Business Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Income Tax Expense (Benefit)	$ 8,314	$ 3,802	$ 24,833	$ 8,663
Net Income (Loss) Attributable to Parent	54,068	35,431	89,725	62,552
UTILITY OPERATING REVENUES	449,171	402,887	1,254,566	1,290,580
Depreciation and amortization	85,493	72,021	248,846	212,292
Interest Expense	44,198	34,471	131,681	104,510
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	62,382	39,233	114,558	71,215
Assets	7,032,943	6,181,523	7,032,943	6,181,523	$ 6,181,523
Electric [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	85,493	72,021	248,846	212,292
Interest Expense	33,745	23,502	99,007	71,604
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	73,109	49,887	146,058	104,005
Assets	6,998,420	6,129,581	6,998,420	6,129,581
Other Segments [Member]
Segment Reporting Information [Line Items]
UTILITY OPERATING REVENUES	0	0	0	0
Depreciation and amortization	0	0	0	0
Interest Expense	10,453	10,969	32,674	32,906
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(10,727)	(10,654)	(31,500)	(32,790)
Assets	34,523	51,942	34,523	51,942
Electricity [Member]
Segment Reporting Information [Line Items]
UTILITY OPERATING REVENUES	$ 449,171	$ 402,887	$ 1,254,566	$ 1,290,580