Regulatory Matters (Tables)

6 Months Ended

Jun. 30, 2011

Regulatory Matters [Abstract]

Schedule of Regulatory Assets and Liabilities

	June 30,	December 31,
Regulatory Assets and Liabilities	2011	2010
Millions
Current Regulatory Assets (a)
Deferred Fuel	$15.0	$20.6
Total Current Regulatory Assets	15.0	20.6
Non-Current Regulatory Assets
Future Benefit Obligations Under
Defined Benefit Pension and Other Postretirement Benefit Plans	249.5	257.9
Boswell Unit 3 Environmental Rider	-	20.5
Income Taxes	22.1	17.3
Asset Retirement Obligation	8.7	7.8
Medicare Part D	5.0	-
Premium on Reacquired Debt	1.7	1.8
Rate Case Expenses	1.0	1.4
Other	2.2	3.5
Total Non-Current Regulatory Assets	290.2	310.2
Total Regulatory Assets	$305.2	$330.8
Non-Current Regulatory Liabilities
Income Taxes	$22.2	$23.4
Plant Removal Obligations	16.4	16.9
Other	4.8	3.3
Total Non-Current Regulatory Liabilities	$43.4	$43.6

(a) Current regulatory assets are included in prepayments and other on the consolidated balance sheet.