CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Statement of Financial Position [Abstract]
Accounts receivable and unbilled revenues, reserves	$ 148.9	$ 148.7
Property, plant, and equipment, accumulated depreciation and amortization	$ 12,783.3	$ 12,411.5
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	325,849,383	325,461,519
Regulatory assets (June 30, 2026 and December 31, 2025 include $63.6 and $67.5, respectively, related to WEPCo Environmental Trust)	$ 3,130.4	$ 3,156.3
Current portion of long-term debt (June 30, 2026 and December 31, 2025 include $9.4 and $9.3, respectively, related to WEPCo Environmental Trust)	1,413.5	1,519.4
Long-term debt (June 30, 2026 and December 31, 2025 include $62.8 and $67.4, respectively, related to WEPCo Environmental Trust)	19,216.3	18,498.1
WEPCo Environmental Trust
Regulatory assets (June 30, 2026 and December 31, 2025 include $63.6 and $67.5, respectively, related to WEPCo Environmental Trust)	63.6	67.5
Current portion of long-term debt (June 30, 2026 and December 31, 2025 include $9.4 and $9.3, respectively, related to WEPCo Environmental Trust)	9.4	9.3
Long-term debt (June 30, 2026 and December 31, 2025 include $62.8 and $67.4, respectively, related to WEPCo Environmental Trust)	$ 62.8	$ 67.4

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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