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Revenue Revenue Utility Related Taxes (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | Dec. 31, 2017
Schedule Of Utilities Operating Revenue Expense Taxes [Line Items] |  |  |  |  |
Public Utility Operating Expenses Excise Taxes Collected | $ 12,986 | $ 13,552 | $ 32,153 | $ 35,136 |
Alaska Electric Light & Power [Member] |  |  |  |  |
Schedule Of Utilities Operating Revenue Expense Taxes [Line Items] |  |  |  |  |
Public Utility Operating Expenses Excise Taxes Collected |  |  |  |  | $ 2,000

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