Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities
Net income (loss)	$ (9,077)	$ 225,620	$ 22,405
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depletion, depreciation, and amortization	205,498	181,669	114,136
Exploration expense	5,250	2,952	14,415
Accretion of ARO liability	1,087	770	608
Amortization of debt issuance costs	6,043	6,878	2,677
Stock compensation expense	7,562	4,040	10,838
Other non-cash compensation expense	455	758	2,719
Amortization of deferred revenue	(1,960)	(1,154)	(469)
(Gain) loss on commodity derivatives	(158,753)	(189,641)	2,566
(Gain) loss on sales of assets	3	(297)	78
Deferred income tax provision	(2,892)	26,165	(156)
Other - net	(961)	376	79
Changes in assets and liabilities
Accounts receivable	64,510	(2,453)	(56,804)
Other assets	(251)	(565)	163
Accrued interest expense	7,050	7,823	1,891
Accounts payable and accrued liabilities	(54,534)	2,482	33,427
Net cash provided by operations	69,030	265,423	148,573
Cash flows from investing activities
Additions to oil and gas properties	(311,305)	(474,619)	(197,618)
Acquisition of properties			(178,173)
Net adjustments to purchase price of properties acquired		15,709
Proceeds from sales of assets	41	448	1,607
Acquisition of other property, plant and equipment	(1,101)	(1,683)	(1,634)
Current period settlements of matured derivative contracts	144,145	(3,654)	7,586
Change in restricted cash	(181)	(104)	(45)
Net cash used in investing	(168,401)	(463,903)	(368,277)
Cash flows from financing activities
Proceeds from issuance of long-term debt	85,000	170,000	220,000
Repayment under long-term debt	(335,000)	(468,000)	(172,000)
Proceeds from senior notes	236,475	500,000
Payment of debt issuance costs	(1,556)	(13,416)	(683)
Proceeds from sale of common stock	122,779		172,481
Purchase of treasury stock		(358)
Net cash provided by financing	107,698	188,226	219,798
Net increase (decrease) in cash	8,327	(10,254)	94
Cash
Beginning of period	13,566	23,820	23,726
End of period	21,893	13,566	23,820
Supplemental disclosure of cash flow information
Cash paid for interest	52,796	29,560	25,414
Cash paid for income taxes	(155)	155
Change in accrued additions to oil and gas properties	(111,210)	49,025	41,945
Current additions to ARO	$ 6,349	$ 1,995	$ 1,516