Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 8,919	$ 10,664
Restricted cash	117	119
Oil and gas revenue receivable	111,915	84,095
Joint interest billing and other receivables	32,502	17,725
Derivative assets	104,190	1,415
Other current assets	19,495	14,613
Total current assets	277,138	128,631
Oil And Gas Properties, Net, Using Full Cost Method Of Accounting [Abstract]
Proven	3,636,643	2,008,538
Unproven properties not being amortized	242,294	413,073
Property, plant and equipment	12,186	216,909
Deferred income taxes	30,640	6
Deferred financing costs and other	26,789	18,162
Total assets	4,225,690	2,785,319
Current liabilities:
Accounts payable	77,580	54,806
AccruedLiabilitiesCurrent	89,865	79,811
Production taxes payable	55,585	40,538
Senior Notes due March 2015	100,000	0
Interest Payable Current	46,098	31,865
Current deferred tax liabilities	30,638	0
Derivative liabilities	0	27,291
Capital cost accrual	45,952	173,165
Total current liabilities	445,718	407,476
Long-term debt	3,278,000	2,470,000
Deferred income tax liability	992	0
Deferred gain on sale of liquids gathering system	136,848	147,401
Other long-term obligations	152,472	91,932
CommitmentsAndContingencies
Shareholders' equity:
Common stock - no par value; authorized - unlimited; issued and outstanding - 152,896,315 and 152,990,123, respectively	495,913	487,273
Treasury stock	(6,213)	(1,961)
Retained earnings	(278,040)	(816,802)
Total shareholders' equity (deficit)	211,660	(331,490)
Total liabilities and shareholders' equity	$ 4,225,690	$ 2,785,319