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Summary Of Significant Accounting Policies (Goodwill) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018
Goodwill [Line Items] |  |
Goodwill | $ 52,426 | $ 57,672
Goodwill, Written off Related to Sale of Business Unit | (5,246) |
Accumulated Impairment Losses [Member] |  |
Goodwill [Line Items] |  |
Goodwill, Written off Related to Sale of Business Unit | 7,733 |
Goodwill, Impaired, Accumulated Impairment Loss | 0 | (7,733)
Alaska Electric Light & Power [Member] |  |
Goodwill [Line Items] |  |
Goodwill | 52,426 | 52,426
Goodwill, Written off Related to Sale of Business Unit | 0 |
Corporate and Other [Member] |  |
Goodwill [Line Items] |  |
Goodwill | 0 | $ 12,979
Goodwill, Written off Related to Sale of Business Unit | $ (12,979) |

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