Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss)	$ 518	$ 207,763
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depletion, depreciation and amoritzation	186,956	128,522
Deferred gain on sale of liquids gathering system	(5,276)	(5,276)
Deferred Income Tax Provision (Benefit)	(527)	0
Unrealized Gain (Loss) on Derivatives	48,765	14,130
Stock compensation	2,829	1,029
Other	4,973	2,123
Increase (Decrease) in Operating Capital [Abstract]
Restricted cash	2	2
Accounts receivable	42,763	(22,975)
Other current assets	(28)	(396)
Accounts payable	(16,293)	4,674
Accrued liabilities	(19,911)	7,806
Production taxes payable	3,239	6,247
Interest payable	(3,439)	(438)
Other long-term obligations	(4,496)	5,228
Income taxes payable receivable	3,249	(1,788)
Net Cash Provided by (Used in) Operating Activities	243,324	346,651
Net Cash Provided by (Used in) Investing Activities [Abstract]
Acquisition Costs	3,964	(290)
Oil and gas property expenditures	(267,522)	(271,520)
Gathering system expenditures	0	(4,658)
Change in capital cost accrual	(15,616)	(38,836)
Proceeds from Sale of Productive Assets	0	0
Inventory	345	322
Purchase of Capital Assets	(504)	(2,188)
Net Cash Provided by (Used in) Investing Activities	(279,333)	(317,170)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings on long-term debt	714,000	458,000
Payments on long-term debt	(662,000)	(491,000)
Deferred financing costs	6	(164)
Repurchased shares - net share settlements	(2,486)	(2,557)
Payment of contingent consideration	(17,049)	0
Proceeds from exercise of options	0	668
Net Cash Provided by (Used in) Financing Activities	32,471	(35,053)
Cash and Cash Equivalents, Period Increase (Decrease)	(3,538)	(5,572)
Cash and Cash Equivalents, at Carrying Value	8,919	10,664
Cash and Cash Equivalents, at Carrying Value	$ 5,381	$ 5,092