CONDENSED INCOME STATEMENTS - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Income Statement [Abstract]
Revenues	$ 410.5	$ 337.0	$ 909.2	$ 764.2
Operating expenses
Cost of sales	123.5	89.7	313.7	244.6
Other operation and maintenance	121.8	111.3	241.1	215.9
Depreciation and amortization	66.7	59.2	132.5	118.3
Property and revenue taxes	11.0	11.5	22.4	23.5
Total operating expenses	323.0	271.7	709.7	602.3
Operating income	87.5	65.3	199.5	161.9
Other income, net	4.2	12.5	8.5	24.0
Interest expense	24.2	23.9	48.2	47.9
Other expense	(20.0)	(11.4)	(39.7)	(23.9)
Income before income taxes	67.5	53.9	159.8	138.0
Income tax expense	12.3	10.2	28.8	26.9
Net income	$ 55.2	$ 43.7	$ 131.0	$ 111.1