Commitments And Contingencies (Narrative) (Details) MMcf in Thousands, Mcf in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($) Mcf MMcf	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) $ / kWh contract item Mcf MMcf	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Feb. 04, 2016
Other Commitments [Line Items]
Contingency accruals	$ 0								$ 0
Operating revenues	57,741,954	$ 45,132,973	$ 44,622,517	$ 50,250,135	$ 50,640,703	$ 43,109,512	$ 47,697,820	$ 74,973,117	$ 197,747,579	$ 216,421,152	$ 281,318,513
Percentage of power generated from gas									77.00%	86.00%
Patronage capital payable	12,008,499				11,108,071				$ 12,008,499	$ 11,108,071
Regulatory initial cost charge per KWH | $ / kWh									0.000626
Regulatory current cost charge per KWH | $ / kWh									0.000675
Percentage of three year average of gross retail revenue to be spent on underground lines									2.00%
Average of gross revenue to determine expenditure for underground lines									3 years
Percentage of retail bill collected to move existing overhead lines underground									2.00%
Other current liabilities	3,234,586				8,076,903				$ 3,234,586	$ 8,076,903
Beluga Power Plant [Member]
Other Commitments [Line Items]
Percentage of power generated from gas									9.00%	30.00%
Southcentral Power Project Plant [Member]
Other Commitments [Line Items]
Percentage of power generated from gas									88.00%	61.00%
Matanuska Electric Association, Inc. [Member]
Other Commitments [Line Items]
Patronage capital payable	4,100,000				3,200,000				$ 4,100,000	$ 3,200,000
Homer Electric Association, Inc. [Member]
Other Commitments [Line Items]
Power contracts expiration date									Dec. 31, 2013
Patronage capital payable	$ 7,900,000				7,900,000				$ 7,900,000	7,900,000
ConocoPhillips (COP) [Member]
Other Commitments [Line Items]
Commencement date of long term contract for purchase of gas supply									Aug. 21, 2009
Expiration date of long term contract for purchase of gas supply									Dec. 31, 2016
Estimated amount of gas under contract | MMcf	62								62
Percentage of met natural gas needs									70.00%
Hilcorp Alaska, LLC [Member]
Other Commitments [Line Items]
Commencement date of long term contract for purchase of gas supply									Jan. 01, 2015
Expiration date of long term contract for purchase of gas supply									Mar. 31, 2018
Hilcorp Alaska, LLC, Purchase Commitment Amendment 1 [Member]
Other Commitments [Line Items]
Commencement date of long term contract for purchase of gas supply									Sep. 15, 2014
Expiration date of long term contract for purchase of gas supply									Mar. 31, 2019
Percentage of met natural gas needs									100.00%
Hilcorp Alaska, LLC, Purchase Commitment Amendment 2 [Member]
Other Commitments [Line Items]
Commencement date of long term contract for purchase of gas supply									Sep. 08, 2015
Expiration date of long term contract for purchase of gas supply									Mar. 31, 2023
Estimated amount of gas under contract | Mcf	60.0								60.0
Percentage of met natural gas needs									100.00%
Marathon Alaska Production, LLC [Member]
Other Commitments [Line Items]
Commencement date of long term contract for purchase of gas supply									Apr. 01, 2011
Expiration date of long term contract for purchase of gas supply									Mar. 31, 2023
Estimated amount of gas under contract | MMcf	49								49
Number of contract extensions | contract									2
Percentage of met natural gas needs									100.00%
Moving Overhead Lines Underground [Member]
Other Commitments [Line Items]
Other current liabilities	$ 2,507,482				$ 5,184,551				$ 2,507,482	$ 5,184,551
Beluga River Unit [Member]
Other Commitments [Line Items]
Operating revenues									$ 2,800,000
Estimated amount of gas under contract | Mcf	25.1								25.1
Working interest ownership percentage	10.00%								10.00%			30.00%
Beluga River Unit [Member] | Municipal Light & Power [Member]
Other Commitments [Line Items]
Working interest ownership percentage	56.70%								56.70%			70.00%
International Brotherhood of Electrical Workers [Member]
Other Commitments [Line Items]
Percentage of employees belonging to unions	70.00%								70.00%
Number of collective bargaining agreements | item									3
Expiration date of collective bargaining agreements									Jun. 30, 2021
Hotel Employees and Restaurant Employees [Member]
Other Commitments [Line Items]
Number of collective bargaining agreements | item									1
Expiration date of collective bargaining agreements									Jun. 30, 2021