Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Summary of income tax expense

The following table is a summary of income tax expense for each of the years ended December 31:

Income Taxes	2014			2013			2012
	(Millions of Dollars)
Current tax expense	$	33.6		$	25.2		$	13.1
Deferred income taxes, net	329.2			313.8			294.4
Investment tax credit, net	(1.1		)	(1.1		)	(1.2		)
Total Income Tax Expense	$	361.7		$	337.9		$	306.3

The provision for income taxes for each of the years ended December 31 differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to income before income taxes as a result of the following:

The provision for income taxes for each of the years ended December 31 differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to income before income taxes as a result of the following:

	2014					2013					2012
				Effective					Effective					Effective
Income Tax Expense	Amount			Tax Rate		Amount			Tax Rate		Amount			Tax Rate
	(Millions of Dollars)
Expected tax at statutory federal tax rates	$	332.5		35.0	%	$	320.3		35.0	%	$	298.4		35.0	%
State income taxes net of federal tax benefit	50.5			5.3	%	49.0			5.3	%	43.3			5.1	%
Production tax credits	(17.4		)	(1.8	)%	(16.7		)	(1.8	)%	(15.9		)	(1.9	)%
Treasury Grant	(3.8		)	(0.4	)%	(7.4		)	(0.8	)%	—			—	%
AFUDC - Equity	(1.9		)	(0.2	)%	(6.4		)	(0.7	)%	(12.3		)	(1.4	)%
Investment tax credit restored	(1.1		)	(0.1	)%	(1.1		)	(0.1	)%	(1.2		)	(0.1	)%
Domestic production activities deduction	—			—	%	—			—	%	(12.6		)	(1.5	)%
Other, net	2.9			0.3	%	0.2			—	%	6.6			0.7	%
Total Income Tax Expense	$	361.7		38.1	%	$	337.9		36.9	%	$	306.3		35.9	%

Components of deferred income taxes classified as net current assets and net long-term liabilities

The components of deferred income taxes classified as net current assets and net long-term liabilities as of December 31 are as follows:

Deferred Tax Assets	2014		2013
	(Millions of Dollars)
Current
Future federal tax benefits	$	221.7	$	309.7
Employee benefits and compensation	13.7		13.8
Other	47.7		56.0
Total Current Deferred Tax Assets	283.1		379.5
Non-current
Deferred revenues	221.3		237.0
Employee benefits and compensation	98.2		95.6
Future federal tax benefits	—		32.5
Property-related	28.8		28.2
Construction advances	18.9		18.3
Other	51.8		62.9
Total Non-Current Deferred Tax Assets	419.0		474.5
Total Deferred Tax Assets	$	702.1	$	854.0

Deferred Tax Liabilities	2014		2013
	(Millions of Dollars)
Current
Prepaid items	$	40.4	$	69.5
Total Current Deferred Tax Liabilities	40.4		69.5
Non-current
Property-related	2,750.4		2,574.4
Employee benefits and compensation	242.5		238.5
Investment in transmission affiliate	188.6		169.9
Deferred transmission costs	58.5		50.8
Other	85.7		74.9
Total Non-current Deferred Tax Liabilities	3,325.7		3,108.5
Total Deferred Tax Liabilities	$	3,366.1	$	3,178.0
Consolidated Balance Sheet Presentation	2014		2013
Current Deferred Tax Asset	$	242.7	$	310.0
Non-Current Deferred Tax Liability	$	2,906.7	$	2,634.0

Reconciliation of the beginning and ending amount of unrecognized tax benefits

We previously adopted accounting guidance related to uncertainty in income taxes. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:

	2014			2013
	(Millions of Dollars)
Balance as of January 1	$	8.4		$	11.3
Reductions for tax positions of prior years	(1.2		)	(2.9		)
Balance as of December 31	$	7.2		$	8.4