Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

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,
	2013			2012			2011
Current income taxes (benefit)
Federal	$	—		$	—		$	1,279
State	—			(26		)	(3,933		)
	—			(26		)	(2,654		)
Deferred income tax benefit
Federal	(77,046		)	(60,676		)	(80,529		)
State	(650		)	(8,000		)	(4,972		)
	(77,696		)	(68,676		)	(85,501		)
	$	(77,696	)	$	(68,702	)	$	(88,155	)

Income Taxes Reconciliation

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

	Year Ended December 31,
	2013					2012					2011
Computed at federal statutory rate	$	(77,268	)	(35.0	)%	$	(60,652	)	(35.0	)%	$	(77,374	)	(35.0	)%
State income taxes, net of federal income tax benefit	(650		)	(0.3	)%	(8,026		)	(4.6	)%	(4,825		)	(2.2	)%
Other, net	222			0.1	%	(24		)	—	%	(5,956		)	(2.7	)%
	$	(77,696	)	(35.2	)%	$	(68,702	)	(39.6	)%	$	(88,155	)	(39.9	)%

Summary of Principal Components of Net Deferred Income Tax Liability

The following table summarizes the principal components of our net deferred income tax liability as of the dates presented: 

	As of December 31,
	2013			2012
Deferred tax liabilities:
Property and equipment	$	248,164		$	311,002
Fair value of derivative instruments	—			5,268
Total deferred tax liabilities	248,164			316,270
Deferred tax assets:
Fair value of derivative instruments	1,665			—
Pension and postretirement benefits	2,248			2,864
Share-based compensation	6,907			10,760
Net operating loss (“NOL”) carryforwards	115,355			102,407
Other	18,029			15,788
	144,204			131,819
Less:  Valuation allowance	(35,727		)	(26,686		)
Total deferred tax assets	108,477			105,133
Net deferred tax liability	$	139,687		$	211,137