Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities:
Net Margin including Non-controlling interest	$ 12,843	$ 11,770	$ 20,025
Adjustments to reconcile net margin to net cash provided by operating activities:
Depreciation and amortization	69,573	69,167	70,416
Other non-cash charges	17,173	16,192	16,886
Change in current assets	(924)	(119,343)	14,170
Change in deferred energy	114,538	(78,831)	(28,117)
Change in current liabilities	(164,849)	80,459	56,303
Change in regulatory assets and liabilities	(106,202)	(19,453)	72,527
Change in deferred charges and other assets and deferred credits and other liabilities	41,580	(19,567)	(24,619)
Net Cash (Used for) Provided by Operating Activities	(16,268)	(59,606)	197,591
Investing Activities:
Purchases of held to maturity securities		(80,012)
Proceeds from sale of held to maturity securities		80,600
Purchases of available for sale securities			(15,000)
Proceeds from sale of available for sale securities			15,000
Increase in other investments	(5,925)	(3,491)	(20,105)
Electric plant additions	(52,943)	(31,089)	(29,881)
Net Cash Used for Investing Activities	(58,868)	(33,992)	(49,986)
Financing Activities:
Debt issuance costs	(752)
Payments of long-term debt	(49,041)	(49,041)	(49,041)
Draws on revolving credit facility	528,000	152,500
Repayments on revolving credit facility	(387,000)	(102,500)
Net Cash Provided by (Used for) Financing Activities	91,207	959	(49,041)
Net Change in Cash and Cash Equivalents	16,071	(92,639)	98,564
Cash and Cash Equivalents - Beginning of Period	15,213	107,852	9,288
Cash and Cash Equivalents - End of Period	$ 31,284	$ 15,213	$ 107,852