CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 26.0	$ 24.8
Accounts receivable and unbilled revenues, net of reserves of $199.7 and $220.1, respectively	1,103.8	1,202.8
Materials, supplies, and inventories	645.7	528.6
Prepayments	195.7	263.4
Amounts recoverable from customers	139.4	20.0
Derivative assets	247.1	17.0
Other	51.2	26.4
Current assets	2,408.9	2,083.0
Long-term assets
Property, plant, and equipment, net of accumulated depreciation and amortization of $9,799.3 and $9,364.7, respectively	26,622.7	25,707.4
Regulatory assets (September 30, 2021 includes $102.9 related to WEPCo Environmental Trust)	3,488.7	3,524.1
Equity investment in transmission affiliates	1,791.3	1,764.3
Goodwill	3,052.8	3,052.8
Other	1,036.5	896.5
Long-term assets	35,992.0	34,945.1
Total assets	38,400.9	37,028.1
Current liabilities
Short-term debt	1,508.9	1,776.9
Current portion of long-term debt (September 30, 2021 includes $8.5 related to WEPCo Environmental Trust)	496.7	785.8
Accounts payable	872.8	880.7
Other	814.2	704.7
Current liabilities	3,692.6	4,148.1
Long-term liabilities
Long-term debt (September 30, 2021 includes $107.0 related to WEPCo Environmental Trust)	12,678.1	11,728.1
Deferred income taxes	4,295.8	4,059.8
Deferred revenue, net	394.9	412.2
Regulatory liabilities	4,131.2	3,928.1
Environmental remediation liabilities	510.3	532.9
Pension and OPEB obligations	307.8	327.0
Other	1,283.6	1,229.4
Long-term liabilities	23,601.7	22,217.5
Commitments and contingencies (Note 20)
Common shareholders' equity
Common stock – $0.01 par value; 325,000,000 shares authorized; 315,434,531 shares outstanding	3.2	3.2
Additional paid in capital	4,144.4	4,143.7
Retained earnings	6,764.5	6,329.6
Accumulated other comprehensive loss	(3.6)	(6.8)
Common shareholders' equity	10,908.5	10,469.7
Preferred stock of subsidiary	30.4	30.4
Noncontrolling interests	167.7	162.4
Total liabilities and equity	$ 38,400.9	$ 37,028.1