CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Operating Revenues	$ 452,756	$ 435,853
Operating Expenses
Fuel	101,454	124,070
Purchased Power	26,230	36,440
Transmission and Other PPFAC Recoverable Costs	18,078	16,599
Increase (Decrease) to Reflect PPFAC Recovery Treatment	32,768	7,914
Total Fuel and Purchased Power	178,530	185,023
Operations and Maintenance	118,749	108,059
Depreciation	55,604	47,140
Amortization	7,736	9,691
Taxes Other Than Income Taxes	18,752	17,277
Total Operating Expenses	379,371	367,190
Operating Income	73,385	68,663
Other Income (Expense)
Interest Expense	(24,005)	(23,316)
Allowance For Borrowed Funds	1,876	1,008
Allowance For Equity Funds	5,252	2,893
Unrealized Gains (Losses) on Investments	862	1,360
Other, Net	1,296	2,091
Total Other Income (Expense)	(14,720)	(15,964)
Income Before Income Tax Expense	58,665	52,699
Income Tax Expense	7,484	5,806
Net Income	$ 51,181	$ 46,893