Operations and Significant Accounting Policies (Details) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Inventories
Fuel	$ 23.5		$ 23.5		$ 22.9
Materials and Supplies	37.8		37.8		37.1
Total Inventories	61.3		61.3		60.0
Prepayments and Other Current Assets
Deferred Fuel Adjustment Clause	15.0		15.0		20.6
Other	5.6		5.6		8.0
Total Prepayments and Other Current Assets	20.6		20.6		28.6
Other Non-Current Liabilities
Asset Retirement Obligation	52.0		52.0		50.3
Other	48.9		48.9		43.1
Total Other Non-Current Liabilities	100.9		100.9		93.4
Cash Paid During the Period for
Interest - Net of Amounts Capitalized			21.9	16.3
Income Taxes			0.4	1.5
Noncash Investing and Financing Activities
Increase (Decrease) in Accounts Payable for Capital Additions to Property, Plant and Equipment	(13.2)	4.4	(13.2)	4.4
AFUDC - Equity	$ 0.5	$ 0.9	$ 1.1	$ 2.1

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Carrying amount as of the balance sheet date of capitalized fuel costs of a regulated entity that are expected to be recoverable through rate adjustments within one year or the normal operating cycle, if longer.

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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