Common Equity - Schedule of Earnings Per Share Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Net income	$ 50.2	$ 62.7
Basic average common shares outstanding	206.3	201.2
Contingently issuable shares (performance and restricted stock units)	0.5	0.7
Forward equity sale agreements	0.4	0.0
Diluted average common shares outstanding	207.2	201.9
Basic earnings per average common share	$ 0.24	$ 0.31
Diluted earnings per average common share	$ 0.24	$ 0.31
Anti-dilutive shares excluded from earnings per share calculation	0.0	0.0
Retained Earnings [Member]
Net income	$ 50.2	$ 62.7