Other Income, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Other Income and Expenses [Abstract]
Non-service components of net periodic benefit costs	Other income, net	Other income, net	Other income, net
Non-service components of net periodic benefit costs	$ 83.7	$ 97.7	$ 104.4
AFUDC - Equity	59.8	59.1	29.4
Interest income	17.2	3.9	1.2
Gains (losses) from investments held in rabbi trust	11.7	13.7	(12.6)
Other, net	1.1	4.4	(2.9)
Other income, net	178.2	177.7	128.8
Equity method investments excluding transmission affiliates
Earnings (loss) from equity method investment	$ 4.7	$ (1.1)	$ 9.3