Regulatory Assets and Liabilities - Regulatory Assets (Details-1) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Regulatory Asset [Line Items]
Regulatory Asset	$ 113,441	$ 109,012
Asset Retirement Obligation [Member]
Regulatory Asset [Line Items]
Regulatory Asset	14,721	13,081
Deferred Fuel Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	12,067	3,292
Deferred Bad Debt Expense [Member]
Regulatory Asset [Line Items]
Regulatory Asset	7,650	5,600
Debt Related Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	7,580	8,173
Deferred Pension And Other Postretirement Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	0	1,017
Derivatives [Member]
Regulatory Asset [Line Items]
Regulatory Asset	5,094	0
Leases [Member]
Regulatory Asset [Line Items]
Regulatory Asset	3,656	2,992
Tax Recovery Related to AFUDC Equity [Member]
Regulatory Asset [Line Items]
Regulatory Asset	10,851	10,347
Unfunded Pension and Other Postretirement Plans Costs [Member]
Regulatory Asset [Line Items]
Regulatory Asset	50,072	63,728
Other Regulatory Asset [Member]
Regulatory Asset [Line Items]
Regulatory Asset	$ 1,750	$ 782