Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 84.5	$ 38.9
Accounts receivable and unbilled revenues, net of reserves of $149.2 and $143.2, respectively	1,280.9	1,350.7
Materials, supplies, and inventories	548.2	539.0
Prepayments	256.8	210.0
Other	77.2	74.9
Current assets	2,247.6	2,213.5
Long-term assets
Property, plant, and equipment, net of accumulated depreciation of $8,515.9 and $8,618.5, respectively	22,000.9	21,347.0
Regulatory assets	3,805.1	2,803.2
Equity investment in transmission affiliates	1,665.3	1,553.4
Goodwill	3,052.8	3,053.5
Other	704.1	619.9
Long-term assets	31,228.2	29,377.0
Total assets	33,475.8	31,590.5
Current liabilities
Short-term debt	1,440.1	1,444.6
Current portion of long-term debt	365.0	842.1
Accounts payable	876.4	859.9
Accrued payroll and benefits	185.4	169.1
Other	464.8	553.6
Current liabilities	3,331.7	3,869.3
Long-term liabilities
Long-term debt	9,994.0	8,746.6
Deferred income taxes	3,388.1	2,999.8
Deferred revenue, net	520.4	543.3
Regulatory liabilities	4,251.6	3,718.6
Environmental remediation liabilities	616.4	617.4
Pension and OPEB obligations	422.8	397.4
Other	1,108.1	1,206.3
Long-term liabilities	20,301.4	18,229.4
Commitments and Contingencies (Note 22)
Common shareholders' equity
Common stock - $0.01 par value; 325,000,000 shares authorized; 315,523,192 and 315,574,624 shares outstanding, respectively	3.2	3.2
Additional paid in capital	4,250.1	4,278.5
Retained earnings	5,538.2	5,176.8
Accumulated other comprehensive (loss) income	(2.6)	2.9
Common shareholders' equity	9,788.9	9,461.4
Preferred stock of subsidiary	30.4	30.4
Noncontrolling interests	23.4	0.0
Total liabilities and equity	$ 33,475.8	$ 31,590.5