CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Assets
Cash and cash equivalents	$ 42.3	$ 28.1
Collateral on deposit	64.2	50.9
Accounts receivable and accrued unbilled revenues, net of reserves of $43.4 and $47.1, respectively	669.7	737.7
Inventories	125.1	252.3
Assets from risk management activities	266.2	227.2
Regulatory assets	132.8	125.1
Deferred income taxes	101.6	94.2
Prepaid taxes	144.3	209.6
Other current assets	87.5	78.2
Current assets	1,633.7	1,803.3
Property, plant, and equipment, net of accumulated depreciation of $3,057.7 and $3,018.7, respectively	5,259.0	5,199.1
Regulatory assets	1,655.4	1,658.5
Assets from risk management activities	56.6	64.4
Equity method investments	490.6	476.3
Goodwill	658.3	658.4
Other long-term assets	125.4	123.2
Total assets	9,879.0	9,983.2
Liabilities and Equity
Short-term debt	305.5	303.3
Current portion of long-term debt	272.0	250.0
Accounts payable	331.2	426.6
Liabilities from risk management activities	400.0	311.6
Accrued taxes	75.4	70.5
Regulatory liabilities	96.5	67.5
Temporary LIFO liquidation credit	36.7
Other current liabilities	198.1	217.2
Current liabilities	1,715.4	1,646.7
Long-term debt	1,850.1	1,872.0
Deferred income taxes	1,108.7	1,070.7
Deferred investment tax credits	43.7	44.0
Regulatory liabilities	334.2	332.5
Environmental remediation liabilities	609.5	615.1
Pension and other postretirement benefit obligations	514.0	749.3
Liabilities from risk management activities	109.9	102.0
Asset retirement obligations	402.3	397.2
Other long-term liabilities	144.0	141.1
Long-term liabilities	5,116.4	5,323.9
Commitments and contingencies
Common stock - $1 par value; 200,000,000 shares authorized; 78,287,906 shares issued; 77,916,543 shares outstanding	78.3	78.3
Additional paid-in capital	2,566.5	2,579.1
Retained earnings	409.2	363.6
Accumulated other comprehensive loss	(41.0)	(42.5)
Shares in deferred compensation trust	(17.0)	(17.1)
Total common shareholders' equity	2,996.0	2,961.4
Preferred stock of subsidiary - $100 par value; 1,000,000 shares authorized; 511,882 shares issued; 510,495 shares outstanding	51.1	51.1
Noncontrolling interest in subsidiaries	0.1	0.1
Total liabilities and equity	$ 9,879.0	$ 9,983.2