Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Summary of Provision for Income Taxes from Continuing Operations

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

	Year Ended December 31,
	2014			2013			2012
Current income taxes (benefit)
Federal	$	2,045		$	—		$	—
State	1,504			—			(26		)
	3,549			—			(26		)
Deferred income tax benefit
Federal	(130,693		)	(77,046		)	(60,676		)
State	(4,534		)	(650		)	(8,000		)
	(135,227		)	(77,696		)	(68,676		)
	$	(131,678	)	$	(77,696	)	$	(68,702	)

Income Taxes Reconciliation

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,
	2014					2013					2012
Computed at federal statutory rate	$	(189,445	)	(35.0	)%	$	(77,268	)	(35.0	)%	$	(60,652	)	(35.0	)%
State income taxes, net of federal income tax benefit	(3,556		)	(0.6	)%	(650		)	(0.3	)%	(8,026		)	(4.6	)%
Change in valuation allowance	61,104			11.3	%	—			—	%	—			—	%
Other, net	219			—	%	222			0.1	%	(24		)	—	%
	$	(131,678	)	(24.3	)%	$	(77,696	)	(35.2	)%	$	(68,702	)	(39.6	)%

Summary of Principal Components of Net Deferred Income Tax Liability

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

	As of December 31,
	2014			2013
Deferred tax liabilities:
Property and equipment	$	6,347		$	248,164
Fair value of derivative instruments	57,707			—
Total deferred tax liabilities	64,054			248,164
Deferred tax assets:
Fair value of derivative instruments	—			1,665
Pension and postretirement benefits	2,370			2,248
Share-based compensation	7,171			6,907
Net operating loss (“NOL”) carryforwards	102,098			115,355
Deferred gains	33,704			—
Other	19,875			18,029
	165,218			144,204
Less:  Valuation allowance	(105,615		)	(35,727		)
Total deferred tax assets	59,603			108,477
	$	4,451		$	139,687