Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss)	$ 207,763	$ 132,811
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depletion, depreciation and amoritzation	128,522	121,591
Deferred gain on sale of liquids gathering system	(5,276)	(5,276)
Unrealized Gain (Loss) on Derivatives	14,130	2,860
Stock compensation	1,029	6,062
Other	2,123	1,074
Increase (Decrease) in Operating Capital [Abstract]
Restricted cash	2	2
Accounts receivable	(22,975)	3,201
Other current assets	(396)	994
Accounts payable	4,674	(27,866)
Accrued liabilities	7,806	(12,752)
Production taxes payable	6,247	(8,479)
Interest payable	(438)	240
Other long-term obligations	5,228	3,431
Income taxes payable receivable	(1,788)	(8,759)
Net Cash Provided by (Used in) Operating Activities	346,651	209,134
Net Cash Provided by (Used in) Investing Activities [Abstract]
Acquisition Costs	(290)	0
Oil and gas property expenditures	(271,520)	(197,731)
Gathering system expenditures	(4,658)	(3,275)
Change in capital cost accrual	(38,836)	(51,383)
Proceeds from Sale of Productive Assets	0	(129)
Inventory	322	(520)
Purchase of Capital Assets	(2,188)	(195)
Net Cash Provided by (Used in) Investing Activities	(317,170)	(253,233)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings on long-term debt	458,000	498,000
Payments on long-term debt	(491,000)	(455,000)
Deferred financing costs	(164)	0
Repurchased shares - net share settlements	(2,557)	(5,265)
Proceeds from exercise of options	668	0
Net Cash Provided by (Used in) Financing Activities	(35,053)	37,735
Cash and Cash Equivalents, Period Increase (Decrease)	(5,572)	(6,364)
Cash and Cash Equivalents, at Carrying Value	10,664	12,921
Cash and Cash Equivalents, at Carrying Value	5,092	6,557
SUPPLEMENTAL INFORMATION:
Non-cash investing activities - oil and gas properties	$ 0	$ 12,651