CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Accounts receivable and unbilled revenues, reserves	$ 155.0	$ 193.5
Property, plant, and equipment, accumulated depreciation and amortization	$ 11,442.8	$ 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	316,354,446	315,434,531
Regulatory assets (September 30, 2024 and December 31, 2023 include $79.1 and $85.9, respectively, related to WEPCo Environmental Trust)	$ 3,346.5	$ 3,249.8
Current portion of long-term debt (September 30, 2024 and December 31, 2023 include $9.1 and $9.0, respectively, related to WEPCo Environmental Trust)	1,823.7	1,264.2
WEPCo Environmental Trust
Regulatory assets (September 30, 2024 and December 31, 2023 include $79.1 and $85.9, respectively, related to WEPCo Environmental Trust)	79.1	85.9
Current portion of long-term debt (September 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 (September 30, 2024 and December 31, 2023 include $80.9 and $85.3, respectively, related to WEPCo Environmental Trust)	$ 80.9	$ 85.3

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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