Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Schedule of componenets of provision for income taxes

The provision for income taxes consists of the following:

	For the Years Ended December 31,
	2013			2012			2011
	(in thousands)
Current portion of income tax expense (benefit)
Federal	$	—		$	—		$	(1,757	)
State	2,121			370			1,553
Deferred portion of income tax expense (benefit)	105,555			(29,638		)	123,789
Total income tax expense (benefit)	$	107,676		$	(29,268	)	$	123,585
Effective tax rate	38.6		%	35.0		%	36.5		%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

The components of the net deferred income tax liabilities are as follows:

	As of December 31,
	2013			2012
	(in thousands)
Deferred tax liabilities:
Oil and gas properties	$	768,463		$	678,624
Derivative asset	9,529			15,942
Other	1,245			6,443
Total deferred tax liabilities	779,237			701,009
Deferred tax assets:
Federal and state tax net operating loss carryovers	91,788			113,522
Net Profits Plan liability	20,913			29,233
Stock compensation	18,820			18,026
Other long-term liabilities	13,341			16,739
Total deferred tax assets	144,862			177,520
Valuation allowance	(5,001		)	(5,315		)
Net deferred tax assets	139,861			172,205
Total net deferred tax liabilities	639,376			528,804
Less: current deferred income tax liabilities	(172		)	(5,442		)
Add: current deferred income tax assets	10,921			14,021
Non-current net deferred tax liabilities	$	650,125		$	537,383
Current federal income tax refundable	$	4,630		$	2,511
Current state income tax refundable	$	—		$	853
Current state income tax payable	$	1,460		$	—

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	For the Years Ended December 31,
	2013			2012			2011
	(in thousands)
Federal statutory tax expense (benefit)	$	97,514		$	(29,231	)	$	118,652
Increase (decrease) in tax resulting from:
State tax expense (benefit) (net of federal benefit)	9,400			(992		)	6,458
Research and development credit	—			(970		)	(4,516		)
Change in valuation allowance	(314		)	1,524			1,627
Statutory depletion	(154		)	(210		)	(341		)
Other	1,230			611			1,705
Income tax expense (benefit)	$	107,676		$	(29,268	)	$	123,585

Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block]

The total amount recorded for unrecognized tax benefits is presented below:

	For the Years Ended December 31,
	2013		2012		2011
	(in thousands)
Beginning balance	$	2,278	$	1,961	$	807
Additions based on tax positions related to current year	—		—		1,172
Additions for tax positions of prior years	80		317		183
Reductions for lapse of statute of limitations	—		—		(201		)
Ending balance	$	2,358	$	2,278	$	1,961