CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Accounts receivable and unbilled revenues, reserves	$ 166.9	$ 193.5
Property, plant, and equipment, accumulated depreciation and amortization	$ 11,263.4	$ 11,073.1
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	650,000,000	650,000,000
Common stock, shares outstanding	316,079,401	315,434,531
Regulatory assets (June 30, 2024 and December 31, 2023 include $82.3 and $85.9, respectively, related to WEPCo Environmental Trust)	$ 3,393.1	$ 3,249.8
Current portion of long-term debt (June 30, 2024 and December 31, 2023 include $9.1 and $9.0, respectively, related to WEPCo Environmental Trust)	1,157.4	1,264.2
WEPCo Environmental Trust
Regulatory assets (June 30, 2024 and December 31, 2023 include $82.3 and $85.9, respectively, related to WEPCo Environmental Trust)	82.3	85.9
Current portion of long-term debt (June 30, 2024 and December 31, 2023 include $9.1 and $9.0, respectively, related to WEPCo Environmental Trust)	9.1	9.0
Long-term debt (June 30, 2024 and December 31, 2023 include $80.9 and $85.3, respectively, related to WEPCo Environmental Trust)	$ 80.9	$ 85.3