Fair Value (Carrying Value And Estimated Fair Value Of Financial Instruments) (Details) $ in Thousands	Dec. 31, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($)
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Finance Lease, Liability	$ 54,550
Capital Lease Obligations	0	$ 57,210
Estimated Fair Value [Member] \| Level 2 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	1,124,649	1,142,292
Estimated Fair Value [Member] \| Level 3 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	1,048,440	734,742
Estimated Fair Value [Member] \| Level 3 [Member] \| Affiliated Entity [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	41,238	38,145
Carrying Value [Member] \| Level 2 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	963,500	1,053,500
Carrying Value [Member] \| Level 3 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	947,000	767,000
Carrying Value [Member] \| Level 3 [Member] \| Affiliated Entity [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Long-term debt	51,547	51,547
Alaska Electric Light & Power [Member] \| Estimated Fair Value [Member] \| Level 3 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Finance Lease, Liability	58,000
Capital Lease Obligations		55,600
Alaska Electric Light & Power [Member] \| Carrying Value [Member] \| Level 3 [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Finance Lease, Liability	$ 54,550
Capital Lease Obligations		$ 57,210
Measurement Input, Quoted Price [Member] \| Estimated Fair Value [Member] \| Secured and Unsecured Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Fair Value Measurement Inputs, Offered Quotes \| $ / shares	100.00
Measurement Input, Quoted Price [Member] \| Minimum [Member] \| Estimated Fair Value [Member] \| Secured and Unsecured Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Fair Value Measurement Inputs, Offered Quotes \| $ / shares	80.00
Measurement Input, Quoted Price [Member] \| Maximum [Member] \| Estimated Fair Value [Member] \| Secured and Unsecured Debt [Member]
Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]
Fair Value Measurement Inputs, Offered Quotes \| $ / shares	134.11

Fair Value and Carrying Value, by Balance Sheet Grouping [Line Items]

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- Definition

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

+ References

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-Publisher FASB
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- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

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Value of input used to measure long-term debt.

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