Regulatory Assets and Liabilities - Regulatory Assets (Details-1) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Regulatory Assets [Line Items]
Regulatory Assets	$ 109,012	$ 157,252
Asset Retirement Obligation [Member]
Regulatory Assets [Line Items]
Regulatory Assets	13,081	11,935
Deferred Fuel Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	3,292	0
Deferred Bad Debt Expense [Member]
Regulatory Assets [Line Items]
Regulatory Assets	5,600	3,750
Debt Related Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	8,173	8,586
Deferred Pension And Other Postretirement Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	1,017	5,280
Derivatives [Member]
Regulatory Assets [Line Items]
Regulatory Assets	0	13,989
Leases [Member]
Regulatory Assets [Line Items]
Regulatory Assets	2,992	2,748
Tax Recovery AFUDC Equity [Member]
Regulatory Assets [Line Items]
Regulatory Assets	10,347	8,952
Unfunded Pension and Other Postretirement Plans Costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets	63,728	101,594
Other Regulatory Asset [Member]
Regulatory Assets [Line Items]
Regulatory Assets	$ 782	$ 418