Regulatory Assets and Liabilities - Regulatory Assets (Details-1) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Regulatory Asset [Line Items]
Regulatory Asset	$ 45,286	$ 102,568
Asset Retirement Obligation [Member]
Regulatory Asset [Line Items]
Regulatory Asset	6,813	17,003
Deferred Bad Debt Expense [Member]
Regulatory Asset [Line Items]
Regulatory Asset	5,200	9,150
Debt Related Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	6,538	7,014
Derivatives [Member]
Regulatory Asset [Line Items]
Regulatory Asset	0	5,226
Deferred Fuel Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	0	6,713
Leases [Member]
Regulatory Asset [Line Items]
Regulatory Asset	4,598	4,130
Deferred Pension And Other Postretirement Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	642	4,948
Tax Recovery Related to AFUDC Equity [Member]
Regulatory Asset [Line Items]
Regulatory Asset	13,440	12,140
Electric Transmission Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	1,216	1,998
Unfunded Pension and Other Postretirement Plans Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	0	31,374
Other Regulatory Asset [Member]
Regulatory Asset [Line Items]
Regulatory Asset	$ 6,839	$ 2,872