CONDENSED INCOME STATEMENTS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Operating revenues	$ 491.5	$ 478.9
Operating expenses
Cost of sales	227.4	227.5
Other operation and maintenance	107.9	83.7
Depreciation and amortization	55.0	49.7
Property and revenue taxes	12.2	10.9
Total operating expenses	402.5	371.8
Operating income	89.0	107.1
Other income, net	11.7	10.1
Interest expense	21.8	16.6
Other expense	(10.1)	(6.5)
Income before income taxes	78.9	100.6
Income tax expense	12.6	24.0
Net income	$ 66.3	$ 76.6