Unaudited Condensed Consolidated Statements Of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Costs and Expenses	$ 282,708	$ 253,797	$ 572,011	$ 536,407
REVENUES	330,587	311,503	692,788	668,885
Cost of Revenue [Abstract]
Fuel Costs	52,840	43,351	137,571	112,139
Cost of Goods and Services Sold	41,748	43,082	66,331	78,549
OPERATING EXPENSES:
Utilities Operating Expense, Maintenance and Operations	116,381	94,659	220,330	200,248
Depreciation and amortization	62,994	61,099	126,083	121,807
Taxes other than income taxes	8,745	11,606	21,696	23,664
Operating Income (Loss)	47,879	57,706	120,777	132,478
Allowance for equity funds used during construction	1,331	1,160	2,705	2,017
Interest Expense	32,199	33,935	62,266	64,016
Other Nonoperating Income (Expense)	4,704	1,772	9,318	1,979
Nonoperating Income (Expense)	(26,164)	(33,418)	(50,243)	(62,435)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	21,715	24,288	70,534	70,043
Income Tax Expense (Benefit)	4,505	5,165	14,540	14,937
Net income	17,210	19,123	55,994	55,106
Less: Dividends on preferred stock	804	804	1,607	1,607
Net Income (Loss) Available to Common Stockholders, Basic	16,406	18,319	54,387	53,499
Gain (Loss) on Extinguishment of Debt	0	(2,415)	0	(2,415)
OPERATING INCOME	47,879	57,706	120,777	132,478
OTHER INCOME / (EXPENSE), NET:
Allowance for equity funds used during construction	1,331	1,160	2,705	2,017
Interest Expense	(32,199)	(33,935)	(62,266)	(64,016)
Other Nonoperating Income (Expense)	4,704	1,772	9,318	1,979
Total other expense, net	(26,164)	(33,418)	(50,243)	(62,435)
EARNINGS FROM OPERATIONS BEFORE INCOME TAX
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	21,715	24,288	70,534	70,043
Income Tax Expense (Benefit)	4,505	5,165	14,540	14,937
NET INCOME	17,210	19,123	55,994	55,106
Less: Dividends on preferred stock	804	804	1,607	1,607
NET INCOME APPLICABLE TO COMMON STOCK	16,406	18,319	54,387	53,499
Electricity [Member]
REVENUES	$ 330,587	$ 311,503	$ 692,788	$ 668,885