Long-Term Debt and Capital Leases Long-Term Debt and Capital Leases (Schedule of Capital Lease Obligation Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Capital Lease Obligations Principal	$ 57,210	$ 62,148
Alaska Electric Light & Power [Member] | Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Capital Lease Obligations Principal Year 1	2,660
Capital Leases Obligations Principal Year 2	2,800
Capital Leases Obligations Principal Year 3	2,935
Capital Leases Obligations Principal Year 4	3,085
Capital Leases Obligations Principal Year 5	3,235
Capital Leases Obligations Principal Thereafter	42,495
Capital Lease Obligations Principal	57,210
Capital Lease Obligations Interest Year 1	2,795
Capital Leases Obligations Interest Year 2	2,662
Capital Leases Obligations Interest Year 3	2,522
Capital Leases Obligations Interest Year 4	2,375
Capital Leases Obligations Interest Year 5	2,221
Capital Leases Obligations Interest Thereafter	12,079
Capital Leases Obligations Interest	24,654
Capital Leases, Future Minimum Payments, Year 1	5,455
Capital Leases, Future Minimum Payments Year 2	5,462
Capital Leases, Future Minimum Payments Year 3	5,457
Capital Leases, Future Minimum Payments Year 4	5,460
Capital Leases, Future Minimum Payments Year 5	5,456
Capital Leases, Future Minimum Payments Thereafter	54,574
Capital Leases, Future Minimum Payments Due	$ 81,864