Revenue Revenue Utility Related Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule Of Utilities Operating Revenue Expense Taxes [Line Items]
Public Utility Operating Expenses Excise Taxes Collected	$ 19,167	$ 21,584
Alaska Electric Light & Power [Member]
Schedule Of Utilities Operating Revenue Expense Taxes [Line Items]
Public Utility Operating Expenses Excise Taxes Collected			$ 2,000