Commitments And Contingencies (Narrative) (Details)	6 Months Ended
	Jun. 30, 2018 USD ($) agreement Mcf	Dec. 31, 2017 USD ($)
Other Commitments [Line Items]
Contingency accruals	$ 0
Patronage capital payable, noncurrent	8,798,077	$ 8,798,077
Matanuska Electric Association, Inc. [Member]
Other Commitments [Line Items]
Patronage capital payable, noncurrent	4,900,000	4,900,000
Homer Electric Association, Inc. [Member]
Other Commitments [Line Items]
Patronage capital payable, noncurrent	$ 5,900,000	$ 5,900,000
Hilcorp Alaska - Cook Inlet [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
Estimated amount of gas under contract | Mcf	60,000,000
Percentage Of Met Natural Gas Needs	100.00%
Number of contract extensions | agreement	2
International Brotherhood of Electrical Workers [Member]
Other Commitments [Line Items]
Percentage of employees belonging to unions	70.00%
Number of collective bargaining agreements | agreement	3
Expiration date of collective bargaining agreements	Jun. 30, 2021