CONDENSED CONSOLIDATED INCOME STATEMENTS - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Operating revenues	$ 2,908.1	$ 2,691.4
Operating expenses
Cost of sales	1,383.4	1,265.6
Other operation and maintenance	454.4	479.9
Depreciation and amortization	278.1	261.4
Property and revenue taxes	60.8	55.2
Total operating expenses	2,176.7	2,062.1
Operating income	731.4	629.3
Equity in earnings of transmission affiliates	41.7	42.6
Other income, net	39.6	32.8
Interest expense	117.6	119.5
Other expense	(36.3)	(44.1)
Income before income taxes	695.1	585.2
Income tax expense	127.1	74.9
Net income	568.0	510.3
Preferred stock dividends of subsidiary	0.3	0.3
Net (income) loss attributable to noncontrolling interests	1.8	(0.1)
Net income attributed to common shareholders	$ 565.9	$ 510.1
Earnings per share
Basic (in dollars per share)	$ 1.79	$ 1.62
Diluted (in dollars per share)	$ 1.79	$ 1.61
Weighted average common shares outstanding
Basic (in shares)	315.4	315.4
Diluted (in shares)	316.2	316.2