Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 4,143	$ 8,919	$ 10,664	$ 12,921
Restricted cash	115	117
Oil and gas revenue receivable	61,881	111,915
Joint interest billing and other receivables	11,356	32,502
Derivative assets	0	104,190
Income tax receivable	5,150	6,246
Inventory	4,269	10,216
Deferred financing costs	20,477	0
Other current assets	3,270	3,033
Total current assets	110,661	277,138
Oil And Gas Properties, Net, Using Full Cost Method Of Accounting [Abstract]
Proven	851,145	3,636,643
Unproven properties not being amortized	0	242,294
Property, plant and equipment	8,844	12,186
Deferred income taxes	1	30,640
Deferred financing costs and other	835	26,789
Total assets	971,486	4,225,690
Current liabilities:
Accounts payable	93,415	77,580
Accrued liabilities	72,428	89,865
Production taxes payable	52,273	55,585
Current maturities of long term debt	3,390,000	100,000
Interest Payable Current	42,657	46,098
Current deferred tax liabilities	0	30,638
Derivative liabilities	0	0
Capital cost accrual	20,571	45,952
Total current liabilities	3,671,344	445,718
Long-term debt	0	3,278,000
Deferred income tax liability	0	992
Deferred gain on sale of liquids gathering system	126,295	136,848
Other long-term obligations	$ 165,784	$ 152,472
Commitments and contingencies
Shareholders' equity:
Common stock - no par value; authorized - unlimited; issued and outstanding - 153,255,989 and 152,896,315, respectively	$ 502,050	$ 495,913
Treasury stock	(176)	(6,213)
Retained earnings	(3,493,811)	(278,040)
Total shareholders' equity (deficit)	(2,991,937)	211,660	$ (331,490)	$ (577,867)
Total liabilities and shareholders' equity	$ 971,486	$ 4,225,690