Supplemental Financial Information (Parent - Balance Sheet) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 4,143,000	$ 8,919,000	$ 10,664,000	$ 12,921,000
Restricted cash	115,000	117,000
Oil and gas revenue receivable	61,881,000	111,915,000
Joint interest billing and other receivables	11,356,000	32,502,000
Derivative assets	0	104,190,000
Income tax receivable	5,150,000	6,246,000
Inventory	4,269,000	10,216,000
Deferred financing costs	20,477,000	0
Other current assets	3,270,000	3,033,000
Total current assets	110,661,000	277,138,000
Oil And Gas Properties, Net, Using Full Cost Method Of Accounting [Abstract]
Proven	851,145,000	3,636,643,000
Unproven properties not being amortized	0	242,294,000
Property, plant and equipment	8,844,000	12,186,000
Deferred income taxes	1,000	30,640,000
Other non-current assets	835,000	26,789,000
Total assets	971,486,000	4,225,690,000
Current liabilities:
Accounts payable	93,415,000	77,580,000
Accrued and other current liabilities	72,428,000	89,865,000
Production taxes payable	52,273,000	55,585,000
Current maturities of long term debt	3,390,000,000	100,000,000
Interest Payable Current	42,657,000	46,098,000
Current deferred tax liabilities	0	30,638,000
Derivative liabilities	0	0
Capital cost accrual	20,571,000	45,952,000
Total current liabilities	3,671,344,000	445,718,000
Long-term debt	0	3,278,000,000
Deferred income tax liability	0	992,000
Deferred gain on sale of liquids gathering system	126,295,000	136,848,000
Other long-term obligations	$ 165,784,000	$ 152,472,000
Commitments and contingencies
Shareholders' equity:
Common stock - no par value; authorized - unlimited; issued and outstanding - 153,255,989 and 152,896,315, respectively	$ 502,050,000	$ 495,913,000
Treasury stock	(176,000)	(6,213,000)
Retained earnings	(3,493,811,000)	(278,040,000)
Total shareholders' equity (deficit)	(2,991,937,000)	211,660,000	(331,490,000)	(577,867,000)
Total liabilities and shareholders' equity	971,486,000	4,225,690,000
Parent [Member]
Current assets:
Cash and cash equivalents	523,000	772,000	$ 629,000	$ 3,455,000
Accounts receivable from related companies	64,542,000	33,146,000
Other current assets	21,918,000	6,246,000
Total current assets	86,983,000	40,164,000
Oil And Gas Properties, Net, Using Full Cost Method Of Accounting [Abstract]
Other non-current assets	24,197,000	27,339,000
Investment in unconsolidated affiliates	0	1,461,226,000
Total assets	111,180,000	1,528,729,000
Current liabilities:
Accrued and other current liabilities	0	31,000
Current maturities of long term debt	1,300,000,000	0
Interest Payable Current	14,166,000	16,046,000
Total current liabilities	1,314,166,000	16,077,000
Long-term debt	0	1,300,000,000
Advances to unconsolidated affiliates	1,788,951,000	0
Other long-term obligations	0	992,000
Shareholders' equity:
Total shareholders' equity (deficit)	(2,991,937,000)	211,660,000
Total liabilities and shareholders' equity	$ 111,180,000	$ 1,528,729,000