Income Taxes

The following table summarizes our provision for income taxes for the periods presented:



	Year Ended December 31,
	2015			2014			2013
Current income taxes (benefit)
Federal	$	(660	)	$	2,045		$	—
State	1			1,504			—
	(659		)	3,549			—
Deferred income tax benefit
Federal	(261		)	(130,693		)	(77,046		)
State	(4,451		)	(4,534		)	(650		)
	(4,712		)	(135,227		)	(77,696		)
	$	(5,371	)	$	(131,678	)	$	(77,696	)

The following table reconciles the difference between the income tax benefit computed by applying the statutory tax rate to our loss before income taxes and our reported income tax benefit for the periods presented:



	Year Ended December 31,
	2015					2014					2013
Computed at federal statutory rate	$	(555,916	)	35.0	%	$	(189,445	)	35.0	%	$	(77,268	)	35.0	%
State income taxes, net of federal income tax benefit	(4,438		)	0.3	%	(3,556		)	0.6	%	(650		)	0.3	%
Change in valuation allowance	554,879			(35.0	)%	61,104			(11.3	)%	—			—	%
Other, net	104			—	%	219			—	%	222			(0.1	)%
	$	(5,371	)	0.3	%	$	(131,678	)	24.3	%	$	(77,696	)	35.2	%

The following table summarizes the principal components of our deferred income tax assets and liabilities as of the dates presented:



	As of December 31,
	2015			2014
Deferred tax assets:
Property and equipment	$	417,535		$	—
Pension and postretirement benefits	2,276			2,370
Share-based compensation	7,393			7,171
Net operating loss (“NOL”) carryforwards	222,971			102,098
Deferred gains	30,382			33,704
Other	16,637			19,875
	697,194			165,218
Less: Valuation allowance	(662,909		)	(105,615		)
Total net deferred tax assets	34,285			59,603
Deferred tax liabilities:
Fair value of derivative instruments	34,285			57,707
Property and equipment	—			6,347
Total net deferred tax liabilities	34,285			64,054
Net deferred tax liabilities	$	—		$	4,451

In 2015 and in connection with the retrospective application of ASU 2015–17, we reclassified $0.1 million of deferred income taxes previously classified as a component of current assets at December 31, 2014 as a reduction to our noncurrent deferred income tax liabilities.

As of December 31, 2015, we had federal NOL carryforwards of approximately $508.1 million, which, if not utilized, expire between 2032 and 2035, and state NOL carryforwards of approximately $69.4 million, which expire between 2024 and 2035. Because of the change in ownership provisions of the Tax Reform Act of 1986, use of a portion of our federal NOL may be limited in future periods.

As of December 31, 2014, we carried a valuation allowance against our federal and state deferred tax assets of $105.6 million. We incurred a pre-tax loss in 2015 which, when aggregated with the prior two years, resulted in a pre-tax loss for the three year period ended December 31, 2015. We considered both the positive and negative evidence in determining whether it was more likely than not that some portion or all of our deferred tax assets will be realized. On the basis of this evaluation, we increased the federal and state deferred tax asset valuation allowance by $557.3 million which resulted in an ending balance of $662.9 million as of December 31, 2015. The amount of deferred tax asset considered realizable could, however, be adjusted if estimates of future taxable income during the carryforward period are reduced or increased or if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as our projections for growth.

We had no liability for unrecognized tax benefits as of December 31, 2015 and 2014. There were no interest and penalty charges recognized during the years ended December 31, 2015, 2014 and 2013. Tax years from 2012 forward remain open for examination by the Internal Revenue Service and various state jurisdictions.