Business Segment Information (Reconciliation of Operating Profit (Loss) from Segments to Consolidated) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Revenues	$ 2,846,874	$ 2,794,628
Utilities Operating Expense, Fuel Used	344,522	616,617
Utilities Operating Expense, Purchased Power	345,746	228,142
Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses	672,667	687,031
Other Regulatory Charges Credits Net	(16,843)	109,346
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	362,422	76,536
Preferred dividend requirements of subsidiaries and net income (loss) attributable to noncontrolling interests	1,662	1,255
Net Income (Loss) Available to Common Stockholders, Basic	360,760	75,281
Operating Segments [Member] | Utility [Member]
Revenues	2,829,597	2,772,173
Utilities Operating Expense, Fuel Used	338,983	604,404
Utilities Operating Expense, Purchased Power	342,084	219,194
Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses	662,474	680,715
Other Regulatory Charges Credits Net	(16,843)	109,346
Segment Reporting, Other Segment Item, Amount	1,011,857	962,534
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	491,042	195,980
Operating Segments [Member] | Corporate Segment and Other Operating Segment [Member]
Revenues	17,303	22,476
Consolidation, Eliminations
Revenues	(26)	(21)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(75,248)	(79,561)
Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment | Corporate Segment and Other Operating Segment [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (53,372)	$ (39,883)