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)

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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