Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss)	$ 101,715	$ 16,433
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depletion, depreciation and amoritzation	63,181	61,468
Deferred gain on sale of liquids gathering system	(2,638)	(2,640)
Unrealized Gain (Loss) on Derivatives	36,319	44,715
Stock compensation	2,505	3,008
Other	1,043	539
Increase (Decrease) in Operating Capital [Abstract]
Restricted cash	2	2
Accounts receivable	(32,153)	8,357
Other current assets	(628)	298
Accounts payable	(3,047)	(8,247)
Accrued liabilities	11,141	(34,907)
Production taxes payable	3,325	68
Interest payable	(15,499)	(21,190)
Other long-term obligations	11,553	9,238
Income taxes payable receivable	(1,244)	(9,282)
Net Cash Provided by (Used in) Operating Activities	175,575	67,860
Net Cash Provided by (Used in) Investing Activities [Abstract]
Oil and gas property expenditures	(123,595)	(107,395)
Gathering system expenditures	(2,319)	(1,006)
Change in capital cost accrual	(4,195)	(49,420)
Proceeds from Sale of Productive Assets	0	(27)
Inventory	(911)	529
Purchase of Capital Assets	(676)	(10)
Net Cash Provided by (Used in) Investing Activities	(131,696)	(157,329)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings on long-term debt	195,000	314,000
Payments on long-term debt	(240,000)	(218,000)
Deferred financing costs	(164)	0
Repurchased shares - net share settlements	(1,738)	(5,085)
Proceeds from exercise of options	339	0
Net Cash Provided by (Used in) Financing Activities	(46,563)	90,915
Cash and Cash Equivalents, Period Increase (Decrease)	(2,684)	1,446
Cash and Cash Equivalents, at Carrying Value	10,664	12,921
Cash and Cash Equivalents, at Carrying Value	7,980	14,367
SUPPLEMENTAL INFORMATION:
Non-cash investing activities - oil and gas properties	$ 0	$ 12,650