Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities [Abstract]
Net Income (Loss)	$ 90,577	$ (2,581)
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depletion, depreciation and amoritzation	93,274	279,762
Deferred Income Tax Provision (Benefit)	1	(744)
Unrealized Gain (Loss) on Derivatives	0	84,675
Deferred gain on sale of liquids gathering system	(7,915)	(7,915)
Amounts charged against income before income tax benefit	3,967	5,509
Non-cash reorganization items, net	22,588	0
Other	6,618	6,295
Increase (Decrease) in Operating Capital [Abstract]
Restricted cash	(3,346)	2
Accounts receivable	(6,782)	49,604
Other current assets	(14,871)	(616)
Increase (Decrease) in Other Operating Assets	(818)	0
Accounts payable	(67,828)	(6,898)
Accrued liabilities	(3,102)	(4,469)
Production taxes payable	10,982	3,785
Interest payable	57,118	(4,577)
Other long-term obligations	(9,431)	7,040
Income taxes payable receivable	(234)	2,333
Net Cash Provided by (Used in) Operating Activities	170,798	411,205
Investing Activities [Abstract]
Acquisition Costs	0	3,964
Oil and gas property expenditures	(189,511)	(390,874)
Change in capital cost accrual	(10,730)	(20,585)
Inventory	136	3,177
Purchase of Capital Assets	3	(669)
Net Cash Provided by (Used in) Investing Activities	(200,102)	(404,987)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Borrowings on long-term debt	369,000	936,000
Payments on long-term debt	0	(906,000)
Deferred financing costs	0	6
Repurchased shares - net share settlements	(319)	(2,507)
Payment of contingent consideration	0	(17,049)
Net Cash Provided by (Used in) Financing Activities	368,681	10,450
Cash and Cash Equivalents, Period Increase (Decrease)	339,377	16,668
Cash and Cash Equivalents, at Carrying Value	4,143	8,919
Cash and Cash Equivalents, at Carrying Value	$ 343,520	$ 25,587