Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

Details of income tax expenses and deferred income taxes from continuing operations are provided in the following tables. The components of income tax expenses were as follows:



	Year Ended December 31,
	2012			2011			2010
	(in millions)
Federal income tax expense (benefit)
Current	$	33.7		$	(5.3	)	$	(16.6	)
Deferred	36.5			153.0			172.9
State income tax expense (benefit)
Current	0.7			2.9			(4.7		)
Deferred	(4.4		)	3.8			15.4
Total income tax expense	$	66.5		$	154.4		$	167.0

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The difference between the statutory federal income tax rate and the Company's effective income tax rate is explained as follows:



	Year Ended December 31,
	2012		2011		2010
Federal income taxes statutory rate	35.0	%	35.0	%	35.0	%
Increase (decrease) in rate as a result of:
State income taxes, net of federal income tax benefit	(1.2	)%	1.0	%	1.5	%
Penalties	(0.6	)%	—	%	—	%
Return to provision adjustment	0.4	%	1.3	%	0.2	%
Noncontrolling interest	(0.7	)%	(0.3	)%	(0.2	)%
Non-deductible Spin-off costs	—	%	—	%	0.5	%
Other	0.6	%	(0.7	)%	(0.1	)%
Effective income tax rate	33.5	%	36.3	%	36.9	%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]



	December 31,
	2012		2011
	(in millions)
Deferred tax liabilities
Property, plant and equipment	$	1,606.6	$	1,714.6
Commodity price and interest rate derivatives	69.4		147.2
Total deferred tax liabilities	1,676.0		1,861.8
Deferred tax assets
NOL and tax credit carryforwards	65.6		232.9
Employee benefits and compensation costs	47.7		42.9
Accrued litigation loss contingency	42.8		—
Bonus and vacation accrual	11.8		10.7
Other	9.6		5.2
Total deferred tax assets	177.5		291.7
Net deferred income tax liability	$	1,498.5	$	1,570.1
Balance sheet classification
Deferred income tax liability - current	$	5.0	$	85.4
Deferred income tax liability - non-current	1,493.5		1,484.7
Net deferred income tax liability	$	1,498.5	$	1,570.1

Summary of Operating Loss Carryforwards [Table Text Block]

The amounts and expiration dates of operating loss and tax credit carryforwards at December 31, 2012:



	Expiration Dates	Amounts
		(in millions)
State net operating loss and credit carryforwards	2014-2032	$	21.2
U.S. alternative minimum tax credit	Indefinite	44.4
Total		$	65.6