Income Tax Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Current Tax Expense (Benefit)
Federal - Current	$ 0	[1]	$ 0	[1]	$ 0	[1]	$ 7.2	[1]
State - Current	0.1	[1]	(1.9)	[1]	0.2	[1]	(1.0)	[1]
Total Current Tax Expense	0.1		(1.9)		0.2		6.2
Deferred Tax Expense
Federal - Deferred	4.0	[2]	8.2	[2]	10.8	[2]	18.0	[2]
State - Deferred	0	[2]	3.3	[2]	1.5	[2]	5.5	[2]
Deferred Tax Credits	(0.3)		(0.2)		(0.5)		(0.4)
Total Deferred Tax Expense	3.7		11.3		11.8		23.1
Total Income Tax Expense	3.8		9.4		12.0		29.3
Amount of income tax benefit (expense) related to Medicare Part D	2.9				2.9		(4.0)
Deferred tax adjustments					6.2
Effective tax rate					18.20%		41.00%
Effective tax rate, reduction due to income tax benefit					4.40%
Effective tax rate, reduction due to reversal of deferred tax liability					9.40%
Effective tax rate, statutory					41.00%		41.00%
Gross unrecognized tax benefits	11.3				11.3
Unrecognized tax benefits that would favorably impact effective tax rate	$ 0.6				$ 0.6

[1] For the quarter and six months ended June 30, 2011, the federal and state current tax expense was affected by a net operating loss (NOL) which resulted primarily from the bonus depreciation provision of tax legislation passed in 2010. The 2011 federal and state NOL will be carried forward to offset future taxable income. For the six months ended June 30, 2010, we recorded federal current tax expense, as the 2010 tax legislation allowing bonus depreciation was not enacted until the third quarter of 2010. The state current benefit for the quarter and six months ended June 30, 2010, was due to the completion of a state audit and state renewable tax credits.

[2] The quarter ended June 30, 2011, includes a $2.9 million income tax benefit related to the MPUC approval of our request to defer the retail portion of the tax charge taken in 2010 resulting from PPACA. The six months ended June 30, 2011, includes the second quarter item above and the reversal in the first quarter of 2011 of a $6.2 million deferred tax liability related to a revenue receivable that Minnesota Power agreed to forgo as part of a stipulation and settlement agreement in its 2010 rate case. Included in the six months ended June 30, 2010, is a charge of $4.0 million as a result of PPACA (See Note 5. Regulatory Matters).