Consolidated Income Statements - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Operating revenues	$ 8,599.9	$ 8,893.0	$ 9,597.4
Operating expenses
Cost of sales	2,656.0	3,191.2	4,358.9
Other operation and maintenance	2,158.0	2,100.5	1,938.0
Impairment related to ICC disallowances	12.1	178.9	0.0
Depreciation and amortization	1,354.5	1,264.2	1,122.6
Property and revenue taxes	266.5	250.2	253.7
Total operating expenses	6,447.1	6,985.0	7,673.2
Operating income	2,152.8	1,908.0	1,924.2
Equity in earnings of transmission affiliates	207.5	177.5	194.7
Other income, net	178.2	177.7	128.8
Interest expense	815.3	727.4	515.1
Gain on debt extinguishments	(23.1)	(0.5)	0.0
Other expense	(406.5)	(371.7)	(191.6)
Income before income taxes	1,746.3	1,536.3	1,732.6
Income tax expense	222.0	204.6	322.9
Net income	1,524.3	1,331.7	1,409.7
Preferred stock dividends of subsidiary	1.2	1.2	1.2
Net (income) loss attributed to noncontrolling interests	4.1	1.2	(0.4)
Net income attributed to common shareholders	$ 1,527.2	$ 1,331.7	$ 1,408.1
Earnings per share
Basic (in dollars per share)	$ 4.83	$ 4.22	$ 4.46
Diluted (in dollars per share)	$ 4.83	$ 4.22	$ 4.45
Weighted average common shares outstanding
Basic (in shares)	316.2	315.4	315.4
Diluted (in shares)	316.5	315.9	316.1