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



	Year Ended December 31,
	2014			2013			2012
	(in millions)
Federal income tax provision (benefit)
Current	$	(324.0	)	$	(92.2	)	$	(10.3	)
Deferred	110.3			152.3			15.6
State income tax provision (benefit)
Current	(15.5		)	(1.4		)	(1.8		)
Deferred	(3.3		)	1.4			(5.4		)
Total income tax provision (benefit)	$	(232.5	)	$	60.1		$	(1.9	)

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,
	2014		2013		2012
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	(1.5	)%	(5.0	)%	(2,220.0	)%
State rate change	3.4	%	—	%	—	%
Penalties	—	%	0.4	%	80.0	%
Return to provision adjustment	(0.4	)%	5.0	%	1,400.0	%
Book impairment of goodwill	—	%	18.6	%	—	%
Other	(0.3	)%	(0.4	)%	325.0	%
Effective income tax rate	36.2	%	53.6	%	(380.0	)%

Significant components of the Company's deferred income taxes were as follows:



	December 31,
	2014		2013
	(in millions)
Deferred tax liabilities
Property, plant and equipment	$	1,402.9	$	1,455.6
Commodity price and interest rate derivatives	127.7		—
Total deferred tax liabilities	1,530.6		1,455.6
Deferred tax assets
Commodity price and interest rate derivatives	—		9.8
Net operating loss and tax credit carryforwards	11.7		54.4
Employee benefits and compensation costs	43.0		36.1
Accrued litigation loss contingency	—		0.8
Bonus and vacation accrual	16.3		9.0
Other	12.4		8.5
Total deferred tax assets	83.4		118.6
Net deferred income tax liability	$	1,447.2	$	1,337.0
Balance sheet classification
Deferred income tax asset - current	$	—	$	27.9
Deferred income tax liability - current	84.5		—
Deferred income tax liability - non-current	1,362.7		1,364.9
Net deferred income tax liability	$	1,447.2	$	1,337.0

The amounts and expiration dates of net operating loss and tax credit carryforwards at December 31, 2014 are as follows:



	Expiration Dates	Amounts
		(in millions)
State net operating loss and tax credit carryforwards	2015-2033	$	30.1
State net operating loss valuation allowance		(18.4		)
U.S. alternative minimum tax credit	Indefinite	—
Total		$	11.7

The valuation allowance of $18.4 million was established in 2014 against the available state net operating loss and is related primarily to losses incurred in Oklahoma. Due to the 2014 Midcontinent property sales in which the Company sold its interests in most of its properties in Oklahoma, the Company does not forecast sufficient taxable income to utilize the net operating loss in Oklahoma.