CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Income Statement [Abstract]
OPERATING REVENUES (Note 4)	$ 1,358,751	$ 1,308,994	$ 2,391,031	$ 2,260,706
OPERATING EXPENSES
Fuel and purchased power	477,008	437,172	857,079	795,036
Operations and maintenance	286,605	272,266	586,714	529,844
Depreciation and amortization	228,893	225,017	463,833	435,311
Taxes other than income taxes	57,651	58,651	117,005	117,815
Other expense	1,042	2,141	1,626	2,161
Total	1,051,199	995,247	2,026,257	1,880,167
OPERATING INCOME	307,552	313,747	364,774	380,539
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	14,767	8,910	28,016	19,202
Pension and other postretirement non-service credits, net (Note 7)	3,692	12,877	6,650	24,445
Other income (Note 11)	12,104	5,885	29,565	36,492
Other expense (Note 11)	(4,259)	(3,032)	(6,829)	(10,599)
Total	26,304	24,640	57,402	69,540
INTEREST EXPENSE
Interest charges	113,527	108,891	218,470	208,665
Allowance for borrowed funds used during construction	(11,559)	(11,036)	(21,661)	(24,177)
Total	101,968	97,855	196,809	184,488
Income Before Income Taxes	231,888	240,532	225,367	265,591
Income taxes	35,018	32,421	28,835	36,312
Net Income	196,870	208,111	196,532	229,279
Less: Net income attributable to noncontrolling interests (Note 8)	4,306	4,306	8,612	8,612
Net Income Attributable to Common Shareholders	$ 192,564	$ 203,805	$ 187,920	$ 220,667
Weighted-average common shares outstanding - basic (in shares)	119,517	113,695	119,555	113,658
Weighted-average common shares outstanding - diluted (in shares)	121,865	115,803	121,813	115,015
Earnings Per Weighted-Average Common Share Outstanding
Net income attributable to common shareholders — basic (in dollars per share)	$ 1.61	$ 1.79	$ 1.57	$ 1.94
Net income attributable to common shareholders — diluted (in dollars per share)	$ 1.58	$ 1.76	$ 1.54	$ 1.92