CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 48.1	$ 38.9
Accounts receivable and unbilled revenues, net of reserves of $160.5 and $143.2, respectively	1,356.8	1,350.7
Materials, supplies, and inventories	376.0	539.0
Prepayments	165.9	210.0
Other	34.0	74.9
Current assets	1,980.8	2,213.5
Long-term assets
Property, plant, and equipment, net of accumulated depreciation of $8,819.8 and $8,618.5, respectively	21,466.3	21,347.0
Regulatory assets	2,929.7	2,803.2
Equity investment in transmission affiliates	1,598.9	1,553.4
Goodwill	3,052.8	3,053.5
Other	757.1	619.9
Long-term assets	29,804.8	29,377.0
Total assets	31,785.6	31,590.5
Current liabilities
Short-term debt	1,200.3	1,444.6
Current portion of long-term debt	957.9	842.1
Accounts payable	592.8	859.9
Accrued payroll and benefits	107.4	169.1
Other	747.5	553.6
Current liabilities	3,605.9	3,869.3
Long-term liabilities
Long-term debt	8,617.5	8,746.6
Deferred income taxes	3,069.9	2,999.8
Deferred revenue, net	538.1	543.3
Regulatory liabilities	3,924.3	3,718.6
Environmental remediation liabilities	617.2	617.4
Pension and OPEB obligations	523.1	397.4
Other	1,191.4	1,206.3
Long-term liabilities	18,481.5	18,229.4
Commitments and contingencies (Note 19)
Common shareholders' equity
Common stock – $0.01 par value; 325,000,000 shares authorized; 315,538,808 and 315,574,624 shares outstanding, respectively	3.2	3.2
Additional paid in capital	4,267.3	4,278.5
Retained earnings	5,392.7	5,176.8
Accumulated other comprehensive income	4.6	2.9
Common shareholders' equity	9,667.8	9,461.4
Preferred stock of subsidiary	30.4	30.4
Total liabilities and equity	$ 31,785.6	$ 31,590.5