INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Schedule of principal components of deferred income tax assets and liabilities recognized in the balance sheets

The principal components of deferred income tax assets and liabilities recognized on the balance sheets as of December 31 are included in the table below. Certain temporary differences are netted in the table when the offsetting amount is recorded as a regulatory asset or liability. This is consistent with regulatory treatment.

(Millions)	2014		2013
Total deferred income tax assets	$	4.4	$	3.5
Deferred income tax liabilities
Plant-related	591.0		491.7
Employee benefits	83.9		81.0
Regulatory deferrals	42.4		44.4
Other	13.0		16.7
Total deferred income tax liabilities	$	730.3	$	633.8
Total net deferred income tax liabilities	$	725.9	$	630.3
Balance sheet presentation
Current deferred income tax liabilities – included in other current liabilities	$	3.8	$	10.8
Long-term deferred income tax liabilities	722.1		619.5
Total net deferred income tax liabilities	$	725.9	$	630.3

Schedule of components of the provision for income tax expense

The components of the provision for income taxes were as follows:

(Millions)	2014			2013			2012
Current provision
Federal	$	(12.8	)	$	(1.3	)	$	24.8
State	6.7			3.4			4.2
Total current provision	(6.1		)	2.1			29.0
Deferred provision
Federal	84.3			71.5			27.8
State	6.6			8.3			5.9
Total deferred provision	90.9			79.8			33.7
Interest	0.2			0.3			0.1
Investment tax credits
Deferral	—			—			0.2
Amortization	(0.3		)	(0.3		)	(0.4		)
Total provision for income taxes	$	84.7		$	81.9		$	62.6

Reconciliation of federal income taxes to the provision for income taxes reported in the income statement

The following table presents a reconciliation of the difference between the effective tax rate and the amount computed by applying the statutory federal tax rate to income before taxes.

	2014					2013					2012
(Millions, except for percentages)	Rate		Amount			Rate		Amount			Rate		Amount
Statutory federal income tax	35.0	%	$	78.9		35.0	%	$	76.9		35.0	%	$	69.1
State income taxes, net	4.8		10.9			4.8		10.5			4.4		8.7
Benefits and compensation	(1.0	)	(2.2		)	(0.9	)	(1.9		)	(3.6	)	(7.2		)
Federal tax credits	—		—			—		—			(3.5	)	(7.0		)
Other differences, net	(1.2	)	(2.9		)	(1.6	)	(3.6		)	(0.6	)	(1.0		)
Effective income tax	37.6	%	$	84.7		37.3	%	$	81.9		31.7	%	$	62.6

Reconciliation of the beginning and ending amount of unrecognized tax benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:

(Millions)	2014		2013			2012
Balance at January 1	$	—	$	0.3		$	0.5
Increase related to tax positions taken in prior years	—		0.7			—
Decrease related to tax positions taken in prior years	—		(0.4		)	—
Decrease related to settlements	—		(0.6		)	—
Decrease related to lapse of statutes	—		—			(0.2		)
Balance at December 31	$	—	$	—		$	0.3