CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Assets
Cash and cash equivalents	$ 16.0	$ 6.5
Accounts receivable and accrued unbilled revenues, net of reserves of $4.5 and $2.5, respectively	206.8	258.3
Receivables from related parties	4.1	5.0
Inventories
Fuel and gas	44.5	76.3
Materials and supplies, at average cost	37.6	33.3
Regulatory assets	22.4	26.1
Prepaid taxes	85.7	84.7
Other current assets	12.4	13.3
Current assets	429.5	503.5
Property, plant, and equipment, net of accumulated depreciation of $1,434.8 and $1,336.0, respectively	2,756.6	2,353.0
Regulatory assets	579.4	536.2
Goodwill	36.4	36.4
Other long-term assets	124.7	92.8
Total assets	3,926.6	3,521.9
Liabilities and Shareholders' Equity
Short-term debt	303.7	95.4
Current portion of long-term debt	125.0	147.0
Accounts payable	106.7	131.0
Payables to related parties	14.3	13.5
Regulatory liabilities	37.5	27.6
Other current liabilities	60.4	61.8
Current liabilities	647.6	476.3
Long-term debt to parent	7.0	7.2
Long-term debt	724.4	724.4
Deferred income taxes	577.1	539.0
Deferred investment tax credits	8.4	8.5
Regulatory liabilities	281.9	281.0
Environmental remediation liabilities	66.3	68.8
Pension and other postretirement benefit obligations	142.7	164.6
Payables to related parties	6.6	6.7
Other long-term liabilities	73.6	72.7
Long-term liabilities	1,888.0	1,872.9
Commitments and contingencies
Preferred stock - $100 par value; 1,000,000 shares authorized; 511,882 shares issued and outstanding	51.2	51.2
Common stock - $4 par value; 32,000,000 shares authorized; 23,896,962 shares issued and outstanding	95.6	95.6
Additional paid-in capital	756.3	555.4
Retained earnings	487.9	470.5
Total liabilities and shareholders' equity	$ 3,926.6	$ 3,521.9