Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities
Net income (loss)	$ 45,094	$ (33,261)	$ (10,309)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Unrealized loss (gain) on derivatives	7,232	4,802	(5,138)
Depletion, depreciation and amortization	98,395	80,454	31,754
Accretion of asset retirement obligations	348	256	209
Full-cost ceiling impairment	21,229	63,475	35,673
Stock-based compensation expense	3,897	140	2,406
Deferred income tax provision (benefit)	9,293	(1,430)	(5,475)
Loss on asset sales and inventory impairment	192	485	154
Changes in operating assets and liabilities
Accounts receivable	(2,160)	(16,342)	(1,523)
Lease and well equipment inventory	243	50	21
Prepaid expenses	(668)	50	650
Other assets	(548)	(673)	(814)
Accounts payable, accrued liabilities and other current liabilities	(3,638)	19,740	13,497
Royalties payable	1,257	4,685	873
Advances from joint interest owners	(1,515)	1,515	(723)
Income taxes payable	404	0	0
Other long-term liabilities	415	282	613
Net cash provided by operating activities	179,470	124,228	61,868
Investing activities
Oil and natural gas properties capital expenditures	(363,192)	(300,689)	(156,431)
Expenditures for other property and equipment	(3,977)	(7,332)	(4,671)
Purchases of certificates of deposit	(61)	(496)	(4,298)
Maturities of certificates of deposit	291	1,601	5,312
Net cash used in investing activities	(366,939)	(306,916)	(160,088)
Financing activities
Repayments of borrowings under Credit Agreement	(130,000)	(123,000)	(103,000)
Borrowings under Credit Agreement	180,000	160,000	191,000
Proceeds from issuance of common stock	149,069	146,510	592
Swing sale profit contribution	0	24	0
Cost to issue equity	(7,390)	(11,599)	(1,710)
Proceeds from stock options exercised	0	2,660	837
Taxes paid related to net share settlement of stock-based compensation	(18)	0	0
Payment of dividends - Class B	0	(96)	(275)
Net cash provided by financing activities	191,661	174,499	87,444
Increase (decrease) in cash	4,192	(8,189)	(10,776)
Cash at beginning of year	2,095	10,284	21,060
Cash at end of year	$ 6,287	$ 2,095	$ 10,284