Maturity Year | 2024 |
Debt Instrument, Interest Rate, Stated Percentage | 3.44% |
Unsecured Debt | $ 15,000 | $ 15,000

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